/*
 * twl4030_keypad.c - driver for 8x8 keypad controller in twl4030 chips
 *
 * Copyright (C) 2007 Texas Instruments, Inc.
 * Copyright (C) 2008 Nokia Corporation
 *
 * Code re-written for 2430SDP by:
 * Syed Mohammed Khasim <x0khasim@ti.com>
 *
 * Initial Code:
 * Manjunatha G K <manjugk@ti.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * 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.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/input.h>
#include <linux/platform_device.h>
#include <linux/i2c/twl.h>
#include <linux/slab.h>

/*
 * The TWL4030 family chips include a keypad controller that supports
 * up to an 8x8 switch matrix.  The controller can issue system wakeup
 * events, since it uses only the always-on 32KiHz oscillator, and has
 * an internal state machine that decodes pressed keys, including
 * multi-key combinations.
 *
 * This driver lets boards define what keycodes they wish to report for
 * which scancodes, as part of the "struct twl4030_keypad_data" used in
 * the probe() routine.
 *
 * See the TPS65950 documentation; that's the general availability
 * version of the TWL5030 second generation part.
 */
#define TWL4030_MAX_ROWS        8       /* TWL4030 hard limit */
#define TWL4030_MAX_COLS        8
/*
 * Note that we add space for an extra column so that we can handle
 * row lines connected to the gnd (see twl4030_col_xlate()).
 */
#define TWL4030_ROW_SHIFT       4
#define TWL4030_KEYMAP_SIZE     (TWL4030_MAX_ROWS << TWL4030_ROW_SHIFT)

struct twl4030_keypad {
        unsigned short  keymap[TWL4030_KEYMAP_SIZE];
        u16             kp_state[TWL4030_MAX_ROWS];
        unsigned        n_rows;
        unsigned        n_cols;
        unsigned        irq;

        struct device *dbg_dev;
        struct input_dev *input;
};

/*----------------------------------------------------------------------*/

/* arbitrary prescaler value 0..7 */
#define PTV_PRESCALER                   4

/* Register Offsets */
#define KEYP_CTRL                       0x00
#define KEYP_DEB                        0x01
#define KEYP_LONG_KEY                   0x02
#define KEYP_LK_PTV                     0x03
#define KEYP_TIMEOUT_L                  0x04
#define KEYP_TIMEOUT_H                  0x05
#define KEYP_KBC                        0x06
#define KEYP_KBR                        0x07
#define KEYP_SMS                        0x08
#define KEYP_FULL_CODE_7_0              0x09    /* row 0 column status */
#define KEYP_FULL_CODE_15_8             0x0a    /* ... row 1 ... */
#define KEYP_FULL_CODE_23_16            0x0b
#define KEYP_FULL_CODE_31_24            0x0c
#define KEYP_FULL_CODE_39_32            0x0d
#define KEYP_FULL_CODE_47_40            0x0e
#define KEYP_FULL_CODE_55_48            0x0f
#define KEYP_FULL_CODE_63_56            0x10
#define KEYP_ISR1                       0x11
#define KEYP_IMR1                       0x12
#define KEYP_ISR2                       0x13
#define KEYP_IMR2                       0x14
#define KEYP_SIR                        0x15
#define KEYP_EDR                        0x16    /* edge triggers */
#define KEYP_SIH_CTRL                   0x17

/* KEYP_CTRL_REG Fields */
#define KEYP_CTRL_SOFT_NRST             BIT(0)
#define KEYP_CTRL_SOFTMODEN             BIT(1)
#define KEYP_CTRL_LK_EN                 BIT(2)
#define KEYP_CTRL_TOE_EN                BIT(3)
#define KEYP_CTRL_TOLE_EN               BIT(4)
#define KEYP_CTRL_RP_EN                 BIT(5)
#define KEYP_CTRL_KBD_ON                BIT(6)

/* KEYP_DEB, KEYP_LONG_KEY, KEYP_TIMEOUT_x*/
#define KEYP_PERIOD_US(t, prescale)     ((t) / (31 << (prescale + 1)) - 1)

