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linux/drivers/rtc/rtc-wm831x.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+
/*
* Real Time Clock driver for Wolfson Microelectronics WM831x
*
* Copyright (C) 2009 Wolfson Microelectronics PLC.
*
* Author: Mark Brown <broonie@opensource.wolfsonmicro.com>
*
*/
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/time.h>
#include <linux/rtc.h>
#include <linux/slab.h>
#include <linux/bcd.h>
#include <linux/interrupt.h>
#include <linux/ioctl.h>
#include <linux/completion.h>
#include <linux/mfd/wm831x/core.h>
#include <linux/delay.h>
#include <linux/platform_device.h>
#include <linux/random.h>
/*
* R16416 (0x4020) - RTC Write Counter
*/
#define WM831X_RTC_WR_CNT_MASK 0xFFFF /* RTC_WR_CNT - [15:0] */
#define WM831X_RTC_WR_CNT_SHIFT 0 /* RTC_WR_CNT - [15:0] */
#define WM831X_RTC_WR_CNT_WIDTH 16 /* RTC_WR_CNT - [15:0] */
/*
* R16417 (0x4021) - RTC Time 1
*/
#define WM831X_RTC_TIME_MASK 0xFFFF /* RTC_TIME - [15:0] */
#define WM831X_RTC_TIME_SHIFT 0 /* RTC_TIME - [15:0] */
#define WM831X_RTC_TIME_WIDTH 16 /* RTC_TIME - [15:0] */
/*
* R16418 (0x4022) - RTC Time 2
*/
#define WM831X_RTC_TIME_MASK 0xFFFF /* RTC_TIME - [15:0] */
#define WM831X_RTC_TIME_SHIFT 0 /* RTC_TIME - [15:0] */
#define WM831X_RTC_TIME_WIDTH 16 /* RTC_TIME - [15:0] */
/*
* R16419 (0x4023) - RTC Alarm 1
*/
#define WM831X_RTC_ALM_MASK 0xFFFF /* RTC_ALM - [15:0] */
#define WM831X_RTC_ALM_SHIFT 0 /* RTC_ALM - [15:0] */
#define WM831X_RTC_ALM_WIDTH 16 /* RTC_ALM - [15:0] */
/*
* R16420 (0x4024) - RTC Alarm 2
*/
#define WM831X_RTC_ALM_MASK 0xFFFF /* RTC_ALM - [15:0] */
#define WM831X_RTC_ALM_SHIFT 0 /* RTC_ALM - [15:0] */
#define WM831X_RTC_ALM_WIDTH 16 /* RTC_ALM - [15:0] */
/*
* R16421 (0x4025) - RTC Control
*/
#define WM831X_RTC_VALID 0x8000 /* RTC_VALID */
#define WM831X_RTC_VALID_MASK 0x8000 /* RTC_VALID */
#define WM831X_RTC_VALID_SHIFT 15 /* RTC_VALID */
#define WM831X_RTC_VALID_WIDTH 1 /* RTC_VALID */
#define WM831X_RTC_SYNC_BUSY 0x4000 /* RTC_SYNC_BUSY */
#define WM831X_RTC_SYNC_BUSY_MASK 0x4000 /* RTC_SYNC_BUSY */
#define WM831X_RTC_SYNC_BUSY_SHIFT 14 /* RTC_SYNC_BUSY */
#define WM831X_RTC_SYNC_BUSY_WIDTH 1 /* RTC_SYNC_BUSY */
#define WM831X_RTC_ALM_ENA 0x0400 /* RTC_ALM_ENA */
#define WM831X_RTC_ALM_ENA_MASK 0x0400 /* RTC_ALM_ENA */
#define WM831X_RTC_ALM_ENA_SHIFT 10 /* RTC_ALM_ENA */
#define WM831X_RTC_ALM_ENA_WIDTH 1 /* RTC_ALM_ENA */
#define WM831X_RTC_PINT_FREQ_MASK 0x0070 /* RTC_PINT_FREQ - [6:4] */
#define WM831X_RTC_PINT_FREQ_SHIFT 4 /* RTC_PINT_FREQ - [6:4] */
#define WM831X_RTC_PINT_FREQ_WIDTH 3 /* RTC_PINT_FREQ - [6:4] */
/*
* R16422 (0x4026) - RTC Trim
*/
#define WM831X_RTC_TRIM_MASK 0x03FF /* RTC_TRIM - [9:0] */
#define WM831X_RTC_TRIM_SHIFT 0 /* RTC_TRIM - [9:0] */
#define WM831X_RTC_TRIM_WIDTH 10 /* RTC_TRIM - [9:0] */
#define WM831X_SET_TIME_RETRIES 5
#define WM831X_GET_TIME_RETRIES 5
struct wm831x_rtc {
struct wm831x *wm831x;
struct rtc_device *rtc;
unsigned int alarm_enabled:1;
};
static void wm831x_rtc_add_randomness(struct wm831x *wm831x)
{
int ret;
u16 reg;
/*
* The write counter contains a pseudo-random number which is
* regenerated every time we set the RTC so it should be a
* useful per-system source of entropy.
