[V4 PATCH 0/2] Introduce ACPI support for ahci_platform driver

[V4 PATCH 0/2] Introduce ACPI support for ahci_platform driver

[Suravee Suthikulpanit]

This patch series introduce ACPI support for AHCI platform driver.
Existing ACPI support for AHCI assumes the device controller is a PCI device.
Since there is no ACPI _CID for generic AHCI controller, the driver
could not use it for matching devices. Therefore, this patch introduces
a mechanism for drivers to match devices using ACPI _CLS method.
_CLS contains PCI-defined class-code.

This patch series also modifies ACPI modalias to add class-code to the
exisiting format, which currently only uses _HID and _CIDs. This is required
to support loadable modules w/ _CLS.

This patch series is rebased from and tested with:

    http://git.linaro.org/leg/acpi/acpi.git acpi-5.1-v9

This topic was discussed earlier here (as part of introducing support for
AMD Seattle SATA controller):

    http://marc.info/?l=linux-arm-kernel&m=141083492521584&w=2

Changes from V3 (https://lkml.org/lkml/2015/2/8/106)
	* Instead of introducing new structure acpi_device_cls, add cls into
	  the acpi_device_id, and modify the __acpi_match_device
	  to also match for cls. (per Mika suggestion.)
	* Add loadable module support, which requires changes in ACPI
	  modalias. (per Mika suggestion.)
	* Rebased and tested with acpi-5.1-v9

Changes from V2 (https://lkml.org/lkml/2015/1/5/662)
	* Update with review comment from Rafael in patch 1/2
	* Rebased and tested with acpi-5.1-v8

Changes from V1 (https://lkml.org/lkml/2014/12/19/345)
	* Rebased to 3.19.0-rc2
	* Change from acpi_cls in device_driver to acpi_match_cls (Hanjun comment)
	* Change the matching logic in acpi_driver_match_device() due to the new
	  special PRP0001 _HID.
	* Simplify the return type of acpi_match_device_cls() to boolean.

Changes from RFC (https://lkml.org/lkml/2014/12/17/446)
	* Remove #ifdef and make non-ACPI version of the acpi_match_device_cls
	  as inline. (per Arnd)
	* Simplify logic to retrieve and evaluate _CLS handle. (per Hanjun)

Suravee Suthikulpanit (2):
  ACPI / scan: Add support for ACPI _CLS device matching
  ata: ahci_platform: Add ACPI _CLS matching

 drivers/acpi/acpica/acutils.h     |  3 ++
 drivers/acpi/acpica/nsxfname.c    | 20 +++++++++--
 drivers/acpi/acpica/utids.c       | 71 +++++++++++++++++++++++++++++++++++++++
 drivers/acpi/scan.c               | 17 ++++++++--
 drivers/ata/Kconfig               |  2 +-
 drivers/ata/ahci_platform.c       |  9 +++++
 include/acpi/acnames.h            |  1 +
 include/acpi/actypes.h            |  4 ++-
 include/linux/mod_devicetable.h   |  1 +
 scripts/mod/devicetable-offsets.c |  1 +
 scripts/mod/file2alias.c          | 13 +++++--
 11 files changed, 133 insertions(+), 9 deletions(-)

-- 
2.1.0

[V4 PATCH 1/2] ACPI / scan: Add support for ACPI _CLS device matching

[Suravee Suthikulpanit]

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[] = {
        { "", 0, PCI_CLASS_STORAGE_SATA_AHCI },
        {},
    };

In this case, the corresponded entry in modules.alias file would be:

    alias acpi*:010601:* ahci_platform

Signed-off-by: Suravee Suthikulpanit <Suravee.Suthikulpanit@amd.com>
---
 drivers/acpi/acpica/acutils.h     |  3 ++
 drivers/acpi/acpica/nsxfname.c    | 20 +++++++++--
 drivers/acpi/acpica/utids.c       | 71 +++++++++++++++++++++++++++++++++++++++
 drivers/acpi/scan.c               | 17 ++++++++--
 include/acpi/acnames.h            |  1 +
 include/acpi/actypes.h            |  4 ++-
 include/linux/mod_devicetable.h   |  1 +
 scripts/mod/devicetable-offsets.c |  1 +
 scripts/mod/file2alias.c          | 13 +++++--
 9 files changed, 123 insertions(+), 8 deletions(-)

diff --git a/drivers/acpi/acpica/acutils.h b/drivers/acpi/acpica/acutils.h
index c2f03e8..2aef850 100644
--- a/drivers/acpi/acpica/acutils.h
+++ b/drivers/acpi/acpica/acutils.h
@@ -430,6 +430,9 @@ acpi_status
 acpi_ut_execute_CID(struct acpi_namespace_node *device_node,
 		    struct acpi_pnp_device_id_list ** return_cid_list);
 
