path: root/cpu/mpc85xx/i2c.c

/*
 * (C) Copyright 2003,Motorola Inc.
 * Xianghua Xiao <x.xiao@motorola.com>
 * Adapted for Motorola 85xx chip.
 *
 * (C) Copyright 2003
 * Gleb Natapov <gnatapov@mrv.com>
 * Some bits are taken from linux driver writen by adrian@humboldt.co.uk
 *
 * Hardware I2C driver for MPC107 PCI bridge.
 *
 * See file CREDITS for list of people who contributed to this
 * project.
 *
 * 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., 59 Temple Place, Suite 330, Boston,
 * MA 02111-1307 USA
 */

#include <common.h>
#include <command.h>

#define DEBUG

#if defined(DEBUG)
#define DEB(x)      x
#else
#define DEB(x)
#endif

#ifdef CONFIG_HARD_I2C
#include <i2c.h>

#define TIMEOUT (CFG_HZ/4)

#define I2C_Addr ((unsigned *)(CFG_CCSRBAR + 0x3000))

#define I2CADR  &I2C_Addr[0]
#define I2CFDR  &I2C_Addr[1]
#define I2CCCR  &I2C_Addr[2]
#define I2CCSR  &I2C_Addr[3]
#define I2CCDR  &I2C_Addr[4]
#define I2CDFSRR &I2C_Addr[5]

#define I2C_READ  1
#define I2C_WRITE 0

/* taken from linux include/asm-ppc/io.h */
inline unsigned in_le32(volatile unsigned *addr)
{
  unsigned ret;

  __asm__ __volatile__("lwbrx %0,0,%1;\n"
		       "twi 0,%0,0;\n"
		       "isync" : "=r" (ret) :
		       "r" (addr), "m" (*addr));
  return ret;
}

inline void out_le32(volatile unsigned *addr, int val)
{
  __asm__ __volatile__("stwbrx %1,0,%2; eieio" : "=m" (*addr) :
		       "r" (val), "r" (addr));
}

#define writel(val, addr) out_le32(addr, val)
#define readl(addr) in_le32(addr)

void
i2c_init(int speed, int slaveadd)
{
  /* stop I2C controller */
  writel (0x0, I2CCCR);
  /* set clock */
  writel (0x3f, I2CFDR);
  /* set default filter */
  writel (0x10,I2CDFSRR);
  /* write slave address */
  writel (slaveadd, I2CADR);
  /* clear status register */
  writel (0x0, I2CCSR);
  /* start I2C controller */
  writel (MPC85xx_I2CCR_MEN, I2CCCR);
}

static __inline__ int
i2c_wait4bus (void)
{
  ulong timeval = get_timer (0);

  while (readl (I2CCSR) & MPC85xx_I2CSR_MBB)
    if (get_timer (timeval) > TIMEOUT)
      return -1;

  return 0;
}

static __inline__ int
i2c_wait (int write)
{
  u32 csr;
  ulong timeval = get_timer (0);

  do
    {
      csr  = readl (I2CCSR);

      if (!(csr & MPC85xx_I2CSR_MIF))
	continue;

      writel (0x0, I2CCSR);

      if (csr & MPC85xx_I2CSR_MAL)
	{
	  DEB(printf ("i2c_wait: MAL\n"));
	  return -1;
	}

      if (!(csr & MPC85xx_I2CSR_MCF))
	{
	  DEB(printf ("i2c_wait: unfinished\n"));
	  return -1;
	}

      if (write == I2C_WRITE && (csr & MPC85xx_I2CSR_RXAK))
	{
	  DEB(printf ("i2c_wait: No RXACK\n"));
	  return -1;
	}

      return 0;
    } while (get_timer (timeval) < TIMEOUT);

  DEB(printf ("i2c_wait: timed out\n"));
  return -1;
}

static __inline__ int
i2c_write_addr (u8 dev, u8 dir, int rsta)
{
  writel (MPC85xx_I2CCR_MEN | MPC85xx_I2CCR_MSTA | MPC85xx_I2CCR_MTX |
	  (rsta?MPC85xx_I2CCR_RSTA:0), I2CCCR);

  writel ((dev << 1) | dir, I2CCDR);

  if (i2c_wait (I2C_WRITE) < 0)
    return 0;

  return 1;
}

static __inline__ int
__i2c_write (u8 *data, int length)
{
  int i;

  writel (MPC85xx_I2CCR_MEN | MPC85xx_I2CCR_MSTA | MPC85xx_I2CCR_MTX, I2CCCR);

  for (i=0; i < length; i++)
    {
      writel (data[i], I2CCDR);

      if (i2c_wait (I2C_WRITE) < 0)
	break;
    }

  return i;
}

static __inline__ int
__i2c_read (u8 *data, int length)
{
  int i;

  writel (MPC85xx_I2CCR_MEN | MPC85xx_I2CCR_MSTA |
	  ((length == 1) ? MPC85xx_I2CCR_TXAK : 0), I2CCCR);

  /* dummy read */
  readl (I2CCDR);

  for (i=0; i < length; i++)
    {
      if (i2c_wait (I2C_READ) < 0)
	break;

      /* Generate ack on last next to last byte */
      if (i == length - 2)
	writel (MPC85xx_I2CCR_MEN | MPC85xx_I2CCR_MSTA |
		MPC85xx_I2CCR_TXAK, I2CCCR);

      /* Generate stop on last byte */
      if (i == length - 1)
	writel (MPC85xx_I2CCR_MEN | MPC85xx_I2CCR_TXAK, I2CCCR);

      data[i] = readl (I2CCDR);
    }

  return i;
}

int
i2c_read (u8 dev, uint addr, int alen, u8 *data, int length)
{
  int i = 0;
  u8 *a = (u8*)&addr;

  if (i2c_wait4bus () < 0)
    goto exit;

  if (i2c_write_addr (dev, I2C_WRITE, 0) == 0)
    goto exit;

  if (__i2c_write (&a[4 - alen], alen) != alen)
    goto exit;

  if (i2c_write_addr (dev, I2C_READ, 1) == 0)
    goto exit;

  i = __i2c_read (data, length);

 exit:
  writel (MPC85xx_I2CCR_MEN, I2CCCR);

  return !(i == length);
}

int
i2c_write (u8 dev, uint addr, int alen, u8 *data, int length)
{
  int i = 0;
  u8 *a = (u8*)&addr;

  if (i2c_wait4bus () < 0)
    goto exit;

  if (i2c_write_addr (dev, I2C_WRITE, 0) == 0)
    goto exit;

  if (__i2c_write (&a[4 - alen], alen) != alen)
    goto exit;

  i = __i2c_write (data, length);

 exit:
  writel (MPC85xx_I2CCR_MEN, I2CCCR);

  return !(i == length);
}

int i2c_probe (uchar chip)
{
	int tmp;

	/*
	 * Try to read the first location of the chip.  The underlying
	 * driver doesn't appear to support sending just the chip address
	 * and looking for an <ACK> back.
	 */
	udelay(10000);
	return i2c_read (chip, 0, 1, (char *)&tmp, 1);
}

uchar i2c_reg_read (uchar i2c_addr, uchar reg)
{
	char buf[1];

	i2c_read (i2c_addr, reg, 1, buf, 1);

	return (buf[0]);
}

void i2c_reg_write (uchar i2c_addr, uchar reg, uchar val)
{
	i2c_write (i2c_addr, reg, 1, &val, 1);
}

#endif /* CONFIG_HARD_I2C */