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SubjectRe: [PATCH v5 3/4] remoteproc/MIPS: Add a remoteproc driver for MIPS
From
Date
Hi Bjorn,

Please could you review this driver?

Thanks,

Matt


On 11/01/17 15:34, Matt Redfearn wrote:
> This driver allows a MIPS processor offlined from Linux to be used as a
> remote processor. Firmware may be loaded via the sysfs interface and
> changed at runtime, allowing the processor to handle real-time tasks or
> perform coprocessing while remaining processors are available to Linux.
>
> Coprocessor firmware must abide by the remoteproc standard, i.e.
> implement the resource table containing memory layouts and virtio device
> descriptions, and additionally abide by the MIPS UHI coprocessor boot
> protocol in the startup code.
>
> Signed-off-by: Lisa Parratt <lisa.parratt@imgtec.com>
> Signed-off-by: Matt Redfearn <matt.redfearn@imgtec.com>
>
> ---
>
> Changes in v5:
> Depend on !64bit since this driver only works with 32bit kernels
> Set mproc->tsk state to TASK_DEAD before freeing it to avoid warning
> Flush icache of each carveout so that icache sees latest data written
>
> Changes in v4:
> Have a single mips-rproc device to be parent to each CPU's rproc device.
> Support per-device coherence introduced in v4.9
> Add a sysfs interface to control the mask of cpus available to rproc
>
> Changes in v3:
> Update MIPS remoteproc driver to use CPU hotplug state machine
> Remove sysfs interface from MIPS rproc driver, now provided by the core.
> Drop patches that Ralf has already merged to mips-next
>
> Changes in v2: None
>
> Documentation/ABI/testing/sysfs-devices-mips-rproc | 13 +
> drivers/remoteproc/Kconfig | 11 +
> drivers/remoteproc/Makefile | 1 +
> drivers/remoteproc/mips_remoteproc.c | 596 +++++++++++++++++++++
> 4 files changed, 621 insertions(+)
> create mode 100644 Documentation/ABI/testing/sysfs-devices-mips-rproc
> create mode 100644 drivers/remoteproc/mips_remoteproc.c
>
> diff --git a/Documentation/ABI/testing/sysfs-devices-mips-rproc b/Documentation/ABI/testing/sysfs-devices-mips-rproc
> new file mode 100644
> index 000000000000..b06f6671807a
> --- /dev/null
> +++ b/Documentation/ABI/testing/sysfs-devices-mips-rproc
> @@ -0,0 +1,13 @@
> +What: /sys/devices/mips-rproc/cpus
> +Date: October 2016
> +Contact: Matt Redfearn <matt.redfearn@imgtec.com>
> +Description:
> + CPU topology file describing which CPUs may be used by the
> + MIPS remote processor driver when offline from Linux.
> +
> + This can be read to observe the current setting, or written to
> + change the allowed CPUs.
> +
> + The format is compatible with cpulist_parse()
> + [see <linux/cpumask.h>], for example to enable the MIPS remote
> + processor driver on CPUs 1,2 & 3, write "1-3" into this file.
> diff --git a/drivers/remoteproc/Kconfig b/drivers/remoteproc/Kconfig
> index 8f9cf0bc571c..3be2202f639d 100644
> --- a/drivers/remoteproc/Kconfig
> +++ b/drivers/remoteproc/Kconfig
> @@ -68,6 +68,17 @@ config DA8XX_REMOTEPROC
> It's safe to say n here if you're not interested in multimedia
> offloading.
>
> +config MIPS_REMOTEPROC
> + tristate "MIPS remoteproc support"
> + depends on MIPS_CPS && HAS_DMA && !64BIT
> + depends on REMOTEPROC
> + select CMA
> + select MIPS_CPU_STEAL
> + help
> + Say y here to support using offline cores/VPEs as remote processors
> + via the remote processor framework.
> + If unsure say N.