/* KEYP_LK_PTV_REG Fields */
#define KEYP_LK_PTV_PTV_SHIFT           5

/* KEYP_{IMR,ISR,SIR} Fields */
#define KEYP_IMR1_MIS                   BIT(3)
#define KEYP_IMR1_TO                    BIT(2)
#define KEYP_IMR1_LK                    BIT(1)
#define KEYP_IMR1_KP                    BIT(0)

/* KEYP_EDR Fields */
#define KEYP_EDR_KP_FALLING             0x01
#define KEYP_EDR_KP_RISING              0x02
#define KEYP_EDR_KP_BOTH                0x03
#define KEYP_EDR_LK_FALLING             0x04
#define KEYP_EDR_LK_RISING              0x08
#define KEYP_EDR_TO_FALLING             0x10
#define KEYP_EDR_TO_RISING              0x20
#define KEYP_EDR_MIS_FALLING            0x40
#define KEYP_EDR_MIS_RISING             0x80


/*----------------------------------------------------------------------*/

static int twl4030_kpread(struct twl4030_keypad *kp,
                u8 *data, u32 reg, u8 num_bytes)
{
        int ret = twl_i2c_read(TWL4030_MODULE_KEYPAD, data, reg, num_bytes);

        if (ret < 0)
                dev_warn(kp->dbg_dev,
                        "Couldn't read TWL4030: %X - ret %d[%x]\n",
                         reg, ret, ret);

        return ret;
}

static int twl4030_kpwrite_u8(struct twl4030_keypad *kp, u8 data, u32 reg)
{
        int ret = twl_i2c_write_u8(TWL4030_MODULE_KEYPAD, data, reg);

        if (ret < 0)
                dev_warn(kp->dbg_dev,
                        "Could not write TWL4030: %X - ret %d[%x]\n",
                         reg, ret, ret);

        return ret;
}

static inline u16 twl4030_col_xlate(struct twl4030_keypad *kp, u8 col)
{
        /* If all bits in a row are active for all coloumns then
         * we have that row line connected to gnd. Mark this
         * key on as if it was on matrix position n_cols (ie
         * one higher than the size of the matrix).
         */
        if (col == 0xFF)
                return 1 << kp->n_cols;
        else
                return col & ((1 << kp->n_cols) - 1);
}

static int twl4030_read_kp_matrix_state(struct twl4030_keypad *kp, u16 *state)
{
        u8 new_state[TWL4030_MAX_ROWS];
        int row;
        int ret = twl4030_kpread(kp, new_state,
                                 KEYP_FULL_CODE_7_0, kp->n_rows);
        if (ret >= 0)
                for (row = 0; row < kp->n_rows; row++)
                        state[row] = twl4030_col_xlate(kp, new_state[row]);

        return ret;
}

static bool twl4030_is_in_ghost_state(struct twl4030_keypad *kp, u16 *key_state)
{
        int i;
        u16 check = 0;

        for (i = 0; i < kp->n_rows; i++) {
                u16 col = key_state[i];

                if ((col & check) && hweight16(col) > 1)
                        return true;

                check |= col;
        }

        return false;
}

static void twl4030_kp_scan(struct twl4030_keypad *kp, bool release_all)
{
        struct input_dev *input = kp->input;
        u16 new_state[TWL4030_MAX_ROWS];
        int col, row;

        if (release_all)
                memset(new_state, 0, sizeof(new_state));
        else {
                /* check for any changes */
                int ret = twl4030_read_kp_matrix_state(kp, new_state);

                if (ret < 0)    /* panic ... */
                        return;

                if (twl4030_is_in_ghost_state(kp, new_state))
                        return;
        }

        /* check for changes and print those */
        for (row = 0; row < kp->n_rows; row++) {
                int changed = new_state[row] ^ kp->kp_state[row];

                if (!changed)
                        continue;

                /* Extra column handles "all gnd" rows */
                for (col = 0; col < kp->n_cols + 1; col++) {
                        int code;

