linux/drivers/rtc/rtc-pcf2127.c
Bruno Thomsen 0e735eaae1 rtc: pcf2127: add watchdog feature support
Add partial support for the watchdog functionality of
both PCF2127 and PCF2129 chips.

The programmable watchdog timer is currently using a fixed
clock source of 1Hz. This result in a selectable range of
1-255 seconds, which covers most embedded Linux use-cases.

Clock sources of 4096Hz, 64Hz and 1/60Hz is mostly useful
in MCU use-cases.

Countdown timer not available when using watchdog feature.

Signed-off-by: Bruno Thomsen <bruno.thomsen@gmail.com>
Acked-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20190822131936.18772-4-bruno.thomsen@gmail.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
2019-08-27 18:24:15 +02:00

621 lines
15 KiB
C

// SPDX-License-Identifier: GPL-2.0-only
/*
* An I2C and SPI driver for the NXP PCF2127/29 RTC
* Copyright 2013 Til-Technologies
*
* Author: Renaud Cerrato <r.cerrato@til-technologies.fr>
*
* Watchdog and tamper functions
* Author: Bruno Thomsen <bruno.thomsen@gmail.com>
*
* based on the other drivers in this same directory.
*
* Datasheet: http://cache.nxp.com/documents/data_sheet/PCF2127.pdf
*/
#include <linux/i2c.h>
#include <linux/spi/spi.h>
#include <linux/bcd.h>
#include <linux/rtc.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/regmap.h>
#include <linux/watchdog.h>
/* Control register 1 */
#define PCF2127_REG_CTRL1 0x00
/* Control register 2 */
#define PCF2127_REG_CTRL2 0x01
/* Control register 3 */
#define PCF2127_REG_CTRL3 0x02
#define PCF2127_BIT_CTRL3_BLF BIT(2)
/* Time and date registers */
#define PCF2127_REG_SC 0x03
#define PCF2127_BIT_SC_OSF BIT(7)
#define PCF2127_REG_MN 0x04
#define PCF2127_REG_HR 0x05
#define PCF2127_REG_DM 0x06
#define PCF2127_REG_DW 0x07
#define PCF2127_REG_MO 0x08
#define PCF2127_REG_YR 0x09
/* Watchdog registers */
#define PCF2127_REG_WD_CTL 0x10
#define PCF2127_BIT_WD_CTL_TF0 BIT(0)
#define PCF2127_BIT_WD_CTL_TF1 BIT(1)
#define PCF2127_BIT_WD_CTL_CD0 BIT(6)
#define PCF2127_BIT_WD_CTL_CD1 BIT(7)
#define PCF2127_REG_WD_VAL 0x11
/*
* RAM registers
* PCF2127 has 512 bytes general-purpose static RAM (SRAM) that is
* battery backed and can survive a power outage.
* PCF2129 doesn't have this feature.
*/
#define PCF2127_REG_RAM_ADDR_MSB 0x1A
#define PCF2127_REG_RAM_WRT_CMD 0x1C
#define PCF2127_REG_RAM_RD_CMD 0x1D
/* Watchdog timer value constants */
#define PCF2127_WD_VAL_STOP 0
#define PCF2127_WD_VAL_MIN 2
#define PCF2127_WD_VAL_MAX 255
#define PCF2127_WD_VAL_DEFAULT 60
struct pcf2127 {
struct rtc_device *rtc;
struct watchdog_device wdd;
struct regmap *regmap;
};
/*
* In the routines that deal directly with the pcf2127 hardware, we use
* rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch.
*/
static int pcf2127_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
struct pcf2127 *pcf2127 = dev_get_drvdata(dev);
unsigned char buf[10];
int ret;
/*
* Avoid reading CTRL2 register as it causes WD_VAL register
* value to reset to 0 which means watchdog is stopped.
