rockbox/firmware/drivers/pcf50606.c

/***************************************************************************
 *             __________               __   ___.
 *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
 *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
 *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
 *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
 *                     \/            \/     \/    \/            \/
 * $Id$
 *
 * Copyright (C) 2005 by Linus Nielsen Feltzing
 *
 * All files in this archive are subject to the GNU General Public License.
 * See the file COPYING in the source tree root for full license agreement.
 *
 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
 * KIND, either express or implied.
 *
 ****************************************************************************/
#include "config.h"
#include "cpu.h"
#include <stdbool.h>
#include "kernel.h"
#include "system.h"
#include "hwcompat.h"
#include "logf.h"
#include "string.h"

/* TODO: merge all bit-banged I2C into a generic I2C driver */


#define SDA_LO     and_l(~0x00002000, &GPIO1_OUT)
#define SDA_HI      or_l( 0x00002000, &GPIO1_OUT)
#define SDA_INPUT  and_l(~0x00002000, &GPIO1_ENABLE)
#define SDA_OUTPUT  or_l( 0x00002000, &GPIO1_ENABLE)
#define SDA             ( 0x00002000 & GPIO1_READ)

/* SCL is GPIO, 3 */
#define SCL_INPUT  and_l(~0x00001000, &GPIO_ENABLE)
#define SCL_OUTPUT  or_l( 0x00001000, &GPIO_ENABLE)
#define SCL_LO     and_l(~0x00001000, &GPIO_OUT)
#define SCL_HI      or_l( 0x00001000, &GPIO_OUT)
#define SCL             ( 0x00001000 & GPIO_READ)

/* delay loop to achieve 400kHz at 120MHz CPU frequency */
#define DELAY    do { int _x; for(_x=0;_x<22;_x++);} while(0)


static void pcf50606_i2c_start(void)
{
    SDA_OUTPUT;
    SCL_OUTPUT;
    SDA_HI;
    SCL_HI;
    DELAY;
    SDA_LO;
    DELAY;
    SCL_LO;
}

static void pcf50606_i2c_stop(void)
{
   SDA_LO;
   SCL_HI;
   DELAY;
   SDA_HI;
}


static void pcf50606_i2c_ack(bool ack)
{
    /* Here's the deal. The slave is slow, and sometimes needs to wait
       before it can receive the acknowledge. Therefore it forces the clock
       low until it is ready. We need to poll the clock line until it goes
       high before we release the ack.

       In their infinite wisdom, iriver didn't pull up the SCL line, so
       we have to drive the SCL high repeatedly to simulate a pullup. */
    
    SCL_LO;      /* Set the clock low */
    if(ack)
        SDA_LO;
    else
        SDA_HI;
    
    SCL_INPUT;   /* Set the clock to input */
    while(!SCL)  /* and wait for the slave to release it */
    {
        SCL_OUTPUT;  /* Set the clock to output */
        SCL_HI;
        SCL_INPUT;   /* Set the clock to input */
        DELAY;
    }

    DELAY;
    SCL_OUTPUT;
    SCL_LO;
}

static int pcf50606_i2c_getack(void)
{
    int ret = 1;

    /* Here's the deal. The slave is slow, and sometimes needs to wait
       before it can send the acknowledge. Therefore it forces the clock
       low until it is ready. We need to poll the clock line until it goes
       high before we read the ack.

       In their infinite wisdom, iriver didn't pull up the SCL line, so
       we have to drive the SCL high repeatedly to simulate a pullup. */

    SDA_INPUT;   /* And set to input */
    SCL_INPUT;   /* Set the clock to input */
    while(!SCL)  /* and wait for the slave to release it */
    {
        SCL_OUTPUT;  /* Set the clock to output */
        SCL_HI;
        SCL_INPUT;   /* Set the clock to input */
        DELAY;
    }

    if (SDA)
        /* ack failed */
        ret = 0;
    
    SCL_OUTPUT;
    SCL_LO;
    SDA_HI;
    SDA_OUTPUT;

    return ret;
}

static void pcf50606_i2c_outb(unsigned char byte)
{
   int i;

