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linux/drivers/rtc/rtc-sun6i.c
Chen-Yu Tsai 9765d2d943 rtc: sun6i: Add sun6i RTC driver 
This patch introduces the driver for the RTC in the Allwinner A31 and
A23 SoCs.

Unlike the RTC found in A10/A20 SoCs, which was part of the timer, the
RTC in A31/A23 are a separate hardware block, which also contain a few
controls for the RTC block hardware (a regulator and RTC block GPIO pin
latches), while also having separate interrupts for the alarms.

The hardware is different enough to make a different driver for it.

Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Reviewed-by: Varka Bhadram <varkabhadram@gmail.com>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
2014-09-19 12:39:19 +02:00

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/*
* An RTC driver for Allwinner A31/A23
*
* Copyright (c) 2014, Chen-Yu Tsai <wens@csie.org>
*
* based on rtc-sunxi.c
*
* An RTC driver for Allwinner A10/A20
*
* Copyright (c) 2013, Carlo Caione <carlo.caione@gmail.com>
*
* 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/delay.h>
#include <linux/err.h>
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/of_device.h>
#include <linux/platform_device.h>
#include <linux/rtc.h>
#include <linux/types.h>
/* Control register */
#define SUN6I_LOSC_CTRL 0x0000
#define SUN6I_LOSC_CTRL_ALM_DHMS_ACC BIT(9)
#define SUN6I_LOSC_CTRL_RTC_HMS_ACC BIT(8)
#define SUN6I_LOSC_CTRL_RTC_YMD_ACC BIT(7)
#define SUN6I_LOSC_CTRL_ACC_MASK GENMASK(9, 7)
/* RTC */
#define SUN6I_RTC_YMD 0x0010
#define SUN6I_RTC_HMS 0x0014
/* Alarm 0 (counter) */
#define SUN6I_ALRM_COUNTER 0x0020
#define SUN6I_ALRM_CUR_VAL 0x0024
#define SUN6I_ALRM_EN 0x0028
#define SUN6I_ALRM_EN_CNT_EN BIT(0)
#define SUN6I_ALRM_IRQ_EN 0x002c
#define SUN6I_ALRM_IRQ_EN_CNT_IRQ_EN BIT(0)
#define SUN6I_ALRM_IRQ_STA 0x0030
#define SUN6I_ALRM_IRQ_STA_CNT_IRQ_PEND BIT(0)
/* Alarm 1 (wall clock) */
#define SUN6I_ALRM1_EN 0x0044
#define SUN6I_ALRM1_IRQ_EN 0x0048
#define SUN6I_ALRM1_IRQ_STA 0x004c
#define SUN6I_ALRM1_IRQ_STA_WEEK_IRQ_PEND BIT(0)
/* Alarm config */
#define SUN6I_ALARM_CONFIG 0x0050
#define SUN6I_ALARM_CONFIG_WAKEUP BIT(0)
/*
* Get date values
*/
#define SUN6I_DATE_GET_DAY_VALUE(x) ((x) & 0x0000001f)
#define SUN6I_DATE_GET_MON_VALUE(x) (((x) & 0x00000f00) >> 8)
#define SUN6I_DATE_GET_YEAR_VALUE(x) (((x) & 0x003f0000) >> 16)
#define SUN6I_LEAP_GET_VALUE(x) (((x) & 0x00400000) >> 22)
/*
* Get time values
*/
#define SUN6I_TIME_GET_SEC_VALUE(x) ((x) & 0x0000003f)
#define SUN6I_TIME_GET_MIN_VALUE(x) (((x) & 0x00003f00) >> 8)
#define SUN6I_TIME_GET_HOUR_VALUE(x) (((x) & 0x001f0000) >> 16)
/*
* Set date values
*/
#define SUN6I_DATE_SET_DAY_VALUE(x) ((x) & 0x0000001f)
#define SUN6I_DATE_SET_MON_VALUE(x) ((x) << 8 & 0x00000f00)
#define SUN6I_DATE_SET_YEAR_VALUE(x) ((x) << 16 & 0x003f0000)
#define SUN6I_LEAP_SET_VALUE(x) ((x) << 22 & 0x00400000)
/*
* Set time values
*/
#define SUN6I_TIME_SET_SEC_VALUE(x) ((x) & 0x0000003f)
#define SUN6I_TIME_SET_MIN_VALUE(x) ((x) << 8 & 0x00003f00)
#define SUN6I_TIME_SET_HOUR_VALUE(x) ((x) << 16 & 0x001f0000)
/*
* The year parameter passed to the driver is usually an offset relative to
* the year 1900. This macro is used to convert this offset to another one
* relative to the minimum year allowed by the hardware.
