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/*
* linux/arch/arm/kernel/iic.c
*
* Copyright (C) 1995, 1996 Russell King
*
* IIC is used to get the current time from the CMOS rtc.
*/
#include <linux/delay.h>
#include <asm/system.h>
#include <asm/io.h>
#include <asm/hardware.h>
/*
* if delay loop has been calibrated then us that,
* else use IOC timer 1.
*/
static void iic_delay (void)
{
extern unsigned long loops_per_sec;
if (loops_per_sec != (1 << 12)) {
udelay(10);
return;
} else {
unsigned long flags;
save_flags_cli(flags);
outb(254, IOC_T1LTCHL);
outb(255, IOC_T1LTCHH);
outb(0, IOC_T1GO);
outb(1<<6, IOC_IRQCLRA); /* clear T1 irq */
outb(4, IOC_T1LTCHL);
outb(0, IOC_T1LTCHH);
outb(0, IOC_T1GO);
while ((inb(IOC_IRQSTATA) & (1<<6)) == 0);
restore_flags(flags);
}
}
static inline void iic_start (void)
{
unsigned char out;
out = inb(IOC_CONTROL) | 0xc2;
outb(out, IOC_CONTROL);
iic_delay();
outb(out ^ 1, IOC_CONTROL);
iic_delay();
}
static inline void iic_stop (void)
{
unsigned char out;
out = inb(IOC_CONTROL) | 0xc3;
iic_delay();
outb(out ^ 1, IOC_CONTROL);
iic_delay();
outb(out, IOC_CONTROL);
}
static int iic_sendbyte (unsigned char b)
{
unsigned char out, in;
int i;
out = (inb(IOC_CONTROL) & 0xfc) | 0xc0;
outb(out, IOC_CONTROL);
for (i = 7; i >= 0; i--) {
unsigned char c;
c = out | ((b & (1 << i)) ? 1 : 0);
outb(c, IOC_CONTROL);
iic_delay();
outb(c | 2, IOC_CONTROL);
iic_delay();
outb(c, IOC_CONTROL);
}
outb(out | 1, IOC_CONTROL);
iic_delay();
outb(out | 3, IOC_CONTROL);
iic_delay();
in = inb(IOC_CONTROL) & 1;
outb(out | 1, IOC_CONTROL);
iic_delay();
outb(out, IOC_CONTROL);
iic_delay();
if(in) {
printk("No acknowledge from RTC\n");
return 1;
} else
return 0;
}
static unsigned char iic_recvbyte (void)
{
unsigned char out, in;
int i;
out = (inb(IOC_CONTROL) & 0xfc) | 0xc0;
outb(out, IOC_CONTROL);
in = 0;
for (i = 7; i >= 0; i--) {
outb(out | 1, IOC_CONTROL);
iic_delay();
outb(out | 3, IOC_CONTROL);
iic_delay();
in = (in << 1) | (inb(IOC_CONTROL) & 1);
outb(out | 1, IOC_CONTROL);
iic_delay();
}
outb(out, IOC_CONTROL);
iic_delay();
outb(out | 2, IOC_CONTROL);
iic_delay();
return in;
}
void iic_control (unsigned char addr, unsigned char loc, unsigned char *buf, int len)
{
iic_start();
if (iic_sendbyte(addr & 0xfe))
goto error;
if (iic_sendbyte(loc))
goto error;
if (addr & 1) {
int i;
for (i = 0; i < len; i++)
if (iic_sendbyte (buf[i]))
break;
} else {
int i;
iic_stop();
iic_start();
iic_sendbyte(addr|1);
for (i = 0; i < len; i++)
buf[i] = iic_recvbyte ();
}
error:
iic_stop();
}
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