*/
ret = wm831x_reg_read(wm831x, WM831X_RTC_WRITE_COUNTER);
if (ret >= 0) {
reg = ret;
add_device_randomness(&reg, sizeof(reg));
} else {
dev_warn(wm831x->dev, "Failed to read RTC write counter: %d\n",
ret);
}
}
/*
* Read current time and date in RTC
*/
static int wm831x_rtc_readtime(struct device *dev, struct rtc_time *tm)
{
struct wm831x_rtc *wm831x_rtc = dev_get_drvdata(dev);
struct wm831x *wm831x = wm831x_rtc->wm831x;
u16 time1[2], time2[2];
int ret;
int count = 0;
/* Has the RTC been programmed? */
ret = wm831x_reg_read(wm831x, WM831X_RTC_CONTROL);
if (ret < 0) {
dev_err(dev, "Failed to read RTC control: %d\n", ret);
return ret;
}
if (!(ret & WM831X_RTC_VALID)) {
dev_dbg(dev, "RTC not yet configured\n");
return -EINVAL;
}
/* Read twice to make sure we don't read a corrupt, partially
* incremented, value.
*/
do {
ret = wm831x_bulk_read(wm831x, WM831X_RTC_TIME_1,
2, time1);
if (ret != 0)
continue;
ret = wm831x_bulk_read(wm831x, WM831X_RTC_TIME_1,
2, time2);
if (ret != 0)
continue;
if (memcmp(time1, time2, sizeof(time1)) == 0) {
u32 time = (time1[0] << 16) | time1[1];
rtc_time64_to_tm(time, tm);
return 0;
}
} while (++count < WM831X_GET_TIME_RETRIES);
dev_err(dev, "Timed out reading current time\n");
return -EIO;
}
/*
* Set current time and date in RTC
*/
static int wm831x_rtc_settime(struct device *dev, struct rtc_time *tm)
{
struct wm831x_rtc *wm831x_rtc = dev_get_drvdata(dev);
struct wm831x *wm831x = wm831x_rtc->wm831x;
struct rtc_time new_tm;
unsigned long time, new_time;
int ret;
int count = 0;
time = rtc_tm_to_time64(tm);
ret = wm831x_reg_write(wm831x, WM831X_RTC_TIME_1,
(time >> 16) & 0xffff);
if (ret < 0) {
dev_err(dev, "Failed to write TIME_1: %d\n", ret);
return ret;
}
ret = wm831x_reg_write(wm831x, WM831X_RTC_TIME_2, time & 0xffff);
if (ret < 0) {
dev_err(dev, "Failed to write TIME_2: %d\n", ret);
return ret;
}
/* Wait for the update to complete - should happen first time
* round but be conservative.
*/
do {
msleep(1);
ret = wm831x_reg_read(wm831x, WM831X_RTC_CONTROL);
if (ret < 0)
ret = WM831X_RTC_SYNC_BUSY;
} while (!(ret & WM831X_RTC_SYNC_BUSY) &&
++count < WM831X_SET_TIME_RETRIES);
if (ret & WM831X_RTC_SYNC_BUSY) {
dev_err(dev, "Timed out writing RTC update\n");
return -EIO;
}
/* Check that the update was accepted; security features may
* have caused the update to be ignored.