*
* The year range is 1970 - 2033. This range is selected to match Allwinner's
* driver, even though it is somewhat limited.
*/
#define SUN6I_YEAR_MIN 1970
#define SUN6I_YEAR_MAX 2033
#define SUN6I_YEAR_OFF (SUN6I_YEAR_MIN - 1900)
struct sun6i_rtc_dev {
struct rtc_device *rtc;
struct device *dev;
void __iomem *base;
int irq;
unsigned long alarm;
};
static irqreturn_t sun6i_rtc_alarmirq(int irq, void *id)
{
struct sun6i_rtc_dev *chip = (struct sun6i_rtc_dev *) id;
u32 val;
val = readl(chip->base + SUN6I_ALRM_IRQ_STA);
if (val & SUN6I_ALRM_IRQ_STA_CNT_IRQ_PEND) {
val |= SUN6I_ALRM_IRQ_STA_CNT_IRQ_PEND;
writel(val, chip->base + SUN6I_ALRM_IRQ_STA);
rtc_update_irq(chip->rtc, 1, RTC_AF | RTC_IRQF);
return IRQ_HANDLED;
}
return IRQ_NONE;
}
static void sun6i_rtc_setaie(int to, struct sun6i_rtc_dev *chip)
{
u32 alrm_val = 0;
u32 alrm_irq_val = 0;
u32 alrm_wake_val = 0;
if (to) {
alrm_val = SUN6I_ALRM_EN_CNT_EN;
alrm_irq_val = SUN6I_ALRM_IRQ_EN_CNT_IRQ_EN;
alrm_wake_val = SUN6I_ALARM_CONFIG_WAKEUP;
} else {
writel(SUN6I_ALRM_IRQ_STA_CNT_IRQ_PEND,
chip->base + SUN6I_ALRM_IRQ_STA);
}
writel(alrm_val, chip->base + SUN6I_ALRM_EN);
writel(alrm_irq_val, chip->base + SUN6I_ALRM_IRQ_EN);
writel(alrm_wake_val, chip->base + SUN6I_ALARM_CONFIG);
}
static int sun6i_rtc_gettime(struct device *dev, struct rtc_time *rtc_tm)
{
struct sun6i_rtc_dev *chip = dev_get_drvdata(dev);
u32 date, time;
/*
* read again in case it changes
*/
do {
date = readl(chip->base + SUN6I_RTC_YMD);
time = readl(chip->base + SUN6I_RTC_HMS);
} while ((date != readl(chip->base + SUN6I_RTC_YMD)) ||
(time != readl(chip->base + SUN6I_RTC_HMS)));
rtc_tm->tm_sec = SUN6I_TIME_GET_SEC_VALUE(time);
rtc_tm->tm_min = SUN6I_TIME_GET_MIN_VALUE(time);
rtc_tm->tm_hour = SUN6I_TIME_GET_HOUR_VALUE(time);
rtc_tm->tm_mday = SUN6I_DATE_GET_DAY_VALUE(date);
rtc_tm->tm_mon = SUN6I_DATE_GET_MON_VALUE(date);
rtc_tm->tm_year = SUN6I_DATE_GET_YEAR_VALUE(date);
rtc_tm->tm_mon -= 1;
/*
* switch from (data_year->min)-relative offset to
* a (1900)-relative one
*/
rtc_tm->tm_year += SUN6I_YEAR_OFF;
return rtc_valid_tm(rtc_tm);
}
static int sun6i_rtc_getalarm(struct device *dev, struct rtc_wkalrm *wkalrm)
{
struct sun6i_rtc_dev *chip = dev_get_drvdata(dev);
u32 alrm_st;
u32 alrm_en;
alrm_en = readl(chip->base + SUN6I_ALRM_IRQ_EN);
alrm_st = readl(chip->base + SUN6I_ALRM_IRQ_STA);
wkalrm->enabled = !!(alrm_en & SUN6I_ALRM_EN_CNT_EN);
wkalrm->pending = !!(alrm_st & SUN6I_ALRM_EN_CNT_EN);
rtc_time_to_tm(chip->alarm, &wkalrm->time);
return 0;
}
static int sun6i_rtc_setalarm(struct device *dev, struct rtc_wkalrm *wkalrm)
{
struct sun6i_rtc_dev *chip = dev_get_drvdata(dev);
struct rtc_time *alrm_tm = &wkalrm->time;
struct rtc_time tm_now;
unsigned long time_now = 0;
