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linux/drivers/rtc/rtc-isl12057.c

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/*
* rtc-isl12057 - Driver for Intersil ISL12057 I2C Real Time Clock
*
* Copyright (C) 2013, Arnaud EBALARD <arno@natisbad.org>
*
* This work is largely based on Intersil ISL1208 driver developed by
* Hebert Valerio Riedel <hvr@gnu.org>.
*
* Detailed datasheet on which this development is based is available here:
*
* http://natisbad.org/NAS2/refs/ISL12057.pdf
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/rtc.h>
#include <linux/i2c.h>
#include <linux/bcd.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/regmap.h>
#define DRV_NAME "rtc-isl12057"
/* RTC section */
#define ISL12057_REG_RTC_SC 0x00 /* Seconds */
#define ISL12057_REG_RTC_MN 0x01 /* Minutes */
#define ISL12057_REG_RTC_HR 0x02 /* Hours */
#define ISL12057_REG_RTC_HR_PM BIT(5) /* AM/PM bit in 12h format */
#define ISL12057_REG_RTC_HR_MIL BIT(6) /* 24h/12h format */
#define ISL12057_REG_RTC_DW 0x03 /* Day of the Week */
#define ISL12057_REG_RTC_DT 0x04 /* Date */
#define ISL12057_REG_RTC_MO 0x05 /* Month */
#define ISL12057_REG_RTC_MO_CEN BIT(7) /* Century bit */
#define ISL12057_REG_RTC_YR 0x06 /* Year */
#define ISL12057_RTC_SEC_LEN 7
/* Alarm 1 section */
#define ISL12057_REG_A1_SC 0x07 /* Alarm 1 Seconds */
#define ISL12057_REG_A1_MN 0x08 /* Alarm 1 Minutes */
#define ISL12057_REG_A1_HR 0x09 /* Alarm 1 Hours */
#define ISL12057_REG_A1_HR_PM BIT(5) /* AM/PM bit in 12h format */
#define ISL12057_REG_A1_HR_MIL BIT(6) /* 24h/12h format */
#define ISL12057_REG_A1_DWDT 0x0A /* Alarm 1 Date / Day of the week */
#define ISL12057_REG_A1_DWDT_B BIT(6) /* DW / DT selection bit */
#define ISL12057_A1_SEC_LEN 4
/* Alarm 2 section */
#define ISL12057_REG_A2_MN 0x0B /* Alarm 2 Minutes */
#define ISL12057_REG_A2_HR 0x0C /* Alarm 2 Hours */
#define ISL12057_REG_A2_DWDT 0x0D /* Alarm 2 Date / Day of the week */
#define ISL12057_A2_SEC_LEN 3
/* Control/Status registers */
#define ISL12057_REG_INT 0x0E
#define ISL12057_REG_INT_A1IE BIT(0) /* Alarm 1 interrupt enable bit */
#define ISL12057_REG_INT_A2IE BIT(1) /* Alarm 2 interrupt enable bit */
#define ISL12057_REG_INT_INTCN BIT(2) /* Interrupt control enable bit */
#define ISL12057_REG_INT_RS1 BIT(3) /* Freq out control bit 1 */
#define ISL12057_REG_INT_RS2 BIT(4) /* Freq out control bit 2 */
#define ISL12057_REG_INT_EOSC BIT(7) /* Oscillator enable bit */
#define ISL12057_REG_SR 0x0F
#define ISL12057_REG_SR_A1F BIT(0) /* Alarm 1 interrupt bit */
#define ISL12057_REG_SR_A2F BIT(1) /* Alarm 2 interrupt bit */
#define ISL12057_REG_SR_OSF BIT(7) /* Oscillator failure bit */
/* Register memory map length */
#define ISL12057_MEM_MAP_LEN 0x10
struct isl12057_rtc_data {
struct regmap *regmap;
struct mutex lock;
};
static void isl12057_rtc_regs_to_tm(struct rtc_time *tm, u8 *regs)
{
tm->tm_sec = bcd2bin(regs[ISL12057_REG_RTC_SC]);
tm->tm_min = bcd2bin(regs[ISL12057_REG_RTC_MN]);
if (regs[ISL12057_REG_RTC_HR] & ISL12057_REG_RTC_HR_MIL) { /* AM/PM */
tm->tm_hour = bcd2bin(regs[ISL12057_REG_RTC_HR] & 0x1f);
if (regs[ISL12057_REG_RTC_HR] & ISL12057_REG_RTC_HR_PM)
tm->tm_hour += 12;
} else { /* 24 hour mode */
tm->tm_hour = bcd2bin(regs[ISL12057_REG_RTC_HR] & 0x3f);
}
