--- /dev/null
+/*
+ * Bus driver for MIPS Common Device Memory Map (CDMM).
+ *
+ * Copyright (C) 2014-2015 Imagination Technologies Ltd.
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License. See the file "COPYING" in the main directory of this archive
+ * for more details.
+ */
+
+#include <linux/atomic.h>
+#include <linux/err.h>
+#include <linux/cpu.h>
+#include <linux/cpumask.h>
+#include <linux/io.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/smp.h>
+#include <asm/cdmm.h>
+#include <asm/hazards.h>
+#include <asm/mipsregs.h>
+
+/* Access control and status register fields */
+#define CDMM_ACSR_DEVTYPE_SHIFT 24
+#define CDMM_ACSR_DEVTYPE (255ul << CDMM_ACSR_DEVTYPE_SHIFT)
+#define CDMM_ACSR_DEVSIZE_SHIFT 16
+#define CDMM_ACSR_DEVSIZE (31ul << CDMM_ACSR_DEVSIZE_SHIFT)
+#define CDMM_ACSR_DEVREV_SHIFT 12
+#define CDMM_ACSR_DEVREV (15ul << CDMM_ACSR_DEVREV_SHIFT)
+#define CDMM_ACSR_UW (1ul << 3)
+#define CDMM_ACSR_UR (1ul << 2)
+#define CDMM_ACSR_SW (1ul << 1)
+#define CDMM_ACSR_SR (1ul << 0)
+
+/* Each block of device registers is 64 bytes */
+#define CDMM_DRB_SIZE 64
+
+#define to_mips_cdmm_driver(d) container_of(d, struct mips_cdmm_driver, drv)
+
+/* Default physical base address */
+static phys_addr_t mips_cdmm_default_base;
+
+/* Bus operations */
+
+static const struct mips_cdmm_device_id *
+mips_cdmm_lookup(const struct mips_cdmm_device_id *table,
+ struct mips_cdmm_device *dev)
+{
+ int ret = 0;
+
+ for (; table->type; ++table) {
+ ret = (dev->type == table->type);
+ if (ret)
+ break;
+ }
+
+ return ret ? table : NULL;
+}
+
+static int mips_cdmm_match(struct device *dev, struct device_driver *drv)
+{
+ struct mips_cdmm_device *cdev = to_mips_cdmm_device(dev);
+ struct mips_cdmm_driver *cdrv = to_mips_cdmm_driver(drv);
+
+ return mips_cdmm_lookup(cdrv->id_table, cdev) != NULL;
+}
+
+static int mips_cdmm_uevent(struct device *dev, struct kobj_uevent_env *env)
+{
+ struct mips_cdmm_device *cdev = to_mips_cdmm_device(dev);
+ int retval = 0;
+
+ retval = add_uevent_var(env, "CDMM_CPU=%u", cdev->cpu);
+ if (retval)
+ return retval;
+
+ retval = add_uevent_var(env, "CDMM_TYPE=0x%02x", cdev->type);
+ if (retval)
+ return retval;
+
+ retval = add_uevent_var(env, "CDMM_REV=%u", cdev->rev);
+ if (retval)
+ return retval;
+
+ retval = add_uevent_var(env, "MODALIAS=mipscdmm:t%02X", cdev->type);
+ return retval;
+}
+
+/* Device attributes */
+
+#define CDMM_ATTR(name, fmt, arg...) \
+static ssize_t name##_show(struct device *_dev, \
+ struct device_attribute *attr, char *buf) \
+{ \
+ struct mips_cdmm_device *dev = to_mips_cdmm_device(_dev); \
+ return sprintf(buf, fmt, arg); \
+} \
+static DEVICE_ATTR_RO(name);
+
+CDMM_ATTR(cpu, "%u\n", dev->cpu);
+CDMM_ATTR(type, "0x%02x\n", dev->type);
+CDMM_ATTR(revision, "%u\n", dev->rev);
+CDMM_ATTR(modalias, "mipscdmm:t%02X\n", dev->type);
+CDMM_ATTR(resource, "\t%016llx\t%016llx\t%016lx\n",
+ (unsigned long long)dev->res.start,
+ (unsigned long long)dev->res.end,
+ dev->res.flags);
+
+static struct attribute *mips_cdmm_dev_attrs[] = {
+ &dev_attr_cpu.attr,
+ &dev_attr_type.attr,
+ &dev_attr_revision.attr,
+ &dev_attr_modalias.attr,
+ &dev_attr_resource.attr,
+ NULL,
+};
+ATTRIBUTE_GROUPS(mips_cdmm_dev);
+
+struct bus_type mips_cdmm_bustype = {
+ .name = "cdmm",
+ .dev_groups = mips_cdmm_dev_groups,
+ .match = mips_cdmm_match,
+ .uevent = mips_cdmm_uevent,
+};
+EXPORT_SYMBOL_GPL(mips_cdmm_bustype);
+
+/*
+ * Standard driver callback helpers.
