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/notifier.h> 31 #include <linux/platform_device.h> 32 #include <linux/slab.h> 33 #include <linux/input/matrix_keypad.h> 34 #include <linux/mfd/cros_ec.h> 35 #include <linux/mfd/cros_ec_commands.h> 36 37 /* 38 * @rows: Number of rows in the keypad 39 * @cols: Number of columns in the keypad 40 * @row_shift: log2 or number of rows, rounded up 41 * @keymap_data: Matrix keymap data used to convert to keyscan values 42 * @ghost_filter: true to enable the matrix key-ghosting filter 43 * @valid_keys: bitmap of existing keys for each matrix column 44 * @old_kb_state: bitmap of keys pressed last scan 45 * @dev: Device pointer 46 * @idev: Input device 47 * @ec: Top level ChromeOS device to use to talk to EC 48 * @notifier: interrupt event notifier for transport devices 49 */ 50 struct cros_ec_keyb { 51 unsigned int rows; 52 unsigned int cols; 53 int row_shift; 54 const struct matrix_keymap_data *keymap_data; 55 bool ghost_filter; 56 uint8_t *valid_keys; 57 uint8_t *old_kb_state; 58 59 struct device *dev; 60 struct input_dev *idev; 61 struct cros_ec_device *ec; 62 struct notifier_block notifier; 63 }; 64 65 66 /* 67 * Returns true when there is at least one combination of pressed keys that 68 * results in ghosting. 69 */ 70 static bool cros_ec_keyb_has_ghosting(struct cros_ec_keyb *ckdev, uint8_t *buf) 71 { 72 int col1, col2, buf1, buf2; 73 struct device *dev = ckdev->dev; 74 uint8_t *valid_keys = ckdev->valid_keys; 75 76 /* 77 * Ghosting happens if for any pressed key X there are other keys 78 * pressed both in the same row and column of X as, for instance, 79 * in the following diagram: 80 * 81 * . . Y . g . 82 * . . . . . . 83 * . . . . . . 84 * . . X . Z . 85 * 86 * In this case only X, Y, and Z are pressed, but g appears to be 87 * pressed too (see Wikipedia). 88 */ 89 for (col1 = 0; col1 < ckdev->cols; col1++) { 90 buf1 = buf[col1] & valid_keys[col1]; 91 for (col2 = col1 + 1; col2 < ckdev->cols; col2++) { 92 buf2 = buf[col2] & valid_keys[col2]; 93 if (hweight8(buf1 & buf2) > 1) { 94 dev_dbg(dev, "ghost found at: B[%02d]:0x%02x & B[%02d]:0x%02x", 95 col1, buf1, col2, buf2); 96 return true; 97 } 98 } 99 } 100 101 return false; 102 } 103 104 105 /* 106 * Compares the new keyboard state to the old one and produces key 107 * press/release events accordingly. The keyboard state is 13 bytes (one byte 108 * per column) 109 */ 110 static void cros_ec_keyb_process(struct cros_ec_keyb *ckdev, 111 uint8_t *kb_state, int len) 112 { 113 struct input_dev *idev = ckdev->idev; 114 int col, row; 115 int new_state; 116 int old_state; 117 int num_cols; 118 119 num_cols = len; 120 121 if (ckdev->ghost_filter && cros_ec_keyb_has_ghosting(ckdev, kb_state)) { 122 /* 123 * Simple-minded solution: ignore this state. The obvious 124 * improvement is to only ignore changes to keys involved in 125 * the ghosting, but process the other changes. 126 */ 127 dev_dbg(ckdev->dev, "ghosting found\n"); 128 return; 129 } 130 131 for (col = 0; col < ckdev->cols; col++) { 132 for (row = 0; row < ckdev->rows; row++) { 133 int pos = MATRIX_SCAN_CODE(row, col, ckdev->row_shift); 134 const unsigned short *keycodes = idev->keycode; 135 136 new_state = kb_state[col] & (1 << row); 137 old_state = ckdev->old_kb_state[col] & (1 << row); 138 if (new_state != old_state) { 139 dev_dbg(ckdev->dev, 140 "changed: [r%d c%d]: byte %02x\n", 141 row, col, new_state); 142 143 input_report_key(idev, keycodes[pos], 144 new_state); 145 } 146 } 147 ckdev->old_kb_state[col] = kb_state[col]; 148 } 149 input_sync(ckdev->idev); 150 } 151 152 static int cros_ec_keyb_open(struct input_dev *dev) 153 { 154 struct cros_ec_keyb *ckdev = input_get_drvdata(dev); 155 156 return blocking_notifier_chain_register(&ckdev->ec->event_notifier, 157 &ckdev->notifier); 158 } 159 160 static void cros_ec_keyb_close(struct input_dev *dev) 161 { 162 struct cros_ec_keyb *ckdev = input_get_drvdata(dev); 163 164 blocking_notifier_chain_unregister(&ckdev->ec->event_notifier, 165 &ckdev->notifier); 166 } 167 168 static int cros_ec_keyb_work(struct notifier_block *nb, 169 unsigned long queued_during_suspend, void *_notify) 170 { 171 struct cros_ec_keyb *ckdev = container_of(nb, struct cros_ec_keyb, 172 notifier); 173 174 if (ckdev->ec->event_data.event_type != EC_MKBP_EVENT_KEY_MATRIX) 175 return NOTIFY_DONE; 176 /* 177 * If EC is not the wake source, discard key state changes during 178 * suspend. 