// SPDX-License-Identifier: GPL-2.0-only
// Copyright (C) 2014 Broadcom Corporation

#include <linux/bitops.h>
#include <linux/clk.h>
#include <linux/gfp.h>
#include <linux/io.h>
#include <linux/input.h>
#include <linux/input/matrix_keypad.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/stddef.h>
#include <linux/types.h>

#define DEFAULT_CLK_HZ                  31250
#define MAX_ROWS                        8
#define MAX_COLS                        8

/* Register/field definitions */
#define KPCR_OFFSET                     0x00000080
#define KPCR_MODE                       0x00000002
#define KPCR_MODE_SHIFT                 1
#define KPCR_MODE_MASK                  1
#define KPCR_ENABLE                     0x00000001
#define KPCR_STATUSFILTERENABLE         0x00008000
#define KPCR_STATUSFILTERTYPE_SHIFT     12
#define KPCR_COLFILTERENABLE            0x00000800
#define KPCR_COLFILTERTYPE_SHIFT        8
#define KPCR_ROWWIDTH_SHIFT             20
#define KPCR_COLUMNWIDTH_SHIFT          16

#define KPIOR_OFFSET                    0x00000084
#define KPIOR_ROWOCONTRL_SHIFT          24
#define KPIOR_ROWOCONTRL_MASK           0xFF000000
#define KPIOR_COLUMNOCONTRL_SHIFT       16
#define KPIOR_COLUMNOCONTRL_MASK        0x00FF0000
#define KPIOR_COLUMN_IO_DATA_SHIFT      0

#define KPEMR0_OFFSET                   0x00000090
#define KPEMR1_OFFSET                   0x00000094
#define KPEMR2_OFFSET                   0x00000098
#define KPEMR3_OFFSET                   0x0000009C
#define KPEMR_EDGETYPE_BOTH             3

#define KPSSR0_OFFSET                   0x000000A0
#define KPSSR1_OFFSET                   0x000000A4
#define KPSSRN_OFFSET(reg_n)            (KPSSR0_OFFSET + 4 * (reg_n))
#define KPIMR0_OFFSET                   0x000000B0
#define KPIMR1_OFFSET                   0x000000B4
#define KPICR0_OFFSET                   0x000000B8
#define KPICR1_OFFSET                   0x000000BC
#define KPICRN_OFFSET(reg_n)            (KPICR0_OFFSET + 4 * (reg_n))
#define KPISR0_OFFSET                   0x000000C0
#define KPISR1_OFFSET                   0x000000C4

#define KPCR_STATUSFILTERTYPE_MAX       7
#define KPCR_COLFILTERTYPE_MAX          7

/* Macros to determine the row/column from a bit that is set in SSR0/1. */
#define BIT_TO_ROW_SSRN(bit_nr, reg_n)  (((bit_nr) >> 3) + 4 * (reg_n))
#define BIT_TO_COL(bit_nr)              ((bit_nr) % 8)

/* Structure representing various run-time entities */
struct bcm_kp {
        void __iomem *base;
        int irq;
        struct clk *clk;
        struct input_dev *input_dev;
        unsigned long last_state[2];
        unsigned int n_rows;
        unsigned int n_cols;
        u32 kpcr;
        u32 kpior;
        u32 kpemr;
        u32 imr0_val;
        u32 imr1_val;
};

/*
 * Returns the keycode from the input device keymap given the row and
 * column.
 */
static int bcm_kp_get_keycode(struct bcm_kp *kp, int row, int col)
{
        unsigned int row_shift = get_count_order(kp->n_cols);
        unsigned short *keymap = kp->input_dev->keycode;

        return keymap[MATRIX_SCAN_CODE(row, col, row_shift)];
}

static void bcm_kp_report_keys(struct bcm_kp *kp, int reg_num, int pull_mode)
{
        unsigned long state, change;
        int bit_nr;
        int key_press;
        int row, col;
        unsigned int keycode;

        /* Clear interrupts */
        writel(0xFFFFFFFF, kp->base + KPICRN_OFFSET(reg_num));

        state = readl(kp->base + KPSSRN_OFFSET(reg_num));
        change = kp->last_state[reg_num] ^ state;
        kp->last_state[reg_num] = state;

        for_each_set_bit(bit_nr, &change, BITS_PER_LONG) {
                key_press = state & BIT(bit_nr);
                /* The meaning of SSR register depends on pull mode. */
                key_press = pull_mode ? !key_press : key_press;
                row = BIT_TO_ROW_SSRN(bit_nr, reg_num);
                col = BIT_TO_COL(bit_nr);
                keycode = bcm_kp_get_keycode(kp, row, col);
                input_report_key(kp->input_dev, keycode, key_press);
        }
}

static irqreturn_t bcm_kp_isr_thread(int irq, void *dev_id)
{
        struct bcm_kp *kp = dev_id;
        int pull_mode = (kp->kpcr >> KPCR_MODE_SHIFT) & KPCR_MODE_MASK;
        int reg_num;

        for (reg_num = 0; reg_num <= 1; reg_num++)
                bcm_kp_report_keys(kp, reg_num, pull_mode);

