[PATCH v8 09/15] mtd: spi-nor-core: Add support for Read/Write Any Register

[tkuw584924 at gmail.com]

From: Takahiro Kuwano <Takahiro.Kuwano at infineon.com>

Some of Spansion/Cypress chips support Read/Write Any Register commands.
These commands are mainly used to write volatile registers and access to
the registers in second and subsequent die for multi-die package parts.

The Read Any Register instruction (65h) is followed by register address
and dummy cycles, then the selected register byte is returned.

The Write Any Register instruction (71h) is followed by register address
and register byte to write.

Signed-off-by: Takahiro Kuwano <Takahiro.Kuwano at infineon.com>
Reviewed-by: Pratyush Yadav <p.yadav at ti.com>
---
Changes in v8:
  - No change
  
Changes in v7:
  - No change
  
Changes in v6:
  - No change

Changes in v5:
  - Remove unused defines from spi-nor.h

 drivers/mtd/spi/spi-nor-core.c | 25 +++++++++++++++++++++++++
 include/linux/mtd/spi-nor.h    |  2 ++
 2 files changed, 27 insertions(+)

diff --git a/drivers/mtd/spi/spi-nor-core.c b/drivers/mtd/spi/spi-nor-core.c
index 1b84e389ad..36c1756576 100644
--- a/drivers/mtd/spi/spi-nor-core.c
+++ b/drivers/mtd/spi/spi-nor-core.c
@@ -212,6 +212,31 @@ static int spi_nor_write_reg(struct spi_nor *nor, u8 opcode, u8 *buf, int len)
 	return spi_nor_read_write_reg(nor, &op, buf);
 }
 
+#ifdef CONFIG_SPI_FLASH_SPANSION
+static int spansion_read_any_reg(struct spi_nor *nor, u32 addr, u8 dummy,
+				 u8 *val)
+{
+	struct spi_mem_op op =
+			SPI_MEM_OP(SPI_MEM_OP_CMD(SPINOR_OP_RDAR, 1),
+				   SPI_MEM_OP_ADDR(nor->addr_width, addr, 1),
+				   SPI_MEM_OP_DUMMY(dummy / 8, 1),
+				   SPI_MEM_OP_DATA_IN(1, NULL, 1));
+
+	return spi_nor_read_write_reg(nor, &op, val);
+}
+
+static int spansion_write_any_reg(struct spi_nor *nor, u32 addr, u8 val)
+{
+	struct spi_mem_op op =
+			SPI_MEM_OP(SPI_MEM_OP_CMD(SPINOR_OP_WRAR, 1),
+				   SPI_MEM_OP_ADDR(nor->addr_width, addr, 1),
+				   SPI_MEM_OP_NO_DUMMY,
+				   SPI_MEM_OP_DATA_OUT(1, NULL, 1));
+
+	return spi_nor_read_write_reg(nor, &op, &val);
+}
+#endif
+
 static ssize_t spi_nor_read_data(struct spi_nor *nor, loff_t from, size_t len,
 				 u_char *buf)
 {
diff --git a/include/linux/mtd/spi-nor.h b/include/linux/mtd/spi-nor.h
index 47ce8f5f25..a9b389f2af 100644
--- a/include/linux/mtd/spi-nor.h
+++ b/include/linux/mtd/spi-nor.h
@@ -121,6 +121,8 @@
 #define SPINOR_OP_BRWR		0x17	/* Bank register write */
 #define SPINOR_OP_BRRD		0x16	/* Bank register read */
 #define SPINOR_OP_CLSR		0x30	/* Clear status register 1 */
+#define SPINOR_OP_RDAR		0x65	/* Read any register */
+#define SPINOR_OP_WRAR		0x71	/* Write any register */
 
 /* Used for Micron flashes only. */
 #define SPINOR_OP_RD_EVCR	0x65	/* Read EVCR register */
-- 
2.25.1