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authorSimon Glass <sjg@chromium.org>2013-02-26 02:08:41 +0400
committerSamuel Ortiz <sameo@linux.intel.com>2013-04-05 13:20:13 +0400
commit6af6dc2d2aa654e928ed0a64c28724d1cd2c36c1 (patch)
tree323ea72f7fe7d9fb897865ee47184d84ca52c318 /drivers
parent43840415339f1600f281211cfb5400fab696536e (diff)
downloadlinux-6af6dc2d2aa654e928ed0a64c28724d1cd2c36c1.tar.xz
input: Add ChromeOS EC keyboard driver
Use the key-matrix layer to interpret key scan information from the EC and inject input based on the FDT-supplied key map. This driver registers itself with the ChromeOS EC driver to perform communications. The matrix-keypad FDT binding is used with a small addition to control ghosting. Signed-off-by: Simon Glass <sjg@chromium.org> Signed-off-by: Luigi Semenzato <semenzato@chromium.org> Signed-off-by: Vincent Palatin <vpalatin@chromium.org> Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com> Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/input/keyboard/Kconfig12
-rw-r--r--drivers/input/keyboard/Makefile1
-rw-r--r--drivers/input/keyboard/cros_ec_keyb.c334
3 files changed, 347 insertions, 0 deletions
diff --git a/drivers/input/keyboard/Kconfig b/drivers/input/keyboard/Kconfig
index ac0500667000..6a195d5e90ff 100644
--- a/drivers/input/keyboard/Kconfig
+++ b/drivers/input/keyboard/Kconfig
@@ -628,4 +628,16 @@ config KEYBOARD_W90P910
To compile this driver as a module, choose M here: the
module will be called w90p910_keypad.
+config KEYBOARD_CROS_EC
+ tristate "ChromeOS EC keyboard"
+ select INPUT_MATRIXKMAP
+ depends on MFD_CROS_EC
+ help
+ Say Y here to enable the matrix keyboard used by ChromeOS devices
+ and implemented on the ChromeOS EC. You must enable one bus option
+ (MFD_CROS_EC_I2C or MFD_CROS_EC_SPI) to use this.
+
+ To compile this driver as a module, choose M here: the
+ module will be called cros_ec_keyb.
+
endif
diff --git a/drivers/input/keyboard/Makefile b/drivers/input/keyboard/Makefile
index 49b16453d00e..0c43e8cf8d0e 100644
--- a/drivers/input/keyboard/Makefile
+++ b/drivers/input/keyboard/Makefile
@@ -11,6 +11,7 @@ obj-$(CONFIG_KEYBOARD_AMIGA) += amikbd.o
obj-$(CONFIG_KEYBOARD_ATARI) += atakbd.o
obj-$(CONFIG_KEYBOARD_ATKBD) += atkbd.o
obj-$(CONFIG_KEYBOARD_BFIN) += bf54x-keys.o
+obj-$(CONFIG_KEYBOARD_CROS_EC) += cros_ec_keyb.o
obj-$(CONFIG_KEYBOARD_DAVINCI) += davinci_keyscan.o
obj-$(CONFIG_KEYBOARD_EP93XX) += ep93xx_keypad.o
obj-$(CONFIG_KEYBOARD_GOLDFISH_EVENTS) += goldfish_events.o
diff --git a/drivers/input/keyboard/cros_ec_keyb.c b/drivers/input/keyboard/cros_ec_keyb.c
new file mode 100644
index 000000000000..49557f27bfa6
--- /dev/null
+++ b/drivers/input/keyboard/cros_ec_keyb.c
@@ -0,0 +1,334 @@
+/*
+ * 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/i2c.h>
+#include <linux/input.h>
+#include <linux/kernel.h>
+#include <linux/notifier.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
+ * @dev: Device pointer
+ * @idev: Input device
+ * @ec: Top level ChromeOS device to use to talk to EC
+ * @event_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;
+
+ struct device *dev;
+ struct input_dev *idev;
+ struct cros_ec_device *ec;
+ struct notifier_block notifier;
+};
+
+
+static bool cros_ec_keyb_row_has_ghosting(struct cros_ec_keyb *ckdev,
+ uint8_t *buf, int row)
+{
+ int pressed_in_row = 0;
+ int row_has_teeth = 0;
+ int col, mask;
+
+ mask = 1 << row;
+ for (col = 0; col < ckdev->cols; col++) {
+ if (buf[col] & mask) {
+ pressed_in_row++;
+ row_has_teeth |= buf[col] & ~mask;
+ if (pressed_in_row > 1 && row_has_teeth) {
+ /* ghosting */
+ dev_dbg(ckdev->dev,
+ "ghost found at: r%d c%d, pressed %d, teeth 0x%x\n",
+ row, col, pressed_in_row,
+ row_has_teeth);
+ return true;
+ }
+ }
+ }
+
+ return false;
+}
+
+/*
+ * 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 row;
+
+ /*
+ * 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).
+ *
+ * We can detect ghosting in a single pass (*) over the keyboard state
+ * by maintaining two arrays. pressed_in_row counts how many pressed
+ * keys we have found in a row. row_has_teeth is true if any of the
+ * pressed keys for this row has other pressed keys in its column. If
+ * at any point of the scan we find that a row has multiple pressed
+ * keys, and at least one of them is at the intersection with a column
+ * with multiple pressed keys, we're sure there is ghosting.
+ * Conversely, if there is ghosting, we will detect such situation for
+ * at least one key during the pass.
+ *
+ * (*) This looks linear in the number of keys, but it's not. We can
+ * cheat because the number of rows is small.
+ */
+ for (row = 0; row < ckdev->rows; row++)
+ if (cros_ec_keyb_row_has_ghosting(ckdev, buf, row))
+ 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 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;
+ int code;
+
+ code = keycodes[pos];
+ new_state = kb_state[col] & (1 << row);
+ if (!!new_state != test_bit(code, idev->key)) {
+ dev_dbg(ckdev->dev,
+ "changed: [r%d c%d]: byte %02x\n",
+ row, col, new_state);
+
+ input_report_key(idev, code, new_state);
+ }
+ }
+ }
+ 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_get_state(struct cros_ec_keyb *ckdev, uint8_t *kb_state)
+{
+ return ckdev->ec->command_recv(ckdev->ec, EC_CMD_MKBP_STATE,
+ kb_state, ckdev->cols);
+}
+
+static int cros_ec_keyb_work(struct notifier_block *nb,
+ unsigned long state, void *_notify)
+{
+ int ret;
+ struct cros_ec_keyb *ckdev = container_of(nb, struct cros_ec_keyb,
+ notifier);
+ uint8_t kb_state[ckdev->cols];
+
+ ret = cros_ec_keyb_get_state(ckdev, kb_state);
+ if (ret >= 0)
+ cros_ec_keyb_process(ckdev, kb_state, ret);
+
+ return NOTIFY_DONE;
+}
+
+/* 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_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;
+
+ idev = devm_input_allocate_device(&pdev->dev);
+ if (!idev)
+ return -ENOMEM;
+
+ ckdev->ec = ec;
+ ckdev->notifier.notifier_call = cros_ec_keyb_work;
+ 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;
+ err = input_register_device(ckdev->idev);
+ if (err) {
+ dev_err(dev, "cannot register input device\n");
+ return err;
+ }
+
+ return 0;
+}
+
+#ifdef CONFIG_PM_SLEEP
+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);
+
+static struct platform_driver cros_ec_keyb_driver = {
+ .probe = cros_ec_keyb_probe,
+ .driver = {
+ .name = "cros-ec-keyb",
+ .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");