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linux/drivers/rtc/rtc-ab3100.c
Linus Walleij bd207cfb00 rtc: AB3100 RTC support 
This adds support for the RTC found inside the AB3100 Mixed Signal chip.
The symbols used for communicating with the chip is found in the
mfd/ab3100-core.c driver that also provides the platform device.

Signed-off-by: Linus Walleij <linus.walleij@stericsson.com>
Acked-by: Alessandro Zummo <alessandro.zummo@towertech.it>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
2009-09-17 09:47:24 +02:00

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/*
* Copyright (C) 2007-2009 ST-Ericsson AB
* License terms: GNU General Public License (GPL) version 2
* RTC clock driver for the AB3100 Analog Baseband Chip
* Author: 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/ab3100.h>
/* Clock rate in Hz */
#define AB3100_RTC_CLOCK_RATE 32768
/*
* The AB3100 RTC registers. These are the same for
* AB3000 and AB3100.
* Control register:
* Bit 0: RTC Monitor cleared=0, active=1, if you set it
* to 1 it remains active until RTC power is lost.
* Bit 1: 32 kHz Oscillator, 0 = on, 1 = bypass
* Bit 2: Alarm on, 0 = off, 1 = on
* Bit 3: 32 kHz buffer disabling, 0 = enabled, 1 = disabled
*/
#define AB3100_RTC 0x53
/* default setting, buffer disabled, alarm on */
#define RTC_SETTING 0x30
/* Alarm when AL0-AL3 == TI0-TI3 */
#define AB3100_AL0 0x56
#define AB3100_AL1 0x57
#define AB3100_AL2 0x58
#define AB3100_AL3 0x59
/* This 48-bit register that counts up at 32768 Hz */
#define AB3100_TI0 0x5a
#define AB3100_TI1 0x5b
#define AB3100_TI2 0x5c
#define AB3100_TI3 0x5d
#define AB3100_TI4 0x5e
#define AB3100_TI5 0x5f
/*
* RTC clock functions and device struct declaration
*/
static int ab3100_rtc_set_mmss(struct device *dev, unsigned long secs)
{
struct ab3100 *ab3100_data = dev_get_drvdata(dev);
u8 regs[] = {AB3100_TI0, AB3100_TI1, AB3100_TI2,
AB3100_TI3, AB3100_TI4, AB3100_TI5};
unsigned char buf[6];
u64 fat_time = (u64) secs * AB3100_RTC_CLOCK_RATE * 2;
int err = 0;
int i;
buf[0] = (fat_time) & 0xFF;
buf[1] = (fat_time >> 8) & 0xFF;
buf[2] = (fat_time >> 16) & 0xFF;
buf[3] = (fat_time >> 24) & 0xFF;
buf[4] = (fat_time >> 32) & 0xFF;
buf[5] = (fat_time >> 40) & 0xFF;
for (i = 0; i < 6; i++) {
err = ab3100_set_register_interruptible(ab3100_data,
regs[i], buf[i]);
if (err)
return err;
}
/* Set the flag to mark that the clock is now set */
return ab3100_mask_and_set_register_interruptible(ab3100_data,
AB3100_RTC,
0xFE, 0x01);
}
static int ab3100_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
struct ab3100 *ab3100_data = dev_get_drvdata(dev);
unsigned long time;
u8 rtcval;
int err;
err = ab3100_get_register_interruptible(ab3100_data,
AB3100_RTC, &rtcval);
if (err)
return err;
if (!(rtcval & 0x01)) {
dev_info(dev, "clock not set (lost power)");
return -EINVAL;
} else {
u64 fat_time;
u8 buf[6];
/* Read out time registers */
err = ab3100_get_register_page_interruptible(ab3100_data,
AB3100_TI0,
buf, 6);
if (err != 0)
return err;
fat_time = ((u64) buf[5] << 40) | ((u64) buf[4] << 32) |
((u64) buf[3] << 24) | ((u64) buf[2] << 16) |
((u64) buf[1] << 8) | (u64) buf[0];
time = (unsigned long) (fat_time /
(u64) (AB3100_RTC_CLOCK_RATE * 2));
}
rtc_time_to_tm(time, tm);
return rtc_valid_tm(tm);
}
static int ab3100_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
{
struct ab3100 *ab3100_data = dev_get_drvdata(dev);
unsigned long time;
u64 fat_time;
u8 buf[6];
u8 rtcval;
int err;
/* Figure out if alarm is enabled or not */
err = ab3100_get_register_interruptible(ab3100_data,
AB3100_RTC, &rtcval);
if (err)
return err;
if (rtcval & 0x04)
alarm->enabled = 1;
else
alarm->enabled = 0;
/* No idea how this could be represented */
