/*
 * Driver for Mediatek IR Receiver Controller
 *
 * Copyright (C) 2017 Sean Wang <sean.wang@mediatek.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.
 */

#include <linux/clk.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/of_platform.h>
#include <linux/reset.h>
#include <media/rc-core.h>

#define MTK_IR_DEV KBUILD_MODNAME

/* Register to enable PWM and IR */
#define MTK_CONFIG_HIGH_REG       0x0c

/* Bit to enable IR pulse width detection */
#define MTK_PWM_EN                BIT(13)

/*
 * Register to setting ok count whose unit based on hardware sampling period
 * indicating IR receiving completion and then making IRQ fires
 */
#define MTK_OK_COUNT(x)           (((x) & GENMASK(23, 16)) << 16)

/* Bit to enable IR hardware function */
#define MTK_IR_EN                 BIT(0)

/* Bit to restart IR receiving */
#define MTK_IRCLR                 BIT(0)

/* Fields containing pulse width data */
#define MTK_WIDTH_MASK            (GENMASK(7, 0))

/* Bit to enable interrupt */
#define MTK_IRINT_EN              BIT(0)

/* Bit to clear interrupt status */
#define MTK_IRINT_CLR             BIT(0)

/* Maximum count of samples */
#define MTK_MAX_SAMPLES           0xff
/* Indicate the end of IR message */
#define MTK_IR_END(v, p)          ((v) == MTK_MAX_SAMPLES && (p) == 0)
/* Number of registers to record the pulse width */
#define MTK_CHKDATA_SZ            17
/* Sample period in ns */
#define MTK_IR_SAMPLE             46000

enum mtk_fields {
        /* Register to setting software sampling period */
        MTK_CHK_PERIOD,
        /* Register to setting hardware sampling period */
        MTK_HW_PERIOD,
};

enum mtk_regs {
        /* Register to clear state of state machine */
        MTK_IRCLR_REG,
        /* Register containing pulse width data */
        MTK_CHKDATA_REG,
        /* Register to enable IR interrupt */
        MTK_IRINT_EN_REG,
        /* Register to ack IR interrupt */
        MTK_IRINT_CLR_REG
};

static const u32 mt7623_regs[] = {
        [MTK_IRCLR_REG] =       0x20,
        [MTK_CHKDATA_REG] =     0x88,
        [MTK_IRINT_EN_REG] =    0xcc,
        [MTK_IRINT_CLR_REG] =   0xd0,
};

static const u32 mt7622_regs[] = {
        [MTK_IRCLR_REG] =       0x18,
        [MTK_CHKDATA_REG] =     0x30,
        [MTK_IRINT_EN_REG] =    0x1c,
        [MTK_IRINT_CLR_REG] =   0x20,
};

struct mtk_field_type {
        u32 reg;
        u8 offset;
        u32 mask;
};

/*
 * struct mtk_ir_data - This is the structure holding all differences among
                        various hardwares
 * @regs:               The pointer to the array holding registers offset
 * @fields:             The pointer to the array holding fields location
 * @div:                The internal divisor for the based reference clock
 * @ok_count:           The count indicating the completion of IR data
 *                      receiving when count is reached
 * @hw_period:          The value indicating the hardware sampling period
 */
struct mtk_ir_data {
        const u32 *regs;
        const struct mtk_field_type *fields;
        u8 div;
        u8 ok_count;
        u32 hw_period;
};

static const struct mtk_field_type mt7623_fields[] = {
        [MTK_CHK_PERIOD] = {0x10, 8, GENMASK(20, 8)},
        [MTK_HW_PERIOD] = {0x10, 0, GENMASK(7, 0)},
};

static const struct mtk_field_type mt7622_fields[] = {
        [MTK_CHK_PERIOD] = {0x24, 0, GENMASK(24, 0)},
        [MTK_HW_PERIOD] = {0x10, 0, GENMASK(24, 0)},
};

