rtc: add support for STK17TA8 chip

This patch adds support for the Simtek STK17TA8 timekeeping chip.

The STK17TA8 is quite similar to the DS1553, but differs in register layout
and in various control bits in the registers.  I chose to make this a new
driver to avoid confusion in the code and to not get lost in #ifdefs.

Signed-off-by: Thomas Hommel <thomas.hommel@gefanuc.com>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Cc: David Brownell <david-b@pacbell.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

3 files changed, 431 insertions, 0 deletions

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index 505f512ac254..9d8d40d5c8f7 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -308,6 +308,16 @@ config RTC_DRV_DS1553
           This driver can also be built as a module. If so, the module
           will be called rtc-ds1553.
 
+config RTC_DRV_STK17TA8
+        tristate "Simtek STK17TA8"
+        depends on RTC_CLASS
+        help
+          If you say yes here you get support for the
+          Simtek STK17TA8 timekeeping chip.
+
+          This driver can also be built as a module. If so, the module
+          will be called rtc-stk17ta8.
+
 config RTC_DRV_DS1742
         tristate "Dallas DS1742/1743"
         depends on RTC_CLASS
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index 3109af9a1651..7ede9e725360 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -32,6 +32,7 @@ obj-$(CONFIG_RTC_DRV_RS5C348)	+= rtc-rs5c348.o
 obj-$(CONFIG_RTC_DRV_M41T80)    += rtc-m41t80.o
 obj-$(CONFIG_RTC_DRV_M48T86)    += rtc-m48t86.o
 obj-$(CONFIG_RTC_DRV_DS1553)    += rtc-ds1553.o
+obj-$(CONFIG_RTC_DRV_STK17TA8)  += rtc-stk17ta8.o
 obj-$(CONFIG_RTC_DRV_RS5C313)   += rtc-rs5c313.o
 obj-$(CONFIG_RTC_DRV_EP93XX)    += rtc-ep93xx.o
 obj-$(CONFIG_RTC_DRV_SA1100)    += rtc-sa1100.o
diff --git a/drivers/rtc/rtc-stk17ta8.c b/drivers/rtc/rtc-stk17ta8.c
new file mode 100644
index 000000000000..f10d3facecbe
--- /dev/null
+++ b/drivers/rtc/rtc-stk17ta8.c
@@ -0,0 +1,420 @@
+/*
+ * A RTC driver for the Simtek STK17TA8
+ *
+ * By Thomas Hommel <thomas.hommel@gefanuc.com>
+ *
+ * Based on the DS1553 driver from
+ * Atsushi Nemoto <anemo@mba.ocn.ne.jp>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/bcd.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/delay.h>
+#include <linux/jiffies.h>
+#include <linux/interrupt.h>
+#include <linux/rtc.h>
+#include <linux/platform_device.h>
+#include <linux/io.h>
+
+#define DRV_VERSION "0.1"
+
+#define RTC_REG_SIZE            0x20000
+#define RTC_OFFSET              0x1fff0
+
+#define RTC_FLAGS               (RTC_OFFSET + 0)
+#define RTC_CENTURY             (RTC_OFFSET + 1)
+#define RTC_SECONDS_ALARM       (RTC_OFFSET + 2)
+#define RTC_MINUTES_ALARM       (RTC_OFFSET + 3)
+#define RTC_HOURS_ALARM         (RTC_OFFSET + 4)
+#define RTC_DATE_ALARM          (RTC_OFFSET + 5)
+#define RTC_INTERRUPTS          (RTC_OFFSET + 6)
+#define RTC_WATCHDOG            (RTC_OFFSET + 7)
+#define RTC_CALIBRATION         (RTC_OFFSET + 8)
+#define RTC_SECONDS             (RTC_OFFSET + 9)
+#define RTC_MINUTES             (RTC_OFFSET + 10)
+#define RTC_HOURS               (RTC_OFFSET + 11)
+#define RTC_DAY                 (RTC_OFFSET + 12)
+#define RTC_DATE                (RTC_OFFSET + 13)
+#define RTC_MONTH               (RTC_OFFSET + 14)
+#define RTC_YEAR                (RTC_OFFSET + 15)
+
+#define RTC_SECONDS_MASK        0x7f
+#define RTC_DAY_MASK            0x07
+#define RTC_CAL_MASK            0x3f
+
+/* Bits in the Calibration register */
+#define RTC_STOP                0x80
+
+/* Bits in the Flags register */