+ *
+ * All the CDMM driver callbacks need to be executed on the appropriate CPU from
+ * workqueues. For the standard driver callbacks we need a work function
+ * (mips_cdmm_{void,int}_work()) to do the actual call from the right CPU, and a
+ * wrapper function (generated with BUILD_PERCPU_HELPER) to arrange for the work
+ * function to be called on that CPU.
+ */
+
+/**
+ * struct mips_cdmm_work_dev - Data for per-device call work.
+ * @fn: CDMM driver callback function to call for the device.
+ * @dev: CDMM device to pass to @fn.
+ */
+struct mips_cdmm_work_dev {
+ void *fn;
+ struct mips_cdmm_device *dev;
+};
+
+/**
+ * mips_cdmm_void_work() - Call a void returning CDMM driver callback.
+ * @data: struct mips_cdmm_work_dev pointer.
+ *
+ * A work_on_cpu() callback function to call an arbitrary CDMM driver callback
+ * function which doesn't return a value.
+ */
+static long mips_cdmm_void_work(void *data)
+{
+ struct mips_cdmm_work_dev *work = data;
+ void (*fn)(struct mips_cdmm_device *) = work->fn;
+
+ fn(work->dev);
+ return 0;
+}
+
+/**
+ * mips_cdmm_int_work() - Call an int returning CDMM driver callback.
+ * @data: struct mips_cdmm_work_dev pointer.
+ *
+ * A work_on_cpu() callback function to call an arbitrary CDMM driver callback
+ * function which returns an int.
+ */
+static long mips_cdmm_int_work(void *data)
+{
+ struct mips_cdmm_work_dev *work = data;
+ int (*fn)(struct mips_cdmm_device *) = work->fn;
+
+ return fn(work->dev);
+}
+
+#define _BUILD_RET_void
+#define _BUILD_RET_int return
+
+/**
+ * BUILD_PERCPU_HELPER() - Helper to call a CDMM driver callback on right CPU.
+ * @_ret: Return type (void or int).
+ * @_name: Name of CDMM driver callback function.
+ *
+ * Generates a specific device callback function to call a CDMM driver callback
+ * function on the appropriate CPU for the device, and if applicable return the
+ * result.
+ */
+#define BUILD_PERCPU_HELPER(_ret, _name) \
+static _ret mips_cdmm_##_name(struct device *dev) \
+{ \
+ struct mips_cdmm_device *cdev = to_mips_cdmm_device(dev); \
+ struct mips_cdmm_driver *cdrv = to_mips_cdmm_driver(dev->driver); \
+ struct mips_cdmm_work_dev work = { \
+ .fn = cdrv->_name, \
+ .dev = cdev, \
+ }; \
+ \
+ _BUILD_RET_##_ret work_on_cpu(cdev->cpu, \
+ mips_cdmm_##_ret##_work, &work); \
+}
+
+/* Driver callback functions */
+BUILD_PERCPU_HELPER(int, probe) /* int mips_cdmm_probe(struct device) */
+BUILD_PERCPU_HELPER(int, remove) /* int mips_cdmm_remove(struct device) */
+BUILD_PERCPU_HELPER(void, shutdown) /* void mips_cdmm_shutdown(struct device) */
+
+
+/* Driver registration */
+
+/**
+ * mips_cdmm_driver_register() - Register a CDMM driver.
