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linux/drivers/rtc/rtc-pcf85363.c
Alexandre Belloni 188306ac95 rtc: pcf85363: set time accurately 
As per 8.2.6 Setting and reading the time in RTC mode, first stop the clok,
then reset it before setting the date and time registers. Finally, start
the clock.

This uses register address wrap around from 0x2f to 0x00 for efficiency.

This allows to set the clock with a millisecond accuracy (drift is not
corrected in this example):

RTC        System
1325388767 1325388767.000029180
1325388768 1325388768.000018362
1325388769 1325388769.000006544
1325388770 1325388769.999992725
1325388771 1325388770.999974544

Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
2018-03-17 14:20:49 +01:00

398 lines
9.4 KiB
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/*
* drivers/rtc/rtc-pcf85363.c
*
* Driver for NXP PCF85363 real-time clock.
*
* Copyright (C) 2017 Eric Nelson
*
* 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.
*
* Based loosely on rtc-8583 by Russell King, Wolfram Sang and Juergen Beisert
*/
#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>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/regmap.h>
/*
* Date/Time registers
*/
#define DT_100THS 0x00
#define DT_SECS 0x01
#define DT_MINUTES 0x02
#define DT_HOURS 0x03
#define DT_DAYS 0x04
#define DT_WEEKDAYS 0x05
#define DT_MONTHS 0x06
#define DT_YEARS 0x07
/*
* Alarm registers
*/
#define DT_SECOND_ALM1 0x08
#define DT_MINUTE_ALM1 0x09
#define DT_HOUR_ALM1 0x0a
#define DT_DAY_ALM1 0x0b
#define DT_MONTH_ALM1 0x0c
#define DT_MINUTE_ALM2 0x0d
#define DT_HOUR_ALM2 0x0e
#define DT_WEEKDAY_ALM2 0x0f
#define DT_ALARM_EN 0x10
/*
* Time stamp registers
*/
#define DT_TIMESTAMP1 0x11
#define DT_TIMESTAMP2 0x17
#define DT_TIMESTAMP3 0x1d
#define DT_TS_MODE 0x23
/*
* control registers
*/
#define CTRL_OFFSET 0x24
#define CTRL_OSCILLATOR 0x25
#define CTRL_BATTERY 0x26
#define CTRL_PIN_IO 0x27
#define CTRL_FUNCTION 0x28
#define CTRL_INTA_EN 0x29
#define CTRL_INTB_EN 0x2a
#define CTRL_FLAGS 0x2b
#define CTRL_RAMBYTE 0x2c
#define CTRL_WDOG 0x2d
#define CTRL_STOP_EN 0x2e
#define CTRL_RESETS 0x2f
#define CTRL_RAM 0x40
#define ALRM_SEC_A1E BIT(0)
#define ALRM_MIN_A1E BIT(1)
#define ALRM_HR_A1E BIT(2)
#define ALRM_DAY_A1E BIT(3)
#define ALRM_MON_A1E BIT(4)
#define ALRM_MIN_A2E BIT(5)
#define ALRM_HR_A2E BIT(6)
#define ALRM_DAY_A2E BIT(7)
#define INT_WDIE BIT(0)
#define INT_BSIE BIT(1)
#define INT_TSRIE BIT(2)
#define INT_A2IE BIT(3)
#define INT_A1IE BIT(4)
#define INT_OIE BIT(5)
#define INT_PIE BIT(6)
#define INT_ILP BIT(7)
#define FLAGS_TSR1F BIT(0)
#define FLAGS_TSR2F BIT(1)
#define FLAGS_TSR3F BIT(2)
#define FLAGS_BSF BIT(3)
#define FLAGS_WDF BIT(4)
#define FLAGS_A1F BIT(5)
#define FLAGS_A2F BIT(6)
#define FLAGS_PIF BIT(7)
#define PIN_IO_INTAPM GENMASK(1, 0)
#define PIN_IO_INTA_CLK 0
#define PIN_IO_INTA_BAT 1
#define PIN_IO_INTA_OUT 2
#define PIN_IO_INTA_HIZ 3
#define STOP_EN_STOP BIT(0)
#define RESET_CPR 0xa4
#define NVRAM_SIZE 0x40
static struct i2c_driver pcf85363_driver;
struct pcf85363 {
struct device *dev;
struct rtc_device *rtc;
struct regmap *regmap;
};
static int pcf85363_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
struct pcf85363 *pcf85363 = dev_get_drvdata(dev);
unsigned char buf[DT_YEARS + 1];
