/*
* An RTC driver for the NVIDIA Tegra 200 series internal RTC.
*
* Copyright (c) 2010, NVIDIA Corporation.
*
* 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.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/io.h>
#include <linux/irq.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/pm.h>
#include <linux/rtc.h>
#include <linux/slab.h>
/* set to 1 = busy every eight 32kHz clocks during copy of sec+msec to AHB */
#define TEGRA_RTC_REG_BUSY 0x004
#define TEGRA_RTC_REG_SECONDS 0x008
/* when msec is read, the seconds are buffered into shadow seconds. */
#define TEGRA_RTC_REG_SHADOW_SECONDS 0x00c
#define TEGRA_RTC_REG_MILLI_SECONDS 0x010
#define TEGRA_RTC_REG_SECONDS_ALARM0 0x014
#define TEGRA_RTC_REG_SECONDS_ALARM1 0x018
#define TEGRA_RTC_REG_MILLI_SECONDS_ALARM0 0x01c
#define TEGRA_RTC_REG_INTR_MASK 0x028
/* write 1 bits to clear status bits */
#define TEGRA_RTC_REG_INTR_STATUS 0x02c
/* bits in INTR_MASK */
#define TEGRA_RTC_INTR_MASK_MSEC_CDN_ALARM (1<<4)
#define TEGRA_RTC_INTR_MASK_SEC_CDN_ALARM (1<<3)
#define TEGRA_RTC_INTR_MASK_MSEC_ALARM (1<<2)
#define TEGRA_RTC_INTR_MASK_SEC_ALARM1 (1<<1)
#define TEGRA_RTC_INTR_MASK_SEC_ALARM0 (1<<0)
/* bits in INTR_STATUS */
#define TEGRA_RTC_INTR_STATUS_MSEC_CDN_ALARM (1<<4)
#define TEGRA_RTC_INTR_STATUS_SEC_CDN_ALARM (1<<3)
#define TEGRA_RTC_INTR_STATUS_MSEC_ALARM (1<<2)
#define TEGRA_RTC_INTR_STATUS_SEC_ALARM1 (1<<1)
#define TEGRA_RTC_INTR_STATUS_SEC_ALARM0 (1<<0)
struct tegra_rtc_info {
struct platform_device *pdev;
struct rtc_device *rtc_dev;
void __iomem *rtc_base; /* NULL if not initialized. */
struct clk *clk;
int tegra_rtc_irq; /* alarm and periodic irq */
spinlock_t tegra_rtc_lock;
};
/* RTC hardware is busy when it is updating its values over AHB once
* every eight 32kHz clocks (~250uS).
* outside of these updates the CPU is free to write.
* CPU is always free to read.
*/
static inline u32 tegra_rtc_check_busy(struct tegra_rtc_info *info)
{
return readl(info->rtc_base + TEGRA_RTC_REG_BUSY) & 1;
}
/* Wait for hardware to be ready for writing.
* This function tries to maximize the amount of time before the next update.
* It does this by waiting for the RTC to become busy with its periodic update,
* then returning once the RTC first becomes not busy.
* This periodic update (where the seconds and milliseconds are copied to the
* AHB side) occurs every eight 32kHz clocks (~250uS).
* The behavior of this function allows us to make some assumptions without
* introducing a race, because 250uS is plenty of time to read/write a value.