                        if (!(changed & (1 << col)))
                                continue;

                        dev_dbg(kp->dbg_dev, "key [%d:%d] %s\n", row, col,
                                (new_state[row] & (1 << col)) ?
                                "press" : "release");

                        code = MATRIX_SCAN_CODE(row, col, TWL4030_ROW_SHIFT);
                        input_event(input, EV_MSC, MSC_SCAN, code);
                        input_report_key(input, kp->keymap[code],
                                         new_state[row] & (1 << col));
                }
                kp->kp_state[row] = new_state[row];
        }
        input_sync(input);
}

/*
 * Keypad interrupt handler
 */
static irqreturn_t do_kp_irq(int irq, void *_kp)
{
        struct twl4030_keypad *kp = _kp;
        u8 reg;
        int ret;

        /* Read & Clear TWL4030 pending interrupt */
        ret = twl4030_kpread(kp, &reg, KEYP_ISR1, 1);

        /* Release all keys if I2C has gone bad or
         * the KEYP has gone to idle state */
        if (ret >= 0 && (reg & KEYP_IMR1_KP))
                twl4030_kp_scan(kp, false);
        else
                twl4030_kp_scan(kp, true);

        return IRQ_HANDLED;
}

static int twl4030_kp_program(struct twl4030_keypad *kp)
{
        u8 reg;
        int i;

        /* Enable controller, with hardware decoding but not autorepeat */
        reg = KEYP_CTRL_SOFT_NRST | KEYP_CTRL_SOFTMODEN
                | KEYP_CTRL_TOE_EN | KEYP_CTRL_KBD_ON;
        if (twl4030_kpwrite_u8(kp, reg, KEYP_CTRL) < 0)
                return -EIO;

        /* NOTE:  we could use sih_setup() here to package keypad
         * event sources as four different IRQs ... but we don't.
         */

        /* Enable TO rising and KP rising and falling edge detection */
        reg = KEYP_EDR_KP_BOTH | KEYP_EDR_TO_RISING;
        if (twl4030_kpwrite_u8(kp, reg, KEYP_EDR) < 0)
                return -EIO;

        /* Set PTV prescaler Field */
        reg = (PTV_PRESCALER << KEYP_LK_PTV_PTV_SHIFT);
        if (twl4030_kpwrite_u8(kp, reg, KEYP_LK_PTV) < 0)
                return -EIO;

        /* Set key debounce time to 20 ms */
        i = KEYP_PERIOD_US(20000, PTV_PRESCALER);
        if (twl4030_kpwrite_u8(kp, i, KEYP_DEB) < 0)
                return -EIO;

        /* Set timeout period to 200 ms */
        i = KEYP_PERIOD_US(200000, PTV_PRESCALER);
        if (twl4030_kpwrite_u8(kp, (i & 0xFF), KEYP_TIMEOUT_L) < 0)
                return -EIO;

        if (twl4030_kpwrite_u8(kp, (i >> 8), KEYP_TIMEOUT_H) < 0)
                return -EIO;

        /*
         * Enable Clear-on-Read; disable remembering events that fire
         * after the IRQ but before our handler acks (reads) them,
         */
        reg = TWL4030_SIH_CTRL_COR_MASK | TWL4030_SIH_CTRL_PENDDIS_MASK;
        if (twl4030_kpwrite_u8(kp, reg, KEYP_SIH_CTRL) < 0)
                return -EIO;

