rtc/tpo: Driver to support rtc and wakeup on PowerNV platform

The patch implements the OPAL rtc driver that binds with the rtc
driver subsystem. The driver uses the platform device infrastructure
to probe the rtc device and register it to rtc class framework. The
'wakeup' is supported depending upon the property 'has-tpo' present
in the OF node. It provides a way to load the generic rtc driver in
in the absence of an OPAL driver.

The patch also moves the existing OPAL rtc get/set time interfaces to the
new driver and exposes the necessary OPAL calls using EXPORT_SYMBOL_GPL.

Test results:
-------------
Host:
[root@tul169p1 ~]# ls -l /sys/class/rtc/
total 0
lrwxrwxrwx 1 root root 0 Oct 14 03:07 rtc0 -> ../../devices/opal-rtc/rtc/rtc0
[root@tul169p1 ~]# cat /sys/devices/opal-rtc/rtc/rtc0/time
08:10:07
[root@tul169p1 ~]# echo `date '+%s' -d '+ 2 minutes'` > /sys/class/rtc/rtc0/wakealarm
[root@tul169p1 ~]# cat /sys/class/rtc/rtc0/wakealarm
1413274345
[root@tul169p1 ~]#

FSP:
$ smgr mfgState
standby
$ rtim timeofday

System time is valid: 2014/10/14 08:12:04.225115

$ smgr mfgState
ipling
$

CC: devicetree@vger.kernel.org
CC: tglx@linutronix.de
CC: rtc-linux@googlegroups.com
CC: a.zummo@towertech.it
Signed-off-by: Neelesh Gupta <neelegup@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

3 files changed, 273 insertions, 0 deletions

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index 6dd12dd..c8f0ec7 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -979,6 +979,17 @@ config RTC_DRV_NUC900
 	  If you say yes here you get support for the RTC subsystem of the
 	  NUC910/NUC920 used in embedded systems.
 
+config RTC_DRV_OPAL
+	tristate "IBM OPAL RTC driver"
+	depends on PPC_POWERNV
+	default y
+	help
+	  If you say yes here you get support for the PowerNV platform RTC
+	  driver based on OPAL interfaces.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called rtc-opal.
+
 comment "on-CPU RTC drivers"
 
