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Subject[PATCH 5/6 v3] rtc: Add support for the RTC in VIA VT8500 and compatibles
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>
---
This implements the suggestions made by Lars. Reference to wakeup
was removed, as currently other code does not yet provide any
support for that.

It now also checks the status register for indication of a valid
time value before trying to read date/time registers.

Thanks,
Alexey

drivers/rtc/Kconfig | 7 +
drivers/rtc/Makefile | 1 +
drivers/rtc/rtc-vt8500.c | 365 ++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 373 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..e4f2aa9
--- /dev/null
+++ b/drivers/rtc/rtc-vt8500.c
@@ -0,0 +1,365 @@
+/*
+ * 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)
+
+#define VT8500_RTC_CR_ENABLE (1 << 0) /* Enable RTC */
+#define VT8500_RTC_CR_24H (1 << 1) /* 24h time format */
+#define VT8500_RTC_CR_SM_ENABLE (1 << 2) /* Enable periodic irqs */
+#define VT8500_RTC_CR_SM_SEC (1 << 3) /* 0: 1Hz/60, 1: 1Hz */
+#define VT8500_RTC_CR_CALIB (1 << 4) /* Enable calibration */
+
+struct vt8500_rtc {
+ void __iomem *regbase;
+ int irq_alarm;
+ int irq_hz;
+ struct rtc_device *rtc;
+ spinlock_t lock; /* Protects this structure */
+};
+
+static irqreturn_t vt8500_rtc_irq(int irq, void *dev_id)
+{
+ struct vt8500_rtc *vt8500_rtc = dev_id;
+ 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);
+
+ spin_unlock(&vt8500_rtc->lock);
+
+ 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);
+
+ return IRQ_HANDLED;
+}
+
+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;
+
+ if (!readl(vt8500_rtc->regbase + VT8500_RTC_ST)) {
+ dev_info(dev, "Clock not set!");
+ return -EINVAL;
+ }
+ 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 rtc_valid_tm(tm);
+}
+
+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 rtc_valid_tm(&alrm->time);
+}
+
+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_alarm_irq_enable(struct device *dev, unsigned int enabled)
+{
+ struct vt8500_rtc *vt8500_rtc = dev_get_drvdata(dev);
+ unsigned long tmp;
+
+ if (enabled) {
+ tmp = readl(vt8500_rtc->regbase + VT8500_RTC_AS);
+ writel(tmp | ALARM_ENABLE_MASK,
+ vt8500_rtc->regbase + VT8500_RTC_AS);
+ } else {
+ tmp = readl(vt8500_rtc->regbase + VT8500_RTC_AS);
+ writel(tmp & ~ALARM_ENABLE_MASK,
+ vt8500_rtc->regbase + VT8500_RTC_AS);
+ }
+ return 0;
+}
+
+static int vt8500_update_irq_enable(struct device *dev, unsigned int enabled)
+{
+ struct vt8500_rtc *vt8500_rtc = dev_get_drvdata(dev);
+ unsigned long tmp;
+
+ if (enabled) {
+ tmp = readl(vt8500_rtc->regbase + VT8500_RTC_CR);
+ writel(tmp | VT8500_RTC_CR_SM_SEC | VT8500_RTC_CR_SM_ENABLE,
+ vt8500_rtc->regbase + VT8500_RTC_CR);
+ } else {
+ tmp = readl(vt8500_rtc->regbase + VT8500_RTC_CR);
+ writel(tmp & ~VT8500_RTC_CR_SM_ENABLE,
+ vt8500_rtc->regbase + VT8500_RTC_CR);
+ }
+ return 0;
+}
+
+static const struct rtc_class_ops vt8500_rtc_ops = {
+ .read_time = vt8500_rtc_read_time,
+ .set_time = vt8500_rtc_set_time,
+ .read_alarm = vt8500_rtc_read_alarm,
