[PATCH 5/6 v2] rtc: Add support for the RTC in VIA VT8500 and compatibles

[Alexey Charkov <alchark@gmail.com>]

This adds a driver for the RTC devices in VIA and WonderMedia
Systems-on-Chip. Alarm, 1Hz interrupts, reading and setting time
are supported.

Signed-off-by: Alexey Charkov <alchark@gmail.com>
---

Please review and (if appropriate) commit to a relevant git tree for
further integration in 2.6.38.

Compared to the previous submission, this code just contains a rebase
against the latest changes introduced in 2.6.37 merge window.

Relevant platform definitions are introduced by PATCH 1/6 in this series,
so one would need that to make use of this code.

Due credits go to the community for providing feedback, advice and
testing.

 drivers/rtc/Kconfig      |    7 +
 drivers/rtc/Makefile     |    1 +
 drivers/rtc/rtc-vt8500.c |  363 ++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 371 insertions(+), 0 deletions(-)
 create mode 100644 drivers/rtc/rtc-vt8500.c

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index 2883428..27ed129 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -865,6 +865,13 @@ config RTC_DRV_PXA
          This RTC driver uses PXA RTC registers available since pxa27x
          series (RDxR, RYxR) instead of legacy RCNR, RTAR.
 
+config RTC_DRV_VT8500
+	tristate "VIA/WonderMedia 85xx SoC RTC"
+	depends on ARCH_VT8500
+	help
+	  If you say Y here you will get access to the real time clock
+	  built into your VIA VT8500 SoC or its relatives.
+
 
