// SPDX-License-Identifier: GPL-2.0+
/*
 * 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
 */

/*
 * Driver: dt9812
 * Description: Data Translation DT9812 USB module
 * Devices: [Data Translation] DT9812 (dt9812)
 * Author: anders.blomdell@control.lth.se (Anders Blomdell)
 * Status: in development
 * 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/module.h>
#include <linux/errno.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
#include <linux/comedi/comedi_usb.h>

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

/* usb_bulk_msg() timeout in milliseconds */
#define DT9812_USB_TIMEOUT              1000

/*
 * 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 */
};

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 {
        __le16 numbytes;
        __le16 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 {
        __le32 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;
};

struct dt9812_private {
        struct mutex mut;
        struct {
                __u8 addr;
                size_t size;
        } cmd_wr, cmd_rd;
        u16 device;
};

static int dt9812_read_info(struct comedi_device *dev,
                            int offset, void *buf, size_t buf_size)
{
        struct usb_device *usb = comedi_to_usb_dev(dev);
        struct dt9812_private *devpriv = dev->private;
        struct dt9812_usb_cmd *cmd;
        size_t tbuf_size;
        int count, ret;
        void *tbuf;

        tbuf_size = max(sizeof(*cmd), buf_size);

        tbuf = kzalloc(tbuf_size, GFP_KERNEL);
        if (!tbuf)
                return -ENOMEM;

        cmd = tbuf;

        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!! */
        ret = usb_bulk_msg(usb, usb_sndbulkpipe(usb, devpriv->cmd_wr.addr),
                           cmd, sizeof(*cmd), &count, DT9812_USB_TIMEOUT);
        if (ret)
                goto out;

        ret = usb_bulk_msg(usb, usb_rcvbulkpipe(usb, devpriv->cmd_rd.addr),
                           tbuf, buf_size, &count, DT9812_USB_TIMEOUT);
        if (!ret) {
                if (count == buf_size)
                        memcpy(buf, tbuf, buf_size);
                else
                        ret = -EREMOTEIO;
        }
out:
        kfree(tbuf);

        return ret;
}

static int dt9812_read_multiple_registers(struct comedi_device *dev,
                                          int reg_count, u8 *address,
                                          u8 *value)
{
        struct usb_device *usb = comedi_to_usb_dev(dev);
        struct dt9812_private *devpriv = dev->private;
        struct dt9812_usb_cmd *cmd;
        int i, count, ret;
        size_t buf_size;
        void *buf;

        buf_size = max_t(size_t, sizeof(*cmd), reg_count);

        buf = kzalloc(buf_size, GFP_KERNEL);
        if (!buf)
                return -ENOMEM;

        cmd = buf;

        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!! */
        ret = usb_bulk_msg(usb, usb_sndbulkpipe(usb, devpriv->cmd_wr.addr),
                           cmd, sizeof(*cmd), &count, DT9812_USB_TIMEOUT);
        if (ret)
                goto out;

        ret = usb_bulk_msg(usb, usb_rcvbulkpipe(usb, devpriv->cmd_rd.addr),
                           buf, reg_count, &count, DT9812_USB_TIMEOUT);
        if (!ret) {
                if (count == reg_count)
                        memcpy(value, buf, reg_count);
                else
                        ret = -EREMOTEIO;
        }
out:
        kfree(buf);

        return ret;
}

static int dt9812_write_multiple_registers(struct comedi_device *dev,
                                           int reg_count, u8 *address,
                                           u8 *value)
{
        struct usb_device *usb = comedi_to_usb_dev(dev);
        struct dt9812_private *devpriv = dev->private;
        struct dt9812_usb_cmd *cmd;
        int i, count;
        int ret;

        cmd = kzalloc_obj(*cmd);
        if (!cmd)
                return -ENOMEM;

        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!! */
        ret = usb_bulk_msg(usb, usb_sndbulkpipe(usb, devpriv->cmd_wr.addr),
                           cmd, sizeof(*cmd), &count, DT9812_USB_TIMEOUT);
        kfree(cmd);

        return ret;
}

static int dt9812_rmw_multiple_registers(struct comedi_device *dev,
                                         int reg_count,
                                         struct dt9812_rmw_byte *rmw)
{
        struct usb_device *usb = comedi_to_usb_dev(dev);
        struct dt9812_private *devpriv = dev->private;
        struct dt9812_usb_cmd *cmd;
        int i, count;
        int ret;

        cmd = kzalloc_obj(*cmd);
        if (!cmd)
                return -ENOMEM;

