/*
 * Helpers for matrix keyboard bindings
 *
 * Copyright (C) 2012 Google, Inc
 *
 * Author:
 *      Olof Johansson <olof@lixom.net>
 *
 * 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.
 */

#include <linux/device.h>
#include <linux/export.h>
#include <linux/gfp.h>
#include <linux/input.h>
#include <linux/input/matrix_keypad.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/property.h>
#include <linux/slab.h>
#include <linux/types.h>

static bool matrix_keypad_map_key(struct input_dev *input_dev,
                                  unsigned int rows, unsigned int cols,
                                  unsigned int row_shift, unsigned int key)
{
        unsigned short *keymap = input_dev->keycode;
        unsigned int row = KEY_ROW(key);
        unsigned int col = KEY_COL(key);
        unsigned short code = KEY_VAL(key);

        if (row >= rows || col >= cols) {
                dev_err(input_dev->dev.parent,
                        "%s: invalid keymap entry 0x%x (row: %d, col: %d, rows: %d, cols: %d)\n",
                        __func__, key, row, col, rows, cols);
                return false;
        }

        keymap[MATRIX_SCAN_CODE(row, col, row_shift)] = code;
        __set_bit(code, input_dev->keybit);

        return true;
}

/**
 * matrix_keypad_parse_properties() - Read properties of matrix keypad
 *
 * @dev: Device containing properties
 * @rows: Returns number of matrix rows
 * @cols: Returns number of matrix columns
 * @return 0 if OK, <0 on error
 */
int matrix_keypad_parse_properties(struct device *dev,
                                   unsigned int *rows, unsigned int *cols)
{
        *rows = *cols = 0;

        device_property_read_u32(dev, "keypad,num-rows", rows);
        device_property_read_u32(dev, "keypad,num-columns", cols);

        if (!*rows || !*cols) {
                dev_err(dev, "number of keypad rows/columns not specified\n");
                return -EINVAL;
        }

        return 0;
}
EXPORT_SYMBOL_GPL(matrix_keypad_parse_properties);

static int matrix_keypad_parse_keymap(const char *propname,
                                      unsigned int rows, unsigned int cols,
                                      struct input_dev *input_dev)
{
        struct device *dev = input_dev->dev.parent;
        unsigned int row_shift = get_count_order(cols);
        unsigned int max_keys = rows << row_shift;
        u32 *keys;
        int i;
        int size;
        int retval;

        if (!propname)
                propname = "linux,keymap";

        size = device_property_read_u32_array(dev, propname, NULL, 0);
        if (size <= 0) {
                dev_err(dev, "missing or malformed property %s: %d\n",
                        propname, size);
                return size < 0 ? size : -EINVAL;
        }

        if (size > max_keys) {
                dev_err(dev, "%s size overflow (%d vs max %u)\n",
                        propname, size, max_keys);
                return -EINVAL;
        }

        keys = kmalloc_array(size, sizeof(u32), GFP_KERNEL);
        if (!keys)
                return -ENOMEM;

        retval = device_property_read_u32_array(dev, propname, keys, size);
        if (retval) {
                dev_err(dev, "failed to read %s property: %d\n",
                        propname, retval);
                goto out;
        }

        for (i = 0; i < size; i++) {
                if (!matrix_keypad_map_key(input_dev, rows, cols,
                                           row_shift, keys[i])) {
                        retval = -EINVAL;
                        goto out;
                }
        }

        retval = 0;

out:
        kfree(keys);
        return retval;
}

/**
 * matrix_keypad_build_keymap - convert platform keymap into matrix keymap
 * @keymap_data: keymap supplied by the platform code
 * @keymap_name: name of device tree property containing keymap (if device
 *      tree support is enabled).
 * @rows: number of rows in target keymap array
 * @cols: number of cols in target keymap array
 * @keymap: expanded version of keymap that is suitable for use by
 * matrix keyboard driver
 * @input_dev: input devices for which we are setting up the keymap
 *
 * This function converts platform keymap (encoded with KEY() macro) into
 * an array of keycodes that is suitable for using in a standard matrix
 * keyboard driver that uses row and col as indices.
 *
 * If @keymap_data is not supplied and device tree support is enabled
 * it will attempt load the keymap from property specified by @keymap_name
 * argument (or "linux,keymap" if @keymap_name is %NULL).
 *
 * If @keymap is %NULL the function will automatically allocate managed
 * block of memory to store the keymap. This memory will be associated with
 * the parent device and automatically freed when device unbinds from the
 * driver.
 *
 * Callers are expected to set up input_dev->dev.parent before calling this
 * function.
 */
int matrix_keypad_build_keymap(const struct matrix_keymap_data *keymap_data,
                               const char *keymap_name,
                               unsigned int rows, unsigned int cols,
                               unsigned short *keymap,
                               struct input_dev *input_dev)
{
        unsigned int row_shift = get_count_order(cols);
        size_t max_keys = rows << row_shift;
        int i;
        int error;

        if (WARN_ON(!input_dev->dev.parent))
                return -EINVAL;

        if (!keymap) {
                keymap = devm_kzalloc(input_dev->dev.parent,
                                      max_keys * sizeof(*keymap),
                                      GFP_KERNEL);
                if (!keymap) {
                        dev_err(input_dev->dev.parent,
                                "Unable to allocate memory for keymap");
                        return -ENOMEM;
                }
        }

        input_dev->keycode = keymap;
        input_dev->keycodesize = sizeof(*keymap);
        input_dev->keycodemax = max_keys;

        __set_bit(EV_KEY, input_dev->evbit);

        if (keymap_data) {
                for (i = 0; i < keymap_data->keymap_size; i++) {
                        unsigned int key = keymap_data->keymap[i];

                        if (!matrix_keypad_map_key(input_dev, rows, cols,
                                                   row_shift, key))
                                return -EINVAL;
                }
        } else {
                error = matrix_keypad_parse_keymap(keymap_name, rows, cols,
                                                   input_dev);
                if (error)
                        return error;
        }

        __clear_bit(KEY_RESERVED, input_dev->keybit);

        return 0;
}
EXPORT_SYMBOL(matrix_keypad_build_keymap);

MODULE_LICENSE("GPL");