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linux/drivers/rtc/rtc-at91rm9200.c
Bartosz Golaszewski fdcfd85433 rtc: rework rtc_register_device() resource management 
rtc_register_device() is a managed interface but it doesn't use devres
by itself - instead it marks an rtc_device as "registered" and the devres
callback for devm_rtc_allocate_device() takes care of resource release.

This doesn't correspond with the design behind devres where managed
structures should not be aware of being managed. The correct solution
here is to register a separate devres callback for unregistering the
device.

While at it: rename rtc_register_device() to devm_rtc_register_device()
and add it to the list of managed interfaces in devres.rst. This way we
can avoid any potential confusion of driver developers who may expect
there to exist a corresponding unregister function.

Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/20201109163409.24301-8-brgl@bgdev.pl
2020-11-19 12:50:12 +01:00

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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Real Time Clock interface for Linux on Atmel AT91RM9200
*
* Copyright (C) 2002 Rick Bronson
*
* Converted to RTC class model by Andrew Victor
*
* Ported to Linux 2.6 by Steven Scholz
* Based on s3c2410-rtc.c Simtec Electronics
*
* Based on sa1100-rtc.c by Nils Faerber
* Based on rtc.c by Paul Gortmaker
*/
#include <linux/bcd.h>
#include <linux/bitfield.h>
#include <linux/clk.h>
#include <linux/completion.h>
#include <linux/interrupt.h>
#include <linux/ioctl.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of_device.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/rtc.h>
#include <linux/spinlock.h>
#include <linux/suspend.h>
#include <linux/time.h>
#include <linux/uaccess.h>
#define AT91_RTC_CR 0x00 /* Control Register */
#define AT91_RTC_UPDTIM BIT(0) /* Update Request Time Register */
#define AT91_RTC_UPDCAL BIT(1) /* Update Request Calendar Register */
#define AT91_RTC_MR 0x04 /* Mode Register */
#define AT91_RTC_HRMOD BIT(0) /* 12/24 hour mode */
#define AT91_RTC_NEGPPM BIT(4) /* Negative PPM correction */
#define AT91_RTC_CORRECTION GENMASK(14, 8) /* Slow clock correction */
#define AT91_RTC_HIGHPPM BIT(15) /* High PPM correction */
#define AT91_RTC_TIMR 0x08 /* Time Register */
#define AT91_RTC_SEC GENMASK(6, 0) /* Current Second */
#define AT91_RTC_MIN GENMASK(14, 8) /* Current Minute */
#define AT91_RTC_HOUR GENMASK(21, 16) /* Current Hour */
#define AT91_RTC_AMPM BIT(22) /* Ante Meridiem Post Meridiem Indicator */
#define AT91_RTC_CALR 0x0c /* Calendar Register */
#define AT91_RTC_CENT GENMASK(6, 0) /* Current Century */
#define AT91_RTC_YEAR GENMASK(15, 8) /* Current Year */
#define AT91_RTC_MONTH GENMASK(20, 16) /* Current Month */
#define AT91_RTC_DAY GENMASK(23, 21) /* Current Day */
#define AT91_RTC_DATE GENMASK(29, 24) /* Current Date */
#define AT91_RTC_TIMALR 0x10 /* Time Alarm Register */
#define AT91_RTC_SECEN BIT(7) /* Second Alarm Enable */
#define AT91_RTC_MINEN BIT(15) /* Minute Alarm Enable */
#define AT91_RTC_HOUREN BIT(23) /* Hour Alarm Enable */
#define AT91_RTC_CALALR 0x14 /* Calendar Alarm Register */
#define AT91_RTC_MTHEN BIT(23) /* Month Alarm Enable */
#define AT91_RTC_DATEEN BIT(31) /* Date Alarm Enable */
#define AT91_RTC_SR 0x18 /* Status Register */
