soc_flash_nrf_rram.c

/*
 * Copyright (c) 2024 Nordic Semiconductor ASA
 *
 * SPDX-License-Identifier: Apache-2.0
 */

#define DT_DRV_COMPAT nordic_rram_controller

#include <string.h>
#include <zephyr/kernel.h>
#include <zephyr/device.h>
#include <zephyr/drivers/flash.h>
#include <zephyr/logging/log.h>
#include <zephyr/irq.h>
#include <zephyr/sys/barrier.h>
#include <hal/nrf_rramc.h>

#include <zephyr/../../drivers/flash/soc_flash_nrf.h>

/* Note that it is supported to compile this driver for both secure
 * and non-secure images, but non-secure images cannot call
 * nrf_rramc_config_set because NRF_RRAMC_NS does not exist.
 *
 * Instead, when TF-M boots, it will configure RRAMC with this static
 * configuration:
 *
 * nrf_rramc_config_t config = {
 *   .mode_write = true,
 *   .write_buff_size = WRITE_BUFFER_SIZE
 * };
 *
 * nrf_rramc_ready_next_timeout_t params = {
 *   .value = CONFIG_NRF_RRAM_READYNEXT_TIMEOUT_VALUE,
 *   .enable = true,
 * };
 *
 * For more details see NCSDK-26982.
 */

LOG_MODULE_REGISTER(flash_nrf_rram, CONFIG_FLASH_LOG_LEVEL);

#define RRAM DT_INST(0, soc_nv_flash)

#define RRAM_START DT_REG_ADDR(RRAM)
#define RRAM_SIZE  DT_REG_SIZE(RRAM)

#define PAGE_SIZE  DT_PROP(RRAM, erase_block_size)
#define PAGE_COUNT ((RRAM_SIZE) / (PAGE_SIZE))

#define WRITE_BLOCK_SIZE_FROM_DT DT_PROP(RRAM, write_block_size)
#define ERASE_VALUE              0xFF

#ifdef CONFIG_MULTITHREADING
static struct k_sem sem_lock;
#define SYNC_INIT()   k_sem_init(&sem_lock, 1, 1)
#define SYNC_LOCK()   k_sem_take(&sem_lock, K_FOREVER)
#define SYNC_UNLOCK() k_sem_give(&sem_lock)
#else
#define SYNC_INIT()
#define SYNC_LOCK()
#define SYNC_UNLOCK()
#endif /* CONFIG_MULTITHREADING */

#if CONFIG_NRF_RRAM_WRITE_BUFFER_SIZE > 0
#define WRITE_BUFFER_ENABLE   1
#define WRITE_BUFFER_SIZE     CONFIG_NRF_RRAM_WRITE_BUFFER_SIZE
#define WRITE_LINE_SIZE       16 /* In bytes, one line is 128 bits. */
#define WRITE_BUFFER_MAX_SIZE (WRITE_BUFFER_SIZE * WRITE_LINE_SIZE)
BUILD_ASSERT((PAGE_SIZE % (WRITE_LINE_SIZE) == 0), "erase-block-size must be a multiple of 16");
BUILD_ASSERT((WRITE_BLOCK_SIZE_FROM_DT % (WRITE_LINE_SIZE) == 0),
	     "if NRF_RRAM_WRITE_BUFFER_SIZE > 0, then write-block-size must be a multiple of 16");
#else
#define WRITE_BUFFER_ENABLE   0
#define WRITE_BUFFER_SIZE     0
#define WRITE_LINE_SIZE       WRITE_BLOCK_SIZE_FROM_DT
#define WRITE_BUFFER_MAX_SIZE 16 /* In bytes, one line is 128 bits. */
BUILD_ASSERT((PAGE_SIZE % (WRITE_LINE_SIZE) == 0),
	     "erase-block-size must be a multiple of write-block-size");
#endif

#ifndef CONFIG_SOC_FLASH_NRF_RADIO_SYNC_NONE

#if (WRITE_BUFFER_SIZE < 2)
#define FLASH_SLOT_WRITE 500
#elif (WRITE_BUFFER_SIZE < 4)
#define FLASH_SLOT_WRITE 1000
#elif (WRITE_BUFFER_SIZE < 9)
#define FLASH_SLOT_WRITE 2000
#elif (WRITE_BUFFER_SIZE < 17)
#define FLASH_SLOT_WRITE 4000
#else
#define FLASH_SLOT_WRITE 8000 /* longest write takes 7107 us */
#endif

static int write_op(void *context); /* instance of flash_op_handler_t */
static int write_synchronously(off_t addr, const void *data, size_t len);

