[PATCH v9 23/28] mtd: spi-nor-core: Perform a Soft Reset on shutdown
Pratyush Yadav
p.yadav at ti.com
Wed May 5 11:41:33 CEST 2021
On probe, the SPI NOR core will put a flash in 8D-8D-8D mode if it
supports it. But Linux as of now expects to get the flash in 1S-1S-1S
mode. Handing the flash to Linux in Octal DTR mode means the kernel will
fail to detect the flash.
So, we need to reset to Power-on-Reset (POR) state before handing off
the flash. A Software Reset command can be used to do this.
One limitation of the soft reset is that it will restore state from
non-volatile registers in some flashes. This means that if the flash was
set to 8D mode in a non-volatile configuration, a soft reset won't help.
This commit assumes that we don't set any non-volatile bits anywhere,
and the flash doesn't have any non-volatile Octal DTR mode
configuration.
Since spi-nor-tiny doesn't (and likely shouldn't) have
spi_nor_soft_reset(), add a dummy spi_nor_remove() for it that does
nothing.
Signed-off-by: Pratyush Yadav <p.yadav at ti.com>
---
drivers/mtd/spi/Kconfig | 7 ++++
drivers/mtd/spi/sf_probe.c | 8 ++++
drivers/mtd/spi/spi-nor-core.c | 68 ++++++++++++++++++++++++++++++++++
include/linux/mtd/spi-nor.h | 17 +++++++++
4 files changed, 100 insertions(+)
diff --git a/drivers/mtd/spi/Kconfig b/drivers/mtd/spi/Kconfig
index a701167dcc..185ebbeb02 100644
--- a/drivers/mtd/spi/Kconfig
+++ b/drivers/mtd/spi/Kconfig
@@ -97,6 +97,13 @@ config SPI_FLASH_SMART_HWCAPS
can support a type of operation in a much more refined way compared
to using flags like SPI_RX_DUAL, SPI_TX_QUAD, etc.
+config SPI_FLASH_SOFT_RESET
+ bool "Software Reset support for SPI NOR flashes"
+ default n
+ help
+ Enable support for xSPI Software Reset. It will be used to switch from
+ Octal DTR mode to legacy mode on shutdown and boot (if enabled).
+
config SPI_FLASH_BAR
bool "SPI flash Bank/Extended address register support"
help
diff --git a/drivers/mtd/spi/sf_probe.c b/drivers/mtd/spi/sf_probe.c
index 3befbe91ca..adb8ca566d 100644
--- a/drivers/mtd/spi/sf_probe.c
+++ b/drivers/mtd/spi/sf_probe.c
@@ -150,6 +150,13 @@ int spi_flash_std_probe(struct udevice *dev)
static int spi_flash_std_remove(struct udevice *dev)
{
+ struct spi_flash *flash = dev_get_uclass_priv(dev);
+ int ret;
+
+ ret = spi_nor_remove(flash);
+ if (ret)
+ return ret;
+
if (CONFIG_IS_ENABLED(SPI_FLASH_MTD))
spi_flash_mtd_unregister();
@@ -176,6 +183,7 @@ U_BOOT_DRIVER(jedec_spi_nor) = {
.remove = spi_flash_std_remove,
.priv_auto = sizeof(struct spi_nor),
.ops = &spi_flash_std_ops,
+ .flags = DM_FLAG_OS_PREPARE,
};
DM_DRIVER_ALIAS(jedec_spi_nor, spansion_m25p16)
diff --git a/drivers/mtd/spi/spi-nor-core.c b/drivers/mtd/spi/spi-nor-core.c
index 10169a8a8f..6e7b1d00f4 100644
--- a/drivers/mtd/spi/spi-nor-core.c
+++ b/drivers/mtd/spi/spi-nor-core.c
@@ -22,6 +22,7 @@
#include <linux/math64.h>
#include <linux/sizes.h>
#include <linux/bitfield.h>
+#include <linux/delay.h>
#include <linux/mtd/mtd.h>
#include <linux/mtd/spi-nor.h>
@@ -200,6 +201,8 @@ struct spi_nor_fixups {
struct spi_nor_flash_parameter *params);
};
+#define SPI_NOR_SRST_SLEEP_LEN 200
+
/**
* spi_nor_get_cmd_ext() - Get the command opcode extension based on the
* extension type.
