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linux/drivers/rtc/rtc-ab8500.c
Lee Jones ad49fcbe90 drivers/rtc/rtc-ab8500.c: ensure correct probing of the AB8500 RTC when Device Tree is enabled 
Without this patch, if Device Tree is enabled the AB8500 RTC wouldn't get
probed at all, as there is no reference to it from platform code.  This
patch ensures the driver is probed during normal DT start-up.

[akpm@linux-foundation.org: checkpatch fixes]
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-07-11 16:04:44 -07:00

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/*
* Copyright (C) ST-Ericsson SA 2010
*
* License terms: GNU General Public License (GPL) version 2
* Author: Virupax Sadashivpetimath <virupax.sadashivpetimath@stericsson.com>
*
* RTC clock driver for the RTC part of the AB8500 Power management chip.
* Based on RTC clock driver for the AB3100 Analog Baseband Chip by
* Linus Walleij <linus.walleij@stericsson.com>
*/
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/platform_device.h>
#include <linux/rtc.h>
#include <linux/mfd/abx500.h>
#include <linux/mfd/abx500/ab8500.h>
#include <linux/delay.h>
#include <linux/of.h>
#define AB8500_RTC_SOFF_STAT_REG 0x00
#define AB8500_RTC_CC_CONF_REG 0x01
#define AB8500_RTC_READ_REQ_REG 0x02
#define AB8500_RTC_WATCH_TSECMID_REG 0x03
#define AB8500_RTC_WATCH_TSECHI_REG 0x04
#define AB8500_RTC_WATCH_TMIN_LOW_REG 0x05
#define AB8500_RTC_WATCH_TMIN_MID_REG 0x06
#define AB8500_RTC_WATCH_TMIN_HI_REG 0x07
#define AB8500_RTC_ALRM_MIN_LOW_REG 0x08
#define AB8500_RTC_ALRM_MIN_MID_REG 0x09
#define AB8500_RTC_ALRM_MIN_HI_REG 0x0A
#define AB8500_RTC_STAT_REG 0x0B
#define AB8500_RTC_BKUP_CHG_REG 0x0C
#define AB8500_RTC_FORCE_BKUP_REG 0x0D
#define AB8500_RTC_CALIB_REG 0x0E
#define AB8500_RTC_SWITCH_STAT_REG 0x0F
/* RtcReadRequest bits */
#define RTC_READ_REQUEST 0x01
#define RTC_WRITE_REQUEST 0x02
/* RtcCtrl bits */
#define RTC_ALARM_ENA 0x04
#define RTC_STATUS_DATA 0x01
#define COUNTS_PER_SEC (0xF000 / 60)
#define AB8500_RTC_EPOCH 2000
static const u8 ab8500_rtc_time_regs[] = {
AB8500_RTC_WATCH_TMIN_HI_REG, AB8500_RTC_WATCH_TMIN_MID_REG,
AB8500_RTC_WATCH_TMIN_LOW_REG, AB8500_RTC_WATCH_TSECHI_REG,
AB8500_RTC_WATCH_TSECMID_REG
};
static const u8 ab8500_rtc_alarm_regs[] = {
AB8500_RTC_ALRM_MIN_HI_REG, AB8500_RTC_ALRM_MIN_MID_REG,
AB8500_RTC_ALRM_MIN_LOW_REG
};
/* Calculate the seconds from 1970 to 01-01-2000 00:00:00 */
static unsigned long get_elapsed_seconds(int year)
{
unsigned long secs;
struct rtc_time tm = {
.tm_year = year - 1900,
.tm_mday = 1,
};
/*
* This function calculates secs from 1970 and not from
* 1900, even if we supply the offset from year 1900.
