2 * ChromeOS EC keyboard driver
4 * Copyright (C) 2012 Google, Inc
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.
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.
15 * This driver uses the Chrome OS EC byte-level message-based protocol for
16 * communicating the keyboard state (which keys are pressed) from a keyboard EC
17 * to the AP over some bus (such as i2c, lpc, spi). The EC does debouncing,
18 * but everything else (including deghosting) is done here. The main
19 * motivation for this is to keep the EC firmware as simple as possible, since
20 * it cannot be easily upgraded and EC flash/IRAM space is relatively
24 #include <linux/module.h>
25 #include <linux/bitops.h>
26 #include <linux/i2c.h>
27 #include <linux/input.h>
28 #include <linux/interrupt.h>
29 #include <linux/kernel.h>
30 #include <linux/platform_device.h>
31 #include <linux/slab.h>
32 #include <linux/input/matrix_keypad.h>
33 #include <linux/mfd/cros_ec.h>
34 #include <linux/mfd/cros_ec_commands.h>
37 * @rows: Number of rows in the keypad
38 * @cols: Number of columns in the keypad
39 * @row_shift: log2 or number of rows, rounded up
40 * @keymap_data: Matrix keymap data used to convert to keyscan values
41 * @ghost_filter: true to enable the matrix key-ghosting filter
42 * @valid_keys: bitmap of existing keys for each matrix column
43 * @old_kb_state: bitmap of keys pressed last scan
44 * @dev: Device pointer
46 * @ec: Top level ChromeOS device to use to talk to EC
52 const struct matrix_keymap_data *keymap_data;
55 uint8_t *old_kb_state;
58 struct input_dev *idev;
59 struct cros_ec_device *ec;
64 * Returns true when there is at least one combination of pressed keys that
65 * results in ghosting.
67 static bool cros_ec_keyb_has_ghosting(struct cros_ec_keyb *ckdev, uint8_t *buf)
69 int col1, col2, buf1, buf2;
70 struct device *dev = ckdev->dev;
71 uint8_t *valid_keys = ckdev->valid_keys;
74 * Ghosting happens if for any pressed key X there are other keys
75 * pressed both in the same row and column of X as, for instance,
76 * in the following diagram:
83 * In this case only X, Y, and Z are pressed, but g appears to be
84 * pressed too (see Wikipedia).
86 for (col1 = 0; col1 < ckdev->cols; col1++) {
87 buf1 = buf[col1] & valid_keys[col1];
88 for (col2 = col1 + 1; col2 < ckdev->cols; col2++) {
89 buf2 = buf[col2] & valid_keys[col2];
90 if (hweight8(buf1 & buf2) > 1) {
91 dev_dbg(dev, "ghost found at: B[%02d]:0x%02x & B[%02d]:0x%02x",
92 col1, buf1, col2, buf2);
103 * Compares the new keyboard state to the old one and produces key
104 * press/release events accordingly. The keyboard state is 13 bytes (one byte
107 static void cros_ec_keyb_process(struct cros_ec_keyb *ckdev,
108 uint8_t *kb_state, int len)
110 struct input_dev *idev = ckdev->idev;
118 if (ckdev->ghost_filter && cros_ec_keyb_has_ghosting(ckdev, kb_state)) {
120 * Simple-minded solution: ignore this state. The obvious
121 * improvement is to only ignore changes to keys involved in
122 * the ghosting, but process the other changes.
124 dev_dbg(ckdev->dev, "ghosting found\n");
128 for (col = 0; col < ckdev->cols; col++) {
129 for (row = 0; row < ckdev->rows; row++) {
130 int pos = MATRIX_SCAN_CODE(row, col, ckdev->row_shift);
131 const unsigned short *keycodes = idev->keycode;
133 new_state = kb_state[col] & (1 << row);
134 old_state = ckdev->old_kb_state[col] & (1 << row);
135 if (new_state != old_state) {
137 "changed: [r%d c%d]: byte %02x\n",
138 row, col, new_state);
140 input_report_key(idev, keycodes[pos],
144 ckdev->old_kb_state[col] = kb_state[col];
146 input_sync(ckdev->idev);
149 static int cros_ec_keyb_get_state(struct cros_ec_keyb *ckdev, uint8_t *kb_state)
151 struct cros_ec_command msg = {
153 .command = EC_CMD_MKBP_STATE,
157 .insize = ckdev->cols,
160 return ckdev->ec->cmd_xfer(ckdev->ec, &msg);
163 static irqreturn_t cros_ec_keyb_irq(int irq, void *data)
165 struct cros_ec_keyb *ckdev = data;
166 struct cros_ec_device *ec = ckdev->ec;
168 uint8_t kb_state[ckdev->cols];
170 if (device_may_wakeup(ec->dev))
171 pm_wakeup_event(ec->dev, 0);
173 ret = cros_ec_keyb_get_state(ckdev, kb_state);
175 cros_ec_keyb_process(ckdev, kb_state, ret);
177 dev_err(ec->dev, "failed to get keyboard state: %d\n", ret);
182 static int cros_ec_keyb_open(struct input_dev *dev)
184 struct cros_ec_keyb *ckdev = input_get_drvdata(dev);
185 struct cros_ec_device *ec = ckdev->ec;
187 return request_threaded_irq(ec->irq, NULL, cros_ec_keyb_irq,
188 IRQF_TRIGGER_LOW | IRQF_ONESHOT,
189 "cros_ec_keyb", ckdev);
192 static void cros_ec_keyb_close(struct input_dev *dev)
194 struct cros_ec_keyb *ckdev = input_get_drvdata(dev);
195 struct cros_ec_device *ec = ckdev->ec;
197 free_irq(ec->irq, ckdev);
201 * Walks keycodes flipping bit in buffer COLUMNS deep where bit is ROW. Used by
202 * ghosting logic to ignore NULL or virtual keys.
