// SPDX-License-Identifier: GPL-2.0-only
/*
 * STMicroelectronics uvis25 sensor driver
 *
 * Copyright 2017 STMicroelectronics Inc.
 *
 * Lorenzo Bianconi <lorenzo.bianconi83@gmail.com>
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/device.h>
#include <linux/iio/sysfs.h>
#include <linux/delay.h>
#include <linux/pm.h>
#include <linux/interrupt.h>
#include <linux/irqreturn.h>
#include <linux/iio/trigger.h>
#include <linux/iio/trigger_consumer.h>
#include <linux/iio/triggered_buffer.h>
#include <linux/iio/buffer.h>
#include <linux/regmap.h>

#include "st_uvis25.h"

#define ST_UVIS25_REG_WHOAMI_ADDR       0x0f
#define ST_UVIS25_REG_WHOAMI_VAL        0xca
#define ST_UVIS25_REG_CTRL1_ADDR        0x20
#define ST_UVIS25_REG_ODR_MASK          BIT(0)
#define ST_UVIS25_REG_BDU_MASK          BIT(1)
#define ST_UVIS25_REG_CTRL2_ADDR        0x21
#define ST_UVIS25_REG_BOOT_MASK         BIT(7)
#define ST_UVIS25_REG_CTRL3_ADDR        0x22
#define ST_UVIS25_REG_HL_MASK           BIT(7)
#define ST_UVIS25_REG_STATUS_ADDR       0x27
#define ST_UVIS25_REG_UV_DA_MASK        BIT(0)
#define ST_UVIS25_REG_OUT_ADDR          0x28

static const struct iio_chan_spec st_uvis25_channels[] = {
        {
                .type = IIO_UVINDEX,
                .address = ST_UVIS25_REG_OUT_ADDR,
                .info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
                .scan_index = 0,
                .scan_type = {
                        .sign = 'u',
                        .realbits = 8,
                        .storagebits = 8,
                },
        },
        IIO_CHAN_SOFT_TIMESTAMP(1),
};

static int st_uvis25_check_whoami(struct st_uvis25_hw *hw)
{
        int err, data;

        err = regmap_read(hw->regmap, ST_UVIS25_REG_WHOAMI_ADDR, &data);
        if (err < 0) {
                dev_err(regmap_get_device(hw->regmap),
                        "failed to read whoami register\n");
                return err;
        }

        if (data != ST_UVIS25_REG_WHOAMI_VAL) {
                dev_err(regmap_get_device(hw->regmap),
                        "wrong whoami {%02x vs %02x}\n",
                        data, ST_UVIS25_REG_WHOAMI_VAL);
                return -ENODEV;
        }

        return 0;
}

static int st_uvis25_set_enable(struct st_uvis25_hw *hw, bool enable)
{
        int err;

        err = regmap_update_bits(hw->regmap, ST_UVIS25_REG_CTRL1_ADDR,
                                 ST_UVIS25_REG_ODR_MASK, enable);
        if (err < 0)
                return err;

        hw->enabled = enable;

        return 0;
}

static int st_uvis25_read_oneshot(struct st_uvis25_hw *hw, u8 addr, int *val)
{
        int err;

        err = st_uvis25_set_enable(hw, true);
        if (err < 0)
                return err;

        msleep(1500);

        /*
         * in order to avoid possible race conditions with interrupt
         * generation, disable the sensor first and then poll output
         * register. That sequence guarantees the interrupt will be reset
         * when irq line is unmasked
         */
        err = st_uvis25_set_enable(hw, false);
        if (err < 0)
                return err;

        err = regmap_read(hw->regmap, addr, val);

        return err < 0 ? err : IIO_VAL_INT;
}

static int st_uvis25_read_raw(struct iio_dev *iio_dev,
                              struct iio_chan_spec const *ch,
                              int *val, int *val2, long mask)
{
        int ret;

        if (!iio_device_claim_direct(iio_dev))
                return -EBUSY;

        switch (mask) {
        case IIO_CHAN_INFO_PROCESSED: {
                struct st_uvis25_hw *hw = iio_priv(iio_dev);

