spi: mediatek: single device does not require cs_gpios

When only one device is present, it is not necessary to specify
cs_gpios, as the CS line can be controlled by the hardware
module.

Without this patch, older device tree bindings used before
37457607 "spi: mediatek: mt8173 spi multiple devices support"
would cause a panic on boot. This fixes the crash, and
re-introduces backward compatibility.

Signed-off-by: Nicolas Boichat <drinkcat@chromium.org>
Acked-by: Leilk Liu <leilk.liu@mediatek.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

1 files changed, 18 insertions, 8 deletions

diff --git a/drivers/spi/spi-mt65xx.c b/drivers/spi/spi-mt65xx.c
index 563954a61424..7840067062a8 100644
--- a/drivers/spi/spi-mt65xx.c
+++ b/drivers/spi/spi-mt65xx.c
@@ -410,7 +410,7 @@ static int mtk_spi_setup(struct spi_device *spi)
         if (!spi->controller_data)
                 spi->controller_data = (void *)&mtk_default_chip_info;
 
-        if (mdata->dev_comp->need_pad_sel)
+        if (mdata->dev_comp->need_pad_sel && gpio_is_valid(spi->cs_gpio))
                 gpio_direction_output(spi->cs_gpio, !(spi->mode & SPI_CS_HIGH));
 
         return 0;
@@ -632,13 +632,23 @@ static int mtk_spi_probe(struct platform_device *pdev)
                         goto err_put_master;
                 }
 
-                for (i = 0; i < master->num_chipselect; i++) {
-                        ret = devm_gpio_request(&pdev->dev, master->cs_gpios[i],
-                                                dev_name(&pdev->dev));
-                        if (ret) {
-                                dev_err(&pdev->dev,
-                                        "can't get CS GPIO %i\n", i);
-                                goto err_put_master;
+                if (!master->cs_gpios && master->num_chipselect > 1) {
+                        dev_err(&pdev->dev,
+                                "cs_gpios not specified and num_chipselect > 1\n");
+                        ret = -EINVAL;
+                        goto err_put_master;
+                }
+
+                if (master->cs_gpios) {
+                        for (i = 0; i < master->num_chipselect; i++) {
+                                ret = devm_gpio_request(&pdev->dev,
+                                                        master->cs_gpios[i],
+                                                        dev_name(&pdev->dev));
+                                if (ret) {
+                                        dev_err(&pdev->dev,
+                                                "can't get CS GPIO %i\n", i);
+                                        goto err_put_master;
+                                }
                         }
                 }
         }