*/
ret = wm831x_rtc_readtime(dev, &new_tm);
if (ret < 0)
return ret;
new_time = rtc_tm_to_time64(&new_tm);
/* Allow a second of change in case of tick */
if (new_time - time > 1) {
dev_err(dev, "RTC update not permitted by hardware\n");
return -EPERM;
}
return 0;
}
/*
* Read alarm time and date in RTC
*/
static int wm831x_rtc_readalarm(struct device *dev, struct rtc_wkalrm *alrm)
{
struct wm831x_rtc *wm831x_rtc = dev_get_drvdata(dev);
int ret;
u16 data[2];
u32 time;
ret = wm831x_bulk_read(wm831x_rtc->wm831x, WM831X_RTC_ALARM_1,
2, data);
if (ret != 0) {
dev_err(dev, "Failed to read alarm time: %d\n", ret);
return ret;
}
time = (data[0] << 16) | data[1];
rtc_time64_to_tm(time, &alrm->time);
ret = wm831x_reg_read(wm831x_rtc->wm831x, WM831X_RTC_CONTROL);
if (ret < 0) {
dev_err(dev, "Failed to read RTC control: %d\n", ret);
return ret;
}
if (ret & WM831X_RTC_ALM_ENA)
alrm->enabled = 1;
else
alrm->enabled = 0;
return 0;
}
static int wm831x_rtc_stop_alarm(struct wm831x_rtc *wm831x_rtc)
{
wm831x_rtc->alarm_enabled = 0;
return wm831x_set_bits(wm831x_rtc->wm831x, WM831X_RTC_CONTROL,
WM831X_RTC_ALM_ENA, 0);
}
static int wm831x_rtc_start_alarm(struct wm831x_rtc *wm831x_rtc)
{
wm831x_rtc->alarm_enabled = 1;
return wm831x_set_bits(wm831x_rtc->wm831x, WM831X_RTC_CONTROL,
WM831X_RTC_ALM_ENA, WM831X_RTC_ALM_ENA);
}
static int wm831x_rtc_setalarm(struct device *dev, struct rtc_wkalrm *alrm)
{
struct wm831x_rtc *wm831x_rtc = dev_get_drvdata(dev);
struct wm831x *wm831x = wm831x_rtc->wm831x;
int ret;
unsigned long time;
time = rtc_tm_to_time64(&alrm->time);
ret = wm831x_rtc_stop_alarm(wm831x_rtc);
if (ret < 0) {
dev_err(dev, "Failed to stop alarm: %d\n", ret);
return ret;
}
ret = wm831x_reg_write(wm831x, WM831X_RTC_ALARM_1,
(time >> 16) & 0xffff);
if (ret < 0) {
dev_err(dev, "Failed to write ALARM_1: %d\n", ret);
return ret;
}
ret = wm831x_reg_write(wm831x, WM831X_RTC_ALARM_2, time & 0xffff);
if (ret < 0) {
dev_err(dev, "Failed to write ALARM_2: %d\n", ret);
return ret;
}
if (alrm->enabled) {
ret = wm831x_rtc_start_alarm(wm831x_rtc);
if (ret < 0) {
dev_err(dev, "Failed to start alarm: %d\n", ret);
return ret;
}
}
return 0;
}
static int wm831x_rtc_alarm_irq_enable(struct device *dev,
unsigned int enabled)
{
struct wm831x_rtc *wm831x_rtc = dev_get_drvdata(dev);
if (enabled)
return wm831x_rtc_start_alarm(wm831x_rtc);
else
return wm831x_rtc_stop_alarm(wm831x_rtc);
}
static irqreturn_t wm831x_alm_irq(int irq, void *data)
{
struct wm831x_rtc *wm831x_rtc = data;
rtc_update_irq(wm831x_rtc->rtc, 1, RTC_IRQF | RTC_AF);
return IRQ_HANDLED;
}
static const struct rtc_class_ops wm831x_rtc_ops = {
.read_time = wm831x_rtc_readtime,
.set_time = wm831x_rtc_settime,
.read_alarm = wm831x_rtc_readalarm,
.set_alarm = wm831x_rtc_setalarm,
.alarm_irq_enable = wm831x_rtc_alarm_irq_enable,
};
#ifdef CONFIG_PM
/* Turn off the alarm if it should not be a wake source. */
static int wm831x_rtc_suspend(struct device *dev)
{
struct wm831x_rtc *wm831x_rtc = dev_get_drvdata(dev);
int ret, enable;
if (wm831x_rtc->alarm_enabled && device_may_wakeup(dev))
enable = WM831X_RTC_ALM_ENA;
else
enable = 0;
ret = wm831x_set_bits(wm831x_rtc->wm831x, WM831X_RTC_CONTROL,
WM831X_RTC_ALM_ENA, enable);
if (ret != 0)
dev_err(dev, "Failed to update RTC alarm: %d\n", ret);
return 0;
}
/* Enable the alarm if it should be enabled (in case it was disabled to
* prevent use as a wake source).
