diff options
Diffstat (limited to 'drivers/input/keyboard/adc-keys.c')
| -rw-r--r-- | drivers/input/keyboard/adc-keys.c | 207 |
1 files changed, 207 insertions, 0 deletions
diff --git a/drivers/input/keyboard/adc-keys.c b/drivers/input/keyboard/adc-keys.c new file mode 100644 index 0000000000..bf72ab8df8 --- /dev/null +++ b/drivers/input/keyboard/adc-keys.c @@ -0,0 +1,207 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Input driver for resistor ladder connected on ADC + * + * Copyright (c) 2016 Alexandre Belloni + */ + +#include <linux/err.h> +#include <linux/iio/consumer.h> +#include <linux/iio/types.h> +#include <linux/input.h> +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/of.h> +#include <linux/platform_device.h> +#include <linux/property.h> +#include <linux/slab.h> + +struct adc_keys_button { + u32 voltage; + u32 keycode; +}; + +struct adc_keys_state { + struct iio_channel *channel; + u32 num_keys; + u32 last_key; + u32 keyup_voltage; + const struct adc_keys_button *map; +}; + +static void adc_keys_poll(struct input_dev *input) +{ + struct adc_keys_state *st = input_get_drvdata(input); + int i, value, ret; + u32 diff, closest = 0xffffffff; + int keycode = 0; + + ret = iio_read_channel_processed(st->channel, &value); + if (unlikely(ret < 0)) { + /* Forcibly release key if any was pressed */ + value = st->keyup_voltage; + } else { + for (i = 0; i < st->num_keys; i++) { + diff = abs(st->map[i].voltage - value); + if (diff < closest) { + closest = diff; + keycode = st->map[i].keycode; + } + } + } + + if (abs(st->keyup_voltage - value) < closest) + keycode = 0; + + if (st->last_key && st->last_key != keycode) + input_report_key(input, st->last_key, 0); + + if (keycode) + input_report_key(input, keycode, 1); + + input_sync(input); + st->last_key = keycode; +} + +static int adc_keys_load_keymap(struct device *dev, struct adc_keys_state *st) +{ + struct adc_keys_button *map; + struct fwnode_handle *child; + int i; + + st->num_keys = device_get_child_node_count(dev); + if (st->num_keys == 0) { + dev_err(dev, "keymap is missing\n"); + return -EINVAL; + } + + map = devm_kmalloc_array(dev, st->num_keys, sizeof(*map), GFP_KERNEL); + if (!map) + return -ENOMEM; + + i = 0; + device_for_each_child_node(dev, child) { + if (fwnode_property_read_u32(child, "press-threshold-microvolt", + &map[i].voltage)) { + dev_err(dev, "Key with invalid or missing voltage\n"); + fwnode_handle_put(child); + return -EINVAL; + } + map[i].voltage /= 1000; + + if (fwnode_property_read_u32(child, "linux,code", + &map[i].keycode)) { + dev_err(dev, "Key with invalid or missing linux,code\n"); + fwnode_handle_put(child); + return -EINVAL; + } + + i++; + } + + st->map = map; + return 0; +} + +static int adc_keys_probe(struct platform_device *pdev) +{ + struct device *dev = &pdev->dev; + struct adc_keys_state *st; + struct input_dev *input; + enum iio_chan_type type; + int i, value; + int error; + + st = devm_kzalloc(dev, sizeof(*st), GFP_KERNEL); + if (!st) + return -ENOMEM; + + st->channel = devm_iio_channel_get(dev, "buttons"); + if (IS_ERR(st->channel)) + return PTR_ERR(st->channel); + + if (!st->channel->indio_dev) + return -ENXIO; + + error = iio_get_channel_type(st->channel, &type); + if (error < 0) + return error; + + if (type != IIO_VOLTAGE) { + dev_err(dev, "Incompatible channel type %d\n", type); + return -EINVAL; + } + + if (device_property_read_u32(dev, "keyup-threshold-microvolt", + &st->keyup_voltage)) { + dev_err(dev, "Invalid or missing keyup voltage\n"); + return -EINVAL; + } + st->keyup_voltage /= 1000; + + error = adc_keys_load_keymap(dev, st); + if (error) + return error; + + input = devm_input_allocate_device(dev); + if (!input) { + dev_err(dev, "failed to allocate input device\n"); + return -ENOMEM; + } + + input_set_drvdata(input, st); + + input->name = pdev->name; + input->phys = "adc-keys/input0"; + + input->id.bustype = BUS_HOST; + input->id.vendor = 0x0001; + input->id.product = 0x0001; + input->id.version = 0x0100; + + __set_bit(EV_KEY, input->evbit); + for (i = 0; i < st->num_keys; i++) + __set_bit(st->map[i].keycode, input->keybit); + + if (device_property_read_bool(dev, "autorepeat")) + __set_bit(EV_REP, input->evbit); + + + error = input_setup_polling(input, adc_keys_poll); + if (error) { + dev_err(dev, "Unable to set up polling: %d\n", error); + return error; + } + + if (!device_property_read_u32(dev, "poll-interval", &value)) + input_set_poll_interval(input, value); + + error = input_register_device(input); + if (error) { + dev_err(dev, "Unable to register input device: %d\n", error); + return error; + } + + return 0; +} + +#ifdef CONFIG_OF +static const struct of_device_id adc_keys_of_match[] = { + { .compatible = "adc-keys", }, + { } +}; +MODULE_DEVICE_TABLE(of, adc_keys_of_match); +#endif + +static struct platform_driver adc_keys_driver = { + .driver = { + .name = "adc_keys", + .of_match_table = of_match_ptr(adc_keys_of_match), + }, + .probe = adc_keys_probe, +}; +module_platform_driver(adc_keys_driver); + +MODULE_AUTHOR("Alexandre Belloni <alexandre.belloni@free-electrons.com>"); +MODULE_DESCRIPTION("Input driver for resistor ladder connected on ADC"); +MODULE_LICENSE("GPL v2"); |