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.
Signed-off-by: Pratyush Yadav p.yadav@ti.com --- drivers/mtd/spi/sf_probe.c | 9 +++++ drivers/mtd/spi/spi-nor-core.c | 64 ++++++++++++++++++++++++++++++++++ include/linux/mtd/spi-nor.h | 10 ++++++ 3 files changed, 83 insertions(+)
diff --git a/drivers/mtd/spi/sf_probe.c b/drivers/mtd/spi/sf_probe.c index c2e51f9c68..fc658418e0 100644 --- a/drivers/mtd/spi/sf_probe.c +++ b/drivers/mtd/spi/sf_probe.c @@ -153,6 +153,14 @@ int spi_flash_std_probe(struct udevice *dev)
static int spi_flash_std_remove(struct udevice *dev) { + struct spi_flash *flash; + int ret; + + flash = dev_get_uclass_priv(dev); + ret = spi_nor_remove(flash); + if (ret) + return ret; + #if CONFIG_IS_ENABLED(SPI_FLASH_MTD) spi_flash_mtd_unregister(); #endif @@ -179,6 +187,7 @@ U_BOOT_DRIVER(spi_flash_std) = { .remove = spi_flash_std_remove, .priv_auto_alloc_size = sizeof(struct spi_flash), .ops = &spi_flash_std_ops, + .flags = DM_FLAG_OS_PREPARE, };
#endif /* CONFIG_DM_SPI_FLASH */ diff --git a/drivers/mtd/spi/spi-nor-core.c b/drivers/mtd/spi/spi-nor-core.c index 03bf34a3c9..ca445d7278 100644 --- a/drivers/mtd/spi/spi-nor-core.c +++ b/drivers/mtd/spi/spi-nor-core.c @@ -20,6 +20,7 @@ #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> @@ -198,6 +199,8 @@ 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. @@ -2883,6 +2886,67 @@ static int spi_nor_init(struct spi_nor *nor) return 0; }
+/** + * 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, 8), + 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, 8), + 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; +} + +int spi_nor_remove(struct spi_nor *nor) +{ + if (nor->info->flags & SPI_NOR_OCTAL_DTR_READ && + nor->flags & SNOR_F_SOFT_RESET) + return spi_nor_soft_reset(nor); + + return 0; +} + int spi_nor_scan(struct spi_nor *nor) { struct spi_nor_flash_parameter params; diff --git a/include/linux/mtd/spi-nor.h b/include/linux/mtd/spi-nor.h index 0850f1d775..d8cebf1dcf 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) */ @@ -557,4 +559,12 @@ device_node *spi_nor_get_flash_node(struct spi_nor *nor) */ int spi_nor_scan(struct spi_nor *nor);
+/** + * 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