> +
> config QCOM_ADSP_PIL
> tristate "Qualcomm ADSP Peripheral Image Loader"
> depends on OF && ARCH_QCOM
> diff --git a/drivers/remoteproc/Makefile b/drivers/remoteproc/Makefile
> index 0938ea3c41ba..580ee8907da9 100644
> --- a/drivers/remoteproc/Makefile
> +++ b/drivers/remoteproc/Makefile
> @@ -11,6 +11,7 @@ remoteproc-y += remoteproc_elf_loader.o
> obj-$(CONFIG_OMAP_REMOTEPROC) += omap_remoteproc.o
> obj-$(CONFIG_WKUP_M3_RPROC) += wkup_m3_rproc.o
> obj-$(CONFIG_DA8XX_REMOTEPROC) += da8xx_remoteproc.o
> +obj-$(CONFIG_MIPS_REMOTEPROC) += mips_remoteproc.o
> obj-$(CONFIG_QCOM_ADSP_PIL) += qcom_adsp_pil.o
> obj-$(CONFIG_QCOM_MDT_LOADER) += qcom_mdt_loader.o
> obj-$(CONFIG_QCOM_Q6V5_PIL) += qcom_q6v5_pil.o
> diff --git a/drivers/remoteproc/mips_remoteproc.c b/drivers/remoteproc/mips_remoteproc.c
> new file mode 100644
> index 000000000000..9a2a7bbddc0a
> --- /dev/null
> +++ b/drivers/remoteproc/mips_remoteproc.c
> @@ -0,0 +1,596 @@
> +/*
> + * MIPS Remote Processor driver
> + *
> + * Copyright (C) 2016 Imagination Technologies
> + * Lisa Parratt <lisa.parratt@imgtec.com>
> + * Matt Redfearn <matt.redfearn@imgtec.com>
> + *
> + * 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; either version 2 of the License, or (at your
> + * option) any later version.
> + */
> +
> +#include <linux/cpu.h>
> +#include <linux/dma-mapping.h>
> +#include <linux/interrupt.h>
> +#include <linux/io.h>
> +#include <linux/irq.h>
> +#include <linux/module.h>
> +#include <linux/of_irq.h>
> +#include <linux/platform_device.h>
> +#include <linux/remoteproc.h>
> +
> +#include <asm/cacheflush.h>
> +#include <asm/smp-cps.h>
> +#include <asm/tlbflush.h>
> +#include <asm/tlbmisc.h>
> +
> +#include "remoteproc_internal.h"
> +
> +struct mips_rproc {
> + char name[16];
> + struct rproc *rproc;
> + struct task_struct *tsk;
> + unsigned int cpu;
> + int ipi_linux;
> + int ipi_remote;
> +};
> +
> +/* Parent device for MIPS remoteproc */
> +static struct device mips_rproc_dev;
> +
> +/* Array of allocated MIPS remote processor instances */
> +static struct mips_rproc *mips_rprocs[NR_CPUS];
> +
> +/* Bitmap used to identify which CPUs are available to rproc */
> +static cpumask_var_t mips_rproc_cpumask;
> +
> +/* Dynamic CPU hotplug state associated with this driver */
> +static int cpuhp_state;
> +
> +/* Add wired entry to map a device address to physical memory */
> +static void mips_map_page(unsigned long da, unsigned long pa, int c,
> + unsigned long pagesize)
> +{
> + unsigned long pa2 = pa + (pagesize / 2);
> + unsigned long entryhi, entrylo0, entrylo1;
> + unsigned long pagemask = pagesize - 0x2000;
> +
> + pa = (pa >> 6) & (ULONG_MAX << MIPS_ENTRYLO_PFN_SHIFT);
> + pa2 = (pa2 >> 6) & (ULONG_MAX << MIPS_ENTRYLO_PFN_SHIFT);
> + entryhi = da & 0xfffffe000;
> + entrylo0 = (c << ENTRYLO_C_SHIFT) | ENTRYLO_D | ENTRYLO_V | pa;
> + entrylo1 = (c << ENTRYLO_C_SHIFT) | ENTRYLO_D | ENTRYLO_V | pa2;
> +
> + pr_debug("Create wired entry %d, CCA %d\n", read_c0_wired(), c);
> + pr_debug(" EntryHi: 0x%016lx\n", entryhi);
> + pr_debug(" EntryLo0: 0x%016lx\n", entrylo0);
> + pr_debug(" EntryLo1: 0x%016lx\n", entrylo1);
> + pr_debug(" Pagemask: 0x%016lx\n", pagemask);