*/
static int tegra_rtc_wait_while_busy(struct device *dev)
{
struct tegra_rtc_info *info = dev_get_drvdata(dev);
int retries = 500; /* ~490 us is the worst case, ~250 us is best. */
/* first wait for the RTC to become busy. this is when it
* posts its updated seconds+msec registers to AHB side. */
while (tegra_rtc_check_busy(info)) {
if (!retries--)
goto retry_failed;
udelay(1);
}
/* now we have about 250 us to manipulate registers */
return 0;
retry_failed:
dev_err(dev, "write failed:retry count exceeded.\n");
return -ETIMEDOUT;
}
static int tegra_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
struct tegra_rtc_info *info = dev_get_drvdata(dev);
unsigned long sec, msec;
unsigned long sl_irq_flags;
/* RTC hardware copies seconds to shadow seconds when a read
* of milliseconds occurs. use a lock to keep other threads out. */
spin_lock_irqsave(&info->tegra_rtc_lock, sl_irq_flags);
msec = readl(info->rtc_base + TEGRA_RTC_REG_MILLI_SECONDS);
sec = readl(info->rtc_base + TEGRA_RTC_REG_SHADOW_SECONDS);
spin_unlock_irqrestore(&info->tegra_rtc_lock, sl_irq_flags);
rtc_time_to_tm(sec, tm);
dev_vdbg(dev, "time read as %lu. %d/%d/%d %d:%02u:%02u\n",
sec,
tm->tm_mon + 1,
tm->tm_mday,
tm->tm_year + 1900,
tm->tm_hour,
tm->tm_min,
tm->tm_sec
);
return 0;
}
static int tegra_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
struct tegra_rtc_info *info = dev_get_drvdata(dev);
unsigned long sec;
int ret;
/* convert tm to seconds. */
ret = rtc_valid_tm(tm);
if (ret)
return ret;
rtc_tm_to_time(tm, &sec);
dev_vdbg(dev, "time set to %lu. %d/%d/%d %d:%02u:%02u\n",
sec,
tm->tm_mon+1,
tm->tm_mday,
tm->tm_year+1900,
tm->tm_hour,
tm->tm_min,
tm->tm_sec
);
/* seconds only written if wait succeeded. */
ret = tegra_rtc_wait_while_busy(dev);
if (!ret)
writel(sec, info->rtc_base + TEGRA_RTC_REG_SECONDS);
dev_vdbg(dev, "time read back as %d\n",
readl(info->rtc_base + TEGRA_RTC_REG_SECONDS));
return ret;
}
static int tegra_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
{
struct tegra_rtc_info *info = dev_get_drvdata(dev);
unsigned long sec;
unsigned tmp;
sec = readl(info->rtc_base + TEGRA_RTC_REG_SECONDS_ALARM0);
if (sec == 0) {
/* alarm is disabled. */
alarm->enabled = 0;
} else {
/* alarm is enabled. */
alarm->enabled = 1;
rtc_time_to_tm(sec, &alarm->time);
}
tmp = readl(info->rtc_base + TEGRA_RTC_REG_INTR_STATUS);
alarm->pending = (tmp & TEGRA_RTC_INTR_STATUS_SEC_ALARM0) != 0;
return 0;
}
static int tegra_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
{
struct tegra_rtc_info *info = dev_get_drvdata(dev);
unsigned status;
unsigned long sl_irq_flags;
tegra_rtc_wait_while_busy(dev);
spin_lock_irqsave(&info->tegra_rtc_lock, sl_irq_flags);
/* read the original value, and OR in the flag. */
status = readl(info->rtc_base + TEGRA_RTC_REG_INTR_MASK);
if (enabled)
status |= TEGRA_RTC_INTR_MASK_SEC_ALARM0; /* set it */
else
status &= ~TEGRA_RTC_INTR_MASK_SEC_ALARM0; /* clear it */