@@ -2971,6 +2974,71 @@ static int spi_nor_init(struct spi_nor *nor)
return 0;
}
+#ifdef CONFIG_SPI_FLASH_SOFT_RESET
+/**
+ * spi_nor_soft_reset() - perform the JEDEC Software Reset sequence
+ * @nor: the spi_nor structure
+ *
+ * This function can be used to switch from Octal DTR mode to legacy mode on a
+ * flash that supports it. The soft reset is executed in Octal DTR mode.
+ *
+ * Return: 0 for success, -errno for failure.
+ */
+static int spi_nor_soft_reset(struct spi_nor *nor)
+{
+ struct spi_mem_op op;
+ int ret;
+ enum spi_nor_cmd_ext ext;
+
+ ext = nor->cmd_ext_type;
+ nor->cmd_ext_type = SPI_NOR_EXT_REPEAT;
+
+ op = (struct spi_mem_op)SPI_MEM_OP(SPI_MEM_OP_CMD(SPINOR_OP_SRSTEN, 0),
+ SPI_MEM_OP_NO_DUMMY,
+ SPI_MEM_OP_NO_ADDR,
+ SPI_MEM_OP_NO_DATA);
+ spi_nor_setup_op(nor, &op, SNOR_PROTO_8_8_8_DTR);
+ ret = spi_mem_exec_op(nor->spi, &op);
+ if (ret) {
+ dev_warn(nor->dev, "Software reset enable failed: %d\n", ret);
+ goto out;
+ }
+
+ op = (struct spi_mem_op)SPI_MEM_OP(SPI_MEM_OP_CMD(SPINOR_OP_SRST, 0),
+ SPI_MEM_OP_NO_DUMMY,
+ SPI_MEM_OP_NO_ADDR,
+ SPI_MEM_OP_NO_DATA);
+ spi_nor_setup_op(nor, &op, SNOR_PROTO_8_8_8_DTR);
+ ret = spi_mem_exec_op(nor->spi, &op);
+ if (ret) {
+ dev_warn(nor->dev, "Software reset failed: %d\n", ret);
+ goto out;
+ }
+
+ /*
+ * 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, wait for 200ms just to be sure.
+ */
+ udelay(SPI_NOR_SRST_SLEEP_LEN);
+
+out:
+ nor->cmd_ext_type = ext;
+ return ret;
+}
+#endif /* CONFIG_SPI_FLASH_SOFT_RESET */
+
+int spi_nor_remove(struct spi_nor *nor)
+{
+#ifdef CONFIG_SPI_FLASH_SOFT_RESET
+ if (nor->info->flags & SPI_NOR_OCTAL_DTR_READ &&
+ nor->flags & SNOR_F_SOFT_RESET)
+ return spi_nor_soft_reset(nor);
+#endif
+
+ return 0;
+}
+
void spi_nor_set_fixups(struct spi_nor *nor)
{
}
diff --git a/include/linux/mtd/spi-nor.h b/include/linux/mtd/spi-nor.h
index b2159f6319..29ce175156 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) */
@@ -562,4 +564,19 @@ device_node *spi_nor_get_flash_node(struct spi_nor *nor)
*/
int spi_nor_scan(struct spi_nor *nor);
+#if CONFIG_IS_ENABLED(SPI_FLASH_TINY)
+static inline int spi_nor_remove(struct spi_nor *nor)
+{
+ return 0;
+}
+#else
+/**
+ * spi_nor_remove() - perform cleanup before booting to the next stage
+ * @nor: the spi_nor structure
+ *
+ * Return: 0 for success, -errno for failure.
+ */
+int spi_nor_remove(struct spi_nor *nor);
+#endif
+
#endif
--
2.30.0
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