Re: [PATCH 1/2] vfio, platform: add support for ACPI while detecting the reset driver

Eric Auger
2016-03-10T10:13:34Z

Hi Sinan,
On 03/08/2016 04:33 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.
> The change allows a driver to register with DT compatible string or ACPI
> HID and then match the object with one of these conditions.
>
> Rules for loading the reset driver are as follow:
> - ACPI HID needs match for ACPI systems
> - DT compat needs to match for OF systems
>
> Tested-by: Eric Auger <eric.auger@linaro.org> (device tree only)
> Tested-by: Shanker Donthineni <shankerd@codeaurora.org> (ACPI only)
> Signed-off-by: Sinan Kaya <okaya@codeaurora.org>
> ---
> .../vfio/platform/reset/vfio_platform_amdxgbe.c | 4 +-
> .../platform/reset/vfio_platform_calxedaxgmac.c | 4 +-
> drivers/vfio/platform/vfio_platform_common.c | 112 +++++++++++++++++----
> drivers/vfio/platform/vfio_platform_private.h | 43 ++++----
> 4 files changed, 125 insertions(+), 38 deletions(-)
>
> diff --git a/drivers/vfio/platform/reset/vfio_platform_amdxgbe.c b/drivers/vfio/platform/reset/vfio_platform_amdxgbe.c
> index d4030d0..170dcf5 100644
> --- a/drivers/vfio/platform/reset/vfio_platform_amdxgbe.c
> +++ b/drivers/vfio/platform/reset/vfio_platform_amdxgbe.c
> @@ -119,7 +119,9 @@ int vfio_platform_amdxgbe_reset(struct vfio_platform_device *vdev)
> return 0;
> }
>
> -module_vfio_reset_handler("amd,xgbe-seattle-v1a", vfio_platform_amdxgbe_reset);
> +module_vfio_reset_handler("amd,xgbe-seattle-v1a", NULL,
> + vfio_platform_amdxgbe_reset);
> +VFIO_PLATFORM_MODULE_ALIAS("amd,xgbe-seattle-v1a");
Looks the other overridden MODULE_ALIAS have a naming like
MODULE_ALIAS_something? what about MODULE_ALIAS_VFIO_PLATFORM_RESET?
not very compact but maybe closer to what it stands for.
>
> MODULE_VERSION("0.1");
> MODULE_LICENSE("GPL v2");
> diff --git a/drivers/vfio/platform/reset/vfio_platform_calxedaxgmac.c b/drivers/vfio/platform/reset/vfio_platform_calxedaxgmac.c
> index e3d3d94..635c6e0 100644
> --- a/drivers/vfio/platform/reset/vfio_platform_calxedaxgmac.c
> +++ b/drivers/vfio/platform/reset/vfio_platform_calxedaxgmac.c
> @@ -77,7 +77,9 @@ int vfio_platform_calxedaxgmac_reset(struct vfio_platform_device *vdev)
> return 0;
> }
>
> -module_vfio_reset_handler("calxeda,hb-xgmac", vfio_platform_calxedaxgmac_reset);
> +module_vfio_reset_handler("calxeda,hb-xgmac", NULL,
> + vfio_platform_calxedaxgmac_reset);
> +VFIO_PLATFORM_MODULE_ALIAS("calxeda,hb-xgmac");
>
> MODULE_VERSION(DRIVER_VERSION);
> MODULE_LICENSE("GPL v2");
> diff --git a/drivers/vfio/platform/vfio_platform_common.c b/drivers/vfio/platform/vfio_platform_common.c
> index 418cdd9..c758e72 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>
> @@ -31,14 +32,22 @@ static LIST_HEAD(reset_list);
> static DEFINE_MUTEX(driver_lock);
>
> static vfio_platform_reset_fn_t vfio_platform_lookup_reset(const char *compat,
> - struct module **module)
> + const char *acpihid, struct module **module)
> {
> struct vfio_platform_reset_node *iter;
> vfio_platform_reset_fn_t reset_fn = NULL;
>
> mutex_lock(&driver_lock);
> list_for_each_entry(iter, &reset_list, link) {
> - if (!strcmp(iter->compat, compat) &&
> + if (acpihid && iter->acpihid &&
> + !strcmp(iter->acpihid, acpihid) &&
> + try_module_get(iter->owner)) {
> + *module = iter->owner;
> + reset_fn = iter->reset;
> + break;
> + }
> + if (compat && iter->compat &&
> + !strcmp(iter->compat, compat) &&
> try_module_get(iter->owner)) {
> *module = iter->owner;
> reset_fn = iter->reset;
> @@ -49,15 +58,30 @@ 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)
> +static int vfio_platform_get_reset(struct vfio_platform_device *vdev)
What is the point returning a value here? See my comment at the end.
> {
> - 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);
> - }
> + int rc = 0;
> +
> + vdev->reset = vfio_platform_lookup_reset(vdev->compat, vdev->acpihid,
> + &vdev->reset_module);
> + if (vdev->reset)
> + return 0;
> +
> + if (vdev->acpihid)
> + rc = request_module("vfio-reset:%s", vdev->acpihid);
> +
> + if (rc && vdev->compat)
> + rc = request_module("vfio-reset:%s", vdev->compat);
> +
> + if (rc)
> + return rc;
> +
> + vdev->reset = vfio_platform_lookup_reset(vdev->compat, vdev->acpihid,
> + &vdev->reset_module);
> + if (vdev->reset)
> + return 0;
> +
> + return -ENODEV;
> }
>
> static void vfio_platform_put_reset(struct vfio_platform_device *vdev)
> @@ -541,6 +565,46 @@ static const struct vfio_device_ops vfio_platform_ops = {
> .mmap = vfio_platform_mmap,
> };
>
> +#ifdef CONFIG_ACPI
> +int vfio_platform_probe_acpi(struct vfio_platform_device *vdev,
> + struct device *dev)
> +{
> + struct acpi_device* adev = ACPI_COMPANION(dev);
checkpatch reports: ERROR: "foo* bar" should be "foo *bar"
> +
> + 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;
> +}
> +#else
> +int vfio_platform_probe_acpi(struct vfio_platform_device *vdev,
> + struct device *dev)
> +{
> + return -EINVAL;
> +}
> +#endif
> +
> +int vfio_platform_probe_of(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)
> {
> @@ -550,14 +614,14 @@ 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_probe_acpi(vdev, dev);
> + if (ret)
> + ret = vfio_platform_probe_of(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);
> @@ -570,7 +634,11 @@ int vfio_platform_probe_common(struct vfio_platform_device *vdev,
> return ret;
> }
>
> - vfio_platform_get_reset(vdev);
> + ret = vfio_platform_get_reset(vdev);
> + if (ret) {
> + iommu_group_put(group);
> + return ret;
> + }
This change is not related to your commit message. Also here you change
the use model of VFIO platform and forbid any usage if no reset module
is available, right? I don't think this is something we discussed and I
think it removes some flexibility. Currently a warning is emitted in
case we don't have a reset function.

