// SPDX-License-Identifier: GPL-2.0-only
/*
 *      w1_ds2408.c - w1 family 29 (DS2408) driver
 *
 * Copyright (c) 2010 Jean-Francois Dagenais <dagenaisj@sonatest.com>
 */

#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/w1.h>

#define W1_FAMILY_DS2408        0x29

#define W1_F29_RETRIES          3

#define W1_F29_REG_LOGIG_STATE             0x88 /* R */
#define W1_F29_REG_OUTPUT_LATCH_STATE      0x89 /* R */
#define W1_F29_REG_ACTIVITY_LATCH_STATE    0x8A /* R */
#define W1_F29_REG_COND_SEARCH_SELECT_MASK 0x8B /* RW */
#define W1_F29_REG_COND_SEARCH_POL_SELECT  0x8C /* RW */
#define W1_F29_REG_CONTROL_AND_STATUS      0x8D /* RW */

#define W1_F29_FUNC_READ_PIO_REGS          0xF0
#define W1_F29_FUNC_CHANN_ACCESS_READ      0xF5
#define W1_F29_FUNC_CHANN_ACCESS_WRITE     0x5A
/* also used to write the control/status reg (0x8D): */
#define W1_F29_FUNC_WRITE_COND_SEARCH_REG  0xCC
#define W1_F29_FUNC_RESET_ACTIVITY_LATCHES 0xC3

#define W1_F29_SUCCESS_CONFIRM_BYTE        0xAA

static int _read_reg(struct w1_slave *sl, u8 address, unsigned char *buf)
{
        u8 wrbuf[3];

        dev_dbg(&sl->dev, "Reading with slave: %p, reg addr: %0#4x, buff addr: %p",
                sl, (unsigned int)address, buf);

        if (!buf)
                return -EINVAL;

        mutex_lock(&sl->master->bus_mutex);
        dev_dbg(&sl->dev, "mutex locked");

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

        wrbuf[0] = W1_F29_FUNC_READ_PIO_REGS;
        wrbuf[1] = address;
        wrbuf[2] = 0;
        w1_write_block(sl->master, wrbuf, 3);
        *buf = w1_read_8(sl->master);

        mutex_unlock(&sl->master->bus_mutex);
        dev_dbg(&sl->dev, "mutex unlocked");
        return 1;
}

static ssize_t state_read(struct file *filp, struct kobject *kobj,
                          const struct bin_attribute *bin_attr, char *buf,
                          loff_t off, size_t count)
{
        dev_dbg(&kobj_to_w1_slave(kobj)->dev,
                "Reading %s kobj: %p, off: %0#10x, count: %zu, buff addr: %p",
                bin_attr->attr.name, kobj, (unsigned int)off, count, buf);
        if (count != 1 || off != 0)
                return -EFAULT;
        return _read_reg(kobj_to_w1_slave(kobj), W1_F29_REG_LOGIG_STATE, buf);
}

static ssize_t output_read(struct file *filp, struct kobject *kobj,
                           const struct bin_attribute *bin_attr, char *buf,
                           loff_t off, size_t count)
{
        dev_dbg(&kobj_to_w1_slave(kobj)->dev,
                "Reading %s kobj: %p, off: %0#10x, count: %zu, buff addr: %p",
                bin_attr->attr.name, kobj, (unsigned int)off, count, buf);
        if (count != 1 || off != 0)
                return -EFAULT;
        return _read_reg(kobj_to_w1_slave(kobj),
                                         W1_F29_REG_OUTPUT_LATCH_STATE, buf);
}

static ssize_t activity_read(struct file *filp, struct kobject *kobj,
                             const struct bin_attribute *bin_attr, char *buf,
                             loff_t off, size_t count)
{
        dev_dbg(&kobj_to_w1_slave(kobj)->dev,
                "Reading %s kobj: %p, off: %0#10x, count: %zu, buff addr: %p",
                bin_attr->attr.name, kobj, (unsigned int)off, count, buf);
        if (count != 1 || off != 0)
                return -EFAULT;
        return _read_reg(kobj_to_w1_slave(kobj),
                                         W1_F29_REG_ACTIVITY_LATCH_STATE, buf);
}

