scsi: ufs: sysfs: string descriptors

This patch introduces a sysfs group entry for the UFS string descriptors.
The group adds "string_descriptors" folder under the UFS driver
sysfs entry (/sys/bus/platform/drivers/ufshcd/*). The folder will contain
5 files that will show string values defined by the UFS spec:
a manufacturer name, a product name, an OEM id, a serial number and a
product revision.  The full information about the string descriptors
could be found at UFS specifications 2.1.

Signed-off-by: Stanislav Nijnikov <stanislav.nijnikov@wdc.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
diff --git a/drivers/scsi/ufs/ufshcd.h b/drivers/scsi/ufs/ufshcd.h
index 515c6e6..2dad9da 100644
--- a/drivers/scsi/ufs/ufshcd.h
+++ b/drivers/scsi/ufs/ufshcd.h
@@ -842,6 +842,12 @@ static inline bool ufshcd_is_hs_mode(struct ufs_pa_layer_attr *pwr_info)
 }
 
 /* Expose Query-Request API */
+int ufshcd_query_descriptor_retry(struct ufs_hba *hba,
+				  enum query_opcode opcode,
+				  enum desc_idn idn, u8 index,
+				  u8 selector,
+				  u8 *desc_buf, int *buf_len);
+
 int ufshcd_read_desc_param(struct ufs_hba *hba,
 			   enum desc_idn desc_id,
 			   int desc_index,
@@ -850,6 +856,9 @@ int ufshcd_read_desc_param(struct ufs_hba *hba,
 			   u8 param_size);
 int ufshcd_query_flag(struct ufs_hba *hba, enum query_opcode opcode,
 	enum flag_idn idn, bool *flag_res);
+int ufshcd_read_string_desc(struct ufs_hba *hba, int desc_index,
+			    u8 *buf, u32 size, bool ascii);
+
 int ufshcd_hold(struct ufs_hba *hba, bool async);
 void ufshcd_release(struct ufs_hba *hba);