Hi Bjorn / Ohad,
Please could you give some feedback on this patch?
Thanks,
Matt
On 20/09/16 09:47, Matt Redfearn wrote:
> Add a remoteproc driver to steal, load the firmware, and boot an offline
> MIPS core, turning it into a coprocessor.
>
> This driver provides a sysfs to allow arbitrary firmware to be loaded
> onto a core, which may expose virtio devices. Coprocessor firmware must
> abide by the UHI coprocessor boot protocol.
>
> Signed-off-by: Lisa Parratt <[email protected]>
> Signed-off-by: Matt Redfearn <[email protected]>
>
> ---
>
> Changes in v2: None
>
> Documentation/ABI/testing/sysfs-class-mips-rproc | 24 +
> drivers/remoteproc/Kconfig | 11 +
> drivers/remoteproc/Makefile | 1 +
> drivers/remoteproc/mips_remoteproc.c | 651 +++++++++++++++++++++++
> 4 files changed, 687 insertions(+)
> create mode 100644 Documentation/ABI/testing/sysfs-class-mips-rproc
> create mode 100644 drivers/remoteproc/mips_remoteproc.c
>
> diff --git a/Documentation/ABI/testing/sysfs-class-mips-rproc b/Documentation/ABI/testing/sysfs-class-mips-rproc
> new file mode 100644
> index 000000000000..c09d02a755e4
> --- /dev/null
> +++ b/Documentation/ABI/testing/sysfs-class-mips-rproc
> @@ -0,0 +1,24 @@
> +What: /sys/class/mips-rproc/rproc#/firmware
> +Date: August 2015
> +Contact: Lisa Parratt <[email protected]>
> +Description: MIPS VPE remoteproc start
> +
> + This node only exists when a VPE is considered offline by Linux. Writes
> + to this file will start firmware running on a VPE.
> +
> + If the VPE is idle, specifying a name will cause a remoteproc instance
> + to be allocated, which will cause the core to be stolen, the firmware
> + image to be loaded, and the remoteproc instance to be started.
> + Otherwise, the operation will fail.
> +
> +What: /sys/class/mips-rproc/rproc#/stop
> +Date: August 2015
> +Contact: Lisa Parratt <[email protected]>
> +Description: MIPS VPE remoteproc stop
> +
> + This node only exists when a VPE is considered offline by Linux. Writes
> + to this file will stop firmware running on a VPE.
> +
> + If the VPE is running a remote proc instance, the instance will be
> + stopped, the core returned, and the instance freed.
> + Otherwise, the operation will fail.
> diff --git a/drivers/remoteproc/Kconfig b/drivers/remoteproc/Kconfig
> index 1a8bf76a925f..05db52e0e668 100644
> --- a/drivers/remoteproc/Kconfig
> +++ b/drivers/remoteproc/Kconfig
> @@ -100,4 +100,15 @@ config ST_REMOTEPROC
> processor framework.
> This can be either built-in or a loadable module.
>
> +config MIPS_REMOTEPROC
> + tristate "MIPS remoteproc support"
> + depends on MIPS_CPS && HAS_DMA
> + select CMA
> + select REMOTEPROC
> + select MIPS_STEAL
> + help
> + Say y here to support using offline cores/VPEs as remote processors
> + via the remote processor framework.
> + If unsure say N.
