1 /* 2 * ChromeOS EC keyboard driver 3 * 4 * Copyright (C) 2012 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 * 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 21 * expensive. 22 */ 23 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> 35 36 /* 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 45 * @idev: Input device 46 * @ec: Top level ChromeOS device to use to talk to EC 47 */ 48 struct cros_ec_keyb { 49 unsigned int rows; 50 unsigned int cols; 51 int row_shift; 52 const struct matrix_keymap_data *keymap_data; 53 bool ghost_filter; 54 uint8_t *valid_keys; 55 uint8_t *old_kb_state; 56 57 struct device *dev; 58 struct input_dev *idev; 59 struct cros_ec_device *ec; 60 }; 61 62 63 /* 64 * Returns true when there is at least one combination of pressed keys that 65 * results in ghosting. 66 */ 67 static bool cros_ec_keyb_has_ghosting(struct cros_ec_keyb *ckdev, uint8_t *buf) 68 { 69 int col1, col2, buf1, buf2; 70 struct device *dev = ckdev->dev; 71 uint8_t *valid_keys = ckdev->valid_keys; 72 73 /* 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: 77 * 78 * . . Y . g . 79 * . . . . . . 80 * . . . . . . 81 * . . X . Z . 82 * 83 * In this case only X, Y, and Z are pressed, but g appears to be 84 * pressed too (see Wikipedia). 85 */ 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); 93 return true; 94 } 95 } 96 } 97 98 return false; 99 } 100 101 102 /* 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 105 * per column) 106 */ 107 static void cros_ec_keyb_process(struct cros_ec_keyb *ckdev, 108 uint8_t *kb_state, int len) 109 { 110 struct input_dev *idev = ckdev->idev; 111 int col, row; 112 int new_state; 113 int old_state; 114 int num_cols; 115 116 num_cols = len; 117 118 if (ckdev->ghost_filter && cros_ec_keyb_has_ghosting(ckdev, kb_state)) { 119 /* 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. 123 */ 124 dev_dbg(ckdev->dev, "ghosting found\n"); 125 return; 126 } 127 128 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; 132 133 new_state = kb_state[col] & (1 << row); 134 old_state = ckdev->old_kb_state[col] & (1 << row); 135 if (new_state != old_state) { 136 dev_dbg(ckdev->dev, 137 "changed: [r%d c%d]: byte %02x\n", 138 row, col, new_state); 139 140 input_report_key(idev, keycodes[pos], 141 new_state); 142 } 143 } 144 ckdev->old_kb_state[col] = kb_state[col]; 145 } 146 input_sync(ckdev->idev); 147 } 148 149 static int cros_ec_keyb_get_state(struct cros_ec_keyb *ckdev, uint8_t *kb_state) 150 { 151 int ret; 152 struct cros_ec_command msg = { 153 .command = EC_CMD_MKBP_STATE, 154 .insize = ckdev->cols, 155 }; 156 157 ret = cros_ec_cmd_xfer(ckdev->ec, &msg); 158 if (ret < 0) 159 return ret; 160 161 memcpy(kb_state, msg.indata, ckdev->cols); 162 163 return 0; 164 } 165 166 static irqreturn_t cros_ec_keyb_irq(int irq, void *data) 167 { 168 struct cros_ec_keyb *ckdev = data; 169 struct cros_ec_device *ec = ckdev->ec; 170 int ret; 171 uint8_t kb_state[ckdev->cols]; 172 173 if (device_may_wakeup(ec->dev)) 174 pm_wakeup_event(ec->dev, 0); 175 176 ret = cros_ec_keyb_get_state(ckdev, kb_state); 177 if (ret >= 0) 178 cros_ec_keyb_process(ckdev, kb_state, ret); 179 else 180 dev_err(ec->dev, "failed to get keyboard state: %d\n", ret); 181 182 return IRQ_HANDLED; 183 } 184 185 static int cros_ec_keyb_open(struct input_dev *dev) 186 { 187 struct cros_ec_keyb *ckdev = input_get_drvdata(dev); 188 struct cros_ec_device *ec = ckdev->ec; 189 190 return request_threaded_irq(ec->irq, NULL, cros_ec_keyb_irq, 191 IRQF_TRIGGER_LOW | IRQF_ONESHOT, 192 "cros_ec_keyb", ckdev); 193 } 194 195 static void cros_ec_keyb_close(struct input_dev *dev) 196 { 197 struct cros_ec_keyb *ckdev = input_get_drvdata(dev); 198 struct cros_ec_device *ec = ckdev->ec; 199 200 free_irq(ec->irq, ckdev); 201 } 202 203 /* 204 * Walks keycodes flipping bit in buffer COLUMNS deep where bit is ROW. Used by 205 * ghosting logic to ignore NULL or virtual keys. 206 */ 207 static void cros_ec_keyb_compute_valid_keys(struct cros_ec_keyb *ckdev) 208 { 209 int row, col; 210 int row_shift = ckdev->row_shift; 211 unsigned short *keymap = ckdev->idev->keycode; 212 unsigned short code; 213 214 BUG_ON(ckdev->idev->keycodesize != sizeof(*keymap)); 215 216 for (col = 0; col < ckdev->cols; col++) { 217 for (row = 0; row < ckdev->rows; row++) { 218 code = keymap[MATRIX_SCAN_CODE(row, col, row_shift)]; 219 if (code && (code != KEY_BATTERY)) 220 ckdev->valid_keys[col] |= 1 << row; 221 } 222 dev_dbg(ckdev->dev, "valid_keys[%02d] = 0x%02x\n", 223 col, ckdev->valid_keys[col]); 224 } 225 } 226 227 static int cros_ec_keyb_probe(struct platform_device *pdev) 228 { 229 struct cros_ec_device *ec = dev_get_drvdata(pdev->dev.parent); 230 struct device *dev = ec->dev; 231 struct cros_ec_keyb *ckdev; 232 struct input_dev *idev; 233 struct device_node *np; 234 int err; 235 236 np = pdev->dev.of_node; 237 if (!np) 238 return -ENODEV; 239 240 ckdev = devm_kzalloc(&pdev->dev, sizeof(*ckdev), GFP_KERNEL); 241 if (!ckdev) 242 return -ENOMEM; 243 err = matrix_keypad_parse_of_params(&pdev->dev, &ckdev->rows, 244 &ckdev->cols); 245 if (err) 246 return err; 247 248 ckdev->valid_keys = devm_kzalloc(&pdev->dev, ckdev->cols, GFP_KERNEL); 249 if (!ckdev->valid_keys) 250 return -ENOMEM; 251 252 ckdev->old_kb_state = devm_kzalloc(&pdev->dev, ckdev->cols, GFP_KERNEL); 253 if (!ckdev->old_kb_state) 254 return -ENOMEM; 255 256 idev = devm_input_allocate_device(&pdev->dev); 257 if (!idev) 258 return -ENOMEM; 259 260 if (!ec->irq) { 261 dev_err(dev, "no EC IRQ specified\n"); 262 return -EINVAL; 263 } 264 265 ckdev->ec = ec; 266 ckdev->dev = dev; 267 dev_set_drvdata(&pdev->dev, ckdev); 268 269 idev->name = ec->ec_name; 270 idev->phys = ec->phys_name; 271 __set_bit(EV_REP, idev->evbit); 272 273 idev->id.bustype = BUS_VIRTUAL; 274 idev->id.version = 1; 275 idev->id.product = 0; 276 idev->dev.parent = &pdev->dev; 277 idev->open = cros_ec_keyb_open; 278 idev->close = cros_ec_keyb_close; 279 280 ckdev->ghost_filter = of_property_read_bool(np, 281 "google,needs-ghost-filter"); 282 283 err = matrix_keypad_build_keymap(NULL, NULL, ckdev->rows, ckdev->cols, 284 NULL, idev); 285 if (err) { 286 dev_err(dev, "cannot build key matrix\n"); 287 return err; 288 } 289 290 ckdev->row_shift = get_count_order(ckdev->cols); 291 292 input_set_capability(idev, EV_MSC, MSC_SCAN); 293 input_set_drvdata(idev, ckdev); 294 ckdev->idev = idev; 295 cros_ec_keyb_compute_valid_keys(ckdev); 296 297 err = input_register_device(ckdev->idev); 298 if (err) { 299 dev_err(dev, "cannot register input device\n"); 300 return err; 301 } 302 303 return 0; 304 } 305 306 #ifdef CONFIG_PM_SLEEP 307 /* Clear any keys in the buffer */ 308 static void cros_ec_keyb_clear_keyboard(struct cros_ec_keyb *ckdev) 309 { 310 uint8_t old_state[ckdev->cols]; 311 uint8_t new_state[ckdev->cols]; 312 unsigned long duration; 313 int i, ret; 314 315 /* 316 * Keep reading until we see that the scan state does not change. 317 * That indicates that we are done. 318 * 319 * Assume that the EC keyscan buffer is at most 32 deep. 320 */ 321 duration = jiffies; 322 ret = cros_ec_keyb_get_state(ckdev, new_state); 323 for (i = 1; !ret && i < 32; i++) { 324 memcpy(old_state, new_state, sizeof(old_state)); 325 ret = cros_ec_keyb_get_state(ckdev, new_state); 326 if (0 == memcmp(old_state, new_state, sizeof(old_state))) 327 break; 328 } 329 duration = jiffies - duration; 330 dev_info(ckdev->dev, "Discarded %d keyscan(s) in %dus\n", i, 331 jiffies_to_usecs(duration)); 332 } 333 334 static int cros_ec_keyb_resume(struct device *dev) 335 { 336 struct cros_ec_keyb *ckdev = dev_get_drvdata(dev); 337 338 /* 339 * When the EC is not a wake source, then it could not have caused the 340 * resume, so we clear the EC's key scan buffer. If the EC was a 341 * wake source (e.g. the lid is open and the user might press a key to 342 * wake) then the key scan buffer should be preserved. 343 */ 344 if (!ckdev->ec->was_wake_device) 345 cros_ec_keyb_clear_keyboard(ckdev); 346 347 return 0; 348 } 349 350 #endif 351 352 static SIMPLE_DEV_PM_OPS(cros_ec_keyb_pm_ops, NULL, cros_ec_keyb_resume); 353 354 #ifdef CONFIG_OF 355 static const struct of_device_id cros_ec_keyb_of_match[] = { 356 { .compatible = "google,cros-ec-keyb" }, 357 {}, 358 }; 359 MODULE_DEVICE_TABLE(of, cros_ec_keyb_of_match); 360 #endif 361 362 static struct platform_driver cros_ec_keyb_driver = { 363 .probe = cros_ec_keyb_probe, 364 .driver = { 365 .name = "cros-ec-keyb", 366 .of_match_table = of_match_ptr(cros_ec_keyb_of_match), 367 .pm = &cros_ec_keyb_pm_ops, 368 }, 369 }; 370 371 module_platform_driver(cros_ec_keyb_driver); 372 373 MODULE_LICENSE("GPL"); 374 MODULE_DESCRIPTION("ChromeOS EC keyboard driver"); 375 MODULE_ALIAS("platform:cros-ec-keyb"); 376