/*
 * comedi/drivers/dt9812.c
 *   COMEDI driver for DataTranslation DT9812 USB module
 *
 * Copyright (C) 2005 Anders Blomdell <anders.blomdell@control.lth.se>
 *
 * COMEDI - Linux Control and Measurement Device Interface
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.

 *  This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 */

/*
Driver: dt9812
Description: Data Translation DT9812 USB module
Author: anders.blomdell@control.lth.se (Anders Blomdell)
Status: in development
Devices: [Data Translation] DT9812 (dt9812)
Updated: Sun Nov 20 20:18:34 EST 2005

This driver works, but bulk transfers not implemented. Might be a starting point
for someone else. I found out too late that USB has too high latencies (>1 ms)
for my needs.
*/

/*
 * Nota Bene:
 *   1. All writes to command pipe has to be 32 bytes (ISP1181B SHRTP=0 ?)
 *   2. The DDK source (as of sep 2005) is in error regarding the
 *      input MUX bits (example code says P4, but firmware schematics
 *      says P1).
 */

#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/kref.h>
#include <linux/uaccess.h>
#include <linux/usb.h>

#include "../comedidev.h"

#define DT9812_DIAGS_BOARD_INFO_ADDR    0xFBFF
#define DT9812_MAX_WRITE_CMD_PIPE_SIZE  32
#define DT9812_MAX_READ_CMD_PIPE_SIZE   32

/*
 * See Silican Laboratories C8051F020/1/2/3 manual
 */
#define F020_SFR_P4                     0x84
#define F020_SFR_P1                     0x90
#define F020_SFR_P2                     0xa0
#define F020_SFR_P3                     0xb0
#define F020_SFR_AMX0CF                 0xba
#define F020_SFR_AMX0SL                 0xbb
#define F020_SFR_ADC0CF                 0xbc
#define F020_SFR_ADC0L                  0xbe
#define F020_SFR_ADC0H                  0xbf
#define F020_SFR_DAC0L                  0xd2
#define F020_SFR_DAC0H                  0xd3
#define F020_SFR_DAC0CN                 0xd4
#define F020_SFR_DAC1L                  0xd5
#define F020_SFR_DAC1H                  0xd6
#define F020_SFR_DAC1CN                 0xd7
#define F020_SFR_ADC0CN                 0xe8

#define F020_MASK_ADC0CF_AMP0GN0        0x01
#define F020_MASK_ADC0CF_AMP0GN1        0x02
#define F020_MASK_ADC0CF_AMP0GN2        0x04

#define F020_MASK_ADC0CN_AD0EN          0x80
#define F020_MASK_ADC0CN_AD0INT         0x20
#define F020_MASK_ADC0CN_AD0BUSY        0x10

#define F020_MASK_DACxCN_DACxEN         0x80

enum {
        /* A/D  D/A  DI  DO  CT */
        DT9812_DEVID_DT9812_10, /*  8    2   8   8   1  +/- 10V */
        DT9812_DEVID_DT9812_2PT5,       /* 8    2   8   8   1  0-2.44V */
#if 0
        DT9812_DEVID_DT9813,    /*  16   2   4   4   1  +/- 10V */
        DT9812_DEVID_DT9814     /*  24   2   0   0   1  +/- 10V */
#endif
};

enum dt9812_gain {
        DT9812_GAIN_0PT25 = 1,
        DT9812_GAIN_0PT5 = 2,
        DT9812_GAIN_1 = 4,
        DT9812_GAIN_2 = 8,
        DT9812_GAIN_4 = 16,
        DT9812_GAIN_8 = 32,
        DT9812_GAIN_16 = 64,
};

enum {
        DT9812_LEAST_USB_FIRMWARE_CMD_CODE = 0,
        /* Write Flash memory */
        DT9812_W_FLASH_DATA = 0,
        /* Read Flash memory misc config info */
        DT9812_R_FLASH_DATA = 1,

        /*
         * Register read/write commands for processor
         */

        /* Read a single byte of USB memory */
        DT9812_R_SINGLE_BYTE_REG = 2,
        /* Write a single byte of USB memory */
        DT9812_W_SINGLE_BYTE_REG = 3,
        /* Multiple Reads of USB memory */
        DT9812_R_MULTI_BYTE_REG = 4,
        /* Multiple Writes of USB memory */
        DT9812_W_MULTI_BYTE_REG = 5,
        /* Read, (AND) with mask, OR value, then write (single) */
        DT9812_RMW_SINGLE_BYTE_REG = 6,
        /* Read, (AND) with mask, OR value, then write (multiple) */
        DT9812_RMW_MULTI_BYTE_REG = 7,