+#define RTC_FLAGS_AF            0x40
+#define RTC_FLAGS_PF            0x20
+#define RTC_WRITE               0x02
+#define RTC_READ                0x01
+
+/* Bits in the Interrupts register */
+#define RTC_INTS_AIE            0x40
+
+struct rtc_plat_data {
+        struct rtc_device *rtc;
+        void __iomem *ioaddr;
+        unsigned long baseaddr;
+        unsigned long last_jiffies;
+        int irq;
+        unsigned int irqen;
+        int alrm_sec;
+        int alrm_min;
+        int alrm_hour;
+        int alrm_mday;
+};
+
+static int stk17ta8_rtc_set_time(struct device *dev, struct rtc_time *tm)
+{
+        struct platform_device *pdev = to_platform_device(dev);
+        struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
+        void __iomem *ioaddr = pdata->ioaddr;
+        u8 flags;
+
+        flags = readb(pdata->ioaddr + RTC_FLAGS);
+        writeb(flags | RTC_WRITE, pdata->ioaddr + RTC_FLAGS);
+
+        writeb(BIN2BCD(tm->tm_year % 100), ioaddr + RTC_YEAR);
+        writeb(BIN2BCD(tm->tm_mon + 1), ioaddr + RTC_MONTH);
+        writeb(BIN2BCD(tm->tm_wday) & RTC_DAY_MASK, ioaddr + RTC_DAY);
+        writeb(BIN2BCD(tm->tm_mday), ioaddr + RTC_DATE);
+        writeb(BIN2BCD(tm->tm_hour), ioaddr + RTC_HOURS);
+        writeb(BIN2BCD(tm->tm_min), ioaddr + RTC_MINUTES);
+        writeb(BIN2BCD(tm->tm_sec) & RTC_SECONDS_MASK, ioaddr + RTC_SECONDS);
+        writeb(BIN2BCD((tm->tm_year + 1900) / 100), ioaddr + RTC_CENTURY);
+
+        writeb(flags & ~RTC_WRITE, pdata->ioaddr + RTC_FLAGS);
+        return 0;
+}
+
+static int stk17ta8_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+        struct platform_device *pdev = to_platform_device(dev);
+        struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
+        void __iomem *ioaddr = pdata->ioaddr;
+        unsigned int year, month, day, hour, minute, second, week;
+        unsigned int century;
+        u8 flags;
+
+        /* give enough time to update RTC in case of continuous read */
+        if (pdata->last_jiffies == jiffies)
+                msleep(1);
+        pdata->last_jiffies = jiffies;
+
+        flags = readb(pdata->ioaddr + RTC_FLAGS);
+        writeb(flags | RTC_READ, ioaddr + RTC_FLAGS);
+        second = readb(ioaddr + RTC_SECONDS) & RTC_SECONDS_MASK;
+        minute = readb(ioaddr + RTC_MINUTES);
+        hour = readb(ioaddr + RTC_HOURS);
+        day = readb(ioaddr + RTC_DATE);
+        week = readb(ioaddr + RTC_DAY) & RTC_DAY_MASK;
+        month = readb(ioaddr + RTC_MONTH);
+        year = readb(ioaddr + RTC_YEAR);
+        century = readb(ioaddr + RTC_CENTURY);
+        writeb(flags & ~RTC_READ, ioaddr + RTC_FLAGS);
+        tm->tm_sec = BCD2BIN(second);
+        tm->tm_min = BCD2BIN(minute);
+        tm->tm_hour = BCD2BIN(hour);
+        tm->tm_mday = BCD2BIN(day);
+        tm->tm_wday = BCD2BIN(week);
+        tm->tm_mon = BCD2BIN(month) - 1;
+        /* year is 1900 + tm->tm_year */
+        tm->tm_year = BCD2BIN(year) + BCD2BIN(century) * 100 - 1900;
+
+        if (rtc_valid_tm(tm) < 0) {
+                dev_err(dev, "retrieved date/time is not valid.\n");
+                rtc_time_to_tm(0, tm);
+        }
+        return 0;
+}
+
+static void stk17ta8_rtc_update_alarm(struct rtc_plat_data *pdata)
+{
+        void __iomem *ioaddr = pdata->ioaddr;
+        unsigned long irqflags;
+        u8 flags;
+
+        spin_lock_irqsave(&pdata->rtc->irq_lock, irqflags);
+
+        flags = readb(ioaddr + RTC_FLAGS);
+        writeb(flags | RTC_WRITE, ioaddr + RTC_FLAGS);
+
+        writeb(pdata->alrm_mday < 0 || (pdata->irqen & RTC_UF) ?
