ACPI / scan: Add support for ACPI _CLS device matching
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. Also, certain classes of devices
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.
To support loadable module, current design uses _HID or _CID to match device's
modalias. With the new way of matching with _CLS this would requires modification
to the current ACPI modalias key to include _CLS. This patch appends PCI-defined
class-code to the existing ACPI modalias as following.
acpi:<HID>:<CID1>:<CID2>:..:<CIDn>:<bbsspp>:
E.g:
# cat /sys/devices/platform/AMDI0600:00/modalias
acpi:AMDI0600:010601:
where bb is th base-class code, ss is te sub-class code, and pp is the
programming interface code
Since there would not be _HID/_CID in the ACPI matching table of the driver,
this patch adds a field to acpi_device_id to specify the matching _CLS.
static const struct acpi_device_id ahci_acpi_match[] = {
{ ACPI_DEVICE_CLASS(PCI_CLASS_STORAGE_SATA_AHCI, 0xffffff) },
{},
};
In this case, the corresponded entry in modules.alias file would be:
alias acpi*:010601:* ahci_platform
Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Reviewed-by: Hanjun Guo <hanjun.guo@linaro.org>
Signed-off-by: Suravee Suthikulpanit <Suravee.Suthikulpanit@amd.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index 2649a06..ec25635 100644
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -1019,6 +1019,29 @@
return false;
}
+static bool __acpi_match_device_cls(const struct acpi_device_id *id,
+ struct acpi_hardware_id *hwid)
+{
+ int i, msk, byte_shift;
+ char buf[3];
+
+ if (!id->cls)
+ return false;
+
+ /* Apply class-code bitmask, before checking each class-code byte */
+ for (i = 1; i <= 3; i++) {
+ byte_shift = 8 * (3 - i);
+ msk = (id->cls_msk >> byte_shift) & 0xFF;
+ if (!msk)
+ continue;
+
+ sprintf(buf, "%02x", (id->cls >> byte_shift) & msk);
+ if (strncmp(buf, &hwid->id[(i - 1) * 2], 2))
+ return false;
+ }
+ return true;
+}
+
static const struct acpi_device_id *__acpi_match_device(
struct acpi_device *device,
const struct acpi_device_id *ids,
@@ -1036,9 +1059,12 @@
list_for_each_entry(hwid, &device->pnp.ids, list) {
/* First, check the ACPI/PNP IDs provided by the caller. */
- for (id = ids; id->id[0]; id++)
- if (!strcmp((char *) id->id, hwid->id))
+ for (id = ids; id->id[0] || id->cls; id++) {
+ if (id->id[0] && !strcmp((char *) id->id, hwid->id))
return id;
+ else if (id->cls && __acpi_match_device_cls(id, hwid))
+ return id;
+ }
/*
* Next, check ACPI_DT_NAMESPACE_HID and try to match the
@@ -2101,6 +2127,8 @@
if (info->valid & ACPI_VALID_UID)
pnp->unique_id = kstrdup(info->unique_id.string,
GFP_KERNEL);
+ if (info->valid & ACPI_VALID_CLS)
+ acpi_add_id(pnp, info->class_code.string);
kfree(info);