*/
ret = regmap_bulk_read(pcf2127->regmap, PCF2127_REG_CTRL3,
(buf + PCF2127_REG_CTRL3),
ARRAY_SIZE(buf) - PCF2127_REG_CTRL3);
if (ret) {
dev_err(dev, "%s: read error\n", __func__);
return ret;
}
if (buf[PCF2127_REG_CTRL3] & PCF2127_BIT_CTRL3_BLF)
dev_info(dev,
"low voltage detected, check/replace RTC battery.\n");
/* Clock integrity is not guaranteed when OSF flag is set. */
if (buf[PCF2127_REG_SC] & PCF2127_BIT_SC_OSF) {
/*
* no need clear the flag here,
* it will be cleared once the new date is saved
*/
dev_warn(dev,
"oscillator stop detected, date/time is not reliable\n");
return -EINVAL;
}
dev_dbg(dev,
"%s: raw data is cr3=%02x, sec=%02x, min=%02x, hr=%02x, "
"mday=%02x, wday=%02x, mon=%02x, year=%02x\n",
__func__, buf[PCF2127_REG_CTRL3], buf[PCF2127_REG_SC],
buf[PCF2127_REG_MN], buf[PCF2127_REG_HR],
buf[PCF2127_REG_DM], buf[PCF2127_REG_DW],
buf[PCF2127_REG_MO], buf[PCF2127_REG_YR]);
tm->tm_sec = bcd2bin(buf[PCF2127_REG_SC] & 0x7F);
tm->tm_min = bcd2bin(buf[PCF2127_REG_MN] & 0x7F);
tm->tm_hour = bcd2bin(buf[PCF2127_REG_HR] & 0x3F); /* rtc hr 0-23 */
tm->tm_mday = bcd2bin(buf[PCF2127_REG_DM] & 0x3F);
tm->tm_wday = buf[PCF2127_REG_DW] & 0x07;
tm->tm_mon = bcd2bin(buf[PCF2127_REG_MO] & 0x1F) - 1; /* rtc mn 1-12 */
tm->tm_year = bcd2bin(buf[PCF2127_REG_YR]);
if (tm->tm_year < 70)
tm->tm_year += 100; /* assume we are in 1970...2069 */
dev_dbg(dev, "%s: tm is secs=%d, mins=%d, hours=%d, "
"mday=%d, mon=%d, year=%d, wday=%d\n",
__func__,
tm->tm_sec, tm->tm_min, tm->tm_hour,
tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
return 0;
}
static int pcf2127_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
struct pcf2127 *pcf2127 = dev_get_drvdata(dev);
unsigned char buf[7];
int i = 0, err;
dev_dbg(dev, "%s: secs=%d, mins=%d, hours=%d, "
"mday=%d, mon=%d, year=%d, wday=%d\n",
__func__,
tm->tm_sec, tm->tm_min, tm->tm_hour,
tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
/* hours, minutes and seconds */
buf[i++] = bin2bcd(tm->tm_sec); /* this will also clear OSF flag */
buf[i++] = bin2bcd(tm->tm_min);
buf[i++] = bin2bcd(tm->tm_hour);
buf[i++] = bin2bcd(tm->tm_mday);
buf[i++] = tm->tm_wday & 0x07;
/* month, 1 - 12 */
buf[i++] = bin2bcd(tm->tm_mon + 1);
/* year */
buf[i++] = bin2bcd(tm->tm_year % 100);
/* write register's data */
err = regmap_bulk_write(pcf2127->regmap, PCF2127_REG_SC, buf, i);
if (err) {
dev_err(dev,
"%s: err=%d", __func__, err);
return err;
}
return 0;
}
#ifdef CONFIG_RTC_INTF_DEV
static int pcf2127_rtc_ioctl(struct device *dev,
unsigned int cmd, unsigned long arg)
{
struct pcf2127 *pcf2127 = dev_get_drvdata(dev);
int touser;
int ret;
switch (cmd) {
case RTC_VL_READ:
ret = regmap_read(pcf2127->regmap, PCF2127_REG_CTRL3, &touser);
if (ret)
return ret;
touser = touser & PCF2127_BIT_CTRL3_BLF ? 1 : 0;
if (copy_to_user((void __user *)arg, &touser, sizeof(int)))
return -EFAULT;
return 0;
default:
return -ENOIOCTLCMD;
}
}
#else
#define pcf2127_rtc_ioctl NULL
#endif
static const struct rtc_class_ops pcf2127_rtc_ops = {
.ioctl = pcf2127_rtc_ioctl,
.read_time = pcf2127_rtc_read_time,
.set_time = pcf2127_rtc_set_time,
};
static int pcf2127_nvmem_read(void *priv, unsigned int offset,
void *val, size_t bytes)
{
struct pcf2127 *pcf2127 = priv;
int ret;
unsigned char offsetbuf[] = { offset >> 8, offset };
