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linux-sg2042/drivers/acorn/char/i2c.c

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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/time.h>
#include <linux/miscdevice.h>
#include <linux/rtc.h>
#include <linux/i2c.h>
#include <linux/i2c-algo-bit.h>
#include <linux/fs.h>
#include <asm/hardware.h>
#include <asm/io.h>
#include <asm/hardware/ioc.h>
#include <asm/system.h>
#include <asm/uaccess.h>
#include "pcf8583.h"
extern int (*set_rtc)(void);
static struct i2c_client *rtc_client;
static const unsigned char days_in_mon[] =
{ 0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };
#define CMOS_CHECKSUM (63)
/*
* Acorn machines store the year in the static RAM at
* location 128.
*/
#define CMOS_YEAR (64 + 128)
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;
}
/*
* Update the century + year bytes in the CMOS RAM, ensuring
* that the check byte is correctly adjusted for the change.
*/
static int rtc_update_year(unsigned int new_year)
{
unsigned char yr[2], chk;
struct mem cmos_year = { CMOS_YEAR, sizeof(yr), yr };
struct mem cmos_check = { CMOS_CHECKSUM, 1, &chk };
int ret;
ret = rtc_command(MEM_READ, &cmos_check);
if (ret)
goto out;
ret = rtc_command(MEM_READ, &cmos_year);
if (ret)
goto out;
chk -= yr[1] + yr[0];
yr[1] = new_year / 100;
yr[0] = new_year % 100;
chk += yr[1] + yr[0];
ret = rtc_command(MEM_WRITE, &cmos_year);
if (ret == 0)
ret = rtc_command(MEM_WRITE, &cmos_check);
out:
return ret;
}
/*
* Read the current RTC time and date, and update xtime.
*/
static void get_rtc_time(struct rtc_tm *rtctm, unsigned int *year)
{
unsigned char ctrl, yr[2];
struct mem rtcmem = { CMOS_YEAR, sizeof(yr), yr };
int real_year, year_offset;
/*
* Ensure that the RTC is running.
*/
rtc_command(RTC_GETCTRL, &ctrl);
if (ctrl & 0xc0) {
unsigned char new_ctrl = ctrl & ~0xc0;
printk(KERN_WARNING "RTC: resetting control %02x -> %02x\n",
ctrl, new_ctrl);
rtc_command(RTC_SETCTRL, &new_ctrl);
}
if (rtc_command(RTC_GETDATETIME, rtctm) ||
rtc_command(MEM_READ, &rtcmem))
return;
real_year = yr[0];
/*
* The RTC year holds the LSB two bits of the current
* year, which should reflect the LSB two bits of the
* CMOS copy of the year. Any difference indicates
* that we have to correct the CMOS version.
*/
year_offset = rtctm->year_off - (real_year & 3);
if (year_offset < 0)
/*
* RTC year wrapped. Adjust it appropriately.
*/
year_offset += 4;
*year = real_year + year_offset + yr[1] * 100;
}
static int set_rtc_time(struct rtc_tm *rtctm, unsigned int year)
{
unsigned char leap;
int ret;
leap = (!(year % 4) && (year % 100)) || !(year % 400);
if (rtctm->mon > 12 || rtctm->mon == 0 || rtctm->mday == 0)
return -EINVAL;
if (rtctm->mday > (days_in_mon[rtctm->mon] + (rtctm->mon == 2 && leap)))
return -EINVAL;
if (rtctm->hours >= 24 || rtctm->mins >= 60 || rtctm->secs >= 60)
return -EINVAL;
/*
* The RTC's own 2-bit year must reflect the least
* significant two bits of the CMOS year.
*/
rtctm->year_off = (year % 100) & 3;
ret = rtc_command(RTC_SETDATETIME, rtctm);
if (ret == 0)
ret = rtc_update_year(year);
return ret;
}
/*
* Set the RTC time only. Note that
* we do not touch the date.
*/
static int k_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_nsec / 10000000;
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);
}
static int rtc_ioctl(struct inode *inode, struct file *file,
unsigned int cmd, unsigned long arg)
{
unsigned int year;
struct rtc_time rtctm;
struct rtc_tm rtc_raw;
switch (cmd) {
case RTC_ALM_READ:
case RTC_ALM_SET:
break;
case RTC_RD_TIME:
memset(&rtctm, 0, sizeof(struct rtc_time));
get_rtc_time(&rtc_raw, &year);
rtctm.tm_sec = rtc_raw.secs;
rtctm.tm_min = rtc_raw.mins;
rtctm.tm_hour = rtc_raw.hours;
rtctm.tm_mday = rtc_raw.mday;
rtctm.tm_mon = rtc_raw.mon - 1; /* month starts at 0 */
rtctm.tm_year = year - 1900; /* starts at 1900 */
return copy_to_user((void *)arg, &rtctm, sizeof(rtctm))
? -EFAULT : 0;
case RTC_SET_TIME:
if (!capable(CAP_SYS_TIME))
return -EACCES;
if (copy_from_user(&rtctm, (void *)arg, sizeof(rtctm)))
return -EFAULT;
rtc_raw.secs = rtctm.tm_sec;
rtc_raw.mins = rtctm.tm_min;
rtc_raw.hours = rtctm.tm_hour;
rtc_raw.mday = rtctm.tm_mday;
rtc_raw.mon = rtctm.tm_mon + 1;
year = rtctm.tm_year + 1900;
return set_rtc_time(&rtc_raw, year);
break;
case RTC_EPOCH_READ:
return put_user(1900, (unsigned long *)arg);
}
return -EINVAL;
}
static struct file_operations rtc_fops = {
.ioctl = rtc_ioctl,
};
static struct miscdevice rtc_dev = {
.minor = RTC_MINOR,
.name = "rtc",
.fops = &rtc_fops,
};
/* IOC / IOMD i2c driver */
#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->driver->id == I2C_DRIVERID_PCF8583 &&
client->addr == 0x50) {
struct rtc_tm rtctm;
unsigned int year;
struct timespec tv;
rtc_client = client;
get_rtc_time(&rtctm, &year);
tv.tv_nsec = rtctm.cs * 10000000;
tv.tv_sec = mktime(year, rtctm.mon, rtctm.mday,
rtctm.hours, rtctm.mins, rtctm.secs);
do_settimeofday(&tv);
set_rtc = k_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 = {
.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)
{
int ret;
force_ones = FORCE_ONES | SCL | SDA;
ret = i2c_bit_add_bus(&ioc_ops);
if (ret >= 0){
ret = misc_register(&rtc_dev);
if(ret < 0)
i2c_bit_del_bus(&ioc_ops);
}
return ret;
}
__initcall(i2c_ioc_init);
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