[PATCH 5/5] ACPI / gpio: Allow holes in list of GPIOs for a device

Mika Westerberg
2016-09-23T14:57:58Z

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_fixed_args()
instead. In addition we make acpi_gpio_package_count() to handle holes as
well (this matches the DT version).

Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
---
Documentation/acpi/gpio-properties.txt | 15 +++++++++++++++
drivers/gpio/gpiolib-acpi.c | 32 +++++++++++++++++++++-----------
2 files changed, 36 insertions(+), 11 deletions(-)

diff --git a/Documentation/acpi/gpio-properties.txt b/Documentation/acpi/gpio-properties.txt
index 46df91c3512b..2ccb70893122 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
+ }
+ }
+
Other supported properties
--------------------------

diff --git a/drivers/gpio/gpiolib-acpi.c b/drivers/gpio/gpiolib-acpi.c
index 4e50f8f5d597..65c457b9541c 100644
--- a/drivers/gpio/gpiolib-acpi.c
+++ b/drivers/gpio/gpiolib-acpi.c
@@ -467,7 +467,8 @@ static int acpi_gpio_property_lookup(struct fwnode_handle *fwnode,
int ret;

memset(&args, 0, sizeof(args));
- ret = acpi_node_get_property_reference(fwnode, propname, index, &args);
+ ret = acpi_node_get_property_reference_fixed_args(fwnode, propname,
+ index, 3, &args);
if (ret) {
struct acpi_device *adev = to_acpi_device_node(fwnode);

@@ -482,13 +483,13 @@ static int acpi_gpio_property_lookup(struct fwnode_handle *fwnode,
* on returned args.
*/
lookup->adev = args.adev;
- if (args.nargs >= 2) {
- lookup->index = args.args[0];
- lookup->pin_index = args.args[1];
- /* 3rd argument, if present is used to specify active_low. */
- if (args.nargs >= 3)
- lookup->active_low = !!args.args[2];
- }
+ if (args.nargs != 3)
+ return -EPROTO;
+
+ lookup->index = args.args[0];
+ lookup->pin_index = args.args[1];
+ lookup->active_low = !!args.args[2];
+
return 0;
}

@@ -979,18 +980,27 @@ void acpi_gpiochip_remove(struct gpio_chip *chip)
kfree(acpi_gpio);
}

-static unsigned int acpi_gpio_package_count(const union acpi_object *obj)
+static int acpi_gpio_package_count(const union acpi_object *obj)
{
const union acpi_object *element = obj->package.elements;
const union acpi_object *end = element + obj->package.count;
unsigned int count = 0;

while (element < end) {
- if (element->type == ACPI_TYPE_LOCAL_REFERENCE)
+ switch (element->type) {
+ case ACPI_TYPE_LOCAL_REFERENCE:
+ element += 3;
+ /* Fallthrough */
+ case ACPI_TYPE_INTEGER:
+ element++;
count++;
+ break;

- element++;
+ default:
+ return -EPROTO;
+ }
}
+
return count;
}

--
2.9.3