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linux/drivers/rtc/rtc-rk808.c
Chris Zhong c412c6034a drivers/rtc/rtc-rk808.c: fix rtc time reading issue 
After we set the GET_TIME bit, the rtc time can't be read immediately.  We
should wait up to 31.25 us, about one cycle of 32khz.  Otherwise reading
RTC time will return a old time.  If we clear the GET_TIME bit after
setting, the time of i2c transfer is certainly more than 31.25us.

Doug said:

: I think we are safe.  At 400kHz (the max speed of this part) each bit can
: be transferred no faster than 2.5us.  In order to do a valid i2c
: transaction we need to _at least_ write the address of the device and the
: data onto the bus, which is 16 bits.  16 * 2.5us = 40us.  That's above the
: 31.25us

[akpm@linux-foundation.org: tweak comment per review discussion]
Signed-off-by: Chris Zhong <zyw@rock-chips.com>
Reviewed-by: Doug Anderson <dianders@chromium.org>
Cc: Sonny Rao <sonnyrao@chromium.org>
Cc: Heiko Stübner <heiko@sntech.de>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-13 21:21:43 -08:00

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/*
* RTC driver for Rockchip RK808
*
* Copyright (c) 2014, Fuzhou Rockchip Electronics Co., Ltd
*
* Author: Chris Zhong <zyw@rock-chips.com>
* Author: Zhang Qing <zhangqing@rock-chips.com>
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
* version 2, as published by the Free Software Foundation.
*
* This program is distributed in the hope 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/module.h>
#include <linux/kernel.h>
#include <linux/rtc.h>
#include <linux/bcd.h>
#include <linux/mfd/rk808.h>
#include <linux/platform_device.h>
#include <linux/i2c.h>
/* RTC_CTRL_REG bitfields */
#define BIT_RTC_CTRL_REG_STOP_RTC_M BIT(0)
/* RK808 has a shadowed register for saving a "frozen" RTC time.
* When user setting "GET_TIME" to 1, the time will save in this shadowed
* register. If set "READSEL" to 1, user read rtc time register, actually
* get the time of that moment. If we need the real time, clr this bit.
*/
#define BIT_RTC_CTRL_REG_RTC_GET_TIME BIT(6)
#define BIT_RTC_CTRL_REG_RTC_READSEL_M BIT(7)
#define BIT_RTC_INTERRUPTS_REG_IT_ALARM_M BIT(3)
#define RTC_STATUS_MASK 0xFE
#define SECONDS_REG_MSK 0x7F
#define MINUTES_REG_MAK 0x7F
#define HOURS_REG_MSK 0x3F
#define DAYS_REG_MSK 0x3F
#define MONTHS_REG_MSK 0x1F
#define YEARS_REG_MSK 0xFF
#define WEEKS_REG_MSK 0x7
/* REG_SECONDS_REG through REG_YEARS_REG is how many registers? */
#define NUM_TIME_REGS (RK808_WEEKS_REG - RK808_SECONDS_REG + 1)
#define NUM_ALARM_REGS (RK808_ALARM_YEARS_REG - RK808_ALARM_SECONDS_REG + 1)
struct rk808_rtc {
struct rk808 *rk808;
struct rtc_device *rtc;
int irq;
};
/* Read current time and date in RTC */
static int rk808_rtc_readtime(struct device *dev, struct rtc_time *tm)
{
struct rk808_rtc *rk808_rtc = dev_get_drvdata(dev);
struct rk808 *rk808 = rk808_rtc->rk808;
u8 rtc_data[NUM_TIME_REGS];
int ret;
/* Force an update of the shadowed registers right now */
ret = regmap_update_bits(rk808->regmap, RK808_RTC_CTRL_REG,
BIT_RTC_CTRL_REG_RTC_GET_TIME,
BIT_RTC_CTRL_REG_RTC_GET_TIME);
if (ret) {
dev_err(dev, "Failed to update bits rtc_ctrl: %d\n", ret);
return ret;
}
/*
* After we set the GET_TIME bit, the rtc time can't be read
* immediately. So we should wait up to 31.25 us, about one cycle of
* 32khz. If we clear the GET_TIME bit here, the time of i2c transfer
* certainly more than 31.25us: 16 * 2.5us at 400kHz bus frequency.