+acpi_status
+acpi_ut_execute_CLS(struct acpi_namespace_node *device_node,
+		    struct acpi_pnp_device_id **return_id);
 /*
  * utlock - reader/writer locks
  */
diff --git a/drivers/acpi/acpica/nsxfname.c b/drivers/acpi/acpica/nsxfname.c
index d66c326..e64dc7f 100644
--- a/drivers/acpi/acpica/nsxfname.c
+++ b/drivers/acpi/acpica/nsxfname.c
@@ -276,11 +276,12 @@ acpi_get_object_info(acpi_handle handle,
 	struct acpi_pnp_device_id *hid = NULL;
 	struct acpi_pnp_device_id *uid = NULL;
 	struct acpi_pnp_device_id *sub = NULL;
+	struct acpi_pnp_device_id *cls = NULL;
 	char *next_id_string;
 	acpi_object_type type;
 	acpi_name name;
 	u8 param_count = 0;
-	u8 valid = 0;
+	u16 valid = 0;
 	u32 info_size;
 	u32 i;
 	acpi_status status;
@@ -320,7 +321,7 @@ acpi_get_object_info(acpi_handle handle,
 	if ((type == ACPI_TYPE_DEVICE) || (type == ACPI_TYPE_PROCESSOR)) {
 		/*
 		 * Get extra info for ACPI Device/Processor objects only:
-		 * Run the Device _HID, _UID, _SUB, and _CID methods.
+		 * Run the Device _HID, _UID, _SUB, _CID and _CLS methods.
 		 *
 		 * Note: none of these methods are required, so they may or may
 		 * not be present for this device. The Info->Valid bitfield is used
@@ -363,6 +364,14 @@ acpi_get_object_info(acpi_handle handle,
 			     sizeof(struct acpi_pnp_device_id_list));
 			valid |= ACPI_VALID_CID;
 		}
+
+		/* Execute the Device._CLS method */
+
+		status = acpi_ut_execute_CLS(node, &cls);
+		if (ACPI_SUCCESS(status)) {
+			info_size += cls->length;
+			valid |= ACPI_VALID_CLS;
+		}
 	}
 
 	/*
@@ -486,6 +495,11 @@ acpi_get_object_info(acpi_handle handle,
 		}
 	}
 
+	if (cls) {
+		next_id_string = acpi_ns_copy_device_id(&info->cls,
+							cls, next_id_string);
+	}
+
 	/* Copy the fixed-length data */
 
 	info->info_size = info_size;
@@ -510,6 +524,8 @@ cleanup:
 	if (cid_list) {
 		ACPI_FREE(cid_list);
 	}
+	if (cls)
+		ACPI_FREE(cls);
 	return (status);
 }
 