tm->tm_mday = bcd2bin(regs[ISL12057_REG_RTC_DT]);
tm->tm_wday = bcd2bin(regs[ISL12057_REG_RTC_DW]) - 1; /* starts at 1 */
tm->tm_mon = bcd2bin(regs[ISL12057_REG_RTC_MO] & 0x1f) - 1; /* ditto */
tm->tm_year = bcd2bin(regs[ISL12057_REG_RTC_YR]) + 100;
/* Check if years register has overflown from 99 to 00 */
if (regs[ISL12057_REG_RTC_MO] & ISL12057_REG_RTC_MO_CEN)
tm->tm_year += 100;
}
static int isl12057_rtc_tm_to_regs(u8 *regs, struct rtc_time *tm)
{
u8 century_bit;
/*
* The clock has an 8 bit wide bcd-coded register for the year.
* It also has a century bit encoded in MO flag which provides
* information about overflow of year register from 99 to 00.
* tm_year is an offset from 1900 and we are interested in the
* 2000-2199 range, so any value less than 100 or larger than
* 299 is invalid.
*/
if (tm->tm_year < 100 || tm->tm_year > 299)
return -EINVAL;
century_bit = (tm->tm_year > 199) ? ISL12057_REG_RTC_MO_CEN : 0;
regs[ISL12057_REG_RTC_SC] = bin2bcd(tm->tm_sec);
regs[ISL12057_REG_RTC_MN] = bin2bcd(tm->tm_min);
regs[ISL12057_REG_RTC_HR] = bin2bcd(tm->tm_hour); /* 24-hour format */
regs[ISL12057_REG_RTC_DT] = bin2bcd(tm->tm_mday);
regs[ISL12057_REG_RTC_MO] = bin2bcd(tm->tm_mon + 1) | century_bit;
regs[ISL12057_REG_RTC_YR] = bin2bcd(tm->tm_year % 100);
regs[ISL12057_REG_RTC_DW] = bin2bcd(tm->tm_wday + 1);
return 0;
}
/*
* Try and match register bits w/ fixed null values to see whether we
* are dealing with an ISL12057. Note: this function is called early
* during init and hence does need mutex protection.
*/
static int isl12057_i2c_validate_chip(struct regmap *regmap)
{
u8 regs[ISL12057_MEM_MAP_LEN];
static const u8 mask[ISL12057_MEM_MAP_LEN] = { 0x80, 0x80, 0x80, 0xf8,
0xc0, 0x60, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x60, 0x7c };
int ret, i;
ret = regmap_bulk_read(regmap, 0, regs, ISL12057_MEM_MAP_LEN);
if (ret)
return ret;
for (i = 0; i < ISL12057_MEM_MAP_LEN; ++i) {
if (regs[i] & mask[i]) /* check if bits are cleared */
return -ENODEV;
}
return 0;
}
static int isl12057_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
struct isl12057_rtc_data *data = dev_get_drvdata(dev);
u8 regs[ISL12057_RTC_SEC_LEN];
unsigned int sr;
int ret;
mutex_lock(&data->lock);
ret = regmap_read(data->regmap, ISL12057_REG_SR, &sr);
if (ret) {
dev_err(dev, "%s: unable to read oscillator status flag (%d)\n",
__func__, ret);
goto out;
} else {
if (sr & ISL12057_REG_SR_OSF) {
ret = -ENODATA;
goto out;
}
}
ret = regmap_bulk_read(data->regmap, ISL12057_REG_RTC_SC, regs,
ISL12057_RTC_SEC_LEN);
if (ret)
dev_err(dev, "%s: unable to read RTC time section (%d)\n",
__func__, ret);
out:
mutex_unlock(&data->lock);
if (ret)
return ret;
isl12057_rtc_regs_to_tm(tm, regs);
return rtc_valid_tm(tm);
}
static int isl12057_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
struct isl12057_rtc_data *data = dev_get_drvdata(dev);
u8 regs[ISL12057_RTC_SEC_LEN];
int ret;
ret = isl12057_rtc_tm_to_regs(regs, tm);
if (ret)
return ret;
mutex_lock(&data->lock);
ret = regmap_bulk_write(data->regmap, ISL12057_REG_RTC_SC, regs,
ISL12057_RTC_SEC_LEN);
if (ret) {
dev_err(dev, "%s: unable to write RTC time section (%d)\n",
__func__, ret);
goto out;
}
/*
* Now that RTC time has been updated, let's clear oscillator
* failure flag, if needed.
