Message-ID: <20100526121150.GA17197@bnru02.bnr.st.com>
Date:	Wed, 26 May 2010 17:41:51 +0530
From:	Rabin VINCENT <rabin.vincent@...ricsson.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Alessandro Zummo <a.zummo@...ertech.it>,
	"rtc-linux@...glegroups.com" <rtc-linux@...glegroups.com>,
	Samuel Ortiz <sameo@...ux.intel.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	STEricsson_nomadik_linux <STEricsson_nomadik_linux@...t.st.com>,
	Virupax SADASHIVPETIMATH 
	<virupax.sadashivpetimath@...ricsson.com>,
	Linus WALLEIJ <linus.walleij@...ricsson.com>,
	Srinidhi KASAGAR <srinidhi.kasagar@...ricsson.com>
Subject: Re: [PATCH] rtc: AB8500 RTC driver

On Tue, May 25, 2010 at 22:51:59 +0200, Andrew Morton wrote:
> On Fri, 21 May 2010 20:26:36 +0530
> Rabin Vincent <rabin.vincent@...ricsson.com> wrote:
> > +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..

Several other drivers do a platform_get_irq() in their remove().  We'd
have probably stored it locally anyway, but this driver actually gets by
without allocating any private storage, so it didn't seem necessary to
add some just for this.

We've removed the unnecessary "if (irq >= 0)" condition before
free_irq() to make it clear to the reader that the
platform_get_irq_byname() call won't fail.

All your other comments should be addressed in the updated patch below.
Thanks.

Rabin

>From ea22b7052c86a2f22b8f615291dd7bfda5634f46 Mon Sep 17 00:00:00 2001
From: Virupax Sadashivpetimath <virupax.sadashivpetimath@...ricsson.com>
Date: Fri, 30 Apr 2010 09:17:07 +0530
Subject: [PATCHv2] 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.

Acked-by: Linus Walleij <linus.walleij@...ricsson.com>
Acked-by: Srinidhi Kasagar <srinidhi.kasagar@...ricsson.com>
Signed-off-by: Virupax Sadashivpetimath <virupax.sadashivpetimath@...ricsson.com>
Signed-off-by: Rabin Vincent <rabin.vincent@...ricsson.com>
---
 drivers/rtc/Kconfig      |    7 +
 drivers/rtc/Makefile     |    1 +
 drivers/rtc/rtc-ab8500.c |  363 ++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 371 insertions(+), 0 deletions(-)
 create mode 100644 drivers/rtc/rtc-ab8500.c

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index 50ac047..e3ae61c 100644
--- a/drivers/rtc/Kconfig
+++ b/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
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index 245311a..5adbba7 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..2fda031
--- /dev/null
+++ b/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@...ricsson.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@...ricsson.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@...ricsson.com>");
+MODULE_DESCRIPTION("AB8500 RTC Driver");
+MODULE_LICENSE("GPL v2");
-- 
1.6.3.3

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