+               0x80 : BIN2BCD(pdata->alrm_mday),
+               ioaddr + RTC_DATE_ALARM);
+        writeb(pdata->alrm_hour < 0 || (pdata->irqen & RTC_UF) ?
+               0x80 : BIN2BCD(pdata->alrm_hour),
+               ioaddr + RTC_HOURS_ALARM);
+        writeb(pdata->alrm_min < 0 || (pdata->irqen & RTC_UF) ?
+               0x80 : BIN2BCD(pdata->alrm_min),
+               ioaddr + RTC_MINUTES_ALARM);
+        writeb(pdata->alrm_sec < 0 || (pdata->irqen & RTC_UF) ?
+               0x80 : BIN2BCD(pdata->alrm_sec),
+               ioaddr + RTC_SECONDS_ALARM);
+        writeb(pdata->irqen ? RTC_INTS_AIE : 0, ioaddr + RTC_INTERRUPTS);
+        readb(ioaddr + RTC_FLAGS);      /* clear interrupts */
+        writeb(flags & ~RTC_WRITE, ioaddr + RTC_FLAGS);
+        spin_unlock_irqrestore(&pdata->rtc->irq_lock, irqflags);
+}
+
+static int stk17ta8_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
+{
+        struct platform_device *pdev = to_platform_device(dev);
+        struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
+
+        if (pdata->irq < 0)
+                return -EINVAL;
+        pdata->alrm_mday = alrm->time.tm_mday;
+        pdata->alrm_hour = alrm->time.tm_hour;
+        pdata->alrm_min = alrm->time.tm_min;
+        pdata->alrm_sec = alrm->time.tm_sec;
+        if (alrm->enabled)
+                pdata->irqen |= RTC_AF;
+        stk17ta8_rtc_update_alarm(pdata);
+        return 0;
+}
+
+static int stk17ta8_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
+{
+        struct platform_device *pdev = to_platform_device(dev);
+        struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
+
+        if (pdata->irq < 0)
+                return -EINVAL;
+        alrm->time.tm_mday = pdata->alrm_mday < 0 ? 0 : pdata->alrm_mday;
+        alrm->time.tm_hour = pdata->alrm_hour < 0 ? 0 : pdata->alrm_hour;
+        alrm->time.tm_min = pdata->alrm_min < 0 ? 0 : pdata->alrm_min;
+        alrm->time.tm_sec = pdata->alrm_sec < 0 ? 0 : pdata->alrm_sec;
+        alrm->enabled = (pdata->irqen & RTC_AF) ? 1 : 0;
+        return 0;
+}
+
+static irqreturn_t stk17ta8_rtc_interrupt(int irq, void *dev_id)
+{
+        struct platform_device *pdev = dev_id;
+        struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
+        void __iomem *ioaddr = pdata->ioaddr;
+        unsigned long events = RTC_IRQF;
+
+        /* read and clear interrupt */
+        if (!(readb(ioaddr + RTC_FLAGS) & RTC_FLAGS_AF))
+                return IRQ_NONE;
+        if (readb(ioaddr + RTC_SECONDS_ALARM) & 0x80)
+                events |= RTC_UF;
+        else
+                events |= RTC_AF;
+        rtc_update_irq(pdata->rtc, 1, events);
+        return IRQ_HANDLED;
+}
+
+static void stk17ta8_rtc_release(struct device *dev)
+{
+        struct platform_device *pdev = to_platform_device(dev);
+        struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
+
+        if (pdata->irq >= 0) {
+                pdata->irqen = 0;
+                stk17ta8_rtc_update_alarm(pdata);
+        }
+}
+
+static int stk17ta8_rtc_ioctl(struct device *dev, unsigned int cmd,
+                            unsigned long arg)
+{
+        struct platform_device *pdev = to_platform_device(dev);
