Hi Geert,
I have a suggestion to avoid having to use the IS_ERR_OR_NULL macro, see
below:
On Tue, 2018-02-13 at 17:36 +0100, Geert Uytterhoeven wrote:
> Vfio-platform requires reset support, provided either by ACPI, or, on DT
> platforms, by a device-specific reset driver matching against the
> device's compatible value.
>
> On many SoCs, devices are connected to an SoC-internal reset controller,
> and can be reset in a generic way. Hence add support to reset such
> devices using the reset controller subsystem, provided the reset
> hierarchy is described correctly in DT using the "resets" property.
>
> Devices that require a more complex reset procedure can still
> provide a device-specific reset driver, as that takes precedence.
>
> Note that this functionality depends on CONFIG_RESET_CONTROLLER=y, and
> becomes a no-op if reset controller support is disabled.
>
> Signed-off-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
> ---
> drivers/vfio/platform/vfio_platform_common.c | 23 +++++++++++++++++++++--
> drivers/vfio/platform/vfio_platform_private.h | 1 +
> 2 files changed, 22 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/vfio/platform/vfio_platform_common.c b/drivers/vfio/platform/vfio_platform_common.c
> index b60bb5326668498c..5d1e48f96e423508 100644
> --- a/drivers/vfio/platform/vfio_platform_common.c
> +++ b/drivers/vfio/platform/vfio_platform_common.c
> @@ -17,6 +17,7 @@
> #include <linux/iommu.h>
> #include <linux/module.h>
> #include <linux/mutex.h>
> +#include <linux/reset.h>
> #include <linux/slab.h>
> #include <linux/types.h>
> #include <linux/uaccess.h>
> @@ -112,7 +113,13 @@ static bool vfio_platform_has_reset(struct vfio_platform_device *vdev)
> if (VFIO_PLATFORM_IS_ACPI(vdev))
> return vfio_platform_acpi_has_reset(vdev);
>
> - return vdev->of_reset ? true : false;
> + if (vdev->of_reset)
> + return true;
> +
> + if (!IS_ERR_OR_NULL(vdev->reset_control))
> + return true;
I'd avoid storing error values in vdev->reset_control at all, so this
could be:
if (vdev->reset_control)
return true;
> +
> + return false;
> }
>
> static int vfio_platform_get_reset(struct vfio_platform_device *vdev)
> @@ -127,8 +134,15 @@ static int vfio_platform_get_reset(struct vfio_platform_device *vdev)
> vdev->of_reset = vfio_platform_lookup_reset(vdev->compat,
> &vdev->reset_module);
> }
> + if (vdev->of_reset)
> + return 0;
> +
> + vdev->reset_control = __of_reset_control_get(vdev->device->of_node,
> + NULL, 0, false, false);
> + if (!IS_ERR(vdev->reset_control))
> + return 0;
if you assign to a local variable first here:
struct reset_control *rstc;
...
rstc = of_reset_control_get_exclusive(vdev->device->of_node, NULL);
if (!IS_ERR(rstc)) {
vdev->reset_control = rstc;
return 0;
}
Also, please don't use __of_reset_control_get directly.
>
> - return vdev->of_reset ? 0 : -ENOENT;
> + return PTR_ERR(vdev->reset_control);
return PTR_ERR(rstc);
> }
>
> static void vfio_platform_put_reset(struct vfio_platform_device *vdev)
> @@ -138,6 +152,8 @@ static void vfio_platform_put_reset(struct vfio_platform_device *vdev)
>
> if (vdev->of_reset)
> module_put(vdev->reset_module);
> +
> + reset_control_put(vdev->reset_control);
> }
>
> static int vfio_platform_regions_init(struct vfio_platform_device *vdev)
> @@ -217,6 +233,9 @@ static int vfio_platform_call_reset(struct vfio_platform_device *vdev,
> } else if (vdev->of_reset) {
> dev_info(vdev->device, "reset\n");
> return vdev->of_reset(vdev);
> + } else if (!IS_ERR_OR_NULL(vdev->reset_control)) {
> + dev_info(vdev->device, "reset\n");
> + return reset_control_reset(vdev->reset_control);
} else {
if (vdev->reset_control)
dev_info(vdev->device, "reset\n");
return reset_control_reset(vdev->reset_control);
> }
>
> dev_warn(vdev->device, "no reset function found!\n");
> diff --git a/drivers/vfio/platform/vfio_platform_private.h b/drivers/vfio/platform/vfio_platform_private.h
> index 85ffe5d9d1abd94e..a56e80ae5986540b 100644
> --- a/drivers/vfio/platform/vfio_platform_private.h
> +++ b/drivers/vfio/platform/vfio_platform_private.h
> @@ -60,6 +60,7 @@ struct vfio_platform_device {
> const char *compat;
> const char *acpihid;
> struct module *reset_module;
> + struct reset_control *reset_control;
> struct device *device;
>
> /*
regards
Philipp
