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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 <linux/errno.h>
#include <asm/system.h>
#include <asm/hardware.h>
#include <asm/io.h>
#include <asm/ioc.h>
#define FORCE_ONES 0xdc
/*
* 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(100); /* was 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(10, IOC_T1LTCHL); /* was 4 */
outb(0, IOC_T1LTCHH);
outb(0, IOC_T1GO);
while ((inb(IOC_IRQSTATA) & (1<<6)) == 0);
restore_flags(flags);
}
}
#define IIC_INIT() dat = (inb(IOC_CONTROL) | FORCE_ONES) & ~3
#define IIC_SET_DAT outb(dat|=1, IOC_CONTROL);
#define IIC_CLR_DAT outb(dat&=~1, IOC_CONTROL);
#define IIC_SET_CLK outb(dat|=2, IOC_CONTROL);
#define IIC_CLR_CLK outb(dat&=~2, IOC_CONTROL);
#define IIC_DELAY iic_delay();
#define IIC_READ_DATA() (inb(IOC_CONTROL) & 1)
static inline void iic_set_lines(int clk, int dat)
{
int old;
old = inb(IOC_CONTROL) | FORCE_ONES;
old &= ~3;
if (clk)
old |= 2;
if (dat)
old |= 1;
outb(old, IOC_CONTROL);
iic_delay();
}
static inline unsigned int iic_read_data(void)
{
return inb(IOC_CONTROL) & 1;
}
/*
* C: ==~~_
* D: =~~__
*/
static inline void iic_start(void)
{
unsigned int dat;
IIC_INIT();
IIC_SET_DAT
IIC_DELAY
IIC_SET_CLK
IIC_DELAY
IIC_CLR_DAT
IIC_DELAY
IIC_CLR_CLK
IIC_DELAY
}
/*
* C: __~~
* D: =__~
*/
static inline void iic_stop(void)
{
unsigned int dat;
IIC_INIT();
IIC_CLR_DAT
IIC_DELAY
IIC_SET_CLK
IIC_DELAY
IIC_SET_DAT
IIC_DELAY
}
/*
* C: __~_
* D: =___
*/
static inline void iic_acknowledge(void)
{
unsigned int dat;
IIC_INIT();
IIC_CLR_DAT
IIC_DELAY
IIC_SET_CLK
IIC_DELAY
IIC_CLR_CLK
IIC_DELAY
}
/*
* C: __~_
* D: =~H~
*/
static inline int iic_is_acknowledged(void)
{
unsigned int dat, ack_bit;
IIC_INIT();
IIC_SET_DAT
IIC_DELAY
IIC_SET_CLK
IIC_DELAY
ack_bit = IIC_READ_DATA();
IIC_CLR_CLK
IIC_DELAY
return ack_bit == 0;
}
/*
* C: _~__~__~__~__~__~__~__~_
* D: =DDXDDXDDXDDXDDXDDXDDXDD
*/
static void iic_sendbyte(unsigned int b)
{
unsigned int dat, i;
IIC_INIT();
for (i = 0; i < 8; i++) {
if (b & 128)
IIC_SET_DAT
else
IIC_CLR_DAT
IIC_DELAY
IIC_SET_CLK
IIC_DELAY
IIC_CLR_CLK
IIC_DELAY
b <<= 1;
}
}
/*
* C: __~_~_~_~_~_~_~_~_
* D: =~HHHHHHHHHHHHHHHH
*/
static unsigned char iic_recvbyte(void)
{
unsigned int dat, i, in;
IIC_INIT();
IIC_SET_DAT
IIC_DELAY
in = 0;
for (i = 0; i < 8; i++) {
IIC_SET_CLK
IIC_DELAY
in = (in << 1) | IIC_READ_DATA();
IIC_CLR_CLK
IIC_DELAY
}
return in;
}
int iic_control (unsigned char addr, unsigned char loc, unsigned char *buf, int len)
{
int i, err = -EIO;
iic_start();
iic_sendbyte(addr & 0xfe);
if (!iic_is_acknowledged())
goto error;
iic_sendbyte(loc);
if (!iic_is_acknowledged())
goto error;
if (addr & 1) {
iic_stop();
iic_start();
iic_sendbyte(addr|1);
if (!iic_is_acknowledged())
goto error;
for (i = 0; i < len - 1; i++) {
buf[i] = iic_recvbyte();
iic_acknowledge();
}
buf[i] = iic_recvbyte();
} else {
for (i = 0; i < len; i++) {
iic_sendbyte(buf[i]);
if (!iic_is_acknowledged())
goto error;
}
}
err = 0;
error:
iic_stop();
return err;
}
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