blob: 822c9a7e2cf488f202cc51534cdb6d06285cf50b [file] [log] [blame] [edit]
/*
* Copyright (c) 2020 Laczen
*
* SPDX-License-Identifier: Apache-2.0
*/
/*
* This driver emulates an EEPROM device in flash.
*
* The emulation represents the EEPROM in flash as a region that is a direct
* map of the EEPROM data (EEPROM data) followed by a region where changes to
* the EEPROM data (EEPROM changes) are stored. The combination of EEPROM data
* and EEPROM changes form a EEPROM page (see drawing below). Changes to EEPROM
* data are written as address-data combinations. The size of such a combination
* is determined by the flash write block size and the size of the EEPROM
* (required address space), with a minimum of 4 byte.
*
* When there is no more space to store changes a new EEPROM page is taken into
* use. This copies the existing data to the EEPROM data area of the new page.
* During this copying the write that is performed is applied at the same time.
* The old page is then invalidated.
*
* The EEPROM page needs to be a multiple of a flash page size. Multiple EEPROM
* pages are also supported and increases the number of writes that can be
* performed.
*
* The representation of the EEPROM on flash is shown in the next graph.
*
* |-----------------------------------------------------------------------|
* ||----------------------| |----------------------| |-------------------||
* || EEPROM data | | | |-Flash page--------||
* || | | | |
* || size = EEPROM size | | | |
* ||----------------------| |----------------------| ... |
* || EEPROM changes: | | | |
* || (address, new data) | | | |
* || | | | |
* || XX| | XX| |
* ||--EEPROM page 0-------| |--EEPROM page 1-------| |
* |------------------------------------------------------------Partition--|
* XX: page validity marker: all 0x00: page invalid
*
* Internally the address of an EEPROM byte is represented by a uint32_t (this
* should be sufficient in all cases). In case the EEPROM size is smaller than
* 64kB only a uint16_t is used to store changes. In this case the change stored
* for a 4 byte flash write block size are a combination of 2 byte address and
* 2 byte data.
*
* The EEPROM size, pagesize and the flash partition used for the EEPROM are
* defined in the dts. The flash partition should allow at least two EEPROM
* pages.
*
*/
#define DT_DRV_COMPAT zephyr_emu_eeprom
#define EEPROM_EMU_VERSION 0
#define EEPROM_EMU_MAGIC 0x45454d55 /* EEMU in hex */
#include <zephyr/drivers/eeprom.h>
#include <zephyr/drivers/flash.h>
#include <zephyr/kernel.h>
#define LOG_LEVEL CONFIG_EEPROM_LOG_LEVEL
#include <zephyr/logging/log.h>
LOG_MODULE_REGISTER(eeprom_emulator);
struct eeprom_emu_config {
/* EEPROM size */
size_t size;
/* EEPROM is read-only */
bool readonly;
/* Page size used to emulate the EEPROM, contains one area of EEPROM
* size and a area to store changes.
*/
size_t page_size;
/* Offset of the flash partition used to emulate the EEPROM */
off_t flash_offset;
/* Size of the flash partition to emulate the EEPROM */
size_t flash_size;
/* Delay the erase of EEPROM pages until the complete partition is used.
