// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *      ds2490.c  USB to one wire bridge
 *
 * Copyright (c) 2004 Evgeniy Polyakov <zbr@ioremap.net>
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/mod_devicetable.h>
#include <linux/usb.h>
#include <linux/slab.h>

#include <linux/w1.h>

/* USB Standard */
/* USB Control request vendor type */
#define VENDOR                          0x40

/* COMMAND TYPE CODES */
#define CONTROL_CMD                     0x00
#define COMM_CMD                        0x01
#define MODE_CMD                        0x02

/* CONTROL COMMAND CODES */
#define CTL_RESET_DEVICE                0x0000
#define CTL_START_EXE                   0x0001
#define CTL_RESUME_EXE                  0x0002
#define CTL_HALT_EXE_IDLE               0x0003
#define CTL_HALT_EXE_DONE               0x0004
#define CTL_FLUSH_COMM_CMDS             0x0007
#define CTL_FLUSH_RCV_BUFFER            0x0008
#define CTL_FLUSH_XMT_BUFFER            0x0009
#define CTL_GET_COMM_CMDS               0x000A

/* MODE COMMAND CODES */
#define MOD_PULSE_EN                    0x0000
#define MOD_SPEED_CHANGE_EN             0x0001
#define MOD_1WIRE_SPEED                 0x0002
#define MOD_STRONG_PU_DURATION          0x0003
#define MOD_PULLDOWN_SLEWRATE           0x0004
#define MOD_PROG_PULSE_DURATION         0x0005
#define MOD_WRITE1_LOWTIME              0x0006
#define MOD_DSOW0_TREC                  0x0007

/* COMMUNICATION COMMAND CODES */
#define COMM_ERROR_ESCAPE               0x0601
#define COMM_SET_DURATION               0x0012
#define COMM_BIT_IO                     0x0020
#define COMM_PULSE                      0x0030
#define COMM_1_WIRE_RESET               0x0042
#define COMM_BYTE_IO                    0x0052
#define COMM_MATCH_ACCESS               0x0064
#define COMM_BLOCK_IO                   0x0074
#define COMM_READ_STRAIGHT              0x0080
#define COMM_DO_RELEASE                 0x6092
#define COMM_SET_PATH                   0x00A2
#define COMM_WRITE_SRAM_PAGE            0x00B2
#define COMM_WRITE_EPROM                0x00C4
#define COMM_READ_CRC_PROT_PAGE         0x00D4
#define COMM_READ_REDIRECT_PAGE_CRC     0x21E4
#define COMM_SEARCH_ACCESS              0x00F4

/* Communication command bits */
#define COMM_TYPE                       0x0008
#define COMM_SE                         0x0008
#define COMM_D                          0x0008
#define COMM_Z                          0x0008
#define COMM_CH                         0x0008
#define COMM_SM                         0x0008
#define COMM_R                          0x0008
#define COMM_IM                         0x0001

#define COMM_PS                         0x4000
#define COMM_PST                        0x4000
#define COMM_CIB                        0x4000
#define COMM_RTS                        0x4000
#define COMM_DT                         0x2000
#define COMM_SPU                        0x1000
#define COMM_F                          0x0800
#define COMM_NTF                        0x0400
#define COMM_ICP                        0x0200
#define COMM_RST                        0x0100

#define PULSE_PROG                      0x01
#define PULSE_SPUE                      0x02

#define BRANCH_MAIN                     0xCC
#define BRANCH_AUX                      0x33

/* Status flags */
#define ST_SPUA                         0x01  /* Strong Pull-up is active */
#define ST_PRGA                         0x02  /* 12V programming pulse is being generated */
#define ST_12VP                         0x04  /* external 12V programming voltage is present */
#define ST_PMOD                         0x08  /* DS2490 powered from USB and external sources */
#define ST_HALT                         0x10  /* DS2490 is currently halted */
#define ST_IDLE                         0x20  /* DS2490 is currently idle */
#define ST_EPOF                         0x80
/* Status transfer size, 16 bytes status, 16 byte result flags */
#define ST_SIZE                         0x20

