rtc: add AB5500 RTC driver

Add a driver for the RTC block on the AB5500.  The AB5500 RTC has
similarities with both the AB8500 and the AB3100, so this driver
is made generic in order to replace the other two drivers by adding
some variant specific information.

ST-Ericsson Linux next: -
ST-Ericsson ID: WP332221
ST-Ericsson FOSS-OUT ID: Trivial

Change-Id: I35c7ee245ea68e435c800151dbb8f6e10c7abe5d
Signed-off-by: Rabin Vincent <rabin.vincent@stericsson.com>
Reviewed-on: http://gerrit.lud.stericsson.com/gerrit/19331
Reviewed-by: Vijaya Kumar K-1 <vijay.kilari@stericsson.com>
Reviewed-by: Bibek BASU <bibek.basu@stericsson.com>
Reviewed-by: Srinidhi KASAGAR <srinidhi.kasagar@stericsson.com>

3 files changed, 488 insertions, 0 deletions

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index ce2aabf5c55..799f35afb3e 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -697,6 +697,13 @@ 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_AB
+	tristate "ST-Ericsson AB5500 RTC"
+	depends on AB5500_CORE
+	help
+	  Select this to enable the ST-Ericsson AB5500 Mixed Signal IC RTC
+	  support. This chip contains a battery- and capacitor-backed RTC.
+
 config RTC_DRV_AB3100
 	tristate "ST-Ericsson AB3100 RTC"
 	depends on AB3100_CORE
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index 0ffefe877bf..cda4cd01ced 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -16,6 +16,7 @@ rtc-core-$(CONFIG_RTC_INTF_SYSFS) += rtc-sysfs.o
 # Keep the list ordered.
 
 obj-$(CONFIG_RTC_DRV_88PM860X)  += rtc-88pm860x.o
+obj-$(CONFIG_RTC_DRV_AB)	+= rtc-ab.o
 obj-$(CONFIG_RTC_DRV_AB3100)	+= rtc-ab3100.o
 obj-$(CONFIG_RTC_DRV_AB8500)	+= rtc-ab8500.o
 obj-$(CONFIG_RTC_DRV_AT32AP700X)+= rtc-at32ap700x.o
diff --git a/drivers/rtc/rtc-ab.c b/drivers/rtc/rtc-ab.c
new file mode 100644
index 00000000000..3d3c216995d
--- /dev/null
+++ b/drivers/rtc/rtc-ab.c
@@ -0,0 +1,480 @@
+/*
+ * Copyright (C) ST-Ericsson SA 2011
+ *
+ * License terms: GNU General Public License (GPL) version 2
+ * Author: Rabin Vincent <rabin.vincent@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/interrupt.h>
+#include <linux/delay.h>
+#include <linux/mfd/abx500.h>
+
+#define AB5500_RTC_CLOCK_RATE	32768
+#define AB5500_RTC		0x00
+#define AB5500_RTC_ALARM	(1 << 1)
+#define AB5500_READREQ		0x01
+#define AB5500_READREQ_REQ	0x01
+#define AB5500_AL0		0x02
+#define AB5500_TI0		0x06
+
+/**
+ * struct ab_rtc - variant specific data
+ * @irqname: optional name for the alarm interrupt resource
+ * @epoch: epoch to adjust year to
+ * @bank: AB bank where this block is present
+ * @rtc: address of the "RTC" (control) register
+ * @rtc_alarmon: mask of the alarm enable bit in the above register
+ * @ti0: address of the TI0 register.  The rest of the TI
+ * registers are assumed to contiguously follow this one.
+ * @nr_ti: number of TI* registers
+ * @al0: address of the AL0 register.  The rest of the
+ * AL registers are assumed to contiguously follow this one.
