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    Subject[PATCH v9] tilegx network driver: initial support
    This change adds support for the tilegx network driver based on the
    GXIO IORPC support in the tilegx software stack, using the on-chip
    mPIPE packet processing engine.

    Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
    ---
    This change fixes some bugs that were discovered during additional
    testing of the TSO refactoring. In addition, I added a comment
    explaining why we provide TSO support as essentially driver-side GSO.

    The previous v8 version of the patch (from 10 days ago) received no
    feedback; if anyone would care to provide feedback on this version of
    the driver, it would be much appreciated. Thanks!

    drivers/net/ethernet/tile/Kconfig | 2 +
    drivers/net/ethernet/tile/Makefile | 4 +-
    drivers/net/ethernet/tile/tilegx.c | 1875 ++++++++++++++++++++++++++++++++++++
    3 files changed, 1879 insertions(+), 2 deletions(-)
    create mode 100644 drivers/net/ethernet/tile/tilegx.c

    diff --git a/drivers/net/ethernet/tile/Kconfig b/drivers/net/ethernet/tile/Kconfig
    index 2d9218f..098b1c4 100644
    --- a/drivers/net/ethernet/tile/Kconfig
    +++ b/drivers/net/ethernet/tile/Kconfig
    @@ -7,6 +7,8 @@ config TILE_NET
    depends on TILE
    default y
    select CRC32
    + select TILE_GXIO_MPIPE if TILEGX
    + select HIGH_RES_TIMERS if TILEGX
    ---help---
    This is a standard Linux network device driver for the
    on-chip Tilera Gigabit Ethernet and XAUI interfaces.
    diff --git a/drivers/net/ethernet/tile/Makefile b/drivers/net/ethernet/tile/Makefile
    index f634f14..0ef9eef 100644
    --- a/drivers/net/ethernet/tile/Makefile
    +++ b/drivers/net/ethernet/tile/Makefile
    @@ -4,7 +4,7 @@

    obj-$(CONFIG_TILE_NET) += tile_net.o
    ifdef CONFIG_TILEGX
    -tile_net-objs := tilegx.o mpipe.o iorpc_mpipe.o dma_queue.o
    +tile_net-y := tilegx.o
    else
    -tile_net-objs := tilepro.o
    +tile_net-y := tilepro.o
    endif
    diff --git a/drivers/net/ethernet/tile/tilegx.c b/drivers/net/ethernet/tile/tilegx.c
    new file mode 100644
    index 0000000..a729499
    --- /dev/null
    +++ b/drivers/net/ethernet/tile/tilegx.c
    @@ -0,0 +1,1875 @@
    +/*
    + * Copyright 2012 Tilera Corporation. All Rights Reserved.
    + *
    + * This program is free software; you can redistribute it and/or
    + * modify it under the terms of the GNU General Public License
    + * as published by the Free Software Foundation, version 2.
    + *
    + * This program is distributed in the hope that it will be useful, but
    + * WITHOUT ANY WARRANTY; without even the implied warranty of
    + * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
    + * NON INFRINGEMENT. See the GNU General Public License for
    + * more details.
    + */
    +
    +#include <linux/module.h>
    +#include <linux/init.h>
    +#include <linux/moduleparam.h>
    +#include <linux/sched.h>
    +#include <linux/kernel.h> /* printk() */
    +#include <linux/slab.h> /* kmalloc() */
    +#include <linux/errno.h> /* error codes */
    +#include <linux/types.h> /* size_t */
    +#include <linux/interrupt.h>
    +#include <linux/in.h>
    +#include <linux/irq.h>
    +#include <linux/netdevice.h> /* struct device, and other headers */
    +#include <linux/etherdevice.h> /* eth_type_trans */
    +#include <linux/skbuff.h>
    +#include <linux/ioctl.h>
    +#include <linux/cdev.h>
    +#include <linux/hugetlb.h>
    +#include <linux/in6.h>
    +#include <linux/timer.h>
    +#include <linux/hrtimer.h>
    +#include <linux/ktime.h>
    +#include <linux/io.h>
    +#include <linux/ctype.h>
    +#include <linux/ip.h>
    +#include <linux/tcp.h>
    +
    +#include <asm/checksum.h>
    +#include <asm/homecache.h>
    +#include <gxio/mpipe.h>
    +#include <arch/sim.h>
    +
    +/* Default transmit lockup timeout period, in jiffies. */
    +#define TILE_NET_TIMEOUT (5 * HZ)
    +
    +/* The maximum number of distinct channels (idesc.channel is 5 bits). */
    +#define TILE_NET_CHANNELS 32
    +
    +/* Maximum number of idescs to handle per "poll". */
    +#define TILE_NET_BATCH 128
    +
    +/* Maximum number of packets to handle per "poll". */
    +#define TILE_NET_WEIGHT 64
    +
    +/* Number of entries in each iqueue. */
    +#define IQUEUE_ENTRIES 512
    +
    +/* Number of entries in each equeue. */
    +#define EQUEUE_ENTRIES 2048
    +
    +/* Total header bytes per equeue slot. Must be big enough for 2 bytes
    + * of NET_IP_ALIGN alignment, plus 14 bytes (?) of L2 header, plus up to
    + * 60 bytes of actual TCP header. We round up to align to cache lines.
    + */
    +#define HEADER_BYTES 128
    +
    +/* Maximum completions per cpu per device (must be a power of two).
    + * ISSUE: What is the right number here? If this is too small, then
    + * egress might block waiting for free space in a completions array.
    + * ISSUE: At the least, allocate these only for initialized echannels.
    + */
    +#define TILE_NET_MAX_COMPS 64
    +
    +#define MAX_FRAGS (MAX_SKB_FRAGS + 1)
    +
    +/* Size of completions data to allocate.
    + * ISSUE: Probably more than needed since we don't use all the channels.
    + */
    +#define COMPS_SIZE (TILE_NET_CHANNELS * sizeof(struct tile_net_comps))
    +
    +/* Size of NotifRing data to allocate. */
    +#define NOTIF_RING_SIZE (IQUEUE_ENTRIES * sizeof(gxio_mpipe_idesc_t))
    +
    +/* Timeout to wake the per-device TX timer after we stop the queue.
    + * We don't want the timeout too short (adds overhead, and might end
    + * up causing stop/wake/stop/wake cycles) or too long (affects performance).
    + * For the 10 Gb NIC, 30 usec means roughly 30+ 1500-byte packets.
    + */
    +#define TX_TIMER_DELAY_USEC 30
    +
    +/* Timeout to wake the per-cpu egress timer to free completions. */
    +#define EGRESS_TIMER_DELAY_USEC 1000
    +
    +MODULE_AUTHOR("Tilera Corporation");
    +MODULE_LICENSE("GPL");
    +
    +/* A "packet fragment" (a chunk of memory). */
    +struct frag {
    + void *buf;
    + size_t length;
    +};
    +
    +/* A single completion. */
    +struct tile_net_comp {
    + /* The "complete_count" when the completion will be complete. */
    + s64 when;
    + /* The buffer to be freed when the completion is complete. */
    + struct sk_buff *skb;
    +};
    +
    +/* The completions for a given cpu and device. */
    +struct tile_net_comps {
    + /* The completions. */
    + struct tile_net_comp comp_queue[TILE_NET_MAX_COMPS];
    + /* The number of completions used. */
    + unsigned long comp_next;
    + /* The number of completions freed. */
    + unsigned long comp_last;
    +};
    +
    +/* Info for a specific cpu. */
    +struct tile_net_info {
    + /* The NAPI struct. */
    + struct napi_struct napi;
    + /* Packet queue. */
    + gxio_mpipe_iqueue_t iqueue;
    + /* Our cpu. */
    + int my_cpu;
    + /* True if iqueue is valid. */
    + bool has_iqueue;
    + /* NAPI flags. */
    + bool napi_added;
    + bool napi_enabled;
    + /* Number of small sk_buffs which must still be provided. */
    + unsigned int num_needed_small_buffers;
    + /* Number of large sk_buffs which must still be provided. */
    + unsigned int num_needed_large_buffers;
    + /* A timer for handling egress completions. */
    + struct hrtimer egress_timer;
    + /* True if "egress_timer" is scheduled. */
    + bool egress_timer_scheduled;
    + /* Comps for each egress channel. */
    + struct tile_net_comps *comps_for_echannel[TILE_NET_CHANNELS];
    +};
    +
    +/* Info for egress on a particular egress channel. */
    +struct tile_net_egress {
    + /* The "equeue". */
    + gxio_mpipe_equeue_t *equeue;
    + /* The headers for TSO. */
    + unsigned char *headers;
    +};
    +
    +/* Info for a specific device. */
    +struct tile_net_priv {
    + /* Our network device. */
    + struct net_device *dev;
    + /* The primary link. */
    + gxio_mpipe_link_t link;
    + /* The primary channel, if open, else -1. */
    + int channel;
    + /* The "loopify" egress link, if needed. */
    + gxio_mpipe_link_t loopify_link;
    + /* The "loopify" egress channel, if open, else -1. */
    + int loopify_channel;
    + /* The egress channel (channel or loopify_channel). */
    + int echannel;
    + /* Total stats. */
    + struct net_device_stats stats;
    + /* Timer to wake up tx queue */
    + struct hrtimer tx_wake_timer;
    +};
    +
    +/* Egress info, indexed by "priv->echannel" (lazily created as needed). */
    +static struct tile_net_egress egress_for_echannel[TILE_NET_CHANNELS];
    +
    +/* Devices currently associated with each channel.