/* Result Register flags */
#define RR_DETECT                       0xA5 /* New device detected */
#define RR_NRS                          0x01 /* Reset no presence or ... */
#define RR_SH                           0x02 /* short on reset or set path */
#define RR_APP                          0x04 /* alarming presence on reset */
#define RR_VPP                          0x08 /* 12V expected not seen */
#define RR_CMP                          0x10 /* compare error */
#define RR_CRC                          0x20 /* CRC error detected */
#define RR_RDP                          0x40 /* redirected page */
#define RR_EOS                          0x80 /* end of search error */

#define SPEED_NORMAL                    0x00
#define SPEED_FLEXIBLE                  0x01
#define SPEED_OVERDRIVE                 0x02

#define NUM_EP                          4
#define EP_CONTROL                      0
#define EP_STATUS                       1
#define EP_DATA_OUT                     2
#define EP_DATA_IN                      3

struct ds_device {
        struct list_head        ds_entry;

        struct usb_device       *udev;
        struct usb_interface    *intf;

        int                     ep[NUM_EP];

        /* Strong PullUp
         * 0: pullup not active, else duration in milliseconds
         */
        int                     spu_sleep;
        /* spu_bit contains COMM_SPU or 0 depending on if the strong pullup
         * should be active or not for writes.
         */
        u16                     spu_bit;

        u8                      st_buf[ST_SIZE];
        u8                      byte_buf;

        struct w1_bus_master    master;
};

struct ds_status {
        u8                      enable;
        u8                      speed;
        u8                      pullup_dur;
        u8                      ppuls_dur;
        u8                      pulldown_slew;
        u8                      write1_time;
        u8                      write0_time;
        u8                      reserved0;
        u8                      status;
        u8                      command0;
        u8                      command1;
        u8                      command_buffer_status;
        u8                      data_out_buffer_status;
        u8                      data_in_buffer_status;
        u8                      reserved1;
        u8                      reserved2;
};

static LIST_HEAD(ds_devices);
static DEFINE_MUTEX(ds_mutex);

static int ds_send_control_cmd(struct ds_device *dev, u16 value, u16 index)
{
        int err;

        err = usb_control_msg(dev->udev, usb_sndctrlpipe(dev->udev, dev->ep[EP_CONTROL]),
                        CONTROL_CMD, VENDOR, value, index, NULL, 0, 1000);
        if (err < 0) {
                pr_err("Failed to send command control message %x.%x: err=%d.\n",
                                value, index, err);
                return err;
        }

        return err;
}

static int ds_send_control_mode(struct ds_device *dev, u16 value, u16 index)
{
        int err;

        err = usb_control_msg(dev->udev, usb_sndctrlpipe(dev->udev, dev->ep[EP_CONTROL]),
                        MODE_CMD, VENDOR, value, index, NULL, 0, 1000);
        if (err < 0) {
                pr_err("Failed to send mode control message %x.%x: err=%d.\n",
                                value, index, err);
                return err;
        }

        return err;
}

static int ds_send_control(struct ds_device *dev, u16 value, u16 index)
{
        int err;

        err = usb_control_msg(dev->udev, usb_sndctrlpipe(dev->udev, dev->ep[EP_CONTROL]),
                        COMM_CMD, VENDOR, value, index, NULL, 0, 1000);
        if (err < 0) {
                pr_err("Failed to send control message %x.%x: err=%d.\n",
                                value, index, err);
                return err;
        }

        return err;
}

static inline void ds_print_msg(unsigned char *buf, unsigned char *str, int off)
{
        pr_info("%45s: %8x\n", str, buf[off]);
}

static void ds_dump_status(struct ds_device *dev, unsigned char *buf, int count)
{
        int i;

        pr_info("0x%x: count=%d, status: ", dev->ep[EP_STATUS], count);
        for (i = 0; i < count; ++i)
                pr_info("%02x ", buf[i]);
        pr_info("\n");

