// SPDX-License-Identifier: GPL-2.0
// SPI driven IR LED device driver
//
// Copyright (c) 2016 Samsung Electronics Co., Ltd.
// Copyright (c) Andi Shyti <andi@etezian.org>

#include <linux/bits.h>
#include <linux/device.h>
#include <linux/err.h>
#include <linux/math.h>
#include <linux/mod_devicetable.h>
#include <linux/module.h>
#include <linux/property.h>
#include <linux/regulator/consumer.h>
#include <linux/spi/spi.h>
#include <linux/string.h>
#include <linux/types.h>

#include <media/rc-core.h>

#define IR_SPI_DRIVER_NAME              "ir-spi"

#define IR_SPI_DEFAULT_FREQUENCY        38000
#define IR_SPI_BITS_PER_PULSE           16

struct ir_spi_data {
        u32 freq;
        bool negated;

        u16 pulse;
        u16 space;

        struct rc_dev *rc;
        struct spi_device *spi;
        struct regulator *regulator;
};

static int ir_spi_tx(struct rc_dev *dev, unsigned int *buffer, unsigned int count)
{
        int i;
        int ret;
        unsigned int len = 0;
        struct ir_spi_data *idata = dev->priv;
        struct spi_transfer xfer;
        u16 *tx_buf;

        /* convert the pulse/space signal to raw binary signal */
        for (i = 0; i < count; i++) {
                buffer[i] = DIV_ROUND_CLOSEST_ULL((u64)buffer[i] * idata->freq,
                                                  1000000);
                len += buffer[i];
        }

        tx_buf = kmalloc_array(len, sizeof(*tx_buf), GFP_KERNEL);
        if (!tx_buf)
                return -ENOMEM;

        len = 0;
        for (i = 0; i < count; i++) {
                int j;
                u16 val;

                /*
                 * The first value in buffer is a pulse, so that 0, 2, 4, ...
                 * contain a pulse duration. On the contrary, 1, 3, 5, ...
                 * contain a space duration.
                 */
                val = (i % 2) ? idata->space : idata->pulse;
                for (j = 0; j < buffer[i]; j++)
                        tx_buf[len++] = val;
        }

        memset(&xfer, 0, sizeof(xfer));

        xfer.speed_hz = idata->freq * IR_SPI_BITS_PER_PULSE;
        xfer.len = len * sizeof(*tx_buf);
        xfer.tx_buf = tx_buf;

        ret = regulator_enable(idata->regulator);
        if (ret)
                goto err_free_tx_buf;

        ret = spi_sync_transfer(idata->spi, &xfer, 1);
        if (ret)
                dev_err(&idata->spi->dev, "unable to deliver the signal\n");

        regulator_disable(idata->regulator);

err_free_tx_buf:

        kfree(tx_buf);

        return ret ? ret : count;
}

static int ir_spi_set_tx_carrier(struct rc_dev *dev, u32 carrier)
{
        struct ir_spi_data *idata = dev->priv;

        if (!carrier)
                return -EINVAL;

        if (carrier > idata->spi->max_speed_hz / IR_SPI_BITS_PER_PULSE)
                return -EINVAL;

        idata->freq = carrier;

        return 0;
}

static int ir_spi_set_duty_cycle(struct rc_dev *dev, u32 duty_cycle)
{
        struct ir_spi_data *idata = dev->priv;
        int bits = (duty_cycle * 15) / 100;

        idata->pulse = GENMASK(bits, 0);

        if (idata->negated) {
                idata->pulse = ~idata->pulse;
                idata->space = 0xffff;
        } else {
                idata->space = 0;
        }

        return 0;
}

static int ir_spi_probe(struct spi_device *spi)
{
        struct device *dev = &spi->dev;
        int ret;
        u8 dc;
        struct ir_spi_data *idata;

        idata = devm_kzalloc(dev, sizeof(*idata), GFP_KERNEL);
        if (!idata)
                return -ENOMEM;

        idata->regulator = devm_regulator_get(dev, "irda_regulator");
        if (IS_ERR(idata->regulator))
                return PTR_ERR(idata->regulator);

        idata->rc = devm_rc_allocate_device(&spi->dev, RC_DRIVER_IR_RAW_TX);
        if (!idata->rc)
                return -ENOMEM;

        idata->rc->tx_ir           = ir_spi_tx;
        idata->rc->s_tx_carrier    = ir_spi_set_tx_carrier;
        idata->rc->s_tx_duty_cycle = ir_spi_set_duty_cycle;
        idata->rc->device_name     = "IR SPI";
        idata->rc->driver_name     = IR_SPI_DRIVER_NAME;
        idata->rc->priv            = idata;
        idata->spi                 = spi;

        idata->negated = device_property_read_bool(dev, "led-active-low");
        ret = device_property_read_u8(dev, "duty-cycle", &dc);
        if (ret)
                dc = 50;

        /*
         * ir_spi_set_duty_cycle() cannot fail, it returns int
         * to be compatible with the rc->s_tx_duty_cycle function.
         */
        ir_spi_set_duty_cycle(idata->rc, dc);

        idata->freq = IR_SPI_DEFAULT_FREQUENCY;

        return devm_rc_register_device(dev, idata->rc);
}

static const struct of_device_id ir_spi_of_match[] = {
        { .compatible = "ir-spi-led" },
        {}
};
MODULE_DEVICE_TABLE(of, ir_spi_of_match);

static const struct spi_device_id ir_spi_ids[] = {
        { "ir-spi-led" },
        {}
};
MODULE_DEVICE_TABLE(spi, ir_spi_ids);

static struct spi_driver ir_spi_driver = {
        .probe = ir_spi_probe,
        .id_table = ir_spi_ids,
        .driver = {
                .name = IR_SPI_DRIVER_NAME,
                .of_match_table = ir_spi_of_match,
        },
};
module_spi_driver(ir_spi_driver);

MODULE_AUTHOR("Andi Shyti <andi@etezian.org>");
MODULE_DESCRIPTION("SPI IR LED");
MODULE_LICENSE("GPL v2");