Best Regards

Eric
>
> mutex_init(&vdev->igate);
>
> @@ -602,13 +670,21 @@ void __vfio_platform_register_reset(struct vfio_platform_reset_node *node)
> EXPORT_SYMBOL_GPL(__vfio_platform_register_reset);
>
> void vfio_platform_unregister_reset(const char *compat,
> + const char *acpihid,
> vfio_platform_reset_fn_t fn)
> {
> struct vfio_platform_reset_node *iter, *temp;
>
> mutex_lock(&driver_lock);
> list_for_each_entry_safe(iter, temp, &reset_list, link) {
> - if (!strcmp(iter->compat, compat) && (iter->reset == fn)) {
> + if (acpihid && iter->acpihid &&
> + !strcmp(iter->acpihid, acpihid) && (iter->reset == fn)) {
> + list_del(&iter->link);
> + break;
> + }
> +
> + if (compat && iter->compat &&
> + !strcmp(iter->compat, compat) && (iter->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..20787f7 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;
>
> @@ -79,6 +80,7 @@ typedef int (*vfio_platform_reset_fn_t)(struct vfio_platform_device *vdev);
> struct vfio_platform_reset_node {
> struct list_head link;
> char *compat;
> + char *acpihid;
> struct module *owner;
> vfio_platform_reset_fn_t reset;
> };
> @@ -98,27 +100,32 @@ extern int vfio_platform_set_irqs_ioctl(struct vfio_platform_device *vdev,
>
> extern void __vfio_platform_register_reset(struct vfio_platform_reset_node *n);
> extern void vfio_platform_unregister_reset(const char *compat,
> + const char *acpihid,
> vfio_platform_reset_fn_t fn);
> -#define vfio_platform_register_reset(__compat, __reset) \
> -static struct vfio_platform_reset_node __reset ## _node = { \
> - .owner = THIS_MODULE, \
> - .compat = __compat, \
> - .reset = __reset, \
> -}; \
> +
> +#define vfio_platform_register_reset(__compat, __acpihid, __reset) \
> +static struct vfio_platform_reset_node __reset ## _node = { \
> + .owner = THIS_MODULE, \
> + .compat = __compat, \
> + .acpihid = __acpihid, \
> + .reset = __reset, \
> +}; \
> __vfio_platform_register_reset(&__reset ## _node)
>
> -#define module_vfio_reset_handler(compat, reset) \
> -MODULE_ALIAS("vfio-reset:" compat); \
> -static int __init reset ## _module_init(void) \
> -{ \
> - vfio_platform_register_reset(compat, reset); \
> - return 0; \
> -}; \
> -static void __exit reset ## _module_exit(void) \
> -{ \
> - vfio_platform_unregister_reset(compat, reset); \
> -}; \
> -module_init(reset ## _module_init); \
> +#define VFIO_PLATFORM_MODULE_ALIAS(name) \
> + MODULE_ALIAS("vfio-reset:" name)
> +
> +#define module_vfio_reset_handler(compat, acpihid, reset) \
> +static int __init reset ## _module_init(void) \
> +{ \
> + vfio_platform_register_reset(compat, acpihid, reset); \
> + return 0; \
> +}; \
> +static void __exit reset ## _module_exit(void) \
> +{ \
> + vfio_platform_unregister_reset(compat, acpihid, reset); \
> +}; \
> +module_init(reset ## _module_init); \
> module_exit(reset ## _module_exit)
>
> #endif /* VFIO_PLATFORM_PRIVATE_H */
>