 config RTC_DRV_SUN4V
 	bool "SUN4V Hypervisor RTC"
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index 4c2832d..1a354e1 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -97,6 +97,7 @@ obj-$(CONFIG_RTC_DRV_TWL4030)	+= rtc-twl.o
 obj-$(CONFIG_RTC_DRV_TX4939)	+= rtc-tx4939.o
 obj-$(CONFIG_RTC_DRV_V3020)	+= rtc-v3020.o
 obj-$(CONFIG_RTC_DRV_VR41XX)	+= rtc-vr41xx.o
+obj-$(CONFIG_RTC_DRV_VT8500)	+= rtc-vt8500.o
 obj-$(CONFIG_RTC_DRV_WM831X)	+= rtc-wm831x.o
 obj-$(CONFIG_RTC_DRV_WM8350)	+= rtc-wm8350.o
 obj-$(CONFIG_RTC_DRV_X1205)	+= rtc-x1205.o
diff --git a/drivers/rtc/rtc-vt8500.c b/drivers/rtc/rtc-vt8500.c
new file mode 100644
index 0000000..7260c95
--- /dev/null
+++ b/drivers/rtc/rtc-vt8500.c
@@ -0,0 +1,363 @@
+/*
+ * drivers/rtc/rtc-vt8500.c
+ *
+ *  Copyright (C) 2010 Alexey Charkov <alchark@gmail.com>
+ *
+ * Based on rtc-pxa.c
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * 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.
+ */
+
+#include <linux/module.h>
+#include <linux/rtc.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/bcd.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+
+/*
+ * Register definitions
+ */
+#define VT8500_RTC_TS		0x00	/* Time set */
+#define VT8500_RTC_DS		0x04	/* Date set */
+#define VT8500_RTC_AS		0x08	/* Alarm set */
+#define VT8500_RTC_CR		0x0c	/* Control */
+#define VT8500_RTC_TR		0x10	/* Time read */
+#define VT8500_RTC_DR		0x14	/* Date read */
+#define VT8500_RTC_WS		0x18	/* Write status */
+#define VT8500_RTC_CL		0x20	/* Calibration */
+#define VT8500_RTC_IS		0x24	/* Interrupt status */
+#define VT8500_RTC_ST		0x28	/* Status */
+
+#define INVALID_TIME_BIT	(1 << 31)
+
+#define DATE_CENTURY_S		19
+#define DATE_YEAR_S		11
+#define DATE_YEAR_MASK		(0xff << DATE_YEAR_S)
+#define DATE_MONTH_S		6
+#define DATE_MONTH_MASK		(0x1f << DATE_MONTH_S)
+#define DATE_DAY_MASK		0x3f
+
+#define TIME_DOW_S		20
+#define TIME_DOW_MASK		(0x07 << TIME_DOW_S)
+#define TIME_HOUR_S		14
+#define TIME_HOUR_MASK		(0x3f << TIME_HOUR_S)
+#define TIME_MIN_S		7
+#define TIME_MIN_MASK		(0x7f << TIME_MIN_S)
+#define TIME_SEC_MASK		0x7f
+
+#define ALARM_DAY_S		20
+#define ALARM_DAY_MASK		(0x3f << ALARM_DAY_S)
+
+#define ALARM_DAY_BIT		(1 << 29)
+#define ALARM_HOUR_BIT		(1 << 28)
+#define ALARM_MIN_BIT		(1 << 27)
+#define ALARM_SEC_BIT		(1 << 26)
+
+#define ALARM_ENABLE_MASK	(ALARM_DAY_BIT \
+				| ALARM_HOUR_BIT \
+				| ALARM_MIN_BIT \
+				| ALARM_SEC_BIT)
+
+struct vt8500_rtc {
+	void __iomem		*regbase;
+	int			irq_alarm;
+	int			irq_hz;
+	struct rtc_device	*rtc;
+	spinlock_t		lock;		/* Protects this structure */
+	struct rtc_time		rtc_alarm;
+};
+
+static irqreturn_t vt8500_rtc_irq(int irq, void *dev_id)
+{
+	struct platform_device *pdev = to_platform_device(dev_id);
+	struct vt8500_rtc *vt8500_rtc = platform_get_drvdata(pdev);
+	u32 isr;
+	unsigned long events = 0;
+
+	spin_lock(&vt8500_rtc->lock);
+
+	/* clear interrupt sources */
+	isr = readl(vt8500_rtc->regbase + VT8500_RTC_IS);
+	writel(isr, vt8500_rtc->regbase + VT8500_RTC_IS);
+
+	if (isr & 1)
+		events |= RTC_AF | RTC_IRQF;
+
+	/* Only second/minute interrupts are supported */
+	if (isr & 2)
+		events |= RTC_UF | RTC_IRQF;
+
+	rtc_update_irq(vt8500_rtc->rtc, 1, events);
+
+	spin_unlock(&vt8500_rtc->lock);
+	return IRQ_HANDLED;
+}
+
+static int vt8500_rtc_open(struct device *dev)
+{
+	struct vt8500_rtc *vt8500_rtc = dev_get_drvdata(dev);
+	int ret;
+
+	ret = request_irq(vt8500_rtc->irq_hz, vt8500_rtc_irq, IRQF_DISABLED,
