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SubjectRE: [PATCH RESEND 1/2] dmaengine: added MIC X200 Coprocessor DMA driver
Date
Hi Andy, Vinod,

Thanks for your reviews. I will go with Andy's suggestion and rewrite
the driver using virt-dma api. This will also solve the locking problem that
Vinod has pointed out. I will post the next version after the rewrite and
it will also include fixes for the rest of your comments.

Regarding x100_dma reuse: it would be really hard because x200 is not an
evolution of x100, it's a different HW. X200 has its own PCIID, has different
MMIO registers, descriptor format and so on.

Regards,
Jacek

> -----Original Message-----
> From: Andy Shevchenko [mailto:andy.shevchenko@gmail.com]
> Sent: Thursday, February 4, 2016 6:51 PM
> To: Lawrynowicz, Jacek <jacek.lawrynowicz@intel.com>
> Cc: Williams, Dan J <dan.j.williams@intel.com>; Koul, Vinod
> <vinod.koul@intel.com>; dmaengine <dmaengine@vger.kernel.org>; linux-
> kernel@vger.kernel.org; Dixit, Ashutosh <ashutosh.dixit@intel.com>; Dutt,
> Sudeep <sudeep.dutt@intel.com>; Kacprowski, Andrzej
> <Andrzej.Kacprowski@intel.com>
> Subject: Re: [PATCH RESEND 1/2] dmaengine: added MIC X200 Coprocessor DMA
> driver
>
> On Thu, Feb 4, 2016 at 5:10 PM, Jacek Lawrynowicz
> <jacek.lawrynowicz@intel.com> wrote:
> > This patch implements the DMA Engine driver for the DMA controller on
> > MIC X200 Coprocessors which are PCIe cards running Linux. Separate but
> > identical DMA channels are available for the host and card. DMA
> > transfers can be done from both the host and card in host<->card and
> > host<->host directions.
> >
>
> Can it share code with 100 series?
>
> > Signed-off-by: Jacek Lawrynowicz <jacek.lawrynowicz@intel.com>
> > Signed-off-by: Sudeep Dutt <sudeep.dutt@intel.com>
> > Signed-off-by: Ashutosh Dixit <ashutosh.dixit@intel.com>
> > Signed-off-by: Andrzej Kacprowski <andrzej.kacprowski@intel.com>
> > ---
> > drivers/dma/Kconfig | 18 +
> > drivers/dma/Makefile | 1 +
> > drivers/dma/mic_x200_dma.c | 1114
> ++++++++++++++++++++++++++++++++++++++++++++
> > 3 files changed, 1133 insertions(+)
> > create mode 100644 drivers/dma/mic_x200_dma.c
> >
> > diff --git a/drivers/dma/Kconfig b/drivers/dma/Kconfig
> > index 79b1390..a3ea8b9 100644
> > --- a/drivers/dma/Kconfig
> > +++ b/drivers/dma/Kconfig
> > @@ -277,6 +277,24 @@ config INTEL_MIC_X100_DMA
> > OS and tools for MIC to use with this driver are available from
> > <http://software.intel.com/en-us/mic-developer>.
> >
> > +config INTEL_MIC_X200_DMA
> > + tristate "Intel MIC X200 DMA Driver"
> > + depends on 64BIT && X86 && PCI
>
> Doesn't it the same like
> depends on X86_64 && PCI
> ?
>
> > + select DMAENGINE
> > + help
> > + This enables DMA support for the Intel Many Integrated Core
> > + (MIC) family of PCIe form factor coprocessor X200 devices that
> > + run a 64 bit Linux OS. This driver will be used by both MIC
> > + host and card drivers.
> > +
> > + If you are building host kernel with a MIC device or a card
> > + kernel for a MIC device, then say M (recommended) or Y, else
> > + say N. If unsure say N.
> > +
> > + More information about the Intel MIC family as well as the Linux
> > + OS and tools for MIC to use with this driver are available from
> > + <http://software.intel.com/en-us/mic-developer>.
> > +
> > config K3_DMA
> > tristate "Hisilicon K3 DMA support"
> > depends on ARCH_HI3xxx
> > diff --git a/drivers/dma/Makefile b/drivers/dma/Makefile
> > index 2dd0a067..a3756f5 100644
> > --- a/drivers/dma/Makefile
> > +++ b/drivers/dma/Makefile
> > @@ -38,6 +38,7 @@ obj-$(CONFIG_INTEL_IDMA64) += idma64.o
> > obj-$(CONFIG_INTEL_IOATDMA) += ioat/
> > obj-$(CONFIG_INTEL_IOP_ADMA) += iop-adma.o
> > obj-$(CONFIG_INTEL_MIC_X100_DMA) += mic_x100_dma.o
> > +obj-$(CONFIG_INTEL_MIC_X200_DMA) += mic_x200_dma.o
> > obj-$(CONFIG_K3_DMA) += k3dma.o
> > obj-$(CONFIG_LPC18XX_DMAMUX) += lpc18xx-dmamux.o
> > obj-$(CONFIG_MMP_PDMA) += mmp_pdma.o
> > diff --git a/drivers/dma/mic_x200_dma.c b/drivers/dma/mic_x200_dma.c
> > new file mode 100644
> > index 0000000..80c4959
> > --- /dev/null
> > +++ b/drivers/dma/mic_x200_dma.c
> > @@ -0,0 +1,1114 @@
> > +/*
> > + * Intel MIC Platform Software Stack (MPSS)
> > + *
> > + * Copyright(c) 2016 Intel Corporation.
> > + *
> > + * This program is free software; you can redistribute it and/or modify
> > + * it under the terms of the GNU General Public License, version 2, as
> > + * published by the Free Software Foundation.
> > + *
> > + * 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. See the GNU
> > + * General Public License for more details.
> > + *
> > + * The full GNU General Public License is included in this distribution in
> > + * the file called "COPYING".
