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>

diff --git a/drivers/spi/spi-mt65xx.c b/drivers/spi/spi-mt65xx.c
index 563954a614242718bd125f16f9a3549f783346b8..7840067062a8daf950f4de9a07e232f1482c9485 100644 (file)
--- 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;
+                               }
                        }
                }
        }