1 | /* |
2 | * Atmel Atmegaxx Capacitive Touch Button Driver |
3 | * |
4 | * Copyright (C) 2016 Google, inc. |
5 | * |
6 | * This software is licensed under the terms of the GNU General Public |
7 | * License version 2, as published by the Free Software Foundation, and |
8 | * may be copied, distributed, and modified under those terms. |
9 | * |
10 | * This program is distributed in the hope that it will be useful, |
11 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
12 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
13 | * GNU General Public License for more details. |
14 | */ |
15 | |
16 | /* |
17 | * It's irrelevant that the HW used to develop captouch driver is based |
18 | * on Atmega88PA part and uses QtouchADC parts for sensing touch. |
19 | * Calling this driver "captouch" is an arbitrary way to distinguish |
20 | * the protocol this driver supported by other atmel/qtouch drivers. |
21 | * |
22 | * Captouch driver supports a newer/different version of the I2C |
23 | * registers/commands than the qt1070.c driver. |
24 | * Don't let the similarity of the general driver structure fool you. |
25 | * |
26 | * For raw i2c access from userspace, use i2cset/i2cget |
27 | * to poke at /dev/i2c-N devices. |
28 | */ |
29 | |
30 | #include <linux/device.h> |
31 | #include <linux/kernel.h> |
32 | #include <linux/module.h> |
33 | #include <linux/init.h> |
34 | #include <linux/i2c.h> |
35 | #include <linux/input.h> |
36 | #include <linux/interrupt.h> |
37 | #include <linux/slab.h> |
38 | |
39 | /* Maximum number of buttons supported */ |
40 | #define MAX_NUM_OF_BUTTONS 8 |
41 | |
42 | /* Registers */ |
43 | #define REG_KEY1_THRESHOLD 0x02 |
44 | #define REG_KEY2_THRESHOLD 0x03 |
45 | #define REG_KEY3_THRESHOLD 0x04 |
46 | #define REG_KEY4_THRESHOLD 0x05 |
47 | |
48 | #define REG_KEY1_REF_H 0x20 |
49 | #define REG_KEY1_REF_L 0x21 |
50 | #define REG_KEY2_REF_H 0x22 |
51 | #define REG_KEY2_REF_L 0x23 |
52 | #define REG_KEY3_REF_H 0x24 |
53 | #define REG_KEY3_REF_L 0x25 |
54 | #define REG_KEY4_REF_H 0x26 |
55 | #define REG_KEY4_REF_L 0x27 |
56 | |
57 | #define REG_KEY1_DLT_H 0x30 |
58 | #define REG_KEY1_DLT_L 0x31 |
59 | #define REG_KEY2_DLT_H 0x32 |
60 | #define REG_KEY2_DLT_L 0x33 |
61 | #define REG_KEY3_DLT_H 0x34 |
62 | #define REG_KEY3_DLT_L 0x35 |
63 | #define REG_KEY4_DLT_H 0x36 |
64 | #define REG_KEY4_DLT_L 0x37 |
65 | |
66 | #define REG_KEY_STATE 0x3C |
67 | |
68 | /* |
69 | * @i2c_client: I2C slave device client pointer |
70 | * @input: Input device pointer |
71 | * @num_btn: Number of buttons |
72 | * @keycodes: map of button# to KeyCode |
73 | * @prev_btn: Previous key state to detect button "press" or "release" |
74 | * @xfer_buf: I2C transfer buffer |
75 | */ |
76 | struct atmel_captouch_device { |
77 | struct i2c_client *client; |
78 | struct input_dev *input; |
79 | u32 num_btn; |
80 | u32 keycodes[MAX_NUM_OF_BUTTONS]; |
81 | u8 prev_btn; |
82 | u8 xfer_buf[8] ____cacheline_aligned; |
83 | }; |
84 | |
85 | /* |
86 | * Read from I2C slave device |
87 | * The protocol is that the client has to provide both the register address |
88 | * and the length, and while reading back the device would prepend the data |