> > + *
> > + * Intel MIC X200 DMA driver
> > + */
> > +#include <linux/module.h>
> > +#include <linux/delay.h>
> > +#include <linux/pci.h>
> > +#include <linux/interrupt.h>
> > +#include <linux/vmalloc.h>
> > +
> > +#include "dmaengine.h"
> > +
> > +#define MIC_DMA_DRV_NAME "mic_x200_dma"
> > +
> > +#define MIC_DMA_DESC_RX_SIZE (128 * 1024)
> > +#define MIC_DMA_ABORT_TO_MS 3000
> > +#define MIC_DMA_RING_TO_MS 20
> > +#define MIC_DMA_PENDING_LEVEL 16
> > +#define MIC_DMA_ABORT_LIMIT 5
> > +
> > +/* DMA Descriptor related flags */
> > +#define MIC_DMA_DESC_VALID BIT(31)
> > +#define MIC_DMA_DESC_INTR_ENABLE BIT(30)
> > +#define MIC_DMA_DESC_SRC_LINK_ERR BIT(29)
> > +#define MIC_DMA_DESC_DST_LINK_ERR BIT(28)
> > +#define MIC_DMA_DESC_LOW_MASK (0xffffffffUL)
> > +#define MIC_DMA_DESC_SRC_LOW_SHIFT 32
> > +#define MIC_DMA_DESC_BITS_32_TO_47 (0xffffUL << 32)
> > +#define MIC_DMA_DESC_SIZE_MASK ((1UL << 27) - 1)
> > +
> > +#define MIC_DMA_DESC_RING_ADDR_LOW 0x214
> > +#define MIC_DMA_DESC_RING_ADDR_HIGH 0x218
> > +#define MIC_DMA_NEXT_DESC_ADDR_LOW 0x21C
> > +#define MIC_DMA_DESC_RING_SIZE 0x220
> > +#define MIC_DMA_LAST_DESC_ADDR_LOW 0x224
> > +#define MIC_DMA_LAST_DESC_XFER_SIZE 0x228
> > +
> > +#define MIC_DMA_CTRL_STATUS 0x238
> > +#define MIC_DMA_CTRL_PAUSE BIT(0)
> > +#define MIC_DMA_CTRL_ABORT BIT(1)
> > +#define MIC_DMA_CTRL_WB_ENABLE BIT(2)
> > +#define MIC_DMA_CTRL_START BIT(3)
> > +#define MIC_DMA_CTRL_RING_STOP BIT(4)
> > +#define MIC_DMA_CTRL_ONCHIP_MODE BIT(5)
> > +#define MIC_DMA_CTRL_OFFCHIP_MODE (2UL << 5)
> > +#define MIC_DMA_CTRL_DESC_INVLD_STATUS BIT(8)
> > +#define MIC_DMA_CTRL_PAUSE_DONE_STATUS BIT(9)
> > +#define MIC_DMA_CTRL_ABORT_DONE_STATUS BIT(10)
> > +#define MIC_DMA_CTRL_FACTORY_TEST BIT(11)
> > +#define MIC_DMA_CTRL_IMM_PAUSE_DONE_STATUS BIT(12)
> > +#define MIC_DMA_CTRL_SRC_MAX_TRANSFER_SIZE (3UL << 16)
> > +#define MIC_DMA_CTRL_RELAXED_DATA_WRITE BIT(25)
> > +#define MIC_DMA_CTRL_NO_SNOOP_DESC_READ BIT(26)
> > +#define MIC_DMA_CTRL_NO_SNOOP_DATA_READ BIT(27)
> > +#define MIC_DMA_CTRL_NO_SNOOP_DESC_WRITE BIT(28)
> > +#define MIC_DMA_CTRL_IN_PROGRESS BIT(30)
> > +#define MIC_DMA_CTRL_HEADER_LOG BIT(31)
> > +#define MIC_DMA_CTRL_MODE_BITS (3UL << 5)
> > +#define MIC_DMA_CTRL_STATUS_BITS (0x1FUL << 8)
> > +#define MIC_DMA_CTRL_STATUS_INIT
> (MIC_DMA_CTRL_SRC_MAX_TRANSFER_SIZE | \
> > + MIC_DMA_CTRL_RELAXED_DATA_WRITE | \
> > + MIC_DMA_CTRL_NO_SNOOP_DESC_READ | \
> > + MIC_DMA_CTRL_NO_SNOOP_DATA_READ | \
> > + MIC_DMA_CTRL_NO_SNOOP_DESC_WRITE)
> > +
> > +#define MIC_DMA_INTR_CTRL_STATUS 0x23C
> > +#define MIC_DMA_ERROR_INTR_EN BIT(0)
> > +#define MIC_DMA_INVLD_DESC_INTR_EN BIT(1)
> > +#define MIC_DMA_ABORT_DONE_INTR_EN BIT(3)
> > +#define MIC_DMA_GRACE_PAUSE_INTR_EN BIT(4)
> > +#define MIC_DMA_IMM_PAUSE_INTR_EN BIT(5)
> > +#define MIC_DMA_IRQ_PIN_INTR_EN BIT(15)
> > +#define MIC_DMA_ERROR_INTR_STATUS BIT(16)
> > +#define MIC_DMA_INVLD_DESC_INTR_STATUS BIT(17)
> > +#define MIC_DMA_DESC_DONE_INTR_STATUS BIT(18)
> > +#define MIC_DMA_ABORT_DONE_INTR_STATUS BIT(19)
> > +#define MIC_DMA_GRACE_PAUSE_INTR_STATUS BIT(20)
> > +#define MIC_DMA_IMM_PAUSE_INTR_STATUS BIT(21)
> > +#define MIC_DMA_ALL_INTR_EN (MIC_DMA_ERROR_INTR_EN | \
> > + MIC_DMA_INVLD_DESC_INTR_EN | \
> > + MIC_DMA_ABORT_DONE_INTR_EN | \
> > + MIC_DMA_GRACE_PAUSE_INTR_EN | \
> > + MIC_DMA_IMM_PAUSE_INTR_EN)
> > +
> > +#define MIC_DMA_ERROR_STATUS (MIC_DMA_ERROR_INTR_STATUS |
> \
> > + MIC_DMA_ABORT_DONE_INTR_STATUS | \
> > + MIC_DMA_GRACE_PAUSE_INTR_STATUS | \
> > + MIC_DMA_IMM_PAUSE_INTR_STATUS)
> > +
> > +#define MIC_DMA_ALL_INTR_STATUS (MIC_DMA_ERROR_INTR_STATUS
> | \
> > + MIC_DMA_INVLD_DESC_INTR_STATUS | \
> > + MIC_DMA_DESC_DONE_INTR_STATUS | \
> > + MIC_DMA_ABORT_DONE_INTR_STATUS | \
> > + MIC_DMA_GRACE_PAUSE_INTR_STATUS | \
> > + MIC_DMA_IMM_PAUSE_INTR_STATUS)
> > +/*
> > + * Performance tuning registers. For explanation of the values
> > + * used please refer to mic x200 dma hardware specification.
> > + */
> > +#define MIC_DMA_CHAN_BANDWIDTH 0x22C
> > +#define MIC_DMA_MAX_DST_MEM_WRITE (2 << 24)
> > +
> > +#define MIC_DMA_STA_RAM_THRESH 0x258
> > +#define MIC_DMA_HDR_RAM_USAGE_THRESH 46UL
> > +#define MIC_DMA_PLD_RAM_USAGE_THRESH (61UL << 16)
> > +#define MIC_DMA_STA_RAM_THRESH_INIT
> (MIC_DMA_HDR_RAM_USAGE_THRESH | \
> > + MIC_DMA_PLD_RAM_USAGE_THRESH)
> > +
> > +#define MIC_DMA_STA0_HDR_RAM 0x25C
> > +#define MIC_DMA_STA1_HDR_RAM 0x2A4
> > +#define MIC_DMA_HDR_RAM_UPPER_THRESH 160UL
> > +#define MIC_DMA_HDR_RAM_LOWER_THRESH (152UL << 16)
> > +#define MIC_DMA_STA_HDR_THRESH_INIT
> (MIC_DMA_HDR_RAM_UPPER_THRESH | \
> > + MIC_DMA_HDR_RAM_LOWER_THRESH)
> > +
> > +#define MIC_DMA_STA0_PLD_RAM 0x260
> > +#define MIC_DMA_STA1_PLD_RAM 0x2A8
> > +#define MIC_DMA_PLD_RAM_UPPER_THRESH 256UL
> > +#define MIC_DMA_PLD_RAM_LOWER_THRESH (248UL << 16)
> > +#define MIC_DMA_STA_PLD_THRESH_INIT
> (MIC_DMA_PLD_RAM_UPPER_THRESH | \
> > + MIC_DMA_PLD_RAM_LOWER_THRESH)
> > +
> > +/* HW DMA descriptor */
> > +struct mic_dma_desc {
> > + u64 qw0;
> > + u64 qw1;
> > +};
> > +
> > +/*
> > + * mic_dma_chan - MIC X200 DMA channel specific data structures
> > + *
> > + * @ch_num: channel number
> > + * @last_tail: cached value of descriptor ring tail
> > + * @head: index of next descriptor in desc_ring
> > + * @chan: dma engine api channel
> > + * @desc_ring: dma descriptor ring
> > + * @desc_ring_da: DMA address of desc_ring
> > + * @tx_array: array of async_tx
> > + * @cleanup_lock: used to synchronize descriptor cleanup
> > + * @prep_lock: lock held in prep_memcpy & released in tx_submit
> > + * @issue_lock: lock used to synchronize writes to head
> > + * @notify_hw: flag used to notify HW that new descriptors are available
> > + * @abort_tail: descriptor ring position at which last abort occurred
> > + * @abort_counter: number of aborts at the last position in desc ring
> > + */
> > +struct mic_dma_chan {
> > + int ch_num;
> > + u32 last_tail;
> > + u32 head;
>
> > + struct dma_chan chan;
> > + struct mic_dma_desc *desc_ring;
> > + dma_addr_t desc_ring_da;
> > + struct dma_async_tx_descriptor *tx_array;
>
> Btw, can you use virt-chan API?