*/
ret = regmap_update_bits(rk808->regmap, RK808_RTC_CTRL_REG,
BIT_RTC_CTRL_REG_RTC_GET_TIME,
0);
if (ret) {
dev_err(dev, "Failed to update bits rtc_ctrl: %d\n", ret);
return ret;
}
ret = regmap_bulk_read(rk808->regmap, RK808_SECONDS_REG,
rtc_data, NUM_TIME_REGS);
if (ret) {
dev_err(dev, "Failed to bulk read rtc_data: %d\n", ret);
return ret;
}
tm->tm_sec = bcd2bin(rtc_data[0] & SECONDS_REG_MSK);
tm->tm_min = bcd2bin(rtc_data[1] & MINUTES_REG_MAK);
tm->tm_hour = bcd2bin(rtc_data[2] & HOURS_REG_MSK);
tm->tm_mday = bcd2bin(rtc_data[3] & DAYS_REG_MSK);
tm->tm_mon = (bcd2bin(rtc_data[4] & MONTHS_REG_MSK)) - 1;
tm->tm_year = (bcd2bin(rtc_data[5] & YEARS_REG_MSK)) + 100;
tm->tm_wday = bcd2bin(rtc_data[6] & WEEKS_REG_MSK);
dev_dbg(dev, "RTC date/time %4d-%02d-%02d(%d) %02d:%02d:%02d\n",
1900 + tm->tm_year, tm->tm_mon + 1, tm->tm_mday,
tm->tm_wday, tm->tm_hour , tm->tm_min, tm->tm_sec);
return ret;
}
/* Set current time and date in RTC */
static int rk808_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
struct rk808_rtc *rk808_rtc = dev_get_drvdata(dev);
struct rk808 *rk808 = rk808_rtc->rk808;
u8 rtc_data[NUM_TIME_REGS];
int ret;
rtc_data[0] = bin2bcd(tm->tm_sec);
rtc_data[1] = bin2bcd(tm->tm_min);
rtc_data[2] = bin2bcd(tm->tm_hour);
rtc_data[3] = bin2bcd(tm->tm_mday);
rtc_data[4] = bin2bcd(tm->tm_mon + 1);
rtc_data[5] = bin2bcd(tm->tm_year - 100);
rtc_data[6] = bin2bcd(tm->tm_wday);
dev_dbg(dev, "set RTC date/time %4d-%02d-%02d(%d) %02d:%02d:%02d\n",
1900 + tm->tm_year, tm->tm_mon + 1, tm->tm_mday,
tm->tm_wday, tm->tm_hour , tm->tm_min, tm->tm_sec);
/* Stop RTC while updating the RTC registers */
ret = regmap_update_bits(rk808->regmap, RK808_RTC_CTRL_REG,
BIT_RTC_CTRL_REG_STOP_RTC_M,
BIT_RTC_CTRL_REG_STOP_RTC_M);
if (ret) {
dev_err(dev, "Failed to update RTC control: %d\n", ret);
return ret;
}
ret = regmap_bulk_write(rk808->regmap, RK808_SECONDS_REG,
rtc_data, NUM_TIME_REGS);
if (ret) {
dev_err(dev, "Failed to bull write rtc_data: %d\n", ret);
return ret;
}
/* Start RTC again */
ret = regmap_update_bits(rk808->regmap, RK808_RTC_CTRL_REG,
BIT_RTC_CTRL_REG_STOP_RTC_M, 0);
if (ret) {
dev_err(dev, "Failed to update RTC control: %d\n", ret);
return ret;
}
return 0;
}
/* Read alarm time and date in RTC */
static int rk808_rtc_readalarm(struct device *dev, struct rtc_wkalrm *alrm)
{
struct rk808_rtc *rk808_rtc = dev_get_drvdata(dev);
struct rk808 *rk808 = rk808_rtc->rk808;
u8 alrm_data[NUM_ALARM_REGS];
uint32_t int_reg;
int ret;
ret = regmap_bulk_read(rk808->regmap, RK808_ALARM_SECONDS_REG,
alrm_data, NUM_ALARM_REGS);
alrm->time.tm_sec = bcd2bin(alrm_data[0] & SECONDS_REG_MSK);
alrm->time.tm_min = bcd2bin(alrm_data[1] & MINUTES_REG_MAK);