> + pr_debug("\n");
> +
> + add_wired_entry(entrylo0, entrylo1, entryhi, pagemask);
> +}
> +
> +/* Compute the largest page mask a physical address can be mapped with */
> +static unsigned long mips_rproc_largest_pm(unsigned long pa,
> + unsigned long maxmask)
> +{
> + unsigned long mask;
> + /* Find address bits limiting alignment */
> + unsigned long shift = ffs(pa);
> +
> + /* Obey MIPS restrictions on page sizes */
> + if (pa) {
> + if (shift & 1)
> + shift -= 2;
> + else
> + shift--;
> + }
> + mask = ULONG_MAX << shift;
> + return maxmask & ~mask;
> +}
> +
> +/* Compute the page mask one step larger than a given page mask */
> +static unsigned long mips_rproc_next_pm(unsigned long pm, unsigned long maxmask)
> +{
> +#define PM_SHIFT 13
> + return ((pm << 2) | (0x3 << PM_SHIFT)) & maxmask;
> +}
> +
> +/*
> + * Add mappings to the TLB such that memory allocated by the kernel for a
> + * firmware component appears at the right virtual address
> + */
> +static inline void mips_rproc_map(unsigned long da, unsigned long pa, int c,
> + unsigned long size, unsigned long maxmask)
> +{
> + /* minimum mappable size is 2 * 4k pages */
> + const unsigned long min_map_sz = 0x2000;
> + unsigned long bigmask, nextmask;
> + unsigned long distance, target;
> + unsigned long page2_size; /* Size of the 2 buddy pages */
> +
> + do {
> + /* Compute the current largest page mask */
> + bigmask = mips_rproc_largest_pm(pa, maxmask);
> + /* Compute the next largest pagesize */
> + nextmask = mips_rproc_next_pm(bigmask, maxmask);
> + /*
> + * Compute the distance from our current physical address to
> + * the next page boundary.
> + */
> + distance = (nextmask + min_map_sz) - (pa & nextmask);
> + /*
> + * Decide between searching to get to the next highest page
> + * boundary or finishing.
> + */
> + target = distance < size ? distance : size;
> + while (target) {
> + /* Find the largest supported page size that will fit */
> + for (page2_size = maxmask + min_map_sz;
> + (page2_size > min_map_sz) && (page2_size > target);
> + page2_size /= 4) {
> + }
> + /* Emit it */
> + mips_map_page(da, pa, c, page2_size);
> + /* Move to next step */
> + size -= page2_size;
> + da += page2_size;
> + pa += page2_size;
> + target -= page2_size;
> + }
> + } while (size);
> +}
> +
> +static int mips_rproc_carveouts(struct rproc *rproc, int max_pagemask)
> +{
> + struct rproc_mem_entry *carveout;
> +
> + list_for_each_entry(carveout, &rproc->carveouts, node) {
> + int c = CONF_CM_CACHABLE_COW;
> +
> + dev_dbg(&rproc->dev,
> + "carveout mapping da 0x%x -> %pad length 0x%x, CCA %d",
> + carveout->da, &carveout->dma, carveout->len, c);
> +
> + mips_rproc_map(carveout->da, carveout->dma, c,
> + carveout->len, max_pagemask);
> + flush_icache_range((unsigned long)carveout->va,
> + (unsigned long)carveout->va + carveout->len);
> + }
> + return 0;
> +}
> +
> +static int mips_rproc_vdevs(struct rproc *rproc, int max_pagemask)
> +{
> + struct rproc_vdev *rvdev;
> +
> + list_for_each_entry(rvdev, &rproc->rvdevs, node) {
> + int i, size;
> +
> + for (i = 0; i < ARRAY_SIZE(rvdev->vring); i++) {
> + struct rproc_vring *vring = &rvdev->vring[i];
> + unsigned long pa = vring->dma;