*/
bool partitionerase;
/* Size of a change block */
uint8_t flash_cbs;
uint8_t *rambuf;
/* Device of the flash partition used to emulate the EEPROM */
const struct device *flash_dev;
};
struct eeprom_emu_data {
/* Offset in current (EEPROM) page where next change is written */
off_t write_offset;
/* Offset of the current (EEPROM) page */
off_t page_offset;
struct k_mutex lock;
};
/* read/write context */
struct eeprom_emu_ctx {
const void *data; /* pointer to data */
const size_t len; /* data length */
const off_t address; /* eeprom address */
size_t rlen; /* data remaining (unprocessed) length */
};
/*
* basic flash read, only used with offset aligned to flash write block size
*/
static inline int eeprom_emu_flash_read(const struct device *dev, off_t offset,
uint8_t *blk, size_t len)
{
const struct eeprom_emu_config *dev_config = dev->config;
return flash_read(dev_config->flash_dev, dev_config->flash_offset +
offset, blk, len);
}
/*
* basic flash write, only used with offset aligned to flash write block size
*/
static inline int eeprom_emu_flash_write(const struct device *dev, off_t offset,
const uint8_t *blk, size_t len)
{
const struct eeprom_emu_config *dev_config = dev->config;
int rc;
rc = flash_write(dev_config->flash_dev, dev_config->flash_offset +
offset, blk, len);
return rc;
}
/*
* basic flash erase, only used with offset aligned to flash page and len a
* multiple of the flash page size
*/
static inline int eeprom_emu_flash_erase(const struct device *dev, off_t offset,
size_t len)
{
const struct eeprom_emu_config *dev_config = dev->config;
int rc;
rc = flash_erase(dev_config->flash_dev, dev_config->flash_offset +
offset, len);
return rc;
}
/*
* eeprom_emu_page_invalidate: invalidate a page by writing all zeros at the end
*/
static int eeprom_emu_page_invalidate(const struct device *dev, off_t offset)
{
const struct eeprom_emu_config *dev_config = dev->config;
uint8_t buf[dev_config->flash_cbs];
LOG_DBG("Invalidating page at [0x%tx]", (ptrdiff_t)offset);
memset(buf, 0x00, sizeof(buf));
offset += (dev_config->page_size - sizeof(buf));
return eeprom_emu_flash_write(dev, offset, buf, sizeof(buf));
}
/*
* eeprom_emu_get_address: read the address from a change block
*/
static uint32_t eeprom_emu_get_address(const struct device *dev,
const uint8_t *blk)
{
const struct eeprom_emu_config *dev_config = dev->config;
uint32_t address = 0U;
blk += dev_config->flash_cbs / 2;
for (int i = 0; i < sizeof(address); i++) {
if (2 * i == dev_config->flash_cbs) {
break;
}
address += ((uint32_t)(*blk) << (8 * i));
blk++;
}
return address;
}
/*
* eeprom_emu_set_change: create change blocks from data in blk and address
*/
static void eeprom_emu_set_change(const struct device *dev,
const uint32_t address, const uint8_t *data,
uint8_t *blk)
{
const struct eeprom_emu_config *dev_config = dev->config;
for (int i = 0; i < (dev_config->flash_cbs / 2); i++) {
(*blk++) = (*data++);
}
for (int i = 0; i < (dev_config->flash_cbs / 2); i++) {
if (i < sizeof(address)) {
(*blk++) = (uint8_t)(((address >> (8 * i)) & 0xff));
} else {
(*blk++) = 0xff;
}
}
}
/*
* eeprom_emu_is_word_used: check if word is not empty
*/
static int eeprom_emu_is_word_used(const struct device *dev, const uint8_t *blk)
{
const struct eeprom_emu_config *dev_config = dev->config;
for (int i = 0; i < dev_config->flash_cbs; i++) {
if ((*blk++) != 0xff) {
return 1;
}
}
return 0;
}
/*
* eeprom_emu_word_read: read basic word (cbs byte of data) item from
* address directly from flash.
*/
static int eeprom_emu_word_read(const struct device *dev, off_t address,
uint8_t *data)
{
const struct eeprom_emu_config *dev_config = dev->config;
const struct eeprom_emu_data *dev_data = dev->data;
uint8_t buf[dev_config->flash_cbs];
off_t direct_address;
int rc;
direct_address = dev_data->page_offset + address;
/* Direct flash read */
rc = eeprom_emu_flash_read(dev, direct_address, data, sizeof(buf));
if (rc) {
return rc;
}
/* Process changes written to flash */
off_t offset, ch_address;
bool mc1 = false, mc2 = false;
offset = dev_data->write_offset;
while (((!mc1) || (!mc2)) && (offset > dev_config->size)) {
offset -= sizeof(buf);
/* read the change */
rc = eeprom_emu_flash_read(dev, dev_data->page_offset + offset,
buf, sizeof(buf));
if (rc) {
return rc;
}
/* get the address from a change block */
ch_address = eeprom_emu_get_address(dev, buf);
if ((!mc1) && (ch_address == address)) {
memcpy(data, buf, sizeof(buf)/2);
mc1 = true;
}
if ((!mc2) && (ch_address == (address + sizeof(buf)/2))) {
memcpy(data + sizeof(buf)/2, buf, sizeof(buf)/2);
mc2 = true;
}
}
return rc;
}
/* Update data specified in ctx from flash */
static int eeprom_emu_flash_get(const struct device *dev,
struct eeprom_emu_ctx *ctx)
{
const struct eeprom_emu_config *dev_config = dev->config;
off_t address = ctx->address + ctx->len - ctx->rlen;
uint8_t *data8 = (uint8_t *)(ctx->data);
uint8_t buf[dev_config->flash_cbs];
const off_t addr_jmp = address & (sizeof(buf) - 1);
size_t len;
int rc;
data8 += (ctx->len - ctx->rlen);
len = MIN((sizeof(buf) - addr_jmp), ctx->rlen);
rc = eeprom_emu_word_read(dev, address - addr_jmp, buf);
if (rc) {
return rc;
}
memcpy(data8, buf + addr_jmp, len);
ctx->rlen -= len;
return rc;
}
/*
* eeprom_emu_compactor: start a new EEPROM page and copy existing data to the
* new page. During copy update the data with present write data. Invalidate
* the old page.
