drivers/rtc/rtc-sirfsoc.c: add rtc drivers for CSR SiRFprimaII and SiRFatlasVI

On CSR SiRFprimaII/atlasVI, there is a programmable 16-bit divider
(RTC_DIV) that divides the input 32.768KHz clock to the frequency that
users need (E.g.  1 Hz).  The divided real-time clock will be used to
drive a 32-bit counter (RTC_COUNTER) that provides users with the actual
time.

In each cycle of the divided real-time clock, there is a Hertz interrupt
generated to the RISC.  Users can also configure an alarm (RTC_ALARM).
When RTC_COUNTER matches the alarm, there will be an alarm interrupt
generated to the RISC.

The system RTC can generate an alarm wake-up signal to notify the power
controller to wake up from power saving mode.

Signed-off-by: Xianglong Du <Xianglong.Du@csr.com>
Signed-off-by: Barry Song <Baohua.Song@csr.com>
Cc: Jingoo Han <jg1.han@samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

3 files changed, 483 insertions, 0 deletions

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index 8009e5d8776a..9e3498bf302b 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -1242,6 +1242,13 @@ config RTC_DRV_SNVS
            This driver can also be built as a module, if so, the module
            will be called "rtc-snvs".
 
+config RTC_DRV_SIRFSOC
+        tristate "SiRFSOC RTC"
+        depends on ARCH_SIRF
+        help
+          Say "yes" here to support the real time clock on SiRF SOC chips.
+          This driver can also be built as a module called rtc-sirfsoc.
+
 comment "HID Sensor RTC drivers"
 
 config RTC_DRV_HID_SENSOR_TIME
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index 994a2fac8277..d3b4488f48f2 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -129,3 +129,4 @@ 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
+obj-$(CONFIG_RTC_DRV_SIRFSOC)   += rtc-sirfsoc.o
diff --git a/drivers/rtc/rtc-sirfsoc.c b/drivers/rtc/rtc-sirfsoc.c
new file mode 100644
index 000000000000..aa7ed4b5f7f0
--- /dev/null
+++ b/drivers/rtc/rtc-sirfsoc.c
@@ -0,0 +1,475 @@
+/*
+ * SiRFSoC Real Time Clock interface for Linux
+ *
+ * Copyright (c) 2013 Cambridge Silicon Radio Limited, a CSR plc group company.
+ *
+ * Licensed under GPLv2 or later.
+ */
+
+#include <linux/module.h>
+#include <linux/err.h>
+#include <linux/rtc.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/io.h>
+#include <linux/of.h>
+#include <linux/rtc/sirfsoc_rtciobrg.h>
+
+
+#define RTC_CN                  0x00
+#define RTC_ALARM0              0x04
+#define RTC_ALARM1              0x18
+#define RTC_STATUS              0x08
+#define RTC_SW_VALUE            0x40
+#define SIRFSOC_RTC_AL1E        (1<<6)
+#define SIRFSOC_RTC_AL1         (1<<4)
+#define SIRFSOC_RTC_HZE         (1<<3)
+#define SIRFSOC_RTC_AL0E        (1<<2)
+#define SIRFSOC_RTC_HZ          (1<<1)
+#define SIRFSOC_RTC_AL0         (1<<0)
+#define RTC_DIV                 0x0c
+#define RTC_DEEP_CTRL           0x14
+#define RTC_CLOCK_SWITCH        0x1c
+#define SIRFSOC_RTC_CLK         0x03    /* others are reserved */
+
+/* Refer to RTC DIV switch */
+#define RTC_HZ                  16
+
+/* This macro is also defined in arch/arm/plat-sirfsoc/cpu.c */
+#define RTC_SHIFT               4
+
+#define INTR_SYSRTC_CN          0x48
+
+struct sirfsoc_rtc_drv {
+        struct rtc_device       *rtc;
+        u32                     rtc_base;
+        u32                     irq;
+        /* Overflow for every 8 years extra time */
+        u32                     overflow_rtc;
+#ifdef CONFIG_PM
+        u32             saved_counter;
+        u32             saved_overflow_rtc;
+#endif
+};
+
+static int sirfsoc_rtc_read_alarm(struct device *dev,
+                struct rtc_wkalrm *alrm)
+{
+        unsigned long rtc_alarm, rtc_count;
+        struct sirfsoc_rtc_drv *rtcdrv;
+
+        rtcdrv = (struct sirfsoc_rtc_drv *)dev_get_drvdata(dev);
+
+        local_irq_disable();
+
+        rtc_count = sirfsoc_rtc_iobrg_readl(rtcdrv->rtc_base + RTC_CN);
+
+        rtc_alarm = sirfsoc_rtc_iobrg_readl(rtcdrv->rtc_base + RTC_ALARM0);
