Difference between revisions of "GPIO keys"
Line 20: | Line 20: | ||
</pre> | </pre> | ||
+ | === Without device tree === | ||
Then, in your ''apfXX-dev.c'', you would need to define your GPIO button <b>before</b> the variable ''platform_devices[]'' and also include gpio_keys.h and input.h. his code is already implemented for the APF27, APF28 and APF51 so the source code hereafter (for the APF27) is only present as a reference sample to understand how to activate a GPIO KEY driver. | Then, in your ''apfXX-dev.c'', you would need to define your GPIO button <b>before</b> the variable ''platform_devices[]'' and also include gpio_keys.h and input.h. his code is already implemented for the APF27, APF28 and APF51 so the source code hereafter (for the APF27) is only present as a reference sample to understand how to activate a GPIO KEY driver. | ||
Line 66: | Line 67: | ||
}; | }; | ||
</source> | </source> | ||
+ | |||
+ | === With device tree === | ||
+ | This description is based to the APF28dev board. | ||
+ | |||
+ | To define gpio-keys, you need to add a node and a sub-node after all peripheral nodes : | ||
+ | <source lang="c"> | ||
+ | gpio-keys { | ||
+ | compatible = "gpio-keys"; | ||
+ | |||
+ | left-key { | ||
+ | label = "Left key"; | ||
+ | gpios = <&gpio1 18 0>; | ||
+ | linux,code = <69>; /* KEY_LEFT */ | ||
+ | }; | ||
+ | } | ||
+ | </source> | ||
+ | |||
+ | It is possible to add as many node you want (within the limits of available pins). | ||
+ | |||
+ | A key node contains : | ||
+ | * a name (left-key) | ||
+ | * a label | ||
+ | * a gpio <&gpioX Y 0> with X is the bank number and Y the pin number | ||
+ | * a linux code, available in buildroot/output/build/linux-xxx/include/uapi/linux/input.h | ||
+ | |||
+ | For each key, you need to add the corresponding GPIO in hog sub-node of pinctrl node | ||
+ | <source lang="c"> | ||
+ | hog_pins_apf28dev: hog@0 { | ||
+ | ... | ||
+ | fsl,pinmux-ids = < | ||
+ | ... | ||
+ | 0x1123 /* MX28_PAD_LCD_D18__GPIO_1_18 */ | ||
+ | ... | ||
+ | >; | ||
+ | ... | ||
+ | }; | ||
+ | </source> | ||
+ | The pinmux is available in buildroot/output/build/linux-xxx/Documentation/devicetree/bindings/pinctrl/fsl,mxs-pinctrl.txt | ||
==Usage== | ==Usage== |
Revision as of 19:17, 29 January 2013
Contents
Introduction
How to use gpio-keys driver to read states of the user switch of your Armadeus board. Your APF51|APF27|APF28 development board feature a user switch connected to a GPIO pin. The driver gpio-keys translates GPIO events in key/button events. Here are the GPIO used for the user button/switch for each APF board:
- APF27: GPIO_PORTF | 13
- APF28: PINID_GPMI_CE1N (Bank 0 - bit 17)
- APF51: GPIO1_3
Configuration
First, you need to enable the gpio_keys in your kernel.
Device Drivers ---> Input device support ---> <*> Event interface [*] Keyboards ---> <*> GPIO Buttons
Without device tree
Then, in your apfXX-dev.c, you would need to define your GPIO button before the variable platform_devices[] and also include gpio_keys.h and input.h. his code is already implemented for the APF27, APF28 and APF51 so the source code hereafter (for the APF27) is only present as a reference sample to understand how to activate a GPIO KEY driver.
#include <linux/gpio_keys.h>
#include <linux/input.h>
/* GPIO KEYS */
#if defined(CONFIG_KEYBOARD_GPIO) || defined(CONFIG_KEYBOARD_GPIO_MODULE)
static struct gpio_keys_button apf27dev_gpio_keys[] = {
{
.code = BTN_EXTRA, /* See include/linux/input.h */
.gpio = (GPIO_PORTF | 13), /* GPIO number */
.active_low = 1,
.desc = "s1", /* Button description*/
.wakeup = 0,
},
};
static struct gpio_keys_platform_data apf27dev_gpio_keys_data = {
.buttons = apf27dev_gpio_keys,
.nbuttons = ARRAY_SIZE(apf27dev_gpio_keys),
};
static struct platform_device apf27dev_gpio_keys_device = {
.name = "gpio-keys",
.id = -1,
.dev = {
.platform_data = &apf27dev_gpio_keys_data,
},
};
#endif /* CONFIG_KEYBOARD_GPIO */
Add the button to get it recognized by the card.
static struct platform_device *platform_devices[] __initdata = {
#if defined(CONFIG_KEYBOARD_GPIO) || defined(CONFIG_KEYBOARD_GPIO_MODULE)
&apf27dev_gpio_keys_device,
#endif
ALSA_SOUND
};
With device tree
This description is based to the APF28dev board.
To define gpio-keys, you need to add a node and a sub-node after all peripheral nodes :
gpio-keys {
compatible = "gpio-keys";
left-key {
label = "Left key";
gpios = <&gpio1 18 0>;
linux,code = <69>; /* KEY_LEFT */
};
}
It is possible to add as many node you want (within the limits of available pins).
A key node contains :
* a name (left-key) * a label * a gpio <&gpioX Y 0> with X is the bank number and Y the pin number * a linux code, available in buildroot/output/build/linux-xxx/include/uapi/linux/input.h
For each key, you need to add the corresponding GPIO in hog sub-node of pinctrl node
hog_pins_apf28dev: hog@0 {
...
fsl,pinmux-ids = <
...
0x1123 /* MX28_PAD_LCD_D18__GPIO_1_18 */
...
>;
...
};
The pinmux is available in buildroot/output/build/linux-xxx/Documentation/devicetree/bindings/pinctrl/fsl,mxs-pinctrl.txt
Usage
# cat /dev/input/event0
Then you should see weirds characters when pressing the user button of the apf51_dev board:
T ����T �T � ��T %�
- if the test wiped out your console, you can get it back with:
# reset
You also can use the tool evtest.
Hardware handling ---> [*] input-tools [*] evtest
# evtest /dev/input/event0 ... Event: time 1335981358.550329, type 22 (EV_PWR), code 0 (), value 1 Event: time 1335981358.550330, -------------- SYN_REPORT ------------ Event: time 1335981358.550329, type 22 (EV_PWR), code 0 (), value 0 Event: time 1335981358.550330, -------------- SYN_REPORT ------------