/*
 * struct mtk_ir -      This is the main datasructure for holding the state
 *                      of the driver
 * @dev:                The device pointer
 * @rc:                 The rc instrance
 * @base:               The mapped register i/o base
 * @irq:                The IRQ that we are using
 * @clk:                The clock that IR internal is using
 * @bus:                The clock that software decoder is using
 * @data:               Holding specific data for vaious platform
 */
struct mtk_ir {
        struct device   *dev;
        struct rc_dev   *rc;
        void __iomem    *base;
        int             irq;
        struct clk      *clk;
        struct clk      *bus;
        const struct mtk_ir_data *data;
};

static inline u32 mtk_chkdata_reg(struct mtk_ir *ir, u32 i)
{
        return ir->data->regs[MTK_CHKDATA_REG] + 4 * i;
}

static inline u32 mtk_chk_period(struct mtk_ir *ir)
{
        u32 val;

        /* Period of raw software sampling in ns */
        val = DIV_ROUND_CLOSEST(1000000000ul,
                                clk_get_rate(ir->bus) / ir->data->div);

        /*
         * Period for software decoder used in the
         * unit of raw software sampling
         */
        val = DIV_ROUND_CLOSEST(MTK_IR_SAMPLE, val);

        dev_dbg(ir->dev, "@pwm clk  = \t%lu\n",
                clk_get_rate(ir->bus) / ir->data->div);
        dev_dbg(ir->dev, "@chkperiod = %08x\n", val);

        return val;
}

static void mtk_w32_mask(struct mtk_ir *ir, u32 val, u32 mask, unsigned int reg)
{
        u32 tmp;

        tmp = __raw_readl(ir->base + reg);
        tmp = (tmp & ~mask) | val;
        __raw_writel(tmp, ir->base + reg);
}

static void mtk_w32(struct mtk_ir *ir, u32 val, unsigned int reg)
{
        __raw_writel(val, ir->base + reg);
}

static u32 mtk_r32(struct mtk_ir *ir, unsigned int reg)
{
        return __raw_readl(ir->base + reg);
}

static inline void mtk_irq_disable(struct mtk_ir *ir, u32 mask)
{
        u32 val;

        val = mtk_r32(ir, ir->data->regs[MTK_IRINT_EN_REG]);
        mtk_w32(ir, val & ~mask, ir->data->regs[MTK_IRINT_EN_REG]);
}

static inline void mtk_irq_enable(struct mtk_ir *ir, u32 mask)
{
        u32 val;

        val = mtk_r32(ir, ir->data->regs[MTK_IRINT_EN_REG]);
        mtk_w32(ir, val | mask, ir->data->regs[MTK_IRINT_EN_REG]);
}

static irqreturn_t mtk_ir_irq(int irqno, void *dev_id)
{
        struct mtk_ir *ir = dev_id;
        u8  wid = 0;
        u32 i, j, val;
        DEFINE_IR_RAW_EVENT(rawir);

        /*
         * Reset decoder state machine explicitly is required
         * because 1) the longest duration for space MTK IR hardware
         * could record is not safely long. e.g  12ms if rx resolution
         * is 46us by default. There is still the risk to satisfying
         * every decoder to reset themselves through long enough
         * trailing spaces and 2) the IRQ handler guarantees that
         * start of IR message is always contained in and starting
         * from register mtk_chkdata_reg(ir, i).
         */
        ir_raw_event_reset(ir->rc);

        /* First message must be pulse */
        rawir.pulse = false;

        /* Handle all pulse and space IR controller captures */
        for (i = 0 ; i < MTK_CHKDATA_SZ ; i++) {
                val = mtk_r32(ir, mtk_chkdata_reg(ir, i));
                dev_dbg(ir->dev, "@reg%d=0x%08x\n", i, val);

                for (j = 0 ; j < 4 ; j++) {
                        wid = (val & (MTK_WIDTH_MASK << j * 8)) >> j * 8;
                        rawir.pulse = !rawir.pulse;
                        rawir.duration = wid * (MTK_IR_SAMPLE + 1);
                        ir_raw_event_store_with_filter(ir->rc, &rawir);
                }
        }