>
> > + spinlock_t cleanup_lock;
> > + spinlock_t prep_lock;
> > + spinlock_t issue_lock;
> > + bool notify_hw;
> > + u32 abort_tail;
> > + u32 abort_counter;
> > +};
> > +
> > +/*
> > + * mic_dma_device - Per MIC X200 DMA device driver specific data structures
> > + *
> > + * @pdev: PCIe device
> > + * @dma_dev: underlying dma device
> > + * @reg_base: virtual address of the mmio space
> > + * @mic_chan: Array of MIC X200 DMA channels
> > + * @max_xfer_size: maximum transfer size per dma descriptor
> > + */
> > +struct mic_dma_device {
> > + struct pci_dev *pdev;
> > + struct dma_device dma_dev;
> > + void __iomem *reg_base;
> > + struct mic_dma_chan mic_chan;
> > + size_t max_xfer_size;
> > +};
> > +
> > +static inline struct mic_dma_device *to_mic_dma_dev(struct mic_dma_chan
> *ch)
> > +{
> > + return
> > + container_of((const typeof(((struct mic_dma_device *)0)->mic_chan) *)
> > + (ch - ch->ch_num), struct mic_dma_device, mic_chan);
> > +}
> > +
> > +static inline struct mic_dma_chan *to_mic_dma_chan(struct dma_chan *ch)
> > +{
> > + return container_of(ch, struct mic_dma_chan, chan);
> > +}
> > +
> > +static inline struct device *mic_dma_ch_to_device(struct mic_dma_chan *ch)
> > +{
> > + return to_mic_dma_dev(ch)->dma_dev.dev;
> > +}
> > +
> > +static inline u32 mic_dma_reg_read(struct mic_dma_device *pdma, u32
> offset)
> > +{
> > + return ioread32(pdma->reg_base + offset);
> > +}
> > +
> > +static inline void mic_dma_reg_write(struct mic_dma_device *pdma,
> > + u32 offset, u32 value)
> > +{
> > + iowrite32(value, pdma->reg_base + offset);
> > +}
> > +
> > +static inline u32 mic_dma_ch_reg_read(struct mic_dma_chan *ch, u32 offset)
> > +{
> > + return mic_dma_reg_read(to_mic_dma_dev(ch), offset);
> > +}
> > +
> > +static inline void mic_dma_ch_reg_write(struct mic_dma_chan *ch,
> > + u32 offset, u32 value)
> > +{
> > + mic_dma_reg_write(to_mic_dma_dev(ch), offset, value);
> > +}
> > +
> > +static inline u32 mic_dma_ring_inc(u32 val)
> > +{
> > + return (val + 1) & (MIC_DMA_DESC_RX_SIZE - 1);
>
> return (val + 1) % MIC_DMA_DESC_RX_SIZE;
>
> More flexible, if the size is power of 2 it will be optimized by
> compiler to the same you had previously.
>
> > +}
> > +
> > +static inline u32 mic_dma_ring_dec(u32 val)
> > +{
> > + return val ? val - 1 : MIC_DMA_DESC_RX_SIZE - 1;
>
> return (val - 1) % MIC_DMA_DESC_RX_SIZE;
>
> Would it be issues with that?
>
> > +}
> > +
> > +static inline void mic_dma_inc_head(struct mic_dma_chan *ch)
> > +{
> > + ch->head = mic_dma_ring_inc(ch->head);
> > +}
> > +
> > +static int mic_dma_alloc_desc_ring(struct mic_dma_chan *ch)
> > +{
> > + /* Desc size must be >= depth of ring + prefetch size + 1 */
> > + u64 desc_ring_size = MIC_DMA_DESC_RX_SIZE * sizeof(*ch->desc_ring);
> > + struct device *dev = to_mic_dma_dev(ch)->dma_dev.dev;
> > +
> > + ch->desc_ring = dma_alloc_coherent(dev, desc_ring_size,
> > + &ch->desc_ring_da,
> > + GFP_KERNEL | __GFP_ZERO);
> > + if (!ch->desc_ring)
> > + return -ENOMEM;
> > +
> > + dev_dbg(dev, "DMA desc ring VA = %p DA 0x%llx size 0x%llx\n",
> > + ch->desc_ring, ch->desc_ring_da, desc_ring_size);
>
> %pad for DMA addresses.
>
> > + ch->tx_array = vzalloc(MIC_DMA_DESC_RX_SIZE * sizeof(*ch->tx_array));
>
> > + if (!ch->tx_array)
> > + goto tx_error;
> > + return 0;
>
> > +tx_error:
> > + dma_free_coherent(dev, desc_ring_size, ch->desc_ring, ch-
> >desc_ring_da);
> > + return -ENOMEM;
>
> Only one user, may be you can move it there?
>
> > +}
> > +
> > +static inline void mic_dma_disable_chan(struct mic_dma_chan *ch)
> > +{
> > + struct device *dev = mic_dma_ch_to_device(ch);
> > + u32 ctrl_reg = mic_dma_ch_reg_read(ch, MIC_DMA_CTRL_STATUS);
>
> > + int i;
>
> unsigned int i;
>
> > +
> > + /* set abort bit and clear start bit */
> > + ctrl_reg |= MIC_DMA_CTRL_ABORT;
> > + ctrl_reg &= ~MIC_DMA_CTRL_START;
> > + mic_dma_ch_reg_write(ch, MIC_DMA_CTRL_STATUS, ctrl_reg);
> > +
> > + for (i = 0; i < MIC_DMA_ABORT_TO_MS; i++) {
> > + ctrl_reg = mic_dma_ch_reg_read(ch, MIC_DMA_CTRL_STATUS);
> > +
> > + if (ctrl_reg & MIC_DMA_CTRL_ABORT_DONE_STATUS)
> > + return;
> > +
> > + mdelay(1);
> > + }
> > + dev_err(dev, "%s abort timed out 0x%x head %d tail %d\n",
> > + __func__, ctrl_reg, ch->head, ch->last_tail);
> > +}
> > +
> > +static inline void mic_dma_enable_chan(struct mic_dma_chan *ch)
> > +{
> > + u32 ctrl_reg = mic_dma_ch_reg_read(ch, MIC_DMA_CTRL_STATUS);
> > +
> > + ctrl_reg |= MIC_DMA_CTRL_WB_ENABLE;
> > + /* Clear any active status bits ([31,12:8]) */
> > + ctrl_reg |= MIC_DMA_CTRL_HEADER_LOG |
> MIC_DMA_CTRL_STATUS_BITS;
> > + ctrl_reg &= ~MIC_DMA_CTRL_MODE_BITS;
> > + /* Enable SGL off-chip mode */
> > + ctrl_reg |= MIC_DMA_CTRL_OFFCHIP_MODE;
> > + /* Set start and clear abort and abort done bits */
> > + ctrl_reg |= MIC_DMA_CTRL_START;
> > + ctrl_reg &= ~MIC_DMA_CTRL_ABORT;
> > + mic_dma_ch_reg_write(ch, MIC_DMA_CTRL_STATUS, ctrl_reg);
> > +}
> > +
> > +static inline void mic_dma_chan_mask_intr(struct mic_dma_chan *ch)
> > +{
> > + u32 intr_reg = mic_dma_ch_reg_read(ch,
> MIC_DMA_INTR_CTRL_STATUS);
> > +
> > + intr_reg &= ~(MIC_DMA_ALL_INTR_EN);
>
> Redundant parens.
