spi: dw: add support for gpio controlled chip select

Also, use this opportunity to let spi_chip_sel() handle chip-select
deactivation as well.

Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Mark Brown <broonie@linaro.org>

3 files changed, 45 insertions, 11 deletions

diff --git a/drivers/spi/spi-dw-mmio.c b/drivers/spi/spi-dw-mmio.c
index 1492f5ee9aaa..a5cba14ac3d2 100644
--- a/drivers/spi/spi-dw-mmio.c
+++ b/drivers/spi/spi-dw-mmio.c
@@ -16,6 +16,7 @@
 #include <linux/spi/spi.h>
 #include <linux/scatterlist.h>
 #include <linux/module.h>
+#include <linux/of_gpio.h>
 
 #include "spi-dw.h"
 
@@ -70,6 +71,27 @@ static int dw_spi_mmio_probe(struct platform_device *pdev)
         dws->num_cs = 4;
         dws->max_freq = clk_get_rate(dwsmmio->clk);
 
+        if (pdev->dev.of_node) {
+                int i;
+
+                for (i = 0; i < dws->num_cs; i++) {
+                        int cs_gpio = of_get_named_gpio(pdev->dev.of_node,
+                                        "cs-gpios", i);
+
+                        if (cs_gpio == -EPROBE_DEFER) {
+                                ret = cs_gpio;
+                                goto out;
+                        }
+
+                        if (gpio_is_valid(cs_gpio)) {
+                                ret = devm_gpio_request(&pdev->dev, cs_gpio,
+                                                dev_name(&pdev->dev));
+                                if (ret)
+                                        goto out;
+                        }
+                }
+        }
+
         ret = dw_spi_add_host(&pdev->dev, dws);
         if (ret)
                 goto out;
diff --git a/drivers/spi/spi-dw.c b/drivers/spi/spi-dw.c
index 357869a704d6..9965e1b84832 100644
--- a/drivers/spi/spi-dw.c
+++ b/drivers/spi/spi-dw.c
@@ -24,6 +24,7 @@
 #include <linux/delay.h>
 #include <linux/slab.h>
 #include <linux/spi/spi.h>
+#include <linux/gpio.h>
 
 #include "spi-dw.h"
 
@@ -36,9 +37,6 @@
 #define DONE_STATE      ((void *)2)
 #define ERROR_STATE     ((void *)-1)
 
-#define MRST_SPI_DEASSERT       0
-#define MRST_SPI_ASSERT         1
-
 /* Slave spi_dev related */
 struct chip_data {
         u16 cr0;
@@ -272,8 +270,8 @@ static void giveback(struct dw_spi *dws)
         last_transfer = list_last_entry(&msg->transfers, struct spi_transfer,
                                         transfer_list);
 
-        if (!last_transfer->cs_change && dws->cs_control)
-                dws->cs_control(MRST_SPI_DEASSERT);
+        if (!last_transfer->cs_change)
+                spi_chip_sel(dws, dws->cur_msg->spi, 0);
 
         spi_finalize_current_message(dws->master);
 }
@@ -493,7 +491,7 @@ static void pump_transfers(unsigned long data)
                         dw_writew(dws, DW_SPI_CTRL0, cr0);
 
                 spi_set_clk(dws, clk_div ? clk_div : chip->clk_div);
-                spi_chip_sel(dws, spi->chip_select);
+                spi_chip_sel(dws, spi, 1);
 
                 /* Set the interrupt mask, for poll mode just disable all int */
                 spi_mask_intr(dws, 0xff);
@@ -544,6 +542,7 @@ static int dw_spi_setup(struct spi_device *spi)
 {
         struct dw_spi_chip *chip_info = NULL;
         struct chip_data *chip;
+        int ret;
 
         /* Only alloc on first setup */
         chip = spi_get_ctldata(spi);
@@ -597,6 +596,13 @@ static int dw_spi_setup(struct spi_device *spi)
                         | (spi->mode  << SPI_MODE_OFFSET)
                         | (chip->tmode << SPI_TMOD_OFFSET);
 
+        if (gpio_is_valid(spi->cs_gpio)) {
+                ret = gpio_direction_output(spi->cs_gpio,
+                                !(spi->mode & SPI_CS_HIGH));
+                if (ret)
+                        return ret;
+        }
+
         return 0;
 }
 
diff --git a/drivers/spi/spi-dw.h b/drivers/spi/spi-dw.h
index 3fd7ab599ab4..6d2acad34f64 100644
--- a/drivers/spi/spi-dw.h
+++ b/drivers/spi/spi-dw.h
@@ -3,6 +3,7 @@
 
 #include <linux/io.h>
 #include <linux/scatterlist.h>
+#include <linux/gpio.h>
 
 /* Register offsets */
 #define DW_SPI_CTRL0                    0x00
@@ -178,15 +179,20 @@ static inline void spi_set_clk(struct dw_spi *dws, u16 div)
         dw_writel(dws, DW_SPI_BAUDR, div);
 }
 
-static inline void spi_chip_sel(struct dw_spi *dws, u16 cs)
+static inline void spi_chip_sel(struct dw_spi *dws, struct spi_device *spi,
+                int active)
 {
-        if (cs > dws->num_cs)
-                return;
+        u16 cs = spi->chip_select;
+        int gpio_val = active ? (spi->mode & SPI_CS_HIGH) :
+                !(spi->mode & SPI_CS_HIGH);
 
         if (dws->cs_control)
-                dws->cs_control(1);
+                dws->cs_control(active);
+        if (gpio_is_valid(spi->cs_gpio))
+                gpio_set_value(spi->cs_gpio, gpio_val);
 
-        dw_writel(dws, DW_SPI_SER, 1 << cs);
+        if (active)
+                dw_writel(dws, DW_SPI_SER, 1 << cs);
 }
 
 /* Disable IRQ bits */