On Tue, 2014-09-23 at 16:46 +0200, Antonios Motakis wrote:
> 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.mota...@virtualopensystems.com>
> ---
> drivers/amba/bus.c | 44 ++++++++++++++++++++++++++++++++++++++++++++
> include/linux/amba/bus.h | 1 +
> 2 files changed, 45 insertions(+)
Why are 7 & 8 being dragged into this series? Combine them into a
single patch and post it separately.
>
> 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 {
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