Thomas Gleixner | 9c92ab6 | 2019-05-29 07:17:56 -0700 | [diff] [blame] | 1 | // SPDX-License-Identifier: GPL-2.0-only |
Daniel Hung-yu Wu | b06d43f | 2016-05-18 14:55:12 -0700 | [diff] [blame] | 2 | /* |
| 3 | * Atmel Atmegaxx Capacitive Touch Button Driver |
| 4 | * |
| 5 | * Copyright (C) 2016 Google, inc. |
Daniel Hung-yu Wu | b06d43f | 2016-05-18 14:55:12 -0700 | [diff] [blame] | 6 | */ |
| 7 | |
| 8 | /* |
| 9 | * It's irrelevant that the HW used to develop captouch driver is based |
| 10 | * on Atmega88PA part and uses QtouchADC parts for sensing touch. |
| 11 | * Calling this driver "captouch" is an arbitrary way to distinguish |
| 12 | * the protocol this driver supported by other atmel/qtouch drivers. |
| 13 | * |
| 14 | * Captouch driver supports a newer/different version of the I2C |
| 15 | * registers/commands than the qt1070.c driver. |
| 16 | * Don't let the similarity of the general driver structure fool you. |
| 17 | * |
| 18 | * For raw i2c access from userspace, use i2cset/i2cget |
| 19 | * to poke at /dev/i2c-N devices. |
| 20 | */ |
| 21 | |
| 22 | #include <linux/device.h> |
| 23 | #include <linux/kernel.h> |
| 24 | #include <linux/module.h> |
| 25 | #include <linux/init.h> |
| 26 | #include <linux/i2c.h> |
| 27 | #include <linux/input.h> |
| 28 | #include <linux/interrupt.h> |
| 29 | #include <linux/slab.h> |
| 30 | |
| 31 | /* Maximum number of buttons supported */ |
| 32 | #define MAX_NUM_OF_BUTTONS 8 |
| 33 | |
| 34 | /* Registers */ |
| 35 | #define REG_KEY1_THRESHOLD 0x02 |
| 36 | #define REG_KEY2_THRESHOLD 0x03 |
| 37 | #define REG_KEY3_THRESHOLD 0x04 |
| 38 | #define REG_KEY4_THRESHOLD 0x05 |
| 39 | |
| 40 | #define REG_KEY1_REF_H 0x20 |
| 41 | #define REG_KEY1_REF_L 0x21 |
| 42 | #define REG_KEY2_REF_H 0x22 |
| 43 | #define REG_KEY2_REF_L 0x23 |
| 44 | #define REG_KEY3_REF_H 0x24 |
| 45 | #define REG_KEY3_REF_L 0x25 |
| 46 | #define REG_KEY4_REF_H 0x26 |
| 47 | #define REG_KEY4_REF_L 0x27 |
| 48 | |
| 49 | #define REG_KEY1_DLT_H 0x30 |
| 50 | #define REG_KEY1_DLT_L 0x31 |
| 51 | #define REG_KEY2_DLT_H 0x32 |
| 52 | #define REG_KEY2_DLT_L 0x33 |
| 53 | #define REG_KEY3_DLT_H 0x34 |
| 54 | #define REG_KEY3_DLT_L 0x35 |
| 55 | #define REG_KEY4_DLT_H 0x36 |
| 56 | #define REG_KEY4_DLT_L 0x37 |
| 57 | |
| 58 | #define REG_KEY_STATE 0x3C |
| 59 | |
| 60 | /* |
| 61 | * @i2c_client: I2C slave device client pointer |
| 62 | * @input: Input device pointer |
| 63 | * @num_btn: Number of buttons |
| 64 | * @keycodes: map of button# to KeyCode |
| 65 | * @prev_btn: Previous key state to detect button "press" or "release" |
| 66 | * @xfer_buf: I2C transfer buffer |
| 67 | */ |
| 68 | struct atmel_captouch_device { |
| 69 | struct i2c_client *client; |
| 70 | struct input_dev *input; |
| 71 | u32 num_btn; |
| 72 | u32 keycodes[MAX_NUM_OF_BUTTONS]; |
| 73 | u8 prev_btn; |
| 74 | u8 xfer_buf[8] ____cacheline_aligned; |
| 75 | }; |
| 76 | |
| 77 | /* |
| 78 | * Read from I2C slave device |
| 79 | * The protocol is that the client has to provide both the register address |
| 80 | * and the length, and while reading back the device would prepend the data |
| 81 | * with address and length for verification. |
| 82 | */ |
| 83 | static int atmel_read(struct atmel_captouch_device *capdev, |
| 84 | u8 reg, u8 *data, size_t len) |