        if (count >= 16) {
                ds_print_msg(buf, "enable flag", 0);
                ds_print_msg(buf, "1-wire speed", 1);
                ds_print_msg(buf, "strong pullup duration", 2);
                ds_print_msg(buf, "programming pulse duration", 3);
                ds_print_msg(buf, "pulldown slew rate control", 4);
                ds_print_msg(buf, "write-1 low time", 5);
                ds_print_msg(buf, "data sample offset/write-0 recovery time",
                        6);
                ds_print_msg(buf, "reserved (test register)", 7);
                ds_print_msg(buf, "device status flags", 8);
                ds_print_msg(buf, "communication command byte 1", 9);
                ds_print_msg(buf, "communication command byte 2", 10);
                ds_print_msg(buf, "communication command buffer status", 11);
                ds_print_msg(buf, "1-wire data output buffer status", 12);
                ds_print_msg(buf, "1-wire data input buffer status", 13);
                ds_print_msg(buf, "reserved", 14);
                ds_print_msg(buf, "reserved", 15);
        }
        for (i = 16; i < count; ++i) {
                if (buf[i] == RR_DETECT) {
                        ds_print_msg(buf, "new device detect", i);
                        continue;
                }
                ds_print_msg(buf, "Result Register Value: ", i);
                if (buf[i] & RR_NRS)
                        pr_info("NRS: Reset no presence or ...\n");
                if (buf[i] & RR_SH)
                        pr_info("SH: short on reset or set path\n");
                if (buf[i] & RR_APP)
                        pr_info("APP: alarming presence on reset\n");
                if (buf[i] & RR_VPP)
                        pr_info("VPP: 12V expected not seen\n");
                if (buf[i] & RR_CMP)
                        pr_info("CMP: compare error\n");
                if (buf[i] & RR_CRC)
                        pr_info("CRC: CRC error detected\n");
                if (buf[i] & RR_RDP)
                        pr_info("RDP: redirected page\n");
                if (buf[i] & RR_EOS)
                        pr_info("EOS: end of search error\n");
        }
}

static int ds_recv_status(struct ds_device *dev, struct ds_status *st,
                          bool dump)
{
        int count, err;

        if (st)
                memset(st, 0, sizeof(*st));

        count = 0;
        err = usb_interrupt_msg(dev->udev,
                                usb_rcvintpipe(dev->udev,
                                               dev->ep[EP_STATUS]),
                                dev->st_buf, sizeof(dev->st_buf),
                                &count, 1000);
        if (err < 0) {
                pr_err("Failed to read 1-wire data from 0x%x: err=%d.\n",
                       dev->ep[EP_STATUS], err);
                return err;
        }

        if (dump)
                ds_dump_status(dev, dev->st_buf, count);

        if (st && count >= sizeof(*st))
                memcpy(st, dev->st_buf, sizeof(*st));

        return count;
}

static void ds_reset_device(struct ds_device *dev)
{
        ds_send_control_cmd(dev, CTL_RESET_DEVICE, 0);
        /* Always allow strong pullup which allow individual writes to use
         * the strong pullup.
         */
        if (ds_send_control_mode(dev, MOD_PULSE_EN, PULSE_SPUE))
                pr_err("ds_reset_device: Error allowing strong pullup\n");
        /* Chip strong pullup time was cleared. */
        if (dev->spu_sleep) {
                /* lower 4 bits are 0, see ds_set_pullup */
                u8 del = dev->spu_sleep>>4;
                if (ds_send_control(dev, COMM_SET_DURATION | COMM_IM, del))
                        pr_err("ds_reset_device: Error setting duration\n");
        }
}

static int ds_recv_data(struct ds_device *dev, unsigned char *buf, int size)
{
        int count, err;

        /* Careful on size.  If size is less than what is available in
         * the input buffer, the device fails the bulk transfer and
         * clears the input buffer.  It could read the maximum size of
         * the data buffer, but then do you return the first, last, or
         * some set of the middle size bytes?  As long as the rest of
         * the code is correct there will be size bytes waiting.  A
         * call to ds_wait_status will wait until the device is idle
         * and any data to be received would have been available.
         */
        count = 0;
        err = usb_bulk_msg(dev->udev, usb_rcvbulkpipe(dev->udev, dev->ep[EP_DATA_IN]),
                                buf, size, &count, 1000);
        if (err < 0) {
                pr_info("Clearing ep0x%x.\n", dev->ep[EP_DATA_IN]);
                usb_clear_halt(dev->udev, usb_rcvbulkpipe(dev->udev, dev->ep[EP_DATA_IN]));
                ds_recv_status(dev, NULL, true);
                return err;
        }