*/
static int eeprom_emu_compactor(const struct device *dev,
struct eeprom_emu_ctx *ctx)
{
const struct eeprom_emu_config *dev_config = dev->config;
struct eeprom_emu_data *dev_data = dev->data;
off_t next_page_offset;
int rc = 0;
LOG_DBG("Compactor called for page at [0x%tx]",
(ptrdiff_t)dev_data->page_offset);
next_page_offset = dev_data->page_offset + dev_config->page_size;
if (next_page_offset >= dev_config->flash_size) {
next_page_offset = 0;
}
if (!dev_config->partitionerase) {
/* erase the new page */
rc = eeprom_emu_flash_erase(dev, next_page_offset,
dev_config->page_size);
} else if (next_page_offset == 0) {
/* erase the entire partition */
rc = eeprom_emu_flash_erase(dev, next_page_offset,
dev_config->flash_size);
} else {
rc = 0;
}
if (rc) {
return rc;
}
if (dev_config->rambuf && (ctx != NULL)) {
rc = eeprom_emu_flash_write(dev, next_page_offset,
dev_config->rambuf,
dev_config->size);
if (rc) {
return rc;
}
ctx->rlen = 0;
} else {
off_t rd_offset = 0;
uint8_t buf[dev_config->flash_cbs];
/* reset the context if available */
if (ctx != NULL) {
ctx->rlen = ctx->len;
}
/* copy existing data */
while (rd_offset < dev_config->size) {
rc = eeprom_emu_word_read(dev, rd_offset, buf);
if (rc) {
return rc;
}
if ((ctx != NULL) && (ctx->len) &&
(rd_offset > (ctx->address - sizeof(buf)))) {
/* overwrite buf data with context data */
uint8_t *data8 = (uint8_t *)(ctx->data);
off_t address, addr_jmp;
size_t len;
address = ctx->address + ctx->len - ctx->rlen;
addr_jmp = address & (sizeof(buf) - 1);
len = MIN((sizeof(buf) - addr_jmp), ctx->rlen);
data8 += (ctx->len - ctx->rlen);
memcpy(buf + addr_jmp, data8, len);
ctx->rlen -= len;
}
if (eeprom_emu_is_word_used(dev, buf)) {
rc = eeprom_emu_flash_write(dev,
next_page_offset +
rd_offset, buf,
sizeof(buf));
if (rc) {
return rc;
}
}
rd_offset += sizeof(buf);
}
}
if ((dev_config->partitionerase) && (next_page_offset == 0)) {
/* no need to invalidate previous page as it has been deleted */
rc = 0;
} else {
/* invalidate the old page */
rc = eeprom_emu_page_invalidate(dev, dev_data->page_offset);
}
if (!rc) {
dev_data->write_offset = dev_config->size;
dev_data->page_offset = next_page_offset;
}
return rc;
}
/*
* eeprom_emu_word_write: write basic word (cbs bytes of data) item to address,
*/
static int eeprom_emu_word_write(const struct device *dev, off_t address,
const uint8_t *data,
struct eeprom_emu_ctx *ctx)
{
const struct eeprom_emu_config *dev_config = dev->config;
struct eeprom_emu_data *dev_data = dev->data;
uint8_t buf[dev_config->flash_cbs], tmp[dev_config->flash_cbs];
off_t direct_address, wraddr;
int rc;
direct_address = dev_data->page_offset + address;
rc = eeprom_emu_flash_read(dev, direct_address, buf, sizeof(buf));
if (rc) {
return rc;
}
if (!eeprom_emu_is_word_used(dev, buf)) {
if (eeprom_emu_is_word_used(dev, data)) {
rc = eeprom_emu_flash_write(dev, direct_address, data,
sizeof(buf));
}
return rc;
}
