diff mbox

[RFC,2/2] spi: pxa2xx: Only claim CS GPIOs when the slave device is created

Message ID 5a691263ccf9d61134d6184861b37eaf37b13b77.1501760433.git.jan.kiszka@siemens.com (mailing list archive)
State New, archived
Headers show

Commit Message

Jan Kiszka Aug. 3, 2017, 11:40 a.m. UTC 
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 | 68 +++++++++++++++++++++---------------------------
 drivers/spi/spi-pxa2xx.h |  3 +--
 2 files changed, 31 insertions(+), 40 deletions(-)

Comments

Mika Westerberg Aug. 4, 2017, 10:29 a.m. UTC | #1 
On Thu, Aug 03, 2017 at 01:40:33PM +0200, Jan Kiszka wrote:
> 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>

Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>
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Mark Brown Aug. 4, 2017, 11:43 a.m. UTC | #2 
On Thu, Aug 03, 2017 at 01:40:33PM +0200, Jan Kiszka wrote:
> 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.

This doesn't apply against current code, please check and resend.
diff mbox

Patch

diff --git a/drivers/spi/spi-pxa2xx.c b/drivers/spi/spi-pxa2xx.c
index 7faba738110c..577a2f4ba3bf 100644
--- a/drivers/spi/spi-pxa2xx.c
+++ b/drivers/spi/spi-pxa2xx.c
@@ -1213,19 +1213,34 @@  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;
 
 	if (chip == NULL)
 		return 0;
 
-	if (drv_data->cs_gpiods) {
-		gpiod = drv_data->cs_gpiods[spi->chip_select];
-		if (gpiod) {
-			chip->gpiod_cs = gpiod;
-			chip->gpio_cs_inverted = spi->mode & SPI_CS_HIGH;
-			gpiod_set_value(gpiod, chip->gpio_cs_inverted);
+	if (drv_data->cs_count > 0) {
+		/* setup() might be called multiple times. */
+		if (chip->gpiod_cs)
+			return 0;
+
+		if (spi->chip_select >= drv_data->cs_count)
+			return -EINVAL;
+
+		chip->gpio_cs_inverted = spi->mode & SPI_CS_HIGH;
+
+		gpiod = gpiod_get_index(pdev, "cs", spi->chip_select,
+					chip->gpio_cs_inverted ?
+				        GPIOD_OUT_HIGH : GPIOD_OUT_LOW);
+		if (IS_ERR(gpiod)) {
+			/* Means use native chip select */
+			if (PTR_ERR(gpiod) == -ENOENT)
+				return 0;
+
+			return (int)PTR_ERR(gpiod);
 		}
+		chip->gpiod_cs = gpiod;
 
 		return 0;
 	}
@@ -1415,9 +1430,13 @@  static void cleanup(struct spi_device *spi)
 	if (!chip)
 		return;
 
-	if (drv_data->ssp_type != CE4100_SSP && !drv_data->cs_gpiods &&
-	    chip->gpiod_cs)
-		gpio_free(desc_to_gpio(chip->gpiod_cs));
+	if (drv_data->ssp_type != CE4100_SSP && chip->gpiod_cs) {
+		if (drv_data->cs_count > 0)
+			gpiod_put(chip->gpiod_cs);
+		else
+			gpio_free(desc_to_gpio(chip->gpiod_cs));
+		chip->gpiod_cs = NULL;
+	}
 
 	kfree(chip);
 }
@@ -1752,37 +1771,10 @@  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;
-			}
-		}
-	}
+	drv_data->cs_count = count;
 
 	tasklet_init(&drv_data->pump_transfers, pump_transfers,
 		     (unsigned long)drv_data);
diff --git a/drivers/spi/spi-pxa2xx.h b/drivers/spi/spi-pxa2xx.h
index 94f7b0713281..8551c881f636 100644
--- a/drivers/spi/spi-pxa2xx.h
+++ b/drivers/spi/spi-pxa2xx.h
@@ -67,8 +67,7 @@  struct driver_data {
 
 	void __iomem *lpss_base;
 
-	/* GPIOs for chip selects */
-	struct gpio_desc **cs_gpiods;
+	int cs_count;
 };
 
 struct chip_data {