rtc: AB8500 RTC driver

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

Signed-off-by: Virupax Sadashivpetimath <virupax.sadashivpetimath@stericsson.com>
Signed-off-by: Rabin Vincent <rabin.vincent@stericsson.com>
Acked-by: Linus Walleij <linus.walleij@stericsson.com>
Acked-by: Srinidhi Kasagar <srinidhi.kasagar@stericsson.com>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Cc: Samuel Ortiz <sameo@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/rtc/Kconfig

@@ -611,6 +611,13 @@ 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
+	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

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

drivers/rtc/rtc-ab8500.c

@@ -0,0 +1,363 @@
+/*
+ * 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
+
+static const unsigned long 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 unsigned long 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)
+{
+	struct ab8500 *ab8500 = dev_get_drvdata(dev->parent);
+	unsigned long timeout = jiffies + HZ;
+	int retval, i;
+	unsigned long mins, secs;
+	unsigned char buf[ARRAY_SIZE(ab8500_rtc_time_regs)];
+
+	/* Request a data read */
+	retval = ab8500_write(ab8500, 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 (ab8500->revision == 0) {
+		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(ab8500_rtc_time_regs); i++) {
+		retval = ab8500_read(ab8500, ab8500_rtc_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[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 = ab8500_write(ab8500, ab8500_rtc_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[ARRAY_SIZE(ab8500_rtc_alarm_regs)];
+	unsigned long secs, mins;
+
+	/* 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(ab8500_rtc_alarm_regs); i++) {
+		retval = ab8500_read(ab8500, ab8500_rtc_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[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 = ab8500_write(ab8500, ab8500_rtc_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");
+
+	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");