[PATCH V4 1/2] vfio, platform: add support for ACPI during probe and reset

Eric Auger
2016-05-09T15:47:06Z

Hi Sinan,
On 05/01/2016 11:07 PM, Sinan Kaya 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.
>
> When ACPI is enabled, the change will query the presence of _RST method
> and will call it instead of querying an external reset driver.
>
> Signed-off-by: Sinan Kaya <okaya@codeaurora.org>
> ---
> drivers/vfio/platform/vfio_platform_common.c | 176 +++++++++++++++++++++-----
> drivers/vfio/platform/vfio_platform_private.h | 7 +-
> 2 files changed, 147 insertions(+), 36 deletions(-)
>
> diff --git a/drivers/vfio/platform/vfio_platform_common.c b/drivers/vfio/platform/vfio_platform_common.c
> index e65b142..528ec04 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>
> @@ -41,7 +42,7 @@ static vfio_platform_reset_fn_t vfio_platform_lookup_reset(const char *compat,
> if (!strcmp(iter->compat, compat) &&
> try_module_get(iter->owner)) {
> *module = iter->owner;
> - reset_fn = iter->reset;
> + reset_fn = iter->of_reset;
> break;
> }
> }
> @@ -49,20 +50,111 @@ static vfio_platform_reset_fn_t vfio_platform_lookup_reset(const char *compat,
> return reset_fn;
> }
>
> -static void vfio_platform_get_reset(struct vfio_platform_device *vdev)
> +
> +#ifdef CONFIG_ACPI
> +int vfio_platform_acpi_probe(struct vfio_platform_device *vdev,
> + struct device *dev)
> {
> - vdev->reset = vfio_platform_lookup_reset(vdev->compat,
> - &vdev->reset_module);
> - if (!vdev->reset) {
> - request_module("vfio-reset:%s", vdev->compat);
> - vdev->reset = vfio_platform_lookup_reset(vdev->compat,
> - &vdev->reset_module);
> + struct acpi_device *adev = ACPI_COMPANION(dev);
> +
> + if (acpi_disabled)
> + return -ENODEV;
> +
> + if (!adev)
> + 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;
> }
> + return 0;
> +}
> +
> +static int vfio_platform_acpi_call_reset(struct vfio_platform_device *vdev)
> +{
> + struct device *dev = vdev->device;
> + acpi_handle handle = ACPI_HANDLE(dev);
> + acpi_status acpi_ret;
> + unsigned long long val;
> +
> + acpi_ret = acpi_evaluate_integer(handle, "_RST", NULL, &val);
> + if (ACPI_FAILURE(acpi_ret))
> + return -EINVAL;
> +
> + return 0;
> +}
> +
> +static int vfio_platform_acpi_has_reset(struct vfio_platform_device *vdev)
> +{
> + struct device *dev = vdev->device;
> + acpi_handle handle = ACPI_HANDLE(dev);
> +
> + if (acpi_has_method(handle, "_RST"))
> + return 0;
Can't you directly return acpi_has_method(handle, "_RST"), hence return
a boolean?
> +
> + return -EINVAL;
> +}
> +#else
> +int vfio_platform_acpi_probe(struct vfio_platform_device *vdev,
> + struct device *dev)
> +{
> + return -EINVAL;
> +}
> +
> +static int vfio_platform_acpi_call_reset(struct vfio_platform_device *vdev)
> +{
> + return -EINVAL;
> +}
> +
> +static int vfio_platform_acpi_has_reset(struct vfio_platform_device *vdev)
> +{
> + return -EINVAL;
> +}
> +#endif
> +
> +static int vfio_platform_has_reset(struct vfio_platform_device *vdev)
> +{
return a boolean?
> + if (vdev->acpihid)
> + return vfio_platform_acpi_has_reset(vdev);
> +
> + if (vdev->of_reset)
> + return 0;
> +
> + return -EINVAL;
> +}
> +
> +static int vfio_platform_get_reset(struct vfio_platform_device *vdev)
> +{
> + int rc;
> +
> + if (vdev->acpihid)
> + return vfio_platform_acpi_has_reset(vdev);
> +
> + vdev->of_reset = vfio_platform_lookup_reset(vdev->compat,
> + &vdev->reset_module);
> + if (vdev->of_reset)
> + return 0;
> +
> + rc = request_module("vfio-reset:%s", vdev->compat);
> + if (rc)
> + return rc;
> +
> + vdev->of_reset = vfio_platform_lookup_reset(vdev->compat,
> + &vdev->reset_module);
> + if (vdev->of_reset)
> + return 0;
> +
> + return -EINVAL;
> }
>
> static void vfio_platform_put_reset(struct vfio_platform_device *vdev)
> {
> - if (vdev->reset)
> + if (vdev->acpihid)
> + return;
> +
> + if (vdev->of_reset)
> module_put(vdev->reset_module);
> }
>
> @@ -134,6 +226,20 @@ static void vfio_platform_regions_cleanup(struct vfio_platform_device *vdev)
> kfree(vdev->regions);
> }
>
> +static int vfio_platform_call_reset(struct vfio_platform_device *vdev)
> +{
> + if (vdev->of_reset) {
> + dev_info(vdev->device, "reset\n");
> + vdev->of_reset(vdev);
return vdev->of_reset(vdev) to align with acpi reset behavior.
> + return 0;
> + } else if (vdev->acpihid) {
> + return vfio_platform_acpi_call_reset(vdev);
I think it would make sense to have the same dev_info traces for dt and
acpi.
> + }
> +
> + dev_warn(vdev->device, "no reset function found!\n");
> + return -EINVAL;
> +}
> +
> static void vfio_platform_release(void *device_data)
> {
> struct vfio_platform_device *vdev = device_data;
> @@ -141,12 +247,7 @@ static void vfio_platform_release(void *device_data)
> mutex_lock(&driver_lock);
>
> if (!(--vdev->refcnt)) {
> - if (vdev->reset) {
> - dev_info(vdev->device, "reset\n");
> - vdev->reset(vdev);
> - } else {
> - dev_warn(vdev->device, "no reset function found!\n");
> - }
> + vfio_platform_call_reset(vdev);
> vfio_platform_regions_cleanup(vdev);
> vfio_platform_irq_cleanup(vdev);
> }
> @@ -175,12 +276,9 @@ static int vfio_platform_open(void *device_data)
> if (ret)
> goto err_irq;
>
> - if (vdev->reset) {
> - dev_info(vdev->device, "reset\n");
> - vdev->reset(vdev);
> - } else {
> - dev_warn(vdev->device, "no reset function found!\n");
> - }
> + ret = vfio_platform_call_reset(vdev);
> + if (ret)
> + goto err_irq;
This change should be in next patch since if you fail finding a reset
function, you clean things up, mandating a reset function to exist.

