Re: [PATCH V14 8/9] vfio, platform: add support for ACPI while detecting the reset driver

[Eric Auger]

Hi Sinan,
On 02/05/2016 05:34 AM, 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@xxxxxxxxxx> (device tree only)
> Tested-by: Shanker Donthineni <shankerd@xxxxxxxxxxxxxx> (ACPI only)
> Signed-off-by: Sinan Kaya <okaya@xxxxxxxxxxxxxx>
> ---
>  .../vfio/platform/reset/vfio_platform_amdxgbe.c    |  3 +-
>  .../platform/reset/vfio_platform_calxedaxgmac.c    |  3 +-
>  drivers/vfio/platform/vfio_platform_common.c       | 80 +++++++++++++++++++---
>  drivers/vfio/platform/vfio_platform_private.h      | 41 ++++++-----
>  4 files changed, 96 insertions(+), 31 deletions(-)
> 
> diff --git a/drivers/vfio/platform/reset/vfio_platform_amdxgbe.c b/drivers/vfio/platform/reset/vfio_platform_amdxgbe.c
> index d4030d0..cc5b4fa 100644
> --- a/drivers/vfio/platform/reset/vfio_platform_amdxgbe.c
> +++ b/drivers/vfio/platform/reset/vfio_platform_amdxgbe.c
> @@ -119,7 +119,8 @@ 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);
>  
>  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..0e57529 100644
> --- a/drivers/vfio/platform/reset/vfio_platform_calxedaxgmac.c
> +++ b/drivers/vfio/platform/reset/vfio_platform_calxedaxgmac.c
> @@ -77,7 +77,8 @@ 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);
>  
>  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..5b42e93 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;
> @@ -51,11 +60,12 @@ static vfio_platform_reset_fn_t vfio_platform_lookup_reset(const char *compat,
>  
>  static void vfio_platform_get_reset(struct vfio_platform_device *vdev)
>  {
> -	vdev->reset = vfio_platform_lookup_reset(vdev->compat,
> -						&vdev->reset_module);
> +	vdev->reset = vfio_platform_lookup_reset(vdev->compat, vdev->acpihid,
> +						 &vdev->reset_module);
>  	if (!vdev->reset) {
>  		request_module("vfio-reset:%s", vdev->compat);
>  		vdev->reset = vfio_platform_lookup_reset(vdev->compat,
> +							 vdev->acpihid,
>  							 &vdev->reset_module);
>  	}
>  }
> @@ -541,6 +551,46 @@ 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);
> +
> +	if (!adev)
> +		return -EINVAL;
-ENODEV seems to be commonly used in that case
> +
> +	vdev->acpihid = acpi_device_hid(adev);
> +	if (!vdev->acpihid) {
can it return NULL? Seems to return dummy "device" or actual hid
> +		pr_err("VFIO: cannot find ACPI HID for %s\n",
> +		       vdev->name);
> +		return -EINVAL;
-ENODEV too?
> +	}
> +	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 -EINVAL;
return ret instead.
> +	}
> +	return 0;
> +}
> +
>  int vfio_platform_probe_common(struct vfio_platform_device *vdev,
>  			       struct device *dev)
>  {
> @@ -550,14 +600,14 @@ 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);
> @@ -602,13 +652,21 @@ 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;
>  		}

in vfio_platform_get_reset, if the 1st vfio_platform_lookup_reset call
does not return anything then we currently call
request_module("vfio-reset:%s", vdev->compat);

you need to handle the case where compat is not set but vdev->acpihid
is, instead.

currently the module alias is constructed with the compat only
MODULE_ALIAS("vfio-reset:" compat);

Looks you can define several ones ( for instance in
drivers/block/xen-blkfront.c).

If I am not wrong this currently would not work with
vfio-platform-qcomhidma compiled as a module.





> diff --git a/drivers/vfio/platform/vfio_platform_private.h b/drivers/vfio/platform/vfio_platform_private.h
> index 42816dd..32feba3 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 +100,30 @@ 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 module_vfio_reset_handler(compat, acpihid, reset)		\
> +MODULE_ALIAS("vfio-reset:" compat);					\
Here you need to handle alias for hid case I think

Best Regards

Eric
> +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 */
>