/*
 * 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/notifier.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/sysrq.h>
#include <linux/input/matrix_keypad.h>
#include <linux/mfd/cros_ec.h>
#include <linux/mfd/cros_ec_commands.h>

#include <asm/unaligned.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
 * @ec: Top level ChromeOS device to use to talk to EC
 * @idev: The input device for the matrix keys.
 * @bs_idev: The input device for non-matrix buttons and switches (or NULL).
 * @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 cros_ec_device *ec;

        struct input_dev *idev;
        struct input_dev *bs_idev;
        struct notifier_block notifier;
};


/**
 * cros_ec_bs_map - Struct mapping Linux keycodes to EC button/switch bitmap
 * #defines
 *
 * @ev_type: The type of the input event to generate (e.g., EV_KEY).
 * @code: A linux keycode
 * @bit: A #define like EC_MKBP_POWER_BUTTON or EC_MKBP_LID_OPEN
 * @inverted: If the #define and EV_SW have opposite meanings, this is true.
 *            Only applicable to switches.
 */
struct cros_ec_bs_map {
        unsigned int ev_type;
        unsigned int code;
        u8 bit;
        bool inverted;
};

/* cros_ec_keyb_bs - Map EC button/switch #defines into kernel ones */
static const struct cros_ec_bs_map cros_ec_keyb_bs[] = {
        /* Buttons */
        {
                .ev_type        = EV_KEY,
                .code           = KEY_POWER,
                .bit            = EC_MKBP_POWER_BUTTON,
        },
        {
                .ev_type        = EV_KEY,
                .code           = KEY_VOLUMEUP,
                .bit            = EC_MKBP_VOL_UP,
        },
        {
                .ev_type        = EV_KEY,
                .code           = KEY_VOLUMEDOWN,
                .bit            = EC_MKBP_VOL_DOWN,
        },

        /* Switches */
        {
                .ev_type        = EV_SW,
                .code           = SW_LID,
                .bit            = EC_MKBP_LID_OPEN,
                .inverted       = true,
        },
        {
                .ev_type        = EV_SW,
                .code           = SW_TABLET_MODE,
                .bit            = EC_MKBP_TABLET_MODE,
        },
};

/*
 * 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);
}

/**
 * cros_ec_keyb_report_bs - Report non-matrixed buttons or switches
 *
 * This takes a bitmap of buttons or switches from the EC and reports events,
 * syncing at the end.
 *
 * @ckdev: The keyboard device.
 * @ev_type: The input event type (e.g., EV_KEY).
 * @mask: A bitmap of buttons from the EC.
 */
static void cros_ec_keyb_report_bs(struct cros_ec_keyb *ckdev,
                                   unsigned int ev_type, u32 mask)

{
        struct input_dev *idev = ckdev->bs_idev;
        int i;

        for (i = 0; i < ARRAY_SIZE(cros_ec_keyb_bs); i++) {
                const struct cros_ec_bs_map *map = &cros_ec_keyb_bs[i];

                if (map->ev_type != ev_type)
                        continue;

                input_event(idev, ev_type, map->code,
                            !!(mask & BIT(map->bit)) ^ map->inverted);
        }
        input_sync(idev);
}

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);
        u32 val;
        unsigned int ev_type;

        switch (ckdev->ec->event_data.event_type) {
        case EC_MKBP_EVENT_KEY_MATRIX:
                /*
                 * 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);
                break;

        case EC_MKBP_EVENT_SYSRQ:
                val = get_unaligned_le32(&ckdev->ec->event_data.data.sysrq);
                dev_dbg(ckdev->dev, "sysrq code from EC: %#x\n", val);
                handle_sysrq(val);
                break;

        case EC_MKBP_EVENT_BUTTON:
        case EC_MKBP_EVENT_SWITCH:
                /*
                 * If EC is not the wake source, discard key state
                 * changes during suspend. Switches will be re-checked in
                 * cros_ec_keyb_resume() to be sure nothing is lost.
                 */
                if (queued_during_suspend)
                        return NOTIFY_OK;

                if (ckdev->ec->event_data.event_type == EC_MKBP_EVENT_BUTTON) {
                        val = get_unaligned_le32(
                                        &ckdev->ec->event_data.data.buttons);
                        ev_type = EV_KEY;
                } else {
                        val = get_unaligned_le32(
                                        &ckdev->ec->event_data.data.switches);
                        ev_type = EV_SW;
                }
                cros_ec_keyb_report_bs(ckdev, ev_type, val);
                break;