writel(status, info->rtc_base + TEGRA_RTC_REG_INTR_MASK);
spin_unlock_irqrestore(&info->tegra_rtc_lock, sl_irq_flags);
return 0;
}
static int tegra_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
{
struct tegra_rtc_info *info = dev_get_drvdata(dev);
unsigned long sec;
if (alarm->enabled)
rtc_tm_to_time(&alarm->time, &sec);
else
sec = 0;
tegra_rtc_wait_while_busy(dev);
writel(sec, info->rtc_base + TEGRA_RTC_REG_SECONDS_ALARM0);
dev_vdbg(dev, "alarm read back as %d\n",
readl(info->rtc_base + TEGRA_RTC_REG_SECONDS_ALARM0));
/* if successfully written and alarm is enabled ... */
if (sec) {
tegra_rtc_alarm_irq_enable(dev, 1);
dev_vdbg(dev, "alarm set as %lu. %d/%d/%d %d:%02u:%02u\n",
sec,
alarm->time.tm_mon+1,
alarm->time.tm_mday,
alarm->time.tm_year+1900,
alarm->time.tm_hour,
alarm->time.tm_min,
alarm->time.tm_sec);
} else {
/* disable alarm if 0 or write error. */
dev_vdbg(dev, "alarm disabled\n");
tegra_rtc_alarm_irq_enable(dev, 0);
}
return 0;
}
static int tegra_rtc_proc(struct device *dev, struct seq_file *seq)
{
if (!dev || !dev->driver)
return 0;
seq_printf(seq, "name\t\t: %s\n", dev_name(dev));
return 0;
}
static irqreturn_t tegra_rtc_irq_handler(int irq, void *data)
{
struct device *dev = data;
struct tegra_rtc_info *info = dev_get_drvdata(dev);
unsigned long events = 0;
unsigned status;
unsigned long sl_irq_flags;
status = readl(info->rtc_base + TEGRA_RTC_REG_INTR_STATUS);
if (status) {
/* clear the interrupt masks and status on any irq. */
tegra_rtc_wait_while_busy(dev);
spin_lock_irqsave(&info->tegra_rtc_lock, sl_irq_flags);
writel(0, info->rtc_base + TEGRA_RTC_REG_INTR_MASK);
writel(status, info->rtc_base + TEGRA_RTC_REG_INTR_STATUS);
spin_unlock_irqrestore(&info->tegra_rtc_lock, sl_irq_flags);
}
/* check if Alarm */
if ((status & TEGRA_RTC_INTR_STATUS_SEC_ALARM0))
events |= RTC_IRQF | RTC_AF;
/* check if Periodic */
if ((status & TEGRA_RTC_INTR_STATUS_SEC_CDN_ALARM))
events |= RTC_IRQF | RTC_PF;
rtc_update_irq(info->rtc_dev, 1, events);
return IRQ_HANDLED;
}
static const struct rtc_class_ops tegra_rtc_ops = {
.read_time = tegra_rtc_read_time,
.set_time = tegra_rtc_set_time,
.read_alarm = tegra_rtc_read_alarm,
.set_alarm = tegra_rtc_set_alarm,
.proc = tegra_rtc_proc,
.alarm_irq_enable = tegra_rtc_alarm_irq_enable,
};
static const struct of_device_id tegra_rtc_dt_match[] = {
{ .compatible = "nvidia,tegra20-rtc", },
{}
};
MODULE_DEVICE_TABLE(of, tegra_rtc_dt_match);
static int __init tegra_rtc_probe(struct platform_device *pdev)
{
struct tegra_rtc_info *info;
struct resource *res;
int ret;
info = devm_kzalloc(&pdev->dev, sizeof(struct tegra_rtc_info),
GFP_KERNEL);
if (!info)
return -ENOMEM;
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
info->rtc_base = devm_ioremap_resource(&pdev->dev, res);
if (IS_ERR(info->rtc_base))
return PTR_ERR(info->rtc_base);
info->tegra_rtc_irq = platform_get_irq(pdev, 0);
if (info->tegra_rtc_irq <= 0)
return -EBUSY;
info->clk = devm_clk_get(&pdev->dev, NULL);