#if 0
        {
                int i;

                printk("%s: count=%d: ", __func__, count);
                for (i = 0; i < count; ++i)
                        printk("%02x ", buf[i]);
                printk("\n");
        }
#endif
        return count;
}

static int ds_send_data(struct ds_device *dev, unsigned char *buf, int len)
{
        int count, err;

        count = 0;
        err = usb_bulk_msg(dev->udev, usb_sndbulkpipe(dev->udev, dev->ep[EP_DATA_OUT]), buf, len, &count, 1000);
        if (err < 0) {
                pr_err("Failed to write 1-wire data to ep0x%x: "
                        "err=%d.\n", dev->ep[EP_DATA_OUT], err);
                return err;
        }

        return err;
}

#if 0

int ds_stop_pulse(struct ds_device *dev, int limit)
{
        struct ds_status st;
        int count = 0, err = 0;

        do {
                err = ds_send_control(dev, CTL_HALT_EXE_IDLE, 0);
                if (err)
                        break;
                err = ds_send_control(dev, CTL_RESUME_EXE, 0);
                if (err)
                        break;
                err = ds_recv_status(dev, &st, false);
                if (err)
                        break;

                if ((st.status & ST_SPUA) == 0) {
                        err = ds_send_control_mode(dev, MOD_PULSE_EN, 0);
                        if (err)
                                break;
                }
        } while (++count < limit);

        return err;
}

int ds_detect(struct ds_device *dev, struct ds_status *st)
{
        int err;

        err = ds_send_control_cmd(dev, CTL_RESET_DEVICE, 0);
        if (err)
                return err;

        err = ds_send_control(dev, COMM_SET_DURATION | COMM_IM, 0);
        if (err)
                return err;

        err = ds_send_control(dev, COMM_SET_DURATION | COMM_IM | COMM_TYPE, 0x40);
        if (err)
                return err;

        err = ds_send_control_mode(dev, MOD_PULSE_EN, PULSE_PROG);
        if (err)
                return err;

        err = ds_dump_status(dev, st);

        return err;
}

#endif  /*  0  */

static int ds_wait_status(struct ds_device *dev, struct ds_status *st)
{
        int err, count = 0;

        do {
                st->status = 0;
                err = ds_recv_status(dev, st, false);
#if 0
                if (err >= 0) {
                        int i;
                        printk("0x%x: count=%d, status: ", dev->ep[EP_STATUS], err);
                        for (i = 0; i < err; ++i)
                                printk("%02x ", dev->st_buf[i]);
                        printk("\n");
                }
#endif
        } while (!(st->status & ST_IDLE) && !(err < 0) && ++count < 100);

        if (err >= 16 && st->status & ST_EPOF) {
                pr_info("Resetting device after ST_EPOF.\n");
                ds_reset_device(dev);
                /* Always dump the device status. */
                count = 101;
        }

        /* Dump the status for errors or if there is extended return data.
         * The extended status includes new device detection (maybe someone
         * can do something with it).
         */
        if (err > 16 || count >= 100 || err < 0)
                ds_dump_status(dev, dev->st_buf, err);

        /* Extended data isn't an error.  Well, a short is, but the dump
         * would have already told the user that and we can't do anything
         * about it in software anyway.
         */
        if (count >= 100 || err < 0)
                return -1;
        else
                return 0;
}

static int ds_reset(struct ds_device *dev)
{
        int err;

        /* Other potentionally interesting flags for reset.
         *
         * COMM_NTF: Return result register feedback.  This could be used to
         * detect some conditions such as short, alarming presence, or
         * detect if a new device was detected.
         *
         * COMM_SE which allows SPEED_NORMAL, SPEED_FLEXIBLE, SPEED_OVERDRIVE:
         * Select the data transfer rate.
         */
        err = ds_send_control(dev, COMM_1_WIRE_RESET | COMM_IM, SPEED_NORMAL);
        if (err)
                return err;

        return 0;
}

#if 0
static int ds_set_speed(struct ds_device *dev, int speed)
{
        int err;

        if (speed != SPEED_NORMAL && speed != SPEED_FLEXIBLE && speed != SPEED_OVERDRIVE)
                return -EINVAL;

        if (speed != SPEED_OVERDRIVE)
                speed = SPEED_FLEXIBLE;

        speed &= 0xff;

        err = ds_send_control_mode(dev, MOD_1WIRE_SPEED, speed);
        if (err)
                return err;

        return err;
}
#endif  /*  0  */

static int ds_set_pullup(struct ds_device *dev, int delay)
{
        int err = 0;
        u8 del = 1 + (u8)(delay >> 4);
        /* Just storing delay would not get the trunication and roundup. */
        int ms = del<<4;

