/*
* 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_phys_base() - Choose a physical base address for CDMM region.
*
* Picking a suitable physical address at which to map the CDMM region is
* platform specific, so this weak function can be overridden by platform
* code to pick a suitable value if none is configured by the bootloader.
*/
phys_addr_t __weak mips_cdmm_phys_base(void)
{
return 0;
}
/**
* 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)
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_cpu_down_prep() - Callback for CPUHP DOWN_PREP:
* Tear down the CDMM bus.
* @cpu: unsigned int CPU number.
*
* This function is executed on the hotplugged CPU and calls the CDMM
* driver cpu_down callback for all devices on that CPU.
*/
static int mips_cdmm_cpu_down_prep(unsigned int cpu)
{
struct mips_cdmm_bus *bus;
long ret;
/* Inform all the devices on the bus */
ret = bus_for_each_dev(&mips_cdmm_bustype, NULL, &cpu,
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_cpu_online() - Callback for CPUHP ONLINE: Bring up the CDMM bus.
* @cpu: 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 as work_on_cpu callback function during
* initialisation. When CPUs are brought online the function is
* invoked directly on the hotplugged CPU.
*/
static int mips_cdmm_cpu_online(unsigned int cpu)
{
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, &cpu,
mips_cdmm_cpu_up_helper);
return ret;
}
/**
* 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)
{
int ret;
/* Register the bus */
ret = bus_register(&mips_cdmm_bustype);
if (ret)
return ret;
/* We want to be notified about new CPUs */
ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "bus/cdmm:online",
mips_cdmm_cpu_online, mips_cdmm_cpu_down_prep);
if (ret < 0)
pr_warn("cdmm: Failed to register CPU notifier\n");
return ret;
}
subsys_initcall(mips_cdmm_init);