diff --git a/drivers/acpi/acpica/utids.c b/drivers/acpi/acpica/utids.c
index 27431cf..a64b5d1 100644
--- a/drivers/acpi/acpica/utids.c
+++ b/drivers/acpi/acpica/utids.c
@@ -416,3 +416,74 @@ cleanup:
 	acpi_ut_remove_reference(obj_desc);
 	return_ACPI_STATUS(status);
 }
+
+/*******************************************************************************
+ *
+ * FUNCTION:    acpi_ut_execute_CLS
+ *
+ * PARAMETERS:  device_node         - Node for the device
+ *              return_id           - Where the string UID is returned
+ *
+ * RETURN:      Status
+ *
+ * DESCRIPTION: Executes the _CLS control method that returns PCI-defined
+ *              class code of the device. The ACPI spec define _CLS as a
+ *              package with three integers. The returned string has format:
+ *
+ *                      "bbsspp"
+ *              where:
+ *                  bb = Base-class code
+ *                  ss = Sub-class code
+ *                  pp = Programming Interface code
+ *
+ ******************************************************************************/
+
+acpi_status
+acpi_ut_execute_CLS(struct acpi_namespace_node *device_node,
+		    struct acpi_pnp_device_id **return_id)
+{
+	struct acpi_pnp_device_id *cls;
+	union acpi_operand_object *obj_desc;
+	union acpi_operand_object **cls_objects;
+	acpi_status status;
+
+	ACPI_FUNCTION_TRACE(ut_execute_CLS);
+	status = acpi_ut_evaluate_object(device_node, METHOD_NAME__CLS,
+					 ACPI_BTYPE_PACKAGE, &obj_desc);
+	if (ACPI_FAILURE(status))
+		return_ACPI_STATUS(status);
+
+	cls_objects = obj_desc->package.elements;
+
+	if (obj_desc->common.type == ACPI_TYPE_PACKAGE &&
+	    obj_desc->package.count == 3 &&
+	    cls_objects[0]->common.type == ACPI_TYPE_INTEGER &&
+	    cls_objects[1]->common.type == ACPI_TYPE_INTEGER &&
+	    cls_objects[2]->common.type == ACPI_TYPE_INTEGER) {
+
+		/* Allocate a buffer for the CLS */
+		cls = ACPI_ALLOCATE_ZEROED(sizeof(struct acpi_pnp_device_id) +
+					 (acpi_size) 7);
+		if (!cls) {
+			status = AE_NO_MEMORY;
+			goto cleanup;
+		}
+
+		cls->string =
+		    ACPI_ADD_PTR(char, cls, sizeof(struct acpi_pnp_device_id));
+
+		sprintf(cls->string, "%02x%02x%02x",
+			(u8)ACPI_TO_INTEGER(cls_objects[0]->integer.value),
+			(u8)ACPI_TO_INTEGER(cls_objects[1]->integer.value),
+			(u8)ACPI_TO_INTEGER(cls_objects[2]->integer.value));
+		cls->length = 7;
+		*return_id = cls;
+	}
+
+cleanup:
+
+	/* On exit, we must delete the return object */
+
+	acpi_ut_remove_reference(obj_desc);
+	return_ACPI_STATUS(status);
+}
diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index bbca783..f6ecbd1 100644
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -907,10 +907,19 @@ static const struct acpi_device_id *__acpi_match_device(
 	if (!device->status.present)
 		return NULL;
 
-	for (id = ids; id->id[0]; id++)
-		list_for_each_entry(hwid, &device->pnp.ids, list)
-			if (!strcmp((char *) id->id, hwid->id))
+	for (id = ids; id->id[0] || id->cls; id++) {
+		list_for_each_entry(hwid, &device->pnp.ids, list) {
+			if (id->id[0] && !strcmp((char *) id->id, hwid->id)) {
 				return id;
+			} else if (id->cls) {
+				char buf[7];
+
+				sprintf(buf, "%06x", id->cls);
+				if (!strcmp(buf, hwid->id))
+					return id;
+			}
+		}
+	}
 
 	return NULL;
 }
@@ -1974,6 +1983,8 @@ static void acpi_set_pnp_ids(acpi_handle handle, struct acpi_device_pnp *pnp,
 		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->cls.string);
 
 		kfree(info);
 
diff --git a/include/acpi/acnames.h b/include/acpi/acnames.h
index 273de70..b52c0dc 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/acpi/actypes.h b/include/acpi/actypes.h
index b034f10..50d8019 100644
--- a/include/acpi/actypes.h
+++ b/include/acpi/actypes.h
@@ -1148,7 +1148,7 @@ struct acpi_device_info {
 	u32 name;		/* ACPI object Name */
 	acpi_object_type type;	/* ACPI object Type */
 	u8 param_count;		/* If a method, required parameter count */
-	u8 valid;		/* Indicates which optional fields are valid */
+	u16 valid;		/* Indicates which optional fields are valid */
 	u8 flags;		/* Miscellaneous info */
 	u8 highest_dstates[4];	/* _sx_d values: 0xFF indicates not valid */
 	u8 lowest_dstates[5];	/* _sx_w values: 0xFF indicates not valid */
@@ -1158,6 +1158,7 @@ struct acpi_device_info {
 	struct acpi_pnp_device_id unique_id;	/* _UID value */
 	struct acpi_pnp_device_id subsystem_id;	/* _SUB value */
 	struct acpi_pnp_device_id_list compatible_id_list;	/* _CID list <must be last> */
+	struct acpi_pnp_device_id cls;	/* _CLS value */
 };
 