*/
static int wm831x_rtc_resume(struct device *dev)
{
struct wm831x_rtc *wm831x_rtc = dev_get_drvdata(dev);
int ret;
if (wm831x_rtc->alarm_enabled) {
ret = wm831x_rtc_start_alarm(wm831x_rtc);
if (ret != 0)
dev_err(dev, "Failed to restart RTC alarm: %d\n", ret);
}
return 0;
}
/* Unconditionally disable the alarm */
static int wm831x_rtc_freeze(struct device *dev)
{
struct wm831x_rtc *wm831x_rtc = dev_get_drvdata(dev);
int ret;
ret = wm831x_set_bits(wm831x_rtc->wm831x, WM831X_RTC_CONTROL,
WM831X_RTC_ALM_ENA, 0);
if (ret != 0)
dev_err(dev, "Failed to stop RTC alarm: %d\n", ret);
return 0;
}
#else
#define wm831x_rtc_suspend NULL
#define wm831x_rtc_resume NULL
#define wm831x_rtc_freeze NULL
#endif
static int wm831x_rtc_probe(struct platform_device *pdev)
{
struct wm831x *wm831x = dev_get_drvdata(pdev->dev.parent);
struct wm831x_rtc *wm831x_rtc;
int alm_irq = wm831x_irq(wm831x, platform_get_irq_byname(pdev, "ALM"));
int ret = 0;
wm831x_rtc = devm_kzalloc(&pdev->dev, sizeof(*wm831x_rtc), GFP_KERNEL);
if (wm831x_rtc == NULL)
return -ENOMEM;
platform_set_drvdata(pdev, wm831x_rtc);
wm831x_rtc->wm831x = wm831x;
ret = wm831x_reg_read(wm831x, WM831X_RTC_CONTROL);
if (ret < 0) {
dev_err(&pdev->dev, "Failed to read RTC control: %d\n", ret);
return ret;
}
if (ret & WM831X_RTC_ALM_ENA)
wm831x_rtc->alarm_enabled = 1;
device_init_wakeup(&pdev->dev, 1);
wm831x_rtc->rtc = devm_rtc_allocate_device(&pdev->dev);
if (IS_ERR(wm831x_rtc->rtc))
return PTR_ERR(wm831x_rtc->rtc);
wm831x_rtc->rtc->ops = &wm831x_rtc_ops;
wm831x_rtc->rtc->range_max = U32_MAX;
ret = devm_rtc_register_device(wm831x_rtc->rtc);
if (ret)
return ret;
ret = devm_request_threaded_irq(&pdev->dev, alm_irq, NULL,
wm831x_alm_irq,
IRQF_TRIGGER_RISING | IRQF_ONESHOT,
"RTC alarm",
wm831x_rtc);
if (ret != 0) {
dev_err(&pdev->dev, "Failed to request alarm IRQ %d: %d\n",
alm_irq, ret);
}
wm831x_rtc_add_randomness(wm831x);
return 0;
}
static const struct dev_pm_ops wm831x_rtc_pm_ops = {
.suspend = wm831x_rtc_suspend,
.resume = wm831x_rtc_resume,
.freeze = wm831x_rtc_freeze,
.thaw = wm831x_rtc_resume,
.restore = wm831x_rtc_resume,
.poweroff = wm831x_rtc_suspend,
};
static struct platform_driver wm831x_rtc_driver = {
.probe = wm831x_rtc_probe,
.driver = {
.name = "wm831x-rtc",
.pm = &wm831x_rtc_pm_ops,
},
};
module_platform_driver(wm831x_rtc_driver);
MODULE_AUTHOR("Mark Brown <broonie@opensource.wolfsonmicro.com>");
MODULE_DESCRIPTION("RTC driver for the WM831x series PMICs");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:wm831x-rtc");
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