        /*
         * Register read/write commands for SMBus
         */

        /* Read a single byte of SMBus */
        DT9812_R_SINGLE_BYTE_SMBUS = 8,
        /* Write a single byte of SMBus */
        DT9812_W_SINGLE_BYTE_SMBUS = 9,
        /* Multiple Reads of SMBus */
        DT9812_R_MULTI_BYTE_SMBUS = 10,
        /* Multiple Writes of SMBus */
        DT9812_W_MULTI_BYTE_SMBUS = 11,

        /*
         * Register read/write commands for a device
         */

        /* Read a single byte of a device */
        DT9812_R_SINGLE_BYTE_DEV = 12,
        /* Write a single byte of a device */
        DT9812_W_SINGLE_BYTE_DEV = 13,
        /* Multiple Reads of a device */
        DT9812_R_MULTI_BYTE_DEV = 14,
        /* Multiple Writes of a device */
        DT9812_W_MULTI_BYTE_DEV = 15,

        /* Not sure if we'll need this */
        DT9812_W_DAC_THRESHOLD = 16,

        /* Set interrupt on change mask */
        DT9812_W_INT_ON_CHANGE_MASK = 17,

        /* Write (or Clear) the CGL for the ADC */
        DT9812_W_CGL = 18,
        /* Multiple Reads of USB memory */
        DT9812_R_MULTI_BYTE_USBMEM = 19,
        /* Multiple Writes to USB memory */
        DT9812_W_MULTI_BYTE_USBMEM = 20,

        /* Issue a start command to a given subsystem */
        DT9812_START_SUBSYSTEM = 21,
        /* Issue a stop command to a given subsystem */
        DT9812_STOP_SUBSYSTEM = 22,

        /* calibrate the board using CAL_POT_CMD */
        DT9812_CALIBRATE_POT = 23,
        /* set the DAC FIFO size */
        DT9812_W_DAC_FIFO_SIZE = 24,
        /* Write or Clear the CGL for the DAC */
        DT9812_W_CGL_DAC = 25,
        /* Read a single value from a subsystem */
        DT9812_R_SINGLE_VALUE_CMD = 26,
        /* Write a single value to a subsystem */
        DT9812_W_SINGLE_VALUE_CMD = 27,
        /* Valid DT9812_USB_FIRMWARE_CMD_CODE's will be less than this number */
        DT9812_MAX_USB_FIRMWARE_CMD_CODE,
};

struct dt9812_flash_data {
        u16 numbytes;
        u16 address;
};

#define DT9812_MAX_NUM_MULTI_BYTE_RDS  \
    ((DT9812_MAX_WRITE_CMD_PIPE_SIZE - 4 - 1) / sizeof(u8))

struct dt9812_read_multi {
        u8 count;
        u8 address[DT9812_MAX_NUM_MULTI_BYTE_RDS];
};

struct dt9812_write_byte {
        u8 address;
        u8 value;
};

#define DT9812_MAX_NUM_MULTI_BYTE_WRTS  \
    ((DT9812_MAX_WRITE_CMD_PIPE_SIZE - 4 - 1) / \
      sizeof(struct dt9812_write_byte))

struct dt9812_write_multi {
        u8 count;
        struct dt9812_write_byte write[DT9812_MAX_NUM_MULTI_BYTE_WRTS];
};

struct dt9812_rmw_byte {
        u8 address;
        u8 and_mask;
        u8 or_value;
};

#define DT9812_MAX_NUM_MULTI_BYTE_RMWS  \
    ((DT9812_MAX_WRITE_CMD_PIPE_SIZE - 4 - 1) / sizeof(struct dt9812_rmw_byte))

struct dt9812_rmw_multi {
        u8 count;
        struct dt9812_rmw_byte rmw[DT9812_MAX_NUM_MULTI_BYTE_RMWS];
};

struct dt9812_usb_cmd {
        u32 cmd;
        union {
                struct dt9812_flash_data flash_data_info;
                struct dt9812_read_multi read_multi_info;
                struct dt9812_write_multi write_multi_info;
                struct dt9812_rmw_multi rmw_multi_info;
        } u;
#if 0
        WRITE_BYTE_INFO WriteByteInfo;
        READ_BYTE_INFO ReadByteInfo;
        WRITE_MULTI_INFO WriteMultiInfo;
        READ_MULTI_INFO ReadMultiInfo;
        RMW_BYTE_INFO RMWByteInfo;
        RMW_MULTI_INFO RMWMultiInfo;
        DAC_THRESHOLD_INFO DacThresholdInfo;
        INT_ON_CHANGE_MASK_INFO IntOnChangeMaskInfo;
        CGL_INFO CglInfo;
        SUBSYSTEM_INFO SubsystemInfo;
        CAL_POT_CMD CalPotCmd;
        WRITE_DEV_BYTE_INFO WriteDevByteInfo;
        READ_DEV_BYTE_INFO ReadDevByteInfo;
        WRITE_DEV_MULTI_INFO WriteDevMultiInfo;
        READ_DEV_MULTI_INFO ReadDevMultiInfo;
        READ_SINGLE_VALUE_INFO ReadSingleValueInfo;
        WRITE_SINGLE_VALUE_INFO WriteSingleValueInfo;
#endif
};