#define AT91_RTC_ACKUPD BIT(0) /* Acknowledge for Update */
#define AT91_RTC_ALARM BIT(1) /* Alarm Flag */
#define AT91_RTC_SECEV BIT(2) /* Second Event */
#define AT91_RTC_TIMEV BIT(3) /* Time Event */
#define AT91_RTC_CALEV BIT(4) /* Calendar Event */
#define AT91_RTC_SCCR 0x1c /* Status Clear Command Register */
#define AT91_RTC_IER 0x20 /* Interrupt Enable Register */
#define AT91_RTC_IDR 0x24 /* Interrupt Disable Register */
#define AT91_RTC_IMR 0x28 /* Interrupt Mask Register */
#define AT91_RTC_VER 0x2c /* Valid Entry Register */
#define AT91_RTC_NVTIM BIT(0) /* Non valid Time */
#define AT91_RTC_NVCAL BIT(1) /* Non valid Calendar */
#define AT91_RTC_NVTIMALR BIT(2) /* Non valid Time Alarm */
#define AT91_RTC_NVCALALR BIT(3) /* Non valid Calendar Alarm */
#define AT91_RTC_CORR_DIVIDEND 3906000
#define AT91_RTC_CORR_LOW_RATIO 20
#define at91_rtc_read(field) \
readl_relaxed(at91_rtc_regs + field)
#define at91_rtc_write(field, val) \
writel_relaxed((val), at91_rtc_regs + field)
struct at91_rtc_config {
bool use_shadow_imr;
bool has_correction;
};
static const struct at91_rtc_config *at91_rtc_config;
static DECLARE_COMPLETION(at91_rtc_updated);
static DECLARE_COMPLETION(at91_rtc_upd_rdy);
static void __iomem *at91_rtc_regs;
static int irq;
static DEFINE_SPINLOCK(at91_rtc_lock);
static u32 at91_rtc_shadow_imr;
static bool suspended;
static DEFINE_SPINLOCK(suspended_lock);
static unsigned long cached_events;
static u32 at91_rtc_imr;
static struct clk *sclk;
static void at91_rtc_write_ier(u32 mask)
{
unsigned long flags;
spin_lock_irqsave(&at91_rtc_lock, flags);
at91_rtc_shadow_imr |= mask;
at91_rtc_write(AT91_RTC_IER, mask);
spin_unlock_irqrestore(&at91_rtc_lock, flags);
}
static void at91_rtc_write_idr(u32 mask)
{
unsigned long flags;
spin_lock_irqsave(&at91_rtc_lock, flags);
at91_rtc_write(AT91_RTC_IDR, mask);
/*
* Register read back (of any RTC-register) needed to make sure
* IDR-register write has reached the peripheral before updating
* shadow mask.
*
* Note that there is still a possibility that the mask is updated
* before interrupts have actually been disabled in hardware. The only
* way to be certain would be to poll the IMR-register, which is is
* the very register we are trying to emulate. The register read back
* is a reasonable heuristic.
*/
at91_rtc_read(AT91_RTC_SR);
at91_rtc_shadow_imr &= ~mask;
spin_unlock_irqrestore(&at91_rtc_lock, flags);
}
static u32 at91_rtc_read_imr(void)
{
unsigned long flags;
u32 mask;
if (at91_rtc_config->use_shadow_imr) {
spin_lock_irqsave(&at91_rtc_lock, flags);
mask = at91_rtc_shadow_imr;
spin_unlock_irqrestore(&at91_rtc_lock, flags);
} else {
mask = at91_rtc_read(AT91_RTC_IMR);
}
return mask;
}
/*
* Decode time/date into rtc_time structure
*/
static void at91_rtc_decodetime(unsigned int timereg, unsigned int calreg,
struct rtc_time *tm)
{
unsigned int time, date;
/* must read twice in case it changes */
do {
time = at91_rtc_read(timereg);
date = at91_rtc_read(calreg);
} while ((time != at91_rtc_read(timereg)) ||
(date != at91_rtc_read(calreg)));
tm->tm_sec = bcd2bin(FIELD_GET(AT91_RTC_SEC, time));
tm->tm_min = bcd2bin(FIELD_GET(AT91_RTC_MIN, time));
tm->tm_hour = bcd2bin(FIELD_GET(AT91_RTC_HOUR, time));
/*
* The Calendar Alarm register does not have a field for
* the year - so these will return an invalid value.
