drivers/flash/flash_simulator: Add write and erase callbacks

Add the functionality that allows to register write and erase callbacks.
The callbacks can modify the behaviour of this operations.
It are meant to be used during testing of the situation when the memory
starts to generate errors or the data cannot be trusted anymore.
It expands the testing possibility, for a situation when the module
is tested that checks the data integrity and and we cannot just jump in
between its internal write and read operations to inject an error.

Signed-off-by: Radosław Koppel <[email protected]>

Author: rkel

drivers/flash/flash_simulator.c

@@ -17,6 +17,8 @@
 #include <zephyr/stats/stats.h>
 #include <string.h>
 
+#include <zephyr/drivers/flash/flash_simulator.h>
+
 #ifdef CONFIG_ARCH_POSIX
 
 #include "flash_simulator_native.h"
@@ -170,6 +172,20 @@ static const struct flash_parameters flash_sim_parameters = {
 	},
 };
 
+static uint8_t *const mock_flash_pointer = mock_flash;
+static const struct flash_simulator_params flash_sim_params = {
+	.memory = &mock_flash_pointer,
+	.memory_size = FLASH_SIMULATOR_FLASH_SIZE,
+	.base_offset = FLASH_SIMULATOR_BASE_OFFSET,
+	.erase_unit = FLASH_SIMULATOR_ERASE_UNIT,
+	.prog_unit = FLASH_SIMULATOR_PROG_UNIT,
+	.explicit_erase = IS_ENABLED(CONFIG_FLASH_SIMULATOR_EXPLICIT_ERASE),
+	.erase_value = FLASH_SIMULATOR_ERASE_VALUE,
+};
+
+static const struct flash_simulator_cb *flash_simulator_cbs;
+
+
 static int flash_range_is_valid(const struct device *dev, off_t offset,
 				size_t len)
 {
@@ -264,6 +280,13 @@ static int flash_sim_write(const struct device *dev, const off_t offset,
 	}
 #endif
 
+	flash_simulator_write_byte_cb_t write_cb = NULL;
+	const struct flash_simulator_cb *cb = flash_simulator_cbs;
+
+	if (cb != NULL) {
+		write_cb = cb->write_byte;
+	}
+
 	for (uint32_t i = 0; i < len; i++) {
 #ifdef CONFIG_FLASH_SIMULATOR_STATS
 		if (data_part_ignored) {
@@ -273,16 +296,26 @@ static int flash_sim_write(const struct device *dev, const off_t offset,
 		}
 #endif /* CONFIG_FLASH_SIMULATOR_STATS */
 
-		/* only pull bits to zero */
+		uint8_t data_val = *((const uint8_t *)data + i);
+
 #if defined(CONFIG_FLASH_SIMULATOR_EXPLICIT_ERASE)
 #if FLASH_SIMULATOR_ERASE_VALUE == 0xFF
-		*(MOCK_FLASH(offset + i)) &= *((uint8_t *)data + i);
+		/* only pull bits to zero */
+		data_val &= *(MOCK_FLASH(offset + i));
 #else
-		*(MOCK_FLASH(offset + i)) |= *((uint8_t *)data + i);
+		/* only pull bits to one */
+		data_val |= *(MOCK_FLASH(offset + i));
 #endif
-#else
-		*(MOCK_FLASH(offset + i)) = *((uint8_t *)data + i);
 #endif
+		if (write_cb != NULL) {
+			int ret = write_cb(dev, &flash_sim_params,
+					   offset + i, data_val);
+			if (ret < 0) {
+				return ret;
+			}
+			data_val = (uint8_t)ret;
+		}
+		*(MOCK_FLASH(offset + i)) = data_val;
 	}
 
 	FLASH_SIM_STATS_INCN(flash_sim_stats, bytes_written, len);
@@ -297,20 +330,28 @@ static int flash_sim_write(const struct device *dev, const off_t offset,
 	return 0;
 }
 
-static void unit_erase(const uint32_t unit)
+static int unit_erase(const struct device *dev, const uint32_t unit)
 {
 	const off_t unit_addr = unit * FLASH_SIMULATOR_ERASE_UNIT;
+	flash_simulator_erase_unit_cb_t erase_cb = NULL;
+	const struct flash_simulator_cb *cb = flash_simulator_cbs;
+
+	if (cb != NULL) {
+		erase_cb = cb->erase_unit;
+	}
+	if (erase_cb != NULL) {
+		return erase_cb(dev, &flash_sim_params, unit_addr);
+	}
 
 	/* erase the memory unit by setting it to erase value */
 	memset(MOCK_FLASH(unit_addr), FLASH_SIMULATOR_ERASE_VALUE,
 	       FLASH_SIMULATOR_ERASE_UNIT);
+	return 0;
 }
 
 static int flash_sim_erase(const struct device *dev, const off_t offset,
 			   const size_t len)
 {
-	ARG_UNUSED(dev);
-
 	if (!flash_range_is_valid(dev, offset, len)) {
 		return -EINVAL;
 	}
@@ -335,8 +376,13 @@ static int flash_sim_erase(const struct device *dev, const off_t offset,
 
 	/* erase as many units as necessary and increase their erase counter */
 	for (uint32_t i = 0; i < len / FLASH_SIMULATOR_ERASE_UNIT; i++) {
+		int ret;
+
 		ERASE_CYCLES_INC(unit_start + i);
-		unit_erase(unit_start + i);
+		ret = unit_erase(dev, unit_start + i);
+		if (ret < 0) {
+			return ret;
+		}
 	}
 