        /*
         * The maximum number of edges the IR controller can
         * hold is MTK_CHKDATA_SZ * 4. So if received IR messages
         * is over the limit, the last incomplete IR message would
         * be appended trailing space and still would be sent into
         * ir-rc-raw to decode. That helps it is possible that it
         * has enough information to decode a scancode even if the
         * trailing end of the message is missing.
         */
        if (!MTK_IR_END(wid, rawir.pulse)) {
                rawir.pulse = false;
                rawir.duration = MTK_MAX_SAMPLES * (MTK_IR_SAMPLE + 1);
                ir_raw_event_store_with_filter(ir->rc, &rawir);
        }

        ir_raw_event_handle(ir->rc);

        /*
         * Restart controller for the next receive that would
         * clear up all CHKDATA registers
         */
        mtk_w32_mask(ir, 0x1, MTK_IRCLR, ir->data->regs[MTK_IRCLR_REG]);

        /* Clear interrupt status */
        mtk_w32_mask(ir, 0x1, MTK_IRINT_CLR,
                     ir->data->regs[MTK_IRINT_CLR_REG]);

        return IRQ_HANDLED;
}

static const struct mtk_ir_data mt7623_data = {
        .regs = mt7623_regs,
        .fields = mt7623_fields,
        .ok_count = 0xf,
        .hw_period = 0xff,
        .div    = 4,
};

static const struct mtk_ir_data mt7622_data = {
        .regs = mt7622_regs,
        .fields = mt7622_fields,
        .ok_count = 0xf,
        .hw_period = 0xffff,
        .div    = 32,
};

static const struct of_device_id mtk_ir_match[] = {
        { .compatible = "mediatek,mt7623-cir", .data = &mt7623_data},
        { .compatible = "mediatek,mt7622-cir", .data = &mt7622_data},
        {},
};
MODULE_DEVICE_TABLE(of, mtk_ir_match);

static int mtk_ir_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct device_node *dn = dev->of_node;
        struct resource *res;
        struct mtk_ir *ir;
        u32 val;
        int ret = 0;
        const char *map_name;

        ir = devm_kzalloc(dev, sizeof(struct mtk_ir), GFP_KERNEL);
        if (!ir)
                return -ENOMEM;

        ir->dev = dev;
        ir->data = of_device_get_match_data(dev);

        ir->clk = devm_clk_get(dev, "clk");
        if (IS_ERR(ir->clk)) {
                dev_err(dev, "failed to get a ir clock.\n");
                return PTR_ERR(ir->clk);
        }

        ir->bus = devm_clk_get(dev, "bus");
        if (IS_ERR(ir->bus)) {
                /*
                 * For compatibility with older device trees try unnamed
                 * ir->bus uses the same clock as ir->clock.
                 */
                ir->bus = ir->clk;
        }

        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        ir->base = devm_ioremap_resource(dev, res);
        if (IS_ERR(ir->base)) {
                dev_err(dev, "failed to map registers\n");
                return PTR_ERR(ir->base);
        }

        ir->rc = devm_rc_allocate_device(dev, RC_DRIVER_IR_RAW);
        if (!ir->rc) {
                dev_err(dev, "failed to allocate device\n");
                return -ENOMEM;
        }

        ir->rc->priv = ir;
        ir->rc->device_name = MTK_IR_DEV;
        ir->rc->input_phys = MTK_IR_DEV "/input0";
        ir->rc->input_id.bustype = BUS_HOST;
        ir->rc->input_id.vendor = 0x0001;
        ir->rc->input_id.product = 0x0001;
        ir->rc->input_id.version = 0x0001;
        map_name = of_get_property(dn, "linux,rc-map-name", NULL);
        ir->rc->map_name = map_name ?: RC_MAP_EMPTY;
        ir->rc->dev.parent = dev;
        ir->rc->driver_name = MTK_IR_DEV;
        ir->rc->allowed_protocols = RC_PROTO_BIT_ALL;
        ir->rc->rx_resolution = MTK_IR_SAMPLE;
        ir->rc->timeout = MTK_MAX_SAMPLES * (MTK_IR_SAMPLE + 1);

