diff options
| -rw-r--r-- | Documentation/ABI/testing/sysfs-bus-platform | 20 | ||||
| -rw-r--r-- | drivers/base/platform.c | 47 | ||||
| -rw-r--r-- | include/linux/platform_device.h | 1 |
3 files changed, 68 insertions, 0 deletions
diff --git a/Documentation/ABI/testing/sysfs-bus-platform b/Documentation/ABI/testing/sysfs-bus-platform new file mode 100644 index 000000000000..5172a6124b27 --- /dev/null +++ b/Documentation/ABI/testing/sysfs-bus-platform @@ -0,0 +1,20 @@ +What: /sys/bus/platform/devices/.../driver_override +Date: April 2014 +Contact: Kim Phillips <kim.phillips@freescale.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-platform > \ + 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. diff --git a/drivers/base/platform.c b/drivers/base/platform.c index c48c4acb9b87..148f66a1d49a 100644 --- a/drivers/base/platform.c +++ b/drivers/base/platform.c @@ -23,6 +23,7 @@ #include <linux/pm_runtime.h> #include <linux/idr.h> #include <linux/acpi.h> +#include <linux/limits.h> #include "base.h" #include "power/power.h" @@ -191,6 +192,7 @@ static void platform_device_release(struct device *dev) kfree(pa->pdev.dev.platform_data); kfree(pa->pdev.mfd_cell); kfree(pa->pdev.resource); + kfree(pa->pdev.driver_override); kfree(pa); } @@ -698,8 +700,49 @@ static ssize_t modalias_show(struct device *dev, struct device_attribute *a, } static DEVICE_ATTR_RO(modalias); +static ssize_t driver_override_store(struct device *dev, + struct device_attribute *attr, + const char *buf, size_t count) +{ + struct platform_device *pdev = to_platform_device(dev); + char *driver_override, *old = pdev->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)) { + pdev->driver_override = driver_override; + } else { + kfree(driver_override); + pdev->driver_override = NULL; + } + + kfree(old); + + return count; +} + +static ssize_t driver_override_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + struct platform_device *pdev = to_platform_device(dev); + + return sprintf(buf, "%s\n", pdev->driver_override); +} +static DEVICE_ATTR_RW(driver_override); + + static struct attribute *platform_dev_attrs[] = { &dev_attr_modalias.attr, + &dev_attr_driver_override.attr, NULL, }; ATTRIBUTE_GROUPS(platform_dev); @@ -755,6 +798,10 @@ static int platform_match(struct device *dev, struct device_driver *drv) struct platform_device *pdev = to_platform_device(dev); struct platform_driver *pdrv = to_platform_driver(drv); + /* When driver_override is set, only bind to the matching driver */ + if (pdev->driver_override) + return !strcmp(pdev->driver_override, drv->name); + /* Attempt an OF style match first */ if (of_driver_match_device(dev, drv)) return 1; diff --git a/include/linux/platform_device.h b/include/linux/platform_device.h index 16f6654082dd..153d303af7eb 100644 --- a/include/linux/platform_device.h +++ b/include/linux/platform_device.h @@ -28,6 +28,7 @@ struct platform_device { struct resource *resource; const struct platform_device_id *id_entry; + char *driver_override; /* Driver name to force a match */ /* MFD cell pointer */ struct mfd_cell *mfd_cell; |