        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!! */
        ret = usb_bulk_msg(usb, usb_sndbulkpipe(usb, devpriv->cmd_wr.addr),
                           cmd, sizeof(*cmd), &count, DT9812_USB_TIMEOUT);
        kfree(cmd);

        return ret;
}

static int dt9812_digital_in(struct comedi_device *dev, u8 *bits)
{
        struct dt9812_private *devpriv = dev->private;
        u8 reg[2] = { F020_SFR_P3, F020_SFR_P1 };
        u8 value[2];
        int ret;

        mutex_lock(&devpriv->mut);
        ret = dt9812_read_multiple_registers(dev, 2, reg, value);
        if (ret == 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);
        }
        mutex_unlock(&devpriv->mut);

        return ret;
}

static int dt9812_digital_out(struct comedi_device *dev, u8 bits)
{
        struct dt9812_private *devpriv = dev->private;
        u8 reg[1] = { F020_SFR_P2 };
        u8 value[1] = { bits };
        int ret;

        mutex_lock(&devpriv->mut);
        ret = dt9812_write_multiple_registers(dev, 1, reg, value);
        mutex_unlock(&devpriv->mut);

        return ret;
}

static void dt9812_configure_mux(struct comedi_device *dev,
                                 struct dt9812_rmw_byte *rmw, int channel)
{
        struct dt9812_private *devpriv = dev->private;

        if (devpriv->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 comedi_device *dev,
                                  struct dt9812_rmw_byte *rmw,
                                  enum dt9812_gain gain)
{
        struct dt9812_private *devpriv = dev->private;

        /* In the DT9812/10V, there is an external gain of 0.5 */
        if (devpriv->device == DT9812_DEVID_DT9812_10)
                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;
        default:
                /* this should never happen, just use a gain of 1 */
        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;
        }
}

static int dt9812_analog_in(struct comedi_device *dev,
                            int channel, u16 *value, enum dt9812_gain gain)
{
        struct dt9812_private *devpriv = dev->private;
        struct dt9812_rmw_byte rmw[3];
        u8 reg[3] = {
                F020_SFR_ADC0CN,
                F020_SFR_ADC0H,
                F020_SFR_ADC0L
        };
        u8 val[3];
        int ret;

        mutex_lock(&devpriv->mut);

        /* 1 select the gain */
        dt9812_configure_gain(dev, &rmw[0], gain);

        /* 2 set the MUX to select the channel */
        dt9812_configure_mux(dev, &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;

        ret = dt9812_rmw_multiple_registers(dev, 3, rmw);
        if (ret)
                goto exit;

        /* read the status and ADC */
        ret = dt9812_read_multiple_registers(dev, 3, reg, val);
        if (ret)
                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 (devpriv->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:
        mutex_unlock(&devpriv->mut);

        return ret;
}

static int dt9812_analog_out(struct comedi_device *dev, int channel, u16 value)
{
        struct dt9812_private *devpriv = dev->private;
        struct dt9812_rmw_byte rmw[3];
        int ret;

        mutex_lock(&devpriv->mut);

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

                /* 3. load msb 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 lsb of DAC value first */
                rmw[1].address = F020_SFR_DAC1L;
                rmw[1].and_mask = 0xff;
                rmw[1].or_value = value & 0xff;

                /* 3. load msb 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;
        }
        ret = dt9812_rmw_multiple_registers(dev, 3, rmw);

        mutex_unlock(&devpriv->mut);

        return ret;
}

static int dt9812_di_insn_bits(struct comedi_device *dev,
                               struct comedi_subdevice *s,
                               struct comedi_insn *insn,
                               unsigned int *data)
{
        u8 bits = 0;
        int ret;

        ret = dt9812_digital_in(dev, &bits);
        if (ret)
                return ret;

        data[1] = bits;

        return insn->n;
}

static int dt9812_do_insn_bits(struct comedi_device *dev,
                               struct comedi_subdevice *s,
                               struct comedi_insn *insn,
                               unsigned int *data)
{
        if (comedi_dio_update_state(s, data))
                dt9812_digital_out(dev, s->state);

        data[1] = s->state;

        return insn->n;
}

static int dt9812_ai_insn_read(struct comedi_device *dev,
                               struct comedi_subdevice *s,
                               struct comedi_insn *insn,
                               unsigned int *data)
{
        unsigned int chan = CR_CHAN(insn->chanspec);
        u16 val = 0;
        int ret;
        int i;

