[RFC PATCH v2 03/16] ACPI: Allow drivers to match using Device Tree compatible property

[Mika Westerberg]

We have lots of existing Device Tree enabled drivers and allocating
separate _HID for each is not feasible. Instead we allocate special _HID
"PRP0001" that means that the match should be done using Device Tree
compatible property using driver's .of_match_table instead.

If there is a need to distinguish from where the device is enumerated
(DT/ACPI) driver can check dev->of_node or ACPI_COMPATION(dev).

Signed-off-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>
---
 drivers/acpi/property.c | 34 ++++++++++++++++++
 drivers/acpi/scan.c     | 91 +++++++++++++++++++++++++++++++++++++++++++------
 include/acpi/acpi_bus.h |  1 +
 include/linux/acpi.h    |  8 ++---
 4 files changed, 118 insertions(+), 16 deletions(-)

diff --git a/drivers/acpi/property.c b/drivers/acpi/property.c
index e50964012da8..c6c3ab6f68c3 100644
--- a/drivers/acpi/property.c
+++ b/drivers/acpi/property.c
@@ -76,6 +76,37 @@ static bool acpi_properties_format_valid(const union acpi_object *properties)
 	return true;
 }
 
+static void acpi_init_of_compatible(struct acpi_device *adev)
+{
+	const union acpi_object *of_compatible;
+	struct acpi_hardware_id *hwid;
+	bool acpi_of = false;
+
+	/*
+	 * Check if the special PRP0001 ACPI ID is present and in that
+	 * case we fill in Device Tree compatible properties for this
+	 * device.
+	 */
+	list_for_each_entry(hwid, &adev->pnp.ids, list) {
+		if (!strcmp(hwid->id, "PRP0001")) {
+			acpi_of = true;
+			break;
+		}
+	}
+
+	if (!acpi_of)
+		return;
+
+	if (acpi_dev_get_property_array(adev, "compatible", ACPI_TYPE_STRING,
+					&of_compatible)) {
+		acpi_handle_warn(adev->handle,
+				 "PRP0001 requires compatible property\n");
+		return;
+	}
+
+	adev->data.of_compatible = of_compatible;
+}
+
 void acpi_init_properties(struct acpi_device *adev)
 {
 	struct acpi_buffer buf = { ACPI_ALLOCATE_BUFFER };
@@ -119,6 +150,8 @@ void acpi_init_properties(struct acpi_device *adev)
 
 		adev->data.pointer = buf.pointer;
 		adev->data.properties = properties;
+
+		acpi_init_of_compatible(adev);
 		return;
 	}
 
@@ -130,6 +163,7 @@ void acpi_init_properties(struct acpi_device *adev)
 void acpi_free_properties(struct acpi_device *adev)
 {
 	ACPI_FREE((void *)adev->data.pointer);
+	adev->data.of_compatible = NULL;
 	adev->data.pointer = NULL;
 	adev->data.properties = NULL;
 }
diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index f4aabf9c0aad..0c8e751cbe6b 100644
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -124,17 +124,43 @@ static int create_modalias(struct acpi_device *acpi_dev, char *modalias,
 	if (list_empty(&acpi_dev->pnp.ids))
 		return 0;
 
-	len = snprintf(modalias, size, "acpi:");
-	size -= len;
+	/*
+	 * If the device has PRP0001 we expose DT compatible modalias
+	 * instead.
+	 */
+	if (acpi_dev->data.of_compatible) {
+		const union acpi_object *of_compatible, *obj;
+		int i;
+
+		len = snprintf(modalias, size, "of:Nprp0001Tacpi");
+
+		of_compatible = acpi_dev->data.of_compatible;
+		for (i = 0; i < of_compatible->package.count; i++) {
+			obj = &of_compatible->package.elements[i];
 