static ssize_t cond_search_mask_read(struct file *filp, struct kobject *kobj,
                                     const struct bin_attribute *bin_attr,
                                     char *buf, loff_t off, size_t count)
{
        dev_dbg(&kobj_to_w1_slave(kobj)->dev,
                "Reading %s kobj: %p, off: %0#10x, count: %zu, buff addr: %p",
                bin_attr->attr.name, kobj, (unsigned int)off, count, buf);
        if (count != 1 || off != 0)
                return -EFAULT;
        return _read_reg(kobj_to_w1_slave(kobj),
                W1_F29_REG_COND_SEARCH_SELECT_MASK, buf);
}

static ssize_t cond_search_polarity_read(struct file *filp,
                                         struct kobject *kobj,
                                         const struct bin_attribute *bin_attr,
                                         char *buf, loff_t off, size_t count)
{
        if (count != 1 || off != 0)
                return -EFAULT;
        return _read_reg(kobj_to_w1_slave(kobj),
                W1_F29_REG_COND_SEARCH_POL_SELECT, buf);
}

static ssize_t status_control_read(struct file *filp, struct kobject *kobj,
                                   const struct bin_attribute *bin_attr,
                                   char *buf, loff_t off, size_t count)
{
        if (count != 1 || off != 0)
                return -EFAULT;
        return _read_reg(kobj_to_w1_slave(kobj),
                W1_F29_REG_CONTROL_AND_STATUS, buf);
}

#ifdef CONFIG_W1_SLAVE_DS2408_READBACK
static bool optional_read_back_valid(struct w1_slave *sl, u8 expected)
{
        u8 w1_buf[3];

        if (w1_reset_resume_command(sl->master))
                return false;

        w1_buf[0] = W1_F29_FUNC_READ_PIO_REGS;
        w1_buf[1] = W1_F29_REG_OUTPUT_LATCH_STATE;
        w1_buf[2] = 0;

        w1_write_block(sl->master, w1_buf, 3);

        return (w1_read_8(sl->master) == expected);
}
#else
static bool optional_read_back_valid(struct w1_slave *sl, u8 expected)
{
        return true;
}
#endif

static ssize_t output_write(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[3];
        unsigned int retries = W1_F29_RETRIES;
        ssize_t bytes_written = -EIO;

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

        dev_dbg(&sl->dev, "locking mutex for write_output");
        mutex_lock(&sl->master->bus_mutex);
        dev_dbg(&sl->dev, "mutex locked");

        if (w1_reset_select_slave(sl))
                goto out;

        do {
                w1_buf[0] = W1_F29_FUNC_CHANN_ACCESS_WRITE;
                w1_buf[1] = *buf;
                w1_buf[2] = ~(*buf);

                w1_write_block(sl->master, w1_buf, 3);

                if (w1_read_8(sl->master) == W1_F29_SUCCESS_CONFIRM_BYTE &&
                    optional_read_back_valid(sl, *buf)) {
                        bytes_written = 1;
                        goto out;
                }

                if (w1_reset_resume_command(sl->master))
                        goto out; /* unrecoverable error */
                /* try again, the slave is ready for a command */
        } while (--retries);

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

        dev_dbg(&sl->dev, "%s, mutex unlocked retries:%d\n",
                (bytes_written > 0) ? "succeeded" : "error", retries);

        return bytes_written;
}


/*
 * Writing to the activity file resets the activity latches.
 */
static ssize_t activity_write(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);
        unsigned int retries = W1_F29_RETRIES;

