spi: Add parameter for maximum write size

Some SPI controllers (e.g. Intel ICH) have a limit on the number of SPI
bytes that can be written at a time. Add this as a parameter so that
clients of the SPI interface can respect this value.

Signed-off-by: Simon Glass <sjg@chromium.org>

diff --git a/include/spi.h b/include/spi.h
index ebc9652..3fe2e1e 100644 (file)
--- a/include/spi.h
+++ b/include/spi.h
@@ -49,10 +49,13 @@
  *
  *   bus:      ID of the bus that the slave is attached to.
  *   cs:       ID of the chip select connected to the slave.
+ *   max_write_size:   If non-zero, the maximum number of bytes which can
+ *             be written at once, excluding command bytes.
  */
 struct spi_slave {
        unsigned int    bus;
        unsigned int    cs;
+       unsigned int max_write_size;
 };
 
 /*-----------------------------------------------------------------------