spi: pxa2xx: Add ready signal

Strobe a GPIO line when the slave TX FIFO is filled. This is how the
Embedded Controller on an OLPC XO-1.75 machine, that happens to be a SPI
master, learns that it can initiate a transaction.

Signed-off-by: Lubomir Rintel <lkundrak@v3.sk>
Tested-by: Pavel Machek <pavel@ucw.cz>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Mark Brown <broonie@kernel.org>

diff --git a/drivers/spi/spi-pxa2xx.c b/drivers/spi/spi-pxa2xx.c
index a057c3b..69b221e 100644 (file)
--- a/drivers/spi/spi-pxa2xx.c
+++ b/drivers/spi/spi-pxa2xx.c
@@ -1081,6 +1081,11 @@ static int pxa2xx_spi_transfer_one(struct spi_controller *master,
        if (spi_controller_is_slave(master)) {
                while (drv_data->write(drv_data))
                        ;
+               if (drv_data->gpiod_ready) {
+                       gpiod_set_value(drv_data->gpiod_ready, 1);
+                       udelay(1);
+                       gpiod_set_value(drv_data->gpiod_ready, 0);
+               }
        }
 
        /*
@@ -1778,7 +1783,7 @@ static int pxa2xx_spi_probe(struct platform_device *pdev)
                                if (PTR_ERR(gpiod) == -ENOENT)
                                        continue;
 
-                               status = (int)PTR_ERR(gpiod);
+                               status = PTR_ERR(gpiod);
                                goto out_error_clock_enabled;
                        } else {
                                drv_data->cs_gpiods[i] = gpiod;
@@ -1786,6 +1791,15 @@ static int pxa2xx_spi_probe(struct platform_device *pdev)
                }
        }
 
+       if (platform_info->is_slave) {
+               drv_data->gpiod_ready = devm_gpiod_get_optional(dev,
+                                               "ready", GPIOD_OUT_LOW);
+               if (IS_ERR(drv_data->gpiod_ready)) {
+                       status = PTR_ERR(drv_data->gpiod_ready);
+                       goto out_error_clock_enabled;
+               }
+       }
+
        pm_runtime_set_autosuspend_delay(&pdev->dev, 50);
        pm_runtime_use_autosuspend(&pdev->dev);
        pm_runtime_set_active(&pdev->dev);

diff --git a/drivers/spi/spi-pxa2xx.h b/drivers/spi/spi-pxa2xx.h
index 513c53a..4e324da 100644 (file)
--- a/drivers/spi/spi-pxa2xx.h
+++ b/drivers/spi/spi-pxa2xx.h
@@ -64,6 +64,9 @@ struct driver_data {
 
        /* GPIOs for chip selects */
        struct gpio_desc **cs_gpiods;
+
+       /* Optional slave FIFO ready signal */
+       struct gpio_desc *gpiod_ready;
 };
 
 struct chip_data {