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author | Linus Walleij <linus.walleij@linaro.org> | 2016-04-19 15:26:26 +0200 |
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committer | Linus Walleij <linus.walleij@linaro.org> | 2016-05-10 13:43:48 +0200 |
commit | fd9c55315db9bc89c54bb644a0f8b1f9306010d4 (patch) | |
tree | 4ea19200e1902c9ba5991a10cd6b6b62acb1c242 /drivers/gpio/gpiolib-of.c | |
parent | gpio: make gpiod_to_irq() return negative for NO_IRQ (diff) | |
download | linux-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.c | 49 |
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); |