*/
tm->tm_year = bcd2bin(date & AT91_RTC_CENT) * 100; /* century */
tm->tm_year += bcd2bin(FIELD_GET(AT91_RTC_YEAR, date)); /* year */
tm->tm_wday = bcd2bin(FIELD_GET(AT91_RTC_DAY, date)) - 1; /* day of the week [0-6], Sunday=0 */
tm->tm_mon = bcd2bin(FIELD_GET(AT91_RTC_MONTH, date)) - 1;
tm->tm_mday = bcd2bin(FIELD_GET(AT91_RTC_DATE, date));
}
/*
* Read current time and date in RTC
*/
static int at91_rtc_readtime(struct device *dev, struct rtc_time *tm)
{
at91_rtc_decodetime(AT91_RTC_TIMR, AT91_RTC_CALR, tm);
tm->tm_yday = rtc_year_days(tm->tm_mday, tm->tm_mon, tm->tm_year);
tm->tm_year = tm->tm_year - 1900;
dev_dbg(dev, "%s(): %ptR\n", __func__, tm);
return 0;
}
/*
* Set current time and date in RTC
*/
static int at91_rtc_settime(struct device *dev, struct rtc_time *tm)
{
unsigned long cr;
dev_dbg(dev, "%s(): %ptR\n", __func__, tm);
wait_for_completion(&at91_rtc_upd_rdy);
/* Stop Time/Calendar from counting */
cr = at91_rtc_read(AT91_RTC_CR);
at91_rtc_write(AT91_RTC_CR, cr | AT91_RTC_UPDCAL | AT91_RTC_UPDTIM);
at91_rtc_write_ier(AT91_RTC_ACKUPD);
wait_for_completion(&at91_rtc_updated); /* wait for ACKUPD interrupt */
at91_rtc_write_idr(AT91_RTC_ACKUPD);
at91_rtc_write(AT91_RTC_TIMR,
FIELD_PREP(AT91_RTC_SEC, bin2bcd(tm->tm_sec))
| FIELD_PREP(AT91_RTC_MIN, bin2bcd(tm->tm_min))
| FIELD_PREP(AT91_RTC_HOUR, bin2bcd(tm->tm_hour)));
at91_rtc_write(AT91_RTC_CALR,
FIELD_PREP(AT91_RTC_CENT,
bin2bcd((tm->tm_year + 1900) / 100))
| FIELD_PREP(AT91_RTC_YEAR, bin2bcd(tm->tm_year % 100))
| FIELD_PREP(AT91_RTC_MONTH, bin2bcd(tm->tm_mon + 1))
| FIELD_PREP(AT91_RTC_DAY, bin2bcd(tm->tm_wday + 1))
| FIELD_PREP(AT91_RTC_DATE, bin2bcd(tm->tm_mday)));
/* Restart Time/Calendar */
cr = at91_rtc_read(AT91_RTC_CR);
at91_rtc_write(AT91_RTC_SCCR, AT91_RTC_SECEV);
at91_rtc_write(AT91_RTC_CR, cr & ~(AT91_RTC_UPDCAL | AT91_RTC_UPDTIM));
at91_rtc_write_ier(AT91_RTC_SECEV);
return 0;
}
/*
* Read alarm time and date in RTC
*/
static int at91_rtc_readalarm(struct device *dev, struct rtc_wkalrm *alrm)
{
struct rtc_time *tm = &alrm->time;
at91_rtc_decodetime(AT91_RTC_TIMALR, AT91_RTC_CALALR, tm);
tm->tm_year = -1;
alrm->enabled = (at91_rtc_read_imr() & AT91_RTC_ALARM)
? 1 : 0;
dev_dbg(dev, "%s(): %ptR %sabled\n", __func__, tm,
alrm->enabled ? "en" : "dis");
return 0;
}
/*
* Set alarm time and date in RTC
*/
static int at91_rtc_setalarm(struct device *dev, struct rtc_wkalrm *alrm)
{
struct rtc_time tm = alrm->time;
at91_rtc_write_idr(AT91_RTC_ALARM);
at91_rtc_write(AT91_RTC_TIMALR,
FIELD_PREP(AT91_RTC_SEC, bin2bcd(alrm->time.tm_sec))
| FIELD_PREP(AT91_RTC_MIN, bin2bcd(alrm->time.tm_min))
| FIELD_PREP(AT91_RTC_HOUR, bin2bcd(alrm->time.tm_hour))
| AT91_RTC_HOUREN | AT91_RTC_MINEN | AT91_RTC_SECEN);
at91_rtc_write(AT91_RTC_CALALR,
FIELD_PREP(AT91_RTC_MONTH, bin2bcd(alrm->time.tm_mon + 1))
