The spi_flash_read_env function is a wrapper over spi_flash_read, which enables the env to read multiple flash page size from flash until '\0\0' is read or the end of env partition is reached. Instead of reading the entire env size. When it reads '\0\0', it stops reading further the env and assumes that the rest of env is '\0'.
This is an optimization for large environments that contain few bytes environment variables. In this case it doesn't need to read the entire environment and only few pages.
Signed-off-by: Horatiu Vultur horatiu.vultur@microchip.com --- env/sf.c | 56 +++++++++++++++++++++++++++++++++++++++++++++----------- 1 file changed, 45 insertions(+), 11 deletions(-)
Changes in v2: - rename flash_read to spi_flash_read_env - change signature of is_end, by adding const to addr
diff --git a/env/sf.c b/env/sf.c index 2e3c600..01fadee 100644 --- a/env/sf.c +++ b/env/sf.c @@ -81,6 +81,40 @@ static int setup_flash_device(void) return 0; }
+static int is_end(const char *addr, size_t size) +{ + /* The end of env variables is marked by '\0\0' */ + int i = 0; + + for (i = 0; i < size - 1; ++i) + if (addr[i] == 0x0 && addr[i + 1] == 0x0) + return 1; + return 0; +} + +static int spi_flash_read_env(struct spi_flash *flash, u32 offset, size_t len, + void *buf) +{ + u32 addr = 0; + u32 page_size = flash->page_size; + + memset(buf, 0x0, len); + for (int i = 0; i < len / page_size; ++i) { + int ret = spi_flash_read(flash, offset, page_size, + &((char *)buf)[addr]); + + if (ret < 0) + return ret; + + if (is_end(&((char *)buf)[addr], page_size)) + return 0; + + addr += page_size; + offset += page_size; + } + return 0; +} + #if defined(CONFIG_ENV_OFFSET_REDUND) #ifdef CMD_SAVEENV static int env_sf_save(void) @@ -116,8 +150,8 @@ static int env_sf_save(void) ret = -ENOMEM; goto done; } - ret = spi_flash_read(env_flash, saved_offset, - saved_size, saved_buffer); + ret = spi_flash_read_env(env_flash, saved_offset, + saved_size, saved_buffer); if (ret) goto done; } @@ -183,10 +217,10 @@ static int env_sf_load(void) if (ret) goto out;
- read1_fail = spi_flash_read(env_flash, CONFIG_ENV_OFFSET, - CONFIG_ENV_SIZE, tmp_env1); - read2_fail = spi_flash_read(env_flash, CONFIG_ENV_OFFSET_REDUND, - CONFIG_ENV_SIZE, tmp_env2); + read1_fail = spi_flash_read_env(env_flash, CONFIG_ENV_OFFSET, + CONFIG_ENV_SIZE, tmp_env1); + read2_fail = spi_flash_read_env(env_flash, CONFIG_ENV_OFFSET_REDUND, + CONFIG_ENV_SIZE, tmp_env2);
ret = env_import_redund((char *)tmp_env1, read1_fail, (char *)tmp_env2, read2_fail); @@ -220,8 +254,8 @@ static int env_sf_save(void) if (!saved_buffer) goto done;
- ret = spi_flash_read(env_flash, saved_offset, - saved_size, saved_buffer); + ret = spi_flash_read_env(env_flash, saved_offset, + saved_size, saved_buffer); if (ret) goto done; } @@ -277,10 +311,10 @@ static int env_sf_load(void) if (ret) goto out;
- ret = spi_flash_read(env_flash, - CONFIG_ENV_OFFSET, CONFIG_ENV_SIZE, buf); + ret = spi_flash_read_env(env_flash, CONFIG_ENV_OFFSET, CONFIG_ENV_SIZE, + buf); if (ret) { - set_default_env("spi_flash_read() failed", 0); + set_default_env("spi_flash_read_env() failed", 0); goto err_read; }