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flexcop-i2c.c

/*
 * This file is part of linux driver the digital TV devices equipped with B2C2 FlexcopII(b)/III
 *
 * flexcop-i2c.c - flexcop internal 2Wire bus (I2C) and dvb i2c initialization
 *
 * see flexcop.c for copyright information.
 */
#include "flexcop.h"

#define FC_MAX_I2C_RETRIES 100000

static int flexcop_i2c_operation(struct flexcop_device *fc, flexcop_ibi_value *r100)
{
      int i;
      flexcop_ibi_value r;

      r100->tw_sm_c_100.working_start = 1;
      deb_i2c("r100 before: %08x\n",r100->raw);

      fc->write_ibi_reg(fc, tw_sm_c_100, ibi_zero);
      fc->write_ibi_reg(fc, tw_sm_c_100, *r100); /* initiating i2c operation */

      for (i = 0; i < FC_MAX_I2C_RETRIES; i++) {
            r = fc->read_ibi_reg(fc, tw_sm_c_100);

            if (!r.tw_sm_c_100.no_base_addr_ack_error) {
                  if (r.tw_sm_c_100.st_done) {  /* && !r.tw_sm_c_100.working_start */
                        *r100 = r;
                        deb_i2c("i2c success\n");
                        return 0;
                  }
            } else {
                  deb_i2c("suffering from an i2c ack_error\n");
                  return -EREMOTEIO;
            }
      }
      deb_i2c("tried %d times i2c operation, never finished or too many ack errors.\n",i);
      return -EREMOTEIO;
}

static int flexcop_i2c_read4(struct flexcop_device *fc, flexcop_ibi_value r100, u8 *buf)
{
      flexcop_ibi_value r104;
      int len = r100.tw_sm_c_100.total_bytes, /* remember total_bytes is buflen-1 */
            ret;

      if ((ret = flexcop_i2c_operation(fc,&r100)) != 0) {
            /* The Cablestar needs a different kind of i2c-transfer (does not
             * support "Repeat Start"):
             * wait for the ACK failure,
             * and do a subsequent read with the Bit 30 enabled
             */
            r100.tw_sm_c_100.no_base_addr_ack_error = 1;
            if ((ret = flexcop_i2c_operation(fc,&r100)) != 0) {
                  deb_i2c("no_base_addr read failed. %d\n",ret);
                  return ret;
            }
      }

      buf[0] = r100.tw_sm_c_100.data1_reg;

      if (len > 0) {
            r104 = fc->read_ibi_reg(fc,tw_sm_c_104);
            deb_i2c("read: r100: %08x, r104: %08x\n",r100.raw,r104.raw);

            /* there is at least one more byte, otherwise we wouldn't be here */
            buf[1] = r104.tw_sm_c_104.data2_reg;
            if (len > 1) buf[2] = r104.tw_sm_c_104.data3_reg;
            if (len > 2) buf[3] = r104.tw_sm_c_104.data4_reg;
      }

      return 0;
}

static int flexcop_i2c_write4(struct flexcop_device *fc, flexcop_ibi_value r100, u8 *buf)
{
      flexcop_ibi_value r104;
      int len = r100.tw_sm_c_100.total_bytes; /* remember total_bytes is buflen-1 */
      r104.raw = 0;

      /* there is at least one byte, otherwise we wouldn't be here */
      r100.tw_sm_c_100.data1_reg = buf[0];

      r104.tw_sm_c_104.data2_reg = len > 0 ? buf[1] : 0;
      r104.tw_sm_c_104.data3_reg = len > 1 ? buf[2] : 0;
      r104.tw_sm_c_104.data4_reg = len > 2 ? buf[3] : 0;

      deb_i2c("write: r100: %08x, r104: %08x\n",r100.raw,r104.raw);

