diff mbox

rtc: AB8500 RTC driver

Message ID 1274453796-9141-1-git-send-email-rabin.vincent@stericsson.com
State Accepted
Headers show

Commit Message

Rabin Vincent May 21, 2010, 2:56 p.m. UTC
From: Virupax Sadashivpetimath <virupax.sadashivpetimath@stericsson.com>

Add a driver for the RTC on the AB8500 power management chip.  This is a
client of the AB8500 MFD driver.

Acked-by: Linus Walleij <linus.walleij@stericsson.com>
Acked-by: Srinidhi Kasagar <srinidhi.kasagar@stericsson.com>
Signed-off-by: Virupax Sadashivpetimath <virupax.sadashivpetimath@stericsson.com>
Signed-off-by: Rabin Vincent <rabin.vincent@stericsson.com>
---
 drivers/rtc/Kconfig      |    8 +
 drivers/rtc/Makefile     |    1 +
 drivers/rtc/rtc-ab8500.c |  366 ++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 375 insertions(+), 0 deletions(-)
 create mode 100644 drivers/rtc/rtc-ab8500.c

Comments

Andrew Morton May 25, 2010, 8:51 p.m. UTC | #1
On Fri, 21 May 2010 20:26:36 +0530
Rabin Vincent <rabin.vincent@stericsson.com> wrote:

> From: Virupax Sadashivpetimath <virupax.sadashivpetimath@stericsson.com>
> 
> Add a driver for the RTC on the AB8500 power management chip.  This is a
> client of the AB8500 MFD driver.
> 
>
> ...
>
> --- a/drivers/rtc/Kconfig
> +++ b/drivers/rtc/Kconfig
> @@ -611,6 +611,14 @@ config RTC_DRV_AB3100
>  	  Select this to enable the ST-Ericsson AB3100 Mixed Signal IC RTC
>  	  support. This chip contains a battery- and capacitor-backed RTC.
>  
> +config RTC_DRV_AB8500
> +	tristate "ST-Ericsson AB8500 RTC"
> +	depends on AB8500_CORE
> +	default y

Really?  So all AB8500_CORE users will get to include this driver in
their builds just by running `make oldconfig'?

> +	help
> +	  Select this to enable the ST-Ericsson AB8500 power management IC RTC
> +	  support. This chip contains a battery- and capacitor-backed RTC.
> +
>
> ...
>
> +static unsigned long get_elapsed_seconds(int year)
> +{
> +	unsigned long secs;
> +	struct rtc_time tm;
> +
> +	memset(&tm, 0, sizeof(tm));
> +	tm.tm_year = year - 1900;
> +	tm.tm_mon  = 0;
> +	tm.tm_mday  = 1;

It would be neater to do

	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)
> +{
> +	struct ab8500 *ab8500 = dev_get_drvdata(dev->parent);
> +	unsigned long timeout = jiffies + HZ;
> +	int retval, i;
> +	unsigned long mins, secs;
> +	unsigned char buf[5];
> +	const unsigned long 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};

iirc, the compiler will quietly treat this as `static const', which is
what we want.

> +	/* Request a data read */
> +	retval = ab8500_write(ab8500, AB8500_RTC_READ_REQ_REG,
> +			      RTC_READ_REQUEST);
> +	if (retval < 0)
> +		return retval;
> +
> +	if (!ab8500->revision) {
> +		msleep(1);

This bit needs a comment.  Because there's no way of understanding it
by reading the code!

> +	} else {
> +		/* Wait for some cycles after enabling the rtc read in ab8500 */
> +		while (time_before(jiffies, timeout)) {
> +			retval = ab8500_read(ab8500, AB8500_RTC_READ_REQ_REG);
> +			if (retval < 0)
> +				return retval;
> +
> +			if (!(retval & RTC_READ_REQUEST))
> +				break;
> +
> +			msleep(1);
> +		}
> +	}
> +
> +	/* Read the Watchtime registers */
> +	for (i = 0; i < ARRAY_SIZE(time_regs); i++) {
> +		retval = ab8500_read(ab8500, time_regs[i]);
> +		if (retval < 0)
> +			return retval;
> +		buf[i] = retval;
> +	}
> +
> +	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)
> +{
> +	struct ab8500 *ab8500 = dev_get_drvdata(dev->parent);
> +	int retval, i;
> +	unsigned char buf[5];
> +	unsigned long no_secs, no_mins, secs = 0;
> +	const unsigned long 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};
> +
> +	if (tm->tm_year < (AB8500_RTC_EPOCH - 1900)) {
> +		dev_err(dev, "year should be equal to or more than %d\n",
> +				AB8500_RTC_EPOCH);

hm, is this really worth the console spam?