>
> > + mic_dma_ch_reg_write(ch, MIC_DMA_INTR_CTRL_STATUS, intr_reg);
> > +}
> > +
> > +static inline void mic_dma_chan_unmask_intr(struct mic_dma_chan *ch)
> > +{
> > + u32 intr_reg = mic_dma_ch_reg_read(ch,
> MIC_DMA_INTR_CTRL_STATUS);
> > +
> > + intr_reg |= (MIC_DMA_ALL_INTR_EN);
>
> Ditto
>
> > + mic_dma_ch_reg_write(ch, MIC_DMA_INTR_CTRL_STATUS, intr_reg);
> > +}
> > +
> > +static void mic_dma_chan_set_desc_ring(struct mic_dma_chan *ch)
> > +{
> > + /* Set up the descriptor ring base address and size */
>
> > + mic_dma_ch_reg_write(ch, MIC_DMA_DESC_RING_ADDR_LOW,
> > + ch->desc_ring_da & 0xffffffff);
> > + mic_dma_ch_reg_write(ch, MIC_DMA_DESC_RING_ADDR_HIGH,
> > + (ch->desc_ring_da >> 32) & 0xffffffff);
>
> Better to provide mic_dma_ch_reg_writeq() based on lo_hi_writel().
>
> > + mic_dma_ch_reg_write(ch, MIC_DMA_DESC_RING_SIZE,
> MIC_DMA_DESC_RX_SIZE);
>
> > + /* Set up the next descriptor to the base of the descriptor ring */
> > + mic_dma_ch_reg_write(ch, MIC_DMA_NEXT_DESC_ADDR_LOW,
> > + ch->desc_ring_da & 0xffffffff);
>
> Only low?
>
> > +}
> > +
> > +static void mic_dma_cleanup(struct mic_dma_chan *ch)
> > +{
> > + struct dma_async_tx_descriptor *tx;
> > + u32 last_tail;
> > + u32 cached_head;
> > +
> > + spin_lock(&ch->cleanup_lock);
> > + /*
> > + * Use a cached head rather than using ch->head directly, since a
> > + * different thread can be updating ch->head potentially leading to an
> > + * infinite loop below.
> > + */
> > + cached_head = ACCESS_ONCE(ch->head);
> > + /*
> > + * This is the barrier pair for smp_wmb() in fn.
> > + * mic_dma_tx_submit_unlock. It's required so that we read the
> > + * updated cookie value from tx->cookie.
> > + */
> > + smp_rmb();
> > +
> > + for (last_tail = ch->last_tail; last_tail != cached_head;) {
> > + /* Break out of the loop if this desc is not yet complete */
> > + if (ch->desc_ring[last_tail].qw0 & MIC_DMA_DESC_VALID)
> > + break;
> > +
> > + tx = &ch->tx_array[last_tail];
> > + if (tx->cookie) {
> > + dma_cookie_complete(tx);
> > + if (tx->callback) {
> > + tx->callback(tx->callback_param);
> > + tx->callback = NULL;
> > + }
> > + }
> > + last_tail = mic_dma_ring_inc(last_tail);
> > + }
> > + /* finish all completion callbacks before incrementing tail */
> > + smp_mb();
> > + ch->last_tail = last_tail;
> > + spin_unlock(&ch->cleanup_lock);
> > +}
> > +
> > +static int mic_dma_chan_setup(struct mic_dma_chan *ch)
> > +{
> > + mic_dma_chan_set_desc_ring(ch);
> > + ch->last_tail = 0;
> > + ch->head = 0;
> > + ch->notify_hw = 1;
>
> > + mic_dma_chan_unmask_intr(ch);
> > + mic_dma_enable_chan(ch);
>
> Seems alogical. Perhaps first is to enable channel and then enable interrupts?
>
> > + return 0;
> > +}
> > +
> > +static void mic_dma_free_desc_ring(struct mic_dma_chan *ch)
> > +{
> > + u64 desc_ring_size = MIC_DMA_DESC_RX_SIZE * sizeof(*ch->desc_ring);
> > + struct device *dev = to_mic_dma_dev(ch)->dma_dev.dev;
> > +
> > + vfree(ch->tx_array);
> > + dma_free_coherent(dev, desc_ring_size, ch->desc_ring, ch-
> >desc_ring_da);
> > + ch->desc_ring = NULL;
> > + ch->desc_ring_da = 0;
> > +
> > + /* Reset description ring registers */
> > + mic_dma_chan_set_desc_ring(ch);
> > +}
> > +
> > +static int mic_dma_chan_init(struct mic_dma_chan *ch)
> > +{
> > + struct device *dev = mic_dma_ch_to_device(ch);
> > + int rc;
> > +
> > + rc = mic_dma_alloc_desc_ring(ch);
> > + if (rc)
> > + goto ring_error;
> > + rc = mic_dma_chan_setup(ch);
> > + if (rc)
> > + goto chan_error;
> > + return rc;
> > +chan_error:
> > + mic_dma_free_desc_ring(ch);
>
> > +ring_error:
> > + dev_err(dev, "%s ret %d\n", __func__, rc);
>
> Is it useful?
>
> > + return rc;
> > +}
> > +
> > +static int mic_dma_alloc_chan_resources(struct dma_chan *ch)
> > +{
> > + struct mic_dma_chan *mic_ch = to_mic_dma_chan(ch);
> > + struct device *dev = mic_dma_ch_to_device(mic_ch);
> > + int rc = mic_dma_chan_init(mic_ch);
> > +
> > + if (rc) {
> > + dev_err(dev, "%s ret %d\n", __func__, rc);
>
> Ditto.
>
> > + return rc;
> > + }
> > + return MIC_DMA_DESC_RX_SIZE;
> > +}
> > +
> > +static inline u32 desc_ring_da_to_index(struct mic_dma_chan *ch, u32 descr)
> > +{
> > + dma_addr_t last_dma_off = descr - (ch->desc_ring_da & ULONG_MAX);
>
> Hmm… Why do you need that strange masking?