      /* write the additional i2c data before doing the actual i2c operation */
      fc->write_ibi_reg(fc,tw_sm_c_104,r104);
      return flexcop_i2c_operation(fc,&r100);
}

int flexcop_i2c_request(struct flexcop_device *fc, flexcop_access_op_t op,
            flexcop_i2c_port_t port, u8 chipaddr, u8 addr, u8 *buf, u16 len)
{
      int ret;
      u16 bytes_to_transfer;
      flexcop_ibi_value r100;

      deb_i2c("op = %d\n",op);
      r100.raw = 0;
      r100.tw_sm_c_100.chipaddr = chipaddr;
      r100.tw_sm_c_100.twoWS_rw = op;
      r100.tw_sm_c_100.twoWS_port_reg = port;

      while (len != 0) {
            bytes_to_transfer = len > 4 ? 4 : len;

            r100.tw_sm_c_100.total_bytes = bytes_to_transfer - 1;
            r100.tw_sm_c_100.baseaddr = addr;

            if (op == FC_READ)
                  ret = flexcop_i2c_read4(fc, r100, buf);
            else
                  ret = flexcop_i2c_write4(fc,r100, buf);

            if (ret < 0)
                  return ret;

            buf  += bytes_to_transfer;
            addr += bytes_to_transfer;
            len  -= bytes_to_transfer;
      };

      return 0;
}
/* exported for PCI i2c */
EXPORT_SYMBOL(flexcop_i2c_request);

/* master xfer callback for demodulator */
static int flexcop_master_xfer(struct i2c_adapter *i2c_adap, struct i2c_msg msgs[], int num)
{
      struct flexcop_device *fc = i2c_get_adapdata(i2c_adap);
      int i, ret = 0;

      /* Some drivers use 1 byte or 0 byte reads as probes, which this
       * driver doesn't support.  These probes will always fail, so this
       * hack makes them always succeed.  If one knew how, it would of
       * course be better to actually do the read.  */
      if (num == 1 && msgs[0].flags == I2C_M_RD && msgs[0].len <= 1)
            return 1;

      if (mutex_lock_interruptible(&fc->i2c_mutex))
            return -ERESTARTSYS;

      /* reading */
      if (num == 2 &&
            msgs[0].flags == 0 &&
            msgs[1].flags == I2C_M_RD &&
            msgs[0].buf != NULL &&
            msgs[1].buf != NULL) {

            ret = fc->i2c_request(fc, FC_READ, FC_I2C_PORT_DEMOD, msgs[0].addr, msgs[0].buf[0], msgs[1].buf, msgs[1].len);

      } else for (i = 0; i < num; i++) { /* writing command */
            if (msgs[i].flags != 0 || msgs[i].buf == NULL || msgs[i].len < 2) {
                  ret = -EINVAL;
                  break;
            }

            ret = fc->i2c_request(fc, FC_WRITE, FC_I2C_PORT_DEMOD, msgs[i].addr, msgs[i].buf[0], &msgs[i].buf[1], msgs[i].len - 1);
      }

      if (ret < 0)
            err("i2c master_xfer failed");
      else
            ret = num;

      mutex_unlock(&fc->i2c_mutex);

      return ret;
}

static u32 flexcop_i2c_func(struct i2c_adapter *adapter)
{
      return I2C_FUNC_I2C;
}

static struct i2c_algorithm flexcop_algo = {
      .master_xfer      = flexcop_master_xfer,
      .functionality    = flexcop_i2c_func,
};

int flexcop_i2c_init(struct flexcop_device *fc)
{
      int ret;

      mutex_init(&fc->i2c_mutex);

      memset(&fc->i2c_adap, 0, sizeof(struct i2c_adapter));
      strncpy(fc->i2c_adap.name, "B2C2 FlexCop device",
            sizeof(fc->i2c_adap.name));

      i2c_set_adapdata(&fc->i2c_adap,fc);

      fc->i2c_adap.class          = I2C_CLASS_TV_DIGITAL;
      fc->i2c_adap.algo       = &flexcop_algo;
      fc->i2c_adap.algo_data  = NULL;
      fc->i2c_adap.dev.parent = fc->dev;

      if ((ret = i2c_add_adapter(&fc->i2c_adap)) < 0)
            return ret;

      fc->init_state |= FC_STATE_I2C_INIT;
      return 0;
}

void flexcop_i2c_exit(struct flexcop_device *fc)
{
      if (fc->init_state & FC_STATE_I2C_INIT)
            i2c_del_adapter(&fc->i2c_adap);

      fc->init_state &= ~FC_STATE_I2C_INIT;
}

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