| 85 | { |
| 86 | struct i2c_client *client = capdev->client; |
| 87 | struct device *dev = &client->dev; |
| 88 | struct i2c_msg msg[2]; |
| 89 | int err; |
| 90 | |
| 91 | if (len > sizeof(capdev->xfer_buf) - 2) |
| 92 | return -EINVAL; |
| 93 | |
| 94 | capdev->xfer_buf[0] = reg; |
| 95 | capdev->xfer_buf[1] = len; |
| 96 | |
| 97 | msg[0].addr = client->addr; |
| 98 | msg[0].flags = 0; |
| 99 | msg[0].buf = capdev->xfer_buf; |
| 100 | msg[0].len = 2; |
| 101 | |
| 102 | msg[1].addr = client->addr; |
| 103 | msg[1].flags = I2C_M_RD; |
| 104 | msg[1].buf = capdev->xfer_buf; |
| 105 | msg[1].len = len + 2; |
| 106 | |
| 107 | err = i2c_transfer(client->adapter, msg, ARRAY_SIZE(msg)); |
| 108 | if (err != ARRAY_SIZE(msg)) |
| 109 | return err < 0 ? err : -EIO; |
| 110 | |
| 111 | if (capdev->xfer_buf[0] != reg) { |
| 112 | dev_err(dev, |
| 113 | "I2C read error: register address does not match (%#02x vs %02x)\n", |
| 114 | capdev->xfer_buf[0], reg); |
| 115 | return -ECOMM; |
| 116 | } |
| 117 | |
| 118 | memcpy(data, &capdev->xfer_buf[2], len); |
| 119 | |
| 120 | return 0; |
| 121 | } |
| 122 | |
| 123 | /* |
| 124 | * Handle interrupt and report the key changes to the input system. |
| 125 | * Multi-touch can be supported; however, it really depends on whether |
| 126 | * the device can multi-touch. |
| 127 | */ |
| 128 | static irqreturn_t atmel_captouch_isr(int irq, void *data) |
| 129 | { |
| 130 | struct atmel_captouch_device *capdev = data; |
| 131 | struct device *dev = &capdev->client->dev; |
| 132 | int error; |
| 133 | int i; |
| 134 | u8 new_btn; |
| 135 | u8 changed_btn; |
| 136 | |
| 137 | error = atmel_read(capdev, REG_KEY_STATE, &new_btn, 1); |
| 138 | if (error) { |
| 139 | dev_err(dev, "failed to read button state: %d\n", error); |
| 140 | goto out; |
| 141 | } |
| 142 | |
| 143 | dev_dbg(dev, "%s: button state %#02x\n", __func__, new_btn); |
| 144 | |
| 145 | changed_btn = new_btn ^ capdev->prev_btn; |
| 146 | capdev->prev_btn = new_btn; |
| 147 | |
| 148 | for (i = 0; i < capdev->num_btn; i++) { |
| 149 | if (changed_btn & BIT(i)) |
| 150 | input_report_key(capdev->input, |
| 151 | capdev->keycodes[i], |
| 152 | new_btn & BIT(i)); |
| 153 | } |
| 154 | |
| 155 | input_sync(capdev->input); |
| 156 | |
| 157 | out: |
| 158 | return IRQ_HANDLED; |
| 159 | } |
| 160 | |
| 161 | /* |
| 162 | * Probe function to setup the device, input system and interrupt |
| 163 | */ |
| 164 | static int atmel_captouch_probe(struct i2c_client *client, |
| 165 | const struct i2c_device_id *id) |
| 166 | { |
| 167 | struct atmel_captouch_device *capdev; |
| 168 | struct device *dev = &client->dev; |
| 169 | struct device_node *node; |
| 170 | int i; |
| 171 | int err; |
| 172 | |
| 173 | if (!i2c_check_functionality(client->adapter, |
| 174 | I2C_FUNC_SMBUS_BYTE_DATA | |
| 175 | I2C_FUNC_SMBUS_WORD_DATA | |
| 176 | I2C_FUNC_SMBUS_I2C_BLOCK)) { |
| 177 | dev_err(dev, "needed i2c functionality is not supported\n"); |
| 178 | return -EINVAL; |
| 179 | } |
| 180 | |
| 181 | capdev = devm_kzalloc(dev, sizeof(*capdev), GFP_KERNEL); |
| 182 | if (!capdev) |
| 183 | return -ENOMEM; |
| 184 | |
| 185 | capdev->client = client; |
Daniel Hung-yu Wu | b06d43f | 2016-05-18 14:55:12 -0700 | [diff] [blame] | 186 | |
