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#include "config.h"
#include "cpu.h"
#include "kernel.h"
#include "system.h"
#include "logf.h"
#include "debug.h"
#include "string.h"
#define SLAVE_ADDRESS 0xCC
#define USE_ASM
/* This I2C driver tristates the outputs instead of driving logic high's */
#define SDA (GPHDAT & (1 << 9))
#define SDA_LO_OUT (GPHCON |= (1 << 18));(GPHDAT &= ~(1 << 9));
#define SDA_HI_IN (GPHCON &= ~(3 << 18))
#define SCL (GPHDAT & (1 << 10))
#define SCL_LO_OUT (GPHCON |= (1 << 20));(GPHDAT &= ~(1 << 10));
#define SCL_HI_IN (GPHCON &= ~(3 << 20));while(!SCL);
/* The SC606 can clock at 400KHz:
* Clock period high is 600nS and low is 1300nS
* The high and low times are different enough to need different timings
* cycles delayed = 2 + 4 * loops
* 100MHz = 10nS per cycle: LO:1300nS=130:33 HI:600nS=60:15
* 300MHz = 3.33nS per cycle:
* LO:1300nS=394:99
* HI:600nS=182:21
* MID(50/50):950(1900/2)ns=288:72
*/
#ifdef USE_ASM
#define DELAY_LO 99
#define DELAY_MID 72
#define DELAY_HI 46
/* This delay loop takes 4 cycles/loop to execute plus 2 for setup */
#define DELAY(dly) \
asm volatile( "mov r0,%0 \n" \
"1: \n" \
"subs r0,r0,#1 \n" \
"bhi 1b \n" \
: : "r"((dly)) : "r0" );
#else
#define DELAY_LO 51
#define DELAY_MID 35
#define DELAY_HI 21
#define DELAY(dly) do{int x;for(x=(dly);x;x--);} while (0)
#endif
static void sc606_i2c_start(void)
{
SDA_HI_IN;
SCL_HI_IN;
DELAY(DELAY_MID);
SDA_LO_OUT;
DELAY(DELAY_MID);
SCL_LO_OUT;
}
static void sc606_i2c_stop(void)
{
SDA_LO_OUT;
SCL_HI_IN;
DELAY(DELAY_HI);
SDA_HI_IN;
}
static void sc606_i2c_ack(void)
{
SDA_HI_IN;
SCL_HI_IN;
DELAY(DELAY_HI);
SCL_LO_OUT;
}
static bool sc606_i2c_getack(void)
{
bool ret;
SDA_HI_IN;
DELAY(DELAY_MID);
SCL_HI_IN;
ret = !SDA;
SCL_LO_OUT;
DELAY(DELAY_LO);
return ret;
}
static void sc606_i2c_outb(unsigned char byte)
{
int i;
/* clock out each bit, MSB first */
for ( i=0x80; i; i>>=1 )
{
if ( i & byte )
SDA_HI_IN;
else
SDA_LO_OUT;
DELAY(DELAY_MID);
SCL_HI_IN;
DELAY(DELAY_HI);
SCL_LO_OUT;
}
}
static unsigned char sc606_i2c_inb(void)
{
int i;
unsigned char byte = 0;
/* clock in each bit, MSB first */
SDA_HI_IN;
for ( i=0x80; i; i>>=1 )
{
SCL_HI_IN;
DELAY(DELAY_HI);
if ( SDA )
byte |= i;
SCL_LO_OUT;
DELAY(DELAY_LO);
}
sc606_i2c_ack();
return byte;
}
/* returns number of acks that were bad */
int sc606_write(unsigned char reg, unsigned char data)
{
int x;
sc606_i2c_start();
sc606_i2c_outb(SLAVE_ADDRESS);
x = sc606_i2c_getack();
sc606_i2c_outb(reg);
x += sc606_i2c_getack();
sc606_i2c_start();
sc606_i2c_outb(SLAVE_ADDRESS);
x += sc606_i2c_getack();
sc606_i2c_outb(data);
x += sc606_i2c_getack();
sc606_i2c_stop();
return x;
}
int sc606_read(unsigned char reg, unsigned char* data)
{
int x;
sc606_i2c_start();
sc606_i2c_outb(SLAVE_ADDRESS);
x = sc606_i2c_getack();
sc606_i2c_outb(reg);
x += sc606_i2c_getack();
sc606_i2c_start();
sc606_i2c_outb(SLAVE_ADDRESS | 1);
x += sc606_i2c_getack();
*data = sc606_i2c_inb();
sc606_i2c_stop();
return x;
}
void sc606_init(void)
{
volatile int i;
/* Set GPB2 (EN) to 1 */
GPBCON = (GPBCON & ~(3<<4)) | 1<<4;
/* Turn enable line on */
GPBDAT |= 1<<2;
/* OFF GPBDAT &= ~(1 << 2); */
/* About 400us - needs 350us */
for (i = 200; i; i--)
DELAY(DELAY_LO);
/* Set GPH9 (SDA) and GPH10 (SCL) to 1 */
GPHUP &= ~(3<<9);
SCL_HI_IN;
SDA_HI_IN;
}
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