+			  "rtc 1Hz", dev);
+	if (ret < 0) {
+		dev_err(dev, "can't get irq %i, err %d\n", vt8500_rtc->irq_hz,
+			ret);
+		goto err_irq_hz;
+	}
+	ret = request_irq(vt8500_rtc->irq_alarm, vt8500_rtc_irq, IRQF_DISABLED,
+			  "rtc alarm", dev);
+	if (ret < 0) {
+		dev_err(dev, "can't get irq %i, err %d\n",
+			vt8500_rtc->irq_alarm, ret);
+		goto err_irq_alarm;
+	}
+	return 0;
+
+err_irq_alarm:
+	free_irq(vt8500_rtc->irq_hz, dev);
+err_irq_hz:
+	return ret;
+}
+
+static void vt8500_rtc_release(struct device *dev)
+{
+	struct vt8500_rtc *vt8500_rtc = dev_get_drvdata(dev);
+
+	spin_lock_irq(&vt8500_rtc->lock);
+	/* Disable alarm matching */
+	writel(0, vt8500_rtc->regbase + VT8500_RTC_IS);
+	spin_unlock_irq(&vt8500_rtc->lock);
+
+	free_irq(vt8500_rtc->irq_alarm, dev);
+	free_irq(vt8500_rtc->irq_hz, dev);
+}
+
+static int vt8500_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+	struct vt8500_rtc *vt8500_rtc = dev_get_drvdata(dev);
+	u32 date, time;
+
+	date = readl(vt8500_rtc->regbase + VT8500_RTC_DR);
+	time = readl(vt8500_rtc->regbase + VT8500_RTC_TR);
+
+	tm->tm_sec = bcd2bin(time & TIME_SEC_MASK);
+	tm->tm_min = bcd2bin((time & TIME_MIN_MASK) >> TIME_MIN_S);
+	tm->tm_hour = bcd2bin((time & TIME_HOUR_MASK) >> TIME_HOUR_S);
+	tm->tm_mday = bcd2bin(date & DATE_DAY_MASK);
+	tm->tm_mon = bcd2bin((date & DATE_MONTH_MASK) >> DATE_MONTH_S);
+	tm->tm_year = bcd2bin((date & DATE_YEAR_MASK) >> DATE_YEAR_S);
+	tm->tm_wday = (time & TIME_DOW_MASK) >> TIME_DOW_S;
+
+	return 0;
+}
+
+static int vt8500_rtc_set_time(struct device *dev, struct rtc_time *tm)
+{
+	struct vt8500_rtc *vt8500_rtc = dev_get_drvdata(dev);
+
+	writel((bin2bcd(tm->tm_year) << DATE_YEAR_S)
+		| (bin2bcd(tm->tm_mon) << DATE_MONTH_S)
+		| (bin2bcd(tm->tm_mday)),
+		vt8500_rtc->regbase + VT8500_RTC_DS);
+	writel((bin2bcd(tm->tm_wday) << TIME_DOW_S)
+		| (bin2bcd(tm->tm_hour) << TIME_HOUR_S)
+		| (bin2bcd(tm->tm_min) << TIME_MIN_S)
+		| (bin2bcd(tm->tm_sec)),
+		vt8500_rtc->regbase + VT8500_RTC_TS);
+
+	return 0;
+}
+
+static int vt8500_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
+{
+	struct vt8500_rtc *vt8500_rtc = dev_get_drvdata(dev);
+	u32 isr, alarm;
+
+	alarm = readl(vt8500_rtc->regbase + VT8500_RTC_AS);
+	isr = readl(vt8500_rtc->regbase + VT8500_RTC_IS);
+
+	alrm->time.tm_mday = bcd2bin((alarm & ALARM_DAY_MASK) >> ALARM_DAY_S);
+	alrm->time.tm_hour = bcd2bin((alarm & TIME_HOUR_MASK) >> TIME_HOUR_S);
+	alrm->time.tm_min = bcd2bin((alarm & TIME_MIN_MASK) >> TIME_MIN_S);
+	alrm->time.tm_sec = bcd2bin((alarm & TIME_SEC_MASK));
+
+	alrm->enabled = (alarm & ALARM_ENABLE_MASK) ? 1 : 0;
+
+	alrm->pending = (isr & 1) ? 1 : 0;
+	return 0;
+}
+
+static int vt8500_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
+{
+	struct vt8500_rtc *vt8500_rtc = dev_get_drvdata(dev);
+
+	writel((alrm->enabled ? ALARM_ENABLE_MASK : 0)
+		| (bin2bcd(alrm->time.tm_mday) << ALARM_DAY_S)
+		| (bin2bcd(alrm->time.tm_hour) << TIME_HOUR_S)
+		| (bin2bcd(alrm->time.tm_min) << TIME_MIN_S)
+		| (bin2bcd(alrm->time.tm_sec)),
+		vt8500_rtc->regbase + VT8500_RTC_AS);
+
+	return 0;
+}
+
+static int vt8500_rtc_ioctl(struct device *dev, unsigned int cmd,
+		unsigned long arg)
+{
+	struct vt8500_rtc *vt8500_rtc = dev_get_drvdata(dev);
+	int ret = 0;
+	unsigned long tmp;
+
+	spin_lock_irq(&vt8500_rtc->lock);
+	switch (cmd) {
+	case RTC_AIE_OFF:
+		tmp = readl(vt8500_rtc->regbase + VT8500_RTC_AS);
+		writel(tmp & ~ALARM_ENABLE_MASK,