#endif /* !CONFIG_SOC_FLASH_NRF_RADIO_SYNC_NONE */

static inline bool is_within_bounds(off_t addr, size_t len, off_t boundary_start,
				    size_t boundary_size)
{
	return (addr >= boundary_start && (addr < (boundary_start + boundary_size)) &&
		(len <= (boundary_start + boundary_size - addr)));
}

#if WRITE_BUFFER_ENABLE
static void commit_changes(off_t addr, size_t len)
{
#if !defined(CONFIG_TRUSTED_EXECUTION_NONSECURE)
	if (nrf_rramc_empty_buffer_check(NRF_RRAMC)) {
		/* The internal write-buffer has been committed to RRAM and is now empty. */
		return;
	}
#endif

	if ((len % (WRITE_BUFFER_MAX_SIZE)) == 0) {
		/* Our last operation was buffer size-aligned, so we're done. */
		return;
	}

#if !defined(CONFIG_TRUSTED_EXECUTION_NONSECURE)
	ARG_UNUSED(addr);

	nrf_rramc_task_trigger(NRF_RRAMC, NRF_RRAMC_TASK_COMMIT_WRITEBUF);
#else
	/*
	 * When the commit task is unavailable we need to get creative to
	 * ensure this is committed.
	 *
	 * According to the PS the buffer is committed when "There is a
	 * read operation from a 128-bit word line in the buffer that has
	 * already been written to".
	 *
	 * So we read the last byte that has been written to trigger this
	 * commit.
	 *
	 * If this approach proves to be problematic, e.g. for writes to
	 * write-only memory, then one would have to rely on
	 * READYNEXTTIMEOUT to eventually commit the write.
	 */
	volatile uint8_t dummy_read = *(volatile uint8_t *)(addr + len - 1);
	ARG_UNUSED(dummy_read);
#endif

	barrier_dmem_fence_full();
}
#endif

static void rram_write(off_t addr, const void *data, size_t len)
{
#if !defined(CONFIG_TRUSTED_EXECUTION_NONSECURE)
	nrf_rramc_config_t config = {.mode_write = true, .write_buff_size = WRITE_BUFFER_SIZE};

	nrf_rramc_config_set(NRF_RRAMC, &config);
#endif

	if (data) {
		memcpy((void *)addr, data, len);
	} else {
		memset((void *)addr, ERASE_VALUE, len);
	}

	barrier_dmem_fence_full(); /* Barrier following our last write. */

#if WRITE_BUFFER_ENABLE
	commit_changes(addr, len);
#endif

#if !defined(CONFIG_TRUSTED_EXECUTION_NONSECURE)
	config.mode_write = false;
	nrf_rramc_config_set(NRF_RRAMC, &config);
#endif
}

#ifndef CONFIG_SOC_FLASH_NRF_RADIO_SYNC_NONE
static void shift_write_context(uint32_t shift, struct flash_context *w_ctx)
{
	w_ctx->flash_addr += shift;

	/* NULL data_addr => erase emulation request*/
	if (w_ctx->data_addr) {
		w_ctx->data_addr += shift;
	}

	w_ctx->len -= shift;
}

static int write_op(void *context)
{
	struct flash_context *w_ctx = context;
	size_t len;

	uint32_t i = 0U;

	if (w_ctx->enable_time_limit) {
		nrf_flash_sync_get_timestamp_begin();
	}

	while (w_ctx->len > 0) {
		len = (WRITE_BUFFER_MAX_SIZE < w_ctx->len) ? WRITE_BUFFER_MAX_SIZE : w_ctx->len;

		rram_write(w_ctx->flash_addr, (const void *)w_ctx->data_addr, len);

		shift_write_context(len, w_ctx);

		if (w_ctx->len > 0) {
			i++;

			if (w_ctx->enable_time_limit) {
				if (nrf_flash_sync_check_time_limit(i)) {
					return FLASH_OP_ONGOING;
				}
			}
		}
	}

	return FLASH_OP_DONE;
}

static int write_synchronously(off_t addr, const void *data, size_t len)
{
	struct flash_context context = {
		.data_addr = (uint32_t)data,
		.flash_addr = addr,
		.len = len,
		.enable_time_limit = 1 /* enable time limit */
	};

	struct flash_op_desc flash_op_desc = {.handler = write_op, .context = &context};

	nrf_flash_sync_set_context(FLASH_SLOT_WRITE);
	return nrf_flash_sync_exe(&flash_op_desc);
}

