// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *      w1_ds2405.c
 *
 * Copyright (c) 2017 Maciej S. Szmigiero <mail@maciej.szmigiero.name>
 * Based on w1_therm.c copyright (c) 2004 Evgeniy Polyakov <zbr@ioremap.net>
 */

#include <linux/device.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/mutex.h>
#include <linux/string.h>
#include <linux/types.h>

#include <linux/w1.h>

#define W1_FAMILY_DS2405        0x05

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Maciej S. Szmigiero <mail@maciej.szmigiero.name>");
MODULE_DESCRIPTION("Driver for 1-wire Dallas DS2405 PIO.");
MODULE_ALIAS("w1-family-" __stringify(W1_FAMILY_DS2405));

static int w1_ds2405_select(struct w1_slave *sl, bool only_active)
{
        struct w1_master *dev = sl->master;

        u64 dev_addr = le64_to_cpu(*(u64 *)&sl->reg_num);
        unsigned int bit_ctr;

        if (w1_reset_bus(dev) != 0)
                return 0;

        /*
         * We cannot use a normal Match ROM command
         * since doing so would toggle PIO state
         */
        w1_write_8(dev, only_active ? W1_ALARM_SEARCH : W1_SEARCH);

        for (bit_ctr = 0; bit_ctr < 64; bit_ctr++) {
                int bit2send = !!(dev_addr & BIT(bit_ctr));
                u8 ret;

                ret = w1_triplet(dev, bit2send);

                if ((ret & (BIT(0) | BIT(1))) ==
                    (BIT(0) | BIT(1))) /* no devices found */
                        return 0;

                if (!!(ret & BIT(2)) != bit2send)
                        /* wrong direction taken - no such device */
                        return 0;
        }

        return 1;
}

static int w1_ds2405_read_pio(struct w1_slave *sl)
{
        if (w1_ds2405_select(sl, true))
                return 0; /* "active" means PIO is low */

        if (w1_ds2405_select(sl, false))
                return 1;

        return -ENODEV;
}

static ssize_t state_show(struct device *device,
                          struct device_attribute *attr, char *buf)
{
        struct w1_slave *sl = dev_to_w1_slave(device);
        struct w1_master *dev = sl->master;

        int ret;
        ssize_t f_retval;
        u8 state;

        ret = mutex_lock_interruptible(&dev->bus_mutex);
        if (ret)
                return ret;

        if (!w1_ds2405_select(sl, false)) {
                f_retval = -ENODEV;
                goto out_unlock;
        }

        state = w1_read_8(dev);
        if (state != 0 &&
            state != 0xff) {
                dev_err(device, "non-consistent state %x\n", state);
                f_retval = -EIO;
                goto out_unlock;
        }

        *buf = state ? '1' : '0';
        f_retval = 1;

out_unlock:
        w1_reset_bus(dev);
        mutex_unlock(&dev->bus_mutex);

        return f_retval;
}

static ssize_t output_show(struct device *device,
                           struct device_attribute *attr, char *buf)
{
        struct w1_slave *sl = dev_to_w1_slave(device);
        struct w1_master *dev = sl->master;

        int ret;
        ssize_t f_retval;

        ret = mutex_lock_interruptible(&dev->bus_mutex);
        if (ret)
                return ret;

        ret = w1_ds2405_read_pio(sl);
        if (ret < 0) {
                f_retval = ret;
                goto out_unlock;
        }

        *buf = ret ? '1' : '0';
        f_retval = 1;

out_unlock:
        w1_reset_bus(dev);
        mutex_unlock(&dev->bus_mutex);

        return f_retval;
}

static ssize_t output_store(struct device *device,
                            struct device_attribute *attr,
                            const char *buf, size_t count)
{
        struct w1_slave *sl = dev_to_w1_slave(device);
        struct w1_master *dev = sl->master;

        int ret, current_pio;
        unsigned int val;
        ssize_t f_retval;

        if (count < 1)
                return -EINVAL;

        if (sscanf(buf, " %u%n", &val, &ret) < 1)
                return -EINVAL;

        if (val != 0 && val != 1)
                return -EINVAL;

        f_retval = ret;

        ret = mutex_lock_interruptible(&dev->bus_mutex);
        if (ret)
                return ret;

        current_pio = w1_ds2405_read_pio(sl);
        if (current_pio < 0) {
                f_retval = current_pio;
                goto out_unlock;
        }

        if (current_pio == val)
                goto out_unlock;

        if (w1_reset_bus(dev) != 0) {
                f_retval = -ENODEV;
                goto out_unlock;
        }

        /*
         * can't use w1_reset_select_slave() here since it uses Skip ROM if
         * there is only one device on bus
         */
        do {
                u64 dev_addr = le64_to_cpu(*(u64 *)&sl->reg_num);
                u8 cmd[9];

                cmd[0] = W1_MATCH_ROM;
                memcpy(&cmd[1], &dev_addr, sizeof(dev_addr));

                w1_write_block(dev, cmd, sizeof(cmd));
        } while (0);

out_unlock:
        w1_reset_bus(dev);
        mutex_unlock(&dev->bus_mutex);

        return f_retval;
}

static DEVICE_ATTR_RO(state);
static DEVICE_ATTR_RW(output);

static struct attribute *w1_ds2405_attrs[] = {
        &dev_attr_state.attr,
        &dev_attr_output.attr,
        NULL
};

ATTRIBUTE_GROUPS(w1_ds2405);

static struct w1_family_ops w1_ds2405_fops = {
        .groups = w1_ds2405_groups
};

static struct w1_family w1_family_ds2405 = {
        .fid = W1_FAMILY_DS2405,
        .fops = &w1_ds2405_fops
};

module_w1_family(w1_family_ds2405);