mtd: spi-nor-core: Add support for volatile QE bit

Some of Spansion/Cypress chips support volatile version of configuration
registers and it is recommended to update volatile registers in the field
application due to a risk of the non-volatile registers corruption by
power interrupt. This patch adds a function to set Quad Enable bit in CFR1
volatile.

Signed-off-by: Takahiro Kuwano <Takahiro.Kuwano@infineon.com>
Reviewed-by: Jagan Teki <jagan@amarulasolutions.com>

diff --git a/drivers/mtd/spi/spi-nor-core.c b/drivers/mtd/spi/spi-nor-core.c
index 9e85f7d..2b72d65 100644 (file)
--- a/drivers/mtd/spi/spi-nor-core.c
+++ b/drivers/mtd/spi/spi-nor-core.c
@@ -1711,6 +1711,61 @@ static int macronix_quad_enable(struct spi_nor *nor)
 }
 #endif
 
+#ifdef CONFIG_SPI_FLASH_SPANSION
+/**
+ * spansion_quad_enable_volatile() - enable Quad I/O mode in volatile register.
+ * @nor:       pointer to a 'struct spi_nor'
+ * @addr_base: base address of register (can be >0 in multi-die parts)
+ * @dummy:     number of dummy cycles for register read
+ *
+ * It is recommended to update volatile registers in the field application due
+ * to a risk of the non-volatile registers corruption by power interrupt. This
+ * function sets Quad Enable bit in CFR1 volatile.
+ *
+ * Return: 0 on success, -errno otherwise.
+ */
+static int spansion_quad_enable_volatile(struct spi_nor *nor, u32 addr_base,
+                                        u8 dummy)
+{
+       u32 addr = addr_base + SPINOR_REG_ADDR_CFR1V;
+
+       u8 cr;
+       int ret;
+
+       /* Check current Quad Enable bit value. */
+       ret = spansion_read_any_reg(nor, addr, dummy, &cr);
+       if (ret < 0) {
+               dev_dbg(nor->dev,
+                       "error while reading configuration register\n");
+               return -EINVAL;
+       }
+
+       if (cr & CR_QUAD_EN_SPAN)
+               return 0;
+
+       cr |= CR_QUAD_EN_SPAN;
+
+       write_enable(nor);
+
+       ret = spansion_write_any_reg(nor, addr, cr);
+
+       if (ret < 0) {
+               dev_dbg(nor->dev,
+                       "error while writing configuration register\n");
+               return -EINVAL;
+       }
+
+       /* Read back and check it. */
+       ret = spansion_read_any_reg(nor, addr, dummy, &cr);
+       if (ret || !(cr & CR_QUAD_EN_SPAN)) {
+               dev_dbg(nor->dev, "Spansion Quad bit not set\n");
+               return -EINVAL;
+       }
+
+       return 0;
+}
+#endif
+
 #if defined(CONFIG_SPI_FLASH_SPANSION) || defined(CONFIG_SPI_FLASH_WINBOND)
 /*
  * Write status Register and configuration register with 2 bytes

diff --git a/include/linux/mtd/spi-nor.h b/include/linux/mtd/spi-nor.h
index 5bb0688..81df05f 100644 (file)
--- a/include/linux/mtd/spi-nor.h
+++ b/include/linux/mtd/spi-nor.h
@@ -125,6 +125,7 @@
 #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 */
+#define SPINOR_REG_ADDR_CFR1V  0x00800002
 
 /* Used for Micron flashes only. */
 #define SPINOR_OP_RD_EVCR      0x65    /* Read EVCR register */