| FIELD_PREP(AT91_RTC_DATE, bin2bcd(alrm->time.tm_mday))
| AT91_RTC_DATEEN | AT91_RTC_MTHEN);
if (alrm->enabled) {
at91_rtc_write(AT91_RTC_SCCR, AT91_RTC_ALARM);
at91_rtc_write_ier(AT91_RTC_ALARM);
}
dev_dbg(dev, "%s(): %ptR\n", __func__, &tm);
return 0;
}
static int at91_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
{
dev_dbg(dev, "%s(): cmd=%08x\n", __func__, enabled);
if (enabled) {
at91_rtc_write(AT91_RTC_SCCR, AT91_RTC_ALARM);
at91_rtc_write_ier(AT91_RTC_ALARM);
} else
at91_rtc_write_idr(AT91_RTC_ALARM);
return 0;
}
static int at91_rtc_readoffset(struct device *dev, long *offset)
{
u32 mr = at91_rtc_read(AT91_RTC_MR);
long val = FIELD_GET(AT91_RTC_CORRECTION, mr);
if (!val) {
*offset = 0;
return 0;
}
val++;
if (!(mr & AT91_RTC_NEGPPM))
val = -val;
if (!(mr & AT91_RTC_HIGHPPM))
val *= AT91_RTC_CORR_LOW_RATIO;
*offset = DIV_ROUND_CLOSEST(AT91_RTC_CORR_DIVIDEND, val);
return 0;
}
static int at91_rtc_setoffset(struct device *dev, long offset)
{
long corr;
u32 mr;
if (offset > AT91_RTC_CORR_DIVIDEND / 2)
return -ERANGE;
if (offset < -AT91_RTC_CORR_DIVIDEND / 2)
return -ERANGE;
mr = at91_rtc_read(AT91_RTC_MR);
mr &= ~(AT91_RTC_NEGPPM | AT91_RTC_CORRECTION | AT91_RTC_HIGHPPM);
if (offset > 0)
mr |= AT91_RTC_NEGPPM;
else
offset = -offset;
/* offset less than 764 ppb, disable correction*/
if (offset < 764) {
at91_rtc_write(AT91_RTC_MR, mr & ~AT91_RTC_NEGPPM);
return 0;
}
/*
* 29208 ppb is the perfect cutoff between low range and high range
* low range values are never better than high range value after that.
*/
if (offset < 29208) {
corr = DIV_ROUND_CLOSEST(AT91_RTC_CORR_DIVIDEND, offset * AT91_RTC_CORR_LOW_RATIO);
} else {
corr = DIV_ROUND_CLOSEST(AT91_RTC_CORR_DIVIDEND, offset);
mr |= AT91_RTC_HIGHPPM;
}
if (corr > 128)
corr = 128;
mr |= FIELD_PREP(AT91_RTC_CORRECTION, corr - 1);
at91_rtc_write(AT91_RTC_MR, mr);
return 0;
}
/*
* IRQ handler for the RTC
*/
static irqreturn_t at91_rtc_interrupt(int irq, void *dev_id)
{
struct platform_device *pdev = dev_id;
struct rtc_device *rtc = platform_get_drvdata(pdev);
unsigned int rtsr;
unsigned long events = 0;
int ret = IRQ_NONE;
spin_lock(&suspended_lock);
rtsr = at91_rtc_read(AT91_RTC_SR) & at91_rtc_read_imr();
if (rtsr) { /* this interrupt is shared! Is it ours? */
if (rtsr & AT91_RTC_ALARM)
events |= (RTC_AF | RTC_IRQF);
if (rtsr & AT91_RTC_SECEV) {
complete(&at91_rtc_upd_rdy);
at91_rtc_write_idr(AT91_RTC_SECEV);
}
if (rtsr & AT91_RTC_ACKUPD)
complete(&at91_rtc_updated);
at91_rtc_write(AT91_RTC_SCCR, rtsr); /* clear status reg */
if (!suspended) {
rtc_update_irq(rtc, 1, events);
dev_dbg(&pdev->dev, "%s(): num=%ld, events=0x%02lx\n",
__func__, events >> 8, events & 0x000000FF);
} else {
cached_events |= events;
at91_rtc_write_idr(at91_rtc_imr);
pm_system_wakeup();