        /* initialize key state; irqs update it from here on */
        if (twl4030_read_kp_matrix_state(kp, kp->kp_state) < 0)
                return -EIO;

        return 0;
}

/*
 * Registers keypad device with input subsystem
 * and configures TWL4030 keypad registers
 */
static int twl4030_kp_probe(struct platform_device *pdev)
{
        struct twl4030_keypad_data *pdata = pdev->dev.platform_data;
        const struct matrix_keymap_data *keymap_data;
        struct twl4030_keypad *kp;
        struct input_dev *input;
        u8 reg;
        int error;

        if (!pdata || !pdata->rows || !pdata->cols || !pdata->keymap_data ||
            pdata->rows > TWL4030_MAX_ROWS || pdata->cols > TWL4030_MAX_COLS) {
                dev_err(&pdev->dev, "Invalid platform_data\n");
                return -EINVAL;
        }

        keymap_data = pdata->keymap_data;

        kp = kzalloc(sizeof(*kp), GFP_KERNEL);
        input = input_allocate_device();
        if (!kp || !input) {
                error = -ENOMEM;
                goto err1;
        }

        /* Get the debug Device */
        kp->dbg_dev = &pdev->dev;
        kp->input = input;

        kp->n_rows = pdata->rows;
        kp->n_cols = pdata->cols;
        kp->irq = platform_get_irq(pdev, 0);

        /* setup input device */
        input->name             = "TWL4030 Keypad";
        input->phys             = "twl4030_keypad/input0";
        input->dev.parent       = &pdev->dev;

        input->id.bustype       = BUS_HOST;
        input->id.vendor        = 0x0001;
        input->id.product       = 0x0001;
        input->id.version       = 0x0003;

        error = matrix_keypad_build_keymap(keymap_data, NULL,
                                           TWL4030_MAX_ROWS,
                                           1 << TWL4030_ROW_SHIFT,
                                           kp->keymap, input);
        if (error) {
                dev_err(kp->dbg_dev, "Failed to build keymap\n");
                goto err1;
        }

        input_set_capability(input, EV_MSC, MSC_SCAN);
        /* Enable auto repeat feature of Linux input subsystem */
        if (pdata->rep)
                __set_bit(EV_REP, input->evbit);

        error = input_register_device(input);
        if (error) {
                dev_err(kp->dbg_dev,
                        "Unable to register twl4030 keypad device\n");
                goto err1;
        }

        error = twl4030_kp_program(kp);
        if (error)
                goto err2;

        /*
         * This ISR will always execute in kernel thread context because of
         * the need to access the TWL4030 over the I2C bus.
         *
         * NOTE:  we assume this host is wired to TWL4040 INT1, not INT2 ...
         */
        error = request_threaded_irq(kp->irq, NULL, do_kp_irq,
                        0, pdev->name, kp);
        if (error) {
                dev_info(kp->dbg_dev, "request_irq failed for irq no=%d\n",
                        kp->irq);
                goto err2;
        }

        /* Enable KP and TO interrupts now. */
        reg = (u8) ~(KEYP_IMR1_KP | KEYP_IMR1_TO);
        if (twl4030_kpwrite_u8(kp, reg, KEYP_IMR1)) {
                error = -EIO;
                goto err3;
        }

        platform_set_drvdata(pdev, kp);
        return 0;

err3:
        /* mask all events - we don't care about the result */
        (void) twl4030_kpwrite_u8(kp, 0xff, KEYP_IMR1);
        free_irq(kp->irq, kp);
err2:
        input_unregister_device(input);
        input = NULL;
err1:
        input_free_device(input);
        kfree(kp);
        return error;
}

static int twl4030_kp_remove(struct platform_device *pdev)
{
        struct twl4030_keypad *kp = platform_get_drvdata(pdev);

        free_irq(kp->irq, kp);
        input_unregister_device(kp->input);
        kfree(kp);

        return 0;
}

/*
 * NOTE: twl4030 are multi-function devices connected via I2C.
 * So this device is a child of an I2C parent, thus it needs to
 * support unplug/replug (which most platform devices don't).
 */

static struct platform_driver twl4030_kp_driver = {
        .probe          = twl4030_kp_probe,
        .remove         = twl4030_kp_remove,
        .driver         = {
                .name   = "twl4030_keypad",
                .owner  = THIS_MODULE,
        },
};
module_platform_driver(twl4030_kp_driver);

MODULE_AUTHOR("Texas Instruments");
MODULE_DESCRIPTION("TWL4030 Keypad Driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:twl4030_keypad");