Re: [PATCH 5/6] remoteproc/MIPS: Add a remoteproc driver for MIPS
From: Matt Redfearn
Date: Mon Sep 12 2016 - 04:50:06 EST
Hi,
Any feedback (or an ack) on this patch from Ohad or Bjorn would be much
appreciated!
Thanks,
Matt
On 02/09/16 10:59, 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 <lisa.parratt@xxxxxxxxxx>
Signed-off-by: Matt Redfearn <matt.redfearn@xxxxxxxxxx>
---
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 <lisa.parratt@xxxxxxxxxx>
+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 <lisa.parratt@xxxxxxxxxx>
+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 <lisa.parratt@xxxxxxxxxx>
+ * Matt Redfearn <matt.redfearn@xxxxxxxxxx>
+ *
+ * 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");