}
ret = IRQ_HANDLED;
}
spin_unlock(&suspended_lock);
return ret;
}
static const struct at91_rtc_config at91rm9200_config = {
};
static const struct at91_rtc_config at91sam9x5_config = {
.use_shadow_imr = true,
};
static const struct at91_rtc_config sama5d4_config = {
.has_correction = true,
};
static const struct of_device_id at91_rtc_dt_ids[] = {
{
.compatible = "atmel,at91rm9200-rtc",
.data = &at91rm9200_config,
}, {
.compatible = "atmel,at91sam9x5-rtc",
.data = &at91sam9x5_config,
}, {
.compatible = "atmel,sama5d4-rtc",
.data = &sama5d4_config,
}, {
.compatible = "atmel,sama5d2-rtc",
.data = &sama5d4_config,
}, {
.compatible = "microchip,sam9x60-rtc",
.data = &sama5d4_config,
}, {
/* sentinel */
}
};
MODULE_DEVICE_TABLE(of, at91_rtc_dt_ids);
static const struct rtc_class_ops at91_rtc_ops = {
.read_time = at91_rtc_readtime,
.set_time = at91_rtc_settime,
.read_alarm = at91_rtc_readalarm,
.set_alarm = at91_rtc_setalarm,
.alarm_irq_enable = at91_rtc_alarm_irq_enable,
};
static const struct rtc_class_ops sama5d4_rtc_ops = {
.read_time = at91_rtc_readtime,
.set_time = at91_rtc_settime,
.read_alarm = at91_rtc_readalarm,
.set_alarm = at91_rtc_setalarm,
.alarm_irq_enable = at91_rtc_alarm_irq_enable,
.set_offset = at91_rtc_setoffset,
.read_offset = at91_rtc_readoffset,
};
/*
* Initialize and install RTC driver
*/
static int __init at91_rtc_probe(struct platform_device *pdev)
{
struct rtc_device *rtc;
struct resource *regs;
int ret = 0;
at91_rtc_config = of_device_get_match_data(&pdev->dev);
if (!at91_rtc_config)
return -ENODEV;
regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
if (!regs) {
dev_err(&pdev->dev, "no mmio resource defined\n");
return -ENXIO;
}
irq = platform_get_irq(pdev, 0);
if (irq < 0)
return -ENXIO;
at91_rtc_regs = devm_ioremap(&pdev->dev, regs->start,
resource_size(regs));
if (!at91_rtc_regs) {
dev_err(&pdev->dev, "failed to map registers, aborting.\n");
return -ENOMEM;
}
rtc = devm_rtc_allocate_device(&pdev->dev);
if (IS_ERR(rtc))
return PTR_ERR(rtc);
platform_set_drvdata(pdev, rtc);
sclk = devm_clk_get(&pdev->dev, NULL);
if (IS_ERR(sclk))
return PTR_ERR(sclk);
ret = clk_prepare_enable(sclk);
if (ret) {
dev_err(&pdev->dev, "Could not enable slow clock\n");
return ret;
}
at91_rtc_write(AT91_RTC_CR, 0);
at91_rtc_write(AT91_RTC_MR, at91_rtc_read(AT91_RTC_MR) & ~AT91_RTC_HRMOD);
/* Disable all interrupts */
at91_rtc_write_idr(AT91_RTC_ACKUPD | AT91_RTC_ALARM |
AT91_RTC_SECEV | AT91_RTC_TIMEV |
AT91_RTC_CALEV);
ret = devm_request_irq(&pdev->dev, irq, at91_rtc_interrupt,
IRQF_SHARED | IRQF_COND_SUSPEND,
"at91_rtc", pdev);
if (ret) {
dev_err(&pdev->dev, "IRQ %d already in use.\n", irq);
goto err_clk;
}
/* cpu init code should really have flagged this device as
* being wake-capable; if it didn't, do that here.