rc = eeprom_emu_word_read(dev, address, buf);
if (rc) {
return rc;
}
if (!memcmp(buf, data, sizeof(buf))) {
/* data has not changed */
return rc;
}
wraddr = address;
/* store change */
for (uint8_t i = 0; i < 2; i++) {
if (memcmp(&buf[i*sizeof(buf)/2], data, sizeof(buf)/2)) {
eeprom_emu_set_change(dev, wraddr, data, tmp);
rc = eeprom_emu_flash_write(dev, dev_data->page_offset +
dev_data->write_offset, tmp,
sizeof(buf));
if (rc) {
return rc;
}
dev_data->write_offset += sizeof(buf);
if ((dev_data->write_offset + sizeof(buf)) >=
dev_config->page_size) {
rc = eeprom_emu_compactor(dev, ctx);
return rc;
}
}
data += sizeof(buf)/2;
wraddr += sizeof(buf)/2;
}
return rc;
}
/* Update flash with data specified in ctx */
static int eeprom_emu_flash_set(const struct device *dev,
struct eeprom_emu_ctx *ctx)
{
const struct eeprom_emu_config *dev_config = dev->config;
off_t address = ctx->address + ctx->len - ctx->rlen;
uint8_t *data8 = (uint8_t *)(ctx->data);
uint8_t buf[dev_config->flash_cbs];
const off_t addr_jmp = address & (sizeof(buf) - 1);
size_t len;
int rc;
data8 += (ctx->len - ctx->rlen);
len = MIN((sizeof(buf) - addr_jmp), ctx->rlen);
rc = eeprom_emu_word_read(dev, address - addr_jmp, buf);
if (rc) {
return rc;
}
memcpy(buf + addr_jmp, data8, len);
rc = eeprom_emu_word_write(dev, address - addr_jmp, buf, ctx);
if (rc) {
return rc;
}
if (ctx->rlen) {
ctx->rlen -= len;
}
return rc;
}
static int eeprom_emu_range_is_valid(const struct device *dev, off_t address,
size_t len)
{
const struct eeprom_emu_config *dev_config = dev->config;
if ((address + len) <= dev_config->size) {
return 1;
}
return 0;
}
static int eeprom_emu_read(const struct device *dev, off_t address, void *data,
size_t len)
{
const struct eeprom_emu_config *dev_config = dev->config;
struct eeprom_emu_data *dev_data = dev->data;
struct eeprom_emu_ctx ctx = {
.data = data,
.len = len,
.address = address,
.rlen = len,
};
int rc = 0;
/* Nothing to do */
if (!len) {
return 0;
}
/* Error checking */
if ((!data) || (!eeprom_emu_range_is_valid(dev, address, len))) {
return -EINVAL;
}
if (!device_is_ready(dev_config->flash_dev)) {
LOG_ERR("flash device is not ready");
return -EIO;
}
/* Handle normal case */
LOG_DBG("EEPROM read at [0x%tx] length[%zu]", (ptrdiff_t)address, len);
k_mutex_lock(&dev_data->lock, K_FOREVER);
/* read from rambuffer if possible */
if (dev_config->rambuf) {
memcpy(data, dev_config->rambuf + address, len);
} else {
/* read from flash if no rambuffer */
while (ctx.rlen) {
rc = eeprom_emu_flash_get(dev, &ctx);
if (rc) {
break;
}
}
}
k_mutex_unlock(&dev_data->lock);
return rc;
}
static int eeprom_emu_write(const struct device *dev, off_t address,
const void *data, size_t len)
{
const struct eeprom_emu_config *dev_config = dev->config;
struct eeprom_emu_data *dev_data = dev->data;
struct eeprom_emu_ctx ctx = {
.data = data,
.len = len,
.address = address,
.rlen = len,
};
int rc = 0;
/* Nothing to do */