+ * @drv: CDMM driver information.
+ *
+ * Register a CDMM driver with the CDMM subsystem. The driver will be informed
+ * of matching devices which are discovered.
+ *
+ * Returns: 0 on success.
+ */
+int mips_cdmm_driver_register(struct mips_cdmm_driver *drv)
+{
+ drv->drv.bus = &mips_cdmm_bustype;
+
+ if (drv->probe)
+ drv->drv.probe = mips_cdmm_probe;
+ if (drv->remove)
+ drv->drv.remove = mips_cdmm_remove;
+ if (drv->shutdown)
+ drv->drv.shutdown = mips_cdmm_shutdown;
+
+ return driver_register(&drv->drv);
+}
+EXPORT_SYMBOL_GPL(mips_cdmm_driver_register);
+
+/**
+ * mips_cdmm_driver_unregister() - Unregister a CDMM driver.
+ * @drv: CDMM driver information.
+ *
+ * Unregister a CDMM driver from the CDMM subsystem.
+ */
+void mips_cdmm_driver_unregister(struct mips_cdmm_driver *drv)
+{
+ driver_unregister(&drv->drv);
+}
+EXPORT_SYMBOL_GPL(mips_cdmm_driver_unregister);
+
+
+/* CDMM initialisation and bus discovery */
+
+/**
+ * struct mips_cdmm_bus - Info about CDMM bus.
+ * @phys: Physical address at which it is mapped.
+ * @regs: Virtual address where registers can be accessed.
+ * @drbs: Total number of DRBs.
+ * @drbs_reserved: Number of DRBs reserved.
+ * @discovered: Whether the devices on the bus have been discovered yet.
+ * @offline: Whether the CDMM bus is going offline (or very early
+ * coming back online), in which case it should be
+ * reconfigured each time.
+ */
+struct mips_cdmm_bus {
+ phys_addr_t phys;
+ void __iomem *regs;
+ unsigned int drbs;
+ unsigned int drbs_reserved;
+ bool discovered;
+ bool offline;
+};
+
+static struct mips_cdmm_bus mips_cdmm_boot_bus;
+static DEFINE_PER_CPU(struct mips_cdmm_bus *, mips_cdmm_buses);
+static atomic_t mips_cdmm_next_id = ATOMIC_INIT(-1);
+
+/**
+ * mips_cdmm_get_bus() - Get the per-CPU CDMM bus information.
+ *
+ * Get information about the per-CPU CDMM bus, if the bus is present.
+ *
+ * The caller must prevent migration to another CPU, either by disabling
+ * pre-emption or by running from a pinned kernel thread.
+ *
+ * Returns: Pointer to CDMM bus information for the current CPU.
+ * May return ERR_PTR(-errno) in case of error, so check with
+ * IS_ERR().
+ */
+static struct mips_cdmm_bus *mips_cdmm_get_bus(void)
+{
+ struct mips_cdmm_bus *bus, **bus_p;
+ unsigned long flags;
+ unsigned int cpu;
+
+ if (!cpu_has_cdmm)
+ return ERR_PTR(-ENODEV);
+
+ cpu = smp_processor_id();
+ /* Avoid early use of per-cpu primitives before initialised */
+ if (cpu == 0)
+ return &mips_cdmm_boot_bus;
+
+ /* Get bus pointer */
+ bus_p = per_cpu_ptr(&mips_cdmm_buses, cpu);
+ local_irq_save(flags);
+ bus = *bus_p;
+ /* Attempt allocation if NULL */
+ if (unlikely(!bus)) {
+ bus = kzalloc(sizeof(*bus), GFP_ATOMIC);
+ if (unlikely(!bus))
+ bus = ERR_PTR(-ENOMEM);
+ else
+ *bus_p = bus;
+ }
+ local_irq_restore(flags);
+ return bus;
+}
+
+/**
+ * mips_cdmm_cur_base() - Find current physical base address of CDMM region.
