// SPDX-License-Identifier: GPL-2.0+
/*
 * Chromium OS Matrix Keyboard
 *
 * Copyright (c) 2012 The Chromium OS Authors.
 */

#include <common.h>
#include <cros_ec.h>
#include <dm.h>
#include <errno.h>
#include <input.h>
#include <keyboard.h>
#include <key_matrix.h>
#include <stdio_dev.h>

enum {
        KBC_MAX_KEYS            = 8,    /* Maximum keys held down at once */
        KBC_REPEAT_RATE_MS      = 30,
        KBC_REPEAT_DELAY_MS     = 240,
};

struct cros_ec_keyb_priv {
        struct input_config *input;     /* The input layer */
        struct key_matrix matrix;       /* The key matrix layer */
        int key_rows;                   /* Number of keyboard rows */
        int key_cols;                   /* Number of keyboard columns */
        int ghost_filter;               /* 1 to enable ghost filter, else 0 */
};


/**
 * Check the keyboard controller and return a list of key matrix positions
 * for which a key is pressed
 *
 * @param dev           Keyboard device
 * @param keys          List of keys that we have detected
 * @param max_count     Maximum number of keys to return
 * @param samep         Set to true if this scan repeats the last, else false
 * @return number of pressed keys, 0 for none, -EIO on error
 */
static int check_for_keys(struct udevice *dev, struct key_matrix_key *keys,
                          int max_count, bool *samep)
{
        struct cros_ec_keyb_priv *priv = dev_get_priv(dev);
        struct key_matrix_key *key;
        static struct mbkp_keyscan last_scan;
        static bool last_scan_valid;
        struct mbkp_keyscan scan;
        unsigned int row, col, bit, data;
        int num_keys;

        if (cros_ec_scan_keyboard(dev->parent, &scan)) {
                debug("%s: keyboard scan failed\n", __func__);
                return -EIO;
        }
        *samep = last_scan_valid && !memcmp(&last_scan, &scan, sizeof(scan));

        /*
         * This is a bit odd. The EC has no way to tell us that it has run
         * out of key scans. It just returns the same scan over and over
         * again. So the only way to detect that we have run out is to detect
         * that this scan is the same as the last.
         */
        last_scan_valid = true;
        memcpy(&last_scan, &scan, sizeof(last_scan));

        for (col = num_keys = bit = 0; col < priv->matrix.num_cols;
                        col++) {
                for (row = 0; row < priv->matrix.num_rows; row++) {
                        unsigned int mask = 1 << (bit & 7);

                        data = scan.data[bit / 8];
                        if ((data & mask) && num_keys < max_count) {
                                key = keys + num_keys++;
                                key->row = row;
                                key->col = col;
                                key->valid = 1;
                        }
                        bit++;
                }
        }

        return num_keys;
}

/**
 * Check the keyboard, and send any keys that are pressed.
 *
 * This is called by input_tstc() and input_getc() when they need more
 * characters
 *
 * @param input         Input configuration
 * @return 1, to indicate that we have something to look at
 */
int cros_ec_kbc_check(struct input_config *input)
{
        struct udevice *dev = input->dev;
        struct cros_ec_keyb_priv *priv = dev_get_priv(dev);
        static struct key_matrix_key last_keys[KBC_MAX_KEYS];
        static int last_num_keys;
        struct key_matrix_key keys[KBC_MAX_KEYS];
        int keycodes[KBC_MAX_KEYS];
        int num_keys, num_keycodes;
        int irq_pending, sent;
        bool same = false;