if (!len) {
return 0;
}
/* Error checking */
if ((!data) || (!eeprom_emu_range_is_valid(dev, address, len))) {
return -EINVAL;
}
if (dev_config->readonly) {
LOG_ERR("attempt to write to read-only device");
return -EACCES;
}
if (!device_is_ready(dev_config->flash_dev)) {
LOG_ERR("flash device is not ready");
return -EIO;
}
/* Handle normal case */
LOG_DBG("EEPROM write at [0x%tx] length[%zu]", (ptrdiff_t)address, len);
k_mutex_lock(&dev_data->lock, K_FOREVER);
/* first update the rambuffer */
if (dev_config->rambuf) {
memcpy(dev_config->rambuf + address, data, len);
}
/* second update the flash */
while (ctx.rlen) {
rc = eeprom_emu_flash_set(dev, &ctx);
if (rc) {
break;
}
}
k_mutex_unlock(&dev_data->lock);
return rc;
}
static size_t eeprom_emu_size(const struct device *dev)
{
const struct eeprom_emu_config *dev_config = dev->config;
return dev_config->size;
}
static int eeprom_emu_init(const struct device *dev)
{
const struct eeprom_emu_config *dev_config = dev->config;
struct eeprom_emu_data *dev_data = dev->data;
off_t offset;
uint8_t buf[dev_config->flash_cbs];
int rc;
k_mutex_init(&dev_data->lock);
if (!device_is_ready(dev_config->flash_dev)) {
__ASSERT(0, "Could not get flash device binding");
return -ENODEV;
}
/* Find the page offset */
dev_data->page_offset = 0U;
dev_data->write_offset = dev_config->page_size - sizeof(buf);
while (dev_data->page_offset < dev_config->flash_size) {
offset = dev_data->page_offset + dev_data->write_offset;
rc = eeprom_emu_flash_read(dev, offset, buf, sizeof(buf));
if (rc) {
return rc;
}
if (!eeprom_emu_is_word_used(dev, buf)) {
break;
}
dev_data->page_offset += dev_config->page_size;
}
if (dev_data->page_offset == dev_config->flash_size) {
__ASSERT(0, "All pages are invalid, is this a EEPROM area?");
return -EINVAL;
}
dev_data->write_offset = dev_config->size;
/* Update the write offset */
while ((dev_data->write_offset + sizeof(buf)) < dev_config->page_size) {
offset = dev_data->page_offset + dev_data->write_offset;
rc = eeprom_emu_flash_read(dev, offset, buf, sizeof(buf));
if (rc) {
return rc;
}
if (!eeprom_emu_is_word_used(dev, buf)) {
break;
}
dev_data->write_offset += sizeof(buf);
}
/* dev_data->write_offset reaches last possible location, compaction
* might have been interrupted: call eeprom_emu_compactor again, but
* only in case we are using a write-enabled eeprom
*/
if ((!dev_config->readonly) &&
((dev_data->write_offset + sizeof(buf)) >= dev_config->page_size)) {
rc = eeprom_emu_compactor(dev, NULL);
if (rc) {
return rc;
}
}
/* Fill the ram buffer if enabled */
if (dev_config->rambuf) {
offset = 0;
while (offset < dev_config->size) {
rc = eeprom_emu_word_read(dev, offset, buf);
if (rc) {
return rc;
}
memcpy(dev_config->rambuf + offset, buf, sizeof(buf));
offset += sizeof(buf);
}
}
return rc;
}
static const struct eeprom_driver_api eeprom_emu_api = {
.read = eeprom_emu_read,
.write = eeprom_emu_write,