+ *
+ * Returns: Physical base address of CDMM region according to cdmmbase CP0
+ * register, or 0 if the CDMM region is disabled.
+ */
+static phys_addr_t mips_cdmm_cur_base(void)
+{
+ unsigned long cdmmbase = read_c0_cdmmbase();
+
+ if (!(cdmmbase & MIPS_CDMMBASE_EN))
+ return 0;
+
+ return (cdmmbase >> MIPS_CDMMBASE_ADDR_SHIFT)
+ << MIPS_CDMMBASE_ADDR_START;
+}
+
+/**
+ * mips_cdmm_setup() - Ensure the CDMM bus is initialised and usable.
+ * @bus: Pointer to bus information for current CPU.
+ * IS_ERR(bus) is checked, so no need for caller to check.
+ *
+ * The caller must prevent migration to another CPU, either by disabling
+ * pre-emption or by running from a pinned kernel thread.
+ *
+ * Returns 0 on success, -errno on failure.
+ */
+static int mips_cdmm_setup(struct mips_cdmm_bus *bus)
+{
+ unsigned long cdmmbase, flags;
+ int ret = 0;
+
+ if (IS_ERR(bus))
+ return PTR_ERR(bus);
+
+ local_irq_save(flags);
+ /* Don't set up bus a second time unless marked offline */
+ if (bus->offline) {
+ /* If CDMM region is still set up, nothing to do */
+ if (bus->phys == mips_cdmm_cur_base())
+ goto out;
+ /*
+ * The CDMM region isn't set up as expected, so it needs
+ * reconfiguring, but then we can stop checking it.
+ */
+ bus->offline = false;
+ } else if (bus->phys > 1) {
+ goto out;
+ }
+
+ /* If the CDMM region is already configured, inherit that setup */
+ if (!bus->phys)
+ bus->phys = mips_cdmm_cur_base();
+ /* Otherwise, ask platform code for suggestions */
+ if (!bus->phys && mips_cdmm_phys_base)
+ bus->phys = mips_cdmm_phys_base();
+ /* Otherwise, copy what other CPUs have done */
+ if (!bus->phys)
+ bus->phys = mips_cdmm_default_base;
+ /* Otherwise, complain once */
+ if (!bus->phys) {
+ bus->phys = 1;
+ /*
+ * If you hit this, either your bootloader needs to set up the
+ * CDMM on the boot CPU, or else you need to implement
+ * mips_cdmm_phys_base() for your platform (see asm/cdmm.h).
+ */
+ pr_err("cdmm%u: Failed to choose a physical base\n",
+ smp_processor_id());
+ }
+ /* Already complained? */
+ if (bus->phys == 1) {
+ ret = -ENOMEM;
+ goto out;
+ }
+ /* Record our success for other CPUs to copy */
+ mips_cdmm_default_base = bus->phys;
+
+ pr_debug("cdmm%u: Enabling CDMM region at %pa\n",
+ smp_processor_id(), &bus->phys);
+
+ /* Enable CDMM */
+ cdmmbase = read_c0_cdmmbase();
+ cdmmbase &= (1ul << MIPS_CDMMBASE_ADDR_SHIFT) - 1;
+ cdmmbase |= (bus->phys >> MIPS_CDMMBASE_ADDR_START)
+ << MIPS_CDMMBASE_ADDR_SHIFT;
+ cdmmbase |= MIPS_CDMMBASE_EN;
+ write_c0_cdmmbase(cdmmbase);
+ tlbw_use_hazard();
+
+ bus->regs = (void __iomem *)CKSEG1ADDR(bus->phys);
+ bus->drbs = 1 + ((cdmmbase & MIPS_CDMMBASE_SIZE) >>
+ MIPS_CDMMBASE_SIZE_SHIFT);
+ bus->drbs_reserved = !!(cdmmbase & MIPS_CDMMBASE_CI);
+
+out:
+ local_irq_restore(flags);
+ return ret;
+}
+
+/**
+ * mips_cdmm_early_probe() - Minimally probe for a specific device on CDMM.