        for (i = 0; i < insn->n; i++) {
                ret = dt9812_analog_in(dev, chan, &val, DT9812_GAIN_1);
                if (ret)
                        return ret;
                data[i] = val;
        }

        return insn->n;
}

static int dt9812_ao_insn_read(struct comedi_device *dev,
                               struct comedi_subdevice *s,
                               struct comedi_insn *insn,
                               unsigned int *data)
{
        struct dt9812_private *devpriv = dev->private;
        int ret;

        mutex_lock(&devpriv->mut);
        ret = comedi_readback_insn_read(dev, s, insn, data);
        mutex_unlock(&devpriv->mut);

        return ret;
}

static int dt9812_ao_insn_write(struct comedi_device *dev,
                                struct comedi_subdevice *s,
                                struct comedi_insn *insn,
                                unsigned int *data)
{
        unsigned int chan = CR_CHAN(insn->chanspec);
        int i;

        for (i = 0; i < insn->n; i++) {
                unsigned int val = data[i];
                int ret;

                ret = dt9812_analog_out(dev, chan, val);
                if (ret)
                        return ret;

                s->readback[chan] = val;
        }

        return insn->n;
}

static int dt9812_find_endpoints(struct comedi_device *dev)
{
        struct usb_interface *intf = comedi_to_usb_interface(dev);
        struct usb_host_interface *host = intf->cur_altsetting;
        struct dt9812_private *devpriv = dev->private;
        struct usb_endpoint_descriptor *ep;
        int i;

        if (host->desc.bNumEndpoints != 5) {
                dev_err(dev->class_dev, "Wrong number of endpoints\n");
                return -ENODEV;
        }

        for (i = 0; i < host->desc.bNumEndpoints; ++i) {
                int dir = -1;

                ep = &host->endpoint[i].desc;
                switch (i) {
                case 0:
                        /* unused message pipe */
                        dir = USB_DIR_IN;
                        break;
                case 1:
                        dir = USB_DIR_OUT;
                        devpriv->cmd_wr.addr = ep->bEndpointAddress;
                        devpriv->cmd_wr.size = usb_endpoint_maxp(ep);
                        break;
                case 2:
                        dir = USB_DIR_IN;
                        devpriv->cmd_rd.addr = ep->bEndpointAddress;
                        devpriv->cmd_rd.size = usb_endpoint_maxp(ep);
                        break;
                case 3:
                        /* unused write stream */
                        dir = USB_DIR_OUT;
                        break;
                case 4:
                        /* unused read stream */
                        dir = USB_DIR_IN;
                        break;
                }
                if ((ep->bEndpointAddress & USB_DIR_IN) != dir) {
                        dev_err(dev->class_dev,
                                "Endpoint has wrong direction\n");
                        return -ENODEV;
                }
        }
        return 0;
}

static int dt9812_reset_device(struct comedi_device *dev)
{
        struct usb_device *usb = comedi_to_usb_dev(dev);
        struct dt9812_private *devpriv = dev->private;
        u32 serial;
        u16 vendor;
        u16 product;
        u8 tmp8;
        __le16 tmp16;
        __le32 tmp32;
        int ret;
        int i;

        ret = dt9812_read_info(dev, 0, &tmp8, sizeof(tmp8));
        if (ret) {
                /*
                 * Seems like a configuration reset is necessary if driver is
                 * reloaded while device is attached
                 */
                usb_reset_configuration(usb);
                for (i = 0; i < 10; i++) {
                        ret = dt9812_read_info(dev, 1, &tmp8, sizeof(tmp8));
                        if (ret == 0)
                                break;
                }
                if (ret) {
                        dev_err(dev->class_dev,
                                "unable to reset configuration\n");
                        return ret;
                }
        }

        ret = dt9812_read_info(dev, 1, &tmp16, sizeof(tmp16));
        if (ret) {
                dev_err(dev->class_dev, "failed to read vendor id\n");
                return ret;
        }
        vendor = le16_to_cpu(tmp16);

        ret = dt9812_read_info(dev, 3, &tmp16, sizeof(tmp16));
        if (ret) {
                dev_err(dev->class_dev, "failed to read product id\n");
                return ret;
        }
        product = le16_to_cpu(tmp16);

        ret = dt9812_read_info(dev, 5, &tmp16, sizeof(tmp16));
        if (ret) {
                dev_err(dev->class_dev, "failed to read device id\n");
                return ret;
        }
        devpriv->device = le16_to_cpu(tmp16);

        ret = dt9812_read_info(dev, 7, &tmp32, sizeof(tmp32));
        if (ret) {
                dev_err(dev->class_dev, "failed to read serial number\n");
                return ret;
        }
        serial = le32_to_cpu(tmp32);