>
> > +
> > + return (last_dma_off / sizeof(struct mic_dma_desc)) &
> > + (MIC_DMA_DESC_RX_SIZE - 1);
>
> % _RX_SIZE
>
> > +}
> > +
> > +static inline u32 desc_ring_index_to_da(struct mic_dma_chan *ch, u32 index)
> > +{
> > + dma_addr_t addr = ch->desc_ring_da +
> > + sizeof(struct mic_dma_desc) * index;
> > +
> > + return (addr & ULONG_MAX);
> > +}
> > +
> > +static void mic_dma_free_chan_resources(struct dma_chan *ch)
> > +{
> > + struct mic_dma_chan *mic_ch = to_mic_dma_chan(ch);
> > +
> > + mic_dma_disable_chan(mic_ch);
> > + mic_dma_chan_mask_intr(mic_ch);
> > + mic_dma_cleanup(mic_ch);
> > + mic_dma_free_desc_ring(mic_ch);
> > +}
> > +
> > +static enum dma_status
> > +mic_dma_tx_status(struct dma_chan *ch, dma_cookie_t cookie,
> > + struct dma_tx_state *txstate)
> > +{
> > + struct mic_dma_chan *mic_ch = to_mic_dma_chan(ch);
> > +
> > + if (dma_cookie_status(ch, cookie, txstate) != DMA_COMPLETE)
> > + mic_dma_cleanup(mic_ch);
> > +
> > + return dma_cookie_status(ch, cookie, txstate);
> > +}
> > +
> > +static int mic_dma_ring_count(u32 head, u32 tail)
> > +{
> > + int count;
> > +
> > + if (head >= tail)
> > + count = (tail - 0) + (MIC_DMA_DESC_RX_SIZE - head);
> > + else
> > + count = tail - head;
> > + return count - 1;
> > +}
> > +
> > +static int mic_dma_avail_desc_ring_space(struct mic_dma_chan *ch, int
> required)
> > +{
> > + struct device *dev = mic_dma_ch_to_device(ch);
> > + int count;
> > + unsigned long timeout = jiffies +
> > + msecs_to_jiffies(MIC_DMA_RING_TO_MS);
> > +
> > + count = mic_dma_ring_count(ch->head, ch->last_tail);
> > + while (count < required) {
> > + mic_dma_cleanup(ch);
> > + count = mic_dma_ring_count(ch->head, ch->last_tail);
> > + if ((count >= required) || time_after_eq(jiffies, timeout))
> > + break;
> > + usleep_range(50, 100);
> > + }
> > +
> > + if (count < required) {
> > + dev_err(dev, "%s count %d reqd %d head %d tail %d\n",
> > + __func__, count, required, ch->head, ch->last_tail);
> > + return -ENOMEM;
> > + }
> > + return count;
> > +}
> > +
> > +static void
> > +mic_dma_memcpy_desc(struct mic_dma_desc *desc, dma_addr_t src_phys,
> > + dma_addr_t dst_phys, u64 size, int flags)
> > +{
> > + u64 qw0, qw1;
> > +
> > + qw0 = (src_phys & MIC_DMA_DESC_BITS_32_TO_47) << 16;
> > + qw0 |= (dst_phys & MIC_DMA_DESC_BITS_32_TO_47);
> > + qw0 |= size & MIC_DMA_DESC_SIZE_MASK;
> > + qw0 |= MIC_DMA_DESC_VALID;
> > + if (flags & DMA_PREP_INTERRUPT)
> > + qw0 |= MIC_DMA_DESC_INTR_ENABLE;
> > +
> > + qw1 = (src_phys & MIC_DMA_DESC_LOW_MASK) <<
> MIC_DMA_DESC_SRC_LOW_SHIFT;
> > + qw1 |= dst_phys & MIC_DMA_DESC_LOW_MASK;
> > +
> > + desc->qw1 = qw1;
> > + /*
> > + * Update QW1 before QW0 since QW0 has the valid bit and the
> > + * descriptor might be picked up by the hardware DMA engine
> > + * immediately if it finds a valid descriptor.
> > + */
> > + wmb();
> > + desc->qw0 = qw0;
> > + /*
> > + * This is not smp_wmb() on purpose since we are also publishing the
> > + * descriptor updates to a dma device
> > + */
> > + wmb();
> > +}
> > +
> > +static void mic_dma_fence_intr_desc(struct mic_dma_chan *ch, int flags)
> > +{
> > + /*
> > + * Zero-length DMA memcpy needs valid source and destination addresses
> > + */
> > + mic_dma_memcpy_desc(&ch->desc_ring[ch->head],
> > + ch->desc_ring_da, ch->desc_ring_da, 0, flags);
> > + mic_dma_inc_head(ch);
> > +}
> > +
> > +static int mic_dma_prog_memcpy_desc(struct mic_dma_chan *ch,
> dma_addr_t src,
> > + dma_addr_t dst, size_t len, int flags)
> > +{
> > + struct device *dev = mic_dma_ch_to_device(ch);
> > + size_t current_transfer_len;
> > + size_t max_xfer_size = to_mic_dma_dev(ch)->max_xfer_size;
> > + int num_desc = len / max_xfer_size;
> > + int ret;
> > +
> > + if (len % max_xfer_size)
> > + num_desc++;
> > + /*
> > + * A single additional descriptor is programmed for fence/interrupt
> > + * during submit(..)
> > + */
> > + if (flags)
> > + num_desc++;
> > +
> > + if (!num_desc) {
> > + dev_err(dev, "%s nothing to do: rc %d\n", __func__, -EINVAL);
> > + return -EINVAL;
> > + }
> > +
> > + ret = mic_dma_avail_desc_ring_space(ch, num_desc);
> > + if (ret <= 0) {
> > + dev_err(dev, "%s desc ring full ret %d\n", __func__, ret);
> > + return ret;
> > + }
> > +
> > + while (len > 0) {
> > + current_transfer_len = min(len, max_xfer_size);
> > + /*
> > + * Set flags to 0 here, we don't want memcpy descriptors to
> > + * generate interrupts, a separate descriptor will be programmed
> > + * for fence/interrupt during submit, after a callback is
> > + * guaranteed to have been assigned
> > + */
> > + mic_dma_memcpy_desc(&ch->desc_ring[ch->head],
> > + src, dst, current_transfer_len, 0);
> > + mic_dma_inc_head(ch);
> > + len -= current_transfer_len;
> > + dst = dst + current_transfer_len;
> > + src = src + current_transfer_len;
> > + }
> > + return 0;
> > +}
> > +
> > +static int mic_dma_do_dma(struct mic_dma_chan *ch, int flags, dma_addr_t
> src,
> > + dma_addr_t dst, size_t len)
> > +{
> > + return mic_dma_prog_memcpy_desc(ch, src, dst, len, flags);
> > +}
> > +
> > +static inline void mic_dma_issue_pending(struct dma_chan *ch)
> > +{
> > + struct mic_dma_chan *mic_ch = to_mic_dma_chan(ch);
> > + unsigned long flags;
> > + u32 ctrl_reg;
> > +
> > + spin_lock_irqsave(&mic_ch->issue_lock, flags);
> > + /*
> > + * The notify_hw is introduced because occasionally we were seeing an
> > + * issue where the HW tail seemed stuck, i.e. the DMA engine would not
> > + * pick up new descriptors available in the ring. We found that
> > + * serializing operations between SW and HW made this issue
> > + * disappear. We believe this issue arises because of a race between SW
> > + * and HW. SW adds new descriptors to the ring and clears
> > + * DESC_INVLD_STATUS to ask HW to pick them up. However HW has
> > + * prefetched descriptors and writes DESC_INVLD_STATUS to let SW know
> it
> > + * has fetched an invalid descriptor. It appears that in this way HW can
> > + * overwrite the clearing of DESC_INVLD_STATUS by SW (though we never
> > + * saw DESC_INVLD_STATUS set to 1 when the DMA engine had stopped)
> and
> > + * therefore HW never picks up these descriptors.
> > + *
> > + * Therefore it is necessary for SW to clear DESC_INVLD_STATUS only
> > + * after HW has set it, and the notify_hw flag accomplishes this
> > + * between issue_pending(..) and the invld_desc interrupt handler.
