spi: sh-msiof: Add slave mode support

Add slave mode support to the MSIOF driver, in both PIO and DMA mode.

For now this only supports the transmission of messages with a size
that is known in advance.

Signed-off-by: Hisashi Nakamura <hisashi.nakamura.ak@renesas.com>
Signed-off-by: Hiromitsu Yamasaki <hiromitsu.yamasaki.ym@renesas.com>
[geert: Timeout handling cleanup, spi core integration, cancellation,
	rewording]
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
diff --git a/include/linux/spi/sh_msiof.h b/include/linux/spi/sh_msiof.h
index b087a85..f74b581 100644
--- a/include/linux/spi/sh_msiof.h
+++ b/include/linux/spi/sh_msiof.h
@@ -1,10 +1,16 @@
 #ifndef __SPI_SH_MSIOF_H__
 #define __SPI_SH_MSIOF_H__
 
+enum {
+	MSIOF_SPI_MASTER,
+	MSIOF_SPI_SLAVE,
+};
+
 struct sh_msiof_spi_info {
 	int tx_fifo_override;
 	int rx_fifo_override;
 	u16 num_chipselect;
+	int mode;
 	unsigned int dma_tx_id;
 	unsigned int dma_rx_id;
 	u32 dtdl;