*/
rtc_tm_to_time(&tm, &secs);
return secs;
}
static int ab8500_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
unsigned long timeout = jiffies + HZ;
int retval, i;
unsigned long mins, secs;
unsigned char buf[ARRAY_SIZE(ab8500_rtc_time_regs)];
u8 value;
/* Request a data read */
retval = abx500_set_register_interruptible(dev,
AB8500_RTC, AB8500_RTC_READ_REQ_REG, RTC_READ_REQUEST);
if (retval < 0)
return retval;
/* Early AB8500 chips will not clear the rtc read request bit */
if (abx500_get_chip_id(dev) == 0) {
usleep_range(1000, 1000);
} else {
/* Wait for some cycles after enabling the rtc read in ab8500 */
while (time_before(jiffies, timeout)) {
retval = abx500_get_register_interruptible(dev,
AB8500_RTC, AB8500_RTC_READ_REQ_REG, &value);
if (retval < 0)
return retval;
if (!(value & RTC_READ_REQUEST))
break;
usleep_range(1000, 5000);
}
}
/* Read the Watchtime registers */
for (i = 0; i < ARRAY_SIZE(ab8500_rtc_time_regs); i++) {
retval = abx500_get_register_interruptible(dev,
AB8500_RTC, ab8500_rtc_time_regs[i], &value);
if (retval < 0)
return retval;
buf[i] = value;
}
mins = (buf[0] << 16) | (buf[1] << 8) | buf[2];
secs = (buf[3] << 8) | buf[4];
secs = secs / COUNTS_PER_SEC;
secs = secs + (mins * 60);
/* Add back the initially subtracted number of seconds */
secs += get_elapsed_seconds(AB8500_RTC_EPOCH);
rtc_time_to_tm(secs, tm);
return rtc_valid_tm(tm);
}
static int ab8500_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
int retval, i;
unsigned char buf[ARRAY_SIZE(ab8500_rtc_time_regs)];
unsigned long no_secs, no_mins, secs = 0;
if (tm->tm_year < (AB8500_RTC_EPOCH - 1900)) {
dev_dbg(dev, "year should be equal to or greater than %d\n",
AB8500_RTC_EPOCH);
return -EINVAL;
}
/* Get the number of seconds since 1970 */
rtc_tm_to_time(tm, &secs);
/*
* Convert it to the number of seconds since 01-01-2000 00:00:00, since
* we only have a small counter in the RTC.
*/
secs -= get_elapsed_seconds(AB8500_RTC_EPOCH);
no_mins = secs / 60;
no_secs = secs % 60;
/* Make the seconds count as per the RTC resolution */
no_secs = no_secs * COUNTS_PER_SEC;
buf[4] = no_secs & 0xFF;
buf[3] = (no_secs >> 8) & 0xFF;
buf[2] = no_mins & 0xFF;
buf[1] = (no_mins >> 8) & 0xFF;
buf[0] = (no_mins >> 16) & 0xFF;
for (i = 0; i < ARRAY_SIZE(ab8500_rtc_time_regs); i++) {
retval = abx500_set_register_interruptible(dev, AB8500_RTC,
ab8500_rtc_time_regs[i], buf[i]);
if (retval < 0)
return retval;
}
/* Request a data write */
return abx500_set_register_interruptible(dev, AB8500_RTC,
AB8500_RTC_READ_REQ_REG, RTC_WRITE_REQUEST);
}
static int ab8500_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
{
int retval, i;
u8 rtc_ctrl, value;
unsigned char buf[ARRAY_SIZE(ab8500_rtc_alarm_regs)];
unsigned long secs, mins;
/* Check if the alarm is enabled or not */
retval = abx500_get_register_interruptible(dev, AB8500_RTC,
AB8500_RTC_STAT_REG, &rtc_ctrl);
if (retval < 0)
return retval;
if (rtc_ctrl & RTC_ALARM_ENA)
alarm->enabled = 1;
else
alarm->enabled = 0;
alarm->pending = 0;
for (i = 0; i < ARRAY_SIZE(ab8500_rtc_alarm_regs); i++) {
retval = abx500_get_register_interruptible(dev, AB8500_RTC,
ab8500_rtc_alarm_regs[i], &value);
if (retval < 0)
return retval;
buf[i] = value;
}
mins = (buf[0] << 16) | (buf[1] << 8) | (buf[2]);
secs = mins * 60;
/* Add back the initially subtracted number of seconds */
secs += get_elapsed_seconds(AB8500_RTC_EPOCH);
rtc_time_to_tm(secs, &alarm->time);
return rtc_valid_tm(&alarm->time);
}
static int ab8500_rtc_irq_enable(struct device *dev, unsigned int enabled)
{
return abx500_mask_and_set_register_interruptible(dev, AB8500_RTC,
AB8500_RTC_STAT_REG, RTC_ALARM_ENA,
enabled ? RTC_ALARM_ENA : 0);
}
static int ab8500_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
{
int retval, i;
unsigned char buf[ARRAY_SIZE(ab8500_rtc_alarm_regs)];
unsigned long mins, secs = 0;
if (alarm->time.tm_year < (AB8500_RTC_EPOCH - 1900)) {
dev_dbg(dev, "year should be equal to or greater than %d\n",
AB8500_RTC_EPOCH);
return -EINVAL;
}
/* Get the number of seconds since 1970 */
rtc_tm_to_time(&alarm->time, &secs);
/*
* Convert it to the number of seconds since 01-01-2000 00:00:00, since
* we only have a small counter in the RTC.
