cxl/mbox: Add Clear Log mailbox command

Adding UAPI support for CXL r3.1 8.2.9.5.4
Clear Log command.

This proposed patch will be useful for clearing and populating
the Vendor debug log in certain scenarios, allowing for the
aggregation of results over time.

Signed-off-by: Srinivasulu Thanneeru <[e-mail]>
Reviewed-by: Jonathan Cameron <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Dave Jiang <[e-mail]>

drivers/cxl/core/mbox.c

···
 	CXL_CMD(GET_HEALTH_INFO, 0, 0x12, 0),
 	CXL_CMD(GET_LOG, 0x18, CXL_VARIABLE_PAYLOAD, CXL_CMD_FLAG_FORCE_ENABLE),
 	CXL_CMD(GET_LOG_CAPS, 0x10, 0x4, 0),
+	CXL_CMD(CLEAR_LOG, 0x10, 0, 0),
 	CXL_CMD(GET_SUP_LOG_SUBLIST, 0x2, CXL_VARIABLE_PAYLOAD, 0),
 	CXL_CMD(SET_PARTITION_INFO, 0x0a, 0, 0),
 	CXL_CMD(SET_LSA, CXL_VARIABLE_PAYLOAD, 0, 0),
···
 		if (pi->flags & CXL_SET_PARTITION_IMMEDIATE_FLAG)
 			return false;
 		break;
+	}
+	case CXL_MBOX_OP_CLEAR_LOG: {
+		const uuid_t *uuid = (uuid_t *)payload_in;
+
+		/*
+		 * Restrict the ‘Clear log’ action to only apply to
+		 * Vendor debug logs.
+		 */
+		return uuid_equal(uuid, &DEFINE_CXL_VENDOR_DEBUG_UUID);
 	}
 	default:
 		break;

drivers/cxl/cxlmem.h

···
 	CXL_MBOX_OP_GET_SUPPORTED_LOGS	= 0x0400,
 	CXL_MBOX_OP_GET_LOG		= 0x0401,
 	CXL_MBOX_OP_GET_LOG_CAPS	= 0x0402,
+	CXL_MBOX_OP_CLEAR_LOG           = 0x0403,
 	CXL_MBOX_OP_GET_SUP_LOG_SUBLIST = 0x0405,
 	CXL_MBOX_OP_IDENTIFY		= 0x4000,
 	CXL_MBOX_OP_GET_PARTITION_INFO	= 0x4100,

include/uapi/linux/cxl_mem.h

···
 	___DEPRECATED(GET_SCAN_MEDIA, "Get Scan Media Results"),          \
 	___C(GET_TIMESTAMP, "Get Timestamp"),                             \
 	___C(GET_LOG_CAPS, "Get Log Capabilities"),			  \
+	___C(CLEAR_LOG, "Clear Log"),					  \
 	___C(GET_SUP_LOG_SUBLIST, "Get Supported Logs Sub-List"),	  \
 	___C(MAX, "invalid / last command")