#define DT9812_NUM_SLOTS        16

static DECLARE_MUTEX(dt9812_mutex);

static struct usb_device_id dt9812_table[] = {
        {USB_DEVICE(0x0867, 0x9812)},
        {}                      /* Terminating entry */
};

MODULE_DEVICE_TABLE(usb, dt9812_table);

struct usb_dt9812 {
        struct slot_dt9812 *slot;
        struct usb_device *udev;
        struct usb_interface *interface;
        u16 vendor;
        u16 product;
        u16 device;
        u32 serial;
        struct {
                __u8 addr;
                size_t size;
        } message_pipe, command_write, command_read, write_stream, read_stream;
        struct kref kref;
        u16 analog_out_shadow[2];
        u8 digital_out_shadow;
};

struct comedi_dt9812 {
        struct slot_dt9812 *slot;
        u32 serial;
};

struct slot_dt9812 {
        struct semaphore mutex;
        u32 serial;
        struct usb_dt9812 *usb;
        struct comedi_dt9812 *comedi;
};

static const struct comedi_lrange dt9812_10_ain_range = { 1, {
                                                              BIP_RANGE(10),
                                                              }
};

static const struct comedi_lrange dt9812_2pt5_ain_range = { 1, {
                                                                UNI_RANGE(2.5),
                                                                }
};

static const struct comedi_lrange dt9812_10_aout_range = { 1, {
                                                               BIP_RANGE(10),
                                                               }
};

static const struct comedi_lrange dt9812_2pt5_aout_range = { 1, {
                                                                 UNI_RANGE(2.5),
                                                                 }
};

static struct slot_dt9812 dt9812[DT9812_NUM_SLOTS];

/* Useful shorthand access to private data */
#define devpriv ((struct comedi_dt9812 *)dev->private)

static inline struct usb_dt9812 *to_dt9812_dev(struct kref *d)
{
        return container_of(d, struct usb_dt9812, kref);
}

static void dt9812_delete(struct kref *kref)
{
        struct usb_dt9812 *dev = to_dt9812_dev(kref);

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

static int dt9812_read_info(struct usb_dt9812 *dev, int offset, void *buf,
                            size_t buf_size)
{
        struct dt9812_usb_cmd cmd;
        int count, retval;

        cmd.cmd = cpu_to_le32(DT9812_R_FLASH_DATA);
        cmd.u.flash_data_info.address =
            cpu_to_le16(DT9812_DIAGS_BOARD_INFO_ADDR + offset);
        cmd.u.flash_data_info.numbytes = cpu_to_le16(buf_size);

        /* DT9812 only responds to 32 byte writes!! */
        count = 32;
        retval = usb_bulk_msg(dev->udev,
                              usb_sndbulkpipe(dev->udev,
                                              dev->command_write.addr),
                              &cmd, 32, &count, HZ * 1);
        if (retval)
                return retval;
        retval = usb_bulk_msg(dev->udev,
                              usb_rcvbulkpipe(dev->udev,
                                              dev->command_read.addr),
                              buf, buf_size, &count, HZ * 1);
        return retval;
}

static int dt9812_read_multiple_registers(struct usb_dt9812 *dev, int reg_count,
                                          u8 * address, u8 * value)
{
        struct dt9812_usb_cmd cmd;
        int i, count, retval;

        cmd.cmd = cpu_to_le32(DT9812_R_MULTI_BYTE_REG);
        cmd.u.read_multi_info.count = reg_count;
        for (i = 0; i < reg_count; i++)
                cmd.u.read_multi_info.address[i] = address[i];

        /* DT9812 only responds to 32 byte writes!! */
        count = 32;
        retval = usb_bulk_msg(dev->udev,
                              usb_sndbulkpipe(dev->udev,
                                              dev->command_write.addr),
                              &cmd, 32, &count, HZ * 1);
        if (retval)
                return retval;
        retval = usb_bulk_msg(dev->udev,
                              usb_rcvbulkpipe(dev->udev,
                                              dev->command_read.addr),
                              value, reg_count, &count, HZ * 1);
        return retval;
}

static int dt9812_write_multiple_registers(struct usb_dt9812 *dev,
                                           int reg_count, u8 * address,
                                           u8 * value)
{
        struct dt9812_usb_cmd cmd;
        int i, count, retval;

        cmd.cmd = cpu_to_le32(DT9812_W_MULTI_BYTE_REG);
        cmd.u.read_multi_info.count = reg_count;
        for (i = 0; i < reg_count; i++) {
                cmd.u.write_multi_info.write[i].address = address[i];
                cmd.u.write_multi_info.write[i].value = value[i];
        }
        /* DT9812 only responds to 32 byte writes!! */
        retval = usb_bulk_msg(dev->udev,
                              usb_sndbulkpipe(dev->udev,
                                              dev->command_write.addr),
                              &cmd, 32, &count, HZ * 1);
        return retval;
}

static int dt9812_rmw_multiple_registers(struct usb_dt9812 *dev, int reg_count,
                                         struct dt9812_rmw_byte *rmw)
{
        struct dt9812_usb_cmd cmd;
        int i, count, retval;

        cmd.cmd = cpu_to_le32(DT9812_RMW_MULTI_BYTE_REG);
        cmd.u.rmw_multi_info.count = reg_count;
        for (i = 0; i < reg_count; i++)
                cmd.u.rmw_multi_info.rmw[i] = rmw[i];