                /*
                 * mask irq line during oneshot read since the sensor
                 * does not export the capability to disable data-ready line
                 * in the register map and it is enabled by default.
                 * If the line is unmasked during read_raw() it will be set
                 * active and never reset since the trigger is disabled
                 */
                if (hw->irq > 0)
                        disable_irq(hw->irq);
                ret = st_uvis25_read_oneshot(hw, ch->address, val);
                if (hw->irq > 0)
                        enable_irq(hw->irq);
                break;
        }
        default:
                ret = -EINVAL;
                break;
        }

        iio_device_release_direct(iio_dev);

        return ret;
}

static irqreturn_t st_uvis25_trigger_handler_thread(int irq, void *private)
{
        struct st_uvis25_hw *hw = private;
        int err, status;

        err = regmap_read(hw->regmap, ST_UVIS25_REG_STATUS_ADDR, &status);
        if (err < 0)
                return IRQ_HANDLED;

        if (!(status & ST_UVIS25_REG_UV_DA_MASK))
                return IRQ_NONE;

        iio_trigger_poll_nested(hw->trig);

        return IRQ_HANDLED;
}

static int st_uvis25_allocate_trigger(struct iio_dev *iio_dev)
{
        struct st_uvis25_hw *hw = iio_priv(iio_dev);
        struct device *dev = regmap_get_device(hw->regmap);
        bool irq_active_low = false;
        unsigned long irq_type;
        int err;

        irq_type = irq_get_trigger_type(hw->irq);
        switch (irq_type) {
        case IRQF_TRIGGER_HIGH:
        case IRQF_TRIGGER_RISING:
                break;
        case IRQF_TRIGGER_LOW:
        case IRQF_TRIGGER_FALLING:
                irq_active_low = true;
                break;
        default:
                dev_info(dev, "mode %lx unsupported\n", irq_type);
                return -EINVAL;
        }

        err = regmap_update_bits(hw->regmap, ST_UVIS25_REG_CTRL3_ADDR,
                                 ST_UVIS25_REG_HL_MASK, irq_active_low);
        if (err < 0)
                return err;

        err = devm_request_threaded_irq(dev, hw->irq, NULL,
                                        st_uvis25_trigger_handler_thread,
                                        irq_type | IRQF_ONESHOT,
                                        iio_dev->name, hw);
        if (err) {
                dev_err(dev, "failed to request trigger irq %d\n",
                        hw->irq);
                return err;
        }

        hw->trig = devm_iio_trigger_alloc(dev, "%s-trigger",
                                          iio_dev->name);
        if (!hw->trig)
                return -ENOMEM;

        iio_trigger_set_drvdata(hw->trig, iio_dev);

        return devm_iio_trigger_register(dev, hw->trig);
}

static int st_uvis25_buffer_preenable(struct iio_dev *iio_dev)
{
        return st_uvis25_set_enable(iio_priv(iio_dev), true);
}

static int st_uvis25_buffer_postdisable(struct iio_dev *iio_dev)
{
        return st_uvis25_set_enable(iio_priv(iio_dev), false);
}

static const struct iio_buffer_setup_ops st_uvis25_buffer_ops = {
        .preenable = st_uvis25_buffer_preenable,
        .postdisable = st_uvis25_buffer_postdisable,
};

static irqreturn_t st_uvis25_buffer_handler_thread(int irq, void *p)
{
        struct iio_poll_func *pf = p;
        struct iio_dev *iio_dev = pf->indio_dev;
        struct st_uvis25_hw *hw = iio_priv(iio_dev);
        unsigned int val;
        int err;
        /* Ensure timestamp is naturally aligned */
        struct {
                u8 chan;
                aligned_s64 ts;
        } scan = { };