    + * NOTE: The array entry can become NULL after ifconfig down, but
    + * we do not free the underlying net_device structures, so it is
    + * safe to use a pointer after reading it from this array.
    + */
    +static struct net_device *tile_net_devs_for_channel[TILE_NET_CHANNELS];
    +
    +/* A mutex for "tile_net_devs_for_channel". */
    +static DEFINE_MUTEX(tile_net_devs_for_channel_mutex);
    +
    +/* The per-cpu info. */
    +static DEFINE_PER_CPU(struct tile_net_info, per_cpu_info);
    +
    +/* The "context" for all devices. */
    +static gxio_mpipe_context_t context;
    +
    +/* The small/large "buffer stacks". */
    +static int small_buffer_stack = -1;
    +static int large_buffer_stack = -1;
    +
    +/* Amount of memory allocated for each buffer stack. */
    +static size_t buffer_stack_size;
    +
    +/* The actual memory allocated for the buffer stacks. */
    +static void *small_buffer_stack_va;
    +static void *large_buffer_stack_va;
    +
    +/* The buckets. */
    +static int first_bucket = -1;
    +static int num_buckets = 1;
    +
    +/* The ingress irq. */
    +static int ingress_irq = -1;
    +
    +/* Text value of tile_net.cpus if passed as a module parameter. */
    +static char *network_cpus_string;
    +
    +/* The actual cpus in "network_cpus". */
    +static struct cpumask network_cpus_map;
    +
    +/* If "loopify=LINK" was specified, this is "LINK". */
    +static char *loopify_link_name;
    +
    +/* If "tile_net.custom" was specified, this is non-NULL. */
    +static char *custom_str;
    +
    +/* The "tile_net.cpus" argument specifies the cpus that are dedicated
    + * to handle ingress packets.
    + *
    + * The parameter should be in the form "tile_net.cpus=m-n[,x-y]", where
    + * m, n, x, y are integer numbers that represent the cpus that can be
    + * neither a dedicated cpu nor a dataplane cpu.
    + */
    +static bool network_cpus_init(void)
    +{
    + char buf[1024];
    + int rc;
    +
    + if (network_cpus_string == NULL)
    + return false;
    +
    + rc = cpulist_parse_crop(network_cpus_string, &network_cpus_map);
    + if (rc != 0) {
    + pr_warn("tile_net.cpus=%s: malformed cpu list\n",
    + network_cpus_string);
    + return false;
    + }
    +
    + /* Remove dedicated cpus. */
    + cpumask_and(&network_cpus_map, &network_cpus_map, cpu_possible_mask);
    +
    + if (cpumask_empty(&network_cpus_map)) {
    + pr_warn("Ignoring empty tile_net.cpus='%s'.\n",
    + network_cpus_string);
    + return false;
    + }
    +
    + cpulist_scnprintf(buf, sizeof(buf), &network_cpus_map);
    + pr_info("Linux network CPUs: %s\n", buf);
    + return true;
    +}
    +
    +module_param_named(cpus, network_cpus_string, charp, 0444);
    +MODULE_PARM_DESC(cpus, "cpulist of cores that handle network interrupts");
    +
    +/* The "tile_net.loopify=LINK" argument causes the named device to
    + * actually use "loop0" for ingress, and "loop1" for egress. This
    + * allows an app to sit between the actual link and linux, passing
    + * (some) packets along to linux, and forwarding (some) packets sent
    + * out by linux.
    + */
    +module_param_named(loopify, loopify_link_name, charp, 0444);
    +MODULE_PARM_DESC(loopify, "name the device to use loop0/1 for ingress/egress");
    +
    +/* The "tile_net.custom" argument causes us to ignore the "conventional"
    + * classifier metadata, in particular, the "l2_offset".
    + */
    +module_param_named(custom, custom_str, charp, 0444);
    +MODULE_PARM_DESC(custom, "indicates a (heavily) customized classifier");
    +
    +/* Atomically update a statistics field.
    + * Note that on TILE-Gx, this operation is fire-and-forget on the
    + * issuing core (single-cycle dispatch) and takes only a few cycles
    + * longer than a regular store when the request reaches the home cache.
    + * No expensive bus management overhead is required.
    + */
    +static void tile_net_stats_add(unsigned long value, unsigned long *field)
    +{
    + BUILD_BUG_ON(sizeof(atomic_long_t) != sizeof(unsigned long));
    + atomic_long_add(value, (atomic_long_t *)field);
    +}
    +
    +/* Allocate and push a buffer. */
    +static bool tile_net_provide_buffer(bool small)
    +{
    + int stack = small ? small_buffer_stack : large_buffer_stack;
    + const unsigned long buffer_alignment = 128;
    + struct sk_buff *skb;
    + int len;
    +
    + len = sizeof(struct sk_buff **) + buffer_alignment;
    + len += (small ? 128 : 1664);
    + skb = dev_alloc_skb(len);
    + if (skb == NULL)
    + return false;
    +
    + /* Make room for a back-pointer to 'skb' and guarantee alignment. */
    + skb_reserve(skb, sizeof(struct sk_buff **));
    + skb_reserve(skb, -(long)skb->data & (buffer_alignment - 1));
    +
    + /* Save a back-pointer to 'skb'. */
    + *(struct sk_buff **)(skb->data - sizeof(struct sk_buff **)) = skb;
    +
    + /* Make sure "skb" and the back-pointer have been flushed. */
    + wmb();
    +
    + gxio_mpipe_push_buffer(&context, stack,
    + (void *)va_to_tile_io_addr(skb->data));
    +
    + return true;
    +}
    +
    +/* Convert a raw mpipe buffer to its matching skb pointer. */
    +static struct sk_buff *mpipe_buf_to_skb(void *va)
    +{
    + /* Acquire the associated "skb". */
    + struct sk_buff **skb_ptr = va - sizeof(*skb_ptr);
    + struct sk_buff *skb = *skb_ptr;
    +
    + /* Paranoia. */
    + if (skb->data != va) {
    + /* Panic here since there's a reasonable chance
    + * that corrupt buffers means generic memory
    + * corruption, with unpredictable system effects.
    + */
    + panic("Corrupt linux buffer! va=%p, skb=%p, skb->data=%p",
    + va, skb, skb->data);
    + }
    +
    + return skb;
    +}
    +
    +static void tile_net_pop_all_buffers(int stack)
    +{
    + for (;;) {
    + tile_io_addr_t addr =
    + (tile_io_addr_t)gxio_mpipe_pop_buffer(&context, stack);
    + if (addr == 0)
    + break;
    + dev_kfree_skb_irq(mpipe_buf_to_skb(tile_io_addr_to_va(addr)));
    + }
    +}
    +
    +/* Provide linux buffers to mPIPE. */
    +static void tile_net_provide_needed_buffers(struct tile_net_info *info)
    +{
    + while (info->num_needed_small_buffers != 0) {
    + if (!tile_net_provide_buffer(true))
    + goto oops;
    + info->num_needed_small_buffers--;
    + }
    +
    + while (info->num_needed_large_buffers != 0) {
    + if (!tile_net_provide_buffer(false))
    + goto oops;
    + info->num_needed_large_buffers--;
    + }
    +
    + return;
    +
    +oops:
    + /* Add a description to the page allocation failure dump. */
    + pr_notice("Tile %d still needs some buffers\n", info->my_cpu);
    +}
    +
    +static inline bool filter_packet(struct net_device *dev, void *buf)
    +{
    + /* Filter packets received before we're up. */
    + if (dev == NULL || !(dev->flags & IFF_UP))
    + return true;
    +
    + /* Filter out packets that aren't for us. */
    + if (!(dev->flags & IFF_PROMISC) &&
    + !is_multicast_ether_addr(buf) &&
    + compare_ether_addr(dev->dev_addr, buf) != 0)
    + return true;
    +
    + return false;
    +}
    +
    +static void tile_net_receive_skb(struct net_device *dev, struct sk_buff *skb,
    + struct tile_net_info *info,
    + gxio_mpipe_idesc_t *idesc, unsigned long len)
    +{
    + struct tile_net_priv *priv = netdev_priv(dev);
    +
    + /* Encode the actual packet length. */
    + skb_put(skb, len);
    +
    + skb->protocol = eth_type_trans(skb, dev);
    +
    + /* Acknowledge "good" hardware checksums. */
    + if (idesc->cs && idesc->csum_seed_val == 0xFFFF)
    + skb->ip_summed = CHECKSUM_UNNECESSARY;
    +
    + netif_receive_skb(skb);
    +
    + /* Update stats. */
    + tile_net_stats_add(1, &priv->stats.rx_packets);
    + tile_net_stats_add(len, &priv->stats.rx_bytes);
    +
    + /* Need a new buffer. */
    + if (idesc->size == GXIO_MPIPE_BUFFER_SIZE_128)
    + info->num_needed_small_buffers++;
    + else
    + info->num_needed_large_buffers++;
    +}
    +
    +/* Handle a packet. Return true if "processed", false if "filtered". */
    +static bool tile_net_handle_packet(struct tile_net_info *info,
    + gxio_mpipe_idesc_t *idesc)
    +{
    + struct net_device *dev = tile_net_devs_for_channel[idesc->channel];
    + uint8_t l2_offset;
    + void *va;
    + void *buf;
    + unsigned long len;
    + bool filter;
    +
    + /* Drop packets for which no buffer was available.