        /*
         * Loop until the EC has no more keyscan records, or we have
         * received at least one character. This means we know that tstc()
         * will always return non-zero if keys have been pressed.
         *
         * Without this loop, a key release (which generates no new ascii
         * characters) will cause us to exit this function, and just tstc()
         * may return 0 before all keys have been read from the EC.
         */
        do {
                irq_pending = cros_ec_interrupt_pending(dev->parent);
                if (irq_pending) {
                        num_keys = check_for_keys(dev, keys, KBC_MAX_KEYS,
                                                  &same);
                        if (num_keys < 0)
                                return 0;
                        last_num_keys = num_keys;
                        memcpy(last_keys, keys, sizeof(keys));
                } else {
                        /*
                         * EC doesn't want to be asked, so use keys from last
                         * time.
                         */
                        num_keys = last_num_keys;
                        memcpy(keys, last_keys, sizeof(keys));
                }

                if (num_keys < 0)
                        return -1;
                num_keycodes = key_matrix_decode(&priv->matrix, keys,
                                num_keys, keycodes, KBC_MAX_KEYS);
                sent = input_send_keycodes(input, keycodes, num_keycodes);

                /*
                 * For those ECs without an interrupt, stop scanning when we
                 * see that the scan is the same as last time.
                 */
                if ((irq_pending < 0) && same)
                        break;
        } while (irq_pending && !sent);

        return 1;
}

/**
 * Decode MBKP keyboard details from the device tree
 *
 * @param blob          Device tree blob
 * @param node          Node to decode from
 * @param config        Configuration data read from fdt
 * @return 0 if ok, -1 on error
 */
static int cros_ec_keyb_decode_fdt(struct udevice *dev,
                                   struct cros_ec_keyb_priv *config)
{
        /*
         * Get keyboard rows and columns - at present we are limited to
         * 8 columns by the protocol (one byte per row scan)
         */
        config->key_rows = dev_read_u32_default(dev, "keypad,num-rows", 0);
        config->key_cols = dev_read_u32_default(dev, "keypad,num-columns", 0);
        if (!config->key_rows || !config->key_cols ||
                        config->key_rows * config->key_cols / 8
                                > CROS_EC_KEYSCAN_COLS) {
                debug("%s: Invalid key matrix size %d x %d\n", __func__,
                      config->key_rows, config->key_cols);
                return -1;
        }
        config->ghost_filter = dev_read_bool(dev, "google,needs-ghost-filter");

        return 0;
}

static int cros_ec_kbd_probe(struct udevice *dev)
{
        struct cros_ec_keyb_priv *priv = dev_get_priv(dev);
        struct keyboard_priv *uc_priv = dev_get_uclass_priv(dev);
        struct stdio_dev *sdev = &uc_priv->sdev;
        struct input_config *input = &uc_priv->input;
        int ret;

        ret = cros_ec_keyb_decode_fdt(dev, priv);
        if (ret) {
                debug("%s: Cannot decode node (ret=%d)\n", __func__, ret);
                return -EINVAL;
        }
        input_set_delays(input, KBC_REPEAT_DELAY_MS, KBC_REPEAT_RATE_MS);
        ret = key_matrix_init(&priv->matrix, priv->key_rows, priv->key_cols,
                              priv->ghost_filter);
        if (ret) {
                debug("%s: cannot init key matrix\n", __func__);
                return ret;
        }
        ret = key_matrix_decode_fdt(dev, &priv->matrix);
        if (ret) {
                debug("%s: Could not decode key matrix from fdt\n", __func__);
                return ret;
        }
        debug("%s: Matrix keyboard %dx%d ready\n", __func__, priv->key_rows,
              priv->key_cols);

        priv->input = input;
        input->dev = dev;
        input_add_tables(input, false);
        input->read_keys = cros_ec_kbc_check;
        strcpy(sdev->name, "cros-ec-keyb");

        /* Register the device. cros_ec_init_keyboard() will be called soon */
        return input_stdio_register(sdev);
}

static const struct keyboard_ops cros_ec_kbd_ops = {
};

static const struct udevice_id cros_ec_kbd_ids[] = {
        { .compatible = "google,cros-ec-keyb" },
        { }
};

U_BOOT_DRIVER(cros_ec_kbd) = {
        .name   = "cros_ec_kbd",
        .id     = UCLASS_KEYBOARD,
        .of_match = cros_ec_kbd_ids,
        .probe = cros_ec_kbd_probe,
        .ops    = &cros_ec_kbd_ops,
        .priv_auto_alloc_size = sizeof(struct cros_ec_keyb_priv),
};