[resend v2 06/19] drivers: mtd: nand: cadence: Add support for readid command

[dinesh . maniyam]

From: Dinesh Maniyam <dinesh.mani...@intel.com>

Add support for readid command in Cadence NAND driver.
The id is unique and used for flash identification.

Signed-off-by: Dinesh Maniyam <dinesh.mani...@intel.com>

---
v2:
- remove the "this patch is to" commit phrases
---
---
 drivers/mtd/nand/raw/cadence_nand.c | 32 ++++++++++++++++++++++++++++-
 1 file changed, 31 insertions(+), 1 deletion(-)

diff --git a/drivers/mtd/nand/raw/cadence_nand.c 
b/drivers/mtd/nand/raw/cadence_nand.c
index 261ca6b182..83c6b64c1a 100644
--- a/drivers/mtd/nand/raw/cadence_nand.c
+++ b/drivers/mtd/nand/raw/cadence_nand.c
@@ -1949,6 +1949,27 @@ static int cadence_nand_status(struct mtd_info *mtd, 
unsigned int command)
        return 0;
 }
 
+static int cadence_nand_readid(struct mtd_info *mtd, int offset_in_page, 
unsigned int command)
+{
+       struct nand_chip *chip = mtd_to_nand(mtd);
+       u8 addrs = (u8)offset_in_page;
+       int ret = 0;
+
+       ret = cadence_nand_cmd_opcode(chip, command);
+       if (ret)
+               return ret;
+
+       ret = cadence_nand_cmd_address(chip, ONE_CYCLE, &addrs);
+       if (ret)
+               return ret;
+
+       ret = cadence_nand_cmd_data(chip, 8, GCMD_DIR_READ);
+       if (ret)
+               return ret;
+
+       return 0;
+}
+
 static void cadence_nand_cmdfunc(struct mtd_info *mtd, unsigned int command,
                                 int offset_in_page, int page)
 {
@@ -1961,6 +1982,11 @@ static void cadence_nand_cmdfunc(struct mtd_info *mtd, 
unsigned int command,
        case NAND_CMD_STATUS:
                ret = cadence_nand_status(mtd, command);
                break;
+
+       case NAND_CMD_READID:
+               ret = cadence_nand_readid(mtd, offset_in_page, command);
+               break;
+
        /*
         * ecc will override other command for read, write and erase
         */
@@ -1992,8 +2018,12 @@ static u8 cadence_nand_read_byte(struct mtd_info *mtd)
        u32 size = 1;
        u8 val;
 
-       if (cadence->buf_index == 0)
+       if (cadence->buf_index == 0) {
+               if (cadence->cmd == NAND_CMD_READID)
+                       size = 8;
+
                cadence_nand_read_buf(mtd, &cadence->buf[0], size);
+       }
 
        val = *(&cadence->buf[0] + cadence->buf_index);
        cadence->buf_index++;
-- 
2.19.0