+        struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
+
+        if (pdata->irq < 0)
+                return -ENOIOCTLCMD; /* fall back into rtc-dev's emulation */
+        switch (cmd) {
+        case RTC_AIE_OFF:
+                pdata->irqen &= ~RTC_AF;
+                stk17ta8_rtc_update_alarm(pdata);
+                break;
+        case RTC_AIE_ON:
+                pdata->irqen |= RTC_AF;
+                stk17ta8_rtc_update_alarm(pdata);
+                break;
+        default:
+                return -ENOIOCTLCMD;
+        }
+        return 0;
+}
+
+static const struct rtc_class_ops stk17ta8_rtc_ops = {
+        .read_time      = stk17ta8_rtc_read_time,
+        .set_time       = stk17ta8_rtc_set_time,
+        .read_alarm     = stk17ta8_rtc_read_alarm,
+        .set_alarm      = stk17ta8_rtc_set_alarm,
+        .release        = stk17ta8_rtc_release,
+        .ioctl          = stk17ta8_rtc_ioctl,
+};
+
+static ssize_t stk17ta8_nvram_read(struct kobject *kobj, char *buf,
+                                 loff_t pos, size_t size)
+{
+        struct platform_device *pdev =
+                to_platform_device(container_of(kobj, struct device, kobj));
+        struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
+        void __iomem *ioaddr = pdata->ioaddr;
+        ssize_t count;
+
+        for (count = 0; size > 0 && pos < RTC_OFFSET; count++, size--)
+                *buf++ = readb(ioaddr + pos++);
+        return count;
+}
+
+static ssize_t stk17ta8_nvram_write(struct kobject *kobj, char *buf,
+                                  loff_t pos, size_t size)
+{
+        struct platform_device *pdev =
+                to_platform_device(container_of(kobj, struct device, kobj));
+        struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
+        void __iomem *ioaddr = pdata->ioaddr;
+        ssize_t count;
+
+        for (count = 0; size > 0 && pos < RTC_OFFSET; count++, size--)
+                writeb(*buf++, ioaddr + pos++);
+        return count;
+}
+
+static struct bin_attribute stk17ta8_nvram_attr = {
+        .attr = {
+                .name = "nvram",
+                .mode = S_IRUGO | S_IWUGO,
+                .owner = THIS_MODULE,
+        },
+        .size = RTC_OFFSET,
+        .read = stk17ta8_nvram_read,
+        .write = stk17ta8_nvram_write,
+};
+
+static int __init stk17ta8_rtc_probe(struct platform_device *pdev)
+{
+        struct rtc_device *rtc;
+        struct resource *res;
+        unsigned int cal;
+        unsigned int flags;
+        struct rtc_plat_data *pdata;
+        void __iomem *ioaddr = NULL;
+        int ret = 0;
+
+        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+        if (!res)
+                return -ENODEV;
+
+        pdata = kzalloc(sizeof(*pdata), GFP_KERNEL);
+        if (!pdata)
+                return -ENOMEM;
+        pdata->irq = -1;
+        if (!request_mem_region(res->start, RTC_REG_SIZE, pdev->name)) {
+                ret = -EBUSY;
+                goto out;
+        }
+        pdata->baseaddr = res->start;
+        ioaddr = ioremap(pdata->baseaddr, RTC_REG_SIZE);
+        if (!ioaddr) {
+                ret = -ENOMEM;