> > + */
> > + if (mic_ch->notify_hw) {
> > + ctrl_reg = mic_dma_ch_reg_read(mic_ch, MIC_DMA_CTRL_STATUS);
> > + if (ctrl_reg & MIC_DMA_CTRL_DESC_INVLD_STATUS) {
> > + mic_ch->notify_hw = 0;
> > + /* Clear DESC_INVLD_STATUS flag */
> > + mic_dma_ch_reg_write(mic_ch, MIC_DMA_CTRL_STATUS,
> > + ctrl_reg);
> > + } else {
> > + dev_err(mic_dma_ch_to_device(mic_ch),
> > + "%s: DESC_INVLD_STATUS not set\n", __func__);
> > + }
> > + }
> > + spin_unlock_irqrestore(&mic_ch->issue_lock, flags);
> > +}
> > +
> > +static inline void mic_dma_update_pending(struct mic_dma_chan *ch)
> > +{
> > + if (mic_dma_ring_count(ch->head, ch->last_tail)
> > + > MIC_DMA_PENDING_LEVEL)
>
> One line?
>
> > + mic_dma_issue_pending(&ch->chan);
> > +}
> > +
> > +static dma_cookie_t mic_dma_tx_submit_unlock(struct
> dma_async_tx_descriptor *tx)
> > +{
> > + struct mic_dma_chan *mic_ch = to_mic_dma_chan(tx->chan);
> > + dma_cookie_t cookie;
> > +
> > + dma_cookie_assign(tx);
> > + cookie = tx->cookie;
> > + /*
> > + * smp_wmb pairs with smb_rmb in mic_dma_cleanup to ensure
> > + * that tx->cookie is visible before updating ch->head
> > + */
> > + smp_wmb();
> > +
> > + /*
> > + * The final fence/interrupt desc is now programmed in submit after the
> > + * cookie has been assigned
> > + */
> > + if (tx->flags) {
> > + mic_dma_fence_intr_desc(mic_ch, tx->flags);
> > + tx->flags = 0;
> > + }
> > +
> > + spin_unlock(&mic_ch->prep_lock);
> > + mic_dma_update_pending(mic_ch);
> > + return cookie;
> > +}
> > +
> > +static inline struct dma_async_tx_descriptor *
> > +allocate_tx(struct mic_dma_chan *ch, unsigned long flags)
> > +{
> > + /* index of the final desc which is or will be programmed */
> > + u32 idx = flags ? ch->head : mic_dma_ring_dec(ch->head);
> > + struct dma_async_tx_descriptor *tx = &ch->tx_array[idx];
> > +
> > + dma_async_tx_descriptor_init(tx, &ch->chan);
> > + tx->tx_submit = mic_dma_tx_submit_unlock;
> > + tx->flags = flags;
> > + return tx;
> > +}
> > +
> > +static struct dma_async_tx_descriptor *
> > +mic_dma_prep_memcpy_lock(struct dma_chan *ch, dma_addr_t dma_dest,
> > + dma_addr_t dma_src, size_t len, unsigned long flags)
> > +{
> > + struct mic_dma_chan *mic_ch = to_mic_dma_chan(ch);
> > + struct device *dev = mic_dma_ch_to_device(mic_ch);
> > + int result;
> > +
> > + /*
> > + * return holding prep_lock which will be released in submit
> > + */
> > + spin_lock(&mic_ch->prep_lock);
> > + result = mic_dma_do_dma(mic_ch, flags, dma_src, dma_dest, len);
>
> > + if (result >= 0)
> > + return allocate_tx(mic_ch, flags);
>
> Hmm… Usual pattern is
> if (err)
> do error path();
>
> > + dev_err(dev, "Error enqueueing dma, error=%d\n", result);
> > + spin_unlock(&mic_ch->prep_lock);
> > + return NULL;
> > +}
> > +
> > +static struct dma_async_tx_descriptor *
> > +mic_dma_prep_interrupt_lock(struct dma_chan *ch, unsigned long flags)
> > +{
> > + struct mic_dma_chan *mic_ch = to_mic_dma_chan(ch);
> > + /*
> > + * Program 0 length DMA. Interrupt desc to be programmed in submit.
> > + * All DMA transfers need a valid source and destination.
> > + */
> > + return mic_dma_prep_memcpy_lock(ch, mic_ch->desc_ring_da,
> > + mic_ch->desc_ring_da, 0, flags);
> > +}
> > +
> > +static irqreturn_t mic_dma_thread_fn(int irq, void *data)
> > +{
> > + struct mic_dma_device *mic_dma_dev = ((struct mic_dma_device
> *)data);
> > +
> > + mic_dma_cleanup(&mic_dma_dev->mic_chan);
> > + return IRQ_HANDLED;
> > +}
> > +
> > +static void mic_dma_invld_desc_interrupt(struct mic_dma_chan *ch)
> > +{
> > + u32 ctrl_reg;
> > +
> > + spin_lock(&ch->issue_lock);
> > + if (!ch->notify_hw) {
> > + ctrl_reg = mic_dma_ch_reg_read(ch, MIC_DMA_CTRL_STATUS);
> > + if (ctrl_reg & MIC_DMA_CTRL_DESC_INVLD_STATUS) {
>
> Isn't too long?
> MIC_DMA_CTRL_DESC_INVLD_STATUS -> MIC_DMA_CTRL_DESC_INVAL ?
>
> > + /*
> > + * Check the descriptor ring for valid descriptors. If
> > + * valid descriptors are available clear the
> > + * DESC_INVLD_STATUS bit to signal to the hardware to
> > + * pick them up. If no valid descriptors are available,
> > + * when issue_pending is called, it will clear the
> > + * INVLD_STATUS bit to signal to the hardware to pick up
> > + * the posted descriptors.
> > + */
> > + if (ch->desc_ring[mic_dma_ring_dec(ch->head)].qw0 &
> > + MIC_DMA_DESC_VALID) {
> > + mic_dma_ch_reg_write(ch, MIC_DMA_CTRL_STATUS,
> > + ctrl_reg);
> > + } else {
> > + ch->notify_hw = 1;
> > + }
> > + } else {
> > + dev_err(mic_dma_ch_to_device(ch),
> > + "%s: DESC_INVLD_STATUS not set\n", __func__);
> > + }
> > + }
> > + spin_unlock(&ch->issue_lock);
> > +}
> > +
> > +static void mic_dma_abort_interrupt(struct mic_dma_chan *ch, u32 intr_reg)
> > +{
> > + u32 reg;
> > + u32 ring_pos;
> > +
> > + spin_lock(&ch->issue_lock);
> > + reg = mic_dma_ch_reg_read(ch, MIC_DMA_LAST_DESC_ADDR_LOW);
> > + ring_pos = desc_ring_da_to_index(ch, reg);
> > +
> > + if (ch->desc_ring[ring_pos].qw0 & MIC_DMA_DESC_VALID) {
> > + /*
> > + * Move back the HW next pointer so it points to the tail of
> > + * the ring descriptor.
> > + */
> > + mic_dma_ch_reg_write(ch, MIC_DMA_NEXT_DESC_ADDR_LOW, reg);
> > + } else {
> > + /* Last descriptor is not valid, find a valid one or head */
> > + u32 tail = ch->last_tail;
> > + u32 new_next;
> > +
> > + while (tail != ch->head) {
> > + tail = mic_dma_ring_inc(tail);
> > + if (ch->desc_ring[ring_pos].qw0 & MIC_DMA_DESC_VALID)
> > + break;
> > + }
> > + new_next = desc_ring_index_to_da(ch, tail);
> > + mic_dma_ch_reg_write(ch, MIC_DMA_NEXT_DESC_ADDR_LOW,
> new_next);
> > +
> > + dev_err(mic_dma_ch_to_device(ch),
> > + "Abort at %d with invalid descriptor, new descr %d, head = %d, tail
> %d\n",
> > + ring_pos, tail, ch->head, ch->last_tail);
> > + }
> > +
> > + /*
> > + * If abort was caused by hw error then restart DMA engine.
