/* * ChromeOS EC keyboard driver * * Copyright (C) 2012 Google, Inc * * This software is licensed under the terms of the GNU General Public * License version 2, as published by the Free Software Foundation, and * may be copied, distributed, and modified under those terms. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * This driver uses the Chrome OS EC byte-level message-based protocol for * communicating the keyboard state (which keys are pressed) from a keyboard EC * to the AP over some bus (such as i2c, lpc, spi). The EC does debouncing, * but everything else (including deghosting) is done here. The main * motivation for this is to keep the EC firmware as simple as possible, since * it cannot be easily upgraded and EC flash/IRAM space is relatively * expensive. */ #include #include #include #include #include #include #include #include #include #include #include #include /* * @rows: Number of rows in the keypad * @cols: Number of columns in the keypad * @row_shift: log2 or number of rows, rounded up * @keymap_data: Matrix keymap data used to convert to keyscan values * @ghost_filter: true to enable the matrix key-ghosting filter * @valid_keys: bitmap of existing keys for each matrix column * @old_kb_state: bitmap of keys pressed last scan * @dev: Device pointer * @idev: Input device * @ec: Top level ChromeOS device to use to talk to EC * @notifier: interrupt event notifier for transport devices */ struct cros_ec_keyb { unsigned int rows; unsigned int cols; int row_shift; const struct matrix_keymap_data *keymap_data; bool ghost_filter; uint8_t *valid_keys; uint8_t *old_kb_state; struct device *dev; struct input_dev *idev; struct cros_ec_device *ec; struct notifier_block notifier; }; /* * Returns true when there is at least one combination of pressed keys that * results in ghosting. */ static bool cros_ec_keyb_has_ghosting(struct cros_ec_keyb *ckdev, uint8_t *buf) { int col1, col2, buf1, buf2; struct device *dev = ckdev->dev; uint8_t *valid_keys = ckdev->valid_keys; /* * Ghosting happens if for any pressed key X there are other keys * pressed both in the same row and column of X as, for instance, * in the following diagram: * * . . Y . g . * . . . . . . * . . . . . . * . . X . Z . * * In this case only X, Y, and Z are pressed, but g appears to be * pressed too (see Wikipedia). */ for (col1 = 0; col1 < ckdev->cols; col1++) { buf1 = buf[col1] & valid_keys[col1]; for (col2 = col1 + 1; col2 < ckdev->cols; col2++) { buf2 = buf[col2] & valid_keys[col2]; if (hweight8(buf1 & buf2) > 1) { dev_dbg(dev, "ghost found at: B[%02d]:0x%02x & B[%02d]:0x%02x", col1, buf1, col2, buf2); return true; } } } return false; } /* * Compares the new keyboard state to the old one and produces key * press/release events accordingly. The keyboard state is 13 bytes (one byte * per column) */ static void cros_ec_keyb_process(struct cros_ec_keyb *ckdev, uint8_t *kb_state, int len) { struct input_dev *idev = ckdev->idev; int col, row; int new_state; int old_state; int num_cols; num_cols = len; if (ckdev->ghost_filter && cros_ec_keyb_has_ghosting(ckdev, kb_state)) { /* * Simple-minded solution: ignore this state. The obvious * improvement is to only ignore changes to keys involved in * the ghosting, but process the other changes. */ dev_dbg(ckdev->dev, "ghosting found\n"); return; } for (col = 0; col < ckdev->cols; col++) { for (row = 0; row < ckdev->rows; row++) { int pos = MATRIX_SCAN_CODE(row, col, ckdev->row_shift); const unsigned short *keycodes = idev->keycode; new_state = kb_state[col] & (1 << row); old_state = ckdev->old_kb_state[col] & (1 << row); if (new_state != old_state) { dev_dbg(ckdev->dev, "changed: [r%d c%d]: byte %02x\n", row, col, new_state); input_report_key(idev, keycodes[pos], new_state); } } ckdev->old_kb_state[col] = kb_state[col]; } input_sync(ckdev->idev); } static int cros_ec_keyb_open(struct