scsi: ufs: add read string descriptor api

The string descriptor may consist of up to 126 UNICODE characters.
The number of UNICODE characters is calculated
by (descriptor's length - 2)/2.
In addition the api allows to get the result in an ascii format.

Change-Id: If43453bf5f9a826900c0acc064e8def275c0f7d1
Signed-off-by: Raviv Shvili <rshvili@codeaurora.org>

3 files changed, 94 insertions, 0 deletions

diff --git a/drivers/scsi/ufs/ufs.h b/drivers/scsi/ufs/ufs.h
index b8f68b61a7c2..a597a34b689f 100644
--- a/drivers/scsi/ufs/ufs.h
+++ b/drivers/scsi/ufs/ufs.h
@@ -44,6 +44,7 @@
 #define GENERAL_UPIU_REQUEST_SIZE 32
 #define QUERY_DESC_MAX_SIZE       255
 #define QUERY_DESC_MIN_SIZE       2
+#define QUERY_DESC_HDR_SIZE       2
 #define QUERY_OSF_SIZE            (GENERAL_UPIU_REQUEST_SIZE - \
 					(sizeof(struct utp_upiu_header)))
 
diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index a238db4f305e..3481023af37c 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -40,6 +40,7 @@
 #include <linux/async.h>
 #include <scsi/ufs/ioctl.h>
 #include <linux/devfreq.h>
+#include <linux/nls.h>
 
 #include "ufshcd.h"
 #include "unipro.h"
@@ -280,6 +281,16 @@ static inline void ufshcd_disable_irq(struct ufs_hba *hba)
 	}
 }
 
+/* replace non-printable or non-ASCII characters with spaces */
+static inline void ufshcd_remove_non_printable(char *val)
+{
+	if (!val)
+		return;
+
+	if (*val < 0x20 || *val > 0x7e)
+		*val = ' ';
+}
+
 static void ufshcd_print_host_regs(struct ufs_hba *hba)
 {
 	/*
@@ -2153,6 +2164,84 @@ int ufshcd_read_device_desc(struct ufs_hba *hba, u8 *buf, u32 size)
 }
 
 /**
+ * ufshcd_read_string_desc - read string descriptor
+ * @hba: pointer to adapter instance
+ * @desc_index: descriptor index
+ * @buf: pointer to buffer where descriptor would be read
+ * @size: size of buf
+ * @ascii: if true convert from unicode to ascii characters
+ *
+ * Return 0 in case of success, non-zero otherwise
+ */
+int ufshcd_read_string_desc(struct ufs_hba *hba, int desc_index, u8 *buf,
+				u32 size, bool ascii)
+{
+	int err = 0;
+	int retries;
+
+	for (retries = 0; retries < QUERY_REQ_RETRIES; retries++) {
+		err = ufshcd_read_desc(hba,
+				QUERY_DESC_IDN_STRING, desc_index, buf, size);
+		if (!err)
+			break;
+		dev_dbg(hba->dev, "%s: error %d retrying %d\n", __func__, err,
+			retries);
+	}
+
+	if (err) {
+		dev_err(hba->dev, "%s: reading String Desc failed after %d retries. err = %d\n",
+			__func__, QUERY_REQ_RETRIES, err);
+		goto out;
+	}
+
+	if (ascii) {
+		int desc_len;
+		int ascii_len;
+		int i;
+		char *buff_ascii;
+
+		desc_len = buf[0];
+		/* remove header and divide by 2 to move from UTF16 to UTF8 */
+		ascii_len = (desc_len - QUERY_DESC_HDR_SIZE) / 2 + 1;
+		if (size < ascii_len + QUERY_DESC_HDR_SIZE) {
+			dev_err(hba->dev, "%s: buffer allocated size is too small\n",
+					__func__);
+			err = -ENOMEM;
+			goto out;
+		}
+
+		buff_ascii = kmalloc(ascii_len, GFP_KERNEL);
+		if (!buff_ascii) {
+			dev_err(hba->dev, "%s: Failed allocating %d bytes\n",
+					__func__, ascii_len);
+			err = -ENOMEM;
+			goto out_free_buff;
+		}
+
+		/*
+		 * the descriptor contains string in UTF16 format
+		 * we need to convert to utf-8 so it can be displayed
+		 */
+		utf16s_to_utf8s((wchar_t *)&buf[QUERY_DESC_HDR_SIZE],
+				desc_len - QUERY_DESC_HDR_SIZE,
+				UTF16_BIG_ENDIAN, buff_ascii, ascii_len);
+
+		/* replace non-printable or non-ASCII characters with spaces */
+		for (i = 0; i < ascii_len; i++)
+			ufshcd_remove_non_printable(&buff_ascii[i]);
+
+		memset(buf + QUERY_DESC_HDR_SIZE, 0,
+				size - QUERY_DESC_HDR_SIZE);
+		memcpy(buf + QUERY_DESC_HDR_SIZE, buff_ascii, ascii_len);
+		buf[QUERY_DESC_LENGTH_OFFSET] = ascii_len + QUERY_DESC_HDR_SIZE;
+out_free_buff:
+		kfree(buff_ascii);
+	}
+out:
+	return err;
+}
+
+/**
  * ufshcd_read_unit_desc_param - read the specified unit descriptor parameter
  * @hba: Pointer to adapter instance
  * @lun: lun id
diff --git a/drivers/scsi/ufs/ufshcd.h b/drivers/scsi/ufs/ufshcd.h
index 34a9cc841217..51912dc59f76 100644
--- a/drivers/scsi/ufs/ufshcd.h
+++ b/drivers/scsi/ufs/ufshcd.h
@@ -778,6 +778,10 @@ static inline int ufshcd_dme_peer_get(struct ufs_hba *hba,
 
 int ufshcd_read_device_desc(struct ufs_hba *hba, u8 *buf, u32 size);
 
+#define ASCII_STD true
+#define UTF16_STD false
+int ufshcd_read_string_desc(struct ufs_hba *hba, int desc_index, u8 *buf,
+				u32 size, bool ascii);
 /* variant specific ops structures */
 #ifdef CONFIG_SCSI_UFS_MSM
 extern const struct ufs_hba_variant_ops ufs_hba_msm_vops;