+ * @dev_type: CDMM type code to look for.
+ *
+ * Minimally configure the in-CPU Common Device Memory Map (CDMM) and look for a
+ * specific device. This can be used to find a device very early in boot for
+ * example to configure an early FDC console device.
+ *
+ * The caller must prevent migration to another CPU, either by disabling
+ * pre-emption or by running from a pinned kernel thread.
+ *
+ * Returns: MMIO pointer to device memory. The caller can read the ACSR
+ * register to find more information about the device (such as the
+ * version number or the number of blocks).
+ * May return IOMEM_ERR_PTR(-errno) in case of error, so check with
+ * IS_ERR().
+ */
+void __iomem *mips_cdmm_early_probe(unsigned int dev_type)
+{
+ struct mips_cdmm_bus *bus;
+ void __iomem *cdmm;
+ u32 acsr;
+ unsigned int drb, type, size;
+ int err;
+
+ if (WARN_ON(!dev_type))
+ return IOMEM_ERR_PTR(-ENODEV);
+
+ bus = mips_cdmm_get_bus();
+ err = mips_cdmm_setup(bus);
+ if (err)
+ return IOMEM_ERR_PTR(err);
+
+ /* Skip the first block if it's reserved for more registers */
+ drb = bus->drbs_reserved;
+ cdmm = bus->regs;
+
+ /* Look for a specific device type */
+ for (; drb < bus->drbs; drb += size + 1) {
+ acsr = __raw_readl(cdmm + drb * CDMM_DRB_SIZE);
+ type = (acsr & CDMM_ACSR_DEVTYPE) >> CDMM_ACSR_DEVTYPE_SHIFT;
+ if (type == dev_type)
+ return cdmm + drb * CDMM_DRB_SIZE;
+ size = (acsr & CDMM_ACSR_DEVSIZE) >> CDMM_ACSR_DEVSIZE_SHIFT;
+ }
+
+ return IOMEM_ERR_PTR(-ENODEV);
+}
+EXPORT_SYMBOL_GPL(mips_cdmm_early_probe);
+
+/**
+ * mips_cdmm_release() - Release a removed CDMM device.
+ * @dev: Device object
+ *
+ * Clean up the struct mips_cdmm_device for an unused CDMM device. This is
+ * called automatically by the driver core when a device is removed.
+ */
+static void mips_cdmm_release(struct device *dev)
+{
+ struct mips_cdmm_device *cdev = to_mips_cdmm_device(dev);
+
+ kfree(cdev);
+}
+
+/**
+ * mips_cdmm_bus_discover() - Discover the devices on the CDMM bus.
+ * @bus: CDMM bus information, must already be set up.