    + * NOTE: This happens under heavy load.
    + */
    + if (idesc->be) {
    + struct tile_net_priv *priv = netdev_priv(dev);
    + tile_net_stats_add(1, &priv->stats.rx_dropped);
    + gxio_mpipe_iqueue_consume(&info->iqueue, idesc);
    + if (net_ratelimit())
    + pr_info("Dropping packet (insufficient buffers).\n");
    + return false;
    + }
    +
    + /* Get the "l2_offset", if allowed. */
    + l2_offset = custom_str ? 0 : gxio_mpipe_idesc_get_l2_offset(idesc);
    +
    + /* Get the raw buffer VA (includes "headroom"). */
    + va = tile_io_addr_to_va((unsigned long)(long)idesc->va);
    +
    + /* Get the actual packet start/length. */
    + buf = va + l2_offset;
    + len = idesc->l2_size - l2_offset;
    +
    + /* Point "va" at the raw buffer. */
    + va -= NET_IP_ALIGN;
    +
    + filter = filter_packet(dev, buf);
    + if (filter) {
    + gxio_mpipe_iqueue_drop(&info->iqueue, idesc);
    + } else {
    + struct sk_buff *skb = mpipe_buf_to_skb(va);
    +
    + /* Skip headroom, and any custom header. */
    + skb_reserve(skb, NET_IP_ALIGN + l2_offset);
    +
    + tile_net_receive_skb(dev, skb, info, idesc, len);
    + }
    +
    + gxio_mpipe_iqueue_consume(&info->iqueue, idesc);
    + return !filter;
    +}
    +
    +/* Handle some packets for the current CPU.
    + *
    + * This function handles up to TILE_NET_BATCH idescs per call.
    + *
    + * ISSUE: Since we do not provide new buffers until this function is
    + * complete, we must initially provide enough buffers for each network
    + * cpu to fill its iqueue and also its batched idescs.
    + *
    + * ISSUE: The "rotting packet" race condition occurs if a packet
    + * arrives after the queue appears to be empty, and before the
    + * hypervisor interrupt is re-enabled.
    + */
    +static int tile_net_poll(struct napi_struct *napi, int budget)
    +{
    + struct tile_net_info *info = &__get_cpu_var(per_cpu_info);
    + unsigned int work = 0;
    + gxio_mpipe_idesc_t *idesc;
    + int i, n;
    +
    + /* Process packets. */
    + while ((n = gxio_mpipe_iqueue_try_peek(&info->iqueue, &idesc)) > 0) {
    + for (i = 0; i < n; i++) {
    + if (i == TILE_NET_BATCH)
    + goto done;
    + if (tile_net_handle_packet(info, idesc + i)) {
    + if (++work >= budget)
    + goto done;
    + }
    + }
    + }
    +
    + /* There are no packets left. */
    + napi_complete(&info->napi);
    +
    + /* Re-enable hypervisor interrupts. */
    + gxio_mpipe_enable_notif_ring_interrupt(&context, info->iqueue.ring);
    +
    + /* HACK: Avoid the "rotting packet" problem. */
    + if (gxio_mpipe_iqueue_try_peek(&info->iqueue, &idesc) > 0)
    + napi_schedule(&info->napi);
    +
    + /* ISSUE: Handle completions? */
    +
    +done:
    + tile_net_provide_needed_buffers(info);
    +
    + return work;
    +}
    +
    +/* Handle an ingress interrupt on the current cpu. */
    +static irqreturn_t tile_net_handle_ingress_irq(int irq, void *unused)
    +{
    + struct tile_net_info *info = &__get_cpu_var(per_cpu_info);
    + napi_schedule(&info->napi);
    + return IRQ_HANDLED;
    +}
    +
    +/* Free some completions. This must be called with interrupts blocked. */
    +static int tile_net_free_comps(gxio_mpipe_equeue_t *equeue,
    + struct tile_net_comps *comps,
    + int limit, bool force_update)
    +{
    + int n = 0;
    + while (comps->comp_last < comps->comp_next) {
    + unsigned int cid = comps->comp_last % TILE_NET_MAX_COMPS;
    + struct tile_net_comp *comp = &comps->comp_queue[cid];
    + if (!gxio_mpipe_equeue_is_complete(equeue, comp->when,
    + force_update || n == 0))
    + break;
    + dev_kfree_skb_irq(comp->skb);
    + comps->comp_last++;
    + if (++n == limit)
    + break;
    + }
    + return n;
    +}
    +
    +/* Add a completion. This must be called with interrupts blocked.
    + * tile_net_equeue_try_reserve() will have ensured a free completion entry.
    + */
    +static void add_comp(gxio_mpipe_equeue_t *equeue,
    + struct tile_net_comps *comps,
    + uint64_t when, struct sk_buff *skb)
    +{
    + int cid = comps->comp_next % TILE_NET_MAX_COMPS;
    + comps->comp_queue[cid].when = when;
    + comps->comp_queue[cid].skb = skb;
    + comps->comp_next++;
    +}
    +
    +static void tile_net_schedule_tx_wake_timer(struct net_device *dev)
    +{
    + struct tile_net_priv *priv = netdev_priv(dev);
    +
    + hrtimer_start(&priv->tx_wake_timer,
    + ktime_set(0, TX_TIMER_DELAY_USEC * 1000UL),
    + HRTIMER_MODE_REL);
    +}
    +
    +static enum hrtimer_restart tile_net_handle_tx_wake_timer(struct hrtimer *t)
    +{
    + struct net_device *dev;
    + struct tile_net_priv *priv;
    +
    + priv = container_of(t, struct tile_net_priv, tx_wake_timer);
    + dev = priv->dev;
    +
    + if (netif_queue_stopped(dev))
    + netif_wake_queue(dev);
    +
    + return HRTIMER_NORESTART;
    +}
    +
    +/* Make sure the egress timer is scheduled.
    + *
    + * Note that we use "schedule if not scheduled" logic instead of the more
    + * obvious "reschedule" logic, because "reschedule" is fairly expensive.
    + */
    +static void tile_net_schedule_egress_timer(struct tile_net_info *info)
    +{
    + if (!info->egress_timer_scheduled) {
    + hrtimer_start(&info->egress_timer,
    + ktime_set(0, EGRESS_TIMER_DELAY_USEC * 1000UL),
    + HRTIMER_MODE_REL_PINNED);
    + info->egress_timer_scheduled = true;
    + }
    +}
    +
    +/* The "function" for "info->egress_timer".
    + *
    + * This timer will reschedule itself as long as there are any pending
    + * completions expected for this tile.
    + */
    +static enum hrtimer_restart tile_net_handle_egress_timer(struct hrtimer *t)
    +{
    + struct tile_net_info *info = &__get_cpu_var(per_cpu_info);
    + unsigned long irqflags;
    + bool pending = false;
    + int i;
    +
    + local_irq_save(irqflags);
    +
    + /* The timer is no longer scheduled. */
    + info->egress_timer_scheduled = false;
    +
    + /* Free all possible comps for this tile. */
    + for (i = 0; i < TILE_NET_CHANNELS; i++) {
    + struct tile_net_egress *egress = &egress_for_echannel[i];
    + struct tile_net_comps *comps = info->comps_for_echannel[i];
    + if (comps->comp_last >= comps->comp_next)
    + continue;
    + tile_net_free_comps(egress->equeue, comps, -1, true);
    + pending = pending || (comps->comp_last < comps->comp_next);
    + }
    +
    + /* Reschedule timer if needed. */
    + if (pending)
    + tile_net_schedule_egress_timer(info);
    +
    + local_irq_restore(irqflags);
    +
    + return HRTIMER_NORESTART;
    +}
    +
    +/* Helper function for "tile_net_update()".
    + * "dev" (i.e. arg) is the device being brought up or down,
    + * or NULL if all devices are now down.
    + */
    +static void tile_net_update_cpu(void *arg)
    +{
    + struct net_device *dev = arg;
    + struct tile_net_info *info = &__get_cpu_var(per_cpu_info);
    +
    + if (!info->has_iqueue)
    + return;
    +
    + if (dev != NULL) {
    + if (!info->napi_added) {
    + netif_napi_add(dev, &info->napi,
    + tile_net_poll, TILE_NET_WEIGHT);
    + info->napi_added = true;
    + }
    + if (!info->napi_enabled) {
    + napi_enable(&info->napi);
    + info->napi_enabled = true;
    + }
    + enable_percpu_irq(ingress_irq, 0);
    + } else {
    + disable_percpu_irq(ingress_irq);
    + if (info->napi_enabled) {
    + napi_disable(&info->napi);
    + info->napi_enabled = false;
    + }
    + /* FIXME: Drain the iqueue. */
    + }
    +}
    +
    +/* Helper function for tile_net_open() and tile_net_stop().
