summaryrefslogtreecommitdiffstats
path: root/drivers/gpio/gpiolib-of.c
diff options
context:
space:
mode:
authorLinus Walleij <linus.walleij@linaro.org>2016-04-19 15:26:26 +0200
committerLinus Walleij <linus.walleij@linaro.org>2016-05-10 13:43:48 +0200
commitfd9c55315db9bc89c54bb644a0f8b1f9306010d4 (patch)
tree4ea19200e1902c9ba5991a10cd6b6b62acb1c242 /drivers/gpio/gpiolib-of.c
parentgpio: make gpiod_to_irq() return negative for NO_IRQ (diff)
downloadlinux-fd9c55315db9bc89c54bb644a0f8b1f9306010d4.tar.xz
linux-fd9c55315db9bc89c54bb644a0f8b1f9306010d4.zip
gpio: of: make it possible to name GPIO lines
Make it possible to name the producer side of a GPIO line using a "gpio-line-names" property array, modeled on the "clock-output-names" property from the clock bindings. This naming is especially useful for: - Debugging: lines are named after function, not just opaque offset numbers. - Exploration: systems where some or all GPIO lines are available to end users, such as prototyping, one-off's "makerspace usecases" users are helped by the names of the GPIO lines when tinkering. This usecase has been surfacing recently. The gpio-line-names attribute is completely optional. Example output from lsgpio on a patched Snowball tree: GPIO chip: gpiochip6, "8000e180.gpio", 32 GPIO lines line 0: unnamed unused line 1: "AP_GPIO161" "extkb3" [kernel] line 2: "AP_GPIO162" "extkb4" [kernel] line 3: "ACCELEROMETER_INT1_RDY" unused [kernel] line 4: "ACCELEROMETER_INT2" unused line 5: "MAG_DRDY" unused [kernel] line 6: "GYRO_DRDY" unused [kernel] line 7: "RSTn_MLC" unused line 8: "RSTn_SLC" unused line 9: "GYRO_INT" unused line 10: "UART_WAKE" unused line 11: "GBF_RESET" unused line 12: unnamed unused Cc: Grant Likely <grant.likely@linaro.org> Cc: Amit Kucheria <amit.kucheria@linaro.org> Cc: David Mandala <david.mandala@linaro.org> Cc: Lee Campbell <leecam@google.com> Cc: devicetree@vger.kernel.org Acked-by: Rob Herring <robh@kernel.org> Reviewed-by: Michael Welling <mwelling@ieee.org> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Diffstat (limited to 'drivers/gpio/gpiolib-of.c')
-rw-r--r--drivers/gpio/gpiolib-of.c49
1 files changed, 49 insertions, 0 deletions
diff --git a/drivers/gpio/gpiolib-of.c b/drivers/gpio/gpiolib-of.c
index d81dbd8e90d9..d22dcc38179d 100644
--- a/drivers/gpio/gpiolib-of.c
+++ b/drivers/gpio/gpiolib-of.c
@@ -196,6 +196,51 @@ static struct gpio_desc *of_parse_own_gpio(struct device_node *np,
}
/**
+ * of_gpiochip_set_names() - set up the names of the lines
+ * @chip: GPIO chip whose lines should be named, if possible
+ */
+static void of_gpiochip_set_names(struct gpio_chip *gc)
+{
+ struct gpio_device *gdev = gc->gpiodev;
+ struct device_node *np = gc->of_node;
+ int i;
+ int nstrings;
+
+ nstrings = of_property_count_strings(np, "gpio-line-names");
+ if (nstrings <= 0)
+ /* Lines names not present */
+ return;
+
+ /* This is normally not what you want */
+ if (gdev->ngpio != nstrings)
+ dev_info(&gdev->dev, "gpio-line-names specifies %d line "
+ "names but there are %d lines on the chip\n",
+ nstrings, gdev->ngpio);
+
+ /*
+ * Make sure to not index beyond the end of the number of descriptors
+ * of the GPIO device.
+ */
+ for (i = 0; i < gdev->ngpio; i++) {
+ const char *name;
+ int ret;
+
+ ret = of_property_read_string_index(np,
+ "gpio-line-names",
+ i,
+ &name);
+ if (ret) {
+ if (ret != -ENODATA)
+ dev_err(&gdev->dev,
+ "unable to name line %d: %d\n",
+ i, ret);
+ break;
+ }
+ gdev->descs[i].name = name;
+ }
+}
+
+/**
* of_gpiochip_scan_gpios - Scan gpio-controller for gpio definitions
* @chip: gpio chip to act on
*
@@ -445,6 +490,10 @@ int of_gpiochip_add(struct gpio_chip *chip)
if (status)
return status;
+ /* If the chip defines names itself, these take precedence */
+ if (!chip->names)
+ of_gpiochip_set_names(chip);
+
of_node_get(chip->of_node);
return of_gpiochip_scan_gpios(chip);