if (IS_ERR(info->clk))
return PTR_ERR(info->clk);
ret = clk_prepare_enable(info->clk);
if (ret < 0)
return ret;
/* set context info. */
info->pdev = pdev;
spin_lock_init(&info->tegra_rtc_lock);
platform_set_drvdata(pdev, info);
/* clear out the hardware. */
writel(0, info->rtc_base + TEGRA_RTC_REG_SECONDS_ALARM0);
writel(0xffffffff, info->rtc_base + TEGRA_RTC_REG_INTR_STATUS);
writel(0, info->rtc_base + TEGRA_RTC_REG_INTR_MASK);
device_init_wakeup(&pdev->dev, 1);
info->rtc_dev = devm_rtc_device_register(&pdev->dev,
dev_name(&pdev->dev), &tegra_rtc_ops,
THIS_MODULE);
if (IS_ERR(info->rtc_dev)) {
ret = PTR_ERR(info->rtc_dev);
dev_err(&pdev->dev, "Unable to register device (err=%d).\n",
ret);
goto disable_clk;
}
ret = devm_request_irq(&pdev->dev, info->tegra_rtc_irq,
tegra_rtc_irq_handler, IRQF_TRIGGER_HIGH,
dev_name(&pdev->dev), &pdev->dev);
if (ret) {
dev_err(&pdev->dev,
"Unable to request interrupt for device (err=%d).\n",
ret);
goto disable_clk;
}
dev_notice(&pdev->dev, "Tegra internal Real Time Clock\n");
return 0;
disable_clk:
clk_disable_unprepare(info->clk);
return ret;
}
static int tegra_rtc_remove(struct platform_device *pdev)
{
struct tegra_rtc_info *info = platform_get_drvdata(pdev);
clk_disable_unprepare(info->clk);
return 0;
}
#ifdef CONFIG_PM_SLEEP
static int tegra_rtc_suspend(struct device *dev)
{
struct tegra_rtc_info *info = dev_get_drvdata(dev);
tegra_rtc_wait_while_busy(dev);
/* only use ALARM0 as a wake source. */
writel(0xffffffff, info->rtc_base + TEGRA_RTC_REG_INTR_STATUS);
writel(TEGRA_RTC_INTR_STATUS_SEC_ALARM0,
info->rtc_base + TEGRA_RTC_REG_INTR_MASK);
dev_vdbg(dev, "alarm sec = %d\n",
readl(info->rtc_base + TEGRA_RTC_REG_SECONDS_ALARM0));
dev_vdbg(dev, "Suspend (device_may_wakeup=%d) irq:%d\n",
device_may_wakeup(dev), info->tegra_rtc_irq);
/* leave the alarms on as a wake source. */
if (device_may_wakeup(dev))
enable_irq_wake(info->tegra_rtc_irq);
return 0;
}
static int tegra_rtc_resume(struct device *dev)
{
struct tegra_rtc_info *info = dev_get_drvdata(dev);
dev_vdbg(dev, "Resume (device_may_wakeup=%d)\n",
device_may_wakeup(dev));
/* alarms were left on as a wake source, turn them off. */
if (device_may_wakeup(dev))
disable_irq_wake(info->tegra_rtc_irq);
return 0;
}
#endif
static SIMPLE_DEV_PM_OPS(tegra_rtc_pm_ops, tegra_rtc_suspend, tegra_rtc_resume);
static void tegra_rtc_shutdown(struct platform_device *pdev)
{
dev_vdbg(&pdev->dev, "disabling interrupts.\n");
tegra_rtc_alarm_irq_enable(&pdev->dev, 0);
}
MODULE_ALIAS("platform:tegra_rtc");
static struct platform_driver tegra_rtc_driver = {
.remove = tegra_rtc_remove,
.shutdown = tegra_rtc_shutdown,
.driver = {
.name = "tegra_rtc",
.of_match_table = tegra_rtc_dt_match,
.pm = &tegra_rtc_pm_ops,
},
};
module_platform_driver_probe(tegra_rtc_driver, tegra_rtc_probe);
MODULE_AUTHOR("Jon Mayo <jmayo@nvidia.com>");
MODULE_DESCRIPTION("driver for Tegra internal RTC");
MODULE_LICENSE("GPL");