        default:
                return NOTIFY_DONE;
        }

        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]);
        }
}

/**
 * cros_ec_keyb_info - Wrap the EC command EC_CMD_MKBP_INFO
 *
 * This wraps the EC_CMD_MKBP_INFO, abstracting out all of the marshalling and
 * unmarshalling and different version nonsense into something simple.
 *
 * @ec_dev: The EC device
 * @info_type: Either EC_MKBP_INFO_SUPPORTED or EC_MKBP_INFO_CURRENT.
 * @event_type: Either EC_MKBP_EVENT_BUTTON or EC_MKBP_EVENT_SWITCH.  Actually
 *              in some cases this could be EC_MKBP_EVENT_KEY_MATRIX or
 *              EC_MKBP_EVENT_HOST_EVENT too but we don't use in this driver.
 * @result: Where we'll store the result; a union
 * @result_size: The size of the result.  Expected to be the size of one of
 *               the elements in the union.
 *
 * Returns 0 if no error or -error upon error.
 */
static int cros_ec_keyb_info(struct cros_ec_device *ec_dev,
                             enum ec_mkbp_info_type info_type,
                             enum ec_mkbp_event event_type,
                             union ec_response_get_next_data *result,
                             size_t result_size)
{
        struct ec_params_mkbp_info *params;
        struct cros_ec_command *msg;
        int ret;

        msg = kzalloc(sizeof(*msg) + max_t(size_t, result_size,
                                           sizeof(*params)), GFP_KERNEL);
        if (!msg)
                return -ENOMEM;

        msg->command = EC_CMD_MKBP_INFO;
        msg->version = 1;
        msg->outsize = sizeof(*params);
        msg->insize = result_size;
        params = (struct ec_params_mkbp_info *)msg->data;
        params->info_type = info_type;
        params->event_type = event_type;

        ret = cros_ec_cmd_xfer(ec_dev, msg);
        if (ret < 0) {
                dev_warn(ec_dev->dev, "Transfer error %d/%d: %d\n",
                         (int)info_type, (int)event_type, ret);
        } else if (msg->result == EC_RES_INVALID_VERSION) {
                /* With older ECs we just return 0 for everything */
                memset(result, 0, result_size);
                ret = 0;
        } else if (msg->result != EC_RES_SUCCESS) {
                dev_warn(ec_dev->dev, "Error getting info %d/%d: %d\n",
                         (int)info_type, (int)event_type, msg->result);
                ret = -EPROTO;
        } else if (ret != result_size) {
                dev_warn(ec_dev->dev, "Wrong size %d/%d: %d != %zu\n",
                         (int)info_type, (int)event_type,
                         ret, result_size);
                ret = -EPROTO;
        } else {
                memcpy(result, msg->data, result_size);
                ret = 0;
        }

        kfree(msg);

        return ret;
}

/**
 * cros_ec_keyb_query_switches - Query the state of switches and report
 *
 * This will ask the EC about the current state of switches and report to the
 * kernel.  Note that we don't query for buttons because they are more
 * transitory and we'll get an update on the next release / press.
 *
 * @ckdev: The keyboard device
 *
 * Returns 0 if no error or -error upon error.
 */
static int cros_ec_keyb_query_switches(struct cros_ec_keyb *ckdev)
{
        struct cros_ec_device *ec_dev = ckdev->ec;
        union ec_response_get_next_data event_data = {};
        int ret;

        ret = cros_ec_keyb_info(ec_dev, EC_MKBP_INFO_CURRENT,
                                EC_MKBP_EVENT_SWITCH, &event_data,
                                sizeof(event_data.switches));
        if (ret)
                return ret;

        cros_ec_keyb_report_bs(ckdev, EV_SW,
                               get_unaligned_le32(&event_data.switches));

        return 0;
}

/**
 * cros_ec_keyb_resume - Resume the keyboard
 *
 * We use the resume notification as a chance to query the EC for switches.
 *
 * @dev: The keyboard device
 *
 * Returns 0 if no error or -error upon error.
 */
static __maybe_unused int cros_ec_keyb_resume(struct device *dev)
{
        struct cros_ec_keyb *ckdev = dev_get_drvdata(dev);

        if (ckdev->bs_idev)
                return cros_ec_keyb_query_switches(ckdev);

        return 0;
}

/**
 * cros_ec_keyb_register_bs - Register non-matrix buttons/switches
 *
 * Handles all the bits of the keyboard driver related to non-matrix buttons
 * and switches, including asking the EC about which are present and telling
 * the kernel to expect them.
 *
 * If this device has no support for buttons and switches we'll return no error
 * but the ckdev->bs_idev will remain NULL when this function exits.
 *
 * @ckdev: The keyboard device
 *
 * Returns 0 if no error or -error upon error.
 */
static int cros_ec_keyb_register_bs(struct cros_ec_keyb *ckdev)
{
        struct cros_ec_device *ec_dev = ckdev->ec;
        struct device *dev = ckdev->dev;
        struct input_dev *idev;
        union ec_response_get_next_data event_data = {};
        const char *phys;
        u32 buttons;
        u32 switches;
        int ret;
        int i;

        ret = cros_ec_keyb_info(ec_dev, EC_MKBP_INFO_SUPPORTED,
                                EC_MKBP_EVENT_BUTTON, &event_data,
                                sizeof(event_data.buttons));
        if (ret)
                return ret;
        buttons = get_unaligned_le32(&event_data.buttons);

        ret = cros_ec_keyb_info(ec_dev, EC_MKBP_INFO_SUPPORTED,
                                EC_MKBP_EVENT_SWITCH, &event_data,
                                sizeof(event_data.switches));
        if (ret)
                return ret;
        switches = get_unaligned_le32(&event_data.switches);

        if (!buttons && !switches)
                return 0;

