From 9d50f95bc0d5df56f2591b950a251d90bffad094 Mon Sep 17 00:00:00 2001 From: Charles Keepax Date: Tue, 16 Apr 2024 11:09:01 +0100 Subject: gpio: swnode: Add ability to specify native chip selects for SPI SPI devices can specify a cs-gpios property to enumerate their chip selects. Under device tree, a zero entry in this property can be used to specify that a particular chip select is using the SPI controllers native chip select, for example: cs-gpios = <&gpio1 0 0>, <0>; Here, the second chip select is native. However, when using swnodes there is currently no way to specify a native chip select. The proposal here is to register a swnode_gpio_undefined software node, that can be specified to allow the indication of a native chip select. For example: static const struct software_node_ref_args device_cs_refs[] = { { .node = &device_gpiochip_swnode, .nargs = 2, .args = { 0, GPIO_ACTIVE_LOW }, }, { .node = &swnode_gpio_undefined, .nargs = 0, }, }; Register the swnode as the gpiolib is initialised and check in swnode_get_gpio_device() if the returned node matches swnode_gpio_undefined and return -ENOENT, which matches the behaviour of the device tree system when it encounters a 0 phandle. Reviewed-by: Linus Walleij Reviewed-by: Andy Shevchenko Signed-off-by: Charles Keepax Link: https://lore.kernel.org/r/20240416100904.3738093-2-ckeepax@opensource.cirrus.com Signed-off-by: Mark Brown --- include/linux/gpio/property.h | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'include/linux/gpio/property.h') diff --git a/include/linux/gpio/property.h b/include/linux/gpio/property.h index 6c75c8bd44a0..832a60c2e0b9 100644 --- a/include/linux/gpio/property.h +++ b/include/linux/gpio/property.h @@ -5,7 +5,11 @@ #include /* for GPIO_* flags */ #include +struct software_node; + #define PROPERTY_ENTRY_GPIO(_name_, _chip_node_, _idx_, _flags_) \ PROPERTY_ENTRY_REF(_name_, _chip_node_, _idx_, _flags_) +extern const struct software_node swnode_gpio_undefined; + #endif /* __LINUX_GPIO_PROPERTY_H */ -- cgit v1.2.3