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@xxxxx>
---
drivers/spi/spi-pxa2xx.c | 12 ++++++++++++
drivers/spi/spi-pxa2xx.h | 3 +++
2 files changed, 15 insertions(+)
diff --git a/drivers/spi/spi-pxa2xx.c b/drivers/spi/spi-pxa2xx.c
index 3848842d68fd..a3b4b12c1077 100644
--- a/drivers/spi/spi-pxa2xx.c
+++ b/drivers/spi/spi-pxa2xx.c
@@ -1079,6 +1079,9 @@ static int pxa2xx_spi_transfer_one(struct spi_controller *master,
if (spi_controller_is_slave(master)) {
while (drv_data->write(drv_data))
;
+ gpiod_set_value(drv_data->gpiod_ready, 1);
+ udelay(1);
+ gpiod_set_value(drv_data->gpiod_ready, 0);
}
/*
@@ -1784,6 +1787,15 @@ 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 = (int)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 {
--
2.19.0
