spi: pxa2xx: Add slave mode support

Tested on an OLPC XO-1.75 machine, where the Embedded Controller happens
to be a SPI master.

Signed-off-by: Lubomir Rintel <lkundrak@v3.sk>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Mark Brown <broonie@kernel.org>
diff --git a/include/linux/spi/pxa2xx_spi.h b/include/linux/spi/pxa2xx_spi.h
index 9ec4c14..b0674e3 100644
--- a/include/linux/spi/pxa2xx_spi.h
+++ b/include/linux/spi/pxa2xx_spi.h
@@ -25,6 +25,7 @@
 struct pxa2xx_spi_master {
 	u16 num_chipselect;
 	u8 enable_dma;
+	bool is_slave;
 
 	/* DMA engine specific config */
 	bool (*dma_filter)(struct dma_chan *chan, void *param);