   /* clock out each bit, MSB first */
   for ( i=0x80; i; i>>=1 ) {
      if ( i & byte )
      {
         SDA_HI;
      }
      else
      {
         SDA_LO;
      }
      DELAY;
      SCL_HI;
      DELAY;
      SCL_LO;
   }

   SDA_HI;
}

static unsigned char pcf50606_i2c_inb(bool ack)
{
   int i;
   unsigned char byte = 0;

   /* clock in each bit, MSB first */
   for ( i=0x80; i; i>>=1 ) {
       SDA_INPUT;   /* And set to input */
       SCL_HI;
       DELAY;
       if ( SDA )
           byte |= i;
       SCL_LO;
       DELAY;
       SDA_OUTPUT;
   }

   pcf50606_i2c_ack(ack);
   
   return byte;
}

int pcf50606_i2c_write(int address, const unsigned char* buf, int count)
{
    int i,x=0;

    pcf50606_i2c_start();
    pcf50606_i2c_outb(address & 0xfe);
    if (pcf50606_i2c_getack())
    {
        for (i=0; i<count; i++)
        {
            pcf50606_i2c_outb(buf[i]);
            if (!pcf50606_i2c_getack())
            {
                x=-2;
                break;
            }
        }
    }
    else
    {
        logf("pcf50606_i2c_write() - no ack\n");
        x=-1;
    }
    return x;
}

int pcf50606_read(int address, unsigned char* buf, int count)
{
    int i=0;
    int ret = 0;
    unsigned char obuf[1];

    obuf[0] = address;

    /* send read command */
    if (pcf50606_i2c_write(0x10, obuf, 1) >= 0)
    {
        pcf50606_i2c_start();
        pcf50606_i2c_outb(0x11);
        if (pcf50606_i2c_getack())
        {
            for(i = 0;i < count-1;i++)
                buf[i] = pcf50606_i2c_inb(true);
            
            buf[i] = pcf50606_i2c_inb(false);
        }
        else
        {
            ret = -1;
        }
    }

    pcf50606_i2c_stop();

    return ret;
}

int pcf50606_write(int address, const unsigned char* buf, int count)
{
    unsigned char obuf[1];
    int i;
    int ret = 0;

    obuf[0] = address;
    
    /* send write command */
    if (pcf50606_i2c_write(0x10, obuf, 1) >= 0)
    {
        for (i=0; i<count; i++)
        {
            pcf50606_i2c_outb(buf[i]);
            if (!pcf50606_i2c_getack())
            {
                ret = -2;
                break;
            }
        }
    }
    else
    {
        ret = -1;
    }

    pcf50606_i2c_stop();
    return ret;
}

/* These voltages were determined by measuring the output of the PCF50606
   on a running H300, and verified by disassembling the original firmware */
static void set_voltages(void)
{
    static const unsigned char buf[5] =
        {
            0xf4,   /* IOREGC = 3.3V, ON in all states */
            0xef,   /* D1REGC = 2.4V, ON in all states */
            0x18,   /* D2REGC = 3.3V, OFF in all states */
            0xf0,   /* D3REGC = 2.5V, ON in all states */
            0xef,   /* LPREGC1 = 2.4V, ON in all states */
        };
    
    pcf50606_write(0x23, buf, 5);
}

void pcf50606_init(void)
{
    unsigned char c;
    
    /* Bit banged I2C */
    or_l(0x00002000, &GPIO1_OUT);
    or_l(0x00001000, &GPIO_OUT);
    or_l(0x00002000, &GPIO1_ENABLE);
    or_l(0x00001000, &GPIO_ENABLE);
    or_l(0x00002000, &GPIO1_FUNCTION);
    or_l(0x00001000, &GPIO_FUNCTION);

    set_voltages();

    /* Backlight PWM = 512Hz 50/50 */
    c = 0x13;
    pcf50606_write(0x35, &c, 1);
}