alrm->time.tm_hour = bcd2bin(alrm_data[2] & HOURS_REG_MSK);
alrm->time.tm_mday = bcd2bin(alrm_data[3] & DAYS_REG_MSK);
alrm->time.tm_mon = (bcd2bin(alrm_data[4] & MONTHS_REG_MSK)) - 1;
alrm->time.tm_year = (bcd2bin(alrm_data[5] & YEARS_REG_MSK)) + 100;
ret = regmap_read(rk808->regmap, RK808_RTC_INT_REG, &int_reg);
if (ret) {
dev_err(dev, "Failed to read RTC INT REG: %d\n", ret);
return ret;
}
dev_dbg(dev, "alrm read RTC date/time %4d-%02d-%02d(%d) %02d:%02d:%02d\n",
1900 + alrm->time.tm_year, alrm->time.tm_mon + 1,
alrm->time.tm_mday, alrm->time.tm_wday, alrm->time.tm_hour,
alrm->time.tm_min, alrm->time.tm_sec);
alrm->enabled = (int_reg & BIT_RTC_INTERRUPTS_REG_IT_ALARM_M) ? 1 : 0;
return 0;
}
static int rk808_rtc_stop_alarm(struct rk808_rtc *rk808_rtc)
{
struct rk808 *rk808 = rk808_rtc->rk808;
int ret;
ret = regmap_update_bits(rk808->regmap, RK808_RTC_INT_REG,
BIT_RTC_INTERRUPTS_REG_IT_ALARM_M, 0);
return ret;
}
static int rk808_rtc_start_alarm(struct rk808_rtc *rk808_rtc)
{
struct rk808 *rk808 = rk808_rtc->rk808;
int ret;
ret = regmap_update_bits(rk808->regmap, RK808_RTC_INT_REG,
BIT_RTC_INTERRUPTS_REG_IT_ALARM_M,
BIT_RTC_INTERRUPTS_REG_IT_ALARM_M);
return ret;
}
static int rk808_rtc_setalarm(struct device *dev, struct rtc_wkalrm *alrm)
{
struct rk808_rtc *rk808_rtc = dev_get_drvdata(dev);
struct rk808 *rk808 = rk808_rtc->rk808;
u8 alrm_data[NUM_ALARM_REGS];
int ret;
ret = rk808_rtc_stop_alarm(rk808_rtc);
if (ret) {
dev_err(dev, "Failed to stop alarm: %d\n", ret);
return ret;
}
dev_dbg(dev, "alrm set RTC date/time %4d-%02d-%02d(%d) %02d:%02d:%02d\n",
1900 + alrm->time.tm_year, alrm->time.tm_mon + 1,
alrm->time.tm_mday, alrm->time.tm_wday, alrm->time.tm_hour,
alrm->time.tm_min, alrm->time.tm_sec);
alrm_data[0] = bin2bcd(alrm->time.tm_sec);
alrm_data[1] = bin2bcd(alrm->time.tm_min);
alrm_data[2] = bin2bcd(alrm->time.tm_hour);
alrm_data[3] = bin2bcd(alrm->time.tm_mday);
alrm_data[4] = bin2bcd(alrm->time.tm_mon + 1);
alrm_data[5] = bin2bcd(alrm->time.tm_year - 100);
ret = regmap_bulk_write(rk808->regmap, RK808_ALARM_SECONDS_REG,
alrm_data, NUM_ALARM_REGS);
if (ret) {
dev_err(dev, "Failed to bulk write: %d\n", ret);
return ret;
}
if (alrm->enabled) {
ret = rk808_rtc_start_alarm(rk808_rtc);
if (ret) {
dev_err(dev, "Failed to start alarm: %d\n", ret);
return ret;
}
}
return 0;
}
static int rk808_rtc_alarm_irq_enable(struct device *dev,
unsigned int enabled)
{
struct rk808_rtc *rk808_rtc = dev_get_drvdata(dev);
if (enabled)
return rk808_rtc_start_alarm(rk808_rtc);
return rk808_rtc_stop_alarm(rk808_rtc);
}
/*
* We will just handle setting the frequency and make use the framework for
* reading the periodic interupts.