+                goto out;
+        }
+        pdata->ioaddr = ioaddr;
+        pdata->irq = platform_get_irq(pdev, 0);
+
+        /* turn RTC on if it was not on */
+        cal = readb(ioaddr + RTC_CALIBRATION);
+        if (cal & RTC_STOP) {
+                cal &= RTC_CAL_MASK;
+                flags = readb(ioaddr + RTC_FLAGS);
+                writeb(flags | RTC_WRITE, ioaddr + RTC_FLAGS);
+                writeb(cal, ioaddr + RTC_CALIBRATION);
+                writeb(flags & ~RTC_WRITE, ioaddr + RTC_FLAGS);
+        }
+        if (readb(ioaddr + RTC_FLAGS) & RTC_FLAGS_PF)
+                dev_warn(&pdev->dev, "voltage-low detected.\n");
+
+        if (pdata->irq >= 0) {
+                writeb(0, ioaddr + RTC_INTERRUPTS);
+                if (request_irq(pdata->irq, stk17ta8_rtc_interrupt,
+                                IRQF_DISABLED | IRQF_SHARED,
+                                pdev->name, pdev) < 0) {
+                        dev_warn(&pdev->dev, "interrupt not available.\n");
+                        pdata->irq = -1;
+                }
+        }
+
+        rtc = rtc_device_register(pdev->name, &pdev->dev,
+                                  &stk17ta8_rtc_ops, THIS_MODULE);
+        if (IS_ERR(rtc)) {
+                ret = PTR_ERR(rtc);
+                goto out;
+        }
+        pdata->rtc = rtc;
+        pdata->last_jiffies = jiffies;
+        platform_set_drvdata(pdev, pdata);
+        ret = sysfs_create_bin_file(&pdev->dev.kobj, &stk17ta8_nvram_attr);
+        if (ret)
+                goto out;
+        return 0;
+ out:
+        if (pdata->rtc)
+                rtc_device_unregister(pdata->rtc);
+        if (pdata->irq >= 0)
+                free_irq(pdata->irq, pdev);
+        if (ioaddr)
+                iounmap(ioaddr);
+        if (pdata->baseaddr)
+                release_mem_region(pdata->baseaddr, RTC_REG_SIZE);
+        kfree(pdata);
+        return ret;
+}
+
+static int __devexit stk17ta8_rtc_remove(struct platform_device *pdev)
+{
+        struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
+
+        sysfs_remove_bin_file(&pdev->dev.kobj, &stk17ta8_nvram_attr);
+        rtc_device_unregister(pdata->rtc);
+        if (pdata->irq >= 0) {
+                writeb(0, pdata->ioaddr + RTC_INTERRUPTS);
+                free_irq(pdata->irq, pdev);
+        }
+        iounmap(pdata->ioaddr);
+        release_mem_region(pdata->baseaddr, RTC_REG_SIZE);
+        kfree(pdata);
+        return 0;
+}
+
+static struct platform_driver stk17ta8_rtc_driver = {
+        .probe          = stk17ta8_rtc_probe,
+        .remove         = __devexit_p(stk17ta8_rtc_remove),
+        .driver         = {
+                .name   = "stk17ta8",
+                .owner  = THIS_MODULE,
+        },
+};
+
+static __init int stk17ta8_init(void)
+{
+        return platform_driver_register(&stk17ta8_rtc_driver);
+}
+
+static __exit void stk17ta8_exit(void)
+{
+        return platform_driver_unregister(&stk17ta8_rtc_driver);
+}
+
+module_init(stk17ta8_init);
+module_exit(stk17ta8_exit);
+
+MODULE_AUTHOR("Thomas Hommel <thomas.hommel@gefanuc.com>");
+MODULE_DESCRIPTION("Simtek STK17TA8 RTC driver");
+MODULE_LICENSE("GPL");
+MODULE_VERSION(DRV_VERSION);