Also in case the reset function fails you change the behavior which is
not detailed in the commit msg.
> }
>
> vdev->refcnt++;
> @@ -213,7 +311,7 @@ static long vfio_platform_ioctl(void *device_data,
> if (info.argsz < minsz)
> return -EINVAL;
>
> - if (vdev->reset)
> + if (!vfio_platform_has_reset(vdev))
> vdev->flags |= VFIO_DEVICE_FLAGS_RESET;
> info.flags = vdev->flags;
> info.num_regions = vdev->num_regions;
> @@ -312,10 +410,7 @@ static long vfio_platform_ioctl(void *device_data,
> return ret;
>
> } else if (cmd == VFIO_DEVICE_RESET) {
> - if (vdev->reset)
> - return vdev->reset(vdev);
> - else
> - return -EINVAL;
> + return vfio_platform_call_reset(vdev);
Here you also change the behavior: before, in case the dt reset failed
we returned an error. Now we return 0.

To me this patch would deserve to be split into 2 parts: ACPI probing
without reset and then ACPI reset. In case you change the behavior of
existing dt reset, please put that in a separate patch.

Best Regards

Eric
> }
>
> return -ENOTTY;
> @@ -544,6 +639,21 @@ 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);
> + return ret;
> + }
> + return 0;
> +}
> +
> int vfio_platform_probe_common(struct vfio_platform_device *vdev,
> struct device *dev)
> {
> @@ -553,14 +663,14 @@ 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);
>
> - vdev->device = dev;
> + if (ret)
> + return ret;
>
> + vdev->device = dev;
> group = iommu_group_get(dev);
> if (!group) {
> pr_err("VFIO: No IOMMU group for device %s\n", vdev->name);
> @@ -611,7 +721,7 @@ void vfio_platform_unregister_reset(const char *compat,
>
> mutex_lock(&driver_lock);
> list_for_each_entry_safe(iter, temp, &reset_list, link) {
> - if (!strcmp(iter->compat, compat) && (iter->reset == fn)) {
> + if (!strcmp(iter->compat, compat) && (iter->of_reset == fn)) {
> list_del(&iter->link);
> break;
> }
> diff --git a/drivers/vfio/platform/vfio_platform_private.h b/drivers/vfio/platform/vfio_platform_private.h
> index 42816dd..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;
>
> @@ -71,7 +72,7 @@ struct vfio_platform_device {
> struct resource*
> (*get_resource)(struct vfio_platform_device *vdev, int i);
> int (*get_irq)(struct vfio_platform_device *vdev, int i);
> - int (*reset)(struct vfio_platform_device *vdev);
> + int (*of_reset)(struct vfio_platform_device *vdev);
> };
>
> typedef int (*vfio_platform_reset_fn_t)(struct vfio_platform_device *vdev);
> @@ -80,7 +81,7 @@ struct vfio_platform_reset_node {
> struct list_head link;
> char *compat;
> struct module *owner;
> - vfio_platform_reset_fn_t reset;
> + vfio_platform_reset_fn_t of_reset;
> };
>
> extern int vfio_platform_probe_common(struct vfio_platform_device *vdev,
> @@ -103,7 +104,7 @@ extern void vfio_platform_unregister_reset(const char *compat,
> static struct vfio_platform_reset_node __reset ## _node = { \
> .owner = THIS_MODULE, \
> .compat = __compat, \
> - .reset = __reset, \
> + .of_reset = __reset, \
> }; \
> __vfio_platform_register_reset(&__reset ## _node)
>
>