+ */
+static void mips_cdmm_bus_discover(struct mips_cdmm_bus *bus)
+{
+ void __iomem *cdmm;
+ u32 acsr;
+ unsigned int drb, type, size, rev;
+ struct mips_cdmm_device *dev;
+ unsigned int cpu = smp_processor_id();
+ int ret = 0;
+ int id = 0;
+
+ /* Skip the first block if it's reserved for more registers */
+ drb = bus->drbs_reserved;
+ cdmm = bus->regs;
+
+ /* Discover devices */
+ bus->discovered = true;
+ pr_info("cdmm%u discovery (%u blocks)\n", cpu, bus->drbs);
+ for (; drb < bus->drbs; drb += size + 1) {
+ acsr = __raw_readl(cdmm + drb * CDMM_DRB_SIZE);
+ type = (acsr & CDMM_ACSR_DEVTYPE) >> CDMM_ACSR_DEVTYPE_SHIFT;
+ size = (acsr & CDMM_ACSR_DEVSIZE) >> CDMM_ACSR_DEVSIZE_SHIFT;
+ rev = (acsr & CDMM_ACSR_DEVREV) >> CDMM_ACSR_DEVREV_SHIFT;
+
+ if (!type)
+ continue;
+
+ pr_info("cdmm%u-%u: @%u (%#x..%#x), type 0x%02x, rev %u\n",
+ cpu, id, drb, drb * CDMM_DRB_SIZE,
+ (drb + size + 1) * CDMM_DRB_SIZE - 1,
+ type, rev);
+
+ dev = kzalloc(sizeof(*dev), GFP_KERNEL);
+ if (!dev)
+ break;
+
+ dev->cpu = cpu;
+ dev->res.start = bus->phys + drb * CDMM_DRB_SIZE;
+ dev->res.end = bus->phys +
+ (drb + size + 1) * CDMM_DRB_SIZE - 1;
+ dev->res.flags = IORESOURCE_MEM;
+ dev->type = type;
+ dev->rev = rev;
+ dev->dev.parent = get_cpu_device(cpu);
+ dev->dev.bus = &mips_cdmm_bustype;
+ dev->dev.id = atomic_inc_return(&mips_cdmm_next_id);
+ dev->dev.release = mips_cdmm_release;
+
+ dev_set_name(&dev->dev, "cdmm%u-%u", cpu, id);
+ ++id;
+ ret = device_register(&dev->dev);
+ if (ret) {
+ put_device(&dev->dev);
+ kfree(dev);
+ }
+ }
+}
+
+
+/*
+ * CPU hotplug and initialisation
+ *
+ * All the CDMM driver callbacks need to be executed on the appropriate CPU from
+ * workqueues. For the CPU callbacks, they need to be called for all devices on
+ * that CPU, so the work function calls bus_for_each_dev, using a helper
+ * (generated with BUILD_PERDEV_HELPER) to call the driver callback if the
+ * device's CPU matches.
+ */
+
+/**
+ * BUILD_PERDEV_HELPER() - Helper to call a CDMM driver callback if CPU matches.
+ * @_name: Name of CDMM driver callback function.
+ *
+ * Generates a bus_for_each_dev callback function to call a specific CDMM driver
+ * callback function for the device if the device's CPU matches that pointed to
+ * by the data argument.
+ *
+ * This is used for informing drivers for all devices on a given CPU of some
+ * event (such as the CPU going online/offline).
+ *
+ * It is expected to already be called from the appropriate CPU.
+ */
+#define BUILD_PERDEV_HELPER(_name) \
+static int mips_cdmm_##_name##_helper(struct device *dev, void *data) \
+{ \
+ struct mips_cdmm_device *cdev = to_mips_cdmm_device(dev); \
+ struct mips_cdmm_driver *cdrv; \
+ unsigned int cpu = *(unsigned int *)data; \
+ \
+ if (cdev->cpu != cpu || !dev->driver) \
+ return 0; \
+ \
+ cdrv = to_mips_cdmm_driver(dev->driver); \
+ if (!cdrv->_name) \
+ return 0; \
+ return cdrv->_name(cdev); \
+}
+
+/* bus_for_each_dev callback helper functions */
+BUILD_PERDEV_HELPER(cpu_down) /* int mips_cdmm_cpu_down_helper(...) */
+BUILD_PERDEV_HELPER(cpu_up) /* int mips_cdmm_cpu_up_helper(...) */
+
+/**
+ * mips_cdmm_bus_down() - Tear down the CDMM bus.
+ * @data: Pointer to unsigned int CPU number.
+ *
+ * This work_on_cpu callback function is executed on a given CPU to call the
+ * CDMM driver cpu_down callback for all devices on that CPU.
+ */
+static long mips_cdmm_bus_down(void *data)
+{
+ struct mips_cdmm_bus *bus;
+ long ret;
+
+ /* Inform all the devices on the bus */
+ ret = bus_for_each_dev(&mips_cdmm_bustype, NULL, data,
+ mips_cdmm_cpu_down_helper);
+
+ /*
+ * While bus is offline, each use of it should reconfigure it just in
+ * case it is first use when coming back online again.