*
* @freq: Current periodic IRQ freq:
* bit 0: every second
* bit 1: every minute
* bit 2: every hour
* bit 3: every day
*/
static irqreturn_t rk808_alarm_irq(int irq, void *data)
{
struct rk808_rtc *rk808_rtc = data;
struct rk808 *rk808 = rk808_rtc->rk808;
struct i2c_client *client = rk808->i2c;
int ret;
ret = regmap_write(rk808->regmap, RK808_RTC_STATUS_REG,
RTC_STATUS_MASK);
if (ret) {
dev_err(&client->dev,
"%s:Failed to update RTC status: %d\n", __func__, ret);
return ret;
}
rtc_update_irq(rk808_rtc->rtc, 1, RTC_IRQF | RTC_AF);
dev_dbg(&client->dev,
"%s:irq=%d\n", __func__, irq);
return IRQ_HANDLED;
}
static const struct rtc_class_ops rk808_rtc_ops = {
.read_time = rk808_rtc_readtime,
.set_time = rk808_rtc_set_time,
.read_alarm = rk808_rtc_readalarm,
.set_alarm = rk808_rtc_setalarm,
.alarm_irq_enable = rk808_rtc_alarm_irq_enable,
};
#ifdef CONFIG_PM_SLEEP
/* Turn off the alarm if it should not be a wake source. */
static int rk808_rtc_suspend(struct device *dev)
{
struct platform_device *pdev = to_platform_device(dev);
struct rk808_rtc *rk808_rtc = dev_get_drvdata(&pdev->dev);
if (device_may_wakeup(dev))
enable_irq_wake(rk808_rtc->irq);
return 0;
}
/* Enable the alarm if it should be enabled (in case it was disabled to
* prevent use as a wake source).
*/
static int rk808_rtc_resume(struct device *dev)
{
struct platform_device *pdev = to_platform_device(dev);
struct rk808_rtc *rk808_rtc = dev_get_drvdata(&pdev->dev);
if (device_may_wakeup(dev))
disable_irq_wake(rk808_rtc->irq);
return 0;
}
#endif
static SIMPLE_DEV_PM_OPS(rk808_rtc_pm_ops,
rk808_rtc_suspend, rk808_rtc_resume);
static int rk808_rtc_probe(struct platform_device *pdev)
{
struct rk808 *rk808 = dev_get_drvdata(pdev->dev.parent);
struct rk808_rtc *rk808_rtc;
struct rtc_time tm;
int ret;
rk808_rtc = devm_kzalloc(&pdev->dev, sizeof(*rk808_rtc), GFP_KERNEL);
if (rk808_rtc == NULL)
return -ENOMEM;
platform_set_drvdata(pdev, rk808_rtc);
rk808_rtc->rk808 = rk808;
/* start rtc running by default, and use shadowed timer. */
ret = regmap_update_bits(rk808->regmap, RK808_RTC_CTRL_REG,
BIT_RTC_CTRL_REG_STOP_RTC_M |
BIT_RTC_CTRL_REG_RTC_READSEL_M,
BIT_RTC_CTRL_REG_RTC_READSEL_M);
if (ret) {
dev_err(&pdev->dev,
"Failed to update RTC control: %d\n", ret);
return ret;
}
ret = regmap_write(rk808->regmap, RK808_RTC_STATUS_REG,
RTC_STATUS_MASK);
if (ret) {
dev_err(&pdev->dev,
"Failed to write RTC status: %d\n", ret);
return ret;
}
/* set init time */
ret = rk808_rtc_readtime(&pdev->dev, &tm);
if (ret) {
dev_err(&pdev->dev, "Failed to read RTC time\n");
return ret;
}
ret = rtc_valid_tm(&tm);
if (ret)
dev_warn(&pdev->dev, "invalid date/time\n");
device_init_wakeup(&pdev->dev, 1);
rk808_rtc->rtc = devm_rtc_device_register(&pdev->dev, "rk808-rtc",
&rk808_rtc_ops, THIS_MODULE);
if (IS_ERR(rk808_rtc->rtc)) {
ret = PTR_ERR(rk808_rtc->rtc);
return ret;
}
rk808_rtc->irq = platform_get_irq(pdev, 0);
if (rk808_rtc->irq < 0) {
if (rk808_rtc->irq != -EPROBE_DEFER)
dev_err(&pdev->dev, "Wake up is not possible as irq = %d\n",
rk808_rtc->irq);
return rk808_rtc->irq;
}
/* request alarm irq of rk808 */
ret = devm_request_threaded_irq(&pdev->dev, rk808_rtc->irq, NULL,
rk808_alarm_irq, 0,
"RTC alarm", rk808_rtc);
if (ret) {
dev_err(&pdev->dev, "Failed to request alarm IRQ %d: %d\n",
rk808_rtc->irq, ret);
}
return ret;
}
static struct platform_driver rk808_rtc_driver = {
.probe = rk808_rtc_probe,
.driver = {
.name = "rk808-rtc",
.pm = &rk808_rtc_pm_ops,
},
};
module_platform_driver(rk808_rtc_driver);
MODULE_DESCRIPTION("RTC driver for the rk808 series PMICs");
MODULE_AUTHOR("Chris Zhong <zyw@rock-chips.com>");
MODULE_AUTHOR("Zhang Qing <zhangqing@rock-chips.com>");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:rk808-rtc");
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