+        memset(alrm, 0, sizeof(struct rtc_wkalrm));
+
+        /*
+         * assume alarm interval not beyond one round counter overflow_rtc:
+         * 0->0xffffffff
+         */
+        /* if alarm is in next overflow cycle */
+        if (rtc_count > rtc_alarm)
+                rtc_time_to_tm((rtcdrv->overflow_rtc + 1)
+                                << (BITS_PER_LONG - RTC_SHIFT)
+                                | rtc_alarm >> RTC_SHIFT, &(alrm->time));
+        else
+                rtc_time_to_tm(rtcdrv->overflow_rtc
+                                << (BITS_PER_LONG - RTC_SHIFT)
+                                | rtc_alarm >> RTC_SHIFT, &(alrm->time));
+        if (sirfsoc_rtc_iobrg_readl(
+                        rtcdrv->rtc_base + RTC_STATUS) & SIRFSOC_RTC_AL0E)
+                alrm->enabled = 1;
+        local_irq_enable();
+
+        return 0;
+}
+
+static int sirfsoc_rtc_set_alarm(struct device *dev,
+                struct rtc_wkalrm *alrm)
+{
+        unsigned long rtc_status_reg, rtc_alarm;
+        struct sirfsoc_rtc_drv *rtcdrv;
+        rtcdrv = (struct sirfsoc_rtc_drv *)dev_get_drvdata(dev);
+
+        if (alrm->enabled) {
+                rtc_tm_to_time(&(alrm->time), &rtc_alarm);
+
+                local_irq_disable();
+
+                rtc_status_reg = sirfsoc_rtc_iobrg_readl(
+                                rtcdrv->rtc_base + RTC_STATUS);
+                if (rtc_status_reg & SIRFSOC_RTC_AL0E) {
+                        /*
+                         * An ongoing alarm in progress - ingore it and not
+                         * to return EBUSY
+                         */
+                        dev_info(dev, "An old alarm was set, will be replaced by a new one\n");
+                }
+
+                sirfsoc_rtc_iobrg_writel(
+                        rtc_alarm << RTC_SHIFT, rtcdrv->rtc_base + RTC_ALARM0);
+                rtc_status_reg &= ~0x07; /* mask out the lower status bits */
+                /*
+                 * This bit RTC_AL sets it as a wake-up source for Sleep Mode
+                 * Writing 1 into this bit will clear it
+                 */
+                rtc_status_reg |= SIRFSOC_RTC_AL0;
+                /* enable the RTC alarm interrupt */
+                rtc_status_reg |= SIRFSOC_RTC_AL0E;
+                sirfsoc_rtc_iobrg_writel(
+                        rtc_status_reg, rtcdrv->rtc_base + RTC_STATUS);
+                local_irq_enable();
+        } else {
+                /*
+                 * if this function was called with enabled=0
+                 * then it could mean that the application is
+                 * trying to cancel an ongoing alarm
+                 */
+                local_irq_disable();
+
+                rtc_status_reg = sirfsoc_rtc_iobrg_readl(
+                                rtcdrv->rtc_base + RTC_STATUS);
+                if (rtc_status_reg & SIRFSOC_RTC_AL0E) {
+                        /* clear the RTC status register's alarm bit */
+                        rtc_status_reg &= ~0x07;
+                        /* write 1 into SIRFSOC_RTC_AL0 to force a clear */
+                        rtc_status_reg |= (SIRFSOC_RTC_AL0);
+                        /* Clear the Alarm enable bit */
+                        rtc_status_reg &= ~(SIRFSOC_RTC_AL0E);
+
+                        sirfsoc_rtc_iobrg_writel(rtc_status_reg,
+                                        rtcdrv->rtc_base + RTC_STATUS);
+                }
+
+                local_irq_enable();
+        }
+
+        return 0;
+}
+
+static int sirfsoc_rtc_read_time(struct device *dev,
+                struct rtc_time *tm)
+{
+        unsigned long tmp_rtc = 0;
+        struct sirfsoc_rtc_drv *rtcdrv;
+        rtcdrv = (struct sirfsoc_rtc_drv *)dev_get_drvdata(dev);
+        /*
+         * This patch is taken from WinCE - Need to validate this for
+         * correctness. To work around sirfsoc RTC counter double sync logic
+         * fail, read several times to make sure get stable value.
