On Mon, 20 Jun 2016 11:51:14 -0400
Sinan Kaya <okaya@xxxxxxxxxxxxxx> wrote:
> The code is using the compatible DT string to associate a reset driver
> with the actual device itself. The compatible string does not exist on
> ACPI based systems. HID is the unique identifier for a device driver
> instead.
>
> Signed-off-by: Sinan Kaya <okaya@xxxxxxxxxxxxxx>
> Reviewed-by: Eric Auger <eric.auger@xxxxxxxxxx>
> Reviewed-by: Baptiste Reynal <b.reynal@xxxxxxxxxxxxxxxxxxxxxx>
> ---
> drivers/vfio/platform/vfio_platform_common.c | 57 ++++++++++++++++++++++++---
> drivers/vfio/platform/vfio_platform_private.h | 1 +
> 2 files changed, 53 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/vfio/platform/vfio_platform_common.c b/drivers/vfio/platform/vfio_platform_common.c
> index 6be92c3..fbf4565 100644
> --- a/drivers/vfio/platform/vfio_platform_common.c
> +++ b/drivers/vfio/platform/vfio_platform_common.c
> @@ -13,6 +13,7 @@
> */
>
> #include <linux/device.h>
> +#include <linux/acpi.h>
> #include <linux/iommu.h>
> #include <linux/module.h>
> #include <linux/mutex.h>
> @@ -49,6 +50,37 @@ static vfio_platform_reset_fn_t vfio_platform_lookup_reset(const char *compat,
> return reset_fn;
> }
>
> +#ifdef CONFIG_ACPI
> +static int vfio_platform_acpi_probe(struct vfio_platform_device *vdev,
> + struct device *dev)
> +{
> + struct acpi_device *adev = ACPI_COMPANION(dev);
> +
> + if (acpi_disabled)
> + return -ENODEV;
> +
> + if (!adev) {
> + pr_err("VFIO: ACPI companion device not found for %s\n",
> + vdev->name);
> + return -ENODEV;
> + }
> +
> + vdev->acpihid = acpi_device_hid(adev);
> + if (!vdev->acpihid) {
> + pr_err("VFIO: cannot find ACPI HID for %s\n",
> + vdev->name);
> + return -ENODEV;
> + }
Do you want to try to use different errnos here so you don't rely on
the pr_err() calls for debugging? I could imagine -EPERM, -ENODEV,
-EINVAL respectively, but maybe there are better options.
> + return 0;
> +}
> +#else
> +static inline int vfio_platform_acpi_probe(struct vfio_platform_device *vdev,
> + struct device *dev)
> +{
> + return -ENOENT;
> +}
> +#endif
> +
> static bool vfio_platform_has_reset(struct vfio_platform_device *vdev)
> {
> return vdev->of_reset ? true : false;
> @@ -547,6 +579,20 @@ static const struct vfio_device_ops vfio_platform_ops = {
> .mmap = vfio_platform_mmap,
> };
>
> +int vfio_platform_of_probe(struct vfio_platform_device *vdev,
> + struct device *dev)
> +{
> + int ret;
> +
> + ret = device_property_read_string(dev, "compatible",
> + &vdev->compat);
> + if (ret)
> + pr_err("VFIO: cannot retrieve compat for %s\n",
> + vdev->name);
Previously there was only one probe method and I imagine this pr_err
was useful. Now we have multiple methods of probing for the device.
Do we really want each one generating pr_err messages or just one at
the end if none of our probes worked?
> +
> + return ret;
> +}
> +
> int vfio_platform_probe_common(struct vfio_platform_device *vdev,
> struct device *dev)
> {
> @@ -556,11 +602,12 @@ int vfio_platform_probe_common(struct vfio_platform_device *vdev,
> if (!vdev)
> return -EINVAL;
>
> - ret = device_property_read_string(dev, "compatible", &vdev->compat);
> - if (ret) {
> - pr_err("VFIO: cannot retrieve compat for %s\n", vdev->name);
> - return -EINVAL;
> - }
> + ret = vfio_platform_acpi_probe(vdev, dev);
> + if (ret)
> + ret = vfio_platform_of_probe(vdev, dev);
The only out way out of vfio_platform_acpi_probe() without hitting a
pr_err is one of (!CONFIG_ACPI || acpi_disabled || success). Doesn't
that make for some unnecessary warning for a DT user?
> +
> + if (ret)
> + return ret;
>
> vdev->device = dev;
>
> diff --git a/drivers/vfio/platform/vfio_platform_private.h b/drivers/vfio/platform/vfio_platform_private.h
> index 71ed7d1..ba9e4f8 100644
> --- a/drivers/vfio/platform/vfio_platform_private.h
> +++ b/drivers/vfio/platform/vfio_platform_private.h
> @@ -58,6 +58,7 @@ struct vfio_platform_device {
> struct mutex igate;
> struct module *parent_module;
> const char *compat;
> + const char *acpihid;
> struct module *reset_module;
> struct device *device;
>
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