AB3100 RTC support v1

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>
---
 drivers/rtc/Kconfig      |    9 ++
 drivers/rtc/Makefile     |    1 +
 drivers/rtc/rtc-ab3100.c |  281 ++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 291 insertions(+), 0 deletions(-)
 create mode 100644 drivers/rtc/rtc-ab3100.c

2009/7/12 Linus Walleij <linus.walleij@stericsson.com>:

> 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>

Any comments on this one? Acked-by from Alessandro atleast ?

Yours,
Linus Walleij

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On Sun, 12 Jul 2009 00:10:13 +0200
Linus Walleij <linus.walleij@stericsson.com> wrote:

> 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>

 Hi, a quick review below:

> ---
>  drivers/rtc/Kconfig      |    9 ++
>  drivers/rtc/Makefile     |    1 +
>  drivers/rtc/rtc-ab3100.c |  281 ++++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 291 insertions(+), 0 deletions(-)
>  create mode 100644 drivers/rtc/rtc-ab3100.c
> 
> diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
> index 81adbdb..a36dffd 100644
> --- a/drivers/rtc/Kconfig
> +++ b/drivers/rtc/Kconfig
> @@ -535,6 +535,15 @@ config RTC_DRV_PCF50633
>  	  If you say yes here you get support for the RTC subsystem of the
>  	  NXP PCF50633 used in embedded systems.
>  
> +config RTC_DRV_AB3100
> +	tristate "ST-Ericsson AB3100 RTC"
> +	depends on AB3100_CORE
> +	default y if AB3100_CORE
> +	help
> +	  Select this to enable the ST-Ericsson AB3100 Mixed Signal IC RTC
> +	  support. This chip contains a battery- and capacitor-backed RTC.
> +
> +
>  comment "on-CPU RTC drivers"
>  
>  config RTC_DRV_OMAP
> diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
> index 3c0f2b2..fe85afb 100644
> --- a/drivers/rtc/Makefile
> +++ b/drivers/rtc/Makefile
> @@ -17,6 +17,7 @@ rtc-core-$(CONFIG_RTC_INTF_SYSFS) += rtc-sysfs.o
>  
>  # Keep the list ordered.
>  
> +obj-$(CONFIG_RTC_DRV_AB3100)	+= rtc-ab3100.o
>  obj-$(CONFIG_RTC_DRV_AT32AP700X)+= rtc-at32ap700x.o
>  obj-$(CONFIG_RTC_DRV_AT91RM9200)+= rtc-at91rm9200.o
>  obj-$(CONFIG_RTC_DRV_AT91SAM9)	+= rtc-at91sam9.o
> diff --git a/drivers/rtc/rtc-ab3100.c b/drivers/rtc/rtc-ab3100.c
> new file mode 100644
> index 0000000..d178cf7
> --- /dev/null
> +++ b/drivers/rtc/rtc-ab3100.c
> @@ -0,0 +1,281 @@
> +/*
> + * 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(ab3100_data, regs[i], buf[i]);
> +		if (err)
> +			return err;
> +	}
> +
> +	/* Set the flag to mark that the clock is now set */
> +	err = ab3100_mask_and_set_register(ab3100_data, AB3100_RTC, 0xFE, 0x01);
> +
> +	return err;


 no need to assign err =

> +}
> +
> +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(ab3100_data, AB3100_RTC, &rtcval);

 err should be tested. given that rtcval is not initialized,
 it could contain any value.

> +
> +	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(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(ab3100_data, AB3100_RTC, &rtcval);
> +	if (err)
> +		return err;
> +	if (rtcval & 0x02)
> +		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(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 0;

 use rtc_valid_tm

> +}
> +
> +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(ab3100_data, regs[i], buf[i]);
> +		if (err)
> +			return err;
> +	}
> +	/* Then enable the alarm */
> +	err = ab3100_mask_and_set_register(ab3100_data, AB3100_RTC, ~(1 << 2),
> +					   alarm->enabled << 2);
> +	return err;
> +}

 just return ...


> +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(ab3100_data,
> +						    AB3100_RTC, ~(1 << 2),
> +						    1 << 2);
> +	else
> +		return ab3100_mask_and_set_register(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(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(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);
> +		dev_err(&pdev->dev, "no RTC device\n");
> +		return err;
> +	}
> +
> +	dev_info(&pdev->dev, "initialization done\n");

 no need, rtc core will emit a message.

> +
> +	return 0;
> +}
> +
> +static int __exit ab3100_rtc_remove(struct platform_device *pdev)
> +{
> +	struct rtc_device *rtc = platform_get_drvdata(pdev);
> +	struct timeval tv;
> +	unsigned long time;
> +
> +	dev_info(&pdev->dev, "rtc-ab3100: Closing down, saving date/time to " \
> +		"battery-backuped RTC\n");

 why? this should be done in userland if required.

> +	do_gettimeofday(&tv);
> +	time = timeval_to_ns(&tv);
> +	ab3100_rtc_set_mmss(&pdev->dev, time);
> +
> +	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");
> -- 
> 1.6.2.5
>

On Sun, 9 Aug 2009 23:02:20 +0200
Linus Walleij <linus.ml.walleij@gmail.com> wrote:

> 2009/7/12 Linus Walleij <linus.walleij@stericsson.com>:
> 
> > 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>
> 
> Any comments on this one? Acked-by from Alessandro atleast ?

 I just sent a quick review, sorry for the delay.