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>
Cc: Lars-Peter Clausen <lars@metafoo.de>
Cc: Alexey Charkov <alchark@gmail.com>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

3 files changed, 374 insertions, 0 deletions

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index 8e437e2f6281..3db52f01d458 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -884,6 +884,13 @@ 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 612f5a88a8ee..986f17e51df8 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -99,6 +99,7 @@ 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 000000000000..b8bc862903ae
--- /dev/null
+++ b/drivers/rtc/rtc-vt8500.c
@@ -0,0 +1,366 @@
+/*
+ * 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;
+        struct resource         *res;
+        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;
+
+        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)
+                        + ((date >> DATE_CENTURY_S) & 1 ? 200 : 100);
+        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);
+
+        if (tm->tm_year < 100) {
+                dev_warn(dev, "Only years 2000-2199 are supported by the "
+                              "hardware!\n");
+                return -EINVAL;
+        }
+
+        writel((bin2bcd(tm->tm_year - 100) << 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 = readl(vt8500_rtc->regbase + VT8500_RTC_AS);
+
+        if (enabled)
+                tmp |= ALARM_ENABLE_MASK;
+        else
+                tmp &= ~ALARM_ENABLE_MASK;
+
+        writel(tmp, 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 = readl(vt8500_rtc->regbase + VT8500_RTC_CR);
+
+        if (enabled)
+                tmp |= VT8500_RTC_CR_SM_SEC | VT8500_RTC_CR_SM_ENABLE;
+        else
+                tmp &= ~VT8500_RTC_CR_SM_ENABLE;
+
+        writel(tmp, 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;
+        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);
+
+        vt8500_rtc->res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+        if (!vt8500_rtc->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;
+        }
+
+        vt8500_rtc->res = request_mem_region(vt8500_rtc->res->start,
+                                             resource_size(vt8500_rtc->res),
+                                             "vt8500-rtc");
+        if (vt8500_rtc->res == NULL) {
+                dev_err(&pdev->dev, "failed to request I/O memory\n");
+                ret = -EBUSY;
+                goto err_free;
+        }
+
+        vt8500_rtc->regbase = ioremap(vt8500_rtc->res->start,
+                                      resource_size(vt8500_rtc->res));
+        if (!vt8500_rtc->regbase) {
+                dev_err(&pdev->dev, "Unable to map RTC I/O memory\n");
+                ret = -EBUSY;
+                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);
+        if (IS_ERR(vt8500_rtc->rtc)) {
+                ret = PTR_ERR(vt8500_rtc->rtc);
+                dev_err(&pdev->dev,
+                        "Failed to register RTC device -> %d\n", ret);
+                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(vt8500_rtc->res->start,
+                           resource_size(vt8500_rtc->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);
+
+        free_irq(vt8500_rtc->irq_alarm, vt8500_rtc);
+        free_irq(vt8500_rtc->irq_hz, vt8500_rtc);
+
+        rtc_device_unregister(vt8500_rtc->rtc);
+
+        /* Disable alarm matching */
+        writel(0, vt8500_rtc->regbase + VT8500_RTC_IS);
+        iounmap(vt8500_rtc->regbase);
+        release_mem_region(vt8500_rtc->res->start,
+                           resource_size(vt8500_rtc->res));
+
+        kfree(vt8500_rtc);
+        platform_set_drvdata(pdev, NULL);
+
+        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");