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587 lines
14 KiB
587 lines
14 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* |
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* RTC client/driver for the Maxim/Dallas DS1374 Real-Time Clock over I2C |
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* |
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* Based on code by Randy Vinson <[email protected]>, |
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* which was based on the m41t00.c by Mark Greer <[email protected]>. |
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* |
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* Copyright (C) 2014 Rose Technology |
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* Copyright (C) 2006-2007 Freescale Semiconductor |
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* Copyright (c) 2005 MontaVista Software, Inc. |
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*/ |
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/* |
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* It would be more efficient to use i2c msgs/i2c_transfer directly but, as |
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* recommended in .../Documentation/i2c/writing-clients.rst section |
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* "Sending and receiving", using SMBus level communication is preferred. |
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*/ |
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
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#include <linux/kernel.h> |
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#include <linux/module.h> |
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#include <linux/interrupt.h> |
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#include <linux/i2c.h> |
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#include <linux/rtc.h> |
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#include <linux/bcd.h> |
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#include <linux/workqueue.h> |
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#include <linux/slab.h> |
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#include <linux/pm.h> |
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#ifdef CONFIG_RTC_DRV_DS1374_WDT |
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#include <linux/fs.h> |
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#include <linux/ioctl.h> |
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#include <linux/miscdevice.h> |
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#include <linux/reboot.h> |
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#include <linux/watchdog.h> |
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#endif |
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#define DS1374_REG_TOD0 0x00 /* Time of Day */ |
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#define DS1374_REG_TOD1 0x01 |
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#define DS1374_REG_TOD2 0x02 |
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#define DS1374_REG_TOD3 0x03 |
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#define DS1374_REG_WDALM0 0x04 /* Watchdog/Alarm */ |
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#define DS1374_REG_WDALM1 0x05 |
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#define DS1374_REG_WDALM2 0x06 |
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#define DS1374_REG_CR 0x07 /* Control */ |
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#define DS1374_REG_CR_AIE 0x01 /* Alarm Int. Enable */ |
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#define DS1374_REG_CR_WDSTR 0x08 /* 1=INT, 0=RST */ |
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#define DS1374_REG_CR_WDALM 0x20 /* 1=Watchdog, 0=Alarm */ |
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#define DS1374_REG_CR_WACE 0x40 /* WD/Alarm counter enable */ |
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#define DS1374_REG_SR 0x08 /* Status */ |
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#define DS1374_REG_SR_OSF 0x80 /* Oscillator Stop Flag */ |
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#define DS1374_REG_SR_AF 0x01 /* Alarm Flag */ |
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#define DS1374_REG_TCR 0x09 /* Trickle Charge */ |
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static const struct i2c_device_id ds1374_id[] = { |
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{ "ds1374", 0 }, |
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{ } |
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}; |
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MODULE_DEVICE_TABLE(i2c, ds1374_id); |
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#ifdef CONFIG_OF |
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static const struct of_device_id ds1374_of_match[] = { |
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{ .compatible = "dallas,ds1374" }, |
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{ } |
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}; |
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MODULE_DEVICE_TABLE(of, ds1374_of_match); |
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#endif |
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struct ds1374 { |
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struct i2c_client *client; |
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struct rtc_device *rtc; |
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struct work_struct work; |
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#ifdef CONFIG_RTC_DRV_DS1374_WDT |
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struct watchdog_device wdt; |
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#endif |
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/* The mutex protects alarm operations, and prevents a race |
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* between the enable_irq() in the workqueue and the free_irq() |
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* in the remove function. |
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*/ |
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struct mutex mutex; |
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int exiting; |
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}; |
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static struct i2c_driver ds1374_driver; |
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static int ds1374_read_rtc(struct i2c_client *client, u32 *time, |
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int reg, int nbytes) |
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{ |
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u8 buf[4]; |
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int ret; |
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int i; |
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if (WARN_ON(nbytes > 4)) |
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return -EINVAL; |
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ret = i2c_smbus_read_i2c_block_data(client, reg, nbytes, buf); |
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if (ret < 0) |
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return ret; |
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if (ret < nbytes) |
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return -EIO; |
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for (i = nbytes - 1, *time = 0; i >= 0; i--) |
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*time = (*time << 8) | buf[i]; |
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return 0; |
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} |
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static int ds1374_write_rtc(struct i2c_client *client, u32 time, |
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int reg, int nbytes) |
