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Subject[PATCH v3 10/12] mtd: spi-nor: perform a Soft Reset on shutdown
Date
A Software Reset sequence will return the flash to Power-on-Reset (POR)
state. It consists of two commands: Soft Reset Enable and Soft Reset.

Perform a Soft Reset on shutdown on flashes that support it so that the
flash can be reset to its initial state and any configurations made by
spi-nor (given that they're only done in volatile registers) will be
reset. This will hand back the flash in pristine state for any further
operations on it.

Signed-off-by: Pratyush Yadav <p.yadav@ti.com>
---
drivers/mtd/spi-nor/spi-nor.c | 50 +++++++++++++++++++++++++++++++++++
include/linux/mtd/spi-nor.h | 3 +++
2 files changed, 53 insertions(+)

diff --git a/drivers/mtd/spi-nor/spi-nor.c b/drivers/mtd/spi-nor/spi-nor.c
index 5e225d1b29f7..fcc087ff5148 100644
--- a/drivers/mtd/spi-nor/spi-nor.c
+++ b/drivers/mtd/spi-nor/spi-nor.c
@@ -253,6 +253,7 @@ struct flash_info {
* SPI_NOR_HAS_TB.
*/
#define SPI_NOR_OCTAL_DTR_READ BIT(18) /* Flash supports octal DTR Read. */
+#define SPI_NOR_SOFT_RESET BIT(19) /* Flash supports soft reset command */

/* Part specific fixup hooks. */
const struct spi_nor_fixups *fixups;
@@ -260,6 +261,9 @@ struct flash_info {

#define JEDEC_MFR(info) ((info)->id[0])

+#define SPI_NOR_SRST_SLEEP_MIN 200
+#define SPI_NOR_SRST_SLEEP_MAX 400
+
/**
* spi_nor_get_cmd_ext() - Get the command opcode extension based on the
* extension type.
@@ -5336,6 +5340,45 @@ static int spi_nor_init(struct spi_nor *nor)
return 0;
}

+static void spi_nor_soft_reset(struct spi_nor *nor)
+{
+ struct spi_mem_op op;
+ int ret;
+
+ op = (struct spi_mem_op)SPI_MEM_OP(SPI_MEM_OP_CMD(SPINOR_OP_SRSTEN, 8),
+ SPI_MEM_OP_NO_DUMMY,
+ SPI_MEM_OP_NO_ADDR,
+ SPI_MEM_OP_NO_DATA);
+ op.cmd.dtr = op.addr.dtr = op.dummy.dtr = op.data.dtr = true;
+ op.cmd.opcode <<= 8;
+ op.cmd.opcode |= spi_nor_get_cmd_ext(nor, &op);
+ ret = spi_mem_exec_op(nor->spimem, &op);
+ if (ret) {
+ dev_warn(nor->dev, "Software reset failed: %d\n", ret);
+ return;
+ }
+
+ op = (struct spi_mem_op)SPI_MEM_OP(SPI_MEM_OP_CMD(SPINOR_OP_SRST, 8),
+ SPI_MEM_OP_NO_DUMMY,
+ SPI_MEM_OP_NO_ADDR,
+ SPI_MEM_OP_NO_DATA);
+ op.cmd.dtr = op.addr.dtr = op.dummy.dtr = op.data.dtr = true;
+ op.cmd.opcode <<= 8;
+ op.cmd.opcode |= spi_nor_get_cmd_ext(nor, &op);
+ ret = spi_mem_exec_op(nor->spimem, &op);
+ if (ret) {
+ dev_warn(nor->dev, "Software reset failed: %d\n", ret);
+ return;
+ }
+
+ /*
+ * Software Reset is not instant, and the delay varies from flash to
+ * flash. Looking at a few flashes, most range somewhere below 100
+ * microseconds. So, sleep for a range of 200-400 us.
+ */
+ usleep_range(SPI_NOR_SRST_SLEEP_MIN, SPI_NOR_SRST_SLEEP_MAX);
+}
+
/* mtd resume handler */
static void spi_nor_resume(struct mtd_info *mtd)
{
@@ -5355,6 +5398,10 @@ void spi_nor_restore(struct spi_nor *nor)
if (nor->addr_width == 4 && !(nor->flags & SNOR_F_4B_OPCODES) &&
nor->flags & SNOR_F_BROKEN_RESET)
nor->params.set_4byte(nor, false);
+
+ if (nor->info->flags & SPI_NOR_OCTAL_DTR_READ &&
+ nor->flags & SNOR_F_SOFT_RESET)
+ spi_nor_soft_reset(nor);
}
EXPORT_SYMBOL_GPL(spi_nor_restore);

@@ -5539,6 +5586,9 @@ int spi_nor_scan(struct spi_nor *nor, const char *name,
nor->flags |= SNOR_F_HAS_SR_TB_BIT6;
}

+ if (info->flags & SPI_NOR_SOFT_RESET)
+ nor->flags |= SNOR_F_SOFT_RESET;
+
if (info->flags & NO_CHIP_ERASE)
nor->flags |= SNOR_F_NO_OP_CHIP_ERASE;
if (info->flags & USE_CLSR)
diff --git a/include/linux/mtd/spi-nor.h b/include/linux/mtd/spi-nor.h
index 923bd34ced84..13679197dec1 100644
--- a/include/linux/mtd/spi-nor.h
+++ b/include/linux/mtd/spi-nor.h
@@ -67,6 +67,8 @@
#define SPINOR_OP_CLFSR 0x50 /* Clear flag status register */
#define SPINOR_OP_RDEAR 0xc8 /* Read Extended Address Register */
#define SPINOR_OP_WREAR 0xc5 /* Write Extended Address Register */
+#define SPINOR_OP_SRSTEN 0x66 /* Software Reset Enable */
+#define SPINOR_OP_SRST 0x99 /* Software Reset */

/* 4-byte address opcodes - used on Spansion and some Macronix flashes. */
#define SPINOR_OP_READ_4B 0x13 /* Read data bytes (low frequency) */
@@ -241,6 +243,7 @@ enum spi_nor_option_flags {
SNOR_F_HAS_16BIT_SR = BIT(9),
SNOR_F_NO_READ_CR = BIT(10),
SNOR_F_HAS_SR_TB_BIT6 = BIT(11),
+ SNOR_F_SOFT_RESET = BIT(12),

};

--
2.25.0
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