int ret, len = sizeof(buf);
/* read the RTC date and time registers all at once */
ret = regmap_bulk_read(pcf85363->regmap, DT_100THS, buf, len);
if (ret) {
dev_err(dev, "%s: error %d\n", __func__, ret);
return ret;
}
tm->tm_year = bcd2bin(buf[DT_YEARS]);
/* adjust for 1900 base of rtc_time */
tm->tm_year += 100;
tm->tm_wday = buf[DT_WEEKDAYS] & 7;
buf[DT_SECS] &= 0x7F;
tm->tm_sec = bcd2bin(buf[DT_SECS]);
buf[DT_MINUTES] &= 0x7F;
tm->tm_min = bcd2bin(buf[DT_MINUTES]);
tm->tm_hour = bcd2bin(buf[DT_HOURS]);
tm->tm_mday = bcd2bin(buf[DT_DAYS]);
tm->tm_mon = bcd2bin(buf[DT_MONTHS]) - 1;
return 0;
}
static int pcf85363_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
struct pcf85363 *pcf85363 = dev_get_drvdata(dev);
unsigned char tmp[11];
unsigned char *buf = &tmp[2];
int ret;
tmp[0] = STOP_EN_STOP;
tmp[1] = RESET_CPR;
buf[DT_100THS] = 0;
buf[DT_SECS] = bin2bcd(tm->tm_sec);
buf[DT_MINUTES] = bin2bcd(tm->tm_min);
buf[DT_HOURS] = bin2bcd(tm->tm_hour);
buf[DT_DAYS] = bin2bcd(tm->tm_mday);
buf[DT_WEEKDAYS] = tm->tm_wday;
buf[DT_MONTHS] = bin2bcd(tm->tm_mon + 1);
buf[DT_YEARS] = bin2bcd(tm->tm_year % 100);
ret = regmap_bulk_write(pcf85363->regmap, CTRL_STOP_EN,
tmp, sizeof(tmp));
if (ret)
return ret;
return regmap_write(pcf85363->regmap, CTRL_STOP_EN, 0);
}
static int pcf85363_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
struct pcf85363 *pcf85363 = dev_get_drvdata(dev);
unsigned char buf[DT_MONTH_ALM1 - DT_SECOND_ALM1 + 1];
unsigned int val;
int ret;
ret = regmap_bulk_read(pcf85363->regmap, DT_SECOND_ALM1, buf,
sizeof(buf));
if (ret)
return ret;
alrm->time.tm_sec = bcd2bin(buf[0]);
alrm->time.tm_min = bcd2bin(buf[1]);
alrm->time.tm_hour = bcd2bin(buf[2]);
alrm->time.tm_mday = bcd2bin(buf[3]);
alrm->time.tm_mon = bcd2bin(buf[4]) - 1;
ret = regmap_read(pcf85363->regmap, CTRL_INTA_EN, &val);
if (ret)
return ret;
alrm->enabled = !!(val & INT_A1IE);
return 0;
}
static int _pcf85363_rtc_alarm_irq_enable(struct pcf85363 *pcf85363, unsigned
int enabled)
{
unsigned int alarm_flags = ALRM_SEC_A1E | ALRM_MIN_A1E | ALRM_HR_A1E |
ALRM_DAY_A1E | ALRM_MON_A1E;
int ret;
ret = regmap_update_bits(pcf85363->regmap, DT_ALARM_EN, alarm_flags,
enabled ? alarm_flags : 0);
if (ret)
return ret;
ret = regmap_update_bits(pcf85363->regmap, CTRL_INTA_EN,
INT_A1IE, enabled ? INT_A1IE : 0);
if (ret || enabled)
return ret;
/* clear current flags */
return regmap_update_bits(pcf85363->regmap, CTRL_FLAGS, FLAGS_A1F, 0);
}
static int pcf85363_rtc_alarm_irq_enable(struct device *dev,
unsigned int enabled)
{
struct pcf85363 *pcf85363 = dev_get_drvdata(dev);
return _pcf85363_rtc_alarm_irq_enable(pcf85363, enabled);
}
static int pcf85363_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
struct pcf85363 *pcf85363 = dev_get_drvdata(dev);
unsigned char buf[DT_MONTH_ALM1 - DT_SECOND_ALM1 + 1];
int ret;
buf[0] = bin2bcd(alrm->time.tm_sec);
buf[1] = bin2bcd(alrm->time.tm_min);
buf[2] = bin2bcd(alrm->time.tm_hour);
buf[3] = bin2bcd(alrm->time.tm_mday);
buf[4] = bin2bcd(alrm->time.tm_mon + 1);
/*
* Disable the alarm interrupt before changing the value to avoid
* spurious interrupts
*/
ret = _pcf85363_rtc_alarm_irq_enable(pcf85363, 0);
if (ret)
return ret;
ret = regmap_bulk_write(pcf85363->regmap, DT_SECOND_ALM1, buf,
sizeof(buf));
if (ret)
