drivers: flash: provide api to reset the flash registers

changes enable flash driver to provide api interface to send reset memory
spi command to the spi flash. The reset memory command would bring the
spi flash to its default power-on state and loose all the volatile register
settings.
Flash reset is needed when more than one controller access the flash chip
in a shared mode.

Signed-off-by: Deepti Deshatty <[email protected]>

doc/releases/release-notes-3.5.rst

@@ -60,6 +60,10 @@ Kernel
 * Added support for :c:func:`k_spin_trylock`
 * Added :c:func:`k_object_is_valid` to check if a kernel object is valid. This replaces
   code that has been duplicated throughout the tree.
+* Introduced :c:func:`flash_reset` function. This allows to send SPI commands
+  to flash device for its reset.
+  Support for extra operations is enabled by
+  :kconfig:option:`CONFIG_FLASH_RESET`selected by driver.
 
 Architectures
 *************
@@ -352,6 +356,12 @@ Drivers and Sensors
   * STM32 QSPI driver now supports Jedec SFDP parameter reading.
   * STM32 OSPI driver now supports both Low and High ports of IO manager.
 
+* Introduced new flash API call :c:func:`flash_reset` which calls
+   :c:func:`send_flash_reset` callback provided by a flash driver. This allows to send
+   SPI commands to flash device for its reset. Support for extra operations is
+   enabled by
+  :kconfig:option:`CONFIG_FLASH_RESET`selected by driver.
+
 * FPGA
 
 * Fuel Gauge

drivers/flash/Kconfig

@@ -84,6 +84,12 @@ config FLASH_PAGE_LAYOUT
 	help
 	  Enables API for retrieving the layout of flash memory pages.
 
+config FLASH_RESET
+	bool "API for resetting the flash device"
+	default n
+	help
+	  Enables API for for resetting the flash device to the power on state.
+
 config FLASH_EX_OP_ENABLED
 	bool "API for extended flash operations"
 	depends on FLASH_HAS_EX_OP

drivers/flash/spi_nor.c

@@ -702,6 +702,21 @@ static int spi_nor_read(const struct device *dev, off_t addr, void *dest,
 	return ret;
 }
 
+#if defined(CONFIG_FLASH_RESET)
+static int spi_nor_send_flash_reset(const struct device *dev)
+{
+	int ret = 0;
+	acquire_device(dev);
+
+	ret = spi_nor_cmd_write(dev, SPI_NOR_CMD_RESET_EN);
+	if (!ret)
+		ret = spi_nor_cmd_write(dev, SPI_NOR_CMD_RESET_MEM);
+
+	release_device(dev);
+	return ret;
+}
+#endif
+
 static int spi_nor_write(const struct device *dev, off_t addr,
 			 const void *src,
 			 size_t size)
@@ -1426,6 +1441,9 @@ static const struct flash_driver_api spi_nor_api = {
 	.sfdp_read = spi_nor_sfdp_read,
 	.read_jedec_id = spi_nor_read_jedec_id,
 #endif
+#if defined(CONFIG_FLASH_RESET)
+	.send_flash_reset = spi_nor_send_flash_reset,
+#endif
 };
 
 #ifndef CONFIG_SPI_NOR_SFDP_RUNTIME

include/zephyr/drivers/flash.h

@@ -128,6 +128,10 @@ typedef int (*flash_api_read_jedec_id)(const struct device *dev, uint8_t *id);
 typedef int (*flash_api_ex_op)(const struct device *dev, uint16_t code,
 			       const uintptr_t in, void *out);
 
+#if defined(CONFIG_FLASH_RESET)
+typedef int (*flash_api_send_reset)(const struct device *dev);
+#endif
+
 __subsystem struct flash_driver_api {
 	flash_api_read read;
 	flash_api_write write;
@@ -143,6 +147,9 @@ __subsystem struct flash_driver_api {
 #if defined(CONFIG_FLASH_EX_OP_ENABLED)
 	flash_api_ex_op ex_op;
 #endif /* CONFIG_FLASH_EX_OP_ENABLED */
+#if defined(CONFIG_FLASH_RESET)
+	flash_api_send_reset send_flash_reset;
+#endif
 };
 
 /**
@@ -249,6 +256,31 @@ static inline int z_impl_flash_erase(const struct device *dev, off_t offset,
 	return rc;
 }
 
+#if defined(CONFIG_FLASH_RESET)
+/*
+ *  @brief  Send SPI reset command.
+ *
+ *  This api can be used  to reset the SPI flash memory i.e volatile
+ *  register configurations before SPI access.
+ *  Command also aborts any ongoing internal SPI operations.
+ *
+ *  @param  dev             : flash dev
+ */
+__syscall int flash_reset(const struct device *dev);
+
+static inline int z_impl_flash_reset(const struct device *dev)
+{
+	const struct flash_driver_api *api =
+		(const struct flash_driver_api *)dev->api;
+
+	if (api->send_flash_reset == NULL) {
+		return -ENOTSUP;
+	}
+
+	return (api->send_flash_reset(dev));
+}
+#endif
+
 struct flash_pages_info {
 	off_t start_offset; /* offset from the base of flash address */
 	size_t size;