        ret = devm_rc_register_device(dev, ir->rc);
        if (ret) {
                dev_err(dev, "failed to register rc device\n");
                return ret;
        }

        platform_set_drvdata(pdev, ir);

        ir->irq = platform_get_irq(pdev, 0);
        if (ir->irq < 0) {
                dev_err(dev, "no irq resource\n");
                return -ENODEV;
        }

        if (clk_prepare_enable(ir->clk)) {
                dev_err(dev, "try to enable ir_clk failed\n");
                return -EINVAL;
        }

        if (clk_prepare_enable(ir->bus)) {
                dev_err(dev, "try to enable ir_clk failed\n");
                ret = -EINVAL;
                goto exit_clkdisable_clk;
        }

        /*
         * Enable interrupt after proper hardware
         * setup and IRQ handler registration
         */
        mtk_irq_disable(ir, MTK_IRINT_EN);

        ret = devm_request_irq(dev, ir->irq, mtk_ir_irq, 0, MTK_IR_DEV, ir);
        if (ret) {
                dev_err(dev, "failed request irq\n");
                goto exit_clkdisable_bus;
        }

        /*
         * Setup software sample period as the reference of software decoder
         */
        val = (mtk_chk_period(ir) << ir->data->fields[MTK_CHK_PERIOD].offset) &
               ir->data->fields[MTK_CHK_PERIOD].mask;
        mtk_w32_mask(ir, val, ir->data->fields[MTK_CHK_PERIOD].mask,
                     ir->data->fields[MTK_CHK_PERIOD].reg);

        /*
         * Setup hardware sampling period used to setup the proper timeout for
         * indicating end of IR receiving completion
         */
        val = (ir->data->hw_period << ir->data->fields[MTK_HW_PERIOD].offset) &
               ir->data->fields[MTK_HW_PERIOD].mask;
        mtk_w32_mask(ir, val, ir->data->fields[MTK_HW_PERIOD].mask,
                     ir->data->fields[MTK_HW_PERIOD].reg);

        /* Enable IR and PWM */
        val = mtk_r32(ir, MTK_CONFIG_HIGH_REG);
        val |= MTK_OK_COUNT(ir->data->ok_count) |  MTK_PWM_EN | MTK_IR_EN;
        mtk_w32(ir, val, MTK_CONFIG_HIGH_REG);

        mtk_irq_enable(ir, MTK_IRINT_EN);

        dev_info(dev, "Initialized MT7623 IR driver, sample period = %dus\n",
                 DIV_ROUND_CLOSEST(MTK_IR_SAMPLE, 1000));

        return 0;

exit_clkdisable_bus:
        clk_disable_unprepare(ir->bus);
exit_clkdisable_clk:
        clk_disable_unprepare(ir->clk);

        return ret;
}

static int mtk_ir_remove(struct platform_device *pdev)
{
        struct mtk_ir *ir = platform_get_drvdata(pdev);

        /*
         * Avoid contention between remove handler and
         * IRQ handler so that disabling IR interrupt and
         * waiting for pending IRQ handler to complete
         */
        mtk_irq_disable(ir, MTK_IRINT_EN);
        synchronize_irq(ir->irq);

        clk_disable_unprepare(ir->bus);
        clk_disable_unprepare(ir->clk);

        return 0;
}

static struct platform_driver mtk_ir_driver = {
        .probe          = mtk_ir_probe,
        .remove         = mtk_ir_remove,
        .driver = {
                .name = MTK_IR_DEV,
                .of_match_table = mtk_ir_match,
        },
};

module_platform_driver(mtk_ir_driver);

MODULE_DESCRIPTION("Mediatek IR Receiver Controller Driver");
MODULE_AUTHOR("Sean Wang <sean.wang@mediatek.com>");
MODULE_LICENSE("GPL");