Re: [PATCH] mtd: spi-nor: Add support for flash reset

Hi Venkatesh Yadav Abbarapu,

On 10/28/24 8:03 AM, Venkatesh Yadav Abbarapu wrote:

Add support for spi-nor flash reset via GPIO controller by reading the reset-gpios property.

[Ported from Linux kernel commit 8f1ee9ef71d0 ("mtd: spi-nor: Add support for flash reset") ]

Signed-off-by: Venkatesh Yadav Abbarapu venkatesh.abbarapu@amd.com

drivers/mtd/spi/spi-nor-core.c | 44 ++++++++++++++++++++++++++++++++++ include/linux/mtd/spi-nor.h | 1 + 2 files changed, 45 insertions(+)

diff --git a/drivers/mtd/spi/spi-nor-core.c b/drivers/mtd/spi/spi-nor-core.c index f5c9868bbc..900f66b0e8 100644 --- a/drivers/mtd/spi/spi-nor-core.c +++ b/drivers/mtd/spi/spi-nor-core.c @@ -12,6 +12,7 @@ #include <display_options.h> #include <log.h> #include <watchdog.h> +#include <asm/gpio.h> #include <dm.h> #include <dm/device_compat.h> #include <dm/devres.h> @@ -4401,7 +4402,13 @@ int spi_nor_remove(struct spi_nor *nor) nor->flags & SNOR_F_SOFT_RESET) return spi_nor_soft_reset(nor); #endif

• if (CONFIG_IS_ENABLED(DM_GPIO)) {

• if (nor->flash_gpio_reset) {
  

• 	struct gpio_desc *flash_gpio_reset = nor->flash_gpio_reset;
  
  

• 	dm_gpio_free(flash_gpio_reset->dev, flash_gpio_reset);
  

Since we get the gpio descriptor with a devres-managed function, I think this is unnecessary as the core should do it by itself when removing

• }
  

• } return 0; }

@@ -4448,6 +4455,37 @@ void spi_nor_set_fixups(struct spi_nor *nor) #endif /* SPI_FLASH_MACRONIX */ }

+static int spi_nor_hw_reset(struct spi_nor *nor) +{

• struct udevice *dev = nor->spi->dev;
• int rc;
• nor->flash_gpio_reset = devm_gpiod_get_optional(dev, "reset",

• 					GPIOD_IS_OUT | GPIOD_ACTIVE_LOW);
  

• if (nor->flash_gpio_reset) {

• /*
  

•  * Experimental delay values by looking at different flash device
  

•  * vendors datasheets.
  

•  */
  

• udelay(5);
  

• /* Toggle gpio to reset the flash device. */
  

• rc = dm_gpio_set_value(nor->flash_gpio_reset, 1);
  

• if (rc)
  

• 	return rc;
  

• udelay(150);
  

• rc = dm_gpio_set_value(nor->flash_gpio_reset, 0);
  

• if (rc)
  

• 	return rc;
  

• udelay(1200);
  

This is a bit odd, I would have assumed a proper reset like mmc-pwrseq-emmc or mmc-pwrseq-simple but for nor would have been more appropriate than just guessing which timing would cover all NORs?

• }
• return 0;

+}

• int spi_nor_scan(struct spi_nor *nor) { struct spi_nor_flash_parameter params;

@@ -4473,6 +4511,12 @@ int spi_nor_scan(struct spi_nor *nor)

This function also exists in spi-nor-tiny, should we add support for the hw-reset there as well?

Cheers, Quentin