+         */
+        do {
+                tmp_rtc = sirfsoc_rtc_iobrg_readl(rtcdrv->rtc_base + RTC_CN);
+                cpu_relax();
+        } while (tmp_rtc != sirfsoc_rtc_iobrg_readl(rtcdrv->rtc_base + RTC_CN));
+
+        rtc_time_to_tm(rtcdrv->overflow_rtc << (BITS_PER_LONG - RTC_SHIFT) |
+                                        tmp_rtc >> RTC_SHIFT, tm);
+        return 0;
+}
+
+static int sirfsoc_rtc_set_time(struct device *dev,
+                struct rtc_time *tm)
+{
+        unsigned long rtc_time;
+        struct sirfsoc_rtc_drv *rtcdrv;
+        rtcdrv = (struct sirfsoc_rtc_drv *)dev_get_drvdata(dev);
+
+        rtc_tm_to_time(tm, &rtc_time);
+
+        rtcdrv->overflow_rtc = rtc_time >> (BITS_PER_LONG - RTC_SHIFT);
+
+        sirfsoc_rtc_iobrg_writel(rtcdrv->overflow_rtc,
+                        rtcdrv->rtc_base + RTC_SW_VALUE);
+        sirfsoc_rtc_iobrg_writel(
+                        rtc_time << RTC_SHIFT, rtcdrv->rtc_base + RTC_CN);
+
+        return 0;
+}
+
+static int sirfsoc_rtc_ioctl(struct device *dev, unsigned int cmd,
+                unsigned long arg)
+{
+        switch (cmd) {
+        case RTC_PIE_ON:
+        case RTC_PIE_OFF:
+        case RTC_UIE_ON:
+        case RTC_UIE_OFF:
+        case RTC_AIE_ON:
+        case RTC_AIE_OFF:
+                return 0;
+
+        default:
+                return -ENOIOCTLCMD;
+        }
+}
+
+static const struct rtc_class_ops sirfsoc_rtc_ops = {
+        .read_time = sirfsoc_rtc_read_time,
+        .set_time = sirfsoc_rtc_set_time,
+        .read_alarm = sirfsoc_rtc_read_alarm,
+        .set_alarm = sirfsoc_rtc_set_alarm,
+        .ioctl = sirfsoc_rtc_ioctl
+};
+
+static irqreturn_t sirfsoc_rtc_irq_handler(int irq, void *pdata)
+{
+        struct sirfsoc_rtc_drv *rtcdrv = pdata;
+        unsigned long rtc_status_reg = 0x0;
+        unsigned long events = 0x0;
+
+        rtc_status_reg = sirfsoc_rtc_iobrg_readl(rtcdrv->rtc_base + RTC_STATUS);
+        /* this bit will be set ONLY if an alarm was active
+         * and it expired NOW
+         * So this is being used as an ASSERT
+         */
+        if (rtc_status_reg & SIRFSOC_RTC_AL0) {
+                /*
+                 * clear the RTC status register's alarm bit
+                 * mask out the lower status bits
+                 */
+                rtc_status_reg &= ~0x07;
+                /* write 1 into SIRFSOC_RTC_AL0 to ACK the alarm interrupt */
+                rtc_status_reg |= (SIRFSOC_RTC_AL0);
+                /* Clear the Alarm enable bit */
+                rtc_status_reg &= ~(SIRFSOC_RTC_AL0E);
+        }
+        sirfsoc_rtc_iobrg_writel(rtc_status_reg, rtcdrv->rtc_base + RTC_STATUS);
+        /* this should wake up any apps polling/waiting on the read
+         * after setting the alarm
+         */
+        events |= RTC_IRQF | RTC_AF;
+        rtc_update_irq(rtcdrv->rtc, 1, events);
+
+        return IRQ_HANDLED;
+}
+
+static const struct of_device_id sirfsoc_rtc_of_match[] = {
+        { .compatible = "sirf,prima2-sysrtc"},
+        {},
+};
+MODULE_DEVICE_TABLE(of, sirfsoc_rtc_of_match);
+
+static int sirfsoc_rtc_probe(struct platform_device *pdev)
+{
+        int err;
+        unsigned long rtc_div;
+        struct sirfsoc_rtc_drv *rtcdrv;
+        struct device_node *np = pdev->dev.of_node;
+
+        rtcdrv = devm_kzalloc(&pdev->dev,
+                sizeof(struct sirfsoc_rtc_drv), GFP_KERNEL);
+        if (rtcdrv == NULL) {