 /* Values for Flags field above (acpi_get_object_info) */
@@ -1174,6 +1175,7 @@ struct acpi_device_info {
 #define ACPI_VALID_CID                  0x20
 #define ACPI_VALID_SXDS                 0x40
 #define ACPI_VALID_SXWS                 0x80
+#define ACPI_VALID_CLS                  0x100
 
 /* Flags for _STA return value (current_status above) */
 
diff --git a/include/linux/mod_devicetable.h b/include/linux/mod_devicetable.h
index e530533..9a42522 100644
--- a/include/linux/mod_devicetable.h
+++ b/include/linux/mod_devicetable.h
@@ -189,6 +189,7 @@ struct css_device_id {
 struct acpi_device_id {
 	__u8 id[ACPI_ID_LEN];
 	kernel_ulong_t driver_data;
+	__u32 cls;
 };
 
 #define PNP_ID_LEN	8
diff --git a/scripts/mod/devicetable-offsets.c b/scripts/mod/devicetable-offsets.c
index f282516..7f68268 100644
--- a/scripts/mod/devicetable-offsets.c
+++ b/scripts/mod/devicetable-offsets.c
@@ -63,6 +63,7 @@ int main(void)
 
 	DEVID(acpi_device_id);
 	DEVID_FIELD(acpi_device_id, id);
+	DEVID_FIELD(acpi_device_id, cls);
 
 	DEVID(pnp_device_id);
 	DEVID_FIELD(pnp_device_id, id);
diff --git a/scripts/mod/file2alias.c b/scripts/mod/file2alias.c
index e614ef6..ba5998c 100644
--- a/scripts/mod/file2alias.c
+++ b/scripts/mod/file2alias.c
@@ -511,12 +511,21 @@ static int do_serio_entry(const char *filename,
 }
 ADD_TO_DEVTABLE("serio", serio_device_id, do_serio_entry);
 
-/* looks like: "acpi:ACPI0003 or acpi:PNP0C0B" or "acpi:LNXVIDEO" */
+/* looks like: "acpi:ACPI0003" or "acpi:PNP0C0B"  or "acpi:LNXVIDEO" or
+ *             "acpi:bbsspp" (bb=base-class, ss=sub-class, pp=prog-if)
+ *
+ * NOTE: * Each driver should use one of the following : _HID, _CIDs or _CLS.
+ */
 static int do_acpi_entry(const char *filename,
 			void *symval, char *alias)
 {
 	DEF_FIELD_ADDR(symval, acpi_device_id, id);
-	sprintf(alias, "acpi*:%s:*", *id);
+	DEF_FIELD_ADDR(symval, acpi_device_id, cls);
+
+	if (id && strlen((const char *)*id))
+		sprintf(alias, "acpi*:%s:*", *id);
+	else if (cls)
+		sprintf(alias, "acpi*:%06x:*", *cls);
 	return 1;
 }
 ADD_TO_DEVTABLE("acpi", acpi_device_id, do_acpi_entry);
-- 
2.1.0

[V4 PATCH 2/2] ata: ahci_platform: Add ACPI _CLS matching

[Suravee Suthikulpanit]

This patch adds ACPI supports for AHCI platform driver, which uses _CLS
method to match the device.

The following is an example of ASL structure in DSDT for a SATA controller,
which contains _CLS package to be matched by the ahci_platform driver:

  Device (AHC0) // AHCI Controller
  {
    Name(_HID, "AMDI0600")
    Name (_CCA, 1)
    Name (_CLS, Package (3)
    {
      0x01, // Base Class: Mass Storage
      0x06, // Sub-Class: serial ATA
      0x01, // Interface: AHCI
    })
    Name (_CRS, ResourceTemplate ()
    {
      Memory32Fixed (ReadWrite, 0xE0300000, 0x00010000)
      Interrupt (ResourceConsumer, Level, ActiveHigh, Exclusive,,,) { 387 }
    })
  }

Also, since ATA driver should not require PCI support for ATA_ACPI,
this patch removes dependency in the driver/ata/Kconfig.

