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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
32#define MAX_NUM_OF_BUTTONS 8
33
34
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
62
63
64
65
66
67
68struct 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
79
80
81
82
83static 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
125
126
127
128static 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
157out:
158 return IRQ_HANDLED;
159}
160
161
162
163
164static 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;
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
253static const struct of_device_id atmel_captouch_of_id[] = {
254 {
255 .compatible = "atmel,captouch",
256 },
257 { }
258};
259MODULE_DEVICE_TABLE(of, atmel_captouch_of_id);
260#endif
261
262static const struct i2c_device_id atmel_captouch_id[] = {
263 { "atmel_captouch", 0 },
264 { }
265};
266MODULE_DEVICE_TABLE(i2c, atmel_captouch_id);
267
268static 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};
276module_i2c_driver(atmel_captouch_driver);
277
278
279MODULE_AUTHOR("Hung-yu Wu <hywu@google.com>");
280MODULE_DESCRIPTION("Atmel ATmegaXX Capacitance Touch Sensor I2C Driver");
281MODULE_LICENSE("GPL v2");
282