input_dev *dev) { struct cros_ec_keyb *ckdev = input_get_drvdata(dev); return blocking_notifier_chain_register(&ckdev->ec->event_notifier, &ckdev->notifier); } static void cros_ec_keyb_close(struct input_dev *dev) { struct cros_ec_keyb *ckdev = input_get_drvdata(dev); blocking_notifier_chain_unregister(&ckdev->ec->event_notifier, &ckdev->notifier); } static int cros_ec_keyb_work(struct notifier_block *nb, unsigned long queued_during_suspend, void *_notify) { struct cros_ec_keyb *ckdev = container_of(nb, struct cros_ec_keyb, notifier); if (ckdev->ec->event_data.event_type != EC_MKBP_EVENT_KEY_MATRIX) return NOTIFY_DONE; /* * If EC is not the wake source, discard key state changes during * suspend. */ if (queued_during_suspend) return NOTIFY_OK; if (ckdev->ec->event_size != ckdev->cols) { dev_err(ckdev->dev, "Discarded incomplete key matrix event.\n"); return NOTIFY_OK; } cros_ec_keyb_process(ckdev, ckdev->ec->event_data.data.key_matrix, ckdev->ec->event_size); return NOTIFY_OK; } /* * Walks keycodes flipping bit in buffer COLUMNS deep where bit is ROW. Used by * ghosting logic to ignore NULL or virtual keys. */ static void cros_ec_keyb_compute_valid_keys(struct cros_ec_keyb *ckdev) { int row, col; int row_shift = ckdev->row_shift; unsigned short *keymap = ckdev->idev->keycode; unsigned short code; BUG_ON(ckdev->idev->keycodesize != sizeof(*keymap)); for (col = 0; col < ckdev->cols; col++) { for (row = 0; row < ckdev->rows; row++) { code = keymap[MATRIX_SCAN_CODE(row, col, row_shift)]; if (code && (code != KEY_BATTERY)) ckdev->valid_keys[col] |= 1 << row; } dev_dbg(ckdev->dev, "valid_keys[%02d] = 0x%02x\n", col, ckdev->valid_keys[col]); } } static int cros_ec_keyb_probe(struct platform_device *pdev) { struct cros_ec_device *ec = dev_get_drvdata(pdev->dev.parent); struct device *dev = &pdev->dev; struct cros_ec_keyb *ckdev; struct input_dev *idev; struct device_node *np; int err; np = pdev->dev.of_node; if (!np) return -ENODEV; ckdev = devm_kzalloc(dev, sizeof(*ckdev), GFP_KERNEL); if (!ckdev) return -ENOMEM; err = matrix_keypad_parse_of_params(dev, &ckdev->rows, &ckdev->cols); if (err) return err; ckdev->valid_keys = devm_kzalloc(dev, ckdev->cols, GFP_KERNEL); if (!ckdev->valid_keys) return -ENOMEM; ckdev->old_kb_state = devm_kzalloc(dev, ckdev->cols, GFP_KERNEL); if (!ckdev->old_kb_state) return -ENOMEM; idev = devm_input_allocate_device(dev); if (!idev) return -ENOMEM; ckdev->ec = ec; ckdev->notifier.notifier_call = cros_ec_keyb_work; ckdev->dev = dev; dev_set_drvdata(dev, ckdev); idev->name = CROS_EC_DEV_NAME; idev->phys = ec->phys_name; __set_bit(EV_REP, idev->evbit); idev->id.bustype = BUS_VIRTUAL; idev->id.version = 1; idev->id.product = 0; idev->dev.parent = dev; idev->open = cros_ec_keyb_open; idev->close = cros_ec_keyb_close; ckdev->ghost_filter = of_property_read_bool(np, "google,needs-ghost-filter"); err = matrix_keypad_build_keymap(NULL, NULL, ckdev->rows, ckdev->cols, NULL, idev); if (err) { dev_err(dev, "cannot build key matrix\n"); return err; } ckdev->row_shift = get_count_order(ckdev->cols); input_set_capability(idev, EV_MSC, MSC_SCAN); input_set_drvdata(idev, ckdev); ckdev->idev = idev; cros_ec_keyb_compute_valid_keys(ckdev); err = input_register_device(ckdev->idev); if (err) { dev_err(dev, "cannot register input device\n"); return err; } return 0; } #ifdef CONFIG_OF static const struct of_device_id cros_ec_keyb_of_match[] = { { .compatible = "google,cros-ec-keyb" }, {}, }; MODULE_DEVICE_TABLE(of, cros_ec_keyb_of_match); #endif static struct platform_driver cros_ec_keyb_driver = { .probe = cros_ec_keyb_probe, .driver = { .name = "cros-ec-keyb", .of_match_table = of_match_ptr(cros_ec_keyb_of_match), }, }; module_platform_driver(cros_ec_keyb_driver); MODULE_LICENSE("GPL"); MODULE_DESCRIPTION("ChromeOS EC keyboard driver"); MODULE_ALIAS("platform:cros-ec-keyb");