spi: atmel: use managed resource for gpio chip select

Use the managed gpio CS pin request so that we avoid having trouble
in the cleanup code.
In fact, if module was configured with DT, cleanup code released
invalid pin.  Since resource wasn't freed, module cannot be reinserted.

This require to extract the gpio request call from the "setup" function
and call it in the appropriate probe function.

Reported-by: Alexander Morozov <linux@meltdown.ru>
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

Author: Nicolas Ferre

drivers/spi/spi-atmel.c

@@ -24,6 +24,7 @@
 
 #include <linux/io.h>
 #include <linux/gpio.h>
+#include <linux/of_gpio.h>
 #include <linux/pinctrl/consumer.h>
 #include <linux/pm_runtime.h>
 
@@ -1204,7 +1205,6 @@ static int atmel_spi_setup(struct spi_device *spi)
 	u32			csr;
 	unsigned int		bits = spi->bits_per_word;
 	unsigned int		npcs_pin;
-	int			ret;
 
 	as = spi_master_get_devdata(spi->master);
 
@@ -1247,16 +1247,9 @@ static int atmel_spi_setup(struct spi_device *spi)
 		if (!asd)
 			return -ENOMEM;
 
-		if (as->use_cs_gpios) {
-			ret = gpio_request(npcs_pin, dev_name(&spi->dev));
-			if (ret) {
-				kfree(asd);
-				return ret;
-			}
-
+		if (as->use_cs_gpios)
 			gpio_direction_output(npcs_pin,
 					      !(spi->mode & SPI_CS_HIGH));
-		}
 
 		asd->npcs_pin = npcs_pin;
 		spi->controller_state = asd;
@@ -1471,13 +1464,11 @@ static int atmel_spi_transfer_one_message(struct spi_master *master,
 static void atmel_spi_cleanup(struct spi_device *spi)
 {
 	struct atmel_spi_device	*asd = spi->controller_state;
-	unsigned		gpio = (unsigned long) spi->controller_data;
 
 	if (!asd)
 		return;
 
 	spi->controller_state = NULL;
-	gpio_free(gpio);
 	kfree(asd);
 }
 
@@ -1499,6 +1490,39 @@ static void atmel_get_caps(struct atmel_spi *as)
 }
 
 /*-------------------------------------------------------------------------*/
+static int atmel_spi_gpio_cs(struct platform_device *pdev)
+{
+	struct spi_master	*master = platform_get_drvdata(pdev);
+	struct atmel_spi	*as = spi_master_get_devdata(master);
+	struct device_node	*np = master->dev.of_node;
+	int			i;
+	int			ret = 0;
+	int			nb = 0;
+
+	if (!as->use_cs_gpios)
+		return 0;
+
+	if (!np)
+		return 0;
+
+	nb = of_gpio_named_count(np, "cs-gpios");
+	for (i = 0; i < nb; i++) {
+		int cs_gpio = of_get_named_gpio(pdev->dev.of_node,
+						"cs-gpios", i);
+
+			if (cs_gpio == -EPROBE_DEFER)
+				return cs_gpio;
+
+			if (gpio_is_valid(cs_gpio)) {
+				ret = devm_gpio_request(&pdev->dev, cs_gpio,
+							dev_name(&pdev->dev));
+				if (ret)
+					return ret;
+			}
+	}
+
+	return 0;
+}
 
 static int atmel_spi_probe(struct platform_device *pdev)
 {
@@ -1577,6 +1601,10 @@ static int atmel_spi_probe(struct platform_device *pdev)
 		master->num_chipselect = 4;
 	}
 
+	ret = atmel_spi_gpio_cs(pdev);
+	if (ret)
+		goto out_unmap_regs;
+
 	as->use_dma = false;
 	as->use_pdc = false;
 	if (as->caps.has_dma_support) {