179 */ 180 if (queued_during_suspend) 181 return NOTIFY_OK; 182 if (ckdev->ec->event_size != ckdev->cols) { 183 dev_err(ckdev->dev, 184 "Discarded incomplete key matrix event.\n"); 185 return NOTIFY_OK; 186 } 187 cros_ec_keyb_process(ckdev, ckdev->ec->event_data.data.key_matrix, 188 ckdev->ec->event_size); 189 return NOTIFY_OK; 190 } 191 192 /* 193 * Walks keycodes flipping bit in buffer COLUMNS deep where bit is ROW. Used by 194 * ghosting logic to ignore NULL or virtual keys. 195 */ 196 static void cros_ec_keyb_compute_valid_keys(struct cros_ec_keyb *ckdev) 197 { 198 int row, col; 199 int row_shift = ckdev->row_shift; 200 unsigned short *keymap = ckdev->idev->keycode; 201 unsigned short code; 202 203 BUG_ON(ckdev->idev->keycodesize != sizeof(*keymap)); 204 205 for (col = 0; col < ckdev->cols; col++) { 206 for (row = 0; row < ckdev->rows; row++) { 207 code = keymap[MATRIX_SCAN_CODE(row, col, row_shift)]; 208 if (code && (code != KEY_BATTERY)) 209 ckdev->valid_keys[col] |= 1 << row; 210 } 211 dev_dbg(ckdev->dev, "valid_keys[%02d] = 0x%02x\n", 212 col, ckdev->valid_keys[col]); 213 } 214 } 215 216 static int cros_ec_keyb_probe(struct platform_device *pdev) 217 { 218 struct cros_ec_device *ec = dev_get_drvdata(pdev->dev.parent); 219 struct device *dev = &pdev->dev; 220 struct cros_ec_keyb *ckdev; 221 struct input_dev *idev; 222 struct device_node *np; 223 int err; 224 225 np = pdev->dev.of_node; 226 if (!np) 227 return -ENODEV; 228 229 ckdev = devm_kzalloc(dev, sizeof(*ckdev), GFP_KERNEL); 230 if (!ckdev) 231 return -ENOMEM; 232 err = matrix_keypad_parse_of_params(dev, &ckdev->rows, &ckdev->cols); 233 if (err) 234 return err; 235 236 ckdev->valid_keys = devm_kzalloc(dev, ckdev->cols, GFP_KERNEL); 237 if (!ckdev->valid_keys) 238 return -ENOMEM; 239 240 ckdev->old_kb_state = devm_kzalloc(dev, ckdev->cols, GFP_KERNEL); 241 if (!ckdev->old_kb_state) 242 return -ENOMEM; 243 244 idev = devm_input_allocate_device(dev); 245 if (!idev) 246 return -ENOMEM; 247 248 ckdev->ec = ec; 249 ckdev->notifier.notifier_call = cros_ec_keyb_work; 250 ckdev->dev = dev; 251 dev_set_drvdata(dev, ckdev); 252 253 idev->name = CROS_EC_DEV_NAME; 254 idev->phys = ec->phys_name; 255 __set_bit(EV_REP, idev->evbit); 256 257 idev->id.bustype = BUS_VIRTUAL; 258 idev->id.version = 1; 259 idev->id.product = 0; 260 idev->dev.parent = dev; 261 idev->open = cros_ec_keyb_open; 262 idev->close = cros_ec_keyb_close; 263 264 ckdev->ghost_filter = of_property_read_bool(np, 265 "google,needs-ghost-filter"); 266 267 err = matrix_keypad_build_keymap(NULL, NULL, ckdev->rows, ckdev->cols, 268 NULL, idev); 269 if (err) { 270 dev_err(dev, "cannot build key matrix\n"); 271 return err; 272 } 273 274 ckdev->row_shift = get_count_order(ckdev->cols); 275 276 input_set_capability(idev, EV_MSC, MSC_SCAN); 277 input_set_drvdata(idev, ckdev); 278 ckdev->idev = idev; 279 cros_ec_keyb_compute_valid_keys(ckdev); 280 281 err = input_register_device(ckdev->idev); 282 if (err) { 283 dev_err(dev, "cannot register input device\n"); 284 return err; 285 } 286 287 return 0; 288 } 289 290 #ifdef CONFIG_OF 291 static const struct of_device_id cros_ec_keyb_of_match[] = { 292 { .compatible = "google,cros-ec-keyb" }, 293 {}, 294 }; 295 MODULE_DEVICE_TABLE(of, cros_ec_keyb_of_match); 296 #endif 297 298 static struct platform_driver cros_ec_keyb_driver = { 299 .probe = cros_ec_keyb_probe, 300 .driver = { 301 .name = "cros-ec-keyb", 302 .of_match_table = of_match_ptr(cros_ec_keyb_of_match), 303 }, 304 }; 305 306 module_platform_driver(cros_ec_keyb_driver); 307 308 MODULE_LICENSE("GPL"); 309 MODULE_DESCRIPTION("ChromeOS EC keyboard driver"); 310 MODULE_ALIAS("platform:cros-ec-keyb"); 311