        /*
         * We call the non-matrix buttons/switches 'input1', if present.
         * Allocate phys before input dev, to ensure correct tear-down
         * ordering.
         */
        phys = devm_kasprintf(dev, GFP_KERNEL, "%s/input1", ec_dev->phys_name);
        if (!phys)
                return -ENOMEM;

        idev = devm_input_allocate_device(dev);
        if (!idev)
                return -ENOMEM;

        idev->name = "cros_ec_buttons";
        idev->phys = phys;
        __set_bit(EV_REP, idev->evbit);

        idev->id.bustype = BUS_VIRTUAL;
        idev->id.version = 1;
        idev->id.product = 0;
        idev->dev.parent = dev;

        input_set_drvdata(idev, ckdev);
        ckdev->bs_idev = idev;

        for (i = 0; i < ARRAY_SIZE(cros_ec_keyb_bs); i++) {
                const struct cros_ec_bs_map *map = &cros_ec_keyb_bs[i];

                if (buttons & BIT(map->bit))
                        input_set_capability(idev, map->ev_type, map->code);
        }

        ret = cros_ec_keyb_query_switches(ckdev);
        if (ret) {
                dev_err(dev, "cannot query switches\n");
                return ret;
        }

        ret = input_register_device(ckdev->bs_idev);
        if (ret) {
                dev_err(dev, "cannot register input device\n");
                return ret;
        }

        return 0;
}

/**
 * cros_ec_keyb_register_bs - Register matrix keys
 *
 * Handles all the bits of the keyboard driver related to matrix keys.
 *
 * @ckdev: The keyboard device
 *
 * Returns 0 if no error or -error upon error.
 */
static int cros_ec_keyb_register_matrix(struct cros_ec_keyb *ckdev)
{
        struct cros_ec_device *ec_dev = ckdev->ec;
        struct device *dev = ckdev->dev;
        struct input_dev *idev;
        const char *phys;
        int err;

        err = matrix_keypad_parse_properties(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;

        /*
         * We call the keyboard matrix 'input0'. Allocate phys before input
         * dev, to ensure correct tear-down ordering.
         */
        phys = devm_kasprintf(dev, GFP_KERNEL, "%s/input0", ec_dev->phys_name);
        if (!phys)
                return -ENOMEM;

        idev = devm_input_allocate_device(dev);
        if (!idev)
                return -ENOMEM;

        idev->name = CROS_EC_DEV_NAME;
        idev->phys = phys;
        __set_bit(EV_REP, idev->evbit);

        idev->id.bustype = BUS_VIRTUAL;
        idev->id.version = 1;
        idev->id.product = 0;
        idev->dev.parent = dev;

        ckdev->ghost_filter = of_property_read_bool(dev->of_node,
                                        "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;
}

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;
        int err;

        if (!dev->of_node)
                return -ENODEV;

        ckdev = devm_kzalloc(dev, sizeof(*ckdev), GFP_KERNEL);
        if (!ckdev)
                return -ENOMEM;

        ckdev->ec = ec;
        ckdev->dev = dev;
        dev_set_drvdata(dev, ckdev);

        err = cros_ec_keyb_register_matrix(ckdev);
        if (err) {
                dev_err(dev, "cannot register matrix inputs: %d\n", err);
                return err;
        }

        err = cros_ec_keyb_register_bs(ckdev);
        if (err) {
                dev_err(dev, "cannot register non-matrix inputs: %d\n", err);
                return err;
        }

        ckdev->notifier.notifier_call = cros_ec_keyb_work;
        err = blocking_notifier_chain_register(&ckdev->ec->event_notifier,
                                               &ckdev->notifier);
        if (err) {
                dev_err(dev, "cannot register notifier: %d\n", err);
                return err;
        }

        return 0;
}

static int cros_ec_keyb_remove(struct platform_device *pdev)
{
        struct cros_ec_keyb *ckdev = dev_get_drvdata(&pdev->dev);

        blocking_notifier_chain_unregister(&ckdev->ec->event_notifier,
                                           &ckdev->notifier);

        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 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,
        .remove = cros_ec_keyb_remove,
        .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");