ret = regmap_bulk_write(pcf2127->regmap, PCF2127_REG_RAM_ADDR_MSB,
offsetbuf, 2);
if (ret)
return ret;
ret = regmap_bulk_read(pcf2127->regmap, PCF2127_REG_RAM_RD_CMD,
val, bytes);
return ret ?: bytes;
}
static int pcf2127_nvmem_write(void *priv, unsigned int offset,
void *val, size_t bytes)
{
struct pcf2127 *pcf2127 = priv;
int ret;
unsigned char offsetbuf[] = { offset >> 8, offset };
ret = regmap_bulk_write(pcf2127->regmap, PCF2127_REG_RAM_ADDR_MSB,
offsetbuf, 2);
if (ret)
return ret;
ret = regmap_bulk_write(pcf2127->regmap, PCF2127_REG_RAM_WRT_CMD,
val, bytes);
return ret ?: bytes;
}
/* watchdog driver */
static int pcf2127_wdt_ping(struct watchdog_device *wdd)
{
struct pcf2127 *pcf2127 = watchdog_get_drvdata(wdd);
return regmap_write(pcf2127->regmap, PCF2127_REG_WD_VAL, wdd->timeout);
}
/*
* Restart watchdog timer if feature is active.
*
* Note: Reading CTRL2 register causes watchdog to stop which is unfortunate,
* since register also contain control/status flags for other features.
* Always call this function after reading CTRL2 register.
*/
static int pcf2127_wdt_active_ping(struct watchdog_device *wdd)
{
int ret = 0;
if (watchdog_active(wdd)) {
ret = pcf2127_wdt_ping(wdd);
if (ret)
dev_err(wdd->parent,
"%s: watchdog restart failed, ret=%d\n",
__func__, ret);
}
return ret;
}
static int pcf2127_wdt_start(struct watchdog_device *wdd)
{
return pcf2127_wdt_ping(wdd);
}
static int pcf2127_wdt_stop(struct watchdog_device *wdd)
{
struct pcf2127 *pcf2127 = watchdog_get_drvdata(wdd);
return regmap_write(pcf2127->regmap, PCF2127_REG_WD_VAL,
PCF2127_WD_VAL_STOP);
}
static int pcf2127_wdt_set_timeout(struct watchdog_device *wdd,
unsigned int new_timeout)
{
dev_dbg(wdd->parent, "new watchdog timeout: %is (old: %is)\n",
new_timeout, wdd->timeout);
wdd->timeout = new_timeout;
return pcf2127_wdt_active_ping(wdd);
}
static const struct watchdog_info pcf2127_wdt_info = {
.identity = "NXP PCF2127/PCF2129 Watchdog",
.options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT,
};
static const struct watchdog_ops pcf2127_watchdog_ops = {
.owner = THIS_MODULE,
.start = pcf2127_wdt_start,
.stop = pcf2127_wdt_stop,
.ping = pcf2127_wdt_ping,
.set_timeout = pcf2127_wdt_set_timeout,
};
static int pcf2127_probe(struct device *dev, struct regmap *regmap,
const char *name, bool has_nvmem)
{
struct pcf2127 *pcf2127;
int ret = 0;
dev_dbg(dev, "%s\n", __func__);
pcf2127 = devm_kzalloc(dev, sizeof(*pcf2127), GFP_KERNEL);
if (!pcf2127)
return -ENOMEM;
pcf2127->regmap = regmap;
dev_set_drvdata(dev, pcf2127);
pcf2127->rtc = devm_rtc_allocate_device(dev);
if (IS_ERR(pcf2127->rtc))
return PTR_ERR(pcf2127->rtc);
pcf2127->rtc->ops = &pcf2127_rtc_ops;
pcf2127->wdd.parent = dev;
pcf2127->wdd.info = &pcf2127_wdt_info;
pcf2127->wdd.ops = &pcf2127_watchdog_ops;
pcf2127->wdd.min_timeout = PCF2127_WD_VAL_MIN;
pcf2127->wdd.max_timeout = PCF2127_WD_VAL_MAX;
pcf2127->wdd.timeout = PCF2127_WD_VAL_DEFAULT;
pcf2127->wdd.min_hw_heartbeat_ms = 500;
watchdog_set_drvdata(&pcf2127->wdd, pcf2127);
if (has_nvmem) {
struct nvmem_config nvmem_cfg = {
.priv = pcf2127,
.reg_read = pcf2127_nvmem_read,
.reg_write = pcf2127_nvmem_write,
.size = 512,
};
ret = rtc_nvmem_register(pcf2127->rtc, &nvmem_cfg);
}
/*
* Watchdog timer enabled and reset pin /RST activated when timed out.