204 static void cros_ec_keyb_compute_valid_keys(struct cros_ec_keyb *ckdev)
207 int row_shift = ckdev->row_shift;
208 unsigned short *keymap = ckdev->idev->keycode;
211 BUG_ON(ckdev->idev->keycodesize != sizeof(*keymap));
213 for (col = 0; col < ckdev->cols; col++) {
214 for (row = 0; row < ckdev->rows; row++) {
215 code = keymap[MATRIX_SCAN_CODE(row, col, row_shift)];
216 if (code && (code != KEY_BATTERY))
217 ckdev->valid_keys[col] |= 1 << row;
219 dev_dbg(ckdev->dev, "valid_keys[%02d] = 0x%02x\n",
220 col, ckdev->valid_keys[col]);
224 static int cros_ec_keyb_probe(struct platform_device *pdev)
226 struct cros_ec_device *ec = dev_get_drvdata(pdev->dev.parent);
227 struct device *dev = ec->dev;
228 struct cros_ec_keyb *ckdev;
229 struct input_dev *idev;
230 struct device_node *np;
233 np = pdev->dev.of_node;
237 ckdev = devm_kzalloc(&pdev->dev, sizeof(*ckdev), GFP_KERNEL);
240 err = matrix_keypad_parse_of_params(&pdev->dev, &ckdev->rows,
245 ckdev->valid_keys = devm_kzalloc(&pdev->dev, ckdev->cols, GFP_KERNEL);
246 if (!ckdev->valid_keys)
249 ckdev->old_kb_state = devm_kzalloc(&pdev->dev, ckdev->cols, GFP_KERNEL);
250 if (!ckdev->old_kb_state)
253 idev = devm_input_allocate_device(&pdev->dev);
258 dev_err(dev, "no EC IRQ specified\n");
264 dev_set_drvdata(&pdev->dev, ckdev);
266 idev->name = ec->ec_name;
267 idev->phys = ec->phys_name;
268 __set_bit(EV_REP, idev->evbit);
270 idev->id.bustype = BUS_VIRTUAL;
271 idev->id.version = 1;
272 idev->id.product = 0;
273 idev->dev.parent = &pdev->dev;
274 idev->open = cros_ec_keyb_open;
275 idev->close = cros_ec_keyb_close;
277 ckdev->ghost_filter = of_property_read_bool(np,
278 "google,needs-ghost-filter");
280 err = matrix_keypad_build_keymap(NULL, NULL, ckdev->rows, ckdev->cols,
283 dev_err(dev, "cannot build key matrix\n");
287 ckdev->row_shift = get_count_order(ckdev->cols);
289 input_set_capability(idev, EV_MSC, MSC_SCAN);
290 input_set_drvdata(idev, ckdev);
292 cros_ec_keyb_compute_valid_keys(ckdev);
294 err = input_register_device(ckdev->idev);
296 dev_err(dev, "cannot register input device\n");
303 #ifdef CONFIG_PM_SLEEP
304 /* Clear any keys in the buffer */
305 static void cros_ec_keyb_clear_keyboard(struct cros_ec_keyb *ckdev)
307 uint8_t old_state[ckdev->cols];
308 uint8_t new_state[ckdev->cols];
309 unsigned long duration;
313 * Keep reading until we see that the scan state does not change.
314 * That indicates that we are done.
316 * Assume that the EC keyscan buffer is at most 32 deep.
319 ret = cros_ec_keyb_get_state(ckdev, new_state);
320 for (i = 1; !ret && i < 32; i++) {
321 memcpy(old_state, new_state, sizeof(old_state));
322 ret = cros_ec_keyb_get_state(ckdev, new_state);
323 if (0 == memcmp(old_state, new_state, sizeof(old_state)))
326 duration = jiffies - duration;
327 dev_info(ckdev->dev, "Discarded %d keyscan(s) in %dus\n", i,
328 jiffies_to_usecs(duration));
331 static int cros_ec_keyb_resume(struct device *dev)
333 struct cros_ec_keyb *ckdev = dev_get_drvdata(dev);
336 * When the EC is not a wake source, then it could not have caused the
337 * resume, so we clear the EC's key scan buffer. If the EC was a
338 * wake source (e.g. the lid is open and the user might press a key to
339 * wake) then the key scan buffer should be preserved.
341 if (ckdev->ec->was_wake_device)
342 cros_ec_keyb_clear_keyboard(ckdev);
349 static SIMPLE_DEV_PM_OPS(cros_ec_keyb_pm_ops, NULL, cros_ec_keyb_resume);
351 static struct platform_driver cros_ec_keyb_driver = {
352 .probe = cros_ec_keyb_probe,
354 .name = "cros-ec-keyb",
355 .pm = &cros_ec_keyb_pm_ops,
359 module_platform_driver(cros_ec_keyb_driver);
361 MODULE_LICENSE("GPL");
362 MODULE_DESCRIPTION("ChromeOS EC keyboard driver");
363 MODULE_ALIAS("platform:cros-ec-keyb");