diff options
Diffstat (limited to 'drivers/bus')
| -rw-r--r-- | drivers/bus/Kconfig | 13 | ||||
| -rw-r--r-- | drivers/bus/Makefile | 1 | ||||
| -rw-r--r-- | drivers/bus/mips_cdmm.c | 716 |
3 files changed, 730 insertions, 0 deletions
diff --git a/drivers/bus/Kconfig b/drivers/bus/Kconfig index b99729e36860..cbddbaddb347 100644 --- a/drivers/bus/Kconfig +++ b/drivers/bus/Kconfig @@ -20,6 +20,19 @@ config IMX_WEIM The WEIM(Wireless External Interface Module) works like a bus. You can attach many different devices on it, such as NOR, onenand. +config MIPS_CDMM + bool "MIPS Common Device Memory Map (CDMM) Driver" + depends on CPU_MIPSR2 + help + Driver needed for the MIPS Common Device Memory Map bus in MIPS + cores. This bus is for per-CPU tightly coupled devices such as the + Fast Debug Channel (FDC). + + For this to work, either your bootloader needs to enable the CDMM + region at an unused physical address on the boot CPU, or else your + platform code needs to implement mips_cdmm_phys_base() (see + asm/cdmm.h). + config MVEBU_MBUS bool depends on PLAT_ORION diff --git a/drivers/bus/Makefile b/drivers/bus/Makefile index 2973c18cbcc2..807dd17ef2f8 100644 --- a/drivers/bus/Makefile +++ b/drivers/bus/Makefile @@ -4,6 +4,7 @@ obj-$(CONFIG_BRCMSTB_GISB_ARB) += brcmstb_gisb.o obj-$(CONFIG_IMX_WEIM) += imx-weim.o +obj-$(CONFIG_MIPS_CDMM) += mips_cdmm.o obj-$(CONFIG_MVEBU_MBUS) += mvebu-mbus.o obj-$(CONFIG_OMAP_OCP2SCP) += omap-ocp2scp.o diff --git a/drivers/bus/mips_cdmm.c b/drivers/bus/mips_cdmm.c new file mode 100644 index 000000000000..5bd792c68f9b --- /dev/null +++ b/drivers/bus/mips_cdmm.c @@ -0,0 +1,716 @@ +/* + * 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 = 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 = 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); |