        err = regmap_read(hw->regmap, ST_UVIS25_REG_OUT_ADDR, &val);
        if (err < 0)
                goto out;

        scan.chan = val;

        iio_push_to_buffers_with_ts(iio_dev, &scan, sizeof(scan),
                                    iio_get_time_ns(iio_dev));

out:
        iio_trigger_notify_done(hw->trig);

        return IRQ_HANDLED;
}

static int st_uvis25_allocate_buffer(struct iio_dev *iio_dev)
{
        struct st_uvis25_hw *hw = iio_priv(iio_dev);

        return devm_iio_triggered_buffer_setup(regmap_get_device(hw->regmap),
                                               iio_dev, NULL,
                                               st_uvis25_buffer_handler_thread,
                                               &st_uvis25_buffer_ops);
}

static const struct iio_info st_uvis25_info = {
        .read_raw = st_uvis25_read_raw,
};

static int st_uvis25_init_sensor(struct st_uvis25_hw *hw)
{
        int err;

        err = regmap_update_bits(hw->regmap, ST_UVIS25_REG_CTRL2_ADDR,
                                 ST_UVIS25_REG_BOOT_MASK, 1);
        if (err < 0)
                return err;

        msleep(2000);

        return regmap_update_bits(hw->regmap, ST_UVIS25_REG_CTRL1_ADDR,
                                  ST_UVIS25_REG_BDU_MASK, 1);
}

int st_uvis25_probe(struct device *dev, int irq, struct regmap *regmap)
{
        struct st_uvis25_hw *hw;
        struct iio_dev *iio_dev;
        int err;

        iio_dev = devm_iio_device_alloc(dev, sizeof(*hw));
        if (!iio_dev)
                return -ENOMEM;

        dev_set_drvdata(dev, iio_dev);

        hw = iio_priv(iio_dev);
        hw->irq = irq;
        hw->regmap = regmap;

        err = st_uvis25_check_whoami(hw);
        if (err < 0)
                return err;

        iio_dev->modes = INDIO_DIRECT_MODE;
        iio_dev->channels = st_uvis25_channels;
        iio_dev->num_channels = ARRAY_SIZE(st_uvis25_channels);
        iio_dev->name = ST_UVIS25_DEV_NAME;
        iio_dev->info = &st_uvis25_info;

        err = st_uvis25_init_sensor(hw);
        if (err < 0)
                return err;

        if (hw->irq > 0) {
                err = st_uvis25_allocate_buffer(iio_dev);
                if (err < 0)
                        return err;

                err = st_uvis25_allocate_trigger(iio_dev);
                if (err)
                        return err;
        }

        return devm_iio_device_register(dev, iio_dev);
}
EXPORT_SYMBOL_NS(st_uvis25_probe, "IIO_UVIS25");

static int st_uvis25_suspend(struct device *dev)
{
        struct iio_dev *iio_dev = dev_get_drvdata(dev);
        struct st_uvis25_hw *hw = iio_priv(iio_dev);

        return regmap_clear_bits(hw->regmap, ST_UVIS25_REG_CTRL1_ADDR,
                                 ST_UVIS25_REG_ODR_MASK);
}

static int st_uvis25_resume(struct device *dev)
{
        struct iio_dev *iio_dev = dev_get_drvdata(dev);
        struct st_uvis25_hw *hw = iio_priv(iio_dev);

        if (hw->enabled)
                return regmap_update_bits(hw->regmap, ST_UVIS25_REG_CTRL1_ADDR,
                                          ST_UVIS25_REG_ODR_MASK, 1);

        return 0;
}

EXPORT_NS_SIMPLE_DEV_PM_OPS(st_uvis25_pm_ops, st_uvis25_suspend, st_uvis25_resume, IIO_UVIS25);

MODULE_AUTHOR("Lorenzo Bianconi <lorenzo.bianconi83@gmail.com>");
MODULE_DESCRIPTION("STMicroelectronics uvis25 sensor driver");
MODULE_LICENSE("GPL v2");