// SPDX-License-Identifier: GPL-2.0-only
/*
* drivers/rtc/rtc-pcf8583.c
*
* Copyright (C) 2000 Russell King
* Copyright (C) 2008 Wolfram Sang & Juergen Beisert, Pengutronix
*
* Driver for PCF8583 RTC & RAM chip
*
* Converted to the generic RTC susbsystem by G. Liakhovetski (2006)
*/
#include <linux/module.h>
#include <linux/i2c.h>
#include <linux/slab.h>
#include <linux/rtc.h>
#include <linux/init.h>
#include <linux/err.h>
#include <linux/errno.h>
#include <linux/bcd.h>
struct rtc_mem {
unsigned int loc;
unsigned int nr;
unsigned char *data;
};
struct pcf8583 {
struct rtc_device *rtc;
unsigned char ctrl;
};
#define CTRL_STOP 0x80
#define CTRL_HOLD 0x40
#define CTRL_32KHZ 0x00
#define CTRL_MASK 0x08
#define CTRL_ALARMEN 0x04
#define CTRL_ALARM 0x02
#define CTRL_TIMER 0x01
static struct i2c_driver pcf8583_driver;
#define get_ctrl(x) ((struct pcf8583 *)i2c_get_clientdata(x))->ctrl
#define set_ctrl(x, v) get_ctrl(x) = v
#define CMOS_YEAR (64 + 128)
#define CMOS_CHECKSUM (63)
static int pcf8583_get_datetime(struct i2c_client *client, struct rtc_time *dt)
{
unsigned char buf[8], addr[1] = { 1 };
struct i2c_msg msgs[2] = {
{
.addr = client->addr,
.flags = 0,
.len = 1,
.buf = addr,
}, {
.addr = client->addr,
.flags = I2C_M_RD,
.len = 6,
.buf = buf,
}
};
int ret;
memset(buf, 0, sizeof(buf));
ret = i2c_transfer(client->adapter, msgs, 2);
if (ret == 2) {
dt->tm_year = buf[4] >> 6;
dt->tm_wday = buf[5] >> 5;
buf[4] &= 0x3f;
buf[5] &= 0x1f;
dt->tm_sec = bcd2bin(buf[1]);
dt->tm_min = bcd2bin(buf[2]);
dt->tm_hour = bcd2bin(buf[3]);
dt->tm_mday = bcd2bin(buf[4]);
dt->tm_mon = bcd2bin(buf[5]) - 1;
}
return ret == 2 ? 0 : -EIO;
}
static int pcf8583_set_datetime(struct i2c_client *client, struct rtc_time *dt, int datetoo)
{
unsigned char buf[8];
int ret, len = 6;
buf[0] = 0;
buf[1] = get_ctrl(client) | 0x80;
buf[2] = 0;
buf[3] = bin2bcd(dt->tm_sec);
buf[4] = bin2bcd(dt->tm_min);
buf[5] = bin2bcd(dt->tm_hour);
if (datetoo) {
len = 8;
buf[6] = bin2bcd(dt->tm_mday) | (dt->tm_year << 6);
buf[7] = bin2bcd(dt->tm_mon + 1) | (dt->tm_wday << 5);
}
ret = i2c_master_send(client, (char *)buf, len);
if (ret != len)
return -EIO;
buf[1] = get_ctrl(client);
ret = i2c_master_send(client, (char *)buf, 2);
return ret == 2 ? 0 : -EIO;
}
static int pcf8583_get_ctrl(struct i2c_client *client, unsigned char *ctrl)
{
*ctrl = get_ctrl(client);
return 0;
}
static int pcf8583_set_ctrl(struct i2c_client *client, unsigned char *ctrl)
{
unsigned char buf[2];
buf[0] = 0;
buf[1] = *ctrl;
set_ctrl(client, *ctrl);
return i2c_master_send(client, (char *)buf, 2);
}
static int pcf8583_read_mem(struct i2c_client *client, struct rtc_mem *mem)
{
unsigned char addr[1];
struct i2c_msg msgs[2] = {
{
.addr = client->addr,
.flags = 0,
.len = 1,
.buf = addr,
}, {
.addr = client->addr,
.flags = I2C_M_RD,
.len = mem->nr,
.buf = mem->data,
}
};
if (mem->loc < 8)
return -EINVAL;
addr[0] = mem->loc;
return i2c_transfer(client->adapter, msgs, 2) == 2 ? 0 : -EIO;
}
static int pcf8583_write_mem(struct i2c_client *client, struct rtc_mem *mem)
{
unsigned char buf[9];
int ret;
if (mem->loc < 8 || mem->nr > 8)
return -EINVAL;
buf[0] = mem->loc;
memcpy(buf + 1, mem->data, mem->nr);
ret = i2c_master_send(client, buf, mem->nr + 1);
return ret == mem->nr + 1 ? 0 : -EIO;
}
static int pcf8583_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
struct i2c_client *client = to_i2c_client(dev);
unsigned char ctrl, year[2];
struct rtc_mem mem = {
.loc = CMOS_YEAR,
.nr = sizeof(year),
.data = year
};
int real_year, year_offset, err;
/*
* Ensure that the RTC is running.