return ret;
return _pcf85363_rtc_alarm_irq_enable(pcf85363, alrm->enabled);
}
static irqreturn_t pcf85363_rtc_handle_irq(int irq, void *dev_id)
{
struct pcf85363 *pcf85363 = i2c_get_clientdata(dev_id);
unsigned int flags;
int err;
err = regmap_read(pcf85363->regmap, CTRL_FLAGS, &flags);
if (err)
return IRQ_NONE;
if (flags & FLAGS_A1F) {
rtc_update_irq(pcf85363->rtc, 1, RTC_IRQF | RTC_AF);
regmap_update_bits(pcf85363->regmap, CTRL_FLAGS, FLAGS_A1F, 0);
return IRQ_HANDLED;
}
return IRQ_NONE;
}
static const struct rtc_class_ops rtc_ops = {
.read_time = pcf85363_rtc_read_time,
.set_time = pcf85363_rtc_set_time,
};
static const struct rtc_class_ops rtc_ops_alarm = {
.read_time = pcf85363_rtc_read_time,
.set_time = pcf85363_rtc_set_time,
.read_alarm = pcf85363_rtc_read_alarm,
.set_alarm = pcf85363_rtc_set_alarm,
.alarm_irq_enable = pcf85363_rtc_alarm_irq_enable,
};
static int pcf85363_nvram_read(void *priv, unsigned int offset, void *val,
size_t bytes)
{
struct pcf85363 *pcf85363 = priv;
return regmap_bulk_read(pcf85363->regmap, CTRL_RAM + offset,
val, bytes);
}
static int pcf85363_nvram_write(void *priv, unsigned int offset, void *val,
size_t bytes)
{
struct pcf85363 *pcf85363 = priv;
return regmap_bulk_write(pcf85363->regmap, CTRL_RAM + offset,
val, bytes);
}
static const struct regmap_config regmap_config = {
.reg_bits = 8,
.val_bits = 8,
.max_register = 0x7f,
};
static int pcf85363_probe(struct i2c_client *client,
const struct i2c_device_id *id)
{
struct pcf85363 *pcf85363;
struct nvmem_config nvmem_cfg = {
.name = "pcf85363-",
.word_size = 1,
.stride = 1,
.size = NVRAM_SIZE,
.reg_read = pcf85363_nvram_read,
.reg_write = pcf85363_nvram_write,
};
int ret;
if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
return -ENODEV;
pcf85363 = devm_kzalloc(&client->dev, sizeof(struct pcf85363),
GFP_KERNEL);
if (!pcf85363)
return -ENOMEM;
pcf85363->regmap = devm_regmap_init_i2c(client, &regmap_config);
if (IS_ERR(pcf85363->regmap)) {
dev_err(&client->dev, "regmap allocation failed\n");
return PTR_ERR(pcf85363->regmap);
}
pcf85363->dev = &client->dev;
i2c_set_clientdata(client, pcf85363);
pcf85363->rtc = devm_rtc_allocate_device(pcf85363->dev);
if (IS_ERR(pcf85363->rtc))
return PTR_ERR(pcf85363->rtc);
pcf85363->rtc->ops = &rtc_ops;
if (client->irq > 0) {
regmap_write(pcf85363->regmap, CTRL_FLAGS, 0);
regmap_update_bits(pcf85363->regmap, CTRL_PIN_IO,
PIN_IO_INTA_OUT, PIN_IO_INTAPM);
ret = devm_request_threaded_irq(pcf85363->dev, client->irq,
NULL, pcf85363_rtc_handle_irq,
IRQF_TRIGGER_LOW | IRQF_ONESHOT,
"pcf85363", client);
if (ret)
dev_warn(&client->dev, "unable to request IRQ, alarms disabled\n");
else
pcf85363->rtc->ops = &rtc_ops_alarm;
}
ret = rtc_register_device(pcf85363->rtc);
nvmem_cfg.priv = pcf85363;
rtc_nvmem_register(pcf85363->rtc, &nvmem_cfg);
return ret;
}
static const struct of_device_id dev_ids[] = {
{ .compatible = "nxp,pcf85363" },
{}
};
MODULE_DEVICE_TABLE(of, dev_ids);
static struct i2c_driver pcf85363_driver = {
.driver = {
.name = "pcf85363",
.of_match_table = of_match_ptr(dev_ids),
},
.probe = pcf85363_probe,
};
module_i2c_driver(pcf85363_driver);
MODULE_AUTHOR("Eric Nelson");
MODULE_DESCRIPTION("pcf85363 I2C RTC driver");
MODULE_LICENSE("GPL");
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