+                dev_err(&pdev->dev,
+                        "%s: can't alloc mem for drv struct\n",
+                        pdev->name);
+                return -ENOMEM;
+        }
+
+        err = of_property_read_u32(np, "reg", &rtcdrv->rtc_base);
+        if (err) {
+                dev_err(&pdev->dev, "unable to find base address of rtc node in dtb\n");
+                goto error;
+        }
+
+        platform_set_drvdata(pdev, rtcdrv);
+
+        /* Register rtc alarm as a wakeup source */
+        device_init_wakeup(&pdev->dev, 1);
+
+        /*
+         * Set SYS_RTC counter in RTC_HZ HZ Units
+         * We are using 32K RTC crystal (32768 / RTC_HZ / 2) -1
+         * If 16HZ, therefore RTC_DIV = 1023;
+         */
+        rtc_div = ((32768 / RTC_HZ) / 2) - 1;
+        sirfsoc_rtc_iobrg_writel(rtc_div, rtcdrv->rtc_base + RTC_DIV);
+
+        rtcdrv->rtc = rtc_device_register(pdev->name, &(pdev->dev),
+                        &sirfsoc_rtc_ops, THIS_MODULE);
+        if (IS_ERR(rtcdrv->rtc)) {
+                err = PTR_ERR(rtcdrv->rtc);
+                dev_err(&pdev->dev, "can't register RTC device\n");
+                return err;
+        }
+
+        /* 0x3 -> RTC_CLK */
+        sirfsoc_rtc_iobrg_writel(SIRFSOC_RTC_CLK,
+                        rtcdrv->rtc_base + RTC_CLOCK_SWITCH);
+
+        /* reset SYS RTC ALARM0 */
+        sirfsoc_rtc_iobrg_writel(0x0, rtcdrv->rtc_base + RTC_ALARM0);
+
+        /* reset SYS RTC ALARM1 */
+        sirfsoc_rtc_iobrg_writel(0x0, rtcdrv->rtc_base + RTC_ALARM1);
+
+        /* Restore RTC Overflow From Register After Command Reboot */
+        rtcdrv->overflow_rtc =
+                sirfsoc_rtc_iobrg_readl(rtcdrv->rtc_base + RTC_SW_VALUE);
+
+        rtcdrv->irq = platform_get_irq(pdev, 0);
+        err = devm_request_irq(
+                        &pdev->dev,
+                        rtcdrv->irq,
+                        sirfsoc_rtc_irq_handler,
+                        IRQF_SHARED,
+                        pdev->name,
+                        rtcdrv);
+        if (err) {
+                dev_err(&pdev->dev, "Unable to register for the SiRF SOC RTC IRQ\n");
+                goto error;
+        }
+
+        return 0;
+
+error:
+        if (rtcdrv->rtc)
+                rtc_device_unregister(rtcdrv->rtc);
+
+        return err;
+}
+
+static int sirfsoc_rtc_remove(struct platform_device *pdev)
+{
+        struct sirfsoc_rtc_drv *rtcdrv = platform_get_drvdata(pdev);
+
+        device_init_wakeup(&pdev->dev, 0);
+        rtc_device_unregister(rtcdrv->rtc);
+
+        return 0;
+}
+
+#ifdef CONFIG_PM
+
+static int sirfsoc_rtc_suspend(struct device *dev)
+{
+        struct platform_device *pdev = to_platform_device(dev);
+        struct sirfsoc_rtc_drv *rtcdrv = platform_get_drvdata(pdev);
+        rtcdrv->overflow_rtc =
+                sirfsoc_rtc_iobrg_readl(rtcdrv->rtc_base + RTC_SW_VALUE);
+
+        rtcdrv->saved_counter =
+                sirfsoc_rtc_iobrg_readl(rtcdrv->rtc_base + RTC_CN);
+        rtcdrv->saved_overflow_rtc = rtcdrv->overflow_rtc;
+        if (device_may_wakeup(&pdev->dev))
+                enable_irq_wake(rtcdrv->irq);
+
+        return 0;
+}
+
+static int sirfsoc_rtc_freeze(struct device *dev)
+{
+        sirfsoc_rtc_suspend(dev);
+
+        return 0;
+}
+
+static int sirfsoc_rtc_thaw(struct device *dev)
+{
+        u32 tmp;
+        struct sirfsoc_rtc_drv *rtcdrv;