> > + * If abort was requested by driver then leave it stopped.
> > + */
> > + if (intr_reg & MIC_DMA_ERROR_INTR_STATUS) {
> > + if (ch->abort_tail != desc_ring_da_to_index(ch, reg)) {
> > + ch->abort_tail = desc_ring_da_to_index(ch, reg);
> > + ch->abort_counter = 0;
> > + } else {
> > + ch->abort_counter++;
> > + }
> > +
> > + if (ch->abort_counter < MIC_DMA_ABORT_LIMIT) {
> > + dev_err(mic_dma_ch_to_device(ch),
> > + "Abort/Error at %d (retry %d), reenabling DMA engine.\n",
> > + ch->abort_tail, ch->abort_counter);
> > + mic_dma_enable_chan(ch);
> > + } else {
> > + /*
> > + * We have tried same descriptor several times and it is
> > + * still generating abort.
> > + */
> > + dev_err(mic_dma_ch_to_device(ch),
> > + "Abort Error at %d (retry %d), give up.\n",
> > + ch->abort_tail, ch->abort_counter);
> > + }
> > + }
> > + spin_unlock(&ch->issue_lock);
> > +}
> > +
> > +static u32 mic_dma_ack_interrupt(struct mic_dma_chan *ch)
> > +{
> > + u32 intr_reg = mic_dma_ch_reg_read(ch,
> MIC_DMA_INTR_CTRL_STATUS);
> > +
> > + mic_dma_ch_reg_write(ch, MIC_DMA_INTR_CTRL_STATUS, intr_reg);
> > + return intr_reg;
> > +}
> > +
> > +static irqreturn_t mic_dma_intr_handler(int irq, void *data)
> > +{
> > + struct mic_dma_device *mic_dma_dev = ((struct mic_dma_device
> *)data);
> > + bool wake_thread = false, error = false;
> > + struct mic_dma_chan *ch = &mic_dma_dev->mic_chan;
> > + struct device *dev = mic_dma_ch_to_device(ch);
> > + u32 reg;
> > +
> > + reg = mic_dma_ack_interrupt(&mic_dma_dev->mic_chan);
> > + wake_thread = !!(reg & MIC_DMA_DESC_DONE_INTR_STATUS);
> > + error = !!(reg & MIC_DMA_ERROR_STATUS);
> > + if (error)
> > + dev_err(dev, "%s error status 0x%x\n", __func__, reg);
> > +
> > + if (reg & MIC_DMA_INVLD_DESC_INTR_STATUS)
> > + mic_dma_invld_desc_interrupt(&mic_dma_dev->mic_chan);
> > +
> > + if (reg & MIC_DMA_ABORT_DONE_INTR_STATUS)
> > + mic_dma_abort_interrupt(&mic_dma_dev->mic_chan, reg);
> > +
> > + if (wake_thread)
> > + return IRQ_WAKE_THREAD;
> > +
> > + if (error || reg & MIC_DMA_INVLD_DESC_INTR_STATUS ||
> > + reg & MIC_DMA_ABORT_DONE_INTR_STATUS)
> > + return IRQ_HANDLED;
> > +
> > + return IRQ_NONE;
> > +}
> > +
> > +static int mic_dma_setup_irq(struct mic_dma_device *mic_dma_dev)
> > +{
> > + struct pci_dev *pdev = mic_dma_dev->pdev;
> > + struct device *dev = &pdev->dev;
> > + int rc = pci_enable_msi(pdev);
> > +
> > + if (rc)
> > + pci_intx(pdev, 1);
> > +
> > + return devm_request_threaded_irq(dev, pdev->irq,
> mic_dma_intr_handler,
> > + mic_dma_thread_fn, IRQF_SHARED,
> > + "mic-x200-dma-intr", mic_dma_dev);
> > +}
> > +
> > +static inline void mic_dma_free_irq(struct mic_dma_device *mic_dma_dev)
> > +{
> > + struct pci_dev *pdev = mic_dma_dev->pdev;
> > + struct device *dev = &pdev->dev;
> > +
> > + devm_free_irq(dev, pdev->irq, mic_dma_dev);
>
> > + if (pci_dev_msi_enabled(pdev))
> > + pci_disable_msi(pdev);
>
> pcim_enable_device() will take care of this one.
>
> > +}
> > +
> > +static void mic_dma_hw_init(struct mic_dma_device *mic_dma_dev)
> > +{
> > + struct mic_dma_chan *ch = &mic_dma_dev->mic_chan;
> > + u32 intr_reg;
> > +
> > + dev_dbg(mic_dma_dev->dma_dev.dev, "Ctrl reg 0x%0x, Intr reg
> 0x%0x\n",
> > + mic_dma_reg_read(mic_dma_dev, MIC_DMA_CTRL_STATUS),
> > + mic_dma_reg_read(mic_dma_dev, MIC_DMA_INTR_CTRL_STATUS));
> > +
> > + intr_reg = mic_dma_ch_reg_read(ch, MIC_DMA_INTR_CTRL_STATUS);
> > + if (intr_reg & MIC_DMA_ALL_INTR_EN) {
> > + /*
> > + * Interrupts are enabled - that means card has been reset
> > + * without resetting DMA HW.
> > + * Disable interrupts and issue abort to stop DMA HW.
> > + */
> > + intr_reg &= ~(MIC_DMA_ALL_INTR_EN);
>
> Redundant parens.
>
> > + mic_dma_ch_reg_write(ch, MIC_DMA_INTR_CTRL_STATUS, intr_reg);
> > + mic_dma_disable_chan(ch);
> > + }
> > +
> > + mic_dma_reg_write(mic_dma_dev, MIC_DMA_CTRL_STATUS,
> > + MIC_DMA_CTRL_STATUS_INIT);
> > +
> > + mic_dma_reg_write(mic_dma_dev, MIC_DMA_CHAN_BANDWIDTH,
> > + MIC_DMA_MAX_DST_MEM_WRITE);
> > +
> > + mic_dma_reg_write(mic_dma_dev, MIC_DMA_STA_RAM_THRESH,
> > + MIC_DMA_STA_RAM_THRESH_INIT);
> > +
> > + mic_dma_reg_write(mic_dma_dev, MIC_DMA_STA0_HDR_RAM,
> > + MIC_DMA_STA_HDR_THRESH_INIT);
> > + mic_dma_reg_write(mic_dma_dev, MIC_DMA_STA1_HDR_RAM,
> > + MIC_DMA_STA_HDR_THRESH_INIT);
> > +
> > + mic_dma_reg_write(mic_dma_dev, MIC_DMA_STA0_PLD_RAM,
> > + MIC_DMA_STA_PLD_THRESH_INIT);
> > + mic_dma_reg_write(mic_dma_dev, MIC_DMA_STA1_PLD_RAM,
> > + MIC_DMA_STA_PLD_THRESH_INIT);
> > +}
> > +
> > +static int mic_dma_init(struct mic_dma_device *mic_dma_dev)
> > +{
> > + struct mic_dma_chan *ch;
>
> > + int rc = 0;
>
> Useless assignment.
>
> > +
> > + mic_dma_hw_init(mic_dma_dev);
> > +
> > + rc = mic_dma_setup_irq(mic_dma_dev);
> > + if (rc) {
> > + dev_err(mic_dma_dev->dma_dev.dev,
> > + "%s %d func error line %d\n", __func__, __LINE__, rc);
> > + goto error;
> > + }
> > + ch = &mic_dma_dev->mic_chan;
> > + spin_lock_init(&ch->cleanup_lock);
> > + spin_lock_init(&ch->prep_lock);
> > + spin_lock_init(&ch->issue_lock);
>
> > +error:
>
> Useless label.