> +
> endmenu
> diff --git a/drivers/remoteproc/Makefile b/drivers/remoteproc/Makefile
> index 92d3758bd15c..de19cd320f3a 100644
> --- a/drivers/remoteproc/Makefile
> +++ b/drivers/remoteproc/Makefile
> @@ -14,3 +14,4 @@ obj-$(CONFIG_DA8XX_REMOTEPROC) += da8xx_remoteproc.o
> obj-$(CONFIG_QCOM_MDT_LOADER) += qcom_mdt_loader.o
> obj-$(CONFIG_QCOM_Q6V5_PIL) += qcom_q6v5_pil.o
> obj-$(CONFIG_ST_REMOTEPROC) += st_remoteproc.o
> +obj-$(CONFIG_MIPS_REMOTEPROC) += mips_remoteproc.o
> diff --git a/drivers/remoteproc/mips_remoteproc.c b/drivers/remoteproc/mips_remoteproc.c
> new file mode 100644
> index 000000000000..944ad66280b4
> --- /dev/null
> +++ b/drivers/remoteproc/mips_remoteproc.c
> @@ -0,0 +1,651 @@
> +/*
> + * MIPS Remote Processor driver
> + *
> + * Copyright (C) 2016 Imagination Technologies
> + * Lisa Parratt <[email protected]>
> + * Matt Redfearn <[email protected]>
> + *
> + * 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/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/dma-coherence.h>
> +#include <asm/smp-cps.h>
> +#include <asm/tlbflush.h>
> +#include <asm/tlbmisc.h>
> +
> +#include "remoteproc_internal.h"
> +
> +struct mips_rproc {
> + struct rproc *rproc;
> + char *firmware;
> + struct task_struct *tsk;
> + struct device dev;
> + unsigned int cpu;
> + int ipi_linux;
> + int ipi_remote;
> +};
> +
> +static struct rproc *mips_rprocs[NR_CPUS];
> +
> +#define to_mips_rproc(d) container_of(d, struct mips_rproc, dev)
> +
> +
> +/* 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 next largest page mask for a given page mask */
> +static unsigned long mips_rproc_next_pm(unsigned long pm, unsigned long maxmask)
> +{
> + if (pm != PM_4K)
> + return ((pm << 2) | pm) & maxmask;
> + else
> + return PM_16K;
> +}
> +
> +static void mips_map_page(unsigned long da, unsigned long pa, int c,
> + unsigned long pagemask, unsigned long pagesize)
> +{
> + unsigned long pa2 = pa + (pagesize / 2);
> + unsigned long entryhi, entrylo0, entrylo1;
> +
> + /* Compute the mapping */
> + 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 page required to fulfill a mapping. Escapes alignment derived
> + * page size limitations before using biggest fit to map the remainder.
> + */
> +static inline void mips_rproc_fit_page(unsigned long da, unsigned long pa,
> + int c, unsigned long size,
> + unsigned long maxmask)
> +{
> + unsigned long bigmask, nextmask;
> + unsigned long pagemask, pagesize;
> + unsigned long distance, target;
> +
> + 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 + 0x2000) - (pa & nextmask);
> + /*
> + * Decide between searching to get to the next highest page
> + * boundary or finishing.
> + */
> + target = distance < size ? distance : size;
> + /* Fit */
> + while (target) {
> + /* Find the largest supported page size that will fit */
> + for (pagesize = maxmask + 0x2000;
> + (pagesize > 0x2000) && (pagesize > target);
> + pagesize /= 4) {
> + }
> + /* Convert it to a page mask */
> + pagemask = pagesize - 0x2000;
> + /* Emit it */
> + mips_map_page(da, pa, c, pagemask, pagesize);
> + /* Move to next step */
> + size -= pagesize;
> + da += pagesize;
> + pa += pagesize;
> + target -= pagesize;
> + }
> + } 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_fit_page(carveout->da, carveout->dma, c,
> + carveout->len, max_pagemask);
> + }