 config RTC_DRV_DAVINCI
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index b188323..c8ef3e1 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -92,6 +92,7 @@ obj-$(CONFIG_RTC_DRV_MSM6242)	+= rtc-msm6242.o
 obj-$(CONFIG_RTC_DRV_MPC5121)	+= rtc-mpc5121.o
 obj-$(CONFIG_RTC_DRV_MV)	+= rtc-mv.o
 obj-$(CONFIG_RTC_DRV_NUC900)	+= rtc-nuc900.o
+obj-$(CONFIG_RTC_DRV_OPAL)	+= rtc-opal.o
 obj-$(CONFIG_RTC_DRV_OMAP)	+= rtc-omap.o
 obj-$(CONFIG_RTC_DRV_PALMAS)	+= rtc-palmas.o
 obj-$(CONFIG_RTC_DRV_PCAP)	+= rtc-pcap.o
diff --git a/drivers/rtc/rtc-opal.c b/drivers/rtc/rtc-opal.c
new file mode 100644
index 0000000..95f6521
--- /dev/null
+++ b/drivers/rtc/rtc-opal.c
@@ -0,0 +1,261 @@
+/*
+ * IBM OPAL RTC driver
+ * Copyright (C) 2014 IBM
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.
+ */
+
+#define DRVNAME		"rtc-opal"
+#define pr_fmt(fmt)	DRVNAME ": " fmt
+
+#include <linux/module.h>
+#include <linux/err.h>
+#include <linux/rtc.h>
+#include <linux/delay.h>
+#include <linux/bcd.h>
+#include <linux/platform_device.h>
+#include <linux/of.h>
+#include <asm/opal.h>
+#include <asm/firmware.h>
+
+static void opal_to_tm(u32 y_m_d, u64 h_m_s_ms, struct rtc_time *tm)
+{
+	tm->tm_year = ((bcd2bin(y_m_d >> 24) * 100) +
+		       bcd2bin((y_m_d >> 16) & 0xff)) - 1900;
+	tm->tm_mon  = bcd2bin((y_m_d >> 8) & 0xff) - 1;
+	tm->tm_mday = bcd2bin(y_m_d & 0xff);
+	tm->tm_hour = bcd2bin((h_m_s_ms >> 56) & 0xff);
+	tm->tm_min  = bcd2bin((h_m_s_ms >> 48) & 0xff);
+	tm->tm_sec  = bcd2bin((h_m_s_ms >> 40) & 0xff);
+
+	GregorianDay(tm);
+}
+
+static void tm_to_opal(struct rtc_time *tm, u32 *y_m_d, u64 *h_m_s_ms)
+{
+	*y_m_d |= ((u32)bin2bcd((tm->tm_year + 1900) / 100)) << 24;
+	*y_m_d |= ((u32)bin2bcd((tm->tm_year + 1900) % 100)) << 16;
+	*y_m_d |= ((u32)bin2bcd((tm->tm_mon + 1))) << 8;
+	*y_m_d |= ((u32)bin2bcd(tm->tm_mday));
+
+	*h_m_s_ms |= ((u64)bin2bcd(tm->tm_hour)) << 56;
+	*h_m_s_ms |= ((u64)bin2bcd(tm->tm_min)) << 48;
+	*h_m_s_ms |= ((u64)bin2bcd(tm->tm_sec)) << 40;
+}
+
+static int opal_get_rtc_time(struct device *dev, struct rtc_time *tm)
+{
+	long rc = OPAL_BUSY;
+	u32 y_m_d;
+	u64 h_m_s_ms;
+	__be32 __y_m_d;
+	__be64 __h_m_s_ms;
+
+	while (rc == OPAL_BUSY || rc == OPAL_BUSY_EVENT) {
+		rc = opal_rtc_read(&__y_m_d, &__h_m_s_ms);
+		if (rc == OPAL_BUSY_EVENT)
+			opal_poll_events(NULL);
+		else
+			msleep(10);
+	}
+
+	if (rc != OPAL_SUCCESS)
+		return -EIO;
+
+	y_m_d = be32_to_cpu(__y_m_d);
+	h_m_s_ms = be64_to_cpu(__h_m_s_ms);
+	opal_to_tm(y_m_d, h_m_s_ms, tm);
+
+	return 0;
+}
+
+static int opal_set_rtc_time(struct device *dev, struct rtc_time *tm)
+{
+	long rc = OPAL_BUSY;
+	u32 y_m_d = 0;
+	u64 h_m_s_ms = 0;
+
+	tm_to_opal(tm, &y_m_d, &h_m_s_ms);
+	while (rc == OPAL_BUSY || rc == OPAL_BUSY_EVENT) {
+		rc = opal_rtc_write(y_m_d, h_m_s_ms);
+		if (rc == OPAL_BUSY_EVENT)
+			opal_poll_events(NULL);
+		else
+			msleep(10);
+	}
+
+	return rc == OPAL_SUCCESS ? 0 : -EIO;
+}
+
+/*
+ * TPO	Timed Power-On
+ *
+ * TPO get/set OPAL calls care about the hour and min and to make it consistent
+ * with the rtc utility time conversion functions, we use the 'u64' to store
+ * its value and perform bit shift by 32 before use..
+ */
+static int opal_get_tpo_time(struct device *dev, struct rtc_wkalrm *alarm)