        /* DT9812 only responds to 32 byte writes!! */
        retval = usb_bulk_msg(dev->udev,
                              usb_sndbulkpipe(dev->udev,
                                              dev->command_write.addr),
                              &cmd, 32, &count, HZ * 1);
        return retval;
}

static int dt9812_digital_in(struct slot_dt9812 *slot, u8 * bits)
{
        int result = -ENODEV;

        down(&slot->mutex);
        if (slot->usb) {
                u8 reg[2] = { F020_SFR_P3, F020_SFR_P1 };
                u8 value[2];

                result = dt9812_read_multiple_registers(slot->usb, 2, reg,
                                                        value);
                if (result == 0) {
                        /*
                         * bits 0-6 in F020_SFR_P3 are bits 0-6 in the digital
                         * input port bit 3 in F020_SFR_P1 is bit 7 in the
                         * digital input port
                         */
                        *bits = (value[0] & 0x7f) | ((value[1] & 0x08) << 4);
                        /* printk("%2.2x, %2.2x -> %2.2x\n",
                           value[0], value[1], *bits); */
                }
        }
        up(&slot->mutex);

        return result;
}

static int dt9812_digital_out(struct slot_dt9812 *slot, u8 bits)
{
        int result = -ENODEV;

        down(&slot->mutex);
        if (slot->usb) {
                u8 reg[1];
                u8 value[1];

                reg[0] = F020_SFR_P2;
                value[0] = bits;
                result = dt9812_write_multiple_registers(slot->usb, 1, reg,
                                                         value);
                slot->usb->digital_out_shadow = bits;
        }
        up(&slot->mutex);
        return result;
}

static int dt9812_digital_out_shadow(struct slot_dt9812 *slot, u8 * bits)
{
        int result = -ENODEV;

        down(&slot->mutex);
        if (slot->usb) {
                *bits = slot->usb->digital_out_shadow;
                result = 0;
        }
        up(&slot->mutex);
        return result;
}

static void dt9812_configure_mux(struct usb_dt9812 *dev,
                                 struct dt9812_rmw_byte *rmw, int channel)
{
        if (dev->device == DT9812_DEVID_DT9812_10) {
                /* In the DT9812/10V MUX is selected by P1.5-7 */
                rmw->address = F020_SFR_P1;
                rmw->and_mask = 0xe0;
                rmw->or_value = channel << 5;
        } else {
                /* In the DT9812/2.5V, internal mux is selected by bits 0:2 */
                rmw->address = F020_SFR_AMX0SL;
                rmw->and_mask = 0xff;
                rmw->or_value = channel & 0x07;
        }
}

static void dt9812_configure_gain(struct usb_dt9812 *dev,
                                  struct dt9812_rmw_byte *rmw,
                                  enum dt9812_gain gain)
{
        if (dev->device == DT9812_DEVID_DT9812_10) {
                /* In the DT9812/10V, there is an external gain of 0.5 */
                gain <<= 1;
        }

        rmw->address = F020_SFR_ADC0CF;
        rmw->and_mask = F020_MASK_ADC0CF_AMP0GN2 |
            F020_MASK_ADC0CF_AMP0GN1 | F020_MASK_ADC0CF_AMP0GN0;
        switch (gain) {
                /*
                 * 000 -> Gain =  1
                 * 001 -> Gain =  2
                 * 010 -> Gain =  4
                 * 011 -> Gain =  8
                 * 10x -> Gain = 16
                 * 11x -> Gain =  0.5
                 */
        case DT9812_GAIN_0PT5:
                rmw->or_value = F020_MASK_ADC0CF_AMP0GN2 ||
                    F020_MASK_ADC0CF_AMP0GN1;
                break;
        case DT9812_GAIN_1:
                rmw->or_value = 0x00;
                break;
        case DT9812_GAIN_2:
                rmw->or_value = F020_MASK_ADC0CF_AMP0GN0;
                break;
        case DT9812_GAIN_4:
                rmw->or_value = F020_MASK_ADC0CF_AMP0GN1;
                break;
        case DT9812_GAIN_8:
                rmw->or_value = F020_MASK_ADC0CF_AMP0GN1 ||
                    F020_MASK_ADC0CF_AMP0GN0;
                break;
        case DT9812_GAIN_16:
                rmw->or_value = F020_MASK_ADC0CF_AMP0GN2;
                break;
        default:
                err("Illegal gain %d\n", gain);