+		       vt8500_rtc->regbase + VT8500_RTC_AS);
+		break;
+	case RTC_AIE_ON:
+		tmp = readl(vt8500_rtc->regbase + VT8500_RTC_AS);
+		writel(tmp | ALARM_ENABLE_MASK,
+		       vt8500_rtc->regbase + VT8500_RTC_AS);
+		break;
+	case RTC_UIE_OFF:
+		tmp = readl(vt8500_rtc->regbase + VT8500_RTC_CR);
+		writel(tmp & ~(1 << 2),
+		       vt8500_rtc->regbase + VT8500_RTC_CR);
+		break;
+	case RTC_UIE_ON:
+		tmp = readl(vt8500_rtc->regbase + VT8500_RTC_CR);
+		writel(tmp | ((1 << 3) | (1 << 2)),
+		       vt8500_rtc->regbase + VT8500_RTC_CR);
+		break;
+	default:
+		ret = -ENOIOCTLCMD;
+	}
+
+	spin_unlock_irq(&vt8500_rtc->lock);
+	return ret;
+}
+
+static const struct rtc_class_ops vt8500_rtc_ops = {
+	.open = vt8500_rtc_open,
+	.release = vt8500_rtc_release,
+	.ioctl = vt8500_rtc_ioctl,
+	.read_time = vt8500_rtc_read_time,
+	.set_time = vt8500_rtc_set_time,
+	.read_alarm = vt8500_rtc_read_alarm,
+	.set_alarm = vt8500_rtc_set_alarm,
+};
+
+static int __init vt8500_rtc_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct vt8500_rtc *vt8500_rtc;
+	struct resource *res;
+	int ret;
+
+	vt8500_rtc = kzalloc(sizeof(struct vt8500_rtc), GFP_KERNEL);
+	if (!vt8500_rtc)
+		return -ENOMEM;
+
+	spin_lock_init(&vt8500_rtc->lock);
+	platform_set_drvdata(pdev, vt8500_rtc);
+
+	ret = -ENXIO;
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res) {
+		dev_err(dev, "No I/O memory resource defined\n");
+		goto err_map;
+	}
+
+	vt8500_rtc->irq_alarm = platform_get_irq(pdev, 0);
+	if (vt8500_rtc->irq_alarm < 0) {
+		dev_err(dev, "No alarm IRQ resource defined\n");
+		goto err_map;
+	}
+
+	vt8500_rtc->irq_hz = platform_get_irq(pdev, 1);
+	if (vt8500_rtc->irq_hz < 0) {
+		dev_err(dev, "No 1Hz IRQ resource defined\n");
+		goto err_map;
+	}
+
+	ret = -ENOMEM;
+	vt8500_rtc->regbase = ioremap(res->start, resource_size(res));
+	if (!vt8500_rtc->regbase) {
+		dev_err(&pdev->dev, "Unable to map RTC I/O memory\n");
+		goto err_map;
+	}
+
+	/* Enable the second/minute interrupt generation and enable RTC */
+	writel((1 << 3) | (1 << 2) | 1, vt8500_rtc->regbase + VT8500_RTC_CR);
+
+	vt8500_rtc->rtc = rtc_device_register("vt8500-rtc", &pdev->dev,
+					      &vt8500_rtc_ops, THIS_MODULE);
+	ret = PTR_ERR(vt8500_rtc->rtc);
+	if (IS_ERR(vt8500_rtc->rtc)) {
+		dev_err(dev, "Failed to register RTC device -> %d\n", ret);
+		goto err_rtc_reg;
+	}
+
+	device_init_wakeup(dev, 1);
+
+	return 0;
+
+err_rtc_reg:
+	iounmap(vt8500_rtc->regbase);
+err_map:
+	kfree(vt8500_rtc);
+	return ret;
+}
+
+static int __exit vt8500_rtc_remove(struct platform_device *pdev)
+{
+	struct vt8500_rtc *vt8500_rtc = platform_get_drvdata(pdev);
+
+	rtc_device_unregister(vt8500_rtc->rtc);
+
+	spin_lock_irq(&vt8500_rtc->lock);
+	iounmap(vt8500_rtc->regbase);
+	spin_unlock_irq(&vt8500_rtc->lock);
+
+	kfree(vt8500_rtc);
+
+	return 0;
+}
+
+static struct platform_driver vt8500_rtc_driver = {
+	.probe		= vt8500_rtc_probe,
+	.remove		= __exit_p(vt8500_rtc_remove),
+	.driver		= {
+		.name	= "vt8500-rtc"
+	},
+};
+
+static int __init vt8500_rtc_init(void)
+{
+	return platform_driver_register(&vt8500_rtc_driver);
+}
+
+static void __exit vt8500_rtc_exit(void)
+{
+	platform_driver_unregister(&vt8500_rtc_driver);
+}
+
+module_init(vt8500_rtc_init);
+module_exit(vt8500_rtc_exit);
+
+MODULE_AUTHOR("Alexey Charkov <alchark@gmail.com>");
+MODULE_DESCRIPTION("VIA VT8500 SoC Realtime Clock Driver (RTC)");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:vt8500-rtc");
-- 
1.7.3.2