/* * 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/of_address.h>#include <linux/of.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_const(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, const struct device_driver *drv){	struct mips_cdmm_device *cdev = to_mips_cdmm_device(dev);	const struct mips_cdmm_driver *cdrv = to_mips_cdmm_driver(drv); 	return mips_cdmm_lookup(cdrv->id_table, cdev) != NULL;} static int mips_cdmm_uevent(const struct device *dev, struct kobj_uevent_env *env){	const 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); const 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_obj(*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. * By default this method tries to find a CDMM-specific node in the system * dtb. Note that this won't work for early serial console. */phys_addr_t __weak mips_cdmm_phys_base(void){	struct device_node *np;	struct resource res;	int err; 	np = of_find_compatible_node(NULL, NULL, "mti,mips-cdmm");	if (np) {		err = of_address_to_resource(np, 0, &res);		of_node_put(np);		if (!err)			return res.start;	} 	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.

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