+ */
+ bus = mips_cdmm_get_bus();
+ if (!IS_ERR(bus))
+ bus->offline = true;
+
+ return ret;
+}
+
+/**
+ * mips_cdmm_bus_up() - Bring up the CDMM bus.
+ * @data: Pointer to unsigned int CPU number.
+ *
+ * This work_on_cpu callback function is executed on a given CPU to discover
+ * CDMM devices on that CPU, or to call the CDMM driver cpu_up callback for all
+ * devices already discovered on that CPU.
+ *
+ * It is used during initialisation and when CPUs are brought online.
+ */
+static long mips_cdmm_bus_up(void *data)
+{
+ struct mips_cdmm_bus *bus;
+ long ret;
+
+ bus = mips_cdmm_get_bus();
+ ret = mips_cdmm_setup(bus);
+ if (ret)
+ return ret;
+
+ /* Bus now set up, so we can drop the offline flag if still set */
+ bus->offline = false;
+
+ if (!bus->discovered)
+ mips_cdmm_bus_discover(bus);
+ else
+ /* Inform all the devices on the bus */
+ ret = bus_for_each_dev(&mips_cdmm_bustype, NULL, data,
+ mips_cdmm_cpu_up_helper);
+
+ return ret;
+}
+
+/**
+ * mips_cdmm_cpu_notify() - Take action when a CPU is going online or offline.
+ * @nb: CPU notifier block .
+ * @action: Event that has taken place (CPU_*).
+ * @data: CPU number.
+ *
+ * This notifier is used to keep the CDMM buses updated as CPUs are offlined and
+ * onlined. When CPUs go offline or come back online, so does their CDMM bus, so
+ * devices must be informed. Also when CPUs come online for the first time the
+ * devices on the CDMM bus need discovering.
+ *
+ * Returns: NOTIFY_OK if event was used.
+ * NOTIFY_DONE if we didn't care.
+ */
+static int mips_cdmm_cpu_notify(struct notifier_block *nb,
+ unsigned long action, void *data)
+{
+ unsigned int cpu = (unsigned int)data;
+
+ switch (action & ~CPU_TASKS_FROZEN) {
+ case CPU_ONLINE:
+ case CPU_DOWN_FAILED:
+ work_on_cpu(cpu, mips_cdmm_bus_up, &cpu);
+ break;
+ case CPU_DOWN_PREPARE:
+ work_on_cpu(cpu, mips_cdmm_bus_down, &cpu);
+ break;
+ default:
+ return NOTIFY_DONE;
+ }
+
+ return NOTIFY_OK;
+}
+
+static struct notifier_block mips_cdmm_cpu_nb = {
+ .notifier_call = mips_cdmm_cpu_notify,
+};
+
+/**
+ * mips_cdmm_init() - Initialise CDMM bus.
+ *
+ * Initialise CDMM bus, discover CDMM devices for online CPUs, and arrange for
+ * hotplug notifications so the CDMM drivers can be kept up to date.
+ */
+static int __init mips_cdmm_init(void)
+{
+ unsigned int cpu;
+ int ret;
+
+ /* Register the bus */
+ ret = bus_register(&mips_cdmm_bustype);
+ if (ret)
+ return ret;
+
+ /* We want to be notified about new CPUs */
+ ret = register_cpu_notifier(&mips_cdmm_cpu_nb);
+ if (ret) {
+ pr_warn("cdmm: Failed to register CPU notifier\n");
+ goto out;
+ }
+
+ /* Discover devices on CDMM of online CPUs */
+ for_each_online_cpu(cpu)
+ work_on_cpu(cpu, mips_cdmm_bus_up, &cpu);
+
+ return 0;
+out:
+ bus_unregister(&mips_cdmm_bustype);
+ return ret;
+}
+subsys_initcall(mips_cdmm_init);
Code Review / kvmfornfv.git / blobdiff