89 | * with address and length for verification. |
90 | */ |
91 | static int atmel_read(struct atmel_captouch_device *capdev, |
92 | u8 reg, u8 *data, size_t len) |
93 | { |
94 | struct i2c_client *client = capdev->client; |
95 | struct device *dev = &client->dev; |
96 | struct i2c_msg msg[2]; |
97 | int err; |
98 | |
99 | if (len > sizeof(capdev->xfer_buf) - 2) |
100 | return -EINVAL; |
101 | |
102 | capdev->xfer_buf[0] = reg; |
103 | capdev->xfer_buf[1] = len; |
104 | |
105 | msg[0].addr = client->addr; |
106 | msg[0].flags = 0; |
107 | msg[0].buf = capdev->xfer_buf; |
108 | msg[0].len = 2; |
109 | |
110 | msg[1].addr = client->addr; |
111 | msg[1].flags = I2C_M_RD; |
112 | msg[1].buf = capdev->xfer_buf; |
113 | msg[1].len = len + 2; |
114 | |
115 | err = i2c_transfer(client->adapter, msg, ARRAY_SIZE(msg)); |
116 | if (err != ARRAY_SIZE(msg)) |
117 | return err < 0 ? err : -EIO; |
118 | |
119 | if (capdev->xfer_buf[0] != reg) { |
120 | dev_err(dev, |
121 | "I2C read error: register address does not match (%#02x vs %02x)\n" , |
122 | capdev->xfer_buf[0], reg); |
123 | return -ECOMM; |
124 | } |
125 | |
126 | memcpy(data, &capdev->xfer_buf[2], len); |
127 | |
128 | return 0; |
129 | } |
130 | |
131 | /* |
132 | * Handle interrupt and report the key changes to the input system. |
133 | * Multi-touch can be supported; however, it really depends on whether |
134 | * the device can multi-touch. |
135 | */ |
136 | static irqreturn_t atmel_captouch_isr(int irq, void *data) |
137 | { |
138 | struct atmel_captouch_device *capdev = data; |
139 | struct device *dev = &capdev->client->dev; |
140 | int error; |
141 | int i; |
142 | u8 new_btn; |
143 | u8 changed_btn; |
144 | |
145 | error = atmel_read(capdev, REG_KEY_STATE, &new_btn, 1); |
146 | if (error) { |
147 | dev_err(dev, "failed to read button state: %d\n" , error); |
148 | goto out; |
149 | } |
150 | |
151 | dev_dbg(dev, "%s: button state %#02x\n" , __func__, new_btn); |
152 | |
153 | changed_btn = new_btn ^ capdev->prev_btn; |
154 | capdev->prev_btn = new_btn; |
155 | |
156 | for (i = 0; i < capdev->num_btn; i++) { |
157 | if (changed_btn & BIT(i)) |
158 | input_report_key(capdev->input, |
159 | capdev->keycodes[i], |
160 | new_btn & BIT(i)); |
161 | } |
162 | |
163 | input_sync(capdev->input); |
164 | |
165 | out: |
166 | return IRQ_HANDLED; |
167 | } |
168 | |
169 | /* |
170 | * Probe function to setup the device, input system and interrupt |
171 | */ |
172 | static int atmel_captouch_probe(struct i2c_client *client, |
173 | const struct i2c_device_id *id) |
174 | { |
175 | struct atmel_captouch_device *capdev; |
176 | struct device *dev = &client->dev; |
177 | struct device_node *node; |
178 | int i; |
179 | int err; |
180 | |
181 | if (!i2c_check_functionality(client->adapter, |
182 | I2C_FUNC_SMBUS_BYTE_DATA | |
183 | I2C_FUNC_SMBUS_WORD_DATA | |
184 | I2C_FUNC_SMBUS_I2C_BLOCK)) { |
185 | dev_err(dev, "needed i2c functionality is not supported\n" ); |
186 | return -EINVAL; |
187 | } |
188 | |
189 | capdev = devm_kzalloc(dev, sizeof(*capdev), GFP_KERNEL); |
190 | if (!capdev) |
191 | return -ENOMEM; |
192 | |