+ * @nr_al: number of AL* registers
+ * @startup: optional function to initialize the RTC
+ * @alarm_to_regs: function to convert alarm time in seconds
+ * to a list of AL register values
+ * @time_to_regs: function to convert alarm time in seconds
+ * to a list of TI register values
+ * @regs_to_alarm: function to convert a list of AL register
+ * values to the alarm time in seconds
+ * @regs_to_time: function to convert a list of TI register
+ * values to the alarm time in seconds
+ * @request_read: optional function to request a read from the TI* registers
+ * @request_write: optional function to request a write to the TI* registers
+ */
+struct ab_rtc {
+	const char *irqname;
+	unsigned int epoch;
+
+	u8 bank;
+	u8 rtc;
+	u8 rtc_alarmon;
+	u8 ti0;
+	int nr_ti;
+	u8 al0;
+	int nr_al;
+
+	int (*startup)(struct device *dev);
+	void (*alarm_to_regs)(struct device *dev, unsigned long secs, u8 *regs);
+	void (*time_to_regs)(struct device *dev, unsigned long secs, u8 *regs);
+	unsigned long (*regs_to_alarm)(struct device *dev, u8 *regs);
+	unsigned long (*regs_to_time)(struct device *dev, u8 *regs);
+	int (*request_read)(struct device *dev);
+	int (*request_write)(struct device *dev);
+};
+
+static const struct ab_rtc *to_ab_rtc(struct device *dev)
+{
+	struct platform_device *pdev = to_platform_device(dev);
+	return (struct ab_rtc *)pdev->id_entry->driver_data;
+}
+
+/* Calculate the number of seconds since year, for epoch adjustment */
+static unsigned long ab_rtc_get_elapsed_seconds(unsigned int year)
+{
+	unsigned long secs;
+	struct rtc_time tm = {
+		.tm_year = year - 1900,
+		.tm_mday = 1,
+	};
+
+	rtc_tm_to_time(&tm, &secs);
+
+	return secs;
+}
+
+static int ab5500_rtc_request_read(struct device *dev)
+{
+	const struct ab_rtc *variant = to_ab_rtc(dev);
+	unsigned long timeout;
+	int err;
+
+	err = abx500_set_register_interruptible(dev, variant->bank,
+						AB5500_READREQ,
+						AB5500_READREQ_REQ);
+	if (err < 0)
+		return err;
+
+	timeout = jiffies + HZ;
+	while (time_before(jiffies, timeout)) {
+		u8 value;
+
+		err = abx500_get_register_interruptible(dev, variant->bank,
+				AB5500_READREQ, &value);
+		if (err < 0)
+			return err;
+
+		if (!(value & AB5500_READREQ_REQ))
+			return 0;
+
+		msleep(1);
+	}
+
+	return -EIO;
+}
+
+static void
+ab5500_rtc_time_to_regs(struct device *dev, unsigned long secs, u8 *regs)
+{
+	unsigned long mins = secs / 60;
+	u64 fat_time;
+
+	secs %= 60;
+
+	fat_time = secs * AB5500_RTC_CLOCK_RATE;
+	fat_time |= (u64)mins << 21;
+
+	regs[0] = (fat_time) & 0xFF;
+	regs[1] = (fat_time >> 8) & 0xFF;
+	regs[2] = (fat_time >> 16) & 0xFF;
+	regs[3] = (fat_time >> 24) & 0xFF;
+	regs[4] = (fat_time >> 32) & 0xFF;
+	regs[5] = (fat_time >> 40) & 0xFF;
+}
+
+static unsigned long
+ab5500_rtc_regs_to_time(struct device *dev, u8 *regs)
+{
+	u64 fat_time = ((u64)regs[5] << 40) | ((u64)regs[4] << 32) |
+		       (regs[3] << 24) | (regs[2] << 16) |
+		       (regs[1] << 8) | regs[0];
+	unsigned long secs = (fat_time & 0x1fffff) / AB5500_RTC_CLOCK_RATE;
+	unsigned long mins = fat_time >> 21;
+
+	return mins * 60 + secs;
+}
+
+static void
+ab5500_rtc_alarm_to_regs(struct device *dev, unsigned long secs, u8 *regs)
+{
+	unsigned long mins = secs / 60;
+
+#ifdef CONFIG_ANDROID
+	/*
+	 * Needed because Android believes all hw have a wake-up resolution in
+	 * seconds.