        input_sync(kp->input_dev);

        return IRQ_HANDLED;
}

static int bcm_kp_start(struct bcm_kp *kp)
{
        int error;

        if (kp->clk) {
                error = clk_prepare_enable(kp->clk);
                if (error)
                        return error;
        }

        writel(kp->kpior, kp->base + KPIOR_OFFSET);

        writel(kp->imr0_val, kp->base + KPIMR0_OFFSET);
        writel(kp->imr1_val, kp->base + KPIMR1_OFFSET);

        writel(kp->kpemr, kp->base + KPEMR0_OFFSET);
        writel(kp->kpemr, kp->base + KPEMR1_OFFSET);
        writel(kp->kpemr, kp->base + KPEMR2_OFFSET);
        writel(kp->kpemr, kp->base + KPEMR3_OFFSET);

        writel(0xFFFFFFFF, kp->base + KPICR0_OFFSET);
        writel(0xFFFFFFFF, kp->base + KPICR1_OFFSET);

        kp->last_state[0] = readl(kp->base + KPSSR0_OFFSET);
        kp->last_state[0] = readl(kp->base + KPSSR1_OFFSET);

        writel(kp->kpcr | KPCR_ENABLE, kp->base + KPCR_OFFSET);

        return 0;
}

static void bcm_kp_stop(const struct bcm_kp *kp)
{
        u32 val;

        val = readl(kp->base + KPCR_OFFSET);
        val &= ~KPCR_ENABLE;
        writel(0, kp->base + KPCR_OFFSET);
        writel(0, kp->base + KPIMR0_OFFSET);
        writel(0, kp->base + KPIMR1_OFFSET);
        writel(0xFFFFFFFF, kp->base + KPICR0_OFFSET);
        writel(0xFFFFFFFF, kp->base + KPICR1_OFFSET);

        clk_disable_unprepare(kp->clk);
}

static int bcm_kp_open(struct input_dev *dev)
{
        struct bcm_kp *kp = input_get_drvdata(dev);

        return bcm_kp_start(kp);
}

static void bcm_kp_close(struct input_dev *dev)
{
        struct bcm_kp *kp = input_get_drvdata(dev);

        bcm_kp_stop(kp);
}

static int bcm_kp_matrix_key_parse_dt(struct bcm_kp *kp)
{
        struct device *dev = kp->input_dev->dev.parent;
        struct device_node *np = dev->of_node;
        int error;
        unsigned int dt_val;
        unsigned int i;
        unsigned int num_rows, col_mask, rows_set;

        /* Initialize the KPCR Keypad Configuration Register */
        kp->kpcr = KPCR_STATUSFILTERENABLE | KPCR_COLFILTERENABLE;

        error = matrix_keypad_parse_properties(dev, &kp->n_rows, &kp->n_cols);
        if (error) {
                dev_err(dev, "failed to parse kp params\n");
                return error;
        }

        /* Set row width for the ASIC block. */
        kp->kpcr |= (kp->n_rows - 1) << KPCR_ROWWIDTH_SHIFT;

        /* Set column width for the ASIC block. */
        kp->kpcr |= (kp->n_cols - 1) << KPCR_COLUMNWIDTH_SHIFT;

        /* Configure the IMR registers */

        /*
         * IMR registers contain interrupt enable bits for 8x8 matrix
         * IMR0 register format: <row3> <row2> <row1> <row0>
         * IMR1 register format: <row7> <row6> <row5> <row4>
         */
        col_mask = (1 << (kp->n_cols)) - 1;
        num_rows = kp->n_rows;

        /* Set column bits in rows 0 to 3 in IMR0 */
        kp->imr0_val = col_mask;

        rows_set = 1;
        while (--num_rows && rows_set++ < 4)
                kp->imr0_val |= kp->imr0_val << MAX_COLS;

        /* Set column bits in rows 4 to 7 in IMR1 */
        kp->imr1_val = 0;
        if (num_rows) {
                kp->imr1_val = col_mask;
                while (--num_rows)
                        kp->imr1_val |= kp->imr1_val << MAX_COLS;
        }

        /* Initialize the KPEMR Keypress Edge Mode Registers */
        /* Trigger on both edges */
        kp->kpemr = 0;
        for (i = 0; i <= 30; i += 2)
                kp->kpemr |= (KPEMR_EDGETYPE_BOTH << i);

        /*
         * Obtain the Status filter debounce value and verify against the
         * possible values specified in the DT binding.
         */
        of_property_read_u32(np, "status-debounce-filter-period", &dt_val);

        if (dt_val > KPCR_STATUSFILTERTYPE_MAX) {
                dev_err(dev, "Invalid Status filter debounce value %d\n",
                        dt_val);
                return -EINVAL;
        }

        kp->kpcr |= dt_val << KPCR_STATUSFILTERTYPE_SHIFT;

        /*
         * Obtain the Column filter debounce value and verify against the
         * possible values specified in the DT binding.
         */
        of_property_read_u32(np, "col-debounce-filter-period", &dt_val);

        if (dt_val > KPCR_COLFILTERTYPE_MAX) {
                dev_err(dev, "Invalid Column filter debounce value %d\n",
                        dt_val);
                return -EINVAL;
        }

        kp->kpcr |= dt_val << KPCR_COLFILTERTYPE_SHIFT;