*/
if (!device_can_wakeup(&pdev->dev))
device_init_wakeup(&pdev->dev, 1);
if (at91_rtc_config->has_correction)
rtc->ops = &sama5d4_rtc_ops;
else
rtc->ops = &at91_rtc_ops;
rtc->range_min = RTC_TIMESTAMP_BEGIN_1900;
rtc->range_max = RTC_TIMESTAMP_END_2099;
ret = devm_rtc_register_device(rtc);
if (ret)
goto err_clk;
/* enable SECEV interrupt in order to initialize at91_rtc_upd_rdy
* completion.
*/
at91_rtc_write_ier(AT91_RTC_SECEV);
dev_info(&pdev->dev, "AT91 Real Time Clock driver.\n");
return 0;
err_clk:
clk_disable_unprepare(sclk);
return ret;
}
/*
* Disable and remove the RTC driver
*/
static int __exit at91_rtc_remove(struct platform_device *pdev)
{
/* Disable all interrupts */
at91_rtc_write_idr(AT91_RTC_ACKUPD | AT91_RTC_ALARM |
AT91_RTC_SECEV | AT91_RTC_TIMEV |
AT91_RTC_CALEV);
clk_disable_unprepare(sclk);
return 0;
}
static void at91_rtc_shutdown(struct platform_device *pdev)
{
/* Disable all interrupts */
at91_rtc_write(AT91_RTC_IDR, AT91_RTC_ACKUPD | AT91_RTC_ALARM |
AT91_RTC_SECEV | AT91_RTC_TIMEV |
AT91_RTC_CALEV);
}
#ifdef CONFIG_PM_SLEEP
/* AT91RM9200 RTC Power management control */
static int at91_rtc_suspend(struct device *dev)
{
/* this IRQ is shared with DBGU and other hardware which isn't
* necessarily doing PM like we are...
*/
at91_rtc_write(AT91_RTC_SCCR, AT91_RTC_ALARM);
at91_rtc_imr = at91_rtc_read_imr()
& (AT91_RTC_ALARM|AT91_RTC_SECEV);
if (at91_rtc_imr) {
if (device_may_wakeup(dev)) {
unsigned long flags;
enable_irq_wake(irq);
spin_lock_irqsave(&suspended_lock, flags);
suspended = true;
spin_unlock_irqrestore(&suspended_lock, flags);
} else {
at91_rtc_write_idr(at91_rtc_imr);
}
}
return 0;
}
static int at91_rtc_resume(struct device *dev)
{
struct rtc_device *rtc = dev_get_drvdata(dev);
if (at91_rtc_imr) {
if (device_may_wakeup(dev)) {
unsigned long flags;
spin_lock_irqsave(&suspended_lock, flags);
if (cached_events) {
rtc_update_irq(rtc, 1, cached_events);
cached_events = 0;
}
suspended = false;
spin_unlock_irqrestore(&suspended_lock, flags);
disable_irq_wake(irq);
}
at91_rtc_write_ier(at91_rtc_imr);
}
return 0;
}
#endif
static SIMPLE_DEV_PM_OPS(at91_rtc_pm_ops, at91_rtc_suspend, at91_rtc_resume);
static struct platform_driver at91_rtc_driver = {
.remove = __exit_p(at91_rtc_remove),
.shutdown = at91_rtc_shutdown,
.driver = {
.name = "at91_rtc",
.pm = &at91_rtc_pm_ops,
.of_match_table = of_match_ptr(at91_rtc_dt_ids),
},
};
module_platform_driver_probe(at91_rtc_driver, at91_rtc_probe);
MODULE_AUTHOR("Rick Bronson");
MODULE_DESCRIPTION("RTC driver for Atmel AT91RM9200");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:at91_rtc");
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