diff options
-rw-r--r-- | Documentation/input/rotary-encoder.rst | 85 |
1 files changed, 44 insertions, 41 deletions
diff --git a/Documentation/input/rotary-encoder.rst b/Documentation/input/rotary-encoder.rst index 4695bea67f9b..b07b20a295ac 100644 --- a/Documentation/input/rotary-encoder.rst +++ b/Documentation/input/rotary-encoder.rst | |||
@@ -81,48 +81,51 @@ Board integration | |||
81 | 81 | ||
82 | To use this driver in your system, register a platform_device with the | 82 | To use this driver in your system, register a platform_device with the |
83 | name 'rotary-encoder' and associate the IRQs and some specific platform | 83 | name 'rotary-encoder' and associate the IRQs and some specific platform |
84 | data with it. | 84 | data with it. Because the driver uses generic device properties, this can |
85 | be done either via device tree, ACPI, or using static board files, like in | ||
86 | example below: | ||
85 | 87 | ||
86 | struct rotary_encoder_platform_data is declared in | 88 | :: |
87 | include/linux/rotary-encoder.h and needs to be filled with the number of | ||
88 | steps the encoder has and can carry information about externally inverted | ||
89 | signals (because of an inverting buffer or other reasons). The encoder | ||
90 | can be set up to deliver input information as either an absolute or relative | ||
91 | axes. For relative axes the input event returns +/-1 for each step. For | ||
92 | absolute axes the position of the encoder can either roll over between zero | ||
93 | and the number of steps or will clamp at the maximum and zero depending on | ||
94 | the configuration. | ||
95 | 89 | ||
96 | Because GPIO to IRQ mapping is platform specific, this information must | 90 | /* board support file example */ |
97 | be given in separately to the driver. See the example below. | ||
98 | 91 | ||
99 | :: | 92 | #include <linux/input.h> |
93 | #include <linux/gpio/machine.h> | ||
94 | #include <linux/property.h> | ||
95 | |||
96 | #define GPIO_ROTARY_A 1 | ||
97 | #define GPIO_ROTARY_B 2 | ||
98 | |||
99 | static struct gpiod_lookup_table rotary_encoder_gpios = { | ||
100 | .dev_id = "rotary-encoder.0", | ||
101 | .table = { | ||
102 | GPIO_LOOKUP_IDX("gpio-0", | ||
103 | GPIO_ROTARY_A, NULL, 0, GPIO_ACTIVE_LOW), | ||
104 | GPIO_LOOKUP_IDX("gpio-0", | ||
105 | GPIO_ROTARY_B, NULL, 1, GPIO_ACTIVE_HIGH), | ||
106 | { }, | ||
107 | }, | ||
108 | }; | ||
109 | |||
110 | static const struct property_entry rotary_encoder_properties[] __initconst = { | ||
111 | PROPERTY_ENTRY_INTEGER("rotary-encoder,steps-per-period", u32, 24), | ||
112 | PROPERTY_ENTRY_INTEGER("linux,axis", u32, ABS_X), | ||
113 | PROPERTY_ENTRY_INTEGER("rotary-encoder,relative_axis", u32, 0), | ||
114 | { }, | ||
115 | }; | ||
116 | |||
117 | static struct platform_device rotary_encoder_device = { | ||
118 | .name = "rotary-encoder", | ||
119 | .id = 0, | ||
120 | }; | ||
121 | |||
122 | ... | ||
123 | |||
124 | gpiod_add_lookup_table(&rotary_encoder_gpios); | ||
125 | device_add_properties(&rotary_encoder_device, rotary_encoder_properties); | ||
126 | platform_device_register(&rotary_encoder_device); | ||
127 | |||
128 | ... | ||
100 | 129 | ||
101 | /* board support file example */ | 130 | Please consult device tree binding documentation to see all properties |
102 | 131 | supported by the driver. | |
103 | #include <linux/input.h> | ||
104 | #include <linux/rotary_encoder.h> | ||
105 | |||
106 | #define GPIO_ROTARY_A 1 | ||
107 | #define GPIO_ROTARY_B 2 | ||
108 | |||
109 | static struct rotary_encoder_platform_data my_rotary_encoder_info = { | ||
110 | .steps = 24, | ||
111 | .axis = ABS_X, | ||
112 | .relative_axis = false, | ||
113 | .rollover = false, | ||
114 | .gpio_a = GPIO_ROTARY_A, | ||
115 | .gpio_b = GPIO_ROTARY_B, | ||
116 | .inverted_a = 0, | ||
117 | .inverted_b = 0, | ||
118 | .half_period = false, | ||
119 | .wakeup_source = false, | ||
120 | }; | ||
121 | |||
122 | static struct platform_device rotary_encoder_device = { | ||
123 | .name = "rotary-encoder", | ||
124 | .id = 0, | ||
125 | .dev = { | ||
126 | .platform_data = &my_rotary_encoder_info, | ||
127 | } | ||
128 | }; | ||