* Select 1Hz clock source for watchdog timer.
* Timer is not started until WD_VAL is loaded with a valid value.
* Note: Countdown timer disabled and not available.
*/
ret = regmap_update_bits(pcf2127->regmap, PCF2127_REG_WD_CTL,
PCF2127_BIT_WD_CTL_CD1 |
PCF2127_BIT_WD_CTL_CD0 |
PCF2127_BIT_WD_CTL_TF1 |
PCF2127_BIT_WD_CTL_TF0,
PCF2127_BIT_WD_CTL_CD1 |
PCF2127_BIT_WD_CTL_CD0 |
PCF2127_BIT_WD_CTL_TF1);
if (ret) {
dev_err(dev, "%s: watchdog config (wd_ctl) failed\n", __func__);
return ret;
}
ret = devm_watchdog_register_device(dev, &pcf2127->wdd);
if (ret)
return ret;
return rtc_register_device(pcf2127->rtc);
}
#ifdef CONFIG_OF
static const struct of_device_id pcf2127_of_match[] = {
{ .compatible = "nxp,pcf2127" },
{ .compatible = "nxp,pcf2129" },
{}
};
MODULE_DEVICE_TABLE(of, pcf2127_of_match);
#endif
#if IS_ENABLED(CONFIG_I2C)
static int pcf2127_i2c_write(void *context, const void *data, size_t count)
{
struct device *dev = context;
struct i2c_client *client = to_i2c_client(dev);
int ret;
ret = i2c_master_send(client, data, count);
if (ret != count)
return ret < 0 ? ret : -EIO;
return 0;
}
static int pcf2127_i2c_gather_write(void *context,
const void *reg, size_t reg_size,
const void *val, size_t val_size)
{
struct device *dev = context;
struct i2c_client *client = to_i2c_client(dev);
int ret;
void *buf;
if (WARN_ON(reg_size != 1))
return -EINVAL;
buf = kmalloc(val_size + 1, GFP_KERNEL);
if (!buf)
return -ENOMEM;
memcpy(buf, reg, 1);
memcpy(buf + 1, val, val_size);
ret = i2c_master_send(client, buf, val_size + 1);
kfree(buf);
if (ret != val_size + 1)
return ret < 0 ? ret : -EIO;
return 0;
}
static int pcf2127_i2c_read(void *context, const void *reg, size_t reg_size,
void *val, size_t val_size)
{
struct device *dev = context;
struct i2c_client *client = to_i2c_client(dev);
int ret;
if (WARN_ON(reg_size != 1))
return -EINVAL;
ret = i2c_master_send(client, reg, 1);
if (ret != 1)
return ret < 0 ? ret : -EIO;
ret = i2c_master_recv(client, val, val_size);
if (ret != val_size)
return ret < 0 ? ret : -EIO;
return 0;
}
/*
* The reason we need this custom regmap_bus instead of using regmap_init_i2c()
* is that the STOP condition is required between set register address and
* read register data when reading from registers.
