From 6f7194a10bdba1588357342c6daaaeef98e0004f Mon Sep 17 00:00:00 2001 From: Mika Westerberg Date: Fri, 21 Oct 2016 17:21:29 +0300 Subject: ACPI / gpio: Allow holes in list of GPIOs for a device Make it possible to have an empty GPIOs in a GPIO list for device. For example a SPI master may use both GPIOs and native pins as chip selects and we need to be able to distinguish between the two. This makes it mandatory to have exactly 3 arguments for GPIOs and then converts gpiolib to use of __acpi_node_get_property_reference() instead. In addition we make acpi_gpio_package_count() to handle holes as well (this matches the DT version). Signed-off-by: Mika Westerberg Acked-by: Rafael J. Wysocki Signed-off-by: Linus Walleij --- Documentation/acpi/gpio-properties.txt | 15 +++++++++++++++ 1 file changed, 15 insertions(+) (limited to 'Documentation/acpi/gpio-properties.txt') diff --git a/Documentation/acpi/gpio-properties.txt b/Documentation/acpi/gpio-properties.txt index 5aafe0b351a1..09cff657b82c 100644 --- a/Documentation/acpi/gpio-properties.txt +++ b/Documentation/acpi/gpio-properties.txt @@ -51,6 +51,21 @@ it to 1 marks the GPIO as active low. In our Bluetooth example the "reset-gpios" refers to the second GpioIo() resource, second pin in that resource with the GPIO number of 31. +It is possible to leave holes in the array of GPIOs. This is useful in +cases like with SPI host controllers where some chip selects may be +implemented as GPIOs and some as native signals. For example a SPI host +controller can have chip selects 0 and 2 implemented as GPIOs and 1 as +native: + + Package () { + "cs-gpios", + Package () { + ^GPIO, 19, 0, 0, // chip select 0: GPIO + 0, // chip select 1: native signal + ^GPIO, 20, 0, 0, // chip select 2: GPIO + } + } + ACPI GPIO Mappings Provided by Drivers -------------------------------------- -- cgit