> + int c;
> +
> + if (plat_device_is_coherent(&mips_rproc_dev)) {
> + /*
> + * The DMA API will allocate cacheable buffers
> + * for shared resources, so the firmware should
> + * also access those buffers cached
> + */
> + c = (_page_cachable_default >> _CACHE_SHIFT);
> + } else {
> + /*
> + * Otherwise, shared buffers should be accessed
> + * uncached
> + */
> + c = CONF_CM_UNCACHED;
> + }
> +
> + /* actual size of vring (in bytes) */
> + size = PAGE_ALIGN(vring_size(vring->len, vring->align));
> +
> + dev_dbg(&rproc->dev,
> + "vring mapping da %pad -> %pad length 0x%x, CCA %d",
> + &vring->dma, &vring->dma, size, c);
> +
> + mips_rproc_map(pa, pa, c, size, max_pagemask);
> + }
> + }
> + return 0;
> +}
> +
> +static void mips_rproc_cpu_entry(void)
> +{
> + struct mips_rproc *mproc = mips_rprocs[smp_processor_id()];
> + struct rproc *rproc = mproc->rproc;
> + int ipi_to_remote = ipi_get_hwirq(mproc->ipi_remote, mproc->cpu);
> + int ipi_from_remote = ipi_get_hwirq(mproc->ipi_linux, 0);
> + unsigned long old_pagemask, max_pagemask;
> + void (*fw_entry)(int, int ipi_to_remote, int ipi_from_remote, int);
> +
> + dev_info(&rproc->dev, "%s booting firmware %s\n",
> + rproc->name, rproc->firmware);
> +
> + /* Get the maximum pagemask supported on this CPU */
> + old_pagemask = read_c0_pagemask();
> + write_c0_pagemask(~0);
> + back_to_back_c0_hazard();
> + max_pagemask = read_c0_pagemask();
> + write_c0_pagemask(old_pagemask);
> + back_to_back_c0_hazard();
> +
> + /* Start with no wired entries */
> + write_c0_wired(0);
> +
> + /* Flush all previous TLB entries */
> + local_flush_tlb_all();
> +
> + /* Set ASID 0 */
> + write_c0_entryhi(0);
> +
> + /* Map firmware resources into virtual memory */
> + mips_rproc_carveouts(rproc, max_pagemask);
> + mips_rproc_vdevs(rproc, max_pagemask);
> +
> + dev_dbg(&rproc->dev, "IPI to remote: %d\n", ipi_to_remote);
> + dev_dbg(&rproc->dev, "IPI from remote: %d\n", ipi_from_remote);
> +
> + /* Hand off the CPU to the firmware */
> + dev_dbg(&rproc->dev, "Jumping to firmware at 0x%x\n", rproc->bootaddr);
> +
> + /* Jump into the firmware, obeying the firmware protocol. */
> + fw_entry = (void *)rproc->bootaddr;
> + fw_entry(-3, ipi_to_remote, ipi_from_remote, 0);
> +}
> +
> +static irqreturn_t mips_rproc_ipi_handler(int irq, void *dev_id)
> +{
> + /* Synthetic interrupts shouldn't need acking */
> + return IRQ_WAKE_THREAD;
> +}
> +
> +static irqreturn_t mips_rproc_vq_int(int irq, void *p)
> +{
> + struct rproc *rproc = (struct rproc *)p;
> + void *entry;
> + int id;
> +
> + /* We don't have a mailbox, so iterate over all vqs and kick them. */
> + idr_for_each_entry(&rproc->notifyids, entry, id)
> + rproc_vq_interrupt(rproc, id);
> +
> + return IRQ_HANDLED;
> +}
> +
> +/* Helper function to find the IPI domain */
> +static struct irq_domain *ipi_domain(void)
> +{
> + struct device_node *node = of_irq_find_parent(of_root);
> + struct irq_domain *ipidomain;
> +
> + ipidomain = irq_find_matching_host(node, DOMAIN_BUS_IPI);
> + /*
> + * Some platforms have half DT setup. So if we found irq node but
> + * didn't find an ipidomain, try to search for one that is not in the
> + * DT.
