From fd9c55315db9bc89c54bb644a0f8b1f9306010d4 Mon Sep 17 00:00:00 2001 From: Linus Walleij Date: Tue, 19 Apr 2016 15:26:26 +0200 Subject: 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 Cc: Amit Kucheria Cc: David Mandala Cc: Lee Campbell Cc: devicetree@vger.kernel.org Acked-by: Rob Herring Reviewed-by: Michael Welling Signed-off-by: Linus Walleij --- drivers/gpio/gpiolib-of.c | 49 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 49 insertions(+) (limited to 'drivers/gpio') diff --git a/drivers/gpio/gpiolib-of.c b/drivers/gpio/gpiolib-of.c index d81dbd8..d22dcc3 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); -- cgit v1.1