        }
}

static int dt9812_analog_in(struct slot_dt9812 *slot, int channel, u16 * value,
                            enum dt9812_gain gain)
{
        struct dt9812_rmw_byte rmw[3];
        u8 reg[3] = {
                F020_SFR_ADC0CN,
                F020_SFR_ADC0H,
                F020_SFR_ADC0L
        };
        u8 val[3];
        int result = -ENODEV;

        down(&slot->mutex);
        if (!slot->usb)
                goto exit;

        /* 1 select the gain */
        dt9812_configure_gain(slot->usb, &rmw[0], gain);

        /* 2 set the MUX to select the channel */
        dt9812_configure_mux(slot->usb, &rmw[1], channel);

        /* 3 start conversion */
        rmw[2].address = F020_SFR_ADC0CN;
        rmw[2].and_mask = 0xff;
        rmw[2].or_value = F020_MASK_ADC0CN_AD0EN | F020_MASK_ADC0CN_AD0BUSY;

        result = dt9812_rmw_multiple_registers(slot->usb, 3, rmw);
        if (result)
                goto exit;

        /* read the status and ADC */
        result = dt9812_read_multiple_registers(slot->usb, 3, reg, val);
        if (result)
                goto exit;
        /*
         * An ADC conversion takes 16 SAR clocks cycles, i.e. about 9us.
         * Therefore, between the instant that AD0BUSY was set via
         * dt9812_rmw_multiple_registers and the read of AD0BUSY via
         * dt9812_read_multiple_registers, the conversion should be complete
         * since these two operations require two USB transactions each taking
         * at least a millisecond to complete.  However, lets make sure that
         * conversion is finished.
         */
        if ((val[0] & (F020_MASK_ADC0CN_AD0INT | F020_MASK_ADC0CN_AD0BUSY)) ==
            F020_MASK_ADC0CN_AD0INT) {
                switch (slot->usb->device) {
                case DT9812_DEVID_DT9812_10:
                        /*
                         * For DT9812-10V the personality module set the
                         * encoding to 2's complement. Hence, convert it before
                         * returning it
                         */
                        *value = ((val[1] << 8) | val[2]) + 0x800;
                        break;
                case DT9812_DEVID_DT9812_2PT5:
                        *value = (val[1] << 8) | val[2];
                        break;
                }
        }

exit:
        up(&slot->mutex);
        return result;
}

static int dt9812_analog_out_shadow(struct slot_dt9812 *slot, int channel,
                                    u16 * value)
{
        int result = -ENODEV;

        down(&slot->mutex);
        if (slot->usb) {
                *value = slot->usb->analog_out_shadow[channel];
                result = 0;
        }
        up(&slot->mutex);

        return result;
}

static int dt9812_analog_out(struct slot_dt9812 *slot, int channel, u16 value)
{
        int result = -ENODEV;

        down(&slot->mutex);
        if (slot->usb) {
                struct dt9812_rmw_byte rmw[3];

                switch (channel) {
                case 0:
                        /* 1. Set DAC mode */
                        rmw[0].address = F020_SFR_DAC0CN;
                        rmw[0].and_mask = 0xff;
                        rmw[0].or_value = F020_MASK_DACxCN_DACxEN;

                        /* 2 load low byte of DAC value first */
                        rmw[1].address = F020_SFR_DAC0L;
                        rmw[1].and_mask = 0xff;
                        rmw[1].or_value = value & 0xff;

                        /* 3 load high byte of DAC value next to latch the
                           12-bit value */
                        rmw[2].address = F020_SFR_DAC0H;
                        rmw[2].and_mask = 0xff;
                        rmw[2].or_value = (value >> 8) & 0xf;
                        break;

                case 1:
                        /* 1. Set DAC mode */
                        rmw[0].address = F020_SFR_DAC1CN;
                        rmw[0].and_mask = 0xff;
                        rmw[0].or_value = F020_MASK_DACxCN_DACxEN;

                        /* 2 load low byte of DAC value first */
                        rmw[1].address = F020_SFR_DAC1L;
                        rmw[1].and_mask = 0xff;
                        rmw[1].or_value = value & 0xff;

                        /* 3 load high byte of DAC value next to latch the
                           12-bit value */
                        rmw[2].address = F020_SFR_DAC1H;
                        rmw[2].and_mask = 0xff;
                        rmw[2].or_value = (value >> 8) & 0xf;
                        break;
                }
                result = dt9812_rmw_multiple_registers(slot->usb, 3, rmw);
                slot->usb->analog_out_shadow[channel] = value;
        }
        up(&slot->mutex);

        return result;
}

/*
 * USB framework functions
 */

static int dt9812_probe(struct usb_interface *interface,
                        const struct usb_device_id *id)
{
        int retval = -ENOMEM;
        struct usb_dt9812 *dev = NULL;
        struct usb_host_interface *iface_desc;
        struct usb_endpoint_descriptor *endpoint;
        int i;
        u8 fw;

