// SPDX-License-Identifier: GPL-2.0-only
/*
 *  Copyright (C) 2013 Daniel Tang <tangrs@tangrs.id.au>
 */

#include <linux/input/matrix_keypad.h>
#include <linux/platform_device.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/delay.h>
#include <linux/input.h>
#include <linux/slab.h>
#include <linux/clk.h>
#include <linux/module.h>
#include <linux/of.h>

#define KEYPAD_SCAN_MODE        0x00
#define KEYPAD_CNTL             0x04
#define KEYPAD_INT              0x08
#define KEYPAD_INTMSK           0x0C

#define KEYPAD_DATA             0x10
#define KEYPAD_GPIO             0x30

#define KEYPAD_UNKNOWN_INT      0x40
#define KEYPAD_UNKNOWN_INT_STS  0x44

#define KEYPAD_BITMASK_COLS     11
#define KEYPAD_BITMASK_ROWS     8

struct nspire_keypad {
        void __iomem *reg_base;
        u32 int_mask;

        struct input_dev *input;
        struct clk *clk;

        struct matrix_keymap_data *keymap;
        int row_shift;

        /* Maximum delay estimated assuming 33MHz APB */
        u32 scan_interval;      /* In microseconds (~2000us max) */
        u32 row_delay;          /* In microseconds (~500us max) */

        u16 state[KEYPAD_BITMASK_ROWS];

        bool active_low;
};

static irqreturn_t nspire_keypad_irq(int irq, void *dev_id)
{
        struct nspire_keypad *keypad = dev_id;
        struct input_dev *input = keypad->input;
        unsigned short *keymap = input->keycode;
        unsigned int code;
        int row, col;
        u32 int_sts;
        u16 state[8];
        u16 bits, changed;

        int_sts = readl(keypad->reg_base + KEYPAD_INT) & keypad->int_mask;
        if (!int_sts)
                return IRQ_NONE;

        memcpy_fromio(state, keypad->reg_base + KEYPAD_DATA, sizeof(state));

        for (row = 0; row < KEYPAD_BITMASK_ROWS; row++) {
                bits = state[row];
                if (keypad->active_low)
                        bits = ~bits;

                changed = bits ^ keypad->state[row];
                if (!changed)
                        continue;

                keypad->state[row] = bits;

                for (col = 0; col < KEYPAD_BITMASK_COLS; col++) {
                        if (!(changed & (1U << col)))
                                continue;

                        code = MATRIX_SCAN_CODE(row, col, keypad->row_shift);
                        input_event(input, EV_MSC, MSC_SCAN, code);
                        input_report_key(input, keymap[code],
                                         bits & (1U << col));
                }
        }

        input_sync(input);

        writel(0x3, keypad->reg_base + KEYPAD_INT);

        return IRQ_HANDLED;
}

static int nspire_keypad_open(struct input_dev *input)
{
        struct nspire_keypad *keypad = input_get_drvdata(input);
        unsigned long val = 0, cycles_per_us, delay_cycles, row_delay_cycles;
        int error;

        error = clk_prepare_enable(keypad->clk);
        if (error)
                return error;

        cycles_per_us = (clk_get_rate(keypad->clk) / 1000000);
        if (cycles_per_us == 0)
                cycles_per_us = 1;

        delay_cycles = cycles_per_us * keypad->scan_interval;
        WARN_ON(delay_cycles >= (1 << 16)); /* Overflow */
        delay_cycles &= 0xffff;

        row_delay_cycles = cycles_per_us * keypad->row_delay;
        WARN_ON(row_delay_cycles >= (1 << 14)); /* Overflow */
        row_delay_cycles &= 0x3fff;

        val |= 3 << 0; /* Set scan mode to 3 (continuous scan) */
        val |= row_delay_cycles << 2; /* Delay between scanning each row */
        val |= delay_cycles << 16; /* Delay between scans */
        writel(val, keypad->reg_base + KEYPAD_SCAN_MODE);

        val = (KEYPAD_BITMASK_ROWS & 0xff) | (KEYPAD_BITMASK_COLS & 0xff)<<8;
        writel(val, keypad->reg_base + KEYPAD_CNTL);

        /* Enable interrupts */
        keypad->int_mask = 1 << 1;
        writel(keypad->int_mask, keypad->reg_base + KEYPAD_INTMSK);

        return 0;
}

static void nspire_keypad_close(struct input_dev *input)
{
        struct nspire_keypad *keypad = input_get_drvdata(input);