*/
secs -= get_elapsed_seconds(AB8500_RTC_EPOCH);
mins = secs / 60;
buf[2] = mins & 0xFF;
buf[1] = (mins >> 8) & 0xFF;
buf[0] = (mins >> 16) & 0xFF;
/* Set the alarm time */
for (i = 0; i < ARRAY_SIZE(ab8500_rtc_alarm_regs); i++) {
retval = abx500_set_register_interruptible(dev, AB8500_RTC,
ab8500_rtc_alarm_regs[i], buf[i]);
if (retval < 0)
return retval;
}
return ab8500_rtc_irq_enable(dev, alarm->enabled);
}
static int ab8500_rtc_set_calibration(struct device *dev, int calibration)
{
int retval;
u8 rtccal = 0;
/*
* Check that the calibration value (which is in units of 0.5
* parts-per-million) is in the AB8500's range for RtcCalibration
* register. -128 (0x80) is not permitted because the AB8500 uses
* a sign-bit rather than two's complement, so 0x80 is just another
* representation of zero.
*/
if ((calibration < -127) || (calibration > 127)) {
dev_err(dev, "RtcCalibration value outside permitted range\n");
return -EINVAL;
}
/*
* The AB8500 uses sign (in bit7) and magnitude (in bits0-7)
* so need to convert to this sort of representation before writing
* into RtcCalibration register...
*/
if (calibration >= 0)
rtccal = 0x7F & calibration;
else
rtccal = ~(calibration - 1) | 0x80;
retval = abx500_set_register_interruptible(dev, AB8500_RTC,
AB8500_RTC_CALIB_REG, rtccal);
return retval;
}
static int ab8500_rtc_get_calibration(struct device *dev, int *calibration)
{
int retval;
u8 rtccal = 0;
retval = abx500_get_register_interruptible(dev, AB8500_RTC,
AB8500_RTC_CALIB_REG, &rtccal);
if (retval >= 0) {
/*
* The AB8500 uses sign (in bit7) and magnitude (in bits0-7)
* so need to convert value from RtcCalibration register into
* a two's complement signed value...