        /* allocate memory for our device state and initialize it */
        dev = kzalloc(sizeof(*dev), GFP_KERNEL);
        if (dev == NULL) {
                dev_err(&interface->dev, "Out of memory\n");
                goto error;
        }
        kref_init(&dev->kref);

        dev->udev = usb_get_dev(interface_to_usbdev(interface));
        dev->interface = interface;

        /* Check endpoints */
        iface_desc = interface->cur_altsetting;

        if (iface_desc->desc.bNumEndpoints != 5) {
                err("Wrong number of endpints.");
                retval = -ENODEV;
                goto error;
        }

        for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) {
                int direction = -1;
                endpoint = &iface_desc->endpoint[i].desc;
                switch (i) {
                case 0:
                        direction = USB_DIR_IN;
                        dev->message_pipe.addr = endpoint->bEndpointAddress;
                        dev->message_pipe.size =
                            le16_to_cpu(endpoint->wMaxPacketSize);

                        break;
                case 1:
                        direction = USB_DIR_OUT;
                        dev->command_write.addr = endpoint->bEndpointAddress;
                        dev->command_write.size =
                            le16_to_cpu(endpoint->wMaxPacketSize);
                        break;
                case 2:
                        direction = USB_DIR_IN;
                        dev->command_read.addr = endpoint->bEndpointAddress;
                        dev->command_read.size =
                            le16_to_cpu(endpoint->wMaxPacketSize);
                        break;
                case 3:
                        direction = USB_DIR_OUT;
                        dev->write_stream.addr = endpoint->bEndpointAddress;
                        dev->write_stream.size =
                            le16_to_cpu(endpoint->wMaxPacketSize);
                        break;
                case 4:
                        direction = USB_DIR_IN;
                        dev->read_stream.addr = endpoint->bEndpointAddress;
                        dev->read_stream.size =
                            le16_to_cpu(endpoint->wMaxPacketSize);
                        break;
                }
                if ((endpoint->bEndpointAddress & USB_DIR_IN) != direction) {
                        dev_err(&interface->dev,
                                "Endpoint has wrong direction.\n");
                        retval = -ENODEV;
                        goto error;
                }
        }
        if (dt9812_read_info(dev, 0, &fw, sizeof(fw)) != 0) {
                /*
                 * Seems like a configuration reset is necessary if driver is
                 * reloaded while device is attached
                 */
                usb_reset_configuration(dev->udev);
                for (i = 0; i < 10; i++) {
                        retval = dt9812_read_info(dev, 1, &fw, sizeof(fw));
                        if (retval == 0) {
                                dev_info(&interface->dev,
                                         "usb_reset_configuration succeded "
                                         "after %d iterations\n", i);
                                break;
                        }
                }
        }

        if (dt9812_read_info(dev, 1, &dev->vendor, sizeof(dev->vendor)) != 0) {
                err("Failed to read vendor.");
                retval = -ENODEV;
                goto error;
        }
        if (dt9812_read_info(dev, 3, &dev->product, sizeof(dev->product)) != 0) {
                err("Failed to read product.");
                retval = -ENODEV;
                goto error;
        }
        if (dt9812_read_info(dev, 5, &dev->device, sizeof(dev->device)) != 0) {
                err("Failed to read device.");
                retval = -ENODEV;
                goto error;
        }
        if (dt9812_read_info(dev, 7, &dev->serial, sizeof(dev->serial)) != 0) {
                err("Failed to read serial.");
                retval = -ENODEV;
                goto error;
        }

        dev->vendor = le16_to_cpu(dev->vendor);
        dev->product = le16_to_cpu(dev->product);
        dev->device = le16_to_cpu(dev->device);
        dev->serial = le32_to_cpu(dev->serial);
        switch (dev->device) {
        case DT9812_DEVID_DT9812_10:
                dev->analog_out_shadow[0] = 0x0800;
                dev->analog_out_shadow[1] = 0x800;
                break;
        case DT9812_DEVID_DT9812_2PT5:
                dev->analog_out_shadow[0] = 0x0000;
                dev->analog_out_shadow[1] = 0x0000;
                break;
        }
        dev->digital_out_shadow = 0;

        /* save our data pointer in this interface device */
        usb_set_intfdata(interface, dev);

