Initial import

1 files changed, 375 insertions, 0 deletions

diff --git a/drivers/input/keyboard/cros_ec_keyb.c b/drivers/input/keyboard/cros_ec_keyb.c
new file mode 100644
index 000000000..b50c5b8b8
--- /dev/null
+++ b/drivers/input/keyboard/cros_ec_keyb.c
@@ -0,0 +1,375 @@
+/*
+ * 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 <linux/module.h>
+#include <linux/bitops.h>
+#include <linux/i2c.h>
+#include <linux/input.h>
+#include <linux/interrupt.h>
+#include <linux/kernel.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/input/matrix_keypad.h>
+#include <linux/mfd/cros_ec.h>
+#include <linux/mfd/cros_ec_commands.h>
+
+/*
+ * @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
+ */
+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;
+};
+
+
+/*
+ * 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_get_state(struct cros_ec_keyb *ckdev, uint8_t *kb_state)
+{
+	int ret;
+	struct cros_ec_command msg = {
+		.command = EC_CMD_MKBP_STATE,
+		.insize = ckdev->cols,
+	};
+
+	ret = cros_ec_cmd_xfer(ckdev->ec, &msg);
+	if (ret < 0)
+		return ret;
+
+	memcpy(kb_state, msg.indata, ckdev->cols);
+
+	return 0;
+}
+
+static irqreturn_t cros_ec_keyb_irq(int irq, void *data)
+{
+	struct cros_ec_keyb *ckdev = data;
+	struct cros_ec_device *ec = ckdev->ec;
+	int ret;
+	uint8_t kb_state[ckdev->cols];
+
+	if (device_may_wakeup(ec->dev))
+		pm_wakeup_event(ec->dev, 0);
+
+	ret = cros_ec_keyb_get_state(ckdev, kb_state);
+	if (ret >= 0)
+		cros_ec_keyb_process(ckdev, kb_state, ret);
+	else
+		dev_err(ec->dev, "failed to get keyboard state: %d\n", ret);
+
+	return IRQ_HANDLED;
+}
+
+static int cros_ec_keyb_open(struct input_dev *dev)
+{
+	struct cros_ec_keyb *ckdev = input_get_drvdata(dev);
+	struct cros_ec_device *ec = ckdev->ec;
+
+	return request_threaded_irq(ec->irq, NULL, cros_ec_keyb_irq,
+					IRQF_TRIGGER_LOW | IRQF_ONESHOT,
+					"cros_ec_keyb", ckdev);
+}
+
+static void cros_ec_keyb_close(struct input_dev *dev)
+{
+	struct cros_ec_keyb *ckdev = input_get_drvdata(dev);
+	struct cros_ec_device *ec = ckdev->ec;
+
+	free_irq(ec->irq, ckdev);
+}
+
+/*
+ * 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 = ec->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(&pdev->dev, sizeof(*ckdev), GFP_KERNEL);
+	if (!ckdev)
+		return -ENOMEM;
+	err = matrix_keypad_parse_of_params(&pdev->dev, &ckdev->rows,
+					    &ckdev->cols);
+	if (err)
+		return err;
+
+	ckdev->valid_keys = devm_kzalloc(&pdev->dev, ckdev->cols, GFP_KERNEL);
+	if (!ckdev->valid_keys)
+		return -ENOMEM;
+
+	ckdev->old_kb_state = devm_kzalloc(&pdev->dev, ckdev->cols, GFP_KERNEL);
+	if (!ckdev->old_kb_state)
+		return -ENOMEM;
+
+	idev = devm_input_allocate_device(&pdev->dev);
+	if (!idev)
+		return -ENOMEM;
+
+	if (!ec->irq) {
+		dev_err(dev, "no EC IRQ specified\n");
+		return -EINVAL;
+	}
+
+	ckdev->ec = ec;
+	ckdev->dev = dev;
+	dev_set_drvdata(&pdev->dev, ckdev);
+
+	idev->name = ec->ec_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 = &pdev->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_PM_SLEEP
+/* Clear any keys in the buffer */
+static void cros_ec_keyb_clear_keyboard(struct cros_ec_keyb *ckdev)
+{
+	uint8_t old_state[ckdev->cols];
+	uint8_t new_state[ckdev->cols];
+	unsigned long duration;
+	int i, ret;
+
+	/*
+	 * Keep reading until we see that the scan state does not change.
+	 * That indicates that we are done.
+	 *
+	 * Assume that the EC keyscan buffer is at most 32 deep.
+	 */
+	duration = jiffies;
+	ret = cros_ec_keyb_get_state(ckdev, new_state);
+	for (i = 1; !ret && i < 32; i++) {
+		memcpy(old_state, new_state, sizeof(old_state));
+		ret = cros_ec_keyb_get_state(ckdev, new_state);
+		if (0 == memcmp(old_state, new_state, sizeof(old_state)))
+			break;
+	}
+	duration = jiffies - duration;
+	dev_info(ckdev->dev, "Discarded %d keyscan(s) in %dus\n", i,
+		jiffies_to_usecs(duration));
+}
+
+static int cros_ec_keyb_resume(struct device *dev)
+{
+	struct cros_ec_keyb *ckdev = dev_get_drvdata(dev);
+
+	/*
+	 * When the EC is not a wake source, then it could not have caused the
+	 * resume, so we clear the EC's key scan buffer. If the EC was a
+	 * wake source (e.g. the lid is open and the user might press a key to
+	 * wake) then the key scan buffer should be preserved.
+	 */
+	if (!ckdev->ec->was_wake_device)
+		cros_ec_keyb_clear_keyboard(ckdev);
+
+	return 0;
+}
+
+#endif
+
+static SIMPLE_DEV_PM_OPS(cros_ec_keyb_pm_ops, NULL, cros_ec_keyb_resume);
+
+#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),
+		.pm	= &cros_ec_keyb_pm_ops,
+	},
+};
+
+module_platform_driver(cros_ec_keyb_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("ChromeOS EC keyboard driver");
+MODULE_ALIAS("platform:cros-ec-keyb");