[PATCH v2] spi: atmel: improve internal vs gpio chip-select choice

[Mans Rullgard]

The driver currently chooses between internal chip-select or gpio
based on the existence of the cs-gpios DT property which fails on
non-DT systems and also enforces the same choice for all devices.

This patch makes the method per device instead of per controller
and fixes the selection on non-DT systems.  With these changes,
the chip-select method for each device is chosen according to the
following priority:

1. GPIO from device tree
2. GPIO from platform data
3. Internal chip-select

Tested on AVR32 ATSTK1000.

Signed-off-by: Mans Rullgard <mans at mansr.com>
---
Changes:
- allow internal CS only hardware v2
- retain seting of master->num_chipselect to 4 on hardware v2 if
  cs-gpios property is missing
---
 drivers/spi/spi-atmel.c | 38 +++++++++++++++++++++++---------------
 1 file changed, 23 insertions(+), 15 deletions(-)

diff --git a/drivers/spi/spi-atmel.c b/drivers/spi/spi-atmel.c
index 08cbb3e43c76..d4a806e24060 100644
--- a/drivers/spi/spi-atmel.c
+++ b/drivers/spi/spi-atmel.c
@@ -312,7 +312,6 @@ struct atmel_spi {
 
 	bool			use_dma;
 	bool			use_pdc;
-	bool			use_cs_gpios;
 	/* dmaengine data */
 	struct atmel_spi_dma	dma;
 
@@ -323,6 +322,7 @@ struct atmel_spi {
 struct atmel_spi_device {
 	unsigned int		npcs_pin;
 	u32			csr;
+	bool			use_cs_gpio;
 };
 
 #define BUFFER_SIZE		PAGE_SIZE
@@ -387,7 +387,7 @@ static void cs_activate(struct atmel_spi *as, struct spi_device *spi)
 		}
 
 		mr = spi_readl(as, MR);
-		if (as->use_cs_gpios)
+		if (asd->use_cs_gpio)
 			gpio_set_value(asd->npcs_pin, active);
 	} else {
 		u32 cpol = (spi->mode & SPI_CPOL) ? SPI_BIT(CPOL) : 0;
@@ -404,7 +404,7 @@ static void cs_activate(struct atmel_spi *as, struct spi_device *spi)
 
 		mr = spi_readl(as, MR);
 		mr = SPI_BFINS(PCS, ~(1 << spi->chip_select), mr);
-		if (as->use_cs_gpios && spi->chip_select != 0)
+		if (asd->use_cs_gpio && spi->chip_select != 0)
 			gpio_set_value(asd->npcs_pin, active);
 		spi_writel(as, MR, mr);
 	}
@@ -433,7 +433,7 @@ static void cs_deactivate(struct atmel_spi *as, struct spi_device *spi)
 			asd->npcs_pin, active ? " (low)" : "",
 			mr);
 
-	if (!as->use_cs_gpios)
+	if (!asd->use_cs_gpio)
 		spi_writel(as, CR, SPI_BIT(LASTXFER));
 	else if (atmel_spi_is_v2(as) || spi->chip_select != 0)
 		gpio_set_value(asd->npcs_pin, !active);
@@ -1539,6 +1539,7 @@ static int atmel_spi_setup(struct spi_device *spi)
 	unsigned int		bits = spi->bits_per_word;
 	unsigned int		npcs_pin;
 	int			ret;
+	bool			use_cs_gpio;
 
 	as = spi_master_get_devdata(spi->master);
 
@@ -1565,8 +1566,6 @@ static int atmel_spi_setup(struct spi_device *spi)
 		csr |= SPI_BIT(CPOL);
 	if (!(spi->mode & SPI_CPHA))
 		csr |= SPI_BIT(NCPHA);
-	if (!as->use_cs_gpios)
-		csr |= SPI_BIT(CSAAT);
 
 	/* DLYBS is mostly irrelevant since we manage chipselect using GPIOs.
 	 *
@@ -1577,13 +1576,22 @@ static int atmel_spi_setup(struct spi_device *spi)
 	csr |= SPI_BF(DLYBS, 0);
 	csr |= SPI_BF(DLYBCT, 0);
 
-	/* chipselect must have been muxed as GPIO (e.g. in board setup) */
 	npcs_pin = (unsigned long)spi->controller_data;
 
-	if (!as->use_cs_gpios)
-		npcs_pin = spi->chip_select;
-	else if (gpio_is_valid(spi->cs_gpio))
+	if (gpio_is_valid(spi->cs_gpio)) {
+		/* GPIO from DT */
 		npcs_pin = spi->cs_gpio;
+		use_cs_gpio = true;
+	} else if (npcs_pin && gpio_is_valid(npcs_pin)) {
+		/* GPIO from platform data */
+		use_cs_gpio = true;
+	} else if (atmel_spi_is_v2(as)) {
+		/* internal chip-select */
+		npcs_pin = spi->chip_select;
+		use_cs_gpio = false;
+	} else {
+		return -EINVAL;
+	}
 
 	asd = spi->controller_state;
 	if (!asd) {
@@ -1591,7 +1599,7 @@ static int atmel_spi_setup(struct spi_device *spi)
 		if (!asd)
 			return -ENOMEM;
 
-		if (as->use_cs_gpios) {
+		if (use_cs_gpio) {
 			ret = gpio_request(npcs_pin, dev_name(&spi->dev));
 			if (ret) {
 				kfree(asd);
@@ -1603,6 +1611,7 @@ static int atmel_spi_setup(struct spi_device *spi)
 		}
 
 		asd->npcs_pin = npcs_pin;
+		asd->use_cs_gpio = use_cs_gpio;
 		spi->controller_state = asd;
 	} else {
 		atmel_spi_lock(as);
@@ -1612,6 +1621,8 @@ static int atmel_spi_setup(struct spi_device *spi)
 		atmel_spi_unlock(as);
 	}
 
+	if (!asd->use_cs_gpio)
+		csr |= SPI_BIT(CSAAT);
 	asd->csr = csr;
 
 	dev_dbg(&spi->dev,
@@ -1807,12 +1818,9 @@ static int atmel_spi_probe(struct platform_device *pdev)
 
 	atmel_get_caps(as);
 
-	as->use_cs_gpios = true;
 	if (atmel_spi_is_v2(as) &&
-	    !of_get_property(pdev->dev.of_node, "cs-gpios", NULL)) {
-		as->use_cs_gpios = false;
+	    !of_get_property(pdev->dev.of_node, "cs-gpios", NULL))
 		master->num_chipselect = 4;
-	}
 
 	as->use_dma = false;
 	as->use_pdc = false;
-- 
2.7.0