*/
static const struct regmap_bus pcf2127_i2c_regmap = {
.write = pcf2127_i2c_write,
.gather_write = pcf2127_i2c_gather_write,
.read = pcf2127_i2c_read,
};
static struct i2c_driver pcf2127_i2c_driver;
static int pcf2127_i2c_probe(struct i2c_client *client,
const struct i2c_device_id *id)
{
struct regmap *regmap;
static const struct regmap_config config = {
.reg_bits = 8,
.val_bits = 8,
};
if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
return -ENODEV;
regmap = devm_regmap_init(&client->dev, &pcf2127_i2c_regmap,
&client->dev, &config);
if (IS_ERR(regmap)) {
dev_err(&client->dev, "%s: regmap allocation failed: %ld\n",
__func__, PTR_ERR(regmap));
return PTR_ERR(regmap);
}
return pcf2127_probe(&client->dev, regmap,
pcf2127_i2c_driver.driver.name, id->driver_data);
}
static const struct i2c_device_id pcf2127_i2c_id[] = {
{ "pcf2127", 1 },
{ "pcf2129", 0 },
{ }
};
MODULE_DEVICE_TABLE(i2c, pcf2127_i2c_id);
static struct i2c_driver pcf2127_i2c_driver = {
.driver = {
.name = "rtc-pcf2127-i2c",
.of_match_table = of_match_ptr(pcf2127_of_match),
},
.probe = pcf2127_i2c_probe,
.id_table = pcf2127_i2c_id,
};
static int pcf2127_i2c_register_driver(void)
{
return i2c_add_driver(&pcf2127_i2c_driver);
}
static void pcf2127_i2c_unregister_driver(void)
{
i2c_del_driver(&pcf2127_i2c_driver);
}
#else
static int pcf2127_i2c_register_driver(void)
{
return 0;
}
static void pcf2127_i2c_unregister_driver(void)
{
}
#endif
#if IS_ENABLED(CONFIG_SPI_MASTER)
static struct spi_driver pcf2127_spi_driver;
static int pcf2127_spi_probe(struct spi_device *spi)
{
static const struct regmap_config config = {
.reg_bits = 8,
.val_bits = 8,
.read_flag_mask = 0xa0,
.write_flag_mask = 0x20,
};
struct regmap *regmap;
regmap = devm_regmap_init_spi(spi, &config);
if (IS_ERR(regmap)) {
dev_err(&spi->dev, "%s: regmap allocation failed: %ld\n",
__func__, PTR_ERR(regmap));
return PTR_ERR(regmap);
}
return pcf2127_probe(&spi->dev, regmap, pcf2127_spi_driver.driver.name,
spi_get_device_id(spi)->driver_data);
}
static const struct spi_device_id pcf2127_spi_id[] = {
{ "pcf2127", 1 },
{ "pcf2129", 0 },
{ }
};
MODULE_DEVICE_TABLE(spi, pcf2127_spi_id);
static struct spi_driver pcf2127_spi_driver = {
.driver = {
.name = "rtc-pcf2127-spi",
.of_match_table = of_match_ptr(pcf2127_of_match),
},
.probe = pcf2127_spi_probe,
.id_table = pcf2127_spi_id,
};
static int pcf2127_spi_register_driver(void)
{
return spi_register_driver(&pcf2127_spi_driver);
}
static void pcf2127_spi_unregister_driver(void)
{
spi_unregister_driver(&pcf2127_spi_driver);
}
#else
static int pcf2127_spi_register_driver(void)
{
return 0;
}
static void pcf2127_spi_unregister_driver(void)
{
}
#endif
static int __init pcf2127_init(void)
{
int ret;
ret = pcf2127_i2c_register_driver();
if (ret) {
pr_err("Failed to register pcf2127 i2c driver: %d\n", ret);
return ret;
}
ret = pcf2127_spi_register_driver();
if (ret) {
pr_err("Failed to register pcf2127 spi driver: %d\n", ret);
pcf2127_i2c_unregister_driver();
}
return ret;
}
module_init(pcf2127_init)
static void __exit pcf2127_exit(void)
{
pcf2127_spi_unregister_driver();
pcf2127_i2c_unregister_driver();
}
module_exit(pcf2127_exit)
MODULE_AUTHOR("Renaud Cerrato <r.cerrato@til-technologies.fr>");
MODULE_DESCRIPTION("NXP PCF2127/29 RTC driver");
MODULE_LICENSE("GPL v2");