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.au...@linaro.org> (device tree only)
Tested-by: Shanker Donthineni <shank...@codeaurora.org> (ACPI only)
Signed-off-by: Sinan Kaya <ok...@codeaurora.org>
---
 .../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;
+
+       vdev->acpihid = acpi_device_hid(adev);
+       if (!vdev->acpihid) {
+               pr_err("VFIO: cannot find ACPI HID for %s\n",
+                      vdev->name);
+               return -EINVAL;
+       }
+       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 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;
                }
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);                                    \
+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 */
-- 
1.8.2.1

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