> + 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 (hw_coherentio) {
> + /*
> + * 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_fit_page(pa, pa, c, size, max_pagemask);
> + }
> + }
> + return 0;
> +}
> +
> +static void mips_rproc_cpu_entry(void)
> +{
> + struct rproc *rproc = mips_rprocs[smp_processor_id()];
> + struct mips_rproc *mproc = *(struct mips_rproc **)rproc->priv;
> + 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;
> +
> + if (!rproc)
> + return;
> +
> + dev_info(&rproc->dev, "Starting %s on MIPS CPU%d\n",
> + mproc->firmware, mproc->cpu);
> +
> + /* Get the maximum pagemask supported on this CPU */
> + old_pagemask = read_c0_pagemask();
> + write_c0_pagemask(PM_HUGE_MASK);
> + mtc0_tlbw_hazard();
> + max_pagemask = read_c0_pagemask();
> + write_c0_pagemask(old_pagemask);
> + mtc0_tlbw_hazard();
> +
> + /* Start with no wired entries */
> + write_c0_wired(0);
> +
> + /* Flush all previous TLB entries */
> + local_flush_tlb_all();
> +
> + /* 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);
> +
> + write_c0_entryhi(0); /* Set ASID 0 */
> + tlbw_use_hazard();
> +
> + /* Firmware protocol */
> + __asm__("addiu $a0, $zero, -3");
> + __asm__("move $a1, %0" :: "r" (ipi_to_remote));
> + __asm__("move $a2, %0" :: "r" (ipi_from_remote));
> + __asm__("move $a3, $zero");
> + __asm__("jr %0" :: "r" (rproc->bootaddr));
> +}
> +
> +
> +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 = *(struct mips_rproc **)rproc->priv;
> + int err;
> + int cpu = mproc->cpu;
> +
> + if (mips_rprocs[cpu]) {
> + dev_err(&rproc->dev, "CPU%d in use\n", cpu);
> + return -EBUSY;
> + }
> + mips_rprocs[cpu] = rproc;
> +
> + /* 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)))
> + return -EINVAL;
> +
> + /*
> + * 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(&mproc->dev, "Failed to reserve incoming kick\n");
> + goto exit_rproc_nofrom;
> + }
> +
> + mproc->ipi_remote = irq_reserve_ipi(ipi_domain(), get_cpu_mask(cpu));
> + if (!mproc->ipi_remote) {
> + dev_err(&mproc->dev, "Failed to reserve outgoing kick\n");
> + goto exit_rproc_noto;
> + }
> +
> + /* register incoming ipi */
> + err = devm_request_threaded_irq(&mproc->dev, mproc->ipi_linux,
> + mips_rproc_ipi_handler,
> + mips_rproc_vq_int, 0,
> + "mips-rproc IPI in", mproc->rproc);
> + if (err) {
> + dev_err(&mproc->dev, "Failed to register incoming kick: %d\n",
> + err);
> + goto exit_rproc_noint;
> + }
> +
> + if (!mips_cps_steal_cpu_and_execute(cpu, &mips_rproc_cpu_entry,
> + mproc->tsk))
> + return 0;
> +
> + dev_err(&mproc->dev, "Failed to steal CPU%d for remote\n", cpu);
> + devm_free_irq(&mproc->dev, mproc->ipi_linux, mproc->rproc);
> +exit_rproc_noint:
> + irq_destroy_ipi(mproc->ipi_remote, get_cpu_mask(cpu));
> +exit_rproc_noto:
> + irq_destroy_ipi(mproc->ipi_linux, get_cpu_mask(0));
> +exit_rproc_nofrom:
> + free_task(mproc->tsk);
> + mips_rprocs[cpu] = NULL;
> +
> + /* Set up the Linux IPIs again */
> + mips_smp_ipi_allocate(get_cpu_mask(cpu));
> + return -EINVAL;
> +}
> +
> +int mips_rproc_op_stop(struct rproc *rproc)
> +{
> + struct mips_rproc *mproc = *(struct mips_rproc **)rproc->priv;
> +
> + if (mproc->ipi_linux)
> + devm_free_irq(&mproc->dev, mproc->ipi_linux, mproc->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));
> +
> + free_task(mproc->tsk);
> +
> + mips_rprocs[mproc->cpu] = NULL;