>
> > + return rc;
> > +}
> > +
> > +static void mic_dma_uninit(struct mic_dma_device *mic_dma_dev)
> > +{
> > + mic_dma_free_irq(mic_dma_dev);
> > +}
> > +
> > +static int mic_register_dma_device(struct mic_dma_device *mic_dma_dev)
> > +{
> > + struct dma_device *dma_dev = &mic_dma_dev->dma_dev;
> > + struct mic_dma_chan *ch;
> > +
> > + dma_cap_zero(dma_dev->cap_mask);
> > +
> > + dma_cap_set(DMA_PRIVATE, dma_dev->cap_mask);
> > + dma_cap_set(DMA_MEMCPY, dma_dev->cap_mask);
> > +
> > + dma_dev->device_alloc_chan_resources =
> mic_dma_alloc_chan_resources;
> > + dma_dev->device_free_chan_resources =
> mic_dma_free_chan_resources;
> > + dma_dev->device_tx_status = mic_dma_tx_status;
> > + dma_dev->device_prep_dma_memcpy = mic_dma_prep_memcpy_lock;
> > + dma_dev->device_prep_dma_interrupt = mic_dma_prep_interrupt_lock;
> > + dma_dev->device_issue_pending = mic_dma_issue_pending;
> > + INIT_LIST_HEAD(&dma_dev->channels);
> > +
> > + /* Associate dma_dev with dma_chan */
> > + ch = &mic_dma_dev->mic_chan;
> > + ch->chan.device = dma_dev;
> > + dma_cookie_init(&ch->chan);
> > + list_add_tail(&ch->chan.device_node, &dma_dev->channels);
> > + return dma_async_device_register(dma_dev);
> > +}
> > +
> > +static int mic_dma_probe(struct mic_dma_device *mic_dma_dev)
> > +{
> > + struct dma_device *dma_dev;
> > + int rc = -EINVAL;
> > +
> > + dma_dev = &mic_dma_dev->dma_dev;
> > + dma_dev->dev = &mic_dma_dev->pdev->dev;
> > +
> > + /* MIC X200 has one DMA channel per function */
> > + dma_dev->chancnt = 1;
> > +
> > + mic_dma_dev->max_xfer_size = MIC_DMA_DESC_SIZE_MASK;
> > +
> > + rc = mic_dma_init(mic_dma_dev);
> > + if (rc) {
> > + dev_err(&mic_dma_dev->pdev->dev,
> > + "%s %d rc %d\n", __func__, __LINE__, rc);
> > + goto init_error;
> > + }
> > +
> > + rc = mic_register_dma_device(mic_dma_dev);
> > + if (rc) {
> > + dev_err(&mic_dma_dev->pdev->dev,
> > + "%s %d rc %d\n", __func__, __LINE__, rc);
> > + goto reg_error;
> > + }
> > + return rc;
> > +reg_error:
> > + mic_dma_uninit(mic_dma_dev);
>
> > +init_error:
>
> Ditto.
>
> > + return rc;
> > +}
> > +
> > +static void mic_dma_remove(struct mic_dma_device *mic_dma_dev)
> > +{
> > + dma_async_device_unregister(&mic_dma_dev->dma_dev);
> > + mic_dma_uninit(mic_dma_dev);
> > +}
> > +
> > +static struct mic_dma_device *
> > +mic_x200_alloc_dma(struct pci_dev *pdev, void __iomem *iobase)
> > +{
> > + struct mic_dma_device *d = kzalloc(sizeof(*d), GFP_KERNEL);
>
> devm_
>
> > +
> > + if (!d)
> > + return NULL;
> > + d->pdev = pdev;
> > + d->reg_base = iobase;
> > + return d;
> > +}
> > +
> > +static int
> > +mic_x200_dma_probe(struct pci_dev *pdev, const struct pci_device_id
> *pdev_id)
> > +{
> > + int rc;
> > + struct mic_dma_device *dma_dev;
> > + void __iomem * const *iomap;
> > +
> > + rc = pcim_enable_device(pdev);
> > + if (rc)
> > + goto done;
> > + rc = pcim_iomap_regions(pdev, 0x1, MIC_DMA_DRV_NAME);
> > + if (rc)
> > + goto done;
>
> > + iomap = pcim_iomap_table(pdev);
>
> > + if (!iomap) {
> > + rc = -ENOMEM;
> > + goto done;
> > + }
>
> Redundant check. Previous one fail otherwise this is valid.
>
> > + rc = pci_set_dma_mask(pdev, DMA_BIT_MASK(48));
> > + if (rc)
> > + goto done;
> > + rc = pci_set_consistent_dma_mask(pdev, DMA_BIT_MASK(48));
> > + if (rc)
> > + goto done;
> > + dma_dev = mic_x200_alloc_dma(pdev, iomap[0]);
> > + if (!dma_dev) {
> > + rc = -ENOMEM;
> > + goto done;
> > + }
> > + pci_set_master(pdev);
> > + pci_set_drvdata(pdev, dma_dev);
> > + rc = mic_dma_probe(dma_dev);
> > + if (rc)
> > + goto probe_err;
> > + return 0;
>
> > +probe_err:
> > + kfree(dma_dev);
>
> devm_ takes care of.
>
> > +done:
> > + dev_err(&pdev->dev, "probe error rc %d\n", rc);
>
> Useless. You may learn "initcall_debug" parameter.
>
> And thus label is useless.
>
> > + return rc;
> > +}
> > +
> > +static void mic_x200_dma_remove(struct pci_dev *pdev)
> > +{
> > + struct mic_dma_device *dma_dev = pci_get_drvdata(pdev);
> > +
> > + mic_dma_remove(dma_dev);
>
> > + kfree(dma_dev);
>
> devm_
>
> > +}
> > +
> > +static struct pci_device_id mic_x200_dma_pci_id_table[] = {
> > + {PCI_DEVICE(PCI_VENDOR_ID_INTEL, 0x2264)},
> > + {}
> > +};
> > +MODULE_DEVICE_TABLE(pci, mic_x200_dma_pci_id_table);
> > +
> > +static struct pci_driver mic_x200_dma_driver = {
> > + .name = MIC_DMA_DRV_NAME,
> > + .id_table = mic_x200_dma_pci_id_table,
> > + .probe = mic_x200_dma_probe,
> > + .remove = mic_x200_dma_remove
>
> > +};
> > +
> > +static int __init mic_x200_dma_init(void)
> > +{
> > + int rc = pci_register_driver(&mic_x200_dma_driver);
> > +
> > + if (rc)
> > + pr_err("%s %d rc %x\n", __func__, __LINE__, rc);
> > + return rc;
> > +}
> > +
> > +static void __exit mic_x200_dma_exit(void)
> > +{
> > + pci_unregister_driver(&mic_x200_dma_driver);
> > +}
> > +
> > +module_init(mic_x200_dma_init);
> > +module_exit(mic_x200_dma_exit);
>
> module_pci_driver();
>
> > +
> > +MODULE_AUTHOR("Intel Corporation");
> > +MODULE_DESCRIPTION("Intel(R) MIC X200 DMA Driver");
> > +MODULE_LICENSE("GPL v2");
> > --
> > 2.1.4
> >
>
>
>
> --
> With Best Regards,
> Andy Shevchenko
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  Last update: 2016-02-09 13:41    [W:0.137 / U:13.884 seconds]
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