    + * Always called under tile_net_devs_for_channel_mutex.
    + */
    +static int tile_net_update(struct net_device *dev)
    +{
    + static gxio_mpipe_rules_t rules; /* too big to fit on the stack */
    + bool saw_channel = false;
    + int channel;
    + int rc;
    + int cpu;
    +
    + gxio_mpipe_rules_init(&rules, &context);
    +
    + for (channel = 0; channel < TILE_NET_CHANNELS; channel++) {
    + if (tile_net_devs_for_channel[channel] == NULL)
    + continue;
    + if (!saw_channel) {
    + saw_channel = true;
    + gxio_mpipe_rules_begin(&rules, first_bucket,
    + num_buckets, NULL);
    + gxio_mpipe_rules_set_headroom(&rules, NET_IP_ALIGN);
    + }
    + gxio_mpipe_rules_add_channel(&rules, channel);
    + }
    +
    + /* NOTE: This can fail if there is no classifier.
    + * ISSUE: Can anything else cause it to fail?
    + */
    + rc = gxio_mpipe_rules_commit(&rules);
    + if (rc != 0) {
    + netdev_warn(dev, "gxio_mpipe_rules_commit failed: %d\n", rc);
    + return -EIO;
    + }
    +
    + /* Update all cpus, sequentially (to protect "netif_napi_add()"). */
    + for_each_online_cpu(cpu)
    + smp_call_function_single(cpu, tile_net_update_cpu,
    + (saw_channel ? dev : NULL), 1);
    +
    + /* HACK: Allow packets to flow in the simulator. */
    + if (saw_channel)
    + sim_enable_mpipe_links(0, -1);
    +
    + return 0;
    +}
    +
    +/* Allocate and initialize mpipe buffer stacks, and register them in
    + * the mPIPE TLBs, for both small and large packet sizes.
    + * This routine supports tile_net_init_mpipe(), below.
    + */
    +static int init_buffer_stacks(struct net_device *dev, int num_buffers)
    +{
    + pte_t hash_pte = pte_set_home((pte_t) { 0 }, PAGE_HOME_HASH);
    + int rc;
    +
    + /* Compute stack bytes; we round up to 64KB and then use
    + * alloc_pages() so we get the required 64KB alignment as well.
    + */
    + buffer_stack_size =
    + ALIGN(gxio_mpipe_calc_buffer_stack_bytes(num_buffers),
    + 64 * 1024);
    +
    + /* Allocate two buffer stack indices. */
    + rc = gxio_mpipe_alloc_buffer_stacks(&context, 2, 0, 0);
    + if (rc < 0) {
    + netdev_err(dev, "gxio_mpipe_alloc_buffer_stacks failed: %d\n",
    + rc);
    + return rc;
    + }
    + small_buffer_stack = rc;
    + large_buffer_stack = rc + 1;
    +
    + /* Allocate the small memory stack. */
    + small_buffer_stack_va =
    + alloc_pages_exact(buffer_stack_size, GFP_KERNEL);
    + if (small_buffer_stack_va == NULL) {
    + netdev_err(dev,
    + "Could not alloc %zd bytes for buffer stacks\n",
    + buffer_stack_size);
    + return -ENOMEM;
    + }
    + rc = gxio_mpipe_init_buffer_stack(&context, small_buffer_stack,
    + GXIO_MPIPE_BUFFER_SIZE_128,
    + small_buffer_stack_va,
    + buffer_stack_size, 0);
    + if (rc != 0) {
    + netdev_err(dev, "gxio_mpipe_init_buffer_stack: %d\n", rc);
    + return rc;
    + }
    + rc = gxio_mpipe_register_client_memory(&context, small_buffer_stack,
    + hash_pte, 0);
    + if (rc != 0) {
    + netdev_err(dev,
    + "gxio_mpipe_register_buffer_memory failed: %d\n",
    + rc);
    + return rc;
    + }
    +
    + /* Allocate the large buffer stack. */
    + large_buffer_stack_va =
    + alloc_pages_exact(buffer_stack_size, GFP_KERNEL);
    + if (large_buffer_stack_va == NULL) {
    + netdev_err(dev,
    + "Could not alloc %zd bytes for buffer stacks\n",
    + buffer_stack_size);
    + return -ENOMEM;
    + }
    + rc = gxio_mpipe_init_buffer_stack(&context, large_buffer_stack,
    + GXIO_MPIPE_BUFFER_SIZE_1664,
    + large_buffer_stack_va,
    + buffer_stack_size, 0);
    + if (rc != 0) {
    + netdev_err(dev, "gxio_mpipe_init_buffer_stack failed: %d\n",
    + rc);
    + return rc;
    + }
    + rc = gxio_mpipe_register_client_memory(&context, large_buffer_stack,
    + hash_pte, 0);
    + if (rc != 0) {
    + netdev_err(dev,
    + "gxio_mpipe_register_buffer_memory failed: %d\n",
    + rc);
    + return rc;
    + }
    +
    + return 0;
    +}
    +
    +/* Allocate per-cpu resources (memory for completions and idescs).
    + * This routine supports tile_net_init_mpipe(), below.
    + */
    +static int alloc_percpu_mpipe_resources(struct net_device *dev,
    + int cpu, int ring)
    +{
    + struct tile_net_info *info = &per_cpu(per_cpu_info, cpu);
    + int order, i, rc;
    + struct page *page;
    + void *addr;
    +
    + /* Allocate the "comps". */
    + order = get_order(COMPS_SIZE);
    + page = homecache_alloc_pages(GFP_KERNEL, order, cpu);
    + if (page == NULL) {
    + netdev_err(dev, "Failed to alloc %zd bytes comps memory\n",
    + COMPS_SIZE);
    + return -ENOMEM;
    + }
    + addr = pfn_to_kaddr(page_to_pfn(page));
    + memset(addr, 0, COMPS_SIZE);
    + for (i = 0; i < TILE_NET_CHANNELS; i++)
    + info->comps_for_echannel[i] =
    + addr + i * sizeof(struct tile_net_comps);
    +
    + /* If this is a network cpu, create an iqueue. */
    + if (cpu_isset(cpu, network_cpus_map)) {
    + order = get_order(NOTIF_RING_SIZE);
    + page = homecache_alloc_pages(GFP_KERNEL, order, cpu);
    + if (page == NULL) {
    + netdev_err(dev,
    + "Failed to alloc %zd bytes iqueue memory\n",
    + NOTIF_RING_SIZE);
    + return -ENOMEM;
    + }
    + addr = pfn_to_kaddr(page_to_pfn(page));
    + rc = gxio_mpipe_iqueue_init(&info->iqueue, &context, ring++,
    + addr, NOTIF_RING_SIZE, 0);
    + if (rc < 0) {
    + netdev_err(dev,
    + "gxio_mpipe_iqueue_init failed: %d\n", rc);
    + return rc;
    + }
    + info->has_iqueue = true;
    + }
    +
    + return ring;
    +}
    +
    +/* Initialize NotifGroup and buckets.
    + * This routine supports tile_net_init_mpipe(), below.
    + */
    +static int init_notif_group_and_buckets(struct net_device *dev,
    + int ring, int network_cpus_count)
    +{
    + int group, rc;
    +
    + /* Allocate one NotifGroup. */
    + rc = gxio_mpipe_alloc_notif_groups(&context, 1, 0, 0);
    + if (rc < 0) {
    + netdev_err(dev, "gxio_mpipe_alloc_notif_groups failed: %d\n",
    + rc);
    + return rc;
    + }
    + group = rc;
    +
    + /* Initialize global num_buckets value. */
    + if (network_cpus_count > 4)
    + num_buckets = 256;
    + else if (network_cpus_count > 1)
    + num_buckets = 16;
    +
    + /* Allocate some buckets, and set global first_bucket value. */
    + rc = gxio_mpipe_alloc_buckets(&context, num_buckets, 0, 0);
    + if (rc < 0) {
    + netdev_err(dev, "gxio_mpipe_alloc_buckets failed: %d\n", rc);
    + return rc;
    + }
    + first_bucket = rc;
    +
    + /* Init group and buckets. */
    + rc = gxio_mpipe_init_notif_group_and_buckets(
    + &context, group, ring, network_cpus_count,
    + first_bucket, num_buckets,
    + GXIO_MPIPE_BUCKET_STICKY_FLOW_LOCALITY);
    + if (rc != 0) {
    + netdev_err(
    + dev,
    + "gxio_mpipe_init_notif_group_and_buckets failed: %d\n",
    + rc);
    + return rc;
    + }
    +
    + return 0;
    +}
    +
    +/* Create an irq and register it, then activate the irq and request
    + * interrupts on all cores. Note that "ingress_irq" being initialized
    + * is how we know not to call tile_net_init_mpipe() again.
    + * This routine supports tile_net_init_mpipe(), below.