"equal to or greater than" would sound more mathematical ;)

> +		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(time_regs); i++) {
> +		retval = ab8500_write(ab8500, time_regs[i], buf[i]);
> +		if (retval < 0)
> +			return retval;
> +	}
> +
> +	/* Request a data write */
> +	return ab8500_write(ab8500, AB8500_RTC_READ_REQ_REG, RTC_WRITE_REQUEST);
> +}
> +
>
> ...
>
> +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");

Seems a bit fragile.  I guess that platform_get_irq_byname("ALARM")
will always return the same value, but still.  Would it be better to
store the irq number in private storage?  Unsure..


> +	if (irq >= 0)
> +		free_irq(irq, rtc);
> +
> +	rtc_device_unregister(rtc);
> +	platform_set_drvdata(pdev, NULL);
> +
> +	return 0;
> +}
> +
>
> ...
>
diff mbox

Patch

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index 6a13037..91be977 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -611,6 +611,14 @@  config RTC_DRV_AB3100
 	  Select this to enable the ST-Ericsson AB3100 Mixed Signal IC RTC
 	  support. This chip contains a battery- and capacitor-backed RTC.
 
+config RTC_DRV_AB8500
+	tristate "ST-Ericsson AB8500 RTC"
+	depends on AB8500_CORE
+	default y
+	help
+	  Select this to enable the ST-Ericsson AB8500 power management IC RTC
+	  support. This chip contains a battery- and capacitor-backed RTC.
+
 config RTC_DRV_NUC900
 	tristate "NUC910/NUC920 RTC driver"
 	depends on RTC_CLASS && ARCH_W90X900
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index 44ef194..d3377d8 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -18,6 +18,7 @@  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_AB8500)	+= rtc-ab8500.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-ab8500.c b/drivers/rtc/rtc-ab8500.c
new file mode 100644
index 0000000..d06982f
--- /dev/null
+++ b/drivers/rtc/rtc-ab8500.c
@@ -0,0 +1,366 @@ 
+/*
+ * 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/ab8500.h>
+#include <linux/delay.h>
+
+#define AB8500_RTC_SOFF_STAT_REG	0x0F00
+#define AB8500_RTC_CC_CONF_REG		0x0F01
+#define AB8500_RTC_READ_REQ_REG		0x0F02
+#define AB8500_RTC_WATCH_TSECMID_REG	0x0F03
+#define AB8500_RTC_WATCH_TSECHI_REG	0x0F04
+#define AB8500_RTC_WATCH_TMIN_LOW_REG	0x0F05
+#define AB8500_RTC_WATCH_TMIN_MID_REG	0x0F06
+#define AB8500_RTC_WATCH_TMIN_HI_REG	0x0F07
+#define AB8500_RTC_ALRM_MIN_LOW_REG	0x0F08
+#define AB8500_RTC_ALRM_MIN_MID_REG	0x0F09
+#define AB8500_RTC_ALRM_MIN_HI_REG	0x0F0A
+#define AB8500_RTC_STAT_REG		0x0F0B
+#define AB8500_RTC_BKUP_CHG_REG		0x0F0C
+#define AB8500_RTC_FORCE_BKUP_REG	0x0F0D
+#define AB8500_RTC_CALIB_REG		0x0F0E
+#define AB8500_RTC_SWITCH_STAT_REG	0x0F0F
+#define AB8500_REV_REG			0x1080
+
+/* 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
+
+/* 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;
+
+	memset(&tm, 0, sizeof(tm));
+	tm.tm_year = year - 1900;
+	tm.tm_mon  = 0;
+	tm.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)
+{
+	struct ab8500 *ab8500 = dev_get_drvdata(dev->parent);
+	unsigned long timeout = jiffies + HZ;
+	int retval, i;
+	unsigned long mins, secs;
+	unsigned char buf[5];
+	const unsigned long 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};
+
+	/* Request a data read */
+	retval = ab8500_write(ab8500, AB8500_RTC_READ_REQ_REG,
+			      RTC_READ_REQUEST);
+	if (retval < 0)
+		return retval;
+
+	if (!ab8500->revision) {
+		msleep(1);
+	} else {
+		/* Wait for some cycles after enabling the rtc read in ab8500 */
+		while (time_before(jiffies, timeout)) {
+			retval = ab8500_read(ab8500, AB8500_RTC_READ_REQ_REG);
+			if (retval < 0)
+				return retval;
+
+			if (!(retval & RTC_READ_REQUEST))
+				break;
+
+			msleep(1);
+		}
+	}
+
+	/* Read the Watchtime registers */
+	for (i = 0; i < ARRAY_SIZE(time_regs); i++) {
+		retval = ab8500_read(ab8500, time_regs[i]);
+		if (retval < 0)
+			return retval;
+		buf[i] = retval;
+	}
+
+	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)