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{ |
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u8 buf[4]; |
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int i; |
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if (nbytes > 4) { |
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WARN_ON(1); |
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return -EINVAL; |
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} |
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for (i = 0; i < nbytes; i++) { |
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buf[i] = time & 0xff; |
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time >>= 8; |
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} |
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return i2c_smbus_write_i2c_block_data(client, reg, nbytes, buf); |
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} |
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static int ds1374_check_rtc_status(struct i2c_client *client) |
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{ |
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int ret = 0; |
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int control, stat; |
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stat = i2c_smbus_read_byte_data(client, DS1374_REG_SR); |
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if (stat < 0) |
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return stat; |
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if (stat & DS1374_REG_SR_OSF) |
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dev_warn(&client->dev, |
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"oscillator discontinuity flagged, time unreliable\n"); |
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stat &= ~(DS1374_REG_SR_OSF | DS1374_REG_SR_AF); |
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ret = i2c_smbus_write_byte_data(client, DS1374_REG_SR, stat); |
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if (ret < 0) |
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return ret; |
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/* If the alarm is pending, clear it before requesting |
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* the interrupt, so an interrupt event isn't reported |
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* before everything is initialized. |
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*/ |
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control = i2c_smbus_read_byte_data(client, DS1374_REG_CR); |
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if (control < 0) |
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return control; |
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control &= ~(DS1374_REG_CR_WACE | DS1374_REG_CR_AIE); |
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return i2c_smbus_write_byte_data(client, DS1374_REG_CR, control); |
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} |
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static int ds1374_read_time(struct device *dev, struct rtc_time *time) |
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{ |
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struct i2c_client *client = to_i2c_client(dev); |
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u32 itime; |
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int ret; |
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ret = ds1374_read_rtc(client, &itime, DS1374_REG_TOD0, 4); |
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if (!ret) |
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rtc_time64_to_tm(itime, time); |
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return ret; |
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} |
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static int ds1374_set_time(struct device *dev, struct rtc_time *time) |
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{ |
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struct i2c_client *client = to_i2c_client(dev); |
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unsigned long itime = rtc_tm_to_time64(time); |
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return ds1374_write_rtc(client, itime, DS1374_REG_TOD0, 4); |
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} |
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#ifndef CONFIG_RTC_DRV_DS1374_WDT |
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/* The ds1374 has a decrementer for an alarm, rather than a comparator. |
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* If the time of day is changed, then the alarm will need to be |
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* reset. |
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*/ |
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static int ds1374_read_alarm(struct device *dev, struct rtc_wkalrm *alarm) |
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{ |
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struct i2c_client *client = to_i2c_client(dev); |
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struct ds1374 *ds1374 = i2c_get_clientdata(client); |
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u32 now, cur_alarm; |
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int cr, sr; |
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int ret = 0; |
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if (client->irq <= 0) |
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return -EINVAL; |
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mutex_lock(&ds1374->mutex); |
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cr = ret = i2c_smbus_read_byte_data(client, DS1374_REG_CR); |
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if (ret < 0) |
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goto out; |
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sr = ret = i2c_smbus_read_byte_data(client, DS1374_REG_SR); |
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if (ret < 0) |
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goto out; |
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ret = ds1374_read_rtc(client, &now, DS1374_REG_TOD0, 4); |
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if (ret) |
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goto out; |
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ret = ds1374_read_rtc(client, &cur_alarm, DS1374_REG_WDALM0, 3); |
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if (ret) |
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goto out; |
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rtc_time64_to_tm(now + cur_alarm, &alarm->time); |
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alarm->enabled = !!(cr & DS1374_REG_CR_WACE); |
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alarm->pending = !!(sr & DS1374_REG_SR_AF); |
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out: |
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mutex_unlock(&ds1374->mutex); |
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return ret; |
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} |
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static int ds1374_set_alarm(struct device *dev, struct rtc_wkalrm *alarm) |
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{ |
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struct i2c_client *client = to_i2c_client(dev); |
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struct ds1374 *ds1374 = i2c_get_clientdata(client); |
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struct rtc_time now; |
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unsigned long new_alarm, itime; |
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int cr; |
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int ret = 0; |