    + */
    +static int tile_net_setup_interrupts(struct net_device *dev)
    +{
    + int cpu, rc;
    +
    + rc = create_irq();
    + if (rc < 0) {
    + netdev_err(dev, "create_irq failed: %d\n", rc);
    + return rc;
    + }
    + ingress_irq = rc;
    + tile_irq_activate(ingress_irq, TILE_IRQ_PERCPU);
    + rc = request_irq(ingress_irq, tile_net_handle_ingress_irq,
    + 0, NULL, NULL);
    + if (rc != 0) {
    + netdev_err(dev, "request_irq failed: %d\n", rc);
    + destroy_irq(ingress_irq);
    + ingress_irq = -1;
    + return rc;
    + }
    +
    + for_each_online_cpu(cpu) {
    + struct tile_net_info *info = &per_cpu(per_cpu_info, cpu);
    + if (info->has_iqueue) {
    + gxio_mpipe_request_notif_ring_interrupt(
    + &context, cpu_x(cpu), cpu_y(cpu),
    + 1, ingress_irq, info->iqueue.ring);
    + }
    + }
    +
    + return 0;
    +}
    +
    +/* Undo any state set up partially by a failed call to tile_net_init_mpipe. */
    +static void tile_net_init_mpipe_fail(void)
    +{
    + int cpu;
    +
    + /* Do cleanups that require the mpipe context first. */
    + if (small_buffer_stack >= 0)
    + tile_net_pop_all_buffers(small_buffer_stack);
    + if (large_buffer_stack >= 0)
    + tile_net_pop_all_buffers(large_buffer_stack);
    +
    + /* Destroy mpipe context so the hardware no longer owns any memory. */
    + gxio_mpipe_destroy(&context);
    +
    + for_each_online_cpu(cpu) {
    + struct tile_net_info *info = &per_cpu(per_cpu_info, cpu);
    + free_pages((unsigned long)(info->comps_for_echannel[0]),
    + get_order(COMPS_SIZE));
    + info->comps_for_echannel[0] = NULL;
    + free_pages((unsigned long)(info->iqueue.idescs),
    + get_order(NOTIF_RING_SIZE));
    + info->iqueue.idescs = NULL;
    + }
    +
    + if (small_buffer_stack_va)
    + free_pages_exact(small_buffer_stack_va, buffer_stack_size);
    + if (large_buffer_stack_va)
    + free_pages_exact(large_buffer_stack_va, buffer_stack_size);
    +
    + small_buffer_stack_va = NULL;
    + large_buffer_stack_va = NULL;
    + large_buffer_stack = -1;
    + small_buffer_stack = -1;
    + first_bucket = -1;
    +}
    +
    +/* The first time any tilegx network device is opened, we initialize
    + * the global mpipe state. If this step fails, we fail to open the
    + * device, but if it succeeds, we never need to do it again, and since
    + * tile_net can't be unloaded, we never undo it.
    + *
    + * Note that some resources in this path (buffer stack indices,
    + * bindings from init_buffer_stack, etc.) are hypervisor resources
    + * that are freed implicitly by gxio_mpipe_destroy().
    + */
    +static int tile_net_init_mpipe(struct net_device *dev)
    +{
    + int i, num_buffers, rc;
    + int cpu;
    + int first_ring, ring;
    + int network_cpus_count = cpus_weight(network_cpus_map);
    +
    + if (!hash_default) {
    + netdev_err(dev, "Networking requires hash_default!\n");
    + return -EIO;
    + }
    +
    + rc = gxio_mpipe_init(&context, 0);
    + if (rc != 0) {
    + netdev_err(dev, "gxio_mpipe_init failed: %d\n", rc);
    + return -EIO;
    + }
    +
    + /* Set up the buffer stacks. */
    + num_buffers =
    + network_cpus_count * (IQUEUE_ENTRIES + TILE_NET_BATCH);
    + rc = init_buffer_stacks(dev, num_buffers);
    + if (rc != 0)
    + goto fail;
    +
    + /* Provide initial buffers. */
    + rc = -ENOMEM;
    + for (i = 0; i < num_buffers; i++) {
    + if (!tile_net_provide_buffer(true)) {
    + netdev_err(dev, "Cannot allocate initial sk_bufs!\n");
    + goto fail;
    + }
    + }
    + for (i = 0; i < num_buffers; i++) {
    + if (!tile_net_provide_buffer(false)) {
    + netdev_err(dev, "Cannot allocate initial sk_bufs!\n");
    + goto fail;
    + }
    + }
    +
    + /* Allocate one NotifRing for each network cpu. */
    + rc = gxio_mpipe_alloc_notif_rings(&context, network_cpus_count, 0, 0);
    + if (rc < 0) {
    + netdev_err(dev, "gxio_mpipe_alloc_notif_rings failed %d\n",
    + rc);
    + goto fail;
    + }
    +
    + /* Init NotifRings per-cpu. */
    + first_ring = rc;
    + ring = first_ring;
    + for_each_online_cpu(cpu) {
    + rc = alloc_percpu_mpipe_resources(dev, cpu, ring);
    + if (rc < 0)
    + goto fail;
    + ring = rc;
    + }
    +
    + /* Initialize NotifGroup and buckets. */
    + rc = init_notif_group_and_buckets(dev, first_ring, network_cpus_count);
    + if (rc != 0)
    + goto fail;
    +
    + /* Create and enable interrupts. */
    + rc = tile_net_setup_interrupts(dev);
    + if (rc != 0)
    + goto fail;
    +
    + return 0;
    +
    +fail:
    + tile_net_init_mpipe_fail();
    + return rc;
    +}
    +
    +/* Create persistent egress info for a given egress channel.
    + * Note that this may be shared between, say, "gbe0" and "xgbe0".
    + * ISSUE: Defer header allocation until TSO is actually needed?
    + */
    +static int tile_net_init_egress(struct net_device *dev, int echannel)
    +{
    + struct page *headers_page, *edescs_page, *equeue_page;
    + gxio_mpipe_edesc_t *edescs;
    + gxio_mpipe_equeue_t *equeue;
    + unsigned char *headers;
    + int headers_order, edescs_order, equeue_order;
    + size_t edescs_size;
    + int edma;
    + int rc = -ENOMEM;
    +
    + /* Only initialize once. */
    + if (egress_for_echannel[echannel].equeue != NULL)
    + return 0;
    +
    + /* Allocate memory for the "headers". */
    + headers_order = get_order(EQUEUE_ENTRIES * HEADER_BYTES);
    + headers_page = alloc_pages(GFP_KERNEL, headers_order);
    + if (headers_page == NULL) {
    + netdev_warn(dev,
    + "Could not alloc %zd bytes for TSO headers.\n",
    + PAGE_SIZE << headers_order);
    + goto fail;
    + }
    + headers = pfn_to_kaddr(page_to_pfn(headers_page));
    +
    + /* Allocate memory for the "edescs". */
    + edescs_size = EQUEUE_ENTRIES * sizeof(*edescs);
    + edescs_order = get_order(edescs_size);
    + edescs_page = alloc_pages(GFP_KERNEL, edescs_order);
    + if (edescs_page == NULL) {
    + netdev_warn(dev,
    + "Could not alloc %zd bytes for eDMA ring.\n",
    + edescs_size);
    + goto fail_headers;
    + }
    + edescs = pfn_to_kaddr(page_to_pfn(edescs_page));
    +
    + /* Allocate memory for the "equeue". */
    + equeue_order = get_order(sizeof(*equeue));
    + equeue_page = alloc_pages(GFP_KERNEL, equeue_order);
    + if (equeue_page == NULL) {
    + netdev_warn(dev,
    + "Could not alloc %zd bytes for equeue info.\n",
    + PAGE_SIZE << equeue_order);
    + goto fail_edescs;
    + }
    + equeue = pfn_to_kaddr(page_to_pfn(equeue_page));
    +
    + /* Allocate an edma ring. Note that in practice this can't
    + * fail, which is good, because we will leak an edma ring if so.