unsigned long time_set = 0;
unsigned long time_gap = 0;
int ret = 0;
ret = sun6i_rtc_gettime(dev, &tm_now);
if (ret < 0) {
dev_err(dev, "Error in getting time\n");
return -EINVAL;
}
rtc_tm_to_time(alrm_tm, &time_set);
rtc_tm_to_time(&tm_now, &time_now);
if (time_set <= time_now) {
dev_err(dev, "Date to set in the past\n");
return -EINVAL;
}
time_gap = time_set - time_now;
if (time_gap > U32_MAX) {
dev_err(dev, "Date too far in the future\n");
return -EINVAL;
}
sun6i_rtc_setaie(0, chip);
writel(0, chip->base + SUN6I_ALRM_COUNTER);
usleep_range(100, 300);
writel(time_gap, chip->base + SUN6I_ALRM_COUNTER);
chip->alarm = time_set;
sun6i_rtc_setaie(wkalrm->enabled, chip);
return 0;
}
static int sun6i_rtc_wait(struct sun6i_rtc_dev *chip, int offset,
unsigned int mask, unsigned int ms_timeout)
{
const unsigned long timeout = jiffies + msecs_to_jiffies(ms_timeout);
u32 reg;
do {
reg = readl(chip->base + offset);
reg &= mask;
if (!reg)
return 0;
} while (time_before(jiffies, timeout));
return -ETIMEDOUT;
}
static int sun6i_rtc_settime(struct device *dev, struct rtc_time *rtc_tm)
{
struct sun6i_rtc_dev *chip = dev_get_drvdata(dev);
u32 date = 0;
u32 time = 0;
int year;
year = rtc_tm->tm_year + 1900;
if (year < SUN6I_YEAR_MIN || year > SUN6I_YEAR_MAX) {
dev_err(dev, "rtc only supports year in range %d - %d\n",
SUN6I_YEAR_MIN, SUN6I_YEAR_MAX);
return -EINVAL;
}
rtc_tm->tm_year -= SUN6I_YEAR_OFF;
rtc_tm->tm_mon += 1;
date = SUN6I_DATE_SET_DAY_VALUE(rtc_tm->tm_mday) |
SUN6I_DATE_SET_MON_VALUE(rtc_tm->tm_mon) |
SUN6I_DATE_SET_YEAR_VALUE(rtc_tm->tm_year);
if (is_leap_year(year))
date |= SUN6I_LEAP_SET_VALUE(1);
time = SUN6I_TIME_SET_SEC_VALUE(rtc_tm->tm_sec) |
SUN6I_TIME_SET_MIN_VALUE(rtc_tm->tm_min) |
SUN6I_TIME_SET_HOUR_VALUE(rtc_tm->tm_hour);
/* Check whether registers are writable */
if (sun6i_rtc_wait(chip, SUN6I_LOSC_CTRL,
SUN6I_LOSC_CTRL_ACC_MASK, 50)) {
dev_err(dev, "rtc is still busy.\n");
return -EBUSY;
}
writel(time, chip->base + SUN6I_RTC_HMS);
/*
* After writing the RTC HH-MM-SS register, the
* SUN6I_LOSC_CTRL_RTC_HMS_ACC bit is set and it will not
* be cleared until the real writing operation is finished
*/
if (sun6i_rtc_wait(chip, SUN6I_LOSC_CTRL,
SUN6I_LOSC_CTRL_RTC_HMS_ACC, 50)) {
dev_err(dev, "Failed to set rtc time.\n");
return -ETIMEDOUT;
}
writel(date, chip->base + SUN6I_RTC_YMD);
/*
* After writing the RTC YY-MM-DD register, the
* SUN6I_LOSC_CTRL_RTC_YMD_ACC bit is set and it will not
* be cleared until the real writing operation is finished
*/
if (sun6i_rtc_wait(chip, SUN6I_LOSC_CTRL,
SUN6I_LOSC_CTRL_RTC_YMD_ACC, 50)) {
dev_err(dev, "Failed to set rtc time.\n");
return -ETIMEDOUT;
}
return 0;
}
static int sun6i_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