+{
+	struct ab8500 *ab8500 = dev_get_drvdata(dev->parent);
+	int retval, i;
+	unsigned char buf[5];
+	unsigned long no_secs, no_mins, secs = 0;
+	const unsigned long 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};
+
+	if (tm->tm_year < (AB8500_RTC_EPOCH - 1900)) {
+		dev_err(dev, "year should be equal to or more 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(time_regs); i++) {
+		retval = ab8500_write(ab8500, time_regs[i], buf[i]);
+		if (retval < 0)
+			return retval;
+	}
+
+	/* Request a data write */
+	return ab8500_write(ab8500, AB8500_RTC_READ_REQ_REG, RTC_WRITE_REQUEST);
+}
+
+static int ab8500_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
+{
+	struct ab8500 *ab8500 = dev_get_drvdata(dev->parent);
+	int retval, i;
+	int rtc_ctrl;
+	unsigned char buf[3];
+	unsigned long secs, mins;
+	const unsigned long alarm_regs[] = {AB8500_RTC_ALRM_MIN_HI_REG,
+		AB8500_RTC_ALRM_MIN_MID_REG, AB8500_RTC_ALRM_MIN_LOW_REG};
+
+	/* Check if the alarm is enabled or not */
+	rtc_ctrl = ab8500_read(ab8500, AB8500_RTC_STAT_REG);
+	if (rtc_ctrl < 0)
+		return rtc_ctrl;
+
+	if (rtc_ctrl & RTC_ALARM_ENA)
+		alarm->enabled = 1;
+	else
+		alarm->enabled = 0;
+
+	alarm->pending = 0;
+
+	for (i = 0; i < ARRAY_SIZE(alarm_regs); i++) {
+		retval = ab8500_read(ab8500, alarm_regs[i]);
+		if (retval < 0)
+			return retval;
+		buf[i] = retval;
+	}
+
+	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)
+{
+	struct ab8500 *ab8500 = dev_get_drvdata(dev->parent);
+
+	return ab8500_set_bits(ab8500, 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)
+{
+	struct ab8500 *ab8500 = dev_get_drvdata(dev->parent);
+	int retval, i;
+	unsigned char buf[3];
+	unsigned long mins, secs = 0;
+	const unsigned long alarm_regs[] = {AB8500_RTC_ALRM_MIN_HI_REG,
+		AB8500_RTC_ALRM_MIN_MID_REG, AB8500_RTC_ALRM_MIN_LOW_REG};
+
+	if (alarm->time.tm_year < (AB8500_RTC_EPOCH - 1900)) {
+		dev_err(dev, "year should be equal to or more 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(alarm_regs); i++) {
+		retval = ab8500_write(ab8500, alarm_regs[i], buf[i]);
+		if (retval < 0)
+			return retval;
+	}
+
+	return ab8500_rtc_irq_enable(dev, alarm->enabled);
+}
+
+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)
+{
+	struct ab8500 *ab8500 = dev_get_drvdata(pdev->dev.parent);
+	int err;
+	struct rtc_device *rtc;
+	int rtc_ctrl;
+	int irq;
+
+	irq = platform_get_irq_byname(pdev, "ALARM");
+	if (irq < 0)
+		return irq;
+
+	/* For RTC supply test */
+	err = ab8500_set_bits(ab8500, AB8500_RTC_STAT_REG, RTC_STATUS_DATA,
+			RTC_STATUS_DATA);
+	if (err < 0)
+		return err;
+
+	/* Wait for reset by the PorRtc */
+	msleep(1);
+
+	rtc_ctrl = ab8500_read(ab8500, AB8500_RTC_STAT_REG);
+	if (rtc_ctrl < 0)
+		return rtc_ctrl;
+
+	/* Check if the RTC Supply fails */
+	if (!(rtc_ctrl & RTC_STATUS_DATA)) {
+		dev_err(&pdev->dev, "RTC supply failure\n");
+		return -ENODEV;
+	}
+
+	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, 0,
+				   "ab8500-rtc", rtc);
+	if (err < 0) {
+		rtc_device_unregister(rtc);
+		return err;
+	}
+
+	platform_set_drvdata(pdev, rtc);
+
+	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");
+
+	if (irq >= 0)
+		free_irq(irq, rtc);
+
+	rtc_device_unregister(rtc);
+	platform_set_drvdata(pdev, NULL);
+
+	return 0;
+}
+
+static struct platform_driver ab8500_rtc_driver = {
+	.driver = {
+		.name = "ab8500-rtc",
+		.owner = THIS_MODULE,
+	},
+	.probe	= ab8500_rtc_probe,
+	.remove = __devexit_p(ab8500_rtc_remove),
+};
+
+static int __init ab8500_rtc_init(void)
+{
+	return platform_driver_register(&ab8500_rtc_driver);
+}
+
+static void __exit ab8500_rtc_exit(void)
+{
+	platform_driver_unregister(&ab8500_rtc_driver);
+}
+
+module_init(ab8500_rtc_init);
+module_exit(ab8500_rtc_exit);
+MODULE_AUTHOR("Virupax Sadashivpetimath <virupax.sadashivpetimath@stericsson.com>");
+MODULE_DESCRIPTION("AB8500 RTC Driver");
+MODULE_LICENSE("GPL v2");