> +
> + return mips_cps_halt_and_return_cpu(mproc->cpu);
> +}
> +
> +
> +void mips_rproc_op_kick(struct rproc *rproc, int vqid)
> +{
> + struct mips_rproc *mproc = *(struct mips_rproc **)rproc->priv;
> +
> + ipi_send_single(mproc->ipi_remote, mproc->cpu);
> +}
> +
> +struct rproc_ops mips_rproc_proc_ops = {
> + .start = mips_rproc_op_start,
> + .stop = mips_rproc_op_stop,
> + .kick = mips_rproc_op_kick,
> +};
> +
> +
> +static int mips_rproc_probe(struct platform_device *pdev)
> +{
> + return 0;
> +}
> +
> +static int mips_rproc_remove(struct platform_device *pdev)
> +{
> + return 0;
> +}
> +
> +static struct platform_driver mips_rproc_driver = {
> + .probe = mips_rproc_probe,
> + .remove = mips_rproc_remove,
> + .driver = {
> + .name = "mips-rproc"
> + },
> +};
> +
> +
> +/* Steal a core and run some firmware on it */
> +int mips_rproc_start(struct mips_rproc *mproc, const char *firmware, size_t len)
> +{
> + int err = -EINVAL;
> + struct mips_rproc **priv;
> +
> + /* Duplicate the filename, dropping whitespace from the end via len */
> + mproc->firmware = kstrndup(firmware, len, GFP_KERNEL);
> + if (!mproc->firmware)
> + return -ENOMEM;
> +
> + mproc->rproc = rproc_alloc(&mproc->dev, "mips", &mips_rproc_proc_ops,
> + mproc->firmware,
> + sizeof(struct mips_rproc *));
> + if (!mproc->rproc)
> + return -ENOMEM;
> +
> + priv = mproc->rproc->priv;
> + *priv = mproc;
> +
> + /* go live! */
> + err = rproc_add(mproc->rproc);
> + if (err) {
> + dev_err(&mproc->dev, "Failed to add rproc: %d\n", err);
> + rproc_put(mproc->rproc);
> + kfree(mproc->firmware);
> + return -EINVAL;
> + }
> +
> + return 0;
> +}
> +
> +/* Stop a core, and return it to being offline */
> +int mips_rproc_stop(struct mips_rproc *mproc)
> +{
> + rproc_shutdown(mproc->rproc);
> + rproc_del(mproc->rproc);
> + rproc_put(mproc->rproc);
> + mproc->rproc = NULL;
> + return 0;
> +}
> +
> +/* sysfs interface to mips_rproc_start */
> +static ssize_t firmware_store(struct device *dev,
> + struct device_attribute *attr,
> + const char *buf, size_t count)
> +{
> + struct mips_rproc *mproc = to_mips_rproc(dev);
> + size_t len = count;
> + int err = -EINVAL;
> +
> + if (buf[count - 1] == '\n')
> + len--;
> +
> + if (!mproc->rproc && len)
> + err = mips_rproc_start(mproc, buf, len);
> + else if (len)
> + err = -EBUSY;
> +
> + return err ? err : count;
> +}
> +static DEVICE_ATTR_WO(firmware);
> +
> +/* sysfs interface to mips_rproc_stop */
> +static ssize_t stop_store(struct device *dev,
> + struct device_attribute *attr,
> + const char *buf, size_t count)
> +{
> + struct mips_rproc *mproc = to_mips_rproc(dev);
> + int err = -EINVAL;
> +
> +
> + if (mproc->rproc)
> + err = mips_rproc_stop(mproc);
> + else
> + err = -EBUSY;
> +
> + return err ? err : count;
> +}
> +static DEVICE_ATTR_WO(stop);
> +
> +/* Boiler plate for devclarng mips-rproc sysfs devices */
> +static struct attribute *mips_rproc_attrs[] = {
> + &dev_attr_firmware.attr,
> + &dev_attr_stop.attr,
> + NULL
> +};
> +
> +static struct attribute_group mips_rproc_devgroup = {
> + .attrs = mips_rproc_attrs
> +};
> +
> +static const struct attribute_group *mips_rproc_devgroups[] = {
> + &mips_rproc_devgroup,
> + NULL
> +};
> +
> +static char *mips_rproc_devnode(struct device *dev, umode_t *mode)
> +{
> + return kasprintf(GFP_KERNEL, "mips-rproc/%s", dev_name(dev));
