platform.c

linux 内核源代码

/**
 *	platform_device_unregister - unregister a platform-level device
 *	@pdev:	platform device we're unregistering
 *
 *	Unregistration is done in 2 steps. First we release all resources
 *	and remove it from the subsystem, then we drop reference count by
 *	calling platform_device_put().
 */
void platform_device_unregister(struct platform_device * pdev)
{
	platform_device_del(pdev);
	platform_device_put(pdev);
}
EXPORT_SYMBOL_GPL(platform_device_unregister);

/**
 *	platform_device_register_simple
 *	@name:  base name of the device we're adding
 *	@id:    instance id
 *	@res:   set of resources that needs to be allocated for the device
 *	@num:	number of resources
 *
 *	This function creates a simple platform device that requires minimal
 *	resource and memory management. Canned release function freeing
 *	memory allocated for the device allows drivers using such devices
 *	to be unloaded without waiting for the last reference to the device
 *	to be dropped.
 *
 *	This interface is primarily intended for use with legacy drivers
 *	which probe hardware directly.  Because such drivers create sysfs
 *	device nodes themselves, rather than letting system infrastructure
 *	handle such device enumeration tasks, they don't fully conform to
 *	the Linux driver model.  In particular, when such drivers are built
 *	as modules, they can't be "hotplugged".
 */
struct platform_device *platform_device_register_simple(char *name, int id,
							struct resource *res, unsigned int num)
{
	struct platform_device *pdev;
	int retval;

	pdev = platform_device_alloc(name, id);
	if (!pdev) {
		retval = -ENOMEM;
		goto error;
	}

	if (num) {
		retval = platform_device_add_resources(pdev, res, num);
		if (retval)
			goto error;
	}

	retval = platform_device_add(pdev);
	if (retval)
		goto error;

	return pdev;

error:
	platform_device_put(pdev);
	return ERR_PTR(retval);
}
EXPORT_SYMBOL_GPL(platform_device_register_simple);

static int platform_drv_probe(struct device *_dev)
{
	struct platform_driver *drv = to_platform_driver(_dev->driver);
	struct platform_device *dev = to_platform_device(_dev);

	return drv->probe(dev);
}

static int platform_drv_probe_fail(struct device *_dev)
{
	return -ENXIO;
}

static int platform_drv_remove(struct device *_dev)
{
	struct platform_driver *drv = to_platform_driver(_dev->driver);
	struct platform_device *dev = to_platform_device(_dev);

	return drv->remove(dev);
}

static void platform_drv_shutdown(struct device *_dev)
{
	struct platform_driver *drv = to_platform_driver(_dev->driver);
	struct platform_device *dev = to_platform_device(_dev);

	drv->shutdown(dev);
}

static int platform_drv_suspend(struct device *_dev, pm_message_t state)
{
	struct platform_driver *drv = to_platform_driver(_dev->driver);
	struct platform_device *dev = to_platform_device(_dev);

	return drv->suspend(dev, state);
}

static int platform_drv_resume(struct device *_dev)
{
	struct platform_driver *drv = to_platform_driver(_dev->driver);
	struct platform_device *dev = to_platform_device(_dev);

	return drv->resume(dev);
}

/**
 *	platform_driver_register
 *	@drv: platform driver structure
 */
int platform_driver_register(struct platform_driver *drv)
{
	drv->driver.bus = &platform_bus_type;
	if (drv->probe)
		drv->driver.probe = platform_drv_probe;
	if (drv->remove)
		drv->driver.remove = platform_drv_remove;
	if (drv->shutdown)
		drv->driver.shutdown = platform_drv_shutdown;
	if (drv->suspend)
		drv->driver.suspend = platform_drv_suspend;
	if (drv->resume)
		drv->driver.resume = platform_drv_resume;
	return driver_register(&drv->driver);
}
EXPORT_SYMBOL_GPL(platform_driver_register);

/**
 *	platform_driver_unregister
 *	@drv: platform driver structure
 */
void platform_driver_unregister(struct platform_driver *drv)
{
	driver_unregister(&drv->driver);
}
EXPORT_SYMBOL_GPL(platform_driver_unregister);

/**
 * platform_driver_probe - register driver for non-hotpluggable device
 * @drv: platform driver structure
 * @probe: the driver probe routine, probably from an __init section
 *
 * Use this instead of platform_driver_register() when you know the device
 * is not hotpluggable and has already been registered, and you want to
 * remove its run-once probe() infrastructure from memory after the driver
 * has bound to the device.
 *
 * One typical use for this would be with drivers for controllers integrated
 * into system-on-chip processors, where the controller devices have been
 * configured as part of board setup.
 *
 * Returns zero if the driver registered and bound to a device, else returns
 * a negative error code and with the driver not registered.
 */
int __init_or_module platform_driver_probe(struct platform_driver *drv,
		int (*probe)(struct platform_device *))
{
	int retval, code;

	/* temporary section violation during probe() */
	drv->probe = probe;
	retval = code = platform_driver_register(drv);