        /* Disable interrupts */
        writel(0, keypad->reg_base + KEYPAD_INTMSK);
        /* Acknowledge existing interrupts */
        writel(~0, keypad->reg_base + KEYPAD_INT);

        clk_disable_unprepare(keypad->clk);
}

static int nspire_keypad_probe(struct platform_device *pdev)
{
        const struct device_node *of_node = pdev->dev.of_node;
        struct nspire_keypad *keypad;
        struct input_dev *input;
        struct resource *res;
        int irq;
        int error;

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

        keypad = devm_kzalloc(&pdev->dev, sizeof(struct nspire_keypad),
                              GFP_KERNEL);
        if (!keypad) {
                dev_err(&pdev->dev, "failed to allocate keypad memory\n");
                return -ENOMEM;
        }

        keypad->row_shift = get_count_order(KEYPAD_BITMASK_COLS);

        error = of_property_read_u32(of_node, "scan-interval",
                                     &keypad->scan_interval);
        if (error) {
                dev_err(&pdev->dev, "failed to get scan-interval\n");
                return error;
        }

        error = of_property_read_u32(of_node, "row-delay",
                                     &keypad->row_delay);
        if (error) {
                dev_err(&pdev->dev, "failed to get row-delay\n");
                return error;
        }

        keypad->active_low = of_property_read_bool(of_node, "active-low");

        keypad->clk = devm_clk_get(&pdev->dev, NULL);
        if (IS_ERR(keypad->clk)) {
                dev_err(&pdev->dev, "unable to get clock\n");
                return PTR_ERR(keypad->clk);
        }

        keypad->reg_base = devm_platform_get_and_ioremap_resource(pdev, 0, &res);
        if (IS_ERR(keypad->reg_base))
                return PTR_ERR(keypad->reg_base);

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

        error = clk_prepare_enable(keypad->clk);
        if (error) {
                dev_err(&pdev->dev, "failed to enable clock\n");
                return error;
        }

        /* Disable interrupts */
        writel(0, keypad->reg_base + KEYPAD_INTMSK);
        /* Acknowledge existing interrupts */
        writel(~0, keypad->reg_base + KEYPAD_INT);

        /* Disable GPIO interrupts to prevent hanging on touchpad */
        /* Possibly used to detect touchpad events */
        writel(0, keypad->reg_base + KEYPAD_UNKNOWN_INT);
        /* Acknowledge existing GPIO interrupts */
        writel(~0, keypad->reg_base + KEYPAD_UNKNOWN_INT_STS);

        clk_disable_unprepare(keypad->clk);

        input_set_drvdata(input, keypad);

        input->id.bustype = BUS_HOST;
        input->name = "nspire-keypad";
        input->open = nspire_keypad_open;
        input->close = nspire_keypad_close;

        __set_bit(EV_KEY, input->evbit);
        __set_bit(EV_REP, input->evbit);
        input_set_capability(input, EV_MSC, MSC_SCAN);

        error = matrix_keypad_build_keymap(NULL, NULL,
                                           KEYPAD_BITMASK_ROWS,
                                           KEYPAD_BITMASK_COLS,
                                           NULL, input);
        if (error) {
                dev_err(&pdev->dev, "building keymap failed\n");
                return error;
        }

        error = devm_request_irq(&pdev->dev, irq, nspire_keypad_irq, 0,
                                 "nspire_keypad", keypad);
        if (error) {
                dev_err(&pdev->dev, "allocate irq %d failed\n", irq);
                return error;
        }

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

        dev_dbg(&pdev->dev,
                "TI-NSPIRE keypad at %pR (scan_interval=%uus, row_delay=%uus%s)\n",
                res, keypad->row_delay, keypad->scan_interval,
                keypad->active_low ? ", active_low" : "");

        return 0;
}

static const struct of_device_id nspire_keypad_dt_match[] = {
        { .compatible = "ti,nspire-keypad" },
        { },
};
MODULE_DEVICE_TABLE(of, nspire_keypad_dt_match);

static struct platform_driver nspire_keypad_driver = {
        .driver = {
                .name = "nspire-keypad",
                .of_match_table = nspire_keypad_dt_match,
        },
        .probe = nspire_keypad_probe,
};

module_platform_driver(nspire_keypad_driver);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("TI-NSPIRE Keypad Driver");