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Subject[V3 PATCH 1/2] ACPI / scan: Add support for ACPI _CLS device matching
Date
Device drivers typically use ACPI _HIDs/_CIDs listed in struct device_driver
acpi_match_table to match devices. However, for generic drivers, we do
not want to list _HID for all supported devices, and some device classes
do not have _CID (e.g. SATA, USB). Instead, we can leverage ACPI _CLS,
which specifies PCI-defined class code (i.e. base-class, subclass and
programming interface).

This patch adds support for matching ACPI devices using the _CLS method.

Signed-off-by: Suravee Suthikulpanit <Suravee.Suthikulpanit@amd.com>
---
drivers/acpi/scan.c | 75 +++++++++++++++++++++++++++++++++++++++--
include/acpi/acnames.h | 1 +
include/linux/acpi.h | 10 ++++++
include/linux/device.h | 1 +
include/linux/mod_devicetable.h | 6 ++++
5 files changed, 90 insertions(+), 3 deletions(-)

diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index dc4d896..0579395 100644
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -987,13 +987,82 @@ static bool acpi_of_driver_match_device(struct device *dev,
bool acpi_driver_match_device(struct device *dev,
const struct device_driver *drv)
{
- if (!drv->acpi_match_table)
- return acpi_of_driver_match_device(dev, drv);
+ bool ret = false;

- return !!acpi_match_device(drv->acpi_match_table, dev);
+ if (drv->acpi_match_table)
+ ret = !!acpi_match_device(drv->acpi_match_table, dev);
+
+ /* Next, try to match with special "PRP0001" _HID */
+ if (!ret && drv->of_match_table)
+ ret = acpi_of_driver_match_device(dev, drv);
+
+ /* Next, try to match with PCI-defined class-code */
+ if (!ret && drv->acpi_match_cls)
+ ret = acpi_match_device_cls(drv->acpi_match_cls, dev);
+
+ return ret;
}
EXPORT_SYMBOL_GPL(acpi_driver_match_device);

+/**
+ * acpi_match_device_cls - Match a struct device against a ACPI _CLS method
+ * @dev_cls: A pointer to struct acpi_device_cls object to match against.
+ * @dev: The ACPI device structure to match.
+ *
+ * Check if @dev has a valid ACPI and _CLS handle. If there is a
+ * struct acpi_device_cls object for that handle, use that object to match
+ * against the given struct acpi_device_cls object.
+ *
+ * Return true on success or false on failure.
+ */
+bool acpi_match_device_cls(const struct acpi_device_cls *dev_cls,
+ const struct device *dev)
+{
+ acpi_status status;
+ union acpi_object *pkg;
+ struct acpi_device_cls cls;
+ struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
+ struct acpi_buffer format = { sizeof("NNN"), "NNN" };
+ struct acpi_buffer state = { 0, NULL };
+ struct acpi_device *adev = ACPI_COMPANION(dev);
+
+ if (!adev || !adev->status.present || !dev_cls)
+ return false;
+
+ status = acpi_evaluate_object(adev->handle, METHOD_NAME__CLS,
+ NULL, &buffer);
+ if (ACPI_FAILURE(status))
+ return false;
+
+ /**
+ * Note:
+ * ACPIv5.1 defines the package to contain 3 integers for
+ * Base-Class code, Sub-Class code, and Programming Interface code.
+ */
+ pkg = buffer.pointer;
+ if (!pkg ||
+ (pkg->type != ACPI_TYPE_PACKAGE) ||
+ (pkg->package.count != 3)) {
+ dev_dbg(&adev->dev, "Invalid _CLS data\n");
+ goto out;
+ }
+
+ state.length = sizeof(struct acpi_device_cls);
+ state.pointer = &cls;
+
+ status = acpi_extract_package(pkg, &format, &state);
+ if (ACPI_FAILURE(status))
+ goto out;
+
+ return (dev_cls->base_class == cls.base_class &&
+ dev_cls->sub_class == cls.sub_class &&
+ dev_cls->prog_interface == cls.prog_interface);
+out:
+ kfree(pkg);
+ return false;
+}
+EXPORT_SYMBOL_GPL(acpi_match_device_cls);
+
static void acpi_free_power_resources_lists(struct acpi_device *device)
{
int i;
diff --git a/include/acpi/acnames.h b/include/acpi/acnames.h
index 7461327..22332a6 100644
--- a/include/acpi/acnames.h
+++ b/include/acpi/acnames.h
@@ -51,6 +51,7 @@
#define METHOD_NAME__BBN "_BBN"
#define METHOD_NAME__CBA "_CBA"
#define METHOD_NAME__CID "_CID"
+#define METHOD_NAME__CLS "_CLS"
#define METHOD_NAME__CRS "_CRS"
#define METHOD_NAME__DDN "_DDN"
#define METHOD_NAME__HID "_HID"
diff --git a/include/linux/acpi.h b/include/linux/acpi.h
index 536991b..9a01d5d 100644
--- a/include/linux/acpi.h
+++ b/include/linux/acpi.h
@@ -442,6 +442,10 @@ const struct acpi_device_id *acpi_match_device(const struct acpi_device_id *ids,

extern bool acpi_driver_match_device(struct device *dev,
const struct device_driver *drv);
+
+bool acpi_match_device_cls(const struct acpi_device_cls *dev_cls,
+ const struct device *dev);
+
int acpi_device_uevent_modalias(struct device *, struct kobj_uevent_env *);
int acpi_device_modalias(struct device *, char *, int);
void acpi_walk_dep_device_list(acpi_handle handle);
@@ -542,6 +546,12 @@ static inline const struct acpi_device_id *acpi_match_device(
return NULL;
}

+static inline bool acpi_match_device_cls(const struct acpi_device_cls *dev_cls,
+ const struct device *dev)
+{
+ return false;
+}
+
static inline bool acpi_driver_match_device(struct device *dev,
const struct device_driver *drv)
{
diff --git a/include/linux/device.h b/include/linux/device.h
index fb50673..8e259c5c 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -237,6 +237,7 @@ struct device_driver {

const struct of_device_id *of_match_table;
const struct acpi_device_id *acpi_match_table;
+ const struct acpi_device_cls *acpi_match_cls;

int (*probe) (struct device *dev);
int (*remove) (struct device *dev);
diff --git a/include/linux/mod_devicetable.h b/include/linux/mod_devicetable.h
index 745def8..cf0e0d198 100644
--- a/include/linux/mod_devicetable.h
+++ b/include/linux/mod_devicetable.h
@@ -191,6 +191,12 @@ struct acpi_device_id {
kernel_ulong_t driver_data;
};

+struct acpi_device_cls {
+ kernel_ulong_t base_class;
+ kernel_ulong_t sub_class;
+ kernel_ulong_t prog_interface;
+};
+
#define PNP_ID_LEN 8
#define PNP_MAX_DEVICES 8

--
2.1.0


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