rtc: snvs: add Freescale rtc-snvs driver

Add an RTC driver for Freescale Secure Non-Volatile Storage (SNVS)
Low Power (LP) RTC.

Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
Reviewed-by: Stephen Boyd <sboyd@codeaurora.org>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Cc: Kim Phillips <kim.phillips@freescale.com>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

3 files changed, 362 insertions, 0 deletions

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index d4681c97f7cc..f87bfea6718c 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -1109,4 +1109,15 @@ config RTC_DRV_MXC
            This driver can also be built as a module, if so, the module
            will be called "rtc-mxc".
 
+config RTC_DRV_SNVS
+        tristate "Freescale SNVS RTC support"
+        depends on HAS_IOMEM
+        depends on OF
+        help
+           If you say yes here you get support for the Freescale SNVS
+           Low Power (LP) RTC module.
+
+           This driver can also be built as a module, if so, the module
+           will be called "rtc-snvs".
+
 endif # RTC_CLASS
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index 7ecdb2983dde..6056f71033db 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -97,6 +97,7 @@ obj-$(CONFIG_RTC_DRV_S35390A)	+= rtc-s35390a.o
 obj-$(CONFIG_RTC_DRV_S3C)       += rtc-s3c.o
 obj-$(CONFIG_RTC_DRV_SA1100)    += rtc-sa1100.o
 obj-$(CONFIG_RTC_DRV_SH)        += rtc-sh.o
+obj-$(CONFIG_RTC_DRV_SNVS)      += rtc-snvs.o
 obj-$(CONFIG_RTC_DRV_SPEAR)     += rtc-spear.o
 obj-$(CONFIG_RTC_DRV_STARFIRE)  += rtc-starfire.o
 obj-$(CONFIG_RTC_DRV_STK17TA8)  += rtc-stk17ta8.o
diff --git a/drivers/rtc/rtc-snvs.c b/drivers/rtc/rtc-snvs.c
new file mode 100644
index 000000000000..3c0da333f465
--- /dev/null
+++ b/drivers/rtc/rtc-snvs.c
@@ -0,0 +1,350 @@
+/*
+ * Copyright (C) 2011-2012 Freescale Semiconductor, Inc.
+ *
+ * The code contained herein is licensed under the GNU General Public
+ * License. You may obtain a copy of the GNU General Public License
+ * Version 2 or later at the following locations:
+ *
+ * http://www.opensource.org/licenses/gpl-license.html
+ * http://www.gnu.org/copyleft/gpl.html
+ */
+
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/rtc.h>
+
+/* These register offsets are relative to LP (Low Power) range */
+#define SNVS_LPCR               0x04
+#define SNVS_LPSR               0x18
+#define SNVS_LPSRTCMR           0x1c
+#define SNVS_LPSRTCLR           0x20
+#define SNVS_LPTAR              0x24
+#define SNVS_LPPGDR             0x30
+
+#define SNVS_LPCR_SRTC_ENV      (1 << 0)
+#define SNVS_LPCR_LPTA_EN       (1 << 1)
+#define SNVS_LPCR_LPWUI_EN      (1 << 3)
+#define SNVS_LPSR_LPTA          (1 << 0)
+
+#define SNVS_LPPGDR_INIT        0x41736166
+#define CNTR_TO_SECS_SH         15
+
+struct snvs_rtc_data {
+        struct rtc_device *rtc;
+        void __iomem *ioaddr;
+        int irq;
+        spinlock_t lock;
+};
+
+static u32 rtc_read_lp_counter(void __iomem *ioaddr)
+{
+        u64 read1, read2;
+
+        do {
+                read1 = readl(ioaddr + SNVS_LPSRTCMR);
+                read1 <<= 32;
+                read1 |= readl(ioaddr + SNVS_LPSRTCLR);
+
+                read2 = readl(ioaddr + SNVS_LPSRTCMR);
+                read2 <<= 32;
+                read2 |= readl(ioaddr + SNVS_LPSRTCLR);
+        } while (read1 != read2);
+
+        /* Convert 47-bit counter to 32-bit raw second count */
+        return (u32) (read1 >> CNTR_TO_SECS_SH);
+}
+
+static void rtc_write_sync_lp(void __iomem *ioaddr)
+{
+        u32 count1, count2, count3;
+        int i;
+
+        /* Wait for 3 CKIL cycles */
+        for (i = 0; i < 3; i++) {
+                do {
+                        count1 = readl(ioaddr + SNVS_LPSRTCLR);
+                        count2 = readl(ioaddr + SNVS_LPSRTCLR);
+                } while (count1 != count2);
+
+                /* Now wait until counter value changes */
+                do {
+                        do {
+                                count2 = readl(ioaddr + SNVS_LPSRTCLR);
