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/*
* linux/drivers/acorn/char/i2c.c
*
* Copyright (C) 2000 Russell King
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* ARM IOC/IOMD i2c driver.
*
* On Acorn machines, the following i2c devices are on the bus:
* - PCF8583 real time clock & static RAM
*/
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/i2c.h>
#include <linux/i2c-algo-bit.h>
#include <asm/hardware.h>
#include <asm/io.h>
#include <asm/hardware/ioc.h>
#include <asm/system.h>
#include "pcf8583.h"
extern unsigned long
mktime(unsigned int year, unsigned int mon, unsigned int day,
unsigned int hour, unsigned int min, unsigned int sec);
extern int (*set_rtc)(void);
static struct i2c_client *rtc_client;
static inline int rtc_command(int cmd, void *data)
{
int ret = -EIO;
if (rtc_client)
ret = rtc_client->driver->command(rtc_client, cmd, data);
return ret;
}
/*
* Read the current RTC time and date, and update xtime.
*/
static void get_rtc_time(void)
{
unsigned char ctrl;
unsigned char year;
struct rtc_tm rtctm;
struct mem rtcmem = { 0xc0, 1, &year };
/*
* Ensure that the RTC is running.
*/
rtc_command(RTC_GETCTRL, &ctrl);
if (ctrl & 0xc0) {
unsigned char new_ctrl;
new_ctrl = ctrl & ~0xc0;
printk("RTC: resetting control %02X -> %02X\n",
ctrl, new_ctrl);
rtc_command(RTC_SETCTRL, &new_ctrl);
}
/*
* Acorn machines store the year in
* the static RAM at location 192.
*/
if (rtc_command(MEM_READ, &rtcmem))
return;
if (rtc_command(RTC_GETDATETIME, &rtctm))
return;
if (year < 70)
year += 100;
xtime.tv_usec = rtctm.cs * 10000;
xtime.tv_sec = mktime(1900 + year, rtctm.mon, rtctm.mday,
rtctm.hours, rtctm.mins, rtctm.secs);
}
/*
* Set the RTC time only. Note that
* we do not touch the date.
*/
static int set_rtc_time(void)
{
struct rtc_tm new_rtctm, old_rtctm;
unsigned long nowtime = xtime.tv_sec;
if (rtc_command(RTC_GETDATETIME, &old_rtctm))
return 0;
new_rtctm.cs = xtime.tv_usec / 10000;
new_rtctm.secs = nowtime % 60; nowtime /= 60;
new_rtctm.mins = nowtime % 60; nowtime /= 60;
new_rtctm.hours = nowtime % 24;
/*
* avoid writing when we're going to change the day
* of the month. We will retry in the next minute.
* This basically means that if the RTC must not drift
* by more than 1 minute in 11 minutes.
*
* [ rtc: 1/1/2000 23:58:00, real 2/1/2000 00:01:00,
* rtc gets set to 1/1/2000 00:01:00 ]
*/
if ((old_rtctm.hours == 23 && old_rtctm.mins == 59) ||
(new_rtctm.hours == 23 && new_rtctm.mins == 59))
return 1;
return rtc_command(RTC_SETTIME, &new_rtctm);
}
#define FORCE_ONES 0xdc
#define SCL 0x02
#define SDA 0x01
/*
* We must preserve all non-i2c output bits in IOC_CONTROL.
* Note also that we need to preserve the value of SCL and
* SDA outputs as well (which may be different from the
* values read back from IOC_CONTROL).
*/
static u_int force_ones;
static void ioc_setscl(void *data, int state)
{
u_int ioc_control = ioc_readb(IOC_CONTROL) & ~(SCL | SDA);
u_int ones = force_ones;
if (state)
ones |= SCL;
else
ones &= ~SCL;
force_ones = ones;
ioc_writeb(ioc_control | ones, IOC_CONTROL);
}
static void ioc_setsda(void *data, int state)
{
u_int ioc_control = ioc_readb(IOC_CONTROL) & ~(SCL | SDA);
u_int ones = force_ones;
if (state)
ones |= SDA;
else
ones &= ~SDA;
force_ones = ones;
ioc_writeb(ioc_control | ones, IOC_CONTROL);
}
static int ioc_getscl(void *data)
{
return (ioc_readb(IOC_CONTROL) & SCL) != 0;
}
static int ioc_getsda(void *data)
{
return (ioc_readb(IOC_CONTROL) & SDA) != 0;
}
static struct i2c_algo_bit_data ioc_data = {
setsda: ioc_setsda,
setscl: ioc_setscl,
getsda: ioc_getsda,
getscl: ioc_getscl,
udelay: 80,
mdelay: 80,
timeout: 100
};
static int ioc_client_reg(struct i2c_client *client)
{
if (client->id == I2C_DRIVERID_PCF8583 &&
client->addr == 0x50) {
rtc_client = client;
get_rtc_time();
set_rtc = set_rtc_time;
}
return 0;
}
static int ioc_client_unreg(struct i2c_client *client)
{
if (client == rtc_client) {
set_rtc = NULL;
rtc_client = NULL;
}
return 0;
}
static struct i2c_adapter ioc_ops = {
name: "IOC/IOMD",
id: I2C_HW_B_IOC,
algo_data: &ioc_data,
client_register: ioc_client_reg,
client_unregister: ioc_client_unreg
};
static int __init i2c_ioc_init(void)
{
force_ones = FORCE_ONES | SCL | SDA;
return i2c_bit_add_bus(&ioc_ops);
}
__initcall(i2c_ioc_init);
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