> + */
> + if (node && !ipidomain)
> + ipidomain = irq_find_matching_host(NULL, DOMAIN_BUS_IPI);
> +
> + return ipidomain;
> +}
> +
> +int mips_rproc_op_start(struct rproc *rproc)
> +{
> + struct mips_rproc *mproc = rproc->priv;
> + int err;
> + int cpu = mproc->cpu;
> +
> + /* Create task for the CPU to use before handing off to firmware */
> + mproc->tsk = fork_idle(cpu);
> + if (IS_ERR(mproc->tsk)) {
> + dev_err(&rproc->dev, "fork_idle() failed for CPU%d\n", cpu);
> + return -ENOMEM;
> + }
> +
> + /* We won't be needing the Linux IPIs anymore */
> + if (mips_smp_ipi_free(get_cpu_mask(cpu))) {
> + dev_err(&rproc->dev, "Failed to reserve incoming kick\n");
> + goto exit_free_tsk;
> + }
> +
> + /*
> + * Direct IPIs from the remote processor to CPU0 since that can't be
> + * offlined while the remote CPU is running.
> + */
> + mproc->ipi_linux = irq_reserve_ipi(ipi_domain(), get_cpu_mask(0));
> + if (!mproc->ipi_linux) {
> + dev_err(&rproc->dev, "Failed to reserve incoming kick\n");
> + goto exit_restore_ipi;
> + }
> +
> + mproc->ipi_remote = irq_reserve_ipi(ipi_domain(), get_cpu_mask(cpu));
> + if (!mproc->ipi_remote) {
> + dev_err(&rproc->dev, "Failed to reserve outgoing kick\n");
> + goto exit_destroy_ipi_linux;
> + }
> +
> + /* register incoming ipi */
> + err = request_threaded_irq(mproc->ipi_linux, mips_rproc_ipi_handler,
> + mips_rproc_vq_int, 0,
> + "mips-rproc IPI in", rproc);
> + if (err) {
> + dev_err(&rproc->dev, "Failed to register incoming kick: %d\n",
> + err);
> + goto exit_destroy_ipi_remote;
> + }
> +
> + if (mips_cps_steal_cpu_and_execute(cpu, &mips_rproc_cpu_entry,
> + mproc->tsk)) {
> + dev_err(&rproc->dev, "Failed to steal CPU%d for remote\n", cpu);
> + goto exit_free_irq;
> + }
> +
> + return 0;
> +
> +exit_free_irq:
> + free_irq(mproc->ipi_linux, rproc);
> +exit_destroy_ipi_remote:
> + irq_destroy_ipi(mproc->ipi_remote, get_cpu_mask(cpu));
> +exit_destroy_ipi_linux:
> + irq_destroy_ipi(mproc->ipi_linux, get_cpu_mask(0));
> +exit_restore_ipi:
> + /* Set up the Linux IPIs again */
> + mips_smp_ipi_allocate(get_cpu_mask(cpu));
> +exit_free_tsk:
> + free_task(mproc->tsk);
> +
> + return -EINVAL;
> +}
> +
> +int mips_rproc_op_stop(struct rproc *rproc)
> +{
> + struct mips_rproc *mproc = rproc->priv;
> +
> + free_irq(mproc->ipi_linux, rproc);
> +
> + irq_destroy_ipi(mproc->ipi_linux, get_cpu_mask(0));
> + irq_destroy_ipi(mproc->ipi_remote, get_cpu_mask(mproc->cpu));
> +
> + /* Set up the Linux IPIs again */
> + mips_smp_ipi_allocate(get_cpu_mask(mproc->cpu));
> +
> + set_task_state(mproc->tsk, TASK_DEAD);
> + free_task(mproc->tsk);
> +
> + return mips_cps_halt_and_return_cpu(mproc->cpu);
> +}
> +
> +void mips_rproc_op_kick(struct rproc *rproc, int vqid)
> +{
> + struct mips_rproc *mproc = rproc->priv;
> +
> + if (rproc->state == RPROC_RUNNING)
> + ipi_send_single(mproc->ipi_remote, mproc->cpu);