    + */
    + rc = gxio_mpipe_alloc_edma_rings(&context, 1, 0, 0);
    + if (rc < 0) {
    + netdev_warn(dev, "gxio_mpipe_alloc_edma_rings failed: %d\n",
    + rc);
    + goto fail_equeue;
    + }
    + edma = rc;
    +
    + /* Initialize the equeue. */
    + rc = gxio_mpipe_equeue_init(equeue, &context, edma, echannel,
    + edescs, edescs_size, 0);
    + if (rc != 0) {
    + netdev_err(dev, "gxio_mpipe_equeue_init failed: %d\n", rc);
    + goto fail_equeue;
    + }
    +
    + /* Done. */
    + egress_for_echannel[echannel].equeue = equeue;
    + egress_for_echannel[echannel].headers = headers;
    + return 0;
    +
    +fail_equeue:
    + __free_pages(equeue_page, equeue_order);
    +
    +fail_edescs:
    + __free_pages(edescs_page, edescs_order);
    +
    +fail_headers:
    + __free_pages(headers_page, headers_order);
    +
    +fail:
    + return rc;
    +}
    +
    +/* Return channel number for a newly-opened link. */
    +static int tile_net_link_open(struct net_device *dev, gxio_mpipe_link_t *link,
    + const char *link_name)
    +{
    + int rc = gxio_mpipe_link_open(link, &context, link_name, 0);
    + if (rc < 0) {
    + netdev_err(dev, "Failed to open '%s'\n", link_name);
    + return rc;
    + }
    + rc = gxio_mpipe_link_channel(link);
    + if (rc < 0 || rc >= TILE_NET_CHANNELS) {
    + netdev_err(dev, "gxio_mpipe_link_channel bad value: %d\n", rc);
    + gxio_mpipe_link_close(link);
    + return -EINVAL;
    + }
    + return rc;
    +}
    +
    +/* Help the kernel activate the given network interface. */
    +static int tile_net_open(struct net_device *dev)
    +{
    + struct tile_net_priv *priv = netdev_priv(dev);
    + int rc;
    +
    + mutex_lock(&tile_net_devs_for_channel_mutex);
    +
    + /* Do one-time initialization the first time any device is opened. */
    + if (ingress_irq < 0) {
    + rc = tile_net_init_mpipe(dev);
    + if (rc != 0)
    + goto fail;
    + }
    +
    + /* Determine if this is the "loopify" device. */
    + if (unlikely((loopify_link_name != NULL) &&
    + !strcmp(dev->name, loopify_link_name))) {
    + rc = tile_net_link_open(dev, &priv->link, "loop0");
    + if (rc < 0)
    + goto fail;
    + priv->channel = rc;
    + rc = tile_net_link_open(dev, &priv->loopify_link, "loop1");
    + if (rc < 0)
    + goto fail;
    + priv->loopify_channel = rc;
    + priv->echannel = rc;
    + } else {
    + rc = tile_net_link_open(dev, &priv->link, dev->name);
    + if (rc < 0)
    + goto fail;
    + priv->channel = rc;
    + priv->echannel = rc;
    + }
    +
    + /* Initialize egress info (if needed). Once ever, per echannel. */
    + rc = tile_net_init_egress(dev, priv->echannel);
    + if (rc != 0)
    + goto fail;
    +
    + tile_net_devs_for_channel[priv->channel] = dev;
    +
    + rc = tile_net_update(dev);
    + if (rc != 0)
    + goto fail;
    +
    + mutex_unlock(&tile_net_devs_for_channel_mutex);
    +
    + netif_start_queue(dev);
    + netif_carrier_on(dev);
    + return 0;
    +
    +fail:
    + if (priv->loopify_channel >= 0) {
    + if (gxio_mpipe_link_close(&priv->loopify_link) != 0)
    + netdev_warn(dev, "Failed to close loopify link!\n");
    + priv->loopify_channel = -1;
    + }
    + if (priv->channel >= 0) {
    + if (gxio_mpipe_link_close(&priv->link) != 0)
    + netdev_warn(dev, "Failed to close link!\n");
    + priv->channel = -1;
    + }
    + priv->echannel = -1;
    + tile_net_devs_for_channel[priv->channel] = NULL;
    + mutex_unlock(&tile_net_devs_for_channel_mutex);
    +
    + /* Don't return raw gxio error codes to generic Linux. */
    + return (rc > -512) ? rc : -EIO;
    +}
    +
    +/* Help the kernel deactivate the given network interface. */
    +static int tile_net_stop(struct net_device *dev)
    +{
    + struct tile_net_priv *priv = netdev_priv(dev);
    +
    + netif_stop_queue(dev);
    +
    + mutex_lock(&tile_net_devs_for_channel_mutex);
    + tile_net_devs_for_channel[priv->channel] = NULL;
    + (void)tile_net_update(dev);
    + if (priv->loopify_channel >= 0) {
    + if (gxio_mpipe_link_close(&priv->loopify_link) != 0)
    + netdev_warn(dev, "Failed to close loopify link!\n");
    + priv->loopify_channel = -1;
    + }
    + if (priv->channel >= 0) {
    + if (gxio_mpipe_link_close(&priv->link) != 0)
    + netdev_warn(dev, "Failed to close link!\n");
    + priv->channel = -1;
    + }
    + priv->echannel = -1;
    + mutex_unlock(&tile_net_devs_for_channel_mutex);
    +
    + return 0;
    +}
    +
    +/* Determine the VA for a fragment. */
    +static inline void *tile_net_frag_buf(skb_frag_t *f)
    +{
    + unsigned long pfn = page_to_pfn(skb_frag_page(f));
    + return pfn_to_kaddr(pfn) + f->page_offset;
    +}
    +
    +/* Acquire a completion entry and an egress slot, or if we can't,
    + * stop the queue and schedule the tx_wake timer.
    + */
    +static s64 tile_net_equeue_try_reserve(struct net_device *dev,
    + struct tile_net_comps *comps,
    + gxio_mpipe_equeue_t *equeue,
    + int num_edescs)
    +{
    + /* Try to acquire a completion entry. */
    + if (comps->comp_next - comps->comp_last < TILE_NET_MAX_COMPS - 1 ||
    + tile_net_free_comps(equeue, comps, 32, false) != 0) {
    +
    + /* Try to acquire an egress slot. */
    + s64 slot = gxio_mpipe_equeue_try_reserve(equeue, num_edescs);
    + if (slot >= 0)
    + return slot;
    +
    + /* Freeing some completions gives the equeue time to drain. */
    + tile_net_free_comps(equeue, comps, TILE_NET_MAX_COMPS, false);
    +
    + slot = gxio_mpipe_equeue_try_reserve(equeue, num_edescs);
    + if (slot >= 0)
    + return slot;
    + }
    +
    + /* Still nothing; give up and stop the queue for a short while. */
    + netif_stop_queue(dev);
    + tile_net_schedule_tx_wake_timer(dev);
    + return -1;
    +}
    +
    +/* Determine how many edesc's are needed for TSO.
    + *
    + * Sometimes, if "sendfile()" requires copying, we will be called with
    + * "data" containing the header and payload, with "frags" being empty.
    + * Sometimes, for example when using NFS over TCP, a single segment can
    + * span 3 fragments. This requires special care.
    + */
    +static int tso_count_edescs(struct sk_buff *skb)
    +{
    + struct skb_shared_info *sh = skb_shinfo(skb);
    + unsigned int data_len = skb->data_len;
    + unsigned int p_len = sh->gso_size;
    + long f_id = -1; /* id of the current fragment */
    + long f_size = -1; /* size of the current fragment */
    + long f_used = -1; /* bytes used from the current fragment */
    + long n; /* size of the current piece of payload */
    + int num_edescs = 0;
    + int segment;
    +
    + for (segment = 0; segment < sh->gso_segs; segment++) {
    +
    + unsigned int p_used = 0;
    +
    + /* One edesc for header and for each piece of the payload. */
    + for (num_edescs++; p_used < p_len; num_edescs++) {
    +
    + /* Advance as needed. */
    + while (f_used >= f_size) {
    + f_id++;
    + f_size = sh->frags[f_id].size;
    + f_used = 0;
    + }
    +
    + /* Use bytes from the current fragment. */
    + n = p_len - p_used;
    + if (n > f_size - f_used)
    + n = f_size - f_used;
    + f_used += n;
    + p_used += n;
    + }
    +
    + /* The last segment may be less than gso_size. */
    + data_len -= p_len;
    + if (data_len < p_len)
    + p_len = data_len;
    + }
    +
    + return num_edescs;
    +}
    +
    +/* Prepare modified copies of the skbuff headers.
    + * FIXME: add support for IPv6.
