From: Michael Polyntsov <michael.polynt...@iopsys.eu>
Some boards don't have chipselect lines for leds so cs-gpios is not
specified in the dts leading to probing error. Fix it by making
behavior similar to the one in Linux, parse num-chipselects and
if it is zero, ignore cs-gpios.
Signed-off-by: Michael Polyntsov <michael.polynt...@iopsys.eu>
Signed-off-by: Mikhail Kshevetskiy <mikhail.kshevets...@iopsys.eu>
---
doc/device-tree-bindings/spi/soft-spi.txt | 5 +++--
drivers/spi/soft_spi.c | 22 +++++++++++++++++++++-
2 files changed, 24 insertions(+), 3 deletions(-)
diff --git a/doc/device-tree-bindings/spi/soft-spi.txt
b/doc/device-tree-bindings/spi/soft-spi.txt
index bdf7e86befb..77b01b2fd9a 100644
--- a/doc/device-tree-bindings/spi/soft-spi.txt
+++ b/doc/device-tree-bindings/spi/soft-spi.txt
@@ -8,14 +8,15 @@ The soft SPI node requires the following properties:
Mandatory properties:
compatible: "spi-gpio"
-cs-gpios: GPIOs to use for SPI chip select (output)
+cs-gpios: GPIOs to use for SPI chip select (output), not required if
num-chipselects = <0>
sck-gpios: GPIO to use for SPI clock (output)
And at least one of:
mosi-gpios: GPIO to use for SPI MOSI line (output)
miso-gpios: GPIO to use for SPI MISO line (input)
-Optional propertie:
+Optional properties:
spi-delay-us: Number of microseconds of delay between each CS transition
+num-chipselects: Number of chipselect lines
The GPIOs should be specified as required by the GPIO controller referenced.
The first cell holds the phandle of the controller and the second cell
diff --git a/drivers/spi/soft_spi.c b/drivers/spi/soft_spi.c
index 3fe62818a44..2e80b7bb08e 100644
--- a/drivers/spi/soft_spi.c
+++ b/drivers/spi/soft_spi.c
@@ -238,6 +238,18 @@ static int soft_spi_of_to_plat(struct udevice *dev)
return 0;
}
+static int retrieve_num_chipselects(struct udevice *dev)
+{
+ int chipselects;
+ int ret;
+
+ ret = ofnode_read_u32(dev_ofnode(dev), "num-chipselects", &chipselects);
+ if (ret)
+ return ret;
+
+ return chipselects;
+}
+
static int soft_spi_probe(struct udevice *dev)
{
struct spi_slave *slave = dev_get_parent_priv(dev);
@@ -250,7 +262,15 @@ static int soft_spi_probe(struct udevice *dev)
ret = gpio_request_by_name(dev, "cs-gpios", 0, &plat->cs,
GPIOD_IS_OUT | cs_flags);
- if (ret)
+ /*
+ * If num-chipselects is zero we're ignoring absence of cs-gpios. This
+ * code relies on the fact that `gpio_request_by_name` call above
+ * initiailizes plat->cs to correct value with invalid GPIO even when
+ * there is no cs-gpios node in dts. All other functions which work
+ * with plat->cs verify it via `dm_gpio_is_valid` before using it, so
+ * such value doesn't cause any problems.
+ */
+ if (ret && retrieve_num_chipselects(dev) != 0)
return -EINVAL;
ret = gpio_request_by_name(dev, "gpio-sck", 0, &plat->sclk,
--
2.43.0