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if (client->irq <= 0) |
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return -EINVAL; |
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ret = ds1374_read_time(dev, &now); |
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if (ret < 0) |
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return ret; |
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new_alarm = rtc_tm_to_time64(&alarm->time); |
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itime = rtc_tm_to_time64(&now); |
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/* This can happen due to races, in addition to dates that are |
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* truly in the past. To avoid requiring the caller to check for |
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* races, dates in the past are assumed to be in the recent past |
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* (i.e. not something that we'd rather the caller know about via |
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* an error), and the alarm is set to go off as soon as possible. |
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*/ |
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if (time_before_eq(new_alarm, itime)) |
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new_alarm = 1; |
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else |
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new_alarm -= itime; |
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mutex_lock(&ds1374->mutex); |
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ret = cr = i2c_smbus_read_byte_data(client, DS1374_REG_CR); |
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if (ret < 0) |
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goto out; |
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/* Disable any existing alarm before setting the new one |
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* (or lack thereof). */ |
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cr &= ~DS1374_REG_CR_WACE; |
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ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, cr); |
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if (ret < 0) |
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goto out; |
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ret = ds1374_write_rtc(client, new_alarm, DS1374_REG_WDALM0, 3); |
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if (ret) |
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goto out; |
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if (alarm->enabled) { |
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cr |= DS1374_REG_CR_WACE | DS1374_REG_CR_AIE; |
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cr &= ~DS1374_REG_CR_WDALM; |
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ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, cr); |
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} |
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out: |
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mutex_unlock(&ds1374->mutex); |
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return ret; |
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} |
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#endif |
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static irqreturn_t ds1374_irq(int irq, void *dev_id) |
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{ |
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struct i2c_client *client = dev_id; |
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struct ds1374 *ds1374 = i2c_get_clientdata(client); |
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disable_irq_nosync(irq); |
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schedule_work(&ds1374->work); |
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return IRQ_HANDLED; |
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} |
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static void ds1374_work(struct work_struct *work) |
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{ |
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struct ds1374 *ds1374 = container_of(work, struct ds1374, work); |
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struct i2c_client *client = ds1374->client; |
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int stat, control; |
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mutex_lock(&ds1374->mutex); |
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stat = i2c_smbus_read_byte_data(client, DS1374_REG_SR); |
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if (stat < 0) |
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goto unlock; |
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if (stat & DS1374_REG_SR_AF) { |
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stat &= ~DS1374_REG_SR_AF; |
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i2c_smbus_write_byte_data(client, DS1374_REG_SR, stat); |
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control = i2c_smbus_read_byte_data(client, DS1374_REG_CR); |
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if (control < 0) |
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goto out; |
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control &= ~(DS1374_REG_CR_WACE | DS1374_REG_CR_AIE); |
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i2c_smbus_write_byte_data(client, DS1374_REG_CR, control); |
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rtc_update_irq(ds1374->rtc, 1, RTC_AF | RTC_IRQF); |
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} |
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out: |
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if (!ds1374->exiting) |
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enable_irq(client->irq); |
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unlock: |
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mutex_unlock(&ds1374->mutex); |
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} |
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#ifndef CONFIG_RTC_DRV_DS1374_WDT |
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static int ds1374_alarm_irq_enable(struct device *dev, unsigned int enabled) |
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{ |
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struct i2c_client *client = to_i2c_client(dev); |
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struct ds1374 *ds1374 = i2c_get_clientdata(client); |
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int ret; |
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mutex_lock(&ds1374->mutex); |
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ret = i2c_smbus_read_byte_data(client, DS1374_REG_CR); |
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if (ret < 0) |
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goto out; |
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if (enabled) { |
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ret |= DS1374_REG_CR_WACE | DS1374_REG_CR_AIE; |
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ret &= ~DS1374_REG_CR_WDALM; |
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} else { |
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ret &= ~DS1374_REG_CR_WACE; |
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} |
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ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, ret); |
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out: |
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mutex_unlock(&ds1374->mutex); |
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return ret; |
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} |
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#endif |
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static const struct rtc_class_ops ds1374_rtc_ops = { |
