spi: mxs: Allow other chip selects to work

MXS SSP controller may have up to three chip selects per port: SS0, SS1 and SS2.

Currently only SS0 is supported in the mxs_spi driver.

Allow all the three chip select to work by selecting the desired one
in bits 20 and 21 of the HW_SSP_CTRL0 register.

Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Acked-by: Marek Vasut <marex@denx.de>

drivers/spi/mxs_spi.c

@@ -34,6 +34,8 @@
 
 #define	MXS_SPI_MAX_TIMEOUT	1000000
 #define	MXS_SPI_PORT_OFFSET	0x2000
+#define MXS_SSP_CHIPSELECT_MASK		0x00300000
+#define MXS_SSP_CHIPSELECT_SHIFT	20
 
 struct mxs_spi_slave {
 	struct spi_slave	slave;
@@ -65,6 +67,8 @@ struct spi_slave *spi_setup_slave(unsigned int bus, unsigned int cs,
 {
 	struct mxs_spi_slave *mxs_slave;
 	uint32_t addr;
+	struct mx28_ssp_regs *ssp_regs;
+	int reg;
 
 	if (!spi_cs_is_valid(bus, cs)) {
 		printf("mxs_spi: invalid bus %d / chip select %d\n", bus, cs);
@@ -82,7 +86,13 @@ struct spi_slave *spi_setup_slave(unsigned int bus, unsigned int cs,
 	mxs_slave->max_khz = max_hz / 1000;
 	mxs_slave->mode = mode;
 	mxs_slave->regs = (struct mx28_ssp_regs *)addr;
+	ssp_regs = mxs_slave->regs;
 
+	reg = readl(&ssp_regs->hw_ssp_ctrl0);
+	reg &= ~(MXS_SSP_CHIPSELECT_MASK);
+	reg |= cs << MXS_SSP_CHIPSELECT_SHIFT;
+
+	writel(reg, &ssp_regs->hw_ssp_ctrl0);
 	return &mxs_slave->slave;
 }