.size = eeprom_emu_size,
};
#define EEPROM_PARTITION(n) DT_INST_PHANDLE_BY_IDX(n, partition, 0)
#define PART_WBS(part) \
DT_PROP(COND_CODE_1(DT_NODE_HAS_COMPAT(DT_GPARENT(part), soc_nv_flash),\
(DT_GPARENT(part)), (DT_PARENT(part))), write_block_size)
#define PART_CBS(part, size) (PART_WBS(part) < 4) ? \
((size > (2^16)) ? 8 : 4) : PART_WBS(part)
#define PART_DEV_ID(part) \
COND_CODE_1(DT_NODE_HAS_COMPAT(DT_GPARENT(part), soc_nv_flash), \
(DT_PARENT(DT_GPARENT(part))), (DT_GPARENT(part)))
#define PART_DEV(part) \
DEVICE_DT_GET(PART_DEV_ID(part))
#define RECALC_SIZE(size, cbs) \
(size % cbs) ? ((size + cbs - 1) & ~(cbs - 1)) : size
#define ASSERT_SIZE_PAGESIZE_VALID(size, pagesize, readonly) \
BUILD_ASSERT(readonly ? (size <= pagesize) : (4*size <= 3*pagesize), \
"EEPROM size to big for pagesize")
#define ASSERT_PAGESIZE_PARTSIZE_VALID(pagesize, partsize) \
BUILD_ASSERT(partsize % pagesize == 0U, \
"Partition size not a multiple of pagesize")
#define ASSERT_PAGESIZE_SIZE(pagesize, partsize, onepage) \
BUILD_ASSERT(onepage ? (partsize >= pagesize) : (partsize > pagesize),\
"Partition size to small")
#define EEPROM_EMU_READ_ONLY(n) \
DT_INST_PROP(n, read_only) || \
DT_PROP(EEPROM_PARTITION(n), read_only)
#define EEPROM_EMU_ONEPAGE(n) \
EEPROM_EMU_READ_ONLY(n) || DT_INST_PROP(n, partition_erase)
#define EEPROM_EMU_ENABLE_RAMBUF(n) \
COND_CODE_1(DT_INST_PROP(n, rambuf), (1), \
(COND_CODE_1(DT_INST_PROP(n, partition_erase), (1), (0))))
#define EEPROM_EMU_RAMBUF(n) \
COND_CODE_0(EEPROM_EMU_ENABLE_RAMBUF(n), (), \
(static uint8_t eeprom_emu_##n##_rambuf[DT_INST_PROP(n, size)];))
#define EEPROM_EMU_RAMBUF_LINK(n) \
COND_CODE_0(EEPROM_EMU_ENABLE_RAMBUF(n), (NULL), \
(eeprom_emu_##n##_rambuf))
#define EEPROM_EMU_INIT(n) \
ASSERT_SIZE_PAGESIZE_VALID(DT_INST_PROP(n, size), \
DT_INST_PROP(n, pagesize), EEPROM_EMU_ONEPAGE(n)); \
ASSERT_PAGESIZE_PARTSIZE_VALID(DT_INST_PROP(n, pagesize), \
DT_REG_SIZE(EEPROM_PARTITION(n))); \
ASSERT_PAGESIZE_SIZE(DT_INST_PROP(n, pagesize), \
DT_REG_SIZE(EEPROM_PARTITION(n)), EEPROM_EMU_ONEPAGE(n)); \
EEPROM_EMU_RAMBUF(n) \
static const struct eeprom_emu_config eeprom_emu_##n##_config = { \
.size = RECALC_SIZE( \
DT_INST_PROP(n, size), \
(PART_CBS(EEPROM_PARTITION(n), DT_INST_PROP(n, size))) \
), \
.readonly = EEPROM_EMU_READ_ONLY(n), \
.page_size = DT_INST_PROP(n, pagesize), \
.flash_offset = DT_REG_ADDR(EEPROM_PARTITION(n)), \
.flash_size = DT_REG_SIZE(EEPROM_PARTITION(n)), \
.partitionerase = DT_INST_PROP(n, partition_erase), \
.flash_cbs = PART_CBS(EEPROM_PARTITION(n), \
DT_INST_PROP(n, size)), \
.flash_dev = PART_DEV(EEPROM_PARTITION(n)),\
.rambuf = EEPROM_EMU_RAMBUF_LINK(n), \
}; \
static struct eeprom_emu_data eeprom_emu_##n##_data; \
DEVICE_DT_INST_DEFINE(n, &eeprom_emu_init, \
NULL, &eeprom_emu_##n##_data, \
&eeprom_emu_##n##_config, POST_KERNEL, \
CONFIG_EEPROM_INIT_PRIORITY, &eeprom_emu_api); \
DT_INST_FOREACH_STATUS_OKAY(EEPROM_EMU_INIT)