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@xxxxxxxxxxxxxxxxxxxxxx> --- drivers/amba/bus.c | 44 ++++++++++++++++++++++++++++++++++++++++++++ include/linux/amba/bus.h | 1 + 2 files changed, 45 insertions(+) diff --git a/drivers/amba/bus.c b/drivers/amba/bus.c index 3cf61a1..473177c 100644 --- a/drivers/amba/bus.c +++ b/drivers/amba/bus.c @@ -17,6 +17,7 @@ #include <linux/pm_runtime.h> #include <linux/amba/bus.h> #include <linux/sizes.h> +#include <linux/limits.h> #include <asm/irq.h> @@ -42,6 +43,10 @@ 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; } @@ -58,6 +63,44 @@ 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); + + 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) \ @@ -80,6 +123,7 @@ 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, }; diff --git a/include/linux/amba/bus.h b/include/linux/amba/bus.h index fdd7e1b..7c011e7 100644 --- a/include/linux/amba/bus.h +++ b/include/linux/amba/bus.h @@ -32,6 +32,7 @@ struct amba_device { struct clk *pclk; unsigned int periphid; unsigned int irq[AMBA_NR_IRQS]; + char *driver_override; }; struct amba_driver { -- 1.8.3.2 -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