+ .set_alarm = vt8500_rtc_set_alarm,
+ .alarm_irq_enable = vt8500_alarm_irq_enable,
+ .update_irq_enable = vt8500_update_irq_enable,
+};
+
+static int __devinit vt8500_rtc_probe(struct platform_device *pdev)
+{
+ 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);
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ if (!res) {
+ dev_err(&pdev->dev, "No I/O memory resource defined\n");
+ ret = -ENXIO;
+ goto err_free;
+ }
+
+ vt8500_rtc->irq_alarm = platform_get_irq(pdev, 0);
+ if (vt8500_rtc->irq_alarm < 0) {
+ dev_err(&pdev->dev, "No alarm IRQ resource defined\n");
+ ret = -ENXIO;
+ goto err_free;
+ }
+
+ vt8500_rtc->irq_hz = platform_get_irq(pdev, 1);
+ if (vt8500_rtc->irq_hz < 0) {
+ dev_err(&pdev->dev, "No 1Hz IRQ resource defined\n");
+ ret = -ENXIO;
+ goto err_free;
+ }
+
+ res = request_mem_region(res->start, resource_size(res), "vt8500-rtc");
+ if (res == NULL) {
+ dev_err(&pdev->dev, "failed to request I/O memory\n");
+ ret = -EBUSY;
+ goto err_free;
+ }
+
+ 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");
+ ret = -ENOMEM;
+ goto err_release;
+ }
+
+ /* Enable the second/minute interrupt generation and enable RTC */
+ writel(VT8500_RTC_CR_ENABLE | VT8500_RTC_CR_24H
+ | VT8500_RTC_CR_SM_ENABLE | VT8500_RTC_CR_SM_SEC,
+ 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(&pdev->dev,
+ "Failed to register RTC device -> %d\n", ret);
+ ret = -ENXIO;
+ goto err_unmap;
+ }
+
+ ret = request_irq(vt8500_rtc->irq_hz, vt8500_rtc_irq, 0,
+ "rtc 1Hz", vt8500_rtc);
+ if (ret < 0) {
+ dev_err(&pdev->dev, "can't get irq %i, err %d\n",
+ vt8500_rtc->irq_hz, ret);
+ goto err_unreg;
+ }
+
+ ret = request_irq(vt8500_rtc->irq_alarm, vt8500_rtc_irq, 0,
+ "rtc alarm", vt8500_rtc);
+ if (ret < 0) {
+ dev_err(&pdev->dev, "can't get irq %i, err %d\n",
+ vt8500_rtc->irq_alarm, ret);
+ goto err_free_hz;
+ }
+
+ return 0;
+
+err_free_hz:
+ free_irq(vt8500_rtc->irq_hz, vt8500_rtc);
+err_unreg:
+ rtc_device_unregister(vt8500_rtc->rtc);
+err_unmap:
+ iounmap(vt8500_rtc->regbase);
+err_release:
+ release_mem_region(res->start, resource_size(res));
+err_free:
+ kfree(vt8500_rtc);
+ return ret;
+}
+
+static int __devexit 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);
+ /* Disable alarm matching */
+ writel(0, vt8500_rtc->regbase + VT8500_RTC_IS);
+ iounmap(vt8500_rtc->regbase);
+ spin_unlock_irq(&vt8500_rtc->lock);
+
+ free_irq(vt8500_rtc->irq_alarm, vt8500_rtc);
+ free_irq(vt8500_rtc->irq_hz, vt8500_rtc);
+
+ kfree(vt8500_rtc);
+
+ return 0;
+}
+
+static struct platform_driver vt8500_rtc_driver = {
+ .probe = vt8500_rtc_probe,
+ .remove = __devexit_p(vt8500_rtc_remove),
+ .driver = {
+ .name = "vt8500-rtc",
+ .owner = THIS_MODULE,
+ },
+};
+
+static int __init vt8500_rtc_init(void)
+{
+ return platform_driver_register(&vt8500_rtc_driver);
+}
+module_init(vt8500_rtc_init);
+
+static void __exit vt8500_rtc_exit(void)
+{
+ platform_driver_unregister(&vt8500_rtc_driver);
+}
+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


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