    + */
    +static void tso_headers_prepare(struct sk_buff *skb, unsigned char *headers,
    + s64 slot)
    +{
    + struct skb_shared_info *sh = skb_shinfo(skb);
    + struct iphdr *ih;
    + struct tcphdr *th;
    + unsigned int data_len = skb->data_len;
    + unsigned char *data = skb->data;
    + unsigned int ih_off, th_off, sh_len, p_len;
    + unsigned int isum_seed, tsum_seed, id, seq;
    + long f_id = -1; /* id of the current fragment */
    + long f_size = -1; /* size of the current fragment */
    + long f_used = -1; /* bytes used from the current fragment */
    + long n; /* size of the current piece of payload */
    + int segment;
    +
    + /* Locate original headers and compute various lengths. */
    + ih = ip_hdr(skb);
    + th = tcp_hdr(skb);
    + ih_off = skb_network_offset(skb);
    + th_off = skb_transport_offset(skb);
    + sh_len = th_off + tcp_hdrlen(skb);
    + p_len = sh->gso_size;
    +
    + /* Set up seed values for IP and TCP csum and initialize id and seq. */
    + isum_seed = ((0xFFFF - ih->check) +
    + (0xFFFF - ih->tot_len) +
    + (0xFFFF - ih->id));
    + tsum_seed = th->check + (0xFFFF ^ htons(skb->len));
    + id = ntohs(ih->id);
    + seq = ntohl(th->seq);
    +
    + /* Prepare all the headers. */
    + for (segment = 0; segment < sh->gso_segs; segment++) {
    + unsigned char *buf;
    + unsigned int p_used = 0;
    +
    + /* Copy to the header memory for this segment. */
    + buf = headers + (slot % EQUEUE_ENTRIES) * HEADER_BYTES +
    + NET_IP_ALIGN;
    + memcpy(buf, data, sh_len);
    +
    + /* Update copied ip header. */
    + ih = (struct iphdr *)(buf + ih_off);
    + ih->tot_len = htons(sh_len + p_len - ih_off);
    + ih->id = htons(id);
    + ih->check = csum_long(isum_seed + ih->tot_len +
    + ih->id) ^ 0xffff;
    +
    + /* Update copied tcp header. */
    + th = (struct tcphdr *)(buf + th_off);
    + th->seq = htonl(seq);
    + th->check = csum_long(tsum_seed + htons(sh_len + p_len));
    + if (segment != sh->gso_segs - 1) {
    + th->fin = 0;
    + th->psh = 0;
    + }
    +
    + /* Skip past the header. */
    + slot++;
    +
    + /* Skip past the payload. */
    + while (p_used < p_len) {
    +
    + /* Advance as needed. */
    + while (f_used >= f_size) {
    + f_id++;
    + f_size = sh->frags[f_id].size;
    + f_used = 0;
    + }
    +
    + /* Use bytes from the current fragment. */
    + n = p_len - p_used;
    + if (n > f_size - f_used)
    + n = f_size - f_used;
    + f_used += n;
    + p_used += n;
    +
    + slot++;
    + }
    +
    + id++;
    + seq += p_len;
    +
    + /* The last segment may be less than gso_size. */
    + data_len -= p_len;
    + if (data_len < p_len)
    + p_len = data_len;
    + }
    +
    + /* Flush the headers so they are ready for hardware DMA. */
    + wmb();
    +}
    +
    +/* Pass all the data to mpipe for egress. */
    +static void tso_egress(struct net_device *dev, gxio_mpipe_equeue_t *equeue,
    + struct sk_buff *skb, unsigned char *headers, s64 slot)
    +{
    + struct tile_net_priv *priv = netdev_priv(dev);
    + struct skb_shared_info *sh = skb_shinfo(skb);
    + unsigned int data_len = skb->data_len;
    + unsigned int p_len = sh->gso_size;
    + gxio_mpipe_edesc_t edesc_head = { { 0 } };
    + gxio_mpipe_edesc_t edesc_body = { { 0 } };
    + long f_id = -1; /* id of the current fragment */
    + long f_size = -1; /* size of the current fragment */
    + long f_used = -1; /* bytes used from the current fragment */
    + long n; /* size of the current piece of payload */
    + unsigned long tx_packets = 0, tx_bytes = 0;
    + unsigned int csum_start, sh_len;
    + int segment;
    +
    + /* Prepare to egress the headers: set up header edesc. */
    + csum_start = skb_checksum_start_offset(skb);
    + sh_len = skb_transport_offset(skb) + tcp_hdrlen(skb);
    + edesc_head.csum = 1;
    + edesc_head.csum_start = csum_start;
    + edesc_head.csum_dest = csum_start + skb->csum_offset;
    + edesc_head.xfer_size = sh_len;
    +
    + /* This is only used to specify the TLB. */
    + edesc_head.stack_idx = large_buffer_stack;
    + edesc_body.stack_idx = large_buffer_stack;
    +
    + /* Egress all the edescs. */
    + for (segment = 0; segment < sh->gso_segs; segment++) {
    + void *va;
    + unsigned char *buf;
    + unsigned int p_used = 0;
    +
    + /* Egress the header. */
    + buf = headers + (slot % EQUEUE_ENTRIES) * HEADER_BYTES +
    + NET_IP_ALIGN;
    + edesc_head.va = va_to_tile_io_addr(buf);
    + gxio_mpipe_equeue_put_at(equeue, edesc_head, slot);
    + slot++;
    +
    + /* Egress the payload. */
    + while (p_used < p_len) {
    +
    + /* Advance as needed. */
    + while (f_used >= f_size) {
    + f_id++;
    + f_size = sh->frags[f_id].size;
    + f_used = 0;
    + }
    +
    + va = tile_net_frag_buf(&sh->frags[f_id]) + f_used;
    +
    + /* Use bytes from the current fragment. */
    + n = p_len - p_used;
    + if (n > f_size - f_used)
    + n = f_size - f_used;
    + f_used += n;
    + p_used += n;
    +
    + /* Egress a piece of the payload. */
    + edesc_body.va = va_to_tile_io_addr(va);
    + edesc_body.xfer_size = n;
    + edesc_body.bound = !(p_used < p_len);
    + gxio_mpipe_equeue_put_at(equeue, edesc_body, slot);
    + slot++;
    + }
    +
    + tx_packets++;
    + tx_bytes += sh_len + p_len;
    +
    + /* The last segment may be less than gso_size. */
    + data_len -= p_len;
    + if (data_len < p_len)
    + p_len = data_len;
    + }
    +
    + /* Update stats. */
    + tile_net_stats_add(tx_packets, &priv->stats.tx_packets);
    + tile_net_stats_add(tx_bytes, &priv->stats.tx_bytes);
    +}
    +
    +/* Do "TSO" handling for egress.
    + *
    + * Normally drivers set NETIF_F_TSO only to support hardware TSO;
    + * otherwise the stack uses scatter-gather to implement GSO in software.
    + * On our testing, enabling GSO support (via NETIF_F_SG) drops network
    + * performance down to around 7.5 Gbps on the 10G interfaces, although
    + * also dropping cpu utilization way down, to under 8%. But
    + * implementing "TSO" in the driver brings performance back up to line
    + * rate, while dropping cpu usage even further, to less than 4%. In
    + * practice, profiling of GSO shows that skb_segment() is what causes
    + * the performance overheads; we benefit in the driver from using
    + * preallocated memory to duplicate the TCP/IP headers.
    + */
    +static int tile_net_tx_tso(struct sk_buff *skb, struct net_device *dev)
    +{
    + struct tile_net_priv *priv = netdev_priv(dev);
    + struct tile_net_info *info = &__get_cpu_var(per_cpu_info);
    + int channel = priv->echannel;
    + struct tile_net_egress *egress = &egress_for_echannel[channel];
    + struct tile_net_comps *comps = info->comps_for_echannel[channel];
    + gxio_mpipe_equeue_t *equeue = egress->equeue;
    + unsigned long irqflags;
    + int num_edescs;
    + s64 slot;
    +
    + /* Determine how many mpipe edesc's are needed. */
    + num_edescs = tso_count_edescs(skb);
    +
    + local_irq_save(irqflags);
    +
    + /* Set first reserved egress slot. */
    + slot = tile_net_equeue_try_reserve(dev, comps, equeue, num_edescs);
    + if (slot < 0) {
    + local_irq_restore(irqflags);
    + /* We set the tx_queue_len as 0, so there's no tx packet
    + * enqueuing. We simply drop the packet when the tx queue
    + * is full.
    + */
    + tile_net_stats_add(1, &priv->stats.tx_dropped);
    + return NETDEV_TX_OK;
    + }
    +
    + /* Set up copies of header data properly. */
    + tso_headers_prepare(skb, egress->headers, slot);
    +
    + /* Actually pass the data to the network hardware. */
    + tso_egress(dev, equeue, skb, egress->headers, slot);
    +
    + /* Add a completion record. */
    + add_comp(equeue, comps, slot + num_edescs - 1, skb);
    +
    + local_irq_restore(irqflags);
    +
    + /* Make sure the egress timer is scheduled. */
    + tile_net_schedule_egress_timer(info);
    +
    + return NETDEV_TX_OK;
    +}
    +
    +/* Analyze the body and frags for a transmit request. */
    +static unsigned int tile_net_tx_frags(struct frag *frags,
    + struct sk_buff *skb,
    + void *b_data, unsigned int b_len)
    +{
    + unsigned int i, n = 0;
    +
    + struct skb_shared_info *sh = skb_shinfo(skb);
    +
    + if (b_len != 0) {
    + frags[n].buf = b_data;
    + frags[n++].length = b_len;
    + }
    +
    + for (i = 0; i < sh->nr_frags; i++) {
    + skb_frag_t *f = &sh->frags[i];
    + frags[n].buf = tile_net_frag_buf(f);
    + frags[n++].length = skb_frag_size(f);
    + }
    +
    + return n;
    +}
    +
    +/* Help the kernel transmit a packet. */
    +static int tile_net_tx(struct sk_buff *skb, struct net_device *dev)
    +{
    + struct tile_net_priv *priv = netdev_priv(dev);
    + struct tile_net_info *info = &__get_cpu_var(per_cpu_info);
    + struct tile_net_egress *egress = &egress_for_echannel[priv->echannel];
    + gxio_mpipe_equeue_t *equeue = egress->equeue;
    + struct tile_net_comps *comps =
    + info->comps_for_echannel[priv->echannel];
    + unsigned int len = skb->len;
    + unsigned char *data = skb->data;
    + unsigned int num_edescs;
    + struct frag frags[MAX_FRAGS];
    + gxio_mpipe_edesc_t edescs[MAX_FRAGS];
    + unsigned long irqflags;
    + gxio_mpipe_edesc_t edesc = { { 0 } };
    + unsigned int i;
    + s64 slot;
    +
    + /* Save the timestamp. */
    + dev->trans_start = jiffies;
    +
    + if (skb_is_gso(skb))
    + return tile_net_tx_tso(skb, dev);
    +
    + num_edescs = tile_net_tx_frags(frags, skb, data, skb_headlen(skb));
    +
    + /* This is only used to specify the TLB. */
    + edesc.stack_idx = large_buffer_stack;
    +
    + /* Prepare the edescs. */
    + for (i = 0; i < num_edescs; i++) {
    + edesc.xfer_size = frags[i].length;
    + edesc.va = va_to_tile_io_addr(frags[i].buf);
    + edescs[i] = edesc;
    + }
    +
    + /* Mark the final edesc. */
    + edescs[num_edescs - 1].bound = 1;
    +
    + /* Add checksum info to the initial edesc, if needed. */
    + if (skb->ip_summed == CHECKSUM_PARTIAL) {
    + unsigned int csum_start = skb_checksum_start_offset(skb);
    + edescs[0].csum = 1;
    + edescs[0].csum_start = csum_start;
    + edescs[0].csum_dest = csum_start + skb->csum_offset;
    + }
    +
    + local_irq_save(irqflags);
    +
    + /* Set first reserved egress slot. */
    + slot = tile_net_equeue_try_reserve(dev, comps, equeue, num_edescs);
    + if (slot < 0) {
    + local_irq_restore(irqflags);
    + /* We set the tx_queue_len as 0, so there's no tx packet
    + * enqueuing. We simply drop the packet when the tx queue
    + * is full.