+	 */
+	mins++;
+#endif
+
+	regs[0] = mins & 0xFF;
+	regs[1] = (mins >> 8) & 0xFF;
+	regs[2] = (mins >> 16) & 0xFF;
+}
+
+static unsigned long
+ab5500_rtc_regs_to_alarm(struct device *dev, u8 *regs)
+{
+	unsigned long mins = (regs[2] << 16) | (regs[1] << 8) | regs[0];
+	unsigned long secs = mins * 60;
+
+	return secs;
+}
+
+static const struct ab_rtc ab5500_rtc = {
+	.irqname	= "RTC_Alarm",
+	.bank		= AB5500_BANK_RTC,
+	.rtc		= AB5500_RTC,
+	.rtc_alarmon	= AB5500_RTC_ALARM,
+	.ti0		= AB5500_TI0,
+	.nr_ti		= 6,
+	.al0		= AB5500_AL0,
+	.nr_al		= 3,
+	.epoch		= 2000,
+	.time_to_regs	= ab5500_rtc_time_to_regs,
+	.regs_to_time	= ab5500_rtc_regs_to_time,
+	.alarm_to_regs	= ab5500_rtc_alarm_to_regs,
+	.regs_to_alarm	= ab5500_rtc_regs_to_alarm,
+	.request_read	= ab5500_rtc_request_read,
+};
+
+static int ab_rtc_request_read(struct device *dev)
+{
+	const struct ab_rtc *variant = to_ab_rtc(dev);
+
+	if (!variant->request_read)
+		return 0;
+
+	return variant->request_read(dev);
+}
+
+static int ab_rtc_request_write(struct device *dev)
+{
+	const struct ab_rtc *variant = to_ab_rtc(dev);
+
+	if (!variant->request_write)
+		return 0;
+
+	return variant->request_write(dev);
+}
+
+static bool ab_rtc_valid_time(struct device *dev, struct rtc_time *time)
+{
+	const struct ab_rtc *variant = to_ab_rtc(dev);
+
+	if (!variant->epoch)
+		return true;
+
+	return time->tm_year >= variant->epoch - 1900;
+}
+
+static int
+ab_rtc_tm_to_time(struct device *dev, struct rtc_time *tm, unsigned long *secs)
+{
+	const struct ab_rtc *variant = to_ab_rtc(dev);
+
+	rtc_tm_to_time(tm, secs);
+
+	if (variant->epoch)
+		*secs -= ab_rtc_get_elapsed_seconds(variant->epoch);
+
+	return 0;
+}
+
+static int
+ab_rtc_time_to_tm(struct device *dev, unsigned long secs, struct rtc_time *tm)
+{
+	const struct ab_rtc *variant = to_ab_rtc(dev);
+
+	if (variant->epoch)
+		secs += ab_rtc_get_elapsed_seconds(variant->epoch);
+
+	rtc_time_to_tm(secs, tm);
+
+	return 0;
+}
+
+static int ab_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+	const struct ab_rtc *variant = to_ab_rtc(dev);
+	unsigned char buf[variant->nr_ti];
+	unsigned long secs;
+	int err;
+
+	err = ab_rtc_request_read(dev);
+	if (err)
+		return err;
+
+	err = abx500_get_register_page_interruptible(dev, variant->bank,
+						     variant->ti0,
+						     buf, variant->nr_ti);
+	if (err)
+		return err;
+
+	secs = variant->regs_to_time(dev, buf);
+	ab_rtc_time_to_tm(dev, secs, tm);
+
+	return rtc_valid_tm(tm);
+}
+
+static int ab_rtc_set_time(struct device *dev, struct rtc_time *tm)
+{
+	const struct ab_rtc *variant = to_ab_rtc(dev);
+	unsigned char buf[variant->nr_ti];
+	unsigned long secs;
+	u8 reg = variant->ti0;
+	int err;
+	int i;
+
+	if (!ab_rtc_valid_time(dev, tm))
+		return -EINVAL;
+
+	ab_rtc_tm_to_time(dev, tm, &secs);
+	variant->time_to_regs(dev, secs, buf);
+
+	for (i = 0; i < variant->nr_ti; i++, reg++) {
+		err = abx500_set_register_interruptible(dev, variant->bank,
+							reg, buf[i]);
+		if (err)
+			return err;
+	}
+
+	return ab_rtc_request_write(dev);
+}
+
+static int ab_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
+{
+	const struct ab_rtc *variant = to_ab_rtc(dev);
+	unsigned long secs;
+	u8 buf[variant->nr_al];
+	u8 rtcval;
+	int err;
+
+	err = abx500_get_register_interruptible(dev, variant->bank,
+						variant->rtc, &rtcval);
+	if (err)
+		return err;
+
+	alarm->enabled = !!(rtcval & variant->rtc_alarmon);
+	alarm->pending = 0;
+
+	err = abx500_get_register_page_interruptible(dev, variant->bank,
+						     variant->al0, buf,
+						     variant->nr_al);
+	if (err)
+		return err;
+
+	secs = variant->regs_to_alarm(dev, buf);
+	ab_rtc_time_to_tm(dev, secs, &alarm->time);
+
+	return rtc_valid_tm(&alarm->time);
+}
+
+static int ab_rtc_alarm_enable(struct device *dev, unsigned int enabled)
+{
+	const struct ab_rtc *variant = to_ab_rtc(dev);
+	u8 mask = variant->rtc_alarmon;
+	u8 value = enabled ? mask : 0;
+
+	return abx500_mask_and_set_register_interruptible(dev, variant->bank,
+							  variant->rtc, mask,
+							  value);
+}
+
+static int ab_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
+{
+	const struct ab_rtc *variant = to_ab_rtc(dev);
+	unsigned char buf[variant->nr_al];
+	unsigned long secs;
+	u8 reg = variant->al0;
+	int err;
+	int i;
+
+	if (!ab_rtc_valid_time(dev, &alarm->time))
+		return -EINVAL;
+
+	ab_rtc_tm_to_time(dev, &alarm->time, &secs);
+	variant->alarm_to_regs(dev, secs, buf);
+
+	/*
+	 * Disable alarm first.  Otherwise the RTC may not detect an alarm
+	 * reprogrammed for the same time without disabling the alarm in
+	 * between the programmings.