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.read_time = ds1374_read_time, |
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.set_time = ds1374_set_time, |
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#ifndef CONFIG_RTC_DRV_DS1374_WDT |
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.read_alarm = ds1374_read_alarm, |
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.set_alarm = ds1374_set_alarm, |
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.alarm_irq_enable = ds1374_alarm_irq_enable, |
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#endif |
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}; |
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#ifdef CONFIG_RTC_DRV_DS1374_WDT |
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/* |
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***************************************************************************** |
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* |
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* Watchdog Driver |
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* |
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***************************************************************************** |
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*/ |
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/* Default margin */ |
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#define TIMER_MARGIN_DEFAULT 32 |
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#define TIMER_MARGIN_MIN 1 |
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#define TIMER_MARGIN_MAX 4095 /* 24-bit value */ |
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static int wdt_margin; |
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module_param(wdt_margin, int, 0); |
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MODULE_PARM_DESC(wdt_margin, "Watchdog timeout in seconds (default 32s)"); |
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static bool nowayout = WATCHDOG_NOWAYOUT; |
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module_param(nowayout, bool, 0); |
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MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default =" |
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__MODULE_STRING(WATCHDOG_NOWAYOUT)")"); |
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static const struct watchdog_info ds1374_wdt_info = { |
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.identity = "DS1374 Watchdog", |
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.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | |
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WDIOF_MAGICCLOSE, |
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}; |
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static int ds1374_wdt_settimeout(struct watchdog_device *wdt, unsigned int timeout) |
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{ |
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struct ds1374 *ds1374 = watchdog_get_drvdata(wdt); |
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struct i2c_client *client = ds1374->client; |
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int ret, cr; |
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wdt->timeout = timeout; |
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cr = i2c_smbus_read_byte_data(client, DS1374_REG_CR); |
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if (cr < 0) |
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return cr; |
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/* Disable any existing watchdog/alarm before setting the new one */ |
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cr &= ~DS1374_REG_CR_WACE; |
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ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, cr); |
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if (ret < 0) |
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return ret; |
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/* Set new watchdog time */ |
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timeout = timeout * 4096; |
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ret = ds1374_write_rtc(client, timeout, DS1374_REG_WDALM0, 3); |
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if (ret) |
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return ret; |
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/* Enable watchdog timer */ |
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cr |= DS1374_REG_CR_WACE | DS1374_REG_CR_WDALM; |
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cr &= ~DS1374_REG_CR_WDSTR;/* for RST PIN */ |
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cr &= ~DS1374_REG_CR_AIE; |
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ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, cr); |
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if (ret < 0) |
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return ret; |
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return 0; |
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} |
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/* |
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* Reload the watchdog timer. (ie, pat the watchdog) |
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*/ |
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static int ds1374_wdt_start(struct watchdog_device *wdt) |
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{ |
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struct ds1374 *ds1374 = watchdog_get_drvdata(wdt); |
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u32 val; |
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return ds1374_read_rtc(ds1374->client, &val, DS1374_REG_WDALM0, 3); |
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} |
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static int ds1374_wdt_stop(struct watchdog_device *wdt) |
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{ |
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struct ds1374 *ds1374 = watchdog_get_drvdata(wdt); |
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struct i2c_client *client = ds1374->client; |
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int cr; |
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cr = i2c_smbus_read_byte_data(client, DS1374_REG_CR); |
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if (cr < 0) |
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return cr; |
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/* Disable watchdog timer */ |
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cr &= ~DS1374_REG_CR_WACE; |
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return i2c_smbus_write_byte_data(client, DS1374_REG_CR, cr); |
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} |
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static const struct watchdog_ops ds1374_wdt_ops = { |
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.owner = THIS_MODULE, |
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.start = ds1374_wdt_start, |
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.stop = ds1374_wdt_stop, |
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.set_timeout = ds1374_wdt_settimeout, |
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}; |
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#endif /*CONFIG_RTC_DRV_DS1374_WDT*/ |
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/* |
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***************************************************************************** |
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* |
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* Driver Interface |
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* |
