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 = 0; 152 struct cros_ec_command *msg; 153 154 msg = kmalloc(sizeof(*msg) + ckdev->cols, GFP_KERNEL); 155 if (!msg) 156 return -ENOMEM; 157 158 msg->version = 0; 159 msg->command = EC_CMD_MKBP_STATE; 160 msg->insize = ckdev->cols; 161 msg->outsize = 0; 162 163 ret = cros_ec_cmd_xfer(ckdev->ec, msg); 164 if (ret < 0) { 165 dev_err(ckdev->dev, "Error transferring EC message %d\n", ret); 166 goto exit; 167 } 168 169 memcpy(kb_state, msg->data, ckdev->cols); 170 exit: 171 kfree(msg); 172 return ret; 173 } 174 175 static irqreturn_t cros_ec_keyb_irq(int irq, void *data) 176 { 177 struct cros_ec_keyb *ckdev = data; 178 struct cros_ec_device *ec = ckdev->ec; 179 int ret; 180 uint8_t kb_state[ckdev->cols]; 181 182 if (device_may_wakeup(ec->dev)) 183 pm_wakeup_event(ec->dev, 0); 184 185 ret = cros_ec_keyb_get_state(ckdev, kb_state); 186 if (ret >= 0) 187 cros_ec_keyb_process(ckdev, kb_state, ret); 188 else 189 dev_err(ec->dev, "failed to get keyboard state: %d\n", ret); 190 191 return IRQ_HANDLED; 192 } 193 194 static int cros_ec_keyb_open(struct input_dev *dev) 195 { 196 struct cros_ec_keyb *ckdev = input_get_drvdata(dev); 197 struct cros_ec_device *ec = ckdev->ec; 198 199 return request_threaded_irq(ec->irq, NULL, cros_ec_keyb_irq, 200 IRQF_TRIGGER_LOW | IRQF_ONESHOT, 201 "cros_ec_keyb", ckdev); 202 } 203 204 static void cros_ec_keyb_close(struct input_dev *dev) 205 { 206 struct cros_ec_keyb *ckdev = input_get_drvdata(dev); 207 struct cros_ec_device *ec = ckdev->ec; 208 209 free_irq(ec->irq, ckdev); 210 } 211 212 /* 213 * Walks keycodes flipping bit in buffer COLUMNS deep where bit is ROW. Used by 214 * ghosting logic to ignore NULL or virtual keys. 215 */ 216 static void cros_ec_keyb_compute_valid_keys(struct cros_ec_keyb *ckdev) 217 { 218 int row, col; 219 int row_shift = ckdev->row_shift; 220 unsigned short *keymap = ckdev->idev->keycode; 221 unsigned short code; 222 223 BUG_ON(ckdev->idev->keycodesize != sizeof(*keymap)); 224 225 for (col = 0; col < ckdev->cols; col++) { 226 for (row = 0; row < ckdev->rows; row++) { 227 code = keymap[MATRIX_SCAN_CODE(row, col, row_shift)]; 228 if (code && (code != KEY_BATTERY)) 229 ckdev->valid_keys[col] |= 1 << row; 230 } 231 dev_dbg(ckdev->dev, "valid_keys[%02d] = 0x%02x\n", 232 col, ckdev->valid_keys[col]); 233 } 234 } 235 236 static int cros_ec_keyb_probe(struct platform_device *pdev) 237 { 238 struct cros_ec_device *ec = dev_get_drvdata(pdev->dev.parent); 239 struct device *dev = ec->dev; 240 struct cros_ec_keyb *ckdev; 241 struct input_dev *idev; 242 struct device_node *np; 243 int err; 244 245 np = pdev->dev.of_node; 246 if (!np) 247 return -ENODEV; 248 249 ckdev = devm_kzalloc(&pdev->dev, sizeof(*ckdev), GFP_KERNEL); 250 if (!ckdev) 251 return -ENOMEM; 252 err = matrix_keypad_parse_of_params(&pdev->dev, &ckdev->rows, 253 &ckdev->cols); 254 if (err) 255 return err; 256 257 ckdev->valid_keys = devm_kzalloc(&pdev->dev, ckdev->cols, GFP_KERNEL); 258 if (!ckdev->valid_keys) 259 return -ENOMEM; 260 261 ckdev->old_kb_state = devm_kzalloc(&pdev->dev, ckdev->cols, GFP_KERNEL); 262 if (!ckdev->old_kb_state) 263 return -ENOMEM; 264 265 idev = devm_input_allocate_device(&pdev->dev); 266 if (!idev) 267 return -ENOMEM; 268 269 if (!ec->irq) { 270 dev_err(dev, "no EC IRQ specified\n"); 271 return -EINVAL; 272 } 273 274 ckdev->ec = ec; 275 ckdev->dev = dev; 276 dev_set_drvdata(&pdev->dev, ckdev); 277 278 idev->name = CROS_EC_DEV_NAME; 279 idev->phys = ec->phys_name; 280 __set_bit(EV_REP, idev->evbit); 281 282 idev->id.bustype = BUS_VIRTUAL; 283 idev->id.version = 1; 284 idev->id.product = 0; 285 idev->dev.parent = &pdev->dev; 286 idev->open = cros_ec_keyb_open; 287 idev->close = cros_ec_keyb_close; 288 289 ckdev->ghost_filter = of_property_read_bool(np, 290 "google,needs-ghost-filter"); 291 292 err = matrix_keypad_build_keymap(NULL, NULL, ckdev->rows, ckdev->cols, 293 NULL, idev); 294 if (err) { 295 dev_err(dev, "cannot build key matrix\n"); 296 return err; 297 } 298 299 ckdev->row_shift = get_count_order(ckdev->cols); 300 301 input_set_capability(idev, EV_MSC, MSC_SCAN); 302 input_set_drvdata(idev, ckdev); 303 ckdev->idev = idev; 304 cros_ec_keyb_compute_valid_keys(ckdev); 305 306 err = input_register_device(ckdev->idev); 307 if (err) { 308 dev_err(dev, "cannot register input device\n"); 309 return err; 310 } 311 312 return 0; 313 } 314 315 #ifdef CONFIG_PM_SLEEP 316 /* Clear any keys in the buffer */ 317 static void cros_ec_keyb_clear_keyboard(struct cros_ec_keyb *ckdev) 318 { 319 uint8_t old_state[ckdev->cols]; 320 uint8_t new_state[ckdev->cols]; 321 unsigned long duration; 322 int i, ret; 323 324 /* 325 * Keep reading until we see that the scan state does not change. 326 * That indicates that we are done. 327 * 328 * Assume that the EC keyscan buffer is at most 32 deep. 329 */ 330 duration = jiffies; 331 ret = cros_ec_keyb_get_state(ckdev, new_state); 332 for (i = 1; !ret && i < 32; i++) { 333 memcpy(old_state, new_state, sizeof(old_state)); 334 ret = cros_ec_keyb_get_state(ckdev, new_state); 335 if (0 == memcmp(old_state, new_state, sizeof(old_state))) 336 break; 337 } 338 duration = jiffies - duration; 339 dev_info(ckdev->dev, "Discarded %d keyscan(s) in %dus\n", i, 340 jiffies_to_usecs(duration)); 341 } 342 343 static int cros_ec_keyb_resume(struct device *dev) 344 { 345 struct cros_ec_keyb *ckdev = dev_get_drvdata(dev); 346 347 /* 348 * When the EC is not a wake source, then it could not have caused the 349 * resume, so we clear the EC's key scan buffer. If the EC was a 350 * wake source (e.g. the lid is open and the user might press a key to 351 * wake) then the key scan buffer should be preserved. 352 */ 353 if (!ckdev->ec->was_wake_device) 354 cros_ec_keyb_clear_keyboard(ckdev); 355 356 return 0; 357 } 358 359 #endif 360 361 static SIMPLE_DEV_PM_OPS(cros_ec_keyb_pm_ops, NULL, cros_ec_keyb_resume); 362 363 #ifdef CONFIG_OF 364 static const struct of_device_id cros_ec_keyb_of_match[] = { 365 { .compatible = "google,cros-ec-keyb" }, 366 {}, 367 }; 368 MODULE_DEVICE_TABLE(of, cros_ec_keyb_of_match); 369 #endif 370 371 static struct platform_driver cros_ec_keyb_driver = { 372 .probe = cros_ec_keyb_probe, 373 .driver = { 374 .name = "cros-ec-keyb", 375 .of_match_table = of_match_ptr(cros_ec_keyb_of_match), 376 .pm = &cros_ec_keyb_pm_ops, 377 }, 378 }; 379 380 module_platform_driver(cros_ec_keyb_driver); 381 382 MODULE_LICENSE("GPL"); 383 MODULE_DESCRIPTION("ChromeOS EC keyboard driver"); 384 MODULE_ALIAS("platform:cros-ec-keyb"); 385