Vfio-platform requires dedicated 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. If the reset hierarchy is described in DT using "resets" properties, or in lookup tables in platform code, such devices can be reset in a generic way through the reset controller subsystem. Hence add support for this, avoiding the need to write device-specific reset drivers for each single device on affected SoCs. Devices that do 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 (as in: "No reset function found for device") if reset controller support is disabled. Signed-off-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx> Reviewed-by: Philipp Zabel <p.zabel@xxxxxxxxxxxxxx> Reviewed-by: Simon Horman <horms+renesas@xxxxxxxxxxxx> --- v4: - Add Reviewed-by, - Use new RFC reset_control_get_dedicated() instead of of_reset_control_get_exclusive(), to (a) make it more generic, and (b) make sure the reset returned is really a dedicated reset, and does not affect other devices, v3: - Add Reviewed-by, - Merge similar checks in vfio_platform_has_reset(), v2: - Don't store error values in vdev->reset_control, - Use of_reset_control_get_exclusive() instead of __of_reset_control_get(), - Improve description. --- drivers/vfio/platform/vfio_platform_common.c | 20 +++++++++++++++++-- drivers/vfio/platform/vfio_platform_private.h | 1 + 2 files changed, 19 insertions(+), 2 deletions(-) diff --git a/drivers/vfio/platform/vfio_platform_common.c b/drivers/vfio/platform/vfio_platform_common.c index c0cd824be2b767be..eb77fe87f3663e3e 100644 --- a/drivers/vfio/platform/vfio_platform_common.c +++ b/drivers/vfio/platform/vfio_platform_common.c @@ -18,6 +18,7 @@ #include <linux/module.h> #include <linux/mutex.h> #include <linux/pm_runtime.h> +#include <linux/reset.h> #include <linux/slab.h> #include <linux/types.h> #include <linux/uaccess.h> @@ -113,11 +114,13 @@ 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; + return vdev->of_reset || vdev->reset_control; } static int vfio_platform_get_reset(struct vfio_platform_device *vdev) { + struct reset_control *rstc; + if (VFIO_PLATFORM_IS_ACPI(vdev)) return vfio_platform_acpi_has_reset(vdev) ? 0 : -ENOENT; @@ -128,8 +131,16 @@ 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; + + rstc = reset_control_get_dedicated(vdev->device, NULL); + if (!IS_ERR(rstc)) { + vdev->reset_control = rstc; + return 0; + } - return vdev->of_reset ? 0 : -ENOENT; + return PTR_ERR(rstc); } static void vfio_platform_put_reset(struct vfio_platform_device *vdev) @@ -139,6 +150,8 @@ 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) @@ -218,6 +231,9 @@ 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 (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; /* -- 2.17.1