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author | Antonios Motakis <a.motakis@virtualopensystems.com> | 2015-01-06 11:15:11 +0100 |
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committer | Russell King <rmk+kernel@arm.linux.org.uk> | 2015-02-10 10:23:15 +0000 |
commit | 3cf385713460eb2bb4cb7ceb8ed89833b00b594b (patch) | |
tree | b9c51c20e360b31aa2a567d3857b3039d6e08fdf /drivers/amba | |
parent | 8684014d71e259f62f7dc24a20324e232806b2ef (diff) | |
download | blackbird-op-linux-3cf385713460eb2bb4cb7ceb8ed89833b00b594b.tar.gz blackbird-op-linux-3cf385713460eb2bb4cb7ceb8ed89833b00b594b.zip |
ARM: 8256/1: driver coamba: add device binding path 'driver_override'
As already demonstrated with PCI [1] and the platform bus [2], a
driver_override property in sysfs can be used to bypass the id
matching of a device to a AMBA driver. This can be used by VFIO to
bind to any AMBA device requested by the user.
[1] http://lists-archives.com/linux-kernel/28030441-pci-introduce-new-device-binding-path-using-pci_dev-driver_override.html
[2] https://www.redhat.com/archives/libvir-list/2014-April/msg00382.html
Signed-off-by: Antonios Motakis <a.motakis@virtualopensystems.com>
Reviewed-by: Kim Phillips <kim.phillips@freescale.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'drivers/amba')
-rw-r--r-- | drivers/amba/bus.c | 47 |
1 files changed, 47 insertions, 0 deletions
diff --git a/drivers/amba/bus.c b/drivers/amba/bus.c index 52ddd9fbb55e..f0099360039e 100644 --- a/drivers/amba/bus.c +++ b/drivers/amba/bus.c @@ -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, }; |