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 <lkund...@v3.sk>
Tested-by: Pavel Machek <pa...@ucw.cz>
---
Changes since v2
- Avoid an useless delay if there's no ready GPIO
- Remove useless (int)PTR_ERR(...) casts from pxa2xx_spi_probe()
(thanks to Geert Uytterhoeven)
drivers/spi/spi-pxa2xx.c | 16 +++++++++++++++-
drivers/spi/spi-pxa2xx.h | 3 +++
2 files changed, 18 insertions(+), 1 deletion(-)
diff --git a/drivers/spi/spi-pxa2xx.c b/drivers/spi/spi-pxa2xx.c
index 54ae77f1227c..7e5aab0af501 100644
--- 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 513c53aaeab2..4e324da66ef7 100644
--- 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 {
--
2.19.1