*/
pcf8583_get_ctrl(client, &ctrl);
if (ctrl & (CTRL_STOP | CTRL_HOLD)) {
unsigned char new_ctrl = ctrl & ~(CTRL_STOP | CTRL_HOLD);
dev_warn(dev, "resetting control %02x -> %02x\n",
ctrl, new_ctrl);
err = pcf8583_set_ctrl(client, &new_ctrl);
if (err < 0)
return err;
}
if (pcf8583_get_datetime(client, tm) ||
pcf8583_read_mem(client, &mem))
return -EIO;
real_year = year[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 = tm->tm_year - (real_year & 3);
if (year_offset < 0)
/*
* RTC year wrapped. Adjust it appropriately.
*/
year_offset += 4;
tm->tm_year = (real_year + year_offset + year[1] * 100) - 1900;
return 0;
}
static int pcf8583_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
struct i2c_client *client = to_i2c_client(dev);
unsigned char year[2], chk;
struct rtc_mem cmos_year = {
.loc = CMOS_YEAR,
.nr = sizeof(year),
.data = year
};
struct rtc_mem cmos_check = {
.loc = CMOS_CHECKSUM,
.nr = 1,
.data = &chk
};
unsigned int proper_year = tm->tm_year + 1900;
int ret;
/*
* The RTC's own 2-bit year must reflect the least
* significant two bits of the CMOS year.
*/
ret = pcf8583_set_datetime(client, tm, 1);
if (ret)
return ret;
ret = pcf8583_read_mem(client, &cmos_check);
if (ret)
return ret;
ret = pcf8583_read_mem(client, &cmos_year);
if (ret)
return ret;
chk -= year[1] + year[0];
year[1] = proper_year / 100;
year[0] = proper_year % 100;
chk += year[1] + year[0];
ret = pcf8583_write_mem(client, &cmos_year);
if (ret)
return ret;
ret = pcf8583_write_mem(client, &cmos_check);
return ret;
}
static const struct rtc_class_ops pcf8583_rtc_ops = {
.read_time = pcf8583_rtc_read_time,
.set_time = pcf8583_rtc_set_time,
};
static int pcf8583_probe(struct i2c_client *client)
{
struct pcf8583 *pcf8583;
if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
return -ENODEV;
pcf8583 = devm_kzalloc(&client->dev, sizeof(struct pcf8583),
GFP_KERNEL);
if (!pcf8583)
return -ENOMEM;
i2c_set_clientdata(client, pcf8583);
pcf8583->rtc = devm_rtc_device_register(&client->dev,
pcf8583_driver.driver.name,
&pcf8583_rtc_ops, THIS_MODULE);
return PTR_ERR_OR_ZERO(pcf8583->rtc);
}
static const struct i2c_device_id pcf8583_id[] = {
{ "pcf8583" },
{ }
};
MODULE_DEVICE_TABLE(i2c, pcf8583_id);
static struct i2c_driver pcf8583_driver = {
.driver = {
.name = "pcf8583",
},
.probe = pcf8583_probe,
.id_table = pcf8583_id,
};
module_i2c_driver(pcf8583_driver);
MODULE_AUTHOR("Russell King");
MODULE_DESCRIPTION("PCF8583 I2C RTC driver");
MODULE_LICENSE("GPL");
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