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