[PATCH 2/2] spi: spi-mpc512x-psc: add support for gpio chip selects

[Anatolij Gustschin <agust-ynQEQJNshbs@public.gmane.org>]

Currently the driver only uses one internal chip select. Add support
for gpio chip selects configured by gpio specifiers in the device tree.

Signed-off-by: Anatolij Gustschin <agust-ynQEQJNshbs@public.gmane.org>
---
 drivers/spi/spi-mpc512x-psc.c |   80 ++++++++++++++++++++++++++++++++++++++---
 1 files changed, 75 insertions(+), 5 deletions(-)

diff --git a/drivers/spi/spi-mpc512x-psc.c b/drivers/spi/spi-mpc512x-psc.c
index 89480b2..4b2f391 100644
--- a/drivers/spi/spi-mpc512x-psc.c
+++ b/drivers/spi/spi-mpc512x-psc.c
@@ -20,6 +20,7 @@
 #include <linux/errno.h>
 #include <linux/interrupt.h>
 #include <linux/of_address.h>
+#include <linux/of_gpio.h>
 #include <linux/of_platform.h>
 #include <linux/workqueue.h>
 #include <linux/completion.h>
@@ -50,6 +51,8 @@ struct mpc512x_psc_spi {
 	spinlock_t lock;	/* Message queue lock */
 
 	struct completion done;
+	int num_cs;
+	int chipselects[0];
 };
 
 /* controller state */
@@ -277,6 +280,7 @@ static int mpc512x_psc_spi_setup(struct spi_device *spi)
 {
 	struct mpc512x_psc_spi *mps = spi_master_get_devdata(spi->master);
 	struct mpc512x_psc_spi_cs *cs = spi->controller_state;
+	int gpio = mps->chipselects[spi->chip_select];
 	unsigned long flags;
 
 	if (spi->bits_per_word % 8)
@@ -292,6 +296,9 @@ static int mpc512x_psc_spi_setup(struct spi_device *spi)
 	cs->bits_per_word = spi->bits_per_word;
 	cs->speed_hz = spi->max_speed_hz;
 
+	if (gpio_is_valid(gpio))
+		gpio_direction_output(gpio, spi->mode & SPI_CS_HIGH ? 0 : 1);
+
 	spin_lock_irqsave(&mps->lock, flags);
 	if (!mps->busy)
 		mpc512x_psc_spi_deactivate_cs(spi);
@@ -405,6 +412,27 @@ static irqreturn_t mpc512x_psc_spi_isr(int irq, void *dev_id)
 	return IRQ_NONE;
 }
 
+static void mpc512x_spi_cs_control(struct spi_device *spi, bool on)
+{
+	struct mpc512x_psc_spi *mps = spi_master_get_devdata(spi->master);
+	int gpio = mps->chipselects[spi->chip_select];
+
+	gpio_set_value(gpio, on);
+}
+
+static int mpc512x_spi_cs_num(struct device *dev)
+{
+	int num_cs, ret;
+
+	ret = of_property_read_u32(dev->of_node, "num-cs", &num_cs);
+	if (ret < 0) {
+		dev_warn(dev, "no num-cs property\n");
+		return of_gpio_named_count(dev->of_node, "cs-gpios");
+	}
+
+	return num_cs;
+}
+
 /* bus_num is used only for the case dev->platform_data == NULL */
 static int mpc512x_psc_spi_do_probe(struct device *dev, u32 regaddr,
 					      u32 size, unsigned int irq,
@@ -415,8 +443,17 @@ static int mpc512x_psc_spi_do_probe(struct device *dev, u32 regaddr,
 	struct spi_master *master;
 	int ret;
 	void *tempp;
+	int i = 0, max_cs_num = 0;
+	int use_internal_cs = 0;
+	int num_cs;
+
+	num_cs = mpc512x_spi_cs_num(dev);
+	if (!num_cs)
+		use_internal_cs = 1;
 
-	master = spi_alloc_master(dev, sizeof *mps);
+	dev_dbg(dev, "using %d gpio chipselects\n", num_cs);
+
+	master = spi_alloc_master(dev, sizeof(*mps) + sizeof(int) * num_cs);
 	if (master == NULL)
 		return -ENOMEM;
 
@@ -425,12 +462,14 @@ static int mpc512x_psc_spi_do_probe(struct device *dev, u32 regaddr,
 	mps->irq = irq;
 
 	if (pdata == NULL) {
-		dev_err(dev, "probe called without platform data, no "
-			"cs_control function will be called\n");
-		mps->cs_control = NULL;
 		mps->sysclk = 0;
 		master->bus_num = bus_num;
-		master->num_chipselect = 255;
+		if (use_internal_cs) {
+			mps->cs_control = NULL;
+			master->num_chipselect = 1;
+		} else {
+			mps->cs_control = mpc512x_spi_cs_control;
+		}
 	} else {
 		mps->cs_control = pdata->cs_control;
 		mps->sysclk = pdata->sysclk;
@@ -438,6 +477,28 @@ static int mpc512x_psc_spi_do_probe(struct device *dev, u32 regaddr,
 		master->num_chipselect = pdata->max_chipselect;
 	}
 
+	if (!pdata && !use_internal_cs) {
+		for (i = 0; i < num_cs; i++) {
+			int cs_gpio = of_get_named_gpio(dev->of_node,
+							"cs-gpios", i);
+
+			dev_dbg(dev, "cs %d: gpio %d\n", i, cs_gpio);
+			mps->chipselects[i] = cs_gpio;
+			if (!gpio_is_valid(cs_gpio))
+				continue;
+
+			max_cs_num = max(max_cs_num, cs_gpio);
+			ret = gpio_request(mps->chipselects[i],
+					   "psc-spi cs");
+			if (ret) {
+				dev_err(dev, "can't get CS gpio: %d\n", ret);
+				goto free_cs_gpios;
+			}
+		}
+		master->num_chipselect = max_cs_num;
+		mps->num_cs = num_cs;
+	}
+
 	master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH | SPI_LSB_FIRST;
 	master->setup = mpc512x_psc_spi_setup;
 	master->transfer = mpc512x_psc_spi_transfer;
@@ -485,6 +546,11 @@ unreg_master:
 	destroy_workqueue(mps->workqueue);
 free_irq:
 	free_irq(mps->irq, mps);
+free_cs_gpios:
+	while (--i >= 0) {
+		if (gpio_is_valid(mps->chipselects[i]))
+			gpio_free(mps->chipselects[i]);
+	}
 free_master:
 	if (mps->psc)
 		iounmap(mps->psc);
@@ -497,6 +563,7 @@ static int mpc512x_psc_spi_do_remove(struct device *dev)
 {
 	struct spi_master *master = spi_master_get(dev_get_drvdata(dev));
 	struct mpc512x_psc_spi *mps = spi_master_get_devdata(master);
+	int i;
 
 	flush_workqueue(mps->workqueue);
 	destroy_workqueue(mps->workqueue);
@@ -504,6 +571,9 @@ static int mpc512x_psc_spi_do_remove(struct device *dev)
 	free_irq(mps->irq, mps);
 	if (mps->psc)
 		iounmap(mps->psc);
+	for (i = 0; i < mps->num_cs; i++)
+		if (gpio_is_valid(mps->chipselects[i]))
+			gpio_free(mps->chipselects[i]);
 	spi_master_put(master);
 
 	return 0;
-- 
1.7.5.4


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