> +}
> +
> +static struct class mips_rproc_class = {
> + .name = "mips-rproc",
> + .devnode = mips_rproc_devnode,
> + .dev_groups = mips_rproc_devgroups,
> +};
> +
> +static void mips_rproc_release(struct device *dev)
> +{
> +}
> +
> +static int mips_rproc_uevent(struct device *dev, struct kobj_uevent_env *env)
> +{
> + struct mips_rproc *mproc = to_mips_rproc(dev);
> +
> + if (!mproc)
> + return -ENODEV;
> +
> + return 0;
> +}
> +
> +static struct device_type mips_rproc_type = {
> + .release = mips_rproc_release,
> + .uevent = mips_rproc_uevent
> +};
> +
> +/* Helper function for locating the device for a CPU */
> +int mips_rproc_device_rproc_match(struct device *dev, const void *data)
> +{
> + struct mips_rproc *mproc = to_mips_rproc(dev);
> + unsigned int cpu = *(unsigned int *)data;
> +
> + return mproc->cpu == cpu;
> +}
> +
> +/* Create a sysfs device in response to CPU down */
> +int mips_rproc_device_register(unsigned int cpu)
> +{
> + struct mips_rproc *dev;
> +
> + dev = kzalloc(sizeof(*dev), GFP_KERNEL);
> + if (!dev)
> + return -EINVAL;
> +
> + dev->dev.driver = &mips_rproc_driver.driver;
> + dev->dev.type = &mips_rproc_type;
> + dev->dev.class = &mips_rproc_class;
> + dev->dev.id = cpu;
> + dev_set_name(&dev->dev, "rproc%u", cpu);
> + dev->cpu = cpu;
> +
> + return device_register(&dev->dev);
> +}
> +
> +/* Destroy a sysfs device in response to CPU up */
> +int mips_rproc_device_unregister(unsigned int cpu)
> +{
> + struct device *dev = class_find_device(&mips_rproc_class, NULL, &cpu,
> + mips_rproc_device_rproc_match);
> + struct mips_rproc *mproc = to_mips_rproc(dev);
> +
> + if (mips_rprocs[cpu])
> + mips_rproc_stop(mproc);
> +
> + put_device(dev);
> + device_unregister(dev);
> + kfree(mproc);
> + return 0;
> +}
> +
> +/* Intercept CPU hotplug events for syfs purposes */
> +static int mips_rproc_callback(struct notifier_block *nfb, unsigned long action,
> + void *hcpu)
> +{
> + unsigned int cpu = (unsigned long)hcpu;
> +
> + switch (action) {
> + case CPU_UP_PREPARE:
> + case CPU_DOWN_FAILED:
> + mips_rproc_device_unregister(cpu);
> + break;
> + case CPU_DOWN_PREPARE:
> + mips_rproc_device_register(cpu);
> + break;
> + }
> +
> + return NOTIFY_OK;
> +}
> +
> +static struct notifier_block mips_rproc_notifier __refdata = {
> + .notifier_call = mips_rproc_callback
> +};
> +
> +static int __init mips_rproc_init(void)
> +{
> + int cpu;
> + /* create mips-rproc device class for sysfs */
> + int err = class_register(&mips_rproc_class);
> +
> + if (err) {
> + pr_err("mips-proc: unable to register mips-rproc class\n");
> + return err;
> + }
> +
> + /* Dynamically create mips-rproc class devices based on hotplug data */
> + get_online_cpus();
> + for_each_possible_cpu(cpu)
> + if (!cpu_online(cpu))
> + mips_rproc_device_register(cpu);
> + register_hotcpu_notifier(&mips_rproc_notifier);
> + put_online_cpus();
> +
> + return 0;
> +}
> +
> +static void __exit mips_rproc_exit(void)
> +{
> + int cpu;
> + /* Destroy mips-rproc class devices */
> + get_online_cpus();
> + unregister_hotcpu_notifier(&mips_rproc_notifier);
> + for_each_possible_cpu(cpu)
> + if (!cpu_online(cpu))
> + mips_rproc_device_unregister(cpu);
> + put_online_cpus();
> +
> + class_unregister(&mips_rproc_class);
> +}
> +
> +subsys_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");