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

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Message-Id: <1452211907-16074-1-git-send-email-mans@mansr.com>
Date:	Fri,  8 Jan 2016 00:11:47 +0000
From:	Mans Rullgard <mans@...sr.com>
To:	Nicolas Ferre <nicolas.ferre@...el.com>,
	Mark Brown <broonie@...nel.org>, linux-spi@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH] spi: atmel: improve internal vs gpio chip-select choice

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@...sr.com>
---
 drivers/spi/spi-atmel.c | 44 ++++++++++++++++++++++----------------------
 1 file changed, 22 insertions(+), 22 deletions(-)

diff --git a/drivers/spi/spi-atmel.c b/drivers/spi/spi-atmel.c
index aebad36391c9..8be07fb67d4d 100644
--- a/drivers/spi/spi-atmel.c
+++ b/drivers/spi/spi-atmel.c
@@ -310,7 +310,6 @@ struct atmel_spi {
 
 	bool			use_dma;
 	bool			use_pdc;
-	bool			use_cs_gpios;
 	/* dmaengine data */
 	struct atmel_spi_dma	dma;
 
@@ -324,6 +323,7 @@ struct atmel_spi {
 struct atmel_spi_device {
 	unsigned int		npcs_pin;
 	u32			csr;
+	bool			use_cs_gpio;
 };
 
 #define BUFFER_SIZE		PAGE_SIZE
@@ -388,7 +388,7 @@ 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;
@@ -405,7 +405,7 @@ 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);
 	}
@@ -434,7 +434,7 @@ 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);
@@ -1221,8 +1221,6 @@ 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.
 	 *
@@ -1233,21 +1231,28 @@ 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))
-		npcs_pin = spi->cs_gpio;
-
 	asd = spi->controller_state;
 	if (!asd) {
 		asd = kzalloc(sizeof(struct atmel_spi_device), GFP_KERNEL);
 		if (!asd)
 			return -ENOMEM;
 
-		if (as->use_cs_gpios) {
+		npcs_pin = (unsigned long)spi->controller_data;
+
+		if (gpio_is_valid(spi->cs_gpio)) {
+			/* GPIO from DT */
+			npcs_pin = spi->cs_gpio;
+			asd->use_cs_gpio = true;
+		} else if (npcs_pin && gpio_is_valid(npcs_pin)) {
+			/* GPIO from platform data */
+			asd->use_cs_gpio = true;
+		} else {
+			/* internal chip-select */
+			npcs_pin = spi->chip_select;
+			asd->use_cs_gpio = false;
+		}
+
+		if (asd->use_cs_gpio) {
 			ret = gpio_request(npcs_pin, dev_name(&spi->dev));
 			if (ret) {
 				kfree(asd);
@@ -1262,6 +1267,8 @@ static int atmel_spi_setup(struct spi_device *spi)
 		spi->controller_state = asd;
 	}
 
+	if (!asd->use_cs_gpio)
+		csr |= SPI_BIT(CSAAT);
 	asd->csr = csr;
 
 	dev_dbg(&spi->dev,
@@ -1569,13 +1576,6 @@ 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;
-		master->num_chipselect = 4;
-	}
-
 	as->use_dma = false;
 	as->use_pdc = false;
 	if (as->caps.has_dma_support) {
-- 
2.7.0