alarm->pending = 0;
/* Read out alarm registers, only 4 bytes */
err = ab3100_get_register_page_interruptible(ab3100_data,
AB3100_AL0, buf, 4);
if (err)
return err;
fat_time = ((u64) buf[3] << 40) | ((u64) buf[2] << 32) |
((u64) buf[1] << 24) | ((u64) buf[0] << 16);
time = (unsigned long) (fat_time / (u64) (AB3100_RTC_CLOCK_RATE * 2));
rtc_time_to_tm(time, &alarm->time);
return rtc_valid_tm(&alarm->time);
}
static int ab3100_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
{
struct ab3100 *ab3100_data = dev_get_drvdata(dev);
u8 regs[] = {AB3100_AL0, AB3100_AL1, AB3100_AL2, AB3100_AL3};
unsigned char buf[4];
unsigned long secs;
u64 fat_time;
int err;
int i;
rtc_tm_to_time(&alarm->time, &secs);
fat_time = (u64) secs * AB3100_RTC_CLOCK_RATE * 2;
buf[0] = (fat_time >> 16) & 0xFF;
buf[1] = (fat_time >> 24) & 0xFF;
buf[2] = (fat_time >> 32) & 0xFF;
buf[3] = (fat_time >> 40) & 0xFF;
/* Set the alarm */
for (i = 0; i < 4; i++) {
err = ab3100_set_register_interruptible(ab3100_data,
regs[i], buf[i]);
if (err)
return err;
}
/* Then enable the alarm */
return ab3100_mask_and_set_register_interruptible(ab3100_data,
AB3100_RTC, ~(1 << 2),
alarm->enabled << 2);
}
static int ab3100_rtc_irq_enable(struct device *dev, unsigned int enabled)
{
struct ab3100 *ab3100_data = dev_get_drvdata(dev);
/*
* It's not possible to enable/disable the alarm IRQ for this RTC.
* It does not actually trigger any IRQ: instead its only function is
* to power up the system, if it wasn't on. This will manifest as
* a "power up cause" in the AB3100 power driver (battery charging etc)
* and need to be handled there instead.
*/
if (enabled)
return ab3100_mask_and_set_register_interruptible(ab3100_data,
AB3100_RTC, ~(1 << 2),
1 << 2);
else
return ab3100_mask_and_set_register_interruptible(ab3100_data,
AB3100_RTC, ~(1 << 2),
0);
}
static const struct rtc_class_ops ab3100_rtc_ops = {
.read_time = ab3100_rtc_read_time,
.set_mmss = ab3100_rtc_set_mmss,
.read_alarm = ab3100_rtc_read_alarm,
.set_alarm = ab3100_rtc_set_alarm,
.alarm_irq_enable = ab3100_rtc_irq_enable,
};
static int __init ab3100_rtc_probe(struct platform_device *pdev)
{
int err;
u8 regval;
struct rtc_device *rtc;
struct ab3100 *ab3100_data = platform_get_drvdata(pdev);
/* The first RTC register needs special treatment */
err = ab3100_get_register_interruptible(ab3100_data,
AB3100_RTC, &regval);
if (err) {
dev_err(&pdev->dev, "unable to read RTC register\n");
return -ENODEV;
}
if ((regval & 0xFE) != RTC_SETTING) {
dev_warn(&pdev->dev, "not default value in RTC reg 0x%x\n",
regval);
}
if ((regval & 1) == 0) {
/*
* Set bit to detect power loss.
* This bit remains until RTC power is lost.
*/
regval = 1 | RTC_SETTING;
err = ab3100_set_register_interruptible(ab3100_data,
AB3100_RTC, regval);
/* Ignore any error on this write */
}
rtc = rtc_device_register("ab3100-rtc", &pdev->dev, &ab3100_rtc_ops,
THIS_MODULE);
if (IS_ERR(rtc)) {
err = PTR_ERR(rtc);
return err;
}
return 0;
}
static int __exit ab3100_rtc_remove(struct platform_device *pdev)
{
struct rtc_device *rtc = platform_get_drvdata(pdev);
rtc_device_unregister(rtc);
return 0;
}
static struct platform_driver ab3100_rtc_driver = {
.driver = {
.name = "ab3100-rtc",
.owner = THIS_MODULE,
},
.remove = __exit_p(ab3100_rtc_remove),
};
static int __init ab3100_rtc_init(void)
{
return platform_driver_probe(&ab3100_rtc_driver,
ab3100_rtc_probe);
}
static void __exit ab3100_rtc_exit(void)
{
platform_driver_unregister(&ab3100_rtc_driver);
}
module_init(ab3100_rtc_init);
module_exit(ab3100_rtc_exit);
MODULE_AUTHOR("Linus Walleij <linus.walleij@stericsson.com>");
MODULE_DESCRIPTION("AB3100 RTC Driver");
MODULE_LICENSE("GPL");
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