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[PATCH] spi: pxa2xx: Only claim CS GPIOs when the slave device is created

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From: Jan Kiszka <jan.kiszka@siemens.com>

Avoid hogging chip select GPIOs just because they are listed for the
master. They might be mulitplexed and, if no slave device is attached,
used for different purposes. Moreover, this strategy avoids having to
allocate a cs_gpiods structure.

Tested on the IOT2000 where the second SPI bus is connected to an
Arduino-compatible connector and multiplexed between SPI, GPIO and PWM
usage.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
---
 drivers/spi/spi-pxa2xx.c | 59 +++++++++++++++++-------------------------------
 1 file changed, 21 insertions(+), 38 deletions(-)

diff --git a/drivers/spi/spi-pxa2xx.c b/drivers/spi/spi-pxa2xx.c
index 38d053682892..be991266a6ce 100644
--- a/drivers/spi/spi-pxa2xx.c
+++ b/drivers/spi/spi-pxa2xx.c
@@ -1213,21 +1213,33 @@ static int setup_cs(struct spi_device *spi, struct chip_data *chip,
 		    struct pxa2xx_spi_chip *chip_info)
 {
 	struct driver_data *drv_data = spi_master_get_devdata(spi->master);
+	struct device *pdev = &drv_data->pdev->dev;
+	struct gpio_desc *gpiod;
 	int err = 0;
+	int count;
 
 	if (chip == NULL)
 		return 0;
 
-	if (drv_data->cs_gpiods) {
-		struct gpio_desc *gpiod;
+	count = gpiod_count(pdev, "cs");
+	if (count > 0) {
+		if (spi->chip_select >= count)
+			return -EINVAL;
+
+		gpiod = gpiod_get_index(pdev, "cs", spi->chip_select,
+					GPIOD_OUT_HIGH);
+		if (IS_ERR(gpiod)) {
+			/* Means use native chip select */
+			if (PTR_ERR(gpiod) == -ENOENT)
+				return 0;
 
-		gpiod = drv_data->cs_gpiods[spi->chip_select];
-		if (gpiod) {
-			chip->gpio_cs = desc_to_gpio(gpiod);
-			chip->gpio_cs_inverted = spi->mode & SPI_CS_HIGH;
-			gpiod_set_value(gpiod, chip->gpio_cs_inverted);
+			return PTR_ERR(gpiod);
 		}
 
+		chip->gpio_cs = desc_to_gpio(gpiod);
+		chip->gpio_cs_inverted = spi->mode & SPI_CS_HIGH;
+		gpiod_set_value(gpiod, chip->gpio_cs_inverted);
+
 		return 0;
 	}
 
@@ -1415,8 +1427,7 @@ static void cleanup(struct spi_device *spi)
 	if (!chip)
 		return;
 
-	if (drv_data->ssp_type != CE4100_SSP && !drv_data->cs_gpiods &&
-	    gpio_is_valid(chip->gpio_cs))
+	if (drv_data->ssp_type != CE4100_SSP && gpio_is_valid(chip->gpio_cs))
 		gpio_free(chip->gpio_cs);
 
 	kfree(chip);
@@ -1752,38 +1763,10 @@ static int pxa2xx_spi_probe(struct platform_device *pdev)
 	master->num_chipselect = platform_info->num_chipselect;
 
 	count = gpiod_count(&pdev->dev, "cs");
-	if (count > 0) {
-		int i;
-
+	if (count > 0)
 		master->num_chipselect = max_t(int, count,
 			master->num_chipselect);
 
-		drv_data->cs_gpiods = devm_kcalloc(&pdev->dev,
-			master->num_chipselect, sizeof(struct gpio_desc *),
-			GFP_KERNEL);
-		if (!drv_data->cs_gpiods) {
-			status = -ENOMEM;
-			goto out_error_clock_enabled;
-		}
-
-		for (i = 0; i < master->num_chipselect; i++) {
-			struct gpio_desc *gpiod;
-
-			gpiod = devm_gpiod_get_index(dev, "cs", i,
-						     GPIOD_OUT_HIGH);
-			if (IS_ERR(gpiod)) {
-				/* Means use native chip select */
-				if (PTR_ERR(gpiod) == -ENOENT)
-					continue;
-
-				status = (int)PTR_ERR(gpiod);
-				goto out_error_clock_enabled;
-			} else {
-				drv_data->cs_gpiods[i] = gpiod;
-			}
-		}
-	}
-
 	tasklet_init(&drv_data->pump_transfers, pump_transfers,
 		     (unsigned long)drv_data);
 

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[PATCH] spi: pxa2xx: Only claim CS GPIOs when the slave device is  created Jan Kiszka <jan.kiszka@web.de> - 2017-07-08 10:50 +0200
  Re: [PATCH] spi: pxa2xx: Only claim CS GPIOs when the slave device is created Andy Shevchenko <andy.shevchenko@gmail.com> - 2017-07-08 23:50 +0200
    Re: [PATCH] spi: pxa2xx: Only claim CS GPIOs when the slave device is  created Jan Kiszka <jan.kiszka@web.de> - 2017-07-09 11:40 +0200
      Re: [PATCH] spi: pxa2xx: Only claim CS GPIOs when the slave device is created Andy Shevchenko <andy.shevchenko@gmail.com> - 2017-07-09 12:00 +0200
        Re: [PATCH] spi: pxa2xx: Only claim CS GPIOs when the slave device is  created Jan Kiszka <jan.kiszka@web.de> - 2017-07-09 12:40 +0200
    Re: [PATCH] spi: pxa2xx: Only claim CS GPIOs when the slave device  is created Mark Brown <broonie@kernel.org> - 2017-07-10 14:10 +0200
      Re: [PATCH] spi: pxa2xx: Only claim CS GPIOs when the slave device is  created Jan Kiszka <jan.kiszka@web.de> - 2017-07-10 19:40 +0200
  Applied "spi: pxa2xx: Only claim CS GPIOs when the slave device is created" to the spi tree Mark Brown <broonie@kernel.org> - 2017-07-17 18:10 +0200

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