[U-Boot] [PATCH 01/10] drivers: spi: allow limiting reads

Álvaro Fernández Rojas
2017-05-18T19:29:39Z

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>
---
drivers/mtd/spi/spi_flash.c | 3 +++
include/spi.h | 3 +++
2 files changed, 6 insertions(+)

diff --git a/drivers/mtd/spi/spi_flash.c b/drivers/mtd/spi/spi_flash.c
index ab7910b..e44c10f 100644
--- a/drivers/mtd/spi/spi_flash.c
+++ b/drivers/mtd/spi/spi_flash.c
@@ -487,6 +487,9 @@ int spi_flash_cmd_read_ops(struct spi_flash *flash, u32 offset,
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 deb65ef..75a994c 100644
--- a/include/spi.h
+++ b/include/spi.h
@@ -86,6 +86,8 @@ struct dm_spi_slave_platdata {
* @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 @@ struct spi_slave {
#endif
uint mode;
unsigned int wordlen;
+ unsigned int max_read_size;
unsigned int max_write_size;
void *memory_map;
u8 option;
--
2.1.4