        /* Enable spu_bit if a delay is set. */
        dev->spu_bit = delay ? COMM_SPU : 0;
        /* If delay is zero, it has already been disabled, if the time is
         * the same as the hardware was last programmed to, there is also
         * nothing more to do.  Compare with the recalculated value ms
         * rather than del or delay which can have a different value.
         */
        if (delay == 0 || ms == dev->spu_sleep)
                return err;

        err = ds_send_control(dev, COMM_SET_DURATION | COMM_IM, del);
        if (err)
                return err;

        dev->spu_sleep = ms;

        return err;
}

static int ds_touch_bit(struct ds_device *dev, u8 bit, u8 *tbit)
{
        int err;
        struct ds_status st;

        err = ds_send_control(dev, COMM_BIT_IO | COMM_IM | (bit ? COMM_D : 0),
                0);
        if (err)
                return err;

        ds_wait_status(dev, &st);

        err = ds_recv_data(dev, tbit, sizeof(*tbit));
        if (err < 0)
                return err;

        return 0;
}

#if 0
static int ds_write_bit(struct ds_device *dev, u8 bit)
{
        int err;
        struct ds_status st;

        /* Set COMM_ICP to write without a readback.  Note, this will
         * produce one time slot, a down followed by an up with COMM_D
         * only determing the timing.
         */
        err = ds_send_control(dev, COMM_BIT_IO | COMM_IM | COMM_ICP |
                (bit ? COMM_D : 0), 0);
        if (err)
                return err;

        ds_wait_status(dev, &st);

        return 0;
}
#endif

static int ds_write_byte(struct ds_device *dev, u8 byte)
{
        int err;
        struct ds_status st;

        err = ds_send_control(dev, COMM_BYTE_IO | COMM_IM | dev->spu_bit, byte);
        if (err)
                return err;

        if (dev->spu_bit)
                msleep(dev->spu_sleep);

        err = ds_wait_status(dev, &st);
        if (err)
                return err;

        err = ds_recv_data(dev, &dev->byte_buf, 1);
        if (err < 0)
                return err;

        return !(byte == dev->byte_buf);
}

static int ds_read_byte(struct ds_device *dev, u8 *byte)
{
        int err;
        struct ds_status st;

        err = ds_send_control(dev, COMM_BYTE_IO | COMM_IM, 0xff);
        if (err)
                return err;

        ds_wait_status(dev, &st);

        err = ds_recv_data(dev, byte, sizeof(*byte));
        if (err < 0)
                return err;

        return 0;
}

static int ds_read_block(struct ds_device *dev, u8 *buf, int len)
{
        struct ds_status st;
        int err;

        if (len > 64*1024)
                return -E2BIG;

        memset(buf, 0xFF, len);

        err = ds_send_data(dev, buf, len);
        if (err < 0)
                return err;

        err = ds_send_control(dev, COMM_BLOCK_IO | COMM_IM, len);
        if (err)
                return err;

        ds_wait_status(dev, &st);

        memset(buf, 0x00, len);
        err = ds_recv_data(dev, buf, len);

        return err;
}

static int ds_write_block(struct ds_device *dev, u8 *buf, int len)
{
        int err;
        struct ds_status st;

        err = ds_send_data(dev, buf, len);
        if (err < 0)
                return err;

        err = ds_send_control(dev, COMM_BLOCK_IO | COMM_IM | dev->spu_bit, len);
        if (err)
                return err;

        if (dev->spu_bit)
                msleep(dev->spu_sleep);

        ds_wait_status(dev, &st);

        err = ds_recv_data(dev, buf, len);
        if (err < 0)
                return err;

        return !(err == len);
}

static void ds9490r_search(void *data, struct w1_master *master,
        u8 search_type, w1_slave_found_callback callback)
{
        /* When starting with an existing id, the first id returned will
         * be that device (if it is still on the bus most likely).
         *
         * If the number of devices found is less than or equal to the
         * search_limit, that number of IDs will be returned.  If there are
         * more, search_limit IDs will be returned followed by a non-zero
         * discrepency value.
         */
        struct ds_device *dev = data;
        int err;
        u16 value, index;
        struct ds_status st;
        int search_limit;
        int found = 0;
        int i;