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***************************************************************************** |
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*/ |
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static int ds1374_probe(struct i2c_client *client, |
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const struct i2c_device_id *id) |
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{ |
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struct ds1374 *ds1374; |
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int ret; |
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ds1374 = devm_kzalloc(&client->dev, sizeof(struct ds1374), GFP_KERNEL); |
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if (!ds1374) |
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return -ENOMEM; |
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ds1374->rtc = devm_rtc_allocate_device(&client->dev); |
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if (IS_ERR(ds1374->rtc)) |
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return PTR_ERR(ds1374->rtc); |
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ds1374->client = client; |
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i2c_set_clientdata(client, ds1374); |
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INIT_WORK(&ds1374->work, ds1374_work); |
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mutex_init(&ds1374->mutex); |
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ret = ds1374_check_rtc_status(client); |
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if (ret) |
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return ret; |
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if (client->irq > 0) { |
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ret = devm_request_irq(&client->dev, client->irq, ds1374_irq, 0, |
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"ds1374", client); |
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if (ret) { |
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dev_err(&client->dev, "unable to request IRQ\n"); |
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return ret; |
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} |
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device_set_wakeup_capable(&client->dev, 1); |
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} |
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ds1374->rtc->ops = &ds1374_rtc_ops; |
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ds1374->rtc->range_max = U32_MAX; |
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ret = devm_rtc_register_device(ds1374->rtc); |
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if (ret) |
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return ret; |
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#ifdef CONFIG_RTC_DRV_DS1374_WDT |
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ds1374->wdt.info = &ds1374_wdt_info; |
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ds1374->wdt.ops = &ds1374_wdt_ops; |
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ds1374->wdt.timeout = TIMER_MARGIN_DEFAULT; |
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ds1374->wdt.min_timeout = TIMER_MARGIN_MIN; |
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ds1374->wdt.max_timeout = TIMER_MARGIN_MAX; |
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watchdog_init_timeout(&ds1374->wdt, wdt_margin, &client->dev); |
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watchdog_set_nowayout(&ds1374->wdt, nowayout); |
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watchdog_stop_on_reboot(&ds1374->wdt); |
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watchdog_stop_on_unregister(&ds1374->wdt); |
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watchdog_set_drvdata(&ds1374->wdt, ds1374); |
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ds1374_wdt_settimeout(&ds1374->wdt, ds1374->wdt.timeout); |
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ret = devm_watchdog_register_device(&client->dev, &ds1374->wdt); |
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if (ret) |
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return ret; |
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#endif |
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return 0; |
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} |
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static int ds1374_remove(struct i2c_client *client) |
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{ |
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struct ds1374 *ds1374 = i2c_get_clientdata(client); |
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if (client->irq > 0) { |
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mutex_lock(&ds1374->mutex); |
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ds1374->exiting = 1; |
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mutex_unlock(&ds1374->mutex); |
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devm_free_irq(&client->dev, client->irq, client); |
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cancel_work_sync(&ds1374->work); |
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} |
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return 0; |
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} |
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#ifdef CONFIG_PM_SLEEP |
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static int ds1374_suspend(struct device *dev) |
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{ |
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struct i2c_client *client = to_i2c_client(dev); |
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if (client->irq > 0 && device_may_wakeup(&client->dev)) |
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enable_irq_wake(client->irq); |
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return 0; |
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} |
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static int ds1374_resume(struct device *dev) |
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{ |
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struct i2c_client *client = to_i2c_client(dev); |
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if (client->irq > 0 && device_may_wakeup(&client->dev)) |
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disable_irq_wake(client->irq); |
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return 0; |
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} |
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#endif |
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static SIMPLE_DEV_PM_OPS(ds1374_pm, ds1374_suspend, ds1374_resume); |
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static struct i2c_driver ds1374_driver = { |
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.driver = { |
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.name = "rtc-ds1374", |
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.of_match_table = of_match_ptr(ds1374_of_match), |
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.pm = &ds1374_pm, |
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}, |
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.probe = ds1374_probe, |
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.remove = ds1374_remove, |
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.id_table = ds1374_id, |
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}; |
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module_i2c_driver(ds1374_driver); |
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MODULE_AUTHOR("Scott Wood <[email protected]>"); |
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MODULE_DESCRIPTION("Maxim/Dallas DS1374 RTC Driver"); |
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MODULE_LICENSE("GPL");
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