linux-kernel - [PATCH] spi: sun6i: Add support for GPIO chip select lines

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Date:   Tue,  5 May 2020 18:41:35 -0700
From:   Alistair Francis <alistair@...stair23.me>
To:     broonie@...nel.org, linux-spi@...r.kernel.org
Cc:     mripard@...nel.org, wens@...e.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        alistair23@...il.com, Alistair Francis <alistair@...stair23.me>
Subject: [PATCH] spi: sun6i: Add support for GPIO chip select lines

Add a setup function that can be used to support using generic GPIO
lines for the chip select.

Signed-off-by: Alistair Francis <alistair@...stair23.me>
---
 drivers/spi/spi-sun6i.c | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)

diff --git a/drivers/spi/spi-sun6i.c b/drivers/spi/spi-sun6i.c
index ec7967be9e2f..fd4e19434942 100644
--- a/drivers/spi/spi-sun6i.c
+++ b/drivers/spi/spi-sun6i.c
@@ -10,6 +10,7 @@
 #include <linux/clk.h>
 #include <linux/delay.h>
 #include <linux/device.h>
+#include <linux/gpio.h>
 #include <linux/interrupt.h>
 #include <linux/io.h>
 #include <linux/module.h>
@@ -171,6 +172,31 @@ static inline void sun6i_spi_fill_fifo(struct sun6i_spi *sspi, int len)
 	}
 }
 
+static int sun6i_spi_setup(struct spi_device *spi)
+{
+	int ret;
+
+	/* sanity check for native cs */
+	if (spi->mode & SPI_NO_CS)
+		return 0;
+	if (gpio_is_valid(spi->cs_gpio)) {
+		/* with gpio-cs set the GPIO to the correct level
+		 * and as output (in case the dt has the gpio not configured
+		 * as output but native cs)
+		 */
+		ret = gpio_direction_output(spi->cs_gpio,
+					    (spi->mode & SPI_CS_HIGH) ? 0 : 1);
+		if (ret)
+			dev_err(&spi->dev,
+				"could not set gpio %i as output: %i\n",
+				spi->cs_gpio, ret);
+
+		return ret;
+	}
+
+	return 0;
+}
+
 static void sun6i_spi_set_cs(struct spi_device *spi, bool enable)
 {
 	struct sun6i_spi *sspi = spi_master_get_devdata(spi->master);
@@ -470,6 +496,7 @@ static int sun6i_spi_probe(struct platform_device *pdev)
 
 	master->max_speed_hz = 100 * 1000 * 1000;
 	master->min_speed_hz = 3 * 1000;
+	master->setup = sun6i_spi_setup;
 	master->set_cs = sun6i_spi_set_cs;
 	master->transfer_one = sun6i_spi_transfer_one;
 	master->num_chipselect = 4;
-- 
2.26.2