        /* DS18b20 spec, 13.16 ms per device, 75 per second, sleep for
         * discovering 8 devices (1 bulk transfer and 1/2 FIFO size) at a time.
         */
        const unsigned long jtime = msecs_to_jiffies(1000*8/75);
        /* FIFO 128 bytes, bulk packet size 64, read a multiple of the
         * packet size.
         */
        const size_t bufsize = 2 * 64;
        u64 *buf, *found_ids;

        buf = kmalloc(bufsize, GFP_KERNEL);
        if (!buf)
                return;

        /*
         * We are holding the bus mutex during the scan, but adding devices via the
         * callback needs the bus to be unlocked. So we queue up found ids here.
         */
        found_ids = kmalloc_array(master->max_slave_count, sizeof(u64), GFP_KERNEL);
        if (!found_ids) {
                kfree(buf);
                return;
        }

        mutex_lock(&master->bus_mutex);

        /* address to start searching at */
        if (ds_send_data(dev, (u8 *)&master->search_id, 8) < 0)
                goto search_out;
        master->search_id = 0;

        value = COMM_SEARCH_ACCESS | COMM_IM | COMM_RST | COMM_SM | COMM_F |
                COMM_RTS;
        search_limit = master->max_slave_count;
        if (search_limit > 255)
                search_limit = 0;
        index = search_type | (search_limit << 8);
        if (ds_send_control(dev, value, index) < 0)
                goto search_out;

        do {
                schedule_timeout(jtime);

                err = ds_recv_status(dev, &st, false);
                if (err < 0 || err < sizeof(st))
                        break;

                if (st.data_in_buffer_status) {
                        /* Bulk in can receive partial ids, but when it does
                         * they fail crc and will be discarded anyway.
                         * That has only been seen when status in buffer
                         * is 0 and bulk is read anyway, so don't read
                         * bulk without first checking if status says there
                         * is data to read.
                         */
                        err = ds_recv_data(dev, (u8 *)buf, bufsize);
                        if (err < 0)
                                break;
                        for (i = 0; i < err/8; ++i) {
                                found_ids[found++] = buf[i];
                                /* can't know if there will be a discrepancy
                                 * value after until the next id */
                                if (found == search_limit) {
                                        master->search_id = buf[i];
                                        break;
                                }
                        }
                }

                if (test_bit(W1_ABORT_SEARCH, &master->flags))
                        break;
        } while (!(st.status & (ST_IDLE | ST_HALT)));

        /* only continue the search if some weren't found */
        if (found <= search_limit) {
                master->search_id = 0;
        } else if (!test_bit(W1_WARN_MAX_COUNT, &master->flags)) {
                /* Only max_slave_count will be scanned in a search,
                 * but it will start where it left off next search
                 * until all ids are identified and then it will start
                 * over.  A continued search will report the previous
                 * last id as the first id (provided it is still on the
                 * bus).
                 */
                dev_info(&dev->udev->dev, "%s: max_slave_count %d reached, "
                        "will continue next search.\n", __func__,
                        master->max_slave_count);
                set_bit(W1_WARN_MAX_COUNT, &master->flags);
        }

search_out:
        mutex_unlock(&master->bus_mutex);
        kfree(buf);

        for (i = 0; i < found; i++) /* run callback for all queued up IDs */
                callback(master, found_ids[i]);
        kfree(found_ids);
}