+                                count3 = readl(ioaddr + SNVS_LPSRTCLR);
+                        } while (count2 != count3);
+                } while (count3 == count1);
+        }
+}
+
+static int snvs_rtc_enable(struct snvs_rtc_data *data, bool enable)
+{
+        unsigned long flags;
+        int timeout = 1000;
+        u32 lpcr;
+
+        spin_lock_irqsave(&data->lock, flags);
+
+        lpcr = readl(data->ioaddr + SNVS_LPCR);
+        if (enable)
+                lpcr |= SNVS_LPCR_SRTC_ENV;
+        else
+                lpcr &= ~SNVS_LPCR_SRTC_ENV;
+        writel(lpcr, data->ioaddr + SNVS_LPCR);
+
+        spin_unlock_irqrestore(&data->lock, flags);
+
+        while (--timeout) {
+                lpcr = readl(data->ioaddr + SNVS_LPCR);
+
+                if (enable) {
+                        if (lpcr & SNVS_LPCR_SRTC_ENV)
+                                break;
+                } else {
+                        if (!(lpcr & SNVS_LPCR_SRTC_ENV))
+                                break;
+                }
+        }
+
+        if (!timeout)
+                return -ETIMEDOUT;
+
+        return 0;
+}
+
+static int snvs_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+        struct snvs_rtc_data *data = dev_get_drvdata(dev);
+        unsigned long time = rtc_read_lp_counter(data->ioaddr);
+
+        rtc_time_to_tm(time, tm);
+
+        return 0;
+}
+
+static int snvs_rtc_set_time(struct device *dev, struct rtc_time *tm)
+{
+        struct snvs_rtc_data *data = dev_get_drvdata(dev);
+        unsigned long time;
+
+        rtc_tm_to_time(tm, &time);
+
+        /* Disable RTC first */
+        snvs_rtc_enable(data, false);
+
+        /* Write 32-bit time to 47-bit timer, leaving 15 LSBs blank */
+        writel(time << CNTR_TO_SECS_SH, data->ioaddr + SNVS_LPSRTCLR);
+        writel(time >> (32 - CNTR_TO_SECS_SH), data->ioaddr + SNVS_LPSRTCMR);
+
+        /* Enable RTC again */
+        snvs_rtc_enable(data, true);
+
+        return 0;
+}
+
+static int snvs_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
+{
+        struct snvs_rtc_data *data = dev_get_drvdata(dev);
+        u32 lptar, lpsr;
+
+        lptar = readl(data->ioaddr + SNVS_LPTAR);
+        rtc_time_to_tm(lptar, &alrm->time);
+
+        lpsr = readl(data->ioaddr + SNVS_LPSR);
+        alrm->pending = (lpsr & SNVS_LPSR_LPTA) ? 1 : 0;
+
+        return 0;
+}
+
+static int snvs_rtc_alarm_irq_enable(struct device *dev, unsigned int enable)
+{
+        struct snvs_rtc_data *data = dev_get_drvdata(dev);
+        u32 lpcr;
+        unsigned long flags;
+
+        spin_lock_irqsave(&data->lock, flags);
+
+        lpcr = readl(data->ioaddr + SNVS_LPCR);
+        if (enable)
+                lpcr |= (SNVS_LPCR_LPTA_EN | SNVS_LPCR_LPWUI_EN);
+        else
+                lpcr &= ~(SNVS_LPCR_LPTA_EN | SNVS_LPCR_LPWUI_EN);
+        writel(lpcr, data->ioaddr + SNVS_LPCR);
+
+        spin_unlock_irqrestore(&data->lock, flags);
+
+        rtc_write_sync_lp(data->ioaddr);
+
+        return 0;
+}
+
+static int snvs_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
+{
+        struct snvs_rtc_data *data = dev_get_drvdata(dev);
+        struct rtc_time *alrm_tm = &alrm->time;
+        unsigned long time;
+        unsigned long flags;
+        u32 lpcr;
+
+        rtc_tm_to_time(alrm_tm, &time);
+
+        spin_lock_irqsave(&data->lock, flags);
+
+        /* Have to clear LPTA_EN before programming new alarm time in LPTAR */
+        lpcr = readl(data->ioaddr + SNVS_LPCR);
+        lpcr &= ~SNVS_LPCR_LPTA_EN;
+        writel(lpcr, data->ioaddr + SNVS_LPCR);
+
+        spin_unlock_irqrestore(&data->lock, flags);
+
+        writel(time, data->ioaddr + SNVS_LPTAR);
+
+        /* Clear alarm interrupt status bit */
+        writel(SNVS_LPSR_LPTA, data->ioaddr + SNVS_LPSR);
+
+        return snvs_rtc_alarm_irq_enable(dev, alrm->enabled);
+}
+
+static const struct rtc_class_ops snvs_rtc_ops = {
+        .read_time = snvs_rtc_read_time,
+        .set_time = snvs_rtc_set_time,
