// SPDX-License-Identifier: GPL-2.0-only
/*
 * w1_ds2406.c - w1 family 12 (DS2406) driver
 * based on w1_ds2413.c by Mariusz Bialonczyk <manio@skyboo.net>
 *
 * Copyright (c) 2014 Scott Alfter <scott@alfter.us>
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/device.h>
#include <linux/types.h>
#include <linux/delay.h>
#include <linux/slab.h>
#include <linux/crc16.h>

#include <linux/w1.h>

#define W1_FAMILY_DS2406        0x12

#define W1_F12_FUNC_READ_STATUS            0xAA
#define W1_F12_FUNC_WRITE_STATUS           0x55

static ssize_t w1_f12_read_state(
        struct file *filp, struct kobject *kobj,
        const struct bin_attribute *bin_attr,
        char *buf, loff_t off, size_t count)
{
        u8 w1_buf[6] = {W1_F12_FUNC_READ_STATUS, 7, 0, 0, 0, 0};
        struct w1_slave *sl = kobj_to_w1_slave(kobj);
        ssize_t rtnval = 1;

        if (off != 0)
                return 0;
        if (!buf)
                return -EINVAL;

        mutex_lock(&sl->master->bus_mutex);

        if (w1_reset_select_slave(sl)) {
                mutex_unlock(&sl->master->bus_mutex);
                return -EIO;
        }

        w1_write_block(sl->master, w1_buf, 3);
        w1_read_block(sl->master, w1_buf+3, 3);
        if (crc16(0, w1_buf, sizeof(w1_buf)) == 0xb001) /* good read? */
                *buf = ((w1_buf[3]>>5)&3)|0x30;
        else
                rtnval = -EIO;

        mutex_unlock(&sl->master->bus_mutex);

        return rtnval;
}

static ssize_t w1_f12_write_output(
        struct file *filp, struct kobject *kobj,
        const struct bin_attribute *bin_attr,
        char *buf, loff_t off, size_t count)
{
        struct w1_slave *sl = kobj_to_w1_slave(kobj);
        u8 w1_buf[6] = {W1_F12_FUNC_WRITE_STATUS, 7, 0, 0, 0, 0};
        ssize_t rtnval = 1;

        if (count != 1 || off != 0)
                return -EFAULT;

        mutex_lock(&sl->master->bus_mutex);

        if (w1_reset_select_slave(sl)) {
                mutex_unlock(&sl->master->bus_mutex);
                return -EIO;
        }

        w1_buf[3] = (((*buf)&3)<<5)|0x1F;
        w1_write_block(sl->master, w1_buf, 4);
        w1_read_block(sl->master, w1_buf+4, 2);
        if (crc16(0, w1_buf, sizeof(w1_buf)) == 0xb001) /* good read? */
                w1_write_8(sl->master, 0xFF);
        else
                rtnval = -EIO;

        mutex_unlock(&sl->master->bus_mutex);
        return rtnval;
}

#define NB_SYSFS_BIN_FILES 2
static const struct bin_attribute w1_f12_sysfs_bin_files[NB_SYSFS_BIN_FILES] = {
        {
                .attr = {
                        .name = "state",
                        .mode = 0444,
                },
                .size = 1,
                .read = w1_f12_read_state,
        },
        {
                .attr = {
                        .name = "output",
                        .mode = 0664,
                },
                .size = 1,
                .write = w1_f12_write_output,
        }
};

static int w1_f12_add_slave(struct w1_slave *sl)
{
        int err = 0;
        int i;

        for (i = 0; i < NB_SYSFS_BIN_FILES && !err; ++i)
                err = sysfs_create_bin_file(
                        &sl->dev.kobj,
                        &(w1_f12_sysfs_bin_files[i]));
        if (err)
                while (--i >= 0)
                        sysfs_remove_bin_file(&sl->dev.kobj,
                                &(w1_f12_sysfs_bin_files[i]));
        return err;
}

static void w1_f12_remove_slave(struct w1_slave *sl)
{
        int i;

        for (i = NB_SYSFS_BIN_FILES - 1; i >= 0; --i)
                sysfs_remove_bin_file(&sl->dev.kobj,
                        &(w1_f12_sysfs_bin_files[i]));
}

static const struct w1_family_ops w1_f12_fops = {
        .add_slave      = w1_f12_add_slave,
        .remove_slave   = w1_f12_remove_slave,
};

static struct w1_family w1_family_12 = {
        .fid = W1_FAMILY_DS2406,
        .fops = &w1_f12_fops,
};
module_w1_family(w1_family_12);

MODULE_AUTHOR("Scott Alfter <scott@alfter.us>");
MODULE_DESCRIPTION("w1 family 12 driver for DS2406 2 Pin IO");
MODULE_LICENSE("GPL");