#if 0
/*
 * FIXME: if this disabled code is ever used in the future all ds_send_data()
 * calls must be changed to use a DMAable buffer.
 */
static int ds_match_access(struct ds_device *dev, u64 init)
{
        int err;
        struct ds_status st;

        err = ds_send_data(dev, (unsigned char *)&init, sizeof(init));
        if (err)
                return err;

        ds_wait_status(dev, &st);

        err = ds_send_control(dev, COMM_MATCH_ACCESS | COMM_IM | COMM_RST, 0x0055);
        if (err)
                return err;

        ds_wait_status(dev, &st);

        return 0;
}

static int ds_set_path(struct ds_device *dev, u64 init)
{
        int err;
        struct ds_status st;
        u8 buf[9];

        memcpy(buf, &init, 8);
        buf[8] = BRANCH_MAIN;

        err = ds_send_data(dev, buf, sizeof(buf));
        if (err)
                return err;

        ds_wait_status(dev, &st);

        err = ds_send_control(dev, COMM_SET_PATH | COMM_IM | COMM_RST, 0);
        if (err)
                return err;

        ds_wait_status(dev, &st);

        return 0;
}

#endif  /*  0  */

static u8 ds9490r_touch_bit(void *data, u8 bit)
{
        struct ds_device *dev = data;

        if (ds_touch_bit(dev, bit, &dev->byte_buf))
                return 0;

        return dev->byte_buf;
}

#if 0
static void ds9490r_write_bit(void *data, u8 bit)
{
        struct ds_device *dev = data;

        ds_write_bit(dev, bit);
}

static u8 ds9490r_read_bit(void *data)
{
        struct ds_device *dev = data;
        int err;

        err = ds_touch_bit(dev, 1, &dev->byte_buf);
        if (err)
                return 0;

        return dev->byte_buf & 1;
}
#endif

static void ds9490r_write_byte(void *data, u8 byte)
{
        struct ds_device *dev = data;

        ds_write_byte(dev, byte);
}

static u8 ds9490r_read_byte(void *data)
{
        struct ds_device *dev = data;
        int err;

        err = ds_read_byte(dev, &dev->byte_buf);
        if (err)
                return 0;

        return dev->byte_buf;
}

static void ds9490r_write_block(void *data, const u8 *buf, int len)
{
        struct ds_device *dev = data;
        u8 *tbuf;

        if (len <= 0)
                return;

        tbuf = kmemdup(buf, len, GFP_KERNEL);
        if (!tbuf)
                return;

        ds_write_block(dev, tbuf, len);

        kfree(tbuf);
}

static u8 ds9490r_read_block(void *data, u8 *buf, int len)
{
        struct ds_device *dev = data;
        int err;
        u8 *tbuf;

        if (len <= 0)
                return 0;

        tbuf = kmalloc(len, GFP_KERNEL);
        if (!tbuf)
                return 0;

        err = ds_read_block(dev, tbuf, len);
        if (err >= 0)
                memcpy(buf, tbuf, len);

        kfree(tbuf);

        return err >= 0 ? len : 0;
}

static u8 ds9490r_reset(void *data)
{
        struct ds_device *dev = data;
        int err;

        err = ds_reset(dev);
        if (err)
                return 1;

        return 0;
}

static u8 ds9490r_set_pullup(void *data, int delay)
{
        struct ds_device *dev = data;

        if (ds_set_pullup(dev, delay))
                return 1;

        return 0;
}

static int ds_w1_init(struct ds_device *dev)
{
        memset(&dev->master, 0, sizeof(struct w1_bus_master));

        /* Reset the device as it can be in a bad state.
         * This is necessary because a block write will wait for data
         * to be placed in the output buffer and block any later
         * commands which will keep accumulating and the device will
         * not be idle.  Another case is removing the ds2490 module
         * while a bus search is in progress, somehow a few commands
         * get through, but the input transfers fail leaving data in
         * the input buffer.  This will cause the next read to fail
         * see the note in ds_recv_data.
         */
        ds_reset_device(dev);

        dev->master.data        = dev;
        dev->master.touch_bit   = &ds9490r_touch_bit;
        /* read_bit and write_bit in w1_bus_master are expected to set and
         * sample the line level.  For write_bit that means it is expected to
         * set it to that value and leave it there.  ds2490 only supports an
         * individual time slot at the lowest level.  The requirement from
         * pulling the bus state down to reading the state is 15us, something
         * that isn't realistic on the USB bus anyway.
        dev->master.read_bit    = &ds9490r_read_bit;
        dev->master.write_bit   = &ds9490r_write_bit;
        */
        dev->master.read_byte   = &ds9490r_read_byte;
        dev->master.write_byte  = &ds9490r_write_byte;
        dev->master.read_block  = &ds9490r_read_block;
        dev->master.write_block = &ds9490r_write_block;
        dev->master.reset_bus   = &ds9490r_reset;
        dev->master.set_pullup  = &ds9490r_set_pullup;
        dev->master.search      = &ds9490r_search;