+        rtcdrv = (struct sirfsoc_rtc_drv *)dev_get_drvdata(dev);
+
+        /*
+         * if resume from snapshot and the rtc power is losed,
+         * restroe the rtc settings
+         */
+        if (SIRFSOC_RTC_CLK != sirfsoc_rtc_iobrg_readl(
+                        rtcdrv->rtc_base + RTC_CLOCK_SWITCH)) {
+                u32 rtc_div;
+                /* 0x3 -> RTC_CLK */
+                sirfsoc_rtc_iobrg_writel(SIRFSOC_RTC_CLK,
+                        rtcdrv->rtc_base + RTC_CLOCK_SWITCH);
+                /*
+                 * Set SYS_RTC counter in RTC_HZ HZ Units
+                 * We are using 32K RTC crystal (32768 / RTC_HZ / 2) -1
+                 * If 16HZ, therefore RTC_DIV = 1023;
+                 */
+                rtc_div = ((32768 / RTC_HZ) / 2) - 1;
+
+                sirfsoc_rtc_iobrg_writel(rtc_div, rtcdrv->rtc_base + RTC_DIV);
+
+                /* reset SYS RTC ALARM0 */
+                sirfsoc_rtc_iobrg_writel(0x0, rtcdrv->rtc_base + RTC_ALARM0);
+
+                /* reset SYS RTC ALARM1 */
+                sirfsoc_rtc_iobrg_writel(0x0, rtcdrv->rtc_base + RTC_ALARM1);
+        }
+        rtcdrv->overflow_rtc = rtcdrv->saved_overflow_rtc;
+
+        /*
+         * if current counter is small than previous,
+         * it means overflow in sleep
+         */
+        tmp = sirfsoc_rtc_iobrg_readl(rtcdrv->rtc_base + RTC_CN);
+        if (tmp <= rtcdrv->saved_counter)
+                rtcdrv->overflow_rtc++;
+        /*
+         *PWRC Value Be Changed When Suspend, Restore Overflow
+         * In Memory To Register
+         */
+        sirfsoc_rtc_iobrg_writel(rtcdrv->overflow_rtc,
+                        rtcdrv->rtc_base + RTC_SW_VALUE);
+
+        return 0;
+}
+
+static int sirfsoc_rtc_resume(struct device *dev)
+{
+        struct platform_device *pdev = to_platform_device(dev);
+        struct sirfsoc_rtc_drv *rtcdrv = platform_get_drvdata(pdev);
+        sirfsoc_rtc_thaw(dev);
+        if (device_may_wakeup(&pdev->dev))
+                disable_irq_wake(rtcdrv->irq);
+
+        return 0;
+}
+
+static int sirfsoc_rtc_restore(struct device *dev)
+{
+        struct platform_device *pdev = to_platform_device(dev);
+        struct sirfsoc_rtc_drv *rtcdrv = platform_get_drvdata(pdev);
+
+        if (device_may_wakeup(&pdev->dev))
+                disable_irq_wake(rtcdrv->irq);
+        return 0;
+}
+
+#else
+#define sirfsoc_rtc_suspend     NULL
+#define sirfsoc_rtc_resume      NULL
+#define sirfsoc_rtc_freeze      NULL
+#define sirfsoc_rtc_thaw        NULL
+#define sirfsoc_rtc_restore     NULL
+#endif
+
+static const struct dev_pm_ops sirfsoc_rtc_pm_ops = {
+        .suspend = sirfsoc_rtc_suspend,
+        .resume = sirfsoc_rtc_resume,
+        .freeze = sirfsoc_rtc_freeze,
+        .thaw = sirfsoc_rtc_thaw,
+        .restore = sirfsoc_rtc_restore,
+};
+
+static struct platform_driver sirfsoc_rtc_driver = {
+        .driver = {
+                .name = "sirfsoc-rtc",
+                .owner = THIS_MODULE,
+#ifdef CONFIG_PM
+                .pm = &sirfsoc_rtc_pm_ops,
+#endif
+                .of_match_table = of_match_ptr(sirfsoc_rtc_of_match),
+        },
+        .probe = sirfsoc_rtc_probe,
+        .remove = sirfsoc_rtc_remove,
+};
+module_platform_driver(sirfsoc_rtc_driver);
+
+MODULE_DESCRIPTION("SiRF SoC rtc driver");
+MODULE_AUTHOR("Xianglong Du <Xianglong.Du@csr.com>");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:sirfsoc-rtc");