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// SPDX-License-Identifier: GPL-2.0
/*
* An I2C driver for the PCF85063 RTC
* Copyright 2014 Rose Technology
*
* Author: Søren Andersen <san@rosetechnology.dk>
* Maintainers: http://www.nslu2-linux.org/
*/
#include <linux/i2c.h>
#include <linux/bcd.h>
#include <linux/rtc.h>
#include <linux/module.h>
/*
* Information for this driver was pulled from the following datasheets.
*
* http://www.nxp.com/documents/data_sheet/PCF85063A.pdf
* http://www.nxp.com/documents/data_sheet/PCF85063TP.pdf
*
* PCF85063A -- Rev. 6 — 18 November 2015
* PCF85063TP -- Rev. 4 — 6 May 2015
*/
#define PCF85063_REG_CTRL1 0x00 /* status */
#define PCF85063_REG_CTRL1_CAP_SEL BIT(0)
#define PCF85063_REG_CTRL1_STOP BIT(5)
#define PCF85063_REG_SC 0x04 /* datetime */
#define PCF85063_REG_SC_OS 0x80
static int pcf85063_stop_clock(struct i2c_client *client, u8 *ctrl1)
{
int rc;
u8 reg;
rc = i2c_smbus_read_byte_data(client, PCF85063_REG_CTRL1);
if (rc < 0) {
dev_err(&client->dev, "Failing to stop the clock\n");
return -EIO;
}
/* stop the clock */
reg = rc | PCF85063_REG_CTRL1_STOP;
rc = i2c_smbus_write_byte_data(client, PCF85063_REG_CTRL1, reg);
if (rc < 0) {
dev_err(&client->dev, "Failing to stop the clock\n");
return -EIO;
}
*ctrl1 = reg;
return 0;
}
static int pcf85063_start_clock(struct i2c_client *client, u8 ctrl1)
{
int rc;
/* start the clock */
ctrl1 &= ~PCF85063_REG_CTRL1_STOP;
rc = i2c_smbus_write_byte_data(client, PCF85063_REG_CTRL1, ctrl1);
if (rc < 0) {
dev_err(&client->dev, "Failing to start the clock\n");
return -EIO;
}
return 0;
}
static int pcf85063_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
struct i2c_client *client = to_i2c_client(dev);
int rc;
u8 regs[7];
/*
* while reading, the time/date registers are blocked and not updated
* anymore until the access is finished. To not lose a second
* event, the access must be finished within one second. So, read all
* time/date registers in one turn.
*/
rc = i2c_smbus_read_i2c_block_data(client, PCF85063_REG_SC,
sizeof(regs), regs);
if (rc != sizeof(regs)) {
dev_err(&client->dev, "date/time register read error\n");
return -EIO;
}
/* if the clock has lost its power it makes no sense to use its time */
if (regs[0] & PCF85063_REG_SC_OS) {
dev_warn(&client->dev, "Power loss detected, invalid time\n");
return -EINVAL;
}
tm->tm_sec = bcd2bin(regs[0] & 0x7F);
tm->tm_min = bcd2bin(regs[1] & 0x7F);
tm->tm_hour = bcd2bin(regs[2] & 0x3F); /* rtc hr 0-23 */
tm->tm_mday = bcd2bin(regs[3] & 0x3F);
tm->tm_wday = regs[4] & 0x07;
tm->tm_mon = bcd2bin(regs[5] & 0x1F) - 1; /* rtc mn 1-12 */
tm->tm_year = bcd2bin(regs[6]);
tm->tm_year += 100;
return 0;
}
static int pcf85063_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
struct i2c_client *client = to_i2c_client(dev);
int rc;
u8 regs[7];
u8 ctrl1;
if ((tm->tm_year < 100) || (tm->tm_year > 199))
return -EINVAL;
/*
* to accurately set the time, reset the divider chain and keep it in
* reset state until all time/date registers are written
*/
rc = pcf85063_stop_clock(client, &ctrl1);
if (rc != 0)
return rc;
/* hours, minutes and seconds */
regs[0] = bin2bcd(tm->tm_sec) & 0x7F; /* clear OS flag */
regs[1] = bin2bcd(tm->tm_min);
regs[2] = bin2bcd(tm->tm_hour);
/* Day of month, 1 - 31 */
regs[3] = bin2bcd(tm->tm_mday);
/* Day, 0 - 6 */
regs[4] = tm->tm_wday & 0x07;
/* month, 1 - 12 */
regs[5] = bin2bcd(tm->tm_mon + 1);
/* year and century */
regs[6] = bin2bcd(tm->tm_year - 100);
/* write all registers at once */
rc = i2c_smbus_write_i2c_block_data(client, PCF85063_REG_SC,
sizeof(regs), regs);
if (rc < 0) {
dev_err(&client->dev, "date/time register write error\n");
return rc;
}
/*
* Write the control register as a separate action since the size of
* the register space is different between the PCF85063TP and
* PCF85063A devices. The rollover point can not be used.
*/
rc = pcf85063_start_clock(client, ctrl1);
if (rc != 0)
return rc;
return 0;
}
static const struct rtc_class_ops pcf85063_rtc_ops = {
.read_time = pcf85063_rtc_read_time,
.set_time = pcf85063_rtc_set_time
};
static int pcf85063_load_capacitance(struct i2c_client *client)
{
u32 load;
int rc;
u8 reg;
rc = i2c_smbus_read_byte_data(client, PCF85063_REG_CTRL1);
if (rc < 0)
return rc;
reg = rc;
load = 7000;
of_property_read_u32(client->dev.of_node, "quartz-load-femtofarads",
&load);
switch (load) {
default:
dev_warn(&client->dev, "Unknown quartz-load-femtofarads value: %d. Assuming 7000",
load);
/* fall through */
case 7000:
reg &= ~PCF85063_REG_CTRL1_CAP_SEL;
break;
case 12500:
reg |= PCF85063_REG_CTRL1_CAP_SEL;
break;
}
rc = i2c_smbus_write_byte_data(client, PCF85063_REG_CTRL1, reg);
return rc;
}
static int pcf85063_probe(struct i2c_client *client)
{
struct rtc_device *rtc;
int err;
dev_dbg(&client->dev, "%s\n", __func__);
err = i2c_smbus_read_byte_data(client, PCF85063_REG_CTRL1);
if (err < 0) {
dev_err(&client->dev, "RTC chip is not present\n");
return err;
}
err = pcf85063_load_capacitance(client);
if (err < 0)
dev_warn(&client->dev, "failed to set xtal load capacitance: %d",
err);
rtc = devm_rtc_allocate_device(&client->dev);
if (IS_ERR(rtc))
return PTR_ERR(rtc);
rtc->ops = &pcf85063_rtc_ops;
return rtc_register_device(rtc);
}
#ifdef CONFIG_OF
static const struct of_device_id pcf85063_of_match[] = {
{ .compatible = "nxp,pcf85063" },
{}
};
MODULE_DEVICE_TABLE(of, pcf85063_of_match);
#endif
static struct i2c_driver pcf85063_driver = {
.driver = {
.name = "rtc-pcf85063",
.of_match_table = of_match_ptr(pcf85063_of_match),
},
.probe_new = pcf85063_probe,
};
module_i2c_driver(pcf85063_driver);
MODULE_AUTHOR("Søren Andersen <san@rosetechnology.dk>");
MODULE_DESCRIPTION("PCF85063 RTC driver");
MODULE_LICENSE("GPL");
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