        /* let the user know what node this device is now attached to */
        dev_info(&interface->dev, "USB DT9812 (%4.4x.%4.4x.%4.4x) #0x%8.8x\n",
                 dev->vendor, dev->product, dev->device, dev->serial);

        down(&dt9812_mutex);
        {
                /* Find a slot for the USB device */
                struct slot_dt9812 *first = NULL;
                struct slot_dt9812 *best = NULL;

                for (i = 0; i < DT9812_NUM_SLOTS; i++) {
                        if (!first && !dt9812[i].usb && dt9812[i].serial == 0)
                                first = &dt9812[i];
                        if (!best && dt9812[i].serial == dev->serial)
                                best = &dt9812[i];
                }

                if (!best)
                        best = first;

                if (best) {
                        down(&best->mutex);
                        best->usb = dev;
                        dev->slot = best;
                        up(&best->mutex);
                }
        }
        up(&dt9812_mutex);

        return 0;

error:
        if (dev)
                kref_put(&dev->kref, dt9812_delete);
        return retval;
}

static void dt9812_disconnect(struct usb_interface *interface)
{
        struct usb_dt9812 *dev;
        int minor = interface->minor;

        down(&dt9812_mutex);
        dev = usb_get_intfdata(interface);
        if (dev->slot) {
                down(&dev->slot->mutex);
                dev->slot->usb = NULL;
                up(&dev->slot->mutex);
                dev->slot = NULL;
        }
        usb_set_intfdata(interface, NULL);
        up(&dt9812_mutex);

        /* queue final destruction */
        kref_put(&dev->kref, dt9812_delete);

        dev_info(&interface->dev, "USB Dt9812 #%d now disconnected\n", minor);
}

static struct usb_driver dt9812_usb_driver = {
        .name = "dt9812",
        .probe = dt9812_probe,
        .disconnect = dt9812_disconnect,
        .id_table = dt9812_table,
};

/*
 * Comedi functions
 */

static void dt9812_comedi_open(struct comedi_device *dev)
{
        down(&devpriv->slot->mutex);
        if (devpriv->slot->usb) {
                /* We have an attached device, fill in current range info */
                struct comedi_subdevice *s;

                s = &dev->subdevices[0];
                s->n_chan = 8;
                s->maxdata = 1;

                s = &dev->subdevices[1];
                s->n_chan = 8;
                s->maxdata = 1;

                s = &dev->subdevices[2];
                s->n_chan = 8;
                switch (devpriv->slot->usb->device) {
                case 0:{
                                s->maxdata = 4095;
                                s->range_table = &dt9812_10_ain_range;
                        }
                        break;
                case 1:{
                                s->maxdata = 4095;
                                s->range_table = &dt9812_2pt5_ain_range;
                        }
                        break;
                }

                s = &dev->subdevices[3];
                s->n_chan = 2;
                switch (devpriv->slot->usb->device) {
                case 0:{
                                s->maxdata = 4095;
                                s->range_table = &dt9812_10_aout_range;
                        }
                        break;
                case 1:{
                                s->maxdata = 4095;
                                s->range_table = &dt9812_2pt5_aout_range;
                        }
                        break;
                }
        }
        up(&devpriv->slot->mutex);
}

static int dt9812_di_rinsn(struct comedi_device *dev,
                           struct comedi_subdevice *s, struct comedi_insn *insn,
                           unsigned int *data)
{
        int n;
        u8 bits = 0;

        dt9812_digital_in(devpriv->slot, &bits);
        for (n = 0; n < insn->n; n++)
                data[n] = ((1 << insn->chanspec) & bits) != 0;
        return n;
}

static int dt9812_do_winsn(struct comedi_device *dev,
                           struct comedi_subdevice *s, struct comedi_insn *insn,
                           unsigned int *data)
{
        int n;
        u8 bits = 0;

        dt9812_digital_out_shadow(devpriv->slot, &bits);
        for (n = 0; n < insn->n; n++) {
                u8 mask = 1 << insn->chanspec;

                bits &= ~mask;
                if (data[n])
                        bits |= mask;
        }
        dt9812_digital_out(devpriv->slot, bits);
        return n;
}

static int dt9812_ai_rinsn(struct comedi_device *dev,
                           struct comedi_subdevice *s, struct comedi_insn *insn,
                           unsigned int *data)
{
        int n;

        for (n = 0; n < insn->n; n++) {
                u16 value = 0;

                dt9812_analog_in(devpriv->slot, insn->chanspec, &value,
                                 DT9812_GAIN_1);
                data[n] = value;
        }
        return n;
}

static int dt9812_ao_rinsn(struct comedi_device *dev,
                           struct comedi_subdevice *s, struct comedi_insn *insn,
                           unsigned int *data)
{
        int n;
        u16 value;

        for (n = 0; n < insn->n; n++) {
                value = 0;
                dt9812_analog_out_shadow(devpriv->slot, insn->chanspec, &value);
                data[n] = value;
        }

        return n;
}

static int dt9812_ao_winsn(struct comedi_device *dev,
                           struct comedi_subdevice *s, struct comedi_insn *insn,
                           unsigned int *data)
{
        int n;

        for (n = 0; n < insn->n; n++)
                dt9812_analog_out(devpriv->slot, insn->chanspec, data[n]);
        return n;
}

static int dt9812_attach(struct comedi_device *dev, struct comedi_devconfig *it)
{
        int i;
        struct comedi_subdevice *s;

        dev->board_name = "dt9812";

        if (alloc_private(dev, sizeof(struct comedi_dt9812)) < 0)
                return -ENOMEM;