#endif /* !CONFIG_SOC_FLASH_NRF_RADIO_SYNC_NONE */

static int nrf_write(off_t addr, const void *data, size_t len)
{
	int ret = 0;

	if (!is_within_bounds(addr, len, 0, RRAM_SIZE)) {
		return -EINVAL;
	}
	addr += RRAM_START;

	if (!len) {
		return 0;
	}

	LOG_DBG("Write: %p:%zu", (void *)addr, len);

	SYNC_LOCK();

#ifndef CONFIG_SOC_FLASH_NRF_RADIO_SYNC_NONE
	if (nrf_flash_sync_is_required()) {
		ret = write_synchronously(addr, data, len);
	} else
#endif /* !CONFIG_SOC_FLASH_NRF_RADIO_SYNC_NONE */
	{
		rram_write(addr, data, len);
	}

	SYNC_UNLOCK();

	return ret;
}

static int nrf_rram_read(const struct device *dev, off_t addr, void *data, size_t len)
{
	ARG_UNUSED(dev);

	if (!is_within_bounds(addr, len, 0, RRAM_SIZE)) {
		return -EINVAL;
	}
	addr += RRAM_START;

	memcpy(data, (void *)addr, len);

	return 0;
}

static int nrf_rram_write(const struct device *dev, off_t addr, const void *data, size_t len)
{
	ARG_UNUSED(dev);

	if (data == NULL) {
		return -EINVAL;
	}

	return nrf_write(addr, data, len);
}

static int nrf_rram_erase(const struct device *dev, off_t addr, size_t len)
{
	ARG_UNUSED(dev);

	return nrf_write(addr, NULL, len);
}

static const struct flash_parameters *nrf_rram_get_parameters(const struct device *dev)
{
	ARG_UNUSED(dev);

	static const struct flash_parameters parameters = {
		.write_block_size = WRITE_LINE_SIZE,
		.erase_value = ERASE_VALUE,
	};

	return &parameters;
}

#if defined(CONFIG_FLASH_PAGE_LAYOUT)
static void nrf_rram_page_layout(const struct device *dev, const struct flash_pages_layout **layout,
				 size_t *layout_size)
{
	ARG_UNUSED(dev);

	static const struct flash_pages_layout pages_layout = {
		.pages_count = PAGE_COUNT,
		.pages_size = PAGE_SIZE,
	};

	*layout = &pages_layout;
	*layout_size = 1;
}
#endif

static const struct flash_driver_api nrf_rram_api = {
	.read = nrf_rram_read,
	.write = nrf_rram_write,
	.erase = nrf_rram_erase,
	.get_parameters = nrf_rram_get_parameters,
#if defined(CONFIG_FLASH_PAGE_LAYOUT)
	.page_layout = nrf_rram_page_layout,
#endif
};

static int nrf_rram_init(const struct device *dev)
{
	ARG_UNUSED(dev);

	SYNC_INIT();

#ifndef CONFIG_SOC_FLASH_NRF_RADIO_SYNC_NONE
	nrf_flash_sync_init();
#endif /* !CONFIG_SOC_FLASH_NRF_RADIO_SYNC_NONE */

#if !defined(CONFIG_TRUSTED_EXECUTION_NONSECURE) && CONFIG_NRF_RRAM_READYNEXT_TIMEOUT_VALUE > 0
	nrf_rramc_ready_next_timeout_t params = {
		.value = CONFIG_NRF_RRAM_READYNEXT_TIMEOUT_VALUE,
		.enable = true,
	};

	nrf_rramc_ready_next_timeout_set(NRF_RRAMC, &params);
#endif

	return 0;
}

DEVICE_DT_INST_DEFINE(0, nrf_rram_init, NULL, NULL, NULL, POST_KERNEL, CONFIG_FLASH_INIT_PRIORITY,
		      &nrf_rram_api);