{
struct sun6i_rtc_dev *chip = dev_get_drvdata(dev);
if (!enabled)
sun6i_rtc_setaie(enabled, chip);
return 0;
}
static const struct rtc_class_ops sun6i_rtc_ops = {
.read_time = sun6i_rtc_gettime,
.set_time = sun6i_rtc_settime,
.read_alarm = sun6i_rtc_getalarm,
.set_alarm = sun6i_rtc_setalarm,
.alarm_irq_enable = sun6i_rtc_alarm_irq_enable
};
static int sun6i_rtc_probe(struct platform_device *pdev)
{
struct sun6i_rtc_dev *chip;
struct resource *res;
int ret;
chip = devm_kzalloc(&pdev->dev, sizeof(*chip), GFP_KERNEL);
if (!chip)
return -ENOMEM;
platform_set_drvdata(pdev, chip);
chip->dev = &pdev->dev;
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
chip->base = devm_ioremap_resource(&pdev->dev, res);
if (IS_ERR(chip->base))
return PTR_ERR(chip->base);
chip->irq = platform_get_irq(pdev, 0);
if (chip->irq < 0) {
dev_err(&pdev->dev, "No IRQ resource\n");
return chip->irq;
}
ret = devm_request_irq(&pdev->dev, chip->irq, sun6i_rtc_alarmirq,
0, dev_name(&pdev->dev), chip);
if (ret) {
dev_err(&pdev->dev, "Could not request IRQ\n");
return ret;
}
/* clear the alarm counter value */
writel(0, chip->base + SUN6I_ALRM_COUNTER);
/* disable counter alarm */
writel(0, chip->base + SUN6I_ALRM_EN);
/* disable counter alarm interrupt */
writel(0, chip->base + SUN6I_ALRM_IRQ_EN);
/* disable week alarm */
writel(0, chip->base + SUN6I_ALRM1_EN);
/* disable week alarm interrupt */
writel(0, chip->base + SUN6I_ALRM1_IRQ_EN);
/* clear counter alarm pending interrupts */
writel(SUN6I_ALRM_IRQ_STA_CNT_IRQ_PEND,
chip->base + SUN6I_ALRM_IRQ_STA);
/* clear week alarm pending interrupts */
writel(SUN6I_ALRM1_IRQ_STA_WEEK_IRQ_PEND,
chip->base + SUN6I_ALRM1_IRQ_STA);
/* disable alarm wakeup */
writel(0, chip->base + SUN6I_ALARM_CONFIG);
chip->rtc = rtc_device_register("rtc-sun6i", &pdev->dev,
&sun6i_rtc_ops, THIS_MODULE);
if (IS_ERR(chip->rtc)) {
dev_err(&pdev->dev, "unable to register device\n");
return PTR_ERR(chip->rtc);
}
dev_info(&pdev->dev, "RTC enabled\n");
return 0;
}
static int sun6i_rtc_remove(struct platform_device *pdev)
{
struct sun6i_rtc_dev *chip = platform_get_drvdata(pdev);
rtc_device_unregister(chip->rtc);
return 0;
}
static const struct of_device_id sun6i_rtc_dt_ids[] = {
{ .compatible = "allwinner,sun6i-a31-rtc" },
{ /* sentinel */ },
};
MODULE_DEVICE_TABLE(of, sun6i_rtc_dt_ids);
static struct platform_driver sun6i_rtc_driver = {
.probe = sun6i_rtc_probe,
.remove = sun6i_rtc_remove,
.driver = {
.name = "sun6i-rtc",
.of_match_table = sun6i_rtc_dt_ids,
},
};
module_platform_driver(sun6i_rtc_driver);
MODULE_DESCRIPTION("sun6i RTC driver");
MODULE_AUTHOR("Chen-Yu Tsai <wens@csie.org>");
MODULE_LICENSE("GPL");
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