ARM: 8256/1: driver coamba: add device binding path 'driver_override' (3cf38571) · Commits · 戴 / test

Documentation/ABI/testing/sysfs-bus-amba

0 → 100644

+20 −0

Original line number	Diff line number	Diff line
		What: /sys/bus/amba/devices/.../driver_override
		Date: September 2014
		Contact: Antonios Motakis <a.motakis@virtualopensystems.com>
		Description:
		This file allows the driver for a device to be specified which
		will override standard OF, ACPI, ID table, and name matching.
		When specified, only a driver with a name matching the value
		written to driver_override will have an opportunity to bind to
		the device. The override is specified by writing a string to the
		driver_override file (echo vfio-amba > driver_override) and may
		be cleared with an empty string (echo > driver_override).
		This returns the device to standard matching rules binding.
		Writing to driver_override does not automatically unbind the
		device from its current driver or make any attempt to
		automatically load the specified driver. If no driver with a
		matching name is currently loaded in the kernel, the device will
		not bind to any driver. This also allows devices to opt-out of
		driver binding using a driver_override name such as "none".
		Only a single driver may be specified in the override, there is
		no support for parsing delimiters.

drivers/amba/bus.c

+47 −0

Original line number	Diff line number	Diff line
		@@ -18,6 +18,7 @@
		#include <linux/pm_domain.h>
		#include <linux/amba/bus.h>
		#include <linux/sizes.h>
		#include <linux/limits.h>

		#include <asm/irq.h>

		@@ -43,6 +44,10 @@ static int amba_match(struct device dev, struct device_driver drv)
		struct amba_device *pcdev = to_amba_device(dev);
		struct amba_driver *pcdrv = to_amba_driver(drv);

		/* When driver_override is set, only bind to the matching driver */
		if (pcdev->driver_override)
		return !strcmp(pcdev->driver_override, drv->name);

		return amba_lookup(pcdrv->id_table, pcdev) != NULL;
		}

		@@ -59,6 +64,47 @@ static int amba_uevent(struct device dev, struct kobj_uevent_env env)
		return retval;
		}

		static ssize_t driver_override_show(struct device *_dev,
		struct device_attribute attr, char buf)
		{
		struct amba_device *dev = to_amba_device(_dev);

		if (!dev->driver_override)
		return 0;

		return sprintf(buf, "%s\n", dev->driver_override);
		}

		static ssize_t driver_override_store(struct device *_dev,
		struct device_attribute *attr,
		const char *buf, size_t count)
		{
		struct amba_device *dev = to_amba_device(_dev);
		char driver_override, old = dev->driver_override, *cp;

		if (count > PATH_MAX)
		return -EINVAL;

		driver_override = kstrndup(buf, count, GFP_KERNEL);
		if (!driver_override)
		return -ENOMEM;

		cp = strchr(driver_override, '\n');
		if (cp)
		*cp = '\0';

		if (strlen(driver_override)) {
		dev->driver_override = driver_override;
		} else {
		kfree(driver_override);
		dev->driver_override = NULL;
		}

		kfree(old);

		return count;
		}

		#define amba_attr_func(name,fmt,arg...) \
		static ssize_t name##_show(struct device *_dev, \
		struct device_attribute attr, char buf) \
		@@ -81,6 +127,7 @@ amba_attr_func(resource, "\t%016llx\t%016llx\t%016lx\n",
		static struct device_attribute amba_dev_attrs[] = {
		__ATTR_RO(id),
		__ATTR_RO(resource),
		__ATTR_RW(driver_override),
		__ATTR_NULL,
		};

include/linux/amba/bus.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -33,6 +33,7 @@ struct amba_device {
		struct clk *pclk;
		unsigned int periphid;
		unsigned int irq[AMBA_NR_IRQS];
		char *driver_override;
		};

		struct amba_driver {

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