Signed-off-by: Suravee Suthikulpanit <Suravee.Suthikulpanit@amd.com>
---
 drivers/ata/Kconfig         | 2 +-
 drivers/ata/ahci_platform.c | 9 +++++++++
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/ata/Kconfig b/drivers/ata/Kconfig
index 5f60155..50305e3 100644
--- a/drivers/ata/Kconfig
+++ b/drivers/ata/Kconfig
@@ -48,7 +48,7 @@ config ATA_VERBOSE_ERROR
 
 config ATA_ACPI
 	bool "ATA ACPI Support"
-	depends on ACPI && PCI
+	depends on ACPI
 	default y
 	help
 	  This option adds support for ATA-related ACPI objects.
diff --git a/drivers/ata/ahci_platform.c b/drivers/ata/ahci_platform.c
index 78d6ae0..842cd13 100644
--- a/drivers/ata/ahci_platform.c
+++ b/drivers/ata/ahci_platform.c
@@ -20,6 +20,8 @@
 #include <linux/platform_device.h>
 #include <linux/libata.h>
 #include <linux/ahci_platform.h>
+#include <linux/acpi.h>
+#include <linux/pci_ids.h>
 #include "ahci.h"
 
 #define DRV_NAME "ahci"
@@ -78,12 +80,19 @@ static const struct of_device_id ahci_of_match[] = {
 };
 MODULE_DEVICE_TABLE(of, ahci_of_match);
 
+static const struct acpi_device_id ahci_acpi_match[] = {
+	{ "", 0, PCI_CLASS_STORAGE_SATA_AHCI },
+	{},
+};
+MODULE_DEVICE_TABLE(acpi, ahci_acpi_match);
+
 static struct platform_driver ahci_driver = {
 	.probe = ahci_probe,
 	.remove = ata_platform_remove_one,
 	.driver = {
 		.name = DRV_NAME,
 		.of_match_table = ahci_of_match,
+		.acpi_match_table = ahci_acpi_match,
 		.pm = &ahci_pm_ops,
 	},
 };
-- 
2.1.0

Re: [V4 PATCH 2/2] ata: ahci_platform: Add ACPI _CLS matching

[Tejun Heo]

On Mon, Mar 02, 2015 at 02:27:20AM -0600, Suravee Suthikulpanit wrote:
> This patch adds ACPI supports for AHCI platform driver, which uses _CLS
> method to match the device.
> 
> The following is an example of ASL structure in DSDT for a SATA controller,
> which contains _CLS package to be matched by the ahci_platform driver:
> 
>   Device (AHC0) // AHCI Controller
>   {
>     Name(_HID, "AMDI0600")
>     Name (_CCA, 1)
>     Name (_CLS, Package (3)
>     {
>       0x01, // Base Class: Mass Storage
>       0x06, // Sub-Class: serial ATA
>       0x01, // Interface: AHCI
>     })
>     Name (_CRS, ResourceTemplate ()
>     {
>       Memory32Fixed (ReadWrite, 0xE0300000, 0x00010000)
>       Interrupt (ResourceConsumer, Level, ActiveHigh, Exclusive,,,) { 387 }
>     })
>   }
> 
> Also, since ATA driver should not require PCI support for ATA_ACPI,
> this patch removes dependency in the driver/ata/Kconfig.
> 
> Signed-off-by: Suravee Suthikulpanit <Suravee.Suthikulpanit@amd.com>

Looks good to me from the libata side.

 Acked-by: Tejun Heo <tj@kernel.org>

Please let me now if this needs to go through libata.

Thanks.