+	 */
+	err = ab_rtc_alarm_enable(dev, false);
+	if (err)
+		return err;
+
+	for (i = 0; i < variant->nr_al; i++, reg++) {
+		err = abx500_set_register_interruptible(dev, variant->bank,
+							reg, buf[i]);
+		if (err)
+			return err;
+	}
+
+	return ab_rtc_alarm_enable(dev, true);
+}
+
+static const struct rtc_class_ops ab_rtc_ops = {
+	.read_time		= ab_rtc_read_time,
+	.set_time		= ab_rtc_set_time,
+	.read_alarm		= ab_rtc_read_alarm,
+	.set_alarm		= ab_rtc_set_alarm,
+	.alarm_irq_enable	= ab_rtc_alarm_enable,
+};
+
+static irqreturn_t ab_rtc_irq(int irq, void *dev_id)
+{
+	unsigned long events = RTC_IRQF | RTC_AF;
+	struct rtc_device *rtc = dev_id;
+
+	rtc_update_irq(rtc, 1, events);
+
+	return IRQ_HANDLED;
+}
+
+static int __devinit ab_rtc_probe(struct platform_device *pdev)
+{
+	const struct ab_rtc *variant = to_ab_rtc(&pdev->dev);
+	int err;
+	struct rtc_device *rtc;
+	int irq = -ENXIO;
+
+	if (variant->irqname) {
+		irq = platform_get_irq_byname(pdev, variant->irqname);
+		if (irq < 0)
+			return irq;
+	}
+
+	if (variant->startup) {
+		err = variant->startup(&pdev->dev);
+		if (err)
+			return err;
+	}
+
+	rtc = rtc_device_register("ab8500-rtc", &pdev->dev, &ab_rtc_ops,
+			THIS_MODULE);
+	if (IS_ERR(rtc)) {
+		dev_err(&pdev->dev, "Registration failed\n");
+		err = PTR_ERR(rtc);
+		return err;
+	}
+
+	if (irq >= 0) {
+		err = request_any_context_irq(irq, ab_rtc_irq,
+					      IRQF_NO_SUSPEND,
+					      pdev->id_entry->name,
+					      rtc);
+		if (err < 0) {
+			dev_err(&pdev->dev, "could not get irq: %d\n", err);
+			goto out_unregister;
+		}
+	}
+
+	platform_set_drvdata(pdev, rtc);
+
+	return 0;
+
+out_unregister:
+	rtc_device_unregister(rtc);
+	return err;
+}
+
+static int __devexit ab_rtc_remove(struct platform_device *pdev)
+{
+	const struct ab_rtc *variant = to_ab_rtc(&pdev->dev);
+	struct rtc_device *rtc = platform_get_drvdata(pdev);
+	int irq = platform_get_irq_byname(pdev, variant->irqname);
+
+	if (irq >= 0)
+		free_irq(irq, rtc);
+	rtc_device_unregister(rtc);
+	platform_set_drvdata(pdev, NULL);
+
+	return 0;
+}
+
+static struct platform_device_id ab_rtc_id_table[] = {
+	{ "ab5500-rtc", (kernel_ulong_t)&ab5500_rtc, },
+	{ },
+};
+MODULE_DEVICE_TABLE(platform, ab_rtc_id_table);
+
+static struct platform_driver ab_rtc_driver = {
+	.driver.name	= "ab-rtc",
+	.driver.owner	= THIS_MODULE,
+	.id_table	= ab_rtc_id_table,
+	.probe		= ab_rtc_probe,
+	.remove		= __devexit_p(ab_rtc_remove),
+};
+
+static int __init ab_rtc_init(void)
+{
+	return platform_driver_register(&ab_rtc_driver);
+}
+module_init(ab_rtc_init);
+
+static void __exit ab_rtc_exit(void)
+{
+	platform_driver_unregister(&ab_rtc_driver);
+}
+module_exit(ab_rtc_exit);
+
+MODULE_AUTHOR("Rabin Vincent <rabin.vincent@stericsson.com>");
+MODULE_DESCRIPTION("AB5500 RTC Driver");
+MODULE_LICENSE("GPL v2");