| 187 | err = atmel_read(capdev, REG_KEY_STATE, |
| 188 | &capdev->prev_btn, sizeof(capdev->prev_btn)); |
| 189 | if (err) { |
| 190 | dev_err(dev, "failed to read initial button state: %d\n", err); |
| 191 | return err; |
| 192 | } |
| 193 | |
| 194 | capdev->input = devm_input_allocate_device(dev); |
| 195 | if (!capdev->input) { |
| 196 | dev_err(dev, "failed to allocate input device\n"); |
| 197 | return -ENOMEM; |
| 198 | } |
| 199 | |
| 200 | capdev->input->id.bustype = BUS_I2C; |
| 201 | capdev->input->id.product = 0x880A; |
| 202 | capdev->input->id.version = 0; |
| 203 | capdev->input->name = "ATMegaXX Capacitive Button Controller"; |
| 204 | __set_bit(EV_KEY, capdev->input->evbit); |
| 205 | |
| 206 | node = dev->of_node; |
| 207 | if (!node) { |
| 208 | dev_err(dev, "failed to find matching node in device tree\n"); |
| 209 | return -EINVAL; |
| 210 | } |
| 211 | |
| 212 | if (of_property_read_bool(node, "autorepeat")) |
| 213 | __set_bit(EV_REP, capdev->input->evbit); |
| 214 | |
| 215 | capdev->num_btn = of_property_count_u32_elems(node, "linux,keymap"); |
| 216 | if (capdev->num_btn > MAX_NUM_OF_BUTTONS) |
| 217 | capdev->num_btn = MAX_NUM_OF_BUTTONS; |
| 218 | |
| 219 | err = of_property_read_u32_array(node, "linux,keycodes", |
| 220 | capdev->keycodes, |
| 221 | capdev->num_btn); |
| 222 | if (err) { |
| 223 | dev_err(dev, |
| 224 | "failed to read linux,keycode property: %d\n", err); |
| 225 | return err; |
| 226 | } |
| 227 | |
| 228 | for (i = 0; i < capdev->num_btn; i++) |
| 229 | __set_bit(capdev->keycodes[i], capdev->input->keybit); |
| 230 | |
| 231 | capdev->input->keycode = capdev->keycodes; |
| 232 | capdev->input->keycodesize = sizeof(capdev->keycodes[0]); |
| 233 | capdev->input->keycodemax = capdev->num_btn; |
| 234 | |
| 235 | err = input_register_device(capdev->input); |
| 236 | if (err) |
| 237 | return err; |
| 238 | |
| 239 | err = devm_request_threaded_irq(dev, client->irq, |
| 240 | NULL, atmel_captouch_isr, |
| 241 | IRQF_ONESHOT, |
| 242 | "atmel_captouch", capdev); |
| 243 | if (err) { |
| 244 | dev_err(dev, "failed to request irq %d: %d\n", |
| 245 | client->irq, err); |
| 246 | return err; |
| 247 | } |
| 248 | |
| 249 | return 0; |
| 250 | } |
| 251 | |
| 252 | #ifdef CONFIG_OF |
| 253 | static const struct of_device_id atmel_captouch_of_id[] = { |
| 254 | { |
| 255 | .compatible = "atmel,captouch", |
| 256 | }, |
| 257 | { /* sentinel */ } |
| 258 | }; |
| 259 | MODULE_DEVICE_TABLE(of, atmel_captouch_of_id); |
| 260 | #endif |
| 261 | |
| 262 | static const struct i2c_device_id atmel_captouch_id[] = { |
| 263 | { "atmel_captouch", 0 }, |
| 264 | { } |
| 265 | }; |
| 266 | MODULE_DEVICE_TABLE(i2c, atmel_captouch_id); |
| 267 | |
| 268 | static struct i2c_driver atmel_captouch_driver = { |
| 269 | .probe = atmel_captouch_probe, |
| 270 | .id_table = atmel_captouch_id, |
| 271 | .driver = { |
| 272 | .name = "atmel_captouch", |
| 273 | .of_match_table = of_match_ptr(atmel_captouch_of_id), |
| 274 | }, |
| 275 | }; |
| 276 | module_i2c_driver(atmel_captouch_driver); |
| 277 | |
| 278 | /* Module information */ |
| 279 | MODULE_AUTHOR("Hung-yu Wu <hywu@google.com>"); |
| 280 | MODULE_DESCRIPTION("Atmel ATmegaXX Capacitance Touch Sensor I2C Driver"); |
| 281 | MODULE_LICENSE("GPL v2"); |