        /*
         * Special open routine, since USB unit may be unattached at
         * comedi_config time, hence range can not be determined
         */
        dev->open = dt9812_comedi_open;

        devpriv->serial = it->options[0];

        /* Allocate subdevices */
        if (alloc_subdevices(dev, 4) < 0)
                return -ENOMEM;

        /* digital input subdevice */
        s = dev->subdevices + 0;
        s->type = COMEDI_SUBD_DI;
        s->subdev_flags = SDF_READABLE;
        s->n_chan = 0;
        s->maxdata = 1;
        s->range_table = &range_digital;
        s->insn_read = &dt9812_di_rinsn;

        /* digital output subdevice */
        s = dev->subdevices + 1;
        s->type = COMEDI_SUBD_DO;
        s->subdev_flags = SDF_WRITEABLE;
        s->n_chan = 0;
        s->maxdata = 1;
        s->range_table = &range_digital;
        s->insn_write = &dt9812_do_winsn;

        /* analog input subdevice */
        s = dev->subdevices + 2;
        s->type = COMEDI_SUBD_AI;
        s->subdev_flags = SDF_READABLE | SDF_GROUND;
        s->n_chan = 0;
        s->maxdata = 1;
        s->range_table = NULL;
        s->insn_read = &dt9812_ai_rinsn;

        /* analog output subdevice */
        s = dev->subdevices + 3;
        s->type = COMEDI_SUBD_AO;
        s->subdev_flags = SDF_WRITEABLE;
        s->n_chan = 0;
        s->maxdata = 1;
        s->range_table = NULL;
        s->insn_write = &dt9812_ao_winsn;
        s->insn_read = &dt9812_ao_rinsn;

        printk(KERN_INFO "comedi%d: successfully attached to dt9812.\n",
               dev->minor);

        down(&dt9812_mutex);
        /* Find a slot for the comedi device */
        {
                struct slot_dt9812 *first = NULL;
                struct slot_dt9812 *best = NULL;
                for (i = 0; i < DT9812_NUM_SLOTS; i++) {
                        if (!first && !dt9812[i].comedi) {
                                /* First free slot from comedi side */
                                first = &dt9812[i];
                        }
                        if (!best &&
                            dt9812[i].usb &&
                            dt9812[i].usb->serial == devpriv->serial) {
                                /* We have an attaced device with matching ID */
                                best = &dt9812[i];
                        }
                }
                if (!best)
                        best = first;
                if (best) {
                        down(&best->mutex);
                        best->comedi = devpriv;
                        best->serial = devpriv->serial;
                        devpriv->slot = best;
                        up(&best->mutex);
                }
        }
        up(&dt9812_mutex);

        return 0;
}

static int dt9812_detach(struct comedi_device *dev)
{
        return 0;
}

static struct comedi_driver dt9812_comedi_driver = {
        .module = THIS_MODULE,
        .driver_name = "dt9812",
        .attach = dt9812_attach,
        .detach = dt9812_detach,
};

static int __init usb_dt9812_init(void)
{
        int result, i;

        /* Initialize all driver slots */
        for (i = 0; i < DT9812_NUM_SLOTS; i++) {
                init_MUTEX(&dt9812[i].mutex);
                dt9812[i].serial = 0;
                dt9812[i].usb = NULL;
                dt9812[i].comedi = NULL;
        }
        dt9812[12].serial = 0x0;

        /* register with the USB subsystem */
        result = usb_register(&dt9812_usb_driver);
        if (result) {
                printk(KERN_ERR KBUILD_MODNAME
                       ": usb_register failed. Error number %d\n", result);
                return result;
        }
        /* register with comedi */
        result = comedi_driver_register(&dt9812_comedi_driver);
        if (result) {
                usb_deregister(&dt9812_usb_driver);
                err("comedi_driver_register failed. Error number %d", result);
        }

        return result;
}

static void __exit usb_dt9812_exit(void)
{
        /* unregister with comedi */
        comedi_driver_unregister(&dt9812_comedi_driver);

        /* deregister this driver with the USB subsystem */
        usb_deregister(&dt9812_usb_driver);
}

module_init(usb_dt9812_init);
module_exit(usb_dt9812_exit);

MODULE_AUTHOR("Anders Blomdell <anders.blomdell@control.lth.se>");
MODULE_DESCRIPTION("Comedi DT9812 driver");
MODULE_LICENSE("GPL");