 #ifdef CONFIG_FLASH_SIMULATOR_SIMULATE_TIMING
@@ -498,6 +544,13 @@ void *z_impl_flash_simulator_get_memory(const struct device *dev,
 	return mock_flash;
 }
 
+void z_impl_flash_simulator_set_callbacks(const struct device *dev,
+					  const struct flash_simulator_cb *cb)
+{
+	ARG_UNUSED(dev);
+	flash_simulator_cbs = cb;
+}
+
 #ifdef CONFIG_USERSPACE
 
 #include <zephyr/internal/syscall_handler.h>
@@ -510,6 +563,14 @@ void *z_vrfy_flash_simulator_get_memory(const struct device *dev,
 	return z_impl_flash_simulator_get_memory(dev, mock_size);
 }
 
+void z_vrfy_flash_simulator_set_callbacks(const struct device *dev,
+					 const struct flash_simulator_cb *cb)
+{
+	K_OOPS(K_SYSCALL_SPECIFIC_DRIVER(dev, K_OBJ_DRIVER_FLASH, &flash_sim_api));
+
+	z_impl_flash_simulator_set_callbacks(dev, cb);
+}
+
 #include <zephyr/syscalls/flash_simulator_get_memory_mrsh.c>
 
 #endif /* CONFIG_USERSPACE */

include/zephyr/drivers/flash/flash_simulator.h

@@ -10,13 +10,110 @@
 extern "C" {
 #endif
 
+#include <zephyr/device.h>
+#include <zephyr/types.h>
+#include <sys/types.h>
+
 /**
  * @file
  * @brief Flash simulator specific API.
  *
  * Extension for flash simulator.
  */
 
+/**
+ * @brief Flash simulator parameters structure
+ *
+ * Auxiliary structure containing flash simulator parameters to be used by callbacks
+ * that can modify the behavior of the flash simulator driver.
+ */
+struct flash_simulator_params {
+	uint8_t *const *memory;    /**< @brief The memory pointer */
+	size_t memory_size; /**< @brief The total size of the memory */
+	size_t base_offset; /**< @brief The base offset of the flash simulator */
+	size_t erase_unit;  /**< @brief The erase unit size */
+	size_t prog_unit;   /**< @brief The program unit size */
+	bool explicit_erase; /**< @brief Whether explicit erase is required */
+	uint8_t erase_value; /**< @brief The value used to represent erased memory */
+};
+
+/**
+ * @brief Flash simulator write byte callback type
+ *
+ * Callback used to overwrite single byte write. The callback gets the requested data
+ * and offset as the parameter. The offset is the same offset passed to the flash write.
+ * The callback must return a value to be written at the specified offset or negative value
+ * in case of error.
+ *
+ * @param dev Flash simulator device pointer.
+ * @param params Flash simulator parameters.
+ * @param offset Offset within the flash simulator memory.
+ * @param data Data byte to be written.
+ * @return Value to be written at the specified offset or negative value in case of error.
+ */
+typedef int (*flash_simulator_write_byte_cb_t)(const struct device *dev,
+					       const struct flash_simulator_params *params,
+					       off_t offset,
+					       const uint8_t data);
+
+/**
+ * @brief Flash simulator erase unit callback type
+ *
+ * Callback used to overwrite unit erase operation. The callback gets the unit offset
+ * as the parameter. The offset is the same offset passed to the flash erase. The callback
+ * must return 0 in case of success or negative value in case of error.
+ *
+ * @note If this callback is set, the flash simulator driver will not perform any erase operation
+ * by itself.
+ *
+ * @param dev Flash simulator device pointer.
+ * @param params Flash simulator parameters.
+ * @param unit_offset Offset within the flash simulator memory.
+ * @return 0 in case of success or negative value in case of error.
+ */
+typedef int (*flash_simulator_erase_unit_cb_t)(const struct device *dev,
+					       const struct flash_simulator_params *params,
+					       off_t unit_offset);
+
+/**
+ * @brief Flash simulator callbacks structure
+ *
+ * Structure containing flash simulator operation callbacks.
+ */
+struct flash_simulator_cb {
+	flash_simulator_write_byte_cb_t write_byte; /**< @brief Byte write callback */
+	flash_simulator_erase_unit_cb_t erase_unit; /**< @brief Unit erase callback */
+};
+
+/**
+ * @brief Get pointer to the flash simulator mock flash memory
+ *
+ * This function allows the caller to get the address of the RAM buffer
+ * in which the flash simulator emulates its flash memory content.
+ *
+ * @param[in]  params   flash simulator parameters.
+ * @param[in]  offset   offset within the flash simulator memory.
+ *
+ * @retval pointer to the ram buffer at specified offset
+ */
+static inline uint8_t *flash_simulator_mock_flash(const struct flash_simulator_params *params,
+						  off_t offset)
+{
+	return (*params->memory) + offset;
+}
+
+/**
+ * @brief Set flash simulator callbacks
+ *
+ * This function allows the caller to set custom callbacks for byte write and
+ * unit erase operations performed by the flash simulator.
+ *
+ * @param[in] dev flash simulator device pointer.
+ * @param[in] cb pointer to the structure containing the callbacks.
+ */
+__syscall void flash_simulator_set_callbacks(const struct device *dev,
+					     const struct flash_simulator_cb *cb);
+
 /**
  * @brief Obtain a pointer to the RAM buffer used but by the simulator
  *