        /*
         * Determine between the row and column,
         * which should be configured as output.
         */
        if (of_property_read_bool(np, "row-output-enabled")) {
                /*
                * Set RowOContrl or ColumnOContrl in KPIOR
                * to the number of pins to drive as outputs
                */
                kp->kpior = ((1 << kp->n_rows) - 1) <<
                                KPIOR_ROWOCONTRL_SHIFT;
        } else {
                kp->kpior = ((1 << kp->n_cols) - 1) <<
                                KPIOR_COLUMNOCONTRL_SHIFT;
        }

        /*
         * Determine if the scan pull up needs to be enabled
         */
        if (of_property_read_bool(np, "pull-up-enabled"))
                kp->kpcr |= KPCR_MODE;

        dev_dbg(dev, "n_rows=%d n_col=%d kpcr=%x kpior=%x kpemr=%x\n",
                kp->n_rows, kp->n_cols,
                kp->kpcr, kp->kpior, kp->kpemr);

        return 0;
}


static int bcm_kp_probe(struct platform_device *pdev)
{
        struct bcm_kp *kp;
        struct input_dev *input_dev;
        int error;

        kp = devm_kzalloc(&pdev->dev, sizeof(*kp), GFP_KERNEL);
        if (!kp)
                return -ENOMEM;

        input_dev = devm_input_allocate_device(&pdev->dev);
        if (!input_dev) {
                dev_err(&pdev->dev, "failed to allocate the input device\n");
                return -ENOMEM;
        }

        __set_bit(EV_KEY, input_dev->evbit);

        /* Enable auto repeat feature of Linux input subsystem */
        if (of_property_read_bool(pdev->dev.of_node, "autorepeat"))
                __set_bit(EV_REP, input_dev->evbit);

        input_dev->name = pdev->name;
        input_dev->phys = "keypad/input0";
        input_dev->dev.parent = &pdev->dev;
        input_dev->open = bcm_kp_open;
        input_dev->close = bcm_kp_close;

        input_dev->id.bustype = BUS_HOST;
        input_dev->id.vendor = 0x0001;
        input_dev->id.product = 0x0001;
        input_dev->id.version = 0x0100;

        input_set_drvdata(input_dev, kp);

        kp->input_dev = input_dev;

        error = bcm_kp_matrix_key_parse_dt(kp);
        if (error)
                return error;

        error = matrix_keypad_build_keymap(NULL, NULL,
                                           kp->n_rows, kp->n_cols,
                                           NULL, input_dev);
        if (error) {
                dev_err(&pdev->dev, "failed to build keymap\n");
                return error;
        }

        kp->base = devm_platform_ioremap_resource(pdev, 0);
        if (IS_ERR(kp->base))
                return PTR_ERR(kp->base);

        /* Enable clock */
        kp->clk = devm_clk_get_optional(&pdev->dev, "peri_clk");
        if (IS_ERR(kp->clk)) {
                return dev_err_probe(&pdev->dev, PTR_ERR(kp->clk), "Failed to get clock\n");
        } else if (!kp->clk) {
                dev_dbg(&pdev->dev, "No clock specified. Assuming it's enabled\n");
        } else {
                unsigned int desired_rate;
                long actual_rate;

                error = of_property_read_u32(pdev->dev.of_node,
                                             "clock-frequency", &desired_rate);
                if (error < 0)
                        desired_rate = DEFAULT_CLK_HZ;

                actual_rate = clk_round_rate(kp->clk, desired_rate);
                if (actual_rate <= 0)
                        return -EINVAL;

                error = clk_set_rate(kp->clk, actual_rate);
                if (error)
                        return error;

                error = clk_prepare_enable(kp->clk);
                if (error)
                        return error;
        }

        /* Put the kp into a known sane state */
        bcm_kp_stop(kp);

        kp->irq = platform_get_irq(pdev, 0);
        if (kp->irq < 0)
                return -EINVAL;

        error = devm_request_threaded_irq(&pdev->dev, kp->irq,
                                          NULL, bcm_kp_isr_thread,
                                          IRQF_ONESHOT, pdev->name, kp);
        if (error) {
                dev_err(&pdev->dev, "failed to request IRQ\n");
                return error;
        }

        error = input_register_device(input_dev);
        if (error) {
                dev_err(&pdev->dev, "failed to register input device\n");
                return error;
        }

        return 0;
}

static const struct of_device_id bcm_kp_of_match[] = {
        { .compatible = "brcm,bcm-keypad" },
        { },
};
MODULE_DEVICE_TABLE(of, bcm_kp_of_match);

static struct platform_driver bcm_kp_device_driver = {
        .probe          = bcm_kp_probe,
        .driver         = {
                .name   = "bcm-keypad",
                .of_match_table = bcm_kp_of_match,
        }
};

module_platform_driver(bcm_kp_device_driver);

MODULE_AUTHOR("Broadcom Corporation");
MODULE_DESCRIPTION("BCM Keypad Driver");
MODULE_LICENSE("GPL v2");