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

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

        if (w1_reset_select_slave(sl))
                goto error;

        while (retries--) {
                w1_write_8(sl->master, W1_F29_FUNC_RESET_ACTIVITY_LATCHES);
                if (w1_read_8(sl->master) == W1_F29_SUCCESS_CONFIRM_BYTE) {
                        mutex_unlock(&sl->master->bus_mutex);
                        return 1;
                }
                if (w1_reset_resume_command(sl->master))
                        goto error;
        }

error:
        mutex_unlock(&sl->master->bus_mutex);
        return -EIO;
}

static ssize_t status_control_write(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[4];
        unsigned int retries = W1_F29_RETRIES;

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

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

        if (w1_reset_select_slave(sl))
                goto error;

        while (retries--) {
                w1_buf[0] = W1_F29_FUNC_WRITE_COND_SEARCH_REG;
                w1_buf[1] = W1_F29_REG_CONTROL_AND_STATUS;
                w1_buf[2] = 0;
                w1_buf[3] = *buf;

                w1_write_block(sl->master, w1_buf, 4);
                if (w1_reset_resume_command(sl->master))
                        goto error;

                w1_buf[0] = W1_F29_FUNC_READ_PIO_REGS;
                w1_buf[1] = W1_F29_REG_CONTROL_AND_STATUS;
                w1_buf[2] = 0;

                w1_write_block(sl->master, w1_buf, 3);
                if (w1_read_8(sl->master) == *buf) {
                        /* success! */
                        mutex_unlock(&sl->master->bus_mutex);
                        return 1;
                }
        }
error:
        mutex_unlock(&sl->master->bus_mutex);

        return -EIO;
}

/*
 * This is a special sequence we must do to ensure the P0 output is not stuck
 * in test mode. This is described in rev 2 of the ds2408's datasheet
 * (http://datasheets.maximintegrated.com/en/ds/DS2408.pdf) under
 * "APPLICATION INFORMATION/Power-up timing".
 */
static int w1_f29_disable_test_mode(struct w1_slave *sl)
{
        int res;
        u8 magic[10] = {0x96, };
        u64 rn = le64_to_cpu(*((u64 *)&sl->reg_num));

        memcpy(&magic[1], &rn, 8);
        magic[9] = 0x3C;

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

        res = w1_reset_bus(sl->master);
        if (res)
                goto out;
        w1_write_block(sl->master, magic, ARRAY_SIZE(magic));

        res = w1_reset_bus(sl->master);
out:
        mutex_unlock(&sl->master->bus_mutex);
        return res;
}

static const BIN_ATTR_RO(state, 1);
static const BIN_ATTR_RW(output, 1);
static const BIN_ATTR_RW(activity, 1);
static const BIN_ATTR_RO(cond_search_mask, 1);
static const BIN_ATTR_RO(cond_search_polarity, 1);
static const BIN_ATTR_RW(status_control, 1);

static const struct bin_attribute *const w1_f29_bin_attrs[] = {
        &bin_attr_state,
        &bin_attr_output,
        &bin_attr_activity,
        &bin_attr_cond_search_mask,
        &bin_attr_cond_search_polarity,
        &bin_attr_status_control,
        NULL,
};

static const struct attribute_group w1_f29_group = {
        .bin_attrs = w1_f29_bin_attrs,
};

static const struct attribute_group *w1_f29_groups[] = {
        &w1_f29_group,
        NULL,
};

static const struct w1_family_ops w1_f29_fops = {
        .add_slave      = w1_f29_disable_test_mode,
        .groups         = w1_f29_groups,
};

static struct w1_family w1_family_29 = {
        .fid = W1_FAMILY_DS2408,
        .fops = &w1_f29_fops,
};
module_w1_family(w1_family_29);

MODULE_AUTHOR("Jean-Francois Dagenais <dagenaisj@sonatest.com>");
MODULE_DESCRIPTION("w1 family 29 driver for DS2408 8 Pin IO");
MODULE_LICENSE("GPL");
MODULE_ALIAS("w1-family-" __stringify(W1_FAMILY_DS2408));