*/
if (rtccal & 0x80)
*calibration = 0 - (rtccal & 0x7F);
else
*calibration = 0x7F & rtccal;
}
return retval;
}
static ssize_t ab8500_sysfs_store_rtc_calibration(struct device *dev,
struct device_attribute *attr,
const char *buf, size_t count)
{
int retval;
int calibration = 0;
if (sscanf(buf, " %i ", &calibration) != 1) {
dev_err(dev, "Failed to store RTC calibration attribute\n");
return -EINVAL;
}
retval = ab8500_rtc_set_calibration(dev, calibration);
return retval ? retval : count;
}
static ssize_t ab8500_sysfs_show_rtc_calibration(struct device *dev,
struct device_attribute *attr, char *buf)
{
int retval = 0;
int calibration = 0;
retval = ab8500_rtc_get_calibration(dev, &calibration);
if (retval < 0) {
dev_err(dev, "Failed to read RTC calibration attribute\n");
sprintf(buf, "0\n");
return retval;
}
return sprintf(buf, "%d\n", calibration);
}
static DEVICE_ATTR(rtc_calibration, S_IRUGO | S_IWUSR,
ab8500_sysfs_show_rtc_calibration,
ab8500_sysfs_store_rtc_calibration);
static int ab8500_sysfs_rtc_register(struct device *dev)
{
return device_create_file(dev, &dev_attr_rtc_calibration);
}
static void ab8500_sysfs_rtc_unregister(struct device *dev)
{
device_remove_file(dev, &dev_attr_rtc_calibration);
}
static irqreturn_t rtc_alarm_handler(int irq, void *data)
{
struct rtc_device *rtc = data;
unsigned long events = RTC_IRQF | RTC_AF;
dev_dbg(&rtc->dev, "%s\n", __func__);
rtc_update_irq(rtc, 1, events);
return IRQ_HANDLED;
}
static const struct rtc_class_ops ab8500_rtc_ops = {
.read_time = ab8500_rtc_read_time,
.set_time = ab8500_rtc_set_time,
.read_alarm = ab8500_rtc_read_alarm,
.set_alarm = ab8500_rtc_set_alarm,
.alarm_irq_enable = ab8500_rtc_irq_enable,
};
static int __devinit ab8500_rtc_probe(struct platform_device *pdev)
{
int err;
struct rtc_device *rtc;
u8 rtc_ctrl;
int irq;
irq = platform_get_irq_byname(pdev, "ALARM");
if (irq < 0)
return irq;
/* For RTC supply test */
err = abx500_mask_and_set_register_interruptible(&pdev->dev, AB8500_RTC,
AB8500_RTC_STAT_REG, RTC_STATUS_DATA, RTC_STATUS_DATA);
if (err < 0)
return err;
/* Wait for reset by the PorRtc */
usleep_range(1000, 5000);
err = abx500_get_register_interruptible(&pdev->dev, AB8500_RTC,
AB8500_RTC_STAT_REG, &rtc_ctrl);
if (err < 0)
return err;
/* Check if the RTC Supply fails */
if (!(rtc_ctrl & RTC_STATUS_DATA)) {
dev_err(&pdev->dev, "RTC supply failure\n");
return -ENODEV;
}
device_init_wakeup(&pdev->dev, true);
rtc = rtc_device_register("ab8500-rtc", &pdev->dev, &ab8500_rtc_ops,
THIS_MODULE);
if (IS_ERR(rtc)) {
dev_err(&pdev->dev, "Registration failed\n");
err = PTR_ERR(rtc);
return err;
}
err = request_threaded_irq(irq, NULL, rtc_alarm_handler,
IRQF_NO_SUSPEND | IRQF_ONESHOT, "ab8500-rtc", rtc);
if (err < 0) {
rtc_device_unregister(rtc);
return err;
}
platform_set_drvdata(pdev, rtc);
err = ab8500_sysfs_rtc_register(&pdev->dev);
if (err) {
dev_err(&pdev->dev, "sysfs RTC failed to register\n");
return err;
}
return 0;
}
static int __devexit ab8500_rtc_remove(struct platform_device *pdev)
{
struct rtc_device *rtc = platform_get_drvdata(pdev);
int irq = platform_get_irq_byname(pdev, "ALARM");
ab8500_sysfs_rtc_unregister(&pdev->dev);
free_irq(irq, rtc);
rtc_device_unregister(rtc);
platform_set_drvdata(pdev, NULL);
return 0;
}
static const struct of_device_id ab8500_rtc_match[] = {
{ .compatible = "stericsson,ab8500-rtc", },
{}
};
static struct platform_driver ab8500_rtc_driver = {
.driver = {
.name = "ab8500-rtc",
.owner = THIS_MODULE,
.of_match_table = ab8500_rtc_match,
},
.probe = ab8500_rtc_probe,
.remove = __devexit_p(ab8500_rtc_remove),
};
module_platform_driver(ab8500_rtc_driver);
MODULE_AUTHOR("Virupax Sadashivpetimath <virupax.sadashivpetimath@stericsson.com>");
MODULE_DESCRIPTION("AB8500 RTC Driver");
MODULE_LICENSE("GPL v2");
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