193 | capdev->client = client; |
194 | |
195 | err = atmel_read(capdev, REG_KEY_STATE, |
196 | &capdev->prev_btn, sizeof(capdev->prev_btn)); |
197 | if (err) { |
198 | dev_err(dev, "failed to read initial button state: %d\n" , err); |
199 | return err; |
200 | } |
201 | |
202 | capdev->input = devm_input_allocate_device(dev); |
203 | if (!capdev->input) { |
204 | dev_err(dev, "failed to allocate input device\n" ); |
205 | return -ENOMEM; |
206 | } |
207 | |
208 | capdev->input->id.bustype = BUS_I2C; |
209 | capdev->input->id.product = 0x880A; |
210 | capdev->input->id.version = 0; |
211 | capdev->input->name = "ATMegaXX Capacitive Button Controller" ; |
212 | __set_bit(EV_KEY, capdev->input->evbit); |
213 | |
214 | node = dev->of_node; |
215 | if (!node) { |
216 | dev_err(dev, "failed to find matching node in device tree\n" ); |
217 | return -EINVAL; |
218 | } |
219 | |
220 | if (of_property_read_bool(node, "autorepeat" )) |
221 | __set_bit(EV_REP, capdev->input->evbit); |
222 | |
223 | capdev->num_btn = of_property_count_u32_elems(node, "linux,keymap" ); |
224 | if (capdev->num_btn > MAX_NUM_OF_BUTTONS) |
225 | capdev->num_btn = MAX_NUM_OF_BUTTONS; |
226 | |
227 | err = of_property_read_u32_array(node, "linux,keycodes" , |
228 | capdev->keycodes, |
229 | capdev->num_btn); |
230 | if (err) { |
231 | dev_err(dev, |
232 | "failed to read linux,keycode property: %d\n" , err); |
233 | return err; |
234 | } |
235 | |
236 | for (i = 0; i < capdev->num_btn; i++) |
237 | __set_bit(capdev->keycodes[i], capdev->input->keybit); |
238 | |
239 | capdev->input->keycode = capdev->keycodes; |
240 | capdev->input->keycodesize = sizeof(capdev->keycodes[0]); |
241 | capdev->input->keycodemax = capdev->num_btn; |
242 | |
243 | err = input_register_device(capdev->input); |
244 | if (err) |
245 | return err; |
246 | |
247 | err = devm_request_threaded_irq(dev, client->irq, |
248 | NULL, atmel_captouch_isr, |
249 | IRQF_ONESHOT, |
250 | "atmel_captouch" , capdev); |
251 | if (err) { |
252 | dev_err(dev, "failed to request irq %d: %d\n" , |
253 | client->irq, err); |
254 | return err; |
255 | } |
256 | |
257 | return 0; |
258 | } |
259 | |
260 | #ifdef CONFIG_OF |
261 | static const struct of_device_id atmel_captouch_of_id[] = { |
262 | { |
263 | .compatible = "atmel,captouch" , |
264 | }, |
265 | { /* sentinel */ } |
266 | }; |
267 | MODULE_DEVICE_TABLE(of, atmel_captouch_of_id); |
268 | #endif |
269 | |
270 | static const struct i2c_device_id atmel_captouch_id[] = { |
271 | { "atmel_captouch" , 0 }, |
272 | { } |
273 | }; |
274 | MODULE_DEVICE_TABLE(i2c, atmel_captouch_id); |
275 | |
276 | static struct i2c_driver atmel_captouch_driver = { |
277 | .probe = atmel_captouch_probe, |
278 | .id_table = atmel_captouch_id, |
279 | .driver = { |
280 | .name = "atmel_captouch" , |
281 | .of_match_table = of_match_ptr(atmel_captouch_of_id), |
282 | }, |
283 | }; |
284 | module_i2c_driver(atmel_captouch_driver); |
285 | |
286 | /* Module information */ |
287 | MODULE_AUTHOR("Hung-yu Wu <hywu@google.com>" ); |
288 | MODULE_DESCRIPTION("Atmel ATmegaXX Capacitance Touch Sensor I2C Driver" ); |
289 | MODULE_LICENSE("GPL v2" ); |
290 | |