linux-kernel - [PATCH v2 2/4] ACPI / gpio: Add support for naming GPIOs

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Date:   Thu, 29 Sep 2016 16:39:42 +0300
From:   Mika Westerberg <mika.westerberg@...ux.intel.com>
To:     "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Linus Walleij <linus.walleij@...aro.org>
Cc:     Alexandre Courbot <gnurou@...il.com>, linux-acpi@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Mika Westerberg <mika.westerberg@...ux.intel.com>
Subject: [PATCH v2 2/4] ACPI / gpio: Add support for naming GPIOs

DT has property 'gpio-line-names' to name GPIO lines the controller has if
present. Use this very same property in ACPI as well to provide nice names
for the GPIOS.

Signed-off-by: Mika Westerberg <mika.westerberg@...ux.intel.com>
---
 Documentation/acpi/gpio-properties.txt | 21 +++++++++++++++++
 drivers/gpio/gpiolib-acpi.c            | 43 ++++++++++++++++++++++++++++++++++
 2 files changed, 64 insertions(+)

diff --git a/Documentation/acpi/gpio-properties.txt b/Documentation/acpi/gpio-properties.txt
index 5aafe0b351a1..7875974823ae 100644
--- a/Documentation/acpi/gpio-properties.txt
+++ b/Documentation/acpi/gpio-properties.txt
@@ -51,6 +51,27 @@ 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.
 
+Other supported properties
+--------------------------
+
+Following Device Tree compatible device properties are also supported by
+_DSD device properties for GPIO controllers:
+
+- gpio-line-names
+
+Example:
+
+  Package () {
+      "gpio-line-names",
+      Package () {
+          "SPI0_CS_N", "EXP2_INT", "MUX6_IO", "UART0_RXD", "MUX7_IO",
+          "LVL_C_A1", "MUX0_IO", "SPI1_MISO"
+      }
+  }
+
+See Documentation/devicetree/bindings/gpio/gpio.tx for more information
+about these properties.
+
 ACPI GPIO Mappings Provided by Drivers
 --------------------------------------
 
diff --git a/drivers/gpio/gpiolib-acpi.c b/drivers/gpio/gpiolib-acpi.c
index af514618d7fb..202cf1b842de 100644
--- a/drivers/gpio/gpiolib-acpi.c
+++ b/drivers/gpio/gpiolib-acpi.c
@@ -805,6 +805,46 @@ static void acpi_gpiochip_free_regions(struct acpi_gpio_chip *achip)
 	}
 }
 
+static void acpi_gpiochip_set_names(struct acpi_gpio_chip *achip)
+{
+	struct gpio_chip *chip = achip->chip;
+	struct gpio_device *gdev = chip->gpiodev;
+	const char **names;
+	int ret, i;
+
+	ret = device_property_read_string_array(chip->parent, "gpio-line-names",
+						NULL, 0);
+	if (ret < 0)
+		return;
+
+	if (ret != gdev->ngpio) {
+		dev_warn(chip->parent,
+			 "names %d do not match number of GPIOs %d\n", ret,
+			 gdev->ngpio);
+		return;
+	}
+
+	names = kcalloc(gdev->ngpio, sizeof(*names), GFP_KERNEL);
+	if (!names)
+		return;
+
+	ret = device_property_read_string_array(chip->parent, "gpio-line-names",
+						names, gdev->ngpio);
+	if (ret < 0) {
+		dev_warn(chip->parent, "Failed to read GPIO line names\n");
+		return;
+	}
+
+	/*
+	 * It is fine to assign the name, it will be allocated as long as
+	 * the ACPI device exists.
+	 */
+	for (i = 0; i < gdev->ngpio; i++)
+		gdev->descs[i].name = names[i];
+
+	kfree(names);
+}
+
 void acpi_gpiochip_add(struct gpio_chip *chip)
 {
 	struct acpi_gpio_chip *acpi_gpio;
@@ -835,6 +875,9 @@ void acpi_gpiochip_add(struct gpio_chip *chip)
 		return;
 	}
 
+	if (!chip->names)
+		acpi_gpiochip_set_names(acpi_gpio);
+
 	acpi_gpiochip_request_regions(acpi_gpio);
 	acpi_walk_dep_device_list(handle);
 }
-- 
2.9.3