+        .read_alarm = snvs_rtc_read_alarm,
+        .set_alarm = snvs_rtc_set_alarm,
+        .alarm_irq_enable = snvs_rtc_alarm_irq_enable,
+};
+
+static irqreturn_t snvs_rtc_irq_handler(int irq, void *dev_id)
+{
+        struct device *dev = dev_id;
+        struct snvs_rtc_data *data = dev_get_drvdata(dev);
+        u32 lpsr;
+        u32 events = 0;
+
+        lpsr = readl(data->ioaddr + SNVS_LPSR);
+
+        if (lpsr & SNVS_LPSR_LPTA) {
+                events |= (RTC_AF | RTC_IRQF);
+
+                /* RTC alarm should be one-shot */
+                snvs_rtc_alarm_irq_enable(dev, 0);
+
+                rtc_update_irq(data->rtc, 1, events);
+        }
+
+        /* clear interrupt status */
+        writel(lpsr, data->ioaddr + SNVS_LPSR);
+
+        return events ? IRQ_HANDLED : IRQ_NONE;
+}
+
+static int __devinit snvs_rtc_probe(struct platform_device *pdev)
+{
+        struct snvs_rtc_data *data;
+        struct resource *res;
+        int ret;
+
+        data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
+        if (!data)
+                return -ENOMEM;
+
+        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+        data->ioaddr = devm_request_and_ioremap(&pdev->dev, res);
+        if (!data->ioaddr)
+                return -EADDRNOTAVAIL;
+
+        data->irq = platform_get_irq(pdev, 0);
+        if (data->irq < 0)
+                return data->irq;
+
+        platform_set_drvdata(pdev, data);
+
+        spin_lock_init(&data->lock);
+
+        /* Initialize glitch detect */
+        writel(SNVS_LPPGDR_INIT, data->ioaddr + SNVS_LPPGDR);
+
+        /* Clear interrupt status */
+        writel(0xffffffff, data->ioaddr + SNVS_LPSR);
+
+        /* Enable RTC */
+        snvs_rtc_enable(data, true);
+
+        device_init_wakeup(&pdev->dev, true);
+
+        ret = devm_request_irq(&pdev->dev, data->irq, snvs_rtc_irq_handler,
+                               IRQF_SHARED, "rtc alarm", &pdev->dev);
+        if (ret) {
+                dev_err(&pdev->dev, "failed to request irq %d: %d\n",
+                        data->irq, ret);
+                return ret;
+        }
+
+        data->rtc = rtc_device_register(pdev->name, &pdev->dev,
+                                        &snvs_rtc_ops, THIS_MODULE);
+        if (IS_ERR(data->rtc)) {
+                ret = PTR_ERR(data->rtc);
+                dev_err(&pdev->dev, "failed to register rtc: %d\n", ret);
+                return ret;
+        }
+
+        return 0;
+}
+
+static int __devexit snvs_rtc_remove(struct platform_device *pdev)
+{
+        struct snvs_rtc_data *data = platform_get_drvdata(pdev);
+
+        rtc_device_unregister(data->rtc);
+
+        return 0;
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int snvs_rtc_suspend(struct device *dev)
+{
+        struct snvs_rtc_data *data = dev_get_drvdata(dev);
+
+        if (device_may_wakeup(dev))
+                enable_irq_wake(data->irq);
+
+        return 0;
+}
+
+static int snvs_rtc_resume(struct device *dev)
+{
+        struct snvs_rtc_data *data = dev_get_drvdata(dev);
+
+        if (device_may_wakeup(dev))
+                disable_irq_wake(data->irq);
+
+        return 0;
+}
+#endif
+
+static SIMPLE_DEV_PM_OPS(snvs_rtc_pm_ops, snvs_rtc_suspend, snvs_rtc_resume);
+
+static const struct of_device_id __devinitconst snvs_dt_ids[] = {
+        { .compatible = "fsl,sec-v4.0-mon-rtc-lp", },
+        { /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, snvs_dt_ids);
+
+static struct platform_driver snvs_rtc_driver = {
+        .driver = {
+                .name   = "snvs_rtc",
+                .owner  = THIS_MODULE,
+                .pm     = &snvs_rtc_pm_ops,
+                .of_match_table = snvs_dt_ids,
+        },
+        .probe          = snvs_rtc_probe,
+        .remove         = __devexit_p(snvs_rtc_remove),
+};
+module_platform_driver(snvs_rtc_driver);
+
+MODULE_AUTHOR("Freescale Semiconductor, Inc.");
+MODULE_DESCRIPTION("Freescale SNVS RTC Driver");
+MODULE_LICENSE("GPL");