> +}
> +
> +static const struct rproc_ops mips_rproc_proc_ops = {
> + .start = mips_rproc_op_start,
> + .stop = mips_rproc_op_stop,
> + .kick = mips_rproc_op_kick,
> +};
> +
> +/* Create an rproc instance in response to CPU down */
> +static int mips_rproc_device_register(unsigned int cpu)
> +{
> + char *template = "mips-cpu%u";
> + struct rproc *rproc;
> + struct mips_rproc *mproc;
> + int err;
> +
> + if (!cpumask_test_cpu(cpu, mips_rproc_cpumask))
> + /* The CPU is not in the mask, so don't register rproc on it */
> + return 0;
> +
> + pr_debug("Allocating MIPS rproc for cpu%d\n", cpu);
> +
> + if (mips_rprocs[cpu]) {
> + dev_err(&mips_rproc_dev, "CPU%d in use\n", cpu);
> + return 0;
> + }
> +
> + mproc = kzalloc(sizeof(struct mips_rproc), GFP_KERNEL);
> + if (!mproc) {
> + err = -ENOMEM;
> + goto exit;
> + }
> +
> + snprintf(mproc->name, sizeof(mproc->name), template, cpu);
> + mproc->cpu = cpu;
> +
> + rproc = rproc_alloc(&mips_rproc_dev, mproc->name,
> + &mips_rproc_proc_ops, NULL,
> + sizeof(struct mips_rproc *));
> + if (!rproc) {
> + dev_err(&mips_rproc_dev, "Error allocating rproc\n");
> + err = -ENOMEM;
> + goto exit_free_mproc;
> + }
> +
> + mproc->rproc = rproc;
> + rproc->priv = (void *)mproc;
> +
> + err = rproc_add(rproc);
> + if (err) {
> + dev_err(&mips_rproc_dev, "Failed to add rproc: %d\n", err);
> + goto exit_free_rproc;
> + }
> +
> + mips_rprocs[cpu] = mproc;
> + return 0;
> +
> +exit_free_rproc:
> + rproc_free(rproc);
> +exit_free_mproc:
> + kfree(mproc);
> +exit:
> + return err;
> +}
> +
> +/* Destroy rproc instance in response to CPU up */
> +static int mips_rproc_device_unregister(unsigned int cpu)
> +{
> + struct mips_rproc *mproc = mips_rprocs[cpu];
> +
> + if (!mproc)
> + /* No rproc instance has been created for this CPU */
> + return 0;
> +
> + pr_debug("Deallocating MIPS rproc for cpu%d\n", cpu);
> +
> + rproc_del(mproc->rproc);
> + rproc_put(mproc->rproc);
> + kfree(mproc);
> +
> + mips_rprocs[cpu] = NULL;
> + return 0;
> +}
> +
> +/* Show MIPS CPUs available to rproc */
> +static ssize_t cpus_show(struct device *dev, struct device_attribute *attr,
> + char *buf)
> +{
> + return cpumap_print_to_pagebuf(true, buf, mips_rproc_cpumask);
> +}
> +
> +/* Allow MIPS CPUs to be made available to rproc */
> +static ssize_t cpus_store(struct device *dev,
> + struct device_attribute *attr,
> + const char *buf, size_t count)
> +{
> + static cpumask_var_t new_mask;
> + int err, cpu;
> +
> + err = cpulist_parse(buf, new_mask);
> + if (err)
> + return err;
> +
> + /* Prevent CPU hotplug on/offlining CPUs while we do this */
> + get_online_cpus();
> +
> + for_each_possible_cpu(cpu) {
> + if (cpumask_test_cpu(cpu, mips_rproc_cpumask) &&
> + !cpumask_test_cpu(cpu, new_mask)) {
> + /* CPU no longer allowed. Release any instance on it */
> + cpumask_clear_cpu(cpu, mips_rproc_cpumask);
