drivers: spi: allow limiting reads
For some SPI controllers it's not possible to keep the CS active between
transfers and they are limited to a known number of bytes.
This splits spi_flash reads into different iterations in order to respect
the SPI controller limits.
Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>
Reviewed-by: Jagan Teki <jagan@openedev.com>
diff --git a/drivers/mtd/spi/spi_flash.c b/drivers/mtd/spi/spi_flash.c
index 51e28bf..e40e1c0 100644
--- a/drivers/mtd/spi/spi_flash.c
+++ b/drivers/mtd/spi/spi_flash.c
@@ -516,6 +516,9 @@
else
read_len = remain_len;
+ if (spi->max_read_size)
+ read_len = min(read_len, spi->max_read_size);
+
spi_flash_addr(read_addr, cmd);
ret = spi_flash_read_common(flash, cmd, cmdsz, data, read_len);
diff --git a/include/spi.h b/include/spi.h
index 08c7480..4787454 100644
--- a/include/spi.h
+++ b/include/spi.h
@@ -86,6 +86,8 @@
* @cs: ID of the chip select connected to the slave.
* @mode: SPI mode to use for this slave (see SPI mode flags)
* @wordlen: Size of SPI word in number of bits
+ * @max_read_size: If non-zero, the maximum number of bytes which can
+ * be read at once.
* @max_write_size: If non-zero, the maximum number of bytes which can
* be written at once, excluding command bytes.
* @memory_map: Address of read-only SPI flash access.
@@ -102,6 +104,7 @@
#endif
uint mode;
unsigned int wordlen;
+ unsigned int max_read_size;
unsigned int max_write_size;
void *memory_map;