    + */
    + tile_net_stats_add(1, &priv->stats.tx_dropped);
    + return NETDEV_TX_OK;
    + }
    +
    + for (i = 0; i < num_edescs; i++)
    + gxio_mpipe_equeue_put_at(equeue, edescs[i], slot++);
    +
    + /* Add a completion record. */
    + add_comp(equeue, comps, slot - 1, skb);
    +
    + /* NOTE: Use ETH_ZLEN for short packets (e.g. 42 < 60). */
    + tile_net_stats_add(1, &priv->stats.tx_packets);
    + tile_net_stats_add(max_t(unsigned int, len, ETH_ZLEN),
    + &priv->stats.tx_bytes);
    +
    + local_irq_restore(irqflags);
    +
    + /* Make sure the egress timer is scheduled. */
    + tile_net_schedule_egress_timer(info);
    +
    + return NETDEV_TX_OK;
    +}
    +
    +/* Deal with a transmit timeout. */
    +static void tile_net_tx_timeout(struct net_device *dev)
    +{
    + netif_wake_queue(dev);
    +}
    +
    +/* Ioctl commands. */
    +static int tile_net_ioctl(struct net_device *dev, struct ifreq *rq, int cmd)
    +{
    + return -EOPNOTSUPP;
    +}
    +
    +/* Get system network statistics for device. */
    +static struct net_device_stats *tile_net_get_stats(struct net_device *dev)
    +{
    + struct tile_net_priv *priv = netdev_priv(dev);
    + return &priv->stats;
    +}
    +
    +/* Change the MTU. */
    +static int tile_net_change_mtu(struct net_device *dev, int new_mtu)
    +{
    + if ((new_mtu < 68) || (new_mtu > 1500))
    + return -EINVAL;
    + dev->mtu = new_mtu;
    + return 0;
    +}
    +
    +/* Change the Ethernet address of the NIC.
    + *
    + * The hypervisor driver does not support changing MAC address. However,
    + * the hardware does not do anything with the MAC address, so the address
    + * which gets used on outgoing packets, and which is accepted on incoming
    + * packets, is completely up to us.
    + *
    + * Returns 0 on success, negative on failure.
    + */
    +static int tile_net_set_mac_address(struct net_device *dev, void *p)
    +{
    + struct sockaddr *addr = p;
    +
    + if (!is_valid_ether_addr(addr->sa_data))
    + return -EINVAL;
    + memcpy(dev->dev_addr, addr->sa_data, dev->addr_len);
    + return 0;
    +}
    +
    +#ifdef CONFIG_NET_POLL_CONTROLLER
    +/* Polling 'interrupt' - used by things like netconsole to send skbs
    + * without having to re-enable interrupts. It's not called while
    + * the interrupt routine is executing.
    + */
    +static void tile_net_netpoll(struct net_device *dev)
    +{
    + disable_percpu_irq(ingress_irq);
    + tile_net_handle_ingress_irq(ingress_irq, NULL);
    + enable_percpu_irq(ingress_irq, 0);
    +}
    +#endif
    +
    +static const struct net_device_ops tile_net_ops = {
    + .ndo_open = tile_net_open,
    + .ndo_stop = tile_net_stop,
    + .ndo_start_xmit = tile_net_tx,
    + .ndo_do_ioctl = tile_net_ioctl,
    + .ndo_get_stats = tile_net_get_stats,
    + .ndo_change_mtu = tile_net_change_mtu,
    + .ndo_tx_timeout = tile_net_tx_timeout,
    + .ndo_set_mac_address = tile_net_set_mac_address,
    +#ifdef CONFIG_NET_POLL_CONTROLLER
    + .ndo_poll_controller = tile_net_netpoll,
    +#endif
    +};
    +
    +/* The setup function.
    + *
    + * This uses ether_setup() to assign various fields in dev, including
    + * setting IFF_BROADCAST and IFF_MULTICAST, then sets some extra fields.
    + */
    +static void tile_net_setup(struct net_device *dev)
    +{
    + ether_setup(dev);
    + dev->netdev_ops = &tile_net_ops;
    + dev->watchdog_timeo = TILE_NET_TIMEOUT;
    + dev->features |= NETIF_F_LLTX;
    + dev->features |= NETIF_F_HW_CSUM;
    + dev->features |= NETIF_F_SG;
    + dev->features |= NETIF_F_TSO;
    + dev->tx_queue_len = 0;
    + dev->mtu = 1500;
    +}
    +
    +/* Allocate the device structure, register the device, and obtain the
    + * MAC address from the hypervisor.
    + */
    +static void tile_net_dev_init(const char *name, const uint8_t *mac)
    +{
    + int ret;
    + int i;
    + int nz_addr = 0;
    + struct net_device *dev;
    + struct tile_net_priv *priv;
    +
    + /* HACK: Ignore "loop" links. */
    + if (strncmp(name, "loop", 4) == 0)
    + return;
    +
    + /* Allocate the device structure. Normally, "name" is a
    + * template, instantiated by register_netdev(), but not for us.
    + */
    + dev = alloc_netdev(sizeof(*priv), name, tile_net_setup);
    + if (!dev) {
    + pr_err("alloc_netdev(%s) failed\n", name);
    + return;
    + }
    +
    + /* Initialize "priv". */
    + priv = netdev_priv(dev);
    + memset(priv, 0, sizeof(*priv));
    + priv->dev = dev;
    + priv->channel = -1;
    + priv->loopify_channel = -1;
    + priv->echannel = -1;
    +
    + /* Get the MAC address and set it in the device struct; this must
    + * be done before the device is opened. If the MAC is all zeroes,
    + * we use a random address, since we're probably on the simulator.
    + */
    + for (i = 0; i < 6; i++)
    + nz_addr |= mac[i];
    +
    + if (nz_addr) {
    + memcpy(dev->dev_addr, mac, 6);
    + dev->addr_len = 6;
    + } else {
    + random_ether_addr(dev->dev_addr);
    + }
    +
    + /* Initialize the transmit wake timer. */
    + hrtimer_init(&priv->tx_wake_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
    + priv->tx_wake_timer.function = tile_net_handle_tx_wake_timer;
    +
    + /* Register the network device. */
    + ret = register_netdev(dev);
    + if (ret) {
    + netdev_err(dev, "register_netdev failed %d\n", ret);
    + free_netdev(dev);
    + return;
    + }
    +}
    +
    +/* Per-cpu module initialization. */
    +static void tile_net_init_module_percpu(void *unused)
    +{
    + struct tile_net_info *info = &__get_cpu_var(per_cpu_info);
    + int my_cpu = smp_processor_id();
    +
    + info->has_iqueue = false;
    +
    + info->my_cpu = my_cpu;
    +
    + /* Initialize the egress timer. */
    + hrtimer_init(&info->egress_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
    + info->egress_timer.function = tile_net_handle_egress_timer;
    +}
    +
    +/* Module initialization. */
    +static int __init tile_net_init_module(void)
    +{
    + int i;
    + char name[GXIO_MPIPE_LINK_NAME_LEN];
    + uint8_t mac[6];
    +
    + pr_info("Tilera Network Driver\n");
    +
    + mutex_init(&tile_net_devs_for_channel_mutex);
    +
    + /* Initialize each CPU. */
    + on_each_cpu(tile_net_init_module_percpu, NULL, 1);
    +
    + /* Find out what devices we have, and initialize them. */
    + for (i = 0; gxio_mpipe_link_enumerate_mac(i, name, mac) >= 0; i++)
    + tile_net_dev_init(name, mac);
    +
    + if (!network_cpus_init())
    + network_cpus_map = *cpu_online_mask;
    +
    + return 0;
    +}
    +
    +module_init(tile_net_init_module);
    --
    1.6.5.2


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