-	list_for_each_entry(id, &acpi_dev->pnp.ids, list) {
-		count = snprintf(&modalias[len], size, "%s:", id->id);
-		if (count < 0)
-			return -EINVAL;
-		if (count >= size)
-			return -ENOMEM;
-		len += count;
-		size -= count;
+			count = snprintf(&modalias[len], size, "C%s",
+					 obj->string.pointer);
+			if (count < 0)
+				return -EINVAL;
+			if (count >= size)
+				return -ENOMEM;
+
+			len += count;
+			size -= count;
+		}
+	} else {
+		len = snprintf(modalias, size, "acpi:");
+		size -= len;
+
+		list_for_each_entry(id, &acpi_dev->pnp.ids, list) {
+			count = snprintf(&modalias[len], size, "%s:", id->id);
+			if (count < 0)
+				return -EINVAL;
+			if (count >= size)
+				return -ENOMEM;
+			len += count;
+			size -= count;
+		}
 	}
 
 	modalias[len] = '\0';
@@ -864,6 +890,51 @@ int acpi_match_device_ids(struct acpi_device *device,
 }
 EXPORT_SYMBOL(acpi_match_device_ids);
 
+/* Performs match for special "PRP0001" shoehorn ACPI ID */
+static bool acpi_of_driver_match_device(struct device *dev,
+					const struct device_driver *drv)
+{
+	struct acpi_device *adev = ACPI_COMPANION(dev);
+	const union acpi_object *of_compatible;
+	int i;
+
+	/*
+	 * If the ACPI device does not have corresponding compatible
+	 * property or the driver in question does not have DT matching
+	 * table we consider the match succesful (matches the ACPI ID).
+	 */
+	of_compatible = adev->data.of_compatible;
+	if (!drv->of_match_table || !of_compatible)
+		return true;
+
+	/* Now we can look for the driver DT compatible strings */
+	for (i = 0; i < of_compatible->package.count; i++) {
+		const struct of_device_id *id;
+		const union acpi_object *obj;
+
+		obj = &of_compatible->package.elements[i];
+
+		for (id = drv->of_match_table; id->compatible[0]; id++)
+			if (!strcasecmp(obj->string.pointer, id->compatible))
+				return true;
+	}
+
+	return false;
+}
+
+bool acpi_driver_match_device(struct device *dev,
+			      const struct device_driver *drv)
+{
+	const struct acpi_device_id *id;
+
+	id = acpi_match_device(drv->acpi_match_table, dev);
+	if (!id)
+		return false;
+
+	return acpi_of_driver_match_device(dev, drv);
+}
+EXPORT_SYMBOL_GPL(acpi_driver_match_device);
+
 static void acpi_free_power_resources_lists(struct acpi_device *device)
 {
 	int i;
diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h
index 620b4f89c87b..65866e23e3e9 100644
--- a/include/acpi/acpi_bus.h
+++ b/include/acpi/acpi_bus.h
@@ -341,6 +341,7 @@ struct acpi_device_physical_node {
 struct acpi_device_data {
 	const union acpi_object *pointer;
 	const union acpi_object *properties;
+	const union acpi_object *of_compatible;
 };
 
 /* Device */
diff --git a/include/linux/acpi.h b/include/linux/acpi.h
index 288abbdf2fb4..37a5280a64a5 100644
--- a/include/linux/acpi.h
+++ b/include/linux/acpi.h
@@ -424,12 +424,8 @@ extern int acpi_nvs_for_each_region(int (*func)(__u64, __u64, void *),
 const struct acpi_device_id *acpi_match_device(const struct acpi_device_id *ids,
 					       const struct device *dev);
 
-static inline bool acpi_driver_match_device(struct device *dev,
-					    const struct device_driver *drv)
-{
-	return !!acpi_match_device(drv->acpi_match_table, dev);
-}
-
+extern bool acpi_driver_match_device(struct device *dev,
+				     const struct device_driver *drv);
 int acpi_device_uevent_modalias(struct device *, struct kobj_uevent_env *);
 int acpi_device_modalias(struct device *, char *, int);
 
-- 
2.1.0

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