        return w1_add_master_device(&dev->master);
}

static void ds_w1_fini(struct ds_device *dev)
{
        w1_remove_master_device(&dev->master);
}

static int ds_probe(struct usb_interface *intf,
                    const struct usb_device_id *udev_id)
{
        struct usb_device *udev = interface_to_usbdev(intf);
        struct usb_endpoint_descriptor *endpoint;
        struct usb_host_interface *iface_desc;
        struct ds_device *dev;
        int i, err, alt;

        dev = kzalloc(sizeof(struct ds_device), GFP_KERNEL);
        if (!dev) {
                pr_info("Failed to allocate new DS9490R structure.\n");
                return -ENOMEM;
        }

        dev->udev = usb_get_dev(udev);
        if (!dev->udev) {
                err = -ENOMEM;
                goto err_out_free;
        }
        memset(dev->ep, 0, sizeof(dev->ep));

        usb_set_intfdata(intf, dev);

        err = usb_reset_configuration(dev->udev);
        if (err) {
                dev_err(&dev->udev->dev,
                        "Failed to reset configuration: err=%d.\n", err);
                goto err_out_clear;
        }

        /* alternative 3, 1ms interrupt (greatly speeds search), 64 byte bulk */
        alt = 3;
        err = usb_set_interface(dev->udev,
                intf->cur_altsetting->desc.bInterfaceNumber, alt);
        if (err) {
                dev_err(&dev->udev->dev, "Failed to set alternative setting %d "
                        "for %d interface: err=%d.\n", alt,
                        intf->cur_altsetting->desc.bInterfaceNumber, err);
                goto err_out_clear;
        }

        iface_desc = intf->cur_altsetting;
        if (iface_desc->desc.bNumEndpoints != NUM_EP-1) {
                pr_info("Num endpoints=%d. It is not DS9490R.\n",
                        iface_desc->desc.bNumEndpoints);
                err = -EINVAL;
                goto err_out_clear;
        }

        /*
         * This loop doesn'd show control 0 endpoint,
         * so we will fill only 1-3 endpoints entry.
         */
        for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) {
                endpoint = &iface_desc->endpoint[i].desc;

                dev->ep[i+1] = endpoint->bEndpointAddress;
#if 0
                printk("%d: addr=%x, size=%d, dir=%s, type=%x\n",
                        i, endpoint->bEndpointAddress, le16_to_cpu(endpoint->wMaxPacketSize),
                        (endpoint->bEndpointAddress & USB_DIR_IN)?"IN":"OUT",
                        endpoint->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK);
#endif
        }

        err = ds_w1_init(dev);
        if (err)
                goto err_out_clear;

        mutex_lock(&ds_mutex);
        list_add_tail(&dev->ds_entry, &ds_devices);
        mutex_unlock(&ds_mutex);

        return 0;

err_out_clear:
        usb_set_intfdata(intf, NULL);
        usb_put_dev(dev->udev);
err_out_free:
        kfree(dev);
        return err;
}

static void ds_disconnect(struct usb_interface *intf)
{
        struct ds_device *dev;

        dev = usb_get_intfdata(intf);
        if (!dev)
                return;

        mutex_lock(&ds_mutex);
        list_del(&dev->ds_entry);
        mutex_unlock(&ds_mutex);

        ds_w1_fini(dev);

        usb_set_intfdata(intf, NULL);

        usb_put_dev(dev->udev);
        kfree(dev);
}

static const struct usb_device_id ds_id_table[] = {
        { USB_DEVICE(0x04fa, 0x2490) },
        { },
};
MODULE_DEVICE_TABLE(usb, ds_id_table);

static struct usb_driver ds_driver = {
        .name =         "DS9490R",
        .probe =        ds_probe,
        .disconnect =   ds_disconnect,
        .id_table =     ds_id_table,
};
module_usb_driver(ds_driver);

MODULE_AUTHOR("Evgeniy Polyakov <zbr@ioremap.net>");
MODULE_DESCRIPTION("DS2490 USB <-> W1 bus master driver (DS9490*)");
MODULE_LICENSE("GPL");