> + mips_rproc_device_unregister(cpu);
> +
> + } else if (!cpumask_test_cpu(cpu, mips_rproc_cpumask) &&
> + cpumask_test_cpu(cpu, new_mask)) {
> + /* If the CPU isn't online, start an instance */
> + cpumask_set_cpu(cpu, mips_rproc_cpumask);
> + if (!cpu_online(cpu))
> + mips_rproc_device_register(cpu);
> + }
> + }
> + put_online_cpus();
> + return count;
> +}
> +static DEVICE_ATTR_RW(cpus);
> +
> +static struct attribute *mips_rproc_attrs[] = {
> + &dev_attr_cpus.attr,
> + NULL
> +};
> +
> +static const struct attribute_group mips_rproc_devgroup = {
> + .attrs = mips_rproc_attrs
> +};
> +
> +static const struct attribute_group *mips_rproc_devgroups[] = {
> + &mips_rproc_devgroup,
> + NULL
> +};
> +static struct device_type mips_rproc_type = {
> + .groups = mips_rproc_devgroups,
> +};
> +
> +static struct platform_driver mips_rproc_driver = {
> + .driver = {
> + .name = "mips-rproc",
> + },
> +};
> +
> +static int __init mips_rproc_init(void)
> +{
> + int err;
> +
> + if ((!cpu_has_mipsmt) && (!cpu_has_vp)) {
> + pr_debug("MIPS rproc not supported on this cpu\n");
> + return -EIO;
> + }
> +
> + mips_rproc_dev.driver = &mips_rproc_driver.driver;
> + mips_rproc_dev.type = &mips_rproc_type;
> + dev_set_name(&mips_rproc_dev, "mips-rproc");
> +
> + /* Set device to have coherent DMA ops */
> + arch_setup_dma_ops(&mips_rproc_dev, 0, 0, NULL, 1);
> +
> + err = device_register(&mips_rproc_dev);
> + if (err) {
> + dev_err(&mips_rproc_dev, "Error adding MIPS rproc: %d\n", err);
> + return err;
> + }
> +
> + /*
> + * Register with the cpu hotplug state machine.
> + * This driver requires opposite sense to "normal" drivers, since the
> + * driver is activated for offline CPUs via the teardown callback and
> + * deactivated via the online callback.
> + */
> + err = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "MIPS:REMOTEPROC",
> + mips_rproc_device_unregister,
> + mips_rproc_device_register);
> + if (err < 0) {
> + device_unregister(&mips_rproc_dev);
> + return err;
> + }
> +
> + cpuhp_state = err;
> +
> + return 0;
> +}
> +
> +static void __exit mips_rproc_exit(void)
> +{
> + int cpu;
> +
> + if (cpuhp_state) {
> + /*
> + * Unregister with the cpu hotplug state machine, but don't call
> + * the teardown callback, since that would try to start the
> + * remote processor device.
> + */
> + __cpuhp_remove_state(cpuhp_state, false);
> + cpuhp_state = 0;
> + }
> +
> + get_online_cpus();
> + /* Unregister devices created for any offline CPUs */
> + for_each_possible_cpu(cpu)
> + mips_rproc_device_unregister(cpu);
> + put_online_cpus();
> +}
> +
> +late_initcall(mips_rproc_init);
> +module_exit(mips_rproc_exit);
> +
> +module_platform_driver(mips_rproc_driver);
> +
> +MODULE_LICENSE("GPL v2");
> +MODULE_DESCRIPTION("MIPS Remote Processor control driver");

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