+{
+	__be32 __y_m_d, __h_m;
+	struct opal_msg msg;
+	int rc, token;
+	u64 h_m_s_ms;
+	u32 y_m_d;
+
+	token = opal_async_get_token_interruptible();
+	if (token < 0) {
+		if (token != -ERESTARTSYS)
+			pr_err("Failed to get the async token\n");
+
+		return token;
+	}
+
+	rc = opal_tpo_read(token, &__y_m_d, &__h_m);
+	if (rc != OPAL_ASYNC_COMPLETION) {
+		rc = -EIO;
+		goto exit;
+	}
+
+	rc = opal_async_wait_response(token, &msg);
+	if (rc) {
+		rc = -EIO;
+		goto exit;
+	}
+
+	rc = be64_to_cpu(msg.params[1]);
+	if (rc != OPAL_SUCCESS) {
+		rc = -EIO;
+		goto exit;
+	}
+
+	y_m_d = be32_to_cpu(__y_m_d);
+	h_m_s_ms = ((u64)be32_to_cpu(__h_m) << 32);
+	opal_to_tm(y_m_d, h_m_s_ms, &alarm->time);
+
+exit:
+	opal_async_release_token(token);
+	return rc;
+}
+
+/* Set Timed Power-On */
+static int opal_set_tpo_time(struct device *dev, struct rtc_wkalrm *alarm)
+{
+	u64 h_m_s_ms = 0, token;
+	struct opal_msg msg;
+	u32 y_m_d = 0;
+	int rc;
+
+	tm_to_opal(&alarm->time, &y_m_d, &h_m_s_ms);
+
+	token = opal_async_get_token_interruptible();
+	if (token < 0) {
+		if (token != -ERESTARTSYS)
+			pr_err("Failed to get the async token\n");
+
+		return token;
+	}
+
+	/* TPO, we care about hour and minute */
+	rc = opal_tpo_write(token, y_m_d,
+			    (u32)((h_m_s_ms >> 32) & 0xffff0000));
+	if (rc != OPAL_ASYNC_COMPLETION) {
+		rc = -EIO;
+		goto exit;
+	}
+
+	rc = opal_async_wait_response(token, &msg);
+	if (rc) {
+		rc = -EIO;
+		goto exit;
+	}
+
+	rc = be64_to_cpu(msg.params[1]);
+	if (rc != OPAL_SUCCESS)
+		rc = -EIO;
+
+exit:
+	opal_async_release_token(token);
+	return rc;
+}
+
+static const struct rtc_class_ops opal_rtc_ops = {
+	.read_time	= opal_get_rtc_time,
+	.set_time	= opal_set_rtc_time,
+	.read_alarm	= opal_get_tpo_time,
+	.set_alarm	= opal_set_tpo_time,
+};
+
+static int opal_rtc_probe(struct platform_device *pdev)
+{
+	struct rtc_device *rtc;
+
+	if (pdev->dev.of_node && of_get_property(pdev->dev.of_node, "has-tpo",
+						 NULL))
+		device_set_wakeup_capable(&pdev->dev, true);
+
+	rtc = devm_rtc_device_register(&pdev->dev, DRVNAME, &opal_rtc_ops,
+				       THIS_MODULE);
+	if (IS_ERR(rtc))
+		return PTR_ERR(rtc);
+
+	rtc->uie_unsupported = 1;
+
+	return 0;
+}
+
+static const struct of_device_id opal_rtc_match[] = {
+	{
+		.compatible	= "ibm,opal-rtc",
+	},
+	{ }
+};
+MODULE_DEVICE_TABLE(of, opal_rtc_match);
+
+static const struct platform_device_id opal_rtc_driver_ids[] = {
+	{
+		.name		= "opal-rtc",
+	},
+	{ }
+};
+MODULE_DEVICE_TABLE(platform, opal_rtc_driver_ids);
+
+static struct platform_driver opal_rtc_driver = {
+	.probe		= opal_rtc_probe,
+	.id_table	= opal_rtc_driver_ids,
+	.driver		= {
+		.name		= DRVNAME,
+		.owner		= THIS_MODULE,
+		.of_match_table	= opal_rtc_match,
+	},
+};
+
+static int __init opal_rtc_init(void)
+{
+	if (!firmware_has_feature(FW_FEATURE_OPAL))
+		return -ENODEV;
+
+	return platform_driver_register(&opal_rtc_driver);
+}
+
+static void __exit opal_rtc_exit(void)
+{
+	platform_driver_unregister(&opal_rtc_driver);
+}
+
+MODULE_AUTHOR("Neelesh Gupta <neelegup@linux.vnet.ibm.com>");
+MODULE_DESCRIPTION("IBM OPAL RTC driver");
+MODULE_LICENSE("GPL");
+
+module_init(opal_rtc_init);
+module_exit(opal_rtc_exit);