| // SPDX-License-Identifier: GPL-2.0-or-later |
| /* |
| * Driver for a keypad w/16 buttons connected to a PCF8574 I2C I/O expander |
| * |
| * Copyright 2005-2008 Analog Devices Inc. |
| */ |
| |
| #include <linux/module.h> |
| #include <linux/input.h> |
| #include <linux/interrupt.h> |
| #include <linux/i2c.h> |
| #include <linux/slab.h> |
| #include <linux/workqueue.h> |
| |
| #define DRV_NAME "pcf8574_keypad" |
| |
| static const unsigned char pcf8574_kp_btncode[] = { |
| [0] = KEY_RESERVED, |
| [1] = KEY_ENTER, |
| [2] = KEY_BACKSLASH, |
| [3] = KEY_0, |
| [4] = KEY_RIGHTBRACE, |
| [5] = KEY_C, |
| [6] = KEY_9, |
| [7] = KEY_8, |
| [8] = KEY_7, |
| [9] = KEY_B, |
| [10] = KEY_6, |
| [11] = KEY_5, |
| [12] = KEY_4, |
| [13] = KEY_A, |
| [14] = KEY_3, |
| [15] = KEY_2, |
| [16] = KEY_1 |
| }; |
| |
| struct kp_data { |
| unsigned short btncode[ARRAY_SIZE(pcf8574_kp_btncode)]; |
| struct input_dev *idev; |
| struct i2c_client *client; |
| char name[64]; |
| char phys[32]; |
| unsigned char laststate; |
| }; |
| |
| static short read_state(struct kp_data *lp) |
| { |
| unsigned char x, y, a, b; |
| |
| i2c_smbus_write_byte(lp->client, 240); |
| x = 0xF & (~(i2c_smbus_read_byte(lp->client) >> 4)); |
| |
| i2c_smbus_write_byte(lp->client, 15); |
| y = 0xF & (~i2c_smbus_read_byte(lp->client)); |
| |
| for (a = 0; x > 0; a++) |
| x = x >> 1; |
| for (b = 0; y > 0; b++) |
| y = y >> 1; |
| |
| return ((a - 1) * 4) + b; |
| } |
| |
| static irqreturn_t pcf8574_kp_irq_handler(int irq, void *dev_id) |
| { |
| struct kp_data *lp = dev_id; |
| unsigned char nextstate = read_state(lp); |
| |
| if (lp->laststate != nextstate) { |
| int key_down = nextstate < ARRAY_SIZE(lp->btncode); |
| unsigned short keycode = key_down ? |
| lp->btncode[nextstate] : lp->btncode[lp->laststate]; |
| |
| input_report_key(lp->idev, keycode, key_down); |
| input_sync(lp->idev); |
| |
| lp->laststate = nextstate; |
| } |
| |
| return IRQ_HANDLED; |
| } |
| |
| static int pcf8574_kp_probe(struct i2c_client *client) |
| { |
| int i, ret; |
| struct input_dev *idev; |
| struct kp_data *lp; |
| |
| if (i2c_smbus_write_byte(client, 240) < 0) { |
| dev_err(&client->dev, "probe: write fail\n"); |
| return -ENODEV; |
| } |
| |
| lp = kzalloc(sizeof(*lp), GFP_KERNEL); |
| if (!lp) |
| return -ENOMEM; |
| |
| idev = input_allocate_device(); |
| if (!idev) { |
| dev_err(&client->dev, "Can't allocate input device\n"); |
| ret = -ENOMEM; |
| goto fail_allocate; |
| } |
| |
| lp->idev = idev; |
| lp->client = client; |
| |
| idev->evbit[0] = BIT_MASK(EV_KEY); |
| idev->keycode = lp->btncode; |
| idev->keycodesize = sizeof(lp->btncode[0]); |
| idev->keycodemax = ARRAY_SIZE(lp->btncode); |
| |
| for (i = 0; i < ARRAY_SIZE(pcf8574_kp_btncode); i++) { |
| if (lp->btncode[i] <= KEY_MAX) { |
| lp->btncode[i] = pcf8574_kp_btncode[i]; |
| __set_bit(lp->btncode[i], idev->keybit); |
| } |
| } |
| __clear_bit(KEY_RESERVED, idev->keybit); |
| |
| sprintf(lp->name, DRV_NAME); |
| sprintf(lp->phys, "kp_data/input0"); |
| |
| idev->name = lp->name; |
| idev->phys = lp->phys; |
| idev->id.bustype = BUS_I2C; |
| idev->id.vendor = 0x0001; |
| idev->id.product = 0x0001; |
| idev->id.version = 0x0100; |
| |
| lp->laststate = read_state(lp); |
| |
| ret = request_threaded_irq(client->irq, NULL, pcf8574_kp_irq_handler, |
| IRQF_TRIGGER_LOW | IRQF_ONESHOT, |
| DRV_NAME, lp); |
| if (ret) { |
| dev_err(&client->dev, "IRQ %d is not free\n", client->irq); |
| goto fail_free_device; |
| } |
| |
| ret = input_register_device(idev); |
| if (ret) { |
| dev_err(&client->dev, "input_register_device() failed\n"); |
| goto fail_free_irq; |
| } |
| |
| i2c_set_clientdata(client, lp); |
| return 0; |
| |
| fail_free_irq: |
| free_irq(client->irq, lp); |
| fail_free_device: |
| input_free_device(idev); |
| fail_allocate: |
| kfree(lp); |
| |
| return ret; |
| } |
| |
| static void pcf8574_kp_remove(struct i2c_client *client) |
| { |
| struct kp_data *lp = i2c_get_clientdata(client); |
| |
| free_irq(client->irq, lp); |
| |
| input_unregister_device(lp->idev); |
| kfree(lp); |
| } |
| |
| static int pcf8574_kp_resume(struct device *dev) |
| { |
| struct i2c_client *client = to_i2c_client(dev); |
| |
| enable_irq(client->irq); |
| |
| return 0; |
| } |
| |
| static int pcf8574_kp_suspend(struct device *dev) |
| { |
| struct i2c_client *client = to_i2c_client(dev); |
| |
| disable_irq(client->irq); |
| |
| return 0; |
| } |
| |
| static DEFINE_SIMPLE_DEV_PM_OPS(pcf8574_kp_pm_ops, |
| pcf8574_kp_suspend, pcf8574_kp_resume); |
| |
| static const struct i2c_device_id pcf8574_kp_id[] = { |
| { DRV_NAME, 0 }, |
| { } |
| }; |
| MODULE_DEVICE_TABLE(i2c, pcf8574_kp_id); |
| |
| static struct i2c_driver pcf8574_kp_driver = { |
| .driver = { |
| .name = DRV_NAME, |
| .pm = pm_sleep_ptr(&pcf8574_kp_pm_ops), |
| }, |
| .probe = pcf8574_kp_probe, |
| .remove = pcf8574_kp_remove, |
| .id_table = pcf8574_kp_id, |
| }; |
| |
| module_i2c_driver(pcf8574_kp_driver); |
| |
| MODULE_AUTHOR("Michael Hennerich"); |
| MODULE_DESCRIPTION("Keypad input driver for 16 keys connected to PCF8574"); |
| MODULE_LICENSE("GPL"); |