-- 
tejun

Re: [V4 PATCH 2/2] ata: ahci_platform: Add ACPI _CLS matching

[Suthikulpanit, Suravee]

On 3/2/15, 10:41, "Tejun Heo" <tj@kernel.org> wrote:

>On Mon, Mar 02, 2015 at 02:27:20AM -0600, Suravee Suthikulpanit wrote:
>> This patch adds ACPI supports for AHCI platform driver, which uses _CLS
>> method to match the device.
>> 
>> The following is an example of ASL structure in DSDT for a SATA
>>controller,
>> which contains _CLS package to be matched by the ahci_platform driver:
>> 
>>   Device (AHC0) // AHCI Controller
>>   {
>>     Name(_HID, "AMDI0600")
>>     Name (_CCA, 1)
>>     Name (_CLS, Package (3)
>>     {
>>       0x01, // Base Class: Mass Storage
>>       0x06, // Sub-Class: serial ATA
>>       0x01, // Interface: AHCI
>>     })
>>     Name (_CRS, ResourceTemplate ()
>>     {
>>       Memory32Fixed (ReadWrite, 0xE0300000, 0x00010000)
>>       Interrupt (ResourceConsumer, Level, ActiveHigh, Exclusive,,,) {
>>387 }
>>     })
>>   }
>> 
>> Also, since ATA driver should not require PCI support for ATA_ACPI,
>> this patch removes dependency in the driver/ata/Kconfig.
>> 
>> Signed-off-by: Suravee Suthikulpanit <Suravee.Suthikulpanit@amd.com>
>
>Looks good to me from the libata side.
>
> Acked-by: Tejun Heo <tj@kernel.org>
>
>Please let me now if this needs to go through libata.
>
>Thanks.
>
>-- 
>tejun

Thank you. I will let you know one the whole series is ready.

Suravee

Re: [V4 PATCH 1/2] ACPI / scan: Add support for ACPI _CLS device matching

[Suravee Suthikulanit]

On 3/2/2015 2:27 AM, Suravee Suthikulpanit wrote:
> 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[] = {
>          { "", 0, PCI_CLASS_STORAGE_SATA_AHCI },
>          {},
>      };
>
> In this case, the corresponded entry in modules.alias file would be:
>
>      alias acpi*:010601:* ahci_platform
>
> Signed-off-by: Suravee Suthikulpanit<Suravee.Suthikulpanit@amd.com>
> ---
>   drivers/acpi/acpica/acutils.h     |  3 ++
>   drivers/acpi/acpica/nsxfname.c    | 20 +++++++++--
>   drivers/acpi/acpica/utids.c       | 71 +++++++++++++++++++++++++++++++++++++++
>   drivers/acpi/scan.c               | 17 ++++++++--
>   include/acpi/acnames.h            |  1 +
>   include/acpi/actypes.h            |  4 ++-
>   include/linux/mod_devicetable.h   |  1 +
>   scripts/mod/devicetable-offsets.c |  1 +
>   scripts/mod/file2alias.c          | 13 +++++--
>   9 files changed, 123 insertions(+), 8 deletions(-)
>
> [....]
 >
> diff --git a/include/acpi/actypes.h b/include/acpi/actypes.h
> index b034f10..50d8019 100644
> --- a/include/acpi/actypes.h
> +++ b/include/acpi/actypes.h
> @@ -1148,7 +1148,7 @@ struct acpi_device_info {
>   	u32 name;		/* ACPI object Name */
>   	acpi_object_type type;	/* ACPI object Type */
>   	u8 param_count;		/* If a method, required parameter count */
> -	u8 valid;		/* Indicates which optional fields are valid */
> +	u16 valid;		/* Indicates which optional fields are valid */
>   	u8 flags;		/* Miscellaneous info */
>   	u8 highest_dstates[4];	/* _sx_d values: 0xFF indicates not valid */
>   	u8 lowest_dstates[5];	/* _sx_w values: 0xFF indicates not valid */
> @@ -1158,6 +1158,7 @@ struct acpi_device_info {
>   	struct acpi_pnp_device_id unique_id;	/* _UID value */
>   	struct acpi_pnp_device_id subsystem_id;	/* _SUB value */
>   	struct acpi_pnp_device_id_list compatible_id_list;	/* _CID list <must be last> */
> +	struct acpi_pnp_device_id cls;	/* _CLS value */
>   };

Please disregard this patch. I found out a mistake on my part here.  I 
have sent out V5 here (https://lkml.org/lkml/2015/3/6/24)

Thank you,

Suravee