	/* Fixup that section violation, being paranoid about code scanning
	 * the list of drivers in order to probe new devices.  Check to see
	 * if the probe was successful, and make sure any forced probes of
	 * new devices fail.
	 */
	spin_lock(&platform_bus_type.klist_drivers.k_lock);
	drv->probe = NULL;
	if (code == 0 && list_empty(&drv->driver.klist_devices.k_list))
		retval = -ENODEV;
	drv->driver.probe = platform_drv_probe_fail;
	spin_unlock(&platform_bus_type.klist_drivers.k_lock);

	if (code != retval)
		platform_driver_unregister(drv);
	return retval;
}
EXPORT_SYMBOL_GPL(platform_driver_probe);

/* modalias support enables more hands-off userspace setup:
 * (a) environment variable lets new-style hotplug events work once system is
 *     fully running:  "modprobe $MODALIAS"
 * (b) sysfs attribute lets new-style coldplug recover from hotplug events
 *     mishandled before system is fully running:  "modprobe $(cat modalias)"
 */
static ssize_t
modalias_show(struct device *dev, struct device_attribute *a, char *buf)
{
	struct platform_device	*pdev = to_platform_device(dev);
	int len = snprintf(buf, PAGE_SIZE, "platform:%s\n", pdev->name);

	return (len >= PAGE_SIZE) ? (PAGE_SIZE - 1) : len;
}

static struct device_attribute platform_dev_attrs[] = {
	__ATTR_RO(modalias),
	__ATTR_NULL,
};

static int platform_uevent(struct device *dev, struct kobj_uevent_env *env)
{
	struct platform_device	*pdev = to_platform_device(dev);

	add_uevent_var(env, "MODALIAS=platform:%s", pdev->name);
	return 0;
}


/**
 *	platform_match - bind platform device to platform driver.
 *	@dev:	device.
 *	@drv:	driver.
 *
 *	Platform device IDs are assumed to be encoded like this:
 *	"<name><instance>", where <name> is a short description of the
 *	type of device, like "pci" or "floppy", and <instance> is the
 *	enumerated instance of the device, like '0' or '42'.
 *	Driver IDs are simply "<name>".
 *	So, extract the <name> from the platform_device structure,
 *	and compare it against the name of the driver. Return whether
 *	they match or not.
 */

static int platform_match(struct device * dev, struct device_driver * drv)
{
	struct platform_device *pdev = container_of(dev, struct platform_device, dev);

	return (strncmp(pdev->name, drv->name, BUS_ID_SIZE) == 0);
}

static int platform_suspend(struct device *dev, pm_message_t mesg)
{
	int ret = 0;

	if (dev->driver && dev->driver->suspend)
		ret = dev->driver->suspend(dev, mesg);

	return ret;
}

static int platform_suspend_late(struct device *dev, pm_message_t mesg)
{
	struct platform_driver *drv = to_platform_driver(dev->driver);
	struct platform_device *pdev = container_of(dev, struct platform_device, dev);
	int ret = 0;

	if (dev->driver && drv->suspend_late)
		ret = drv->suspend_late(pdev, mesg);

	return ret;
}

static int platform_resume_early(struct device *dev)
{
	struct platform_driver *drv = to_platform_driver(dev->driver);
	struct platform_device *pdev = container_of(dev, struct platform_device, dev);
	int ret = 0;

	if (dev->driver && drv->resume_early)
		ret = drv->resume_early(pdev);

	return ret;
}

static int platform_resume(struct device * dev)
{
	int ret = 0;

	if (dev->driver && dev->driver->resume)
		ret = dev->driver->resume(dev);

	return ret;
}

struct bus_type platform_bus_type = {
	.name		= "platform",
	.dev_attrs	= platform_dev_attrs,
	.match		= platform_match,
	.uevent		= platform_uevent,
	.suspend	= platform_suspend,
	.suspend_late	= platform_suspend_late,
	.resume_early	= platform_resume_early,
	.resume		= platform_resume,
};
EXPORT_SYMBOL_GPL(platform_bus_type);

int __init platform_bus_init(void)
{
	int error;

	error = device_register(&platform_bus);
	if (error)
		return error;
	error =  bus_register(&platform_bus_type);
	if (error)
		device_unregister(&platform_bus);
	return error;
}

#ifndef ARCH_HAS_DMA_GET_REQUIRED_MASK
u64 dma_get_required_mask(struct device *dev)
{
	u32 low_totalram = ((max_pfn - 1) << PAGE_SHIFT);
	u32 high_totalram = ((max_pfn - 1) >> (32 - PAGE_SHIFT));
	u64 mask;

	if (!high_totalram) {
		/* convert to mask just covering totalram */
		low_totalram = (1 << (fls(low_totalram) - 1));
		low_totalram += low_totalram - 1;
		mask = low_totalram;
	} else {
		high_totalram = (1 << (fls(high_totalram) - 1));
		high_totalram += high_totalram - 1;
		mask = (((u64)high_totalram) << 32) + 0xffffffff;
	}
	return mask & *dev->dma_mask;
}
EXPORT_SYMBOL_GPL(dma_get_required_mask);
#endif