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

        if (devpriv->device != DT9812_DEVID_DT9812_10 &&
            devpriv->device != DT9812_DEVID_DT9812_2PT5) {
                dev_err(dev->class_dev, "Unsupported device!\n");
                return -EINVAL;
        }

        return 0;
}

static int dt9812_auto_attach(struct comedi_device *dev,
                              unsigned long context)
{
        struct usb_interface *intf = comedi_to_usb_interface(dev);
        struct dt9812_private *devpriv;
        struct comedi_subdevice *s;
        bool is_unipolar;
        int ret;
        int i;

        devpriv = comedi_alloc_devpriv(dev, sizeof(*devpriv));
        if (!devpriv)
                return -ENOMEM;

        mutex_init(&devpriv->mut);
        usb_set_intfdata(intf, devpriv);

        ret = dt9812_find_endpoints(dev);
        if (ret)
                return ret;

        ret = dt9812_reset_device(dev);
        if (ret)
                return ret;

        is_unipolar = (devpriv->device == DT9812_DEVID_DT9812_2PT5);

        ret = comedi_alloc_subdevices(dev, 4);
        if (ret)
                return ret;

        /* Digital Input subdevice */
        s = &dev->subdevices[0];
        s->type         = COMEDI_SUBD_DI;
        s->subdev_flags = SDF_READABLE;
        s->n_chan       = 8;
        s->maxdata      = 1;
        s->range_table  = &range_digital;
        s->insn_bits    = dt9812_di_insn_bits;

        /* Digital Output subdevice */
        s = &dev->subdevices[1];
        s->type         = COMEDI_SUBD_DO;
        s->subdev_flags = SDF_WRITABLE;
        s->n_chan       = 8;
        s->maxdata      = 1;
        s->range_table  = &range_digital;
        s->insn_bits    = dt9812_do_insn_bits;

        /* Analog Input subdevice */
        s = &dev->subdevices[2];
        s->type         = COMEDI_SUBD_AI;
        s->subdev_flags = SDF_READABLE | SDF_GROUND;
        s->n_chan       = 8;
        s->maxdata      = 0x0fff;
        s->range_table  = is_unipolar ? &range_unipolar2_5 : &range_bipolar10;
        s->insn_read    = dt9812_ai_insn_read;

        /* Analog Output subdevice */
        s = &dev->subdevices[3];
        s->type         = COMEDI_SUBD_AO;
        s->subdev_flags = SDF_WRITABLE;
        s->n_chan       = 2;
        s->maxdata      = 0x0fff;
        s->range_table  = is_unipolar ? &range_unipolar2_5 : &range_bipolar10;
        s->insn_write   = dt9812_ao_insn_write;
        s->insn_read    = dt9812_ao_insn_read;

        ret = comedi_alloc_subdev_readback(s);
        if (ret)
                return ret;

        for (i = 0; i < s->n_chan; i++)
                s->readback[i] = is_unipolar ? 0x0000 : 0x0800;

        return 0;
}

static void dt9812_detach(struct comedi_device *dev)
{
        struct usb_interface *intf = comedi_to_usb_interface(dev);
        struct dt9812_private *devpriv = dev->private;

        if (!devpriv)
                return;

        mutex_destroy(&devpriv->mut);
        usb_set_intfdata(intf, NULL);
}

static struct comedi_driver dt9812_driver = {
        .driver_name    = "dt9812",
        .module         = THIS_MODULE,
        .auto_attach    = dt9812_auto_attach,
        .detach         = dt9812_detach,
};

static int dt9812_usb_probe(struct usb_interface *intf,
                            const struct usb_device_id *id)
{
        return comedi_usb_auto_config(intf, &dt9812_driver, id->driver_info);
}

static const struct usb_device_id dt9812_usb_table[] = {
        { USB_DEVICE(0x0867, 0x9812) },
        { }
};
MODULE_DEVICE_TABLE(usb, dt9812_usb_table);

static struct usb_driver dt9812_usb_driver = {
        .name           = "dt9812",
        .id_table       = dt9812_usb_table,
        .probe          = dt9812_usb_probe,
        .disconnect     = comedi_usb_auto_unconfig,
};
module_comedi_usb_driver(dt9812_driver, dt9812_usb_driver);

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