[U-Boot] [PATCH v10 03/12] drivers: spi: allow limiting reads

Álvaro Fernández Rojas
2018-01-23T16:14:56Z

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>
---
v10: no changes
v9: no changes
v8: no changes
v7: no changes
v6: no changes
v5: no changes
v4: no changes
v3: no changes
v2: no changes

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 51e28bf07b..e40e1c01de 100644
--- a/drivers/mtd/spi/spi_flash.c
+++ b/drivers/mtd/spi/spi_flash.c
@@ -516,6 +516,9 @@ 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 08c7480fda..4787454e59 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;

--
2.11.0