*/
ret = regmap_update_bits(data->regmap, ISL12057_REG_SR,
ISL12057_REG_SR_OSF, 0);
if (ret < 0)
dev_err(dev, "%s: unable to clear osc. failure bit (%d)\n",
__func__, ret);
out:
mutex_unlock(&data->lock);
return ret;
}
/*
* Check current RTC status and enable/disable what needs to be. Return 0 if
* everything went ok and a negative value upon error. Note: this function
* is called early during init and hence does need mutex protection.
*/
static int isl12057_check_rtc_status(struct device *dev, struct regmap *regmap)
{
int ret;
/* Enable oscillator if not already running */
ret = regmap_update_bits(regmap, ISL12057_REG_INT,
ISL12057_REG_INT_EOSC, 0);
if (ret < 0) {
dev_err(dev, "%s: unable to enable oscillator (%d)\n",
__func__, ret);
return ret;
}
/* Clear alarm bit if needed */
ret = regmap_update_bits(regmap, ISL12057_REG_SR,
ISL12057_REG_SR_A1F, 0);
if (ret < 0) {
dev_err(dev, "%s: unable to clear alarm bit (%d)\n",
__func__, ret);
return ret;
}
return 0;
}
static const struct rtc_class_ops rtc_ops = {
.read_time = isl12057_rtc_read_time,
.set_time = isl12057_rtc_set_time,
};
static struct regmap_config isl12057_rtc_regmap_config = {
.reg_bits = 8,
.val_bits = 8,
};
static int isl12057_probe(struct i2c_client *client,
const struct i2c_device_id *id)
{
struct device *dev = &client->dev;
struct isl12057_rtc_data *data;
struct rtc_device *rtc;
struct regmap *regmap;
int ret;
if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C |
I2C_FUNC_SMBUS_BYTE_DATA |
I2C_FUNC_SMBUS_I2C_BLOCK))
return -ENODEV;
regmap = devm_regmap_init_i2c(client, &isl12057_rtc_regmap_config);
if (IS_ERR(regmap)) {
ret = PTR_ERR(regmap);
dev_err(dev, "%s: regmap allocation failed (%d)\n",
__func__, ret);
return ret;
}
ret = isl12057_i2c_validate_chip(regmap);
if (ret)
return ret;
ret = isl12057_check_rtc_status(dev, regmap);
if (ret)
return ret;
data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
if (!data)
return -ENOMEM;
mutex_init(&data->lock);
data->regmap = regmap;
dev_set_drvdata(dev, data);
rtc = devm_rtc_device_register(dev, DRV_NAME, &rtc_ops, THIS_MODULE);
return PTR_ERR_OR_ZERO(rtc);
}
#ifdef CONFIG_OF
static const struct of_device_id isl12057_dt_match[] = {
{ .compatible = "isl,isl12057" },
{ },
};
#endif
static const struct i2c_device_id isl12057_id[] = {
{ "isl12057", 0 },
{ }
};
MODULE_DEVICE_TABLE(i2c, isl12057_id);
static struct i2c_driver isl12057_driver = {
.driver = {
.name = DRV_NAME,
.owner = THIS_MODULE,
.of_match_table = of_match_ptr(isl12057_dt_match),
},
.probe = isl12057_probe,
.id_table = isl12057_id,
};
module_i2c_driver(isl12057_driver);
MODULE_AUTHOR("Arnaud EBALARD <arno@natisbad.org>");
MODULE_DESCRIPTION("Intersil ISL12057 RTC driver");
MODULE_LICENSE("GPL");
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