diff options
author | André Fabian Silva Delgado <emulatorman@parabola.nu> | 2015-08-05 17:04:01 -0300 |
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committer | André Fabian Silva Delgado <emulatorman@parabola.nu> | 2015-08-05 17:04:01 -0300 |
commit | 57f0f512b273f60d52568b8c6b77e17f5636edc0 (patch) | |
tree | 5e910f0e82173f4ef4f51111366a3f1299037a7b /drivers/input/keyboard/cros_ec_keyb.c |
Initial import
Diffstat (limited to 'drivers/input/keyboard/cros_ec_keyb.c')
-rw-r--r-- | drivers/input/keyboard/cros_ec_keyb.c | 375 |
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"); |