rtc: rtc-mv: Add support for clk to avoid lockups

commit 89c58c198b252f2bc20657fdd72a2aea788c435c upstream.

The Marvell RTC on Kirkwood makes use of the runit clock. Ensure the
driver clk_prepare_enable() this clock, otherwise there is a danger
the SoC will lockup when accessing RTC registers with the clock
disabled.

Reported-by: Simon Baatz <gmbnomis@gmail.com>
Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Tested-by: Simon Baatz <gmbnomis@gmail.com>
Signed-off-by: Jason Cooper <jason@lakedaemon.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/arm/boot/dts/kirkwood.dtsi b/arch/arm/boot/dts/kirkwood.dtsi
index d6ab442..578466e 100644 (file)
--- a/arch/arm/boot/dts/kirkwood.dtsi
+++ b/arch/arm/boot/dts/kirkwood.dtsi
@@ -75,6 +75,7 @@
                        compatible = "marvell,kirkwood-rtc", "marvell,orion-rtc";
                        reg = <0x10300 0x20>;
                        interrupts = <53>;
+                       clocks = <&gate_clk 7>;
                };
 
                spi@10600 {

diff --git a/drivers/rtc/rtc-mv.c b/drivers/rtc/rtc-mv.c
index 57233c8..8f87fec 100644 (file)
--- a/drivers/rtc/rtc-mv.c
+++ b/drivers/rtc/rtc-mv.c
@@ -14,6 +14,7 @@
 #include <linux/platform_device.h>
 #include <linux/of.h>
 #include <linux/delay.h>
+#include <linux/clk.h>
 #include <linux/gfp.h>
 #include <linux/module.h>
 
@@ -41,6 +42,7 @@ struct rtc_plat_data {
        struct rtc_device *rtc;
        void __iomem *ioaddr;
        int             irq;
+       struct clk      *clk;
 };
 
 static int mv_rtc_set_time(struct device *dev, struct rtc_time *tm)
@@ -221,6 +223,7 @@ static int mv_rtc_probe(struct platform_device *pdev)
        struct rtc_plat_data *pdata;
        resource_size_t size;
        u32 rtc_time;
+       int ret = 0;
 
        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        if (!res)
@@ -239,11 +242,17 @@ static int mv_rtc_probe(struct platform_device *pdev)
        if (!pdata->ioaddr)
                return -ENOMEM;
 
+       pdata->clk = devm_clk_get(&pdev->dev, NULL);
+       /* Not all SoCs require a clock.*/
+       if (!IS_ERR(pdata->clk))
+               clk_prepare_enable(pdata->clk);
+
        /* make sure the 24 hours mode is enabled */
        rtc_time = readl(pdata->ioaddr + RTC_TIME_REG_OFFS);
        if (rtc_time & RTC_HOURS_12H_MODE) {
                dev_err(&pdev->dev, "24 Hours mode not supported.\n");
-               return -EINVAL;
+               ret = -EINVAL;
+               goto out;
        }
 
        /* make sure it is actually functional */
@@ -252,7 +261,8 @@ static int mv_rtc_probe(struct platform_device *pdev)
                rtc_time = readl(pdata->ioaddr + RTC_TIME_REG_OFFS);
                if (rtc_time == 0x01000000) {
                        dev_err(&pdev->dev, "internal RTC not ticking\n");
-                       return -ENODEV;
+                       ret = -ENODEV;
+                       goto out;
                }
        }
 
@@ -268,8 +278,10 @@ static int mv_rtc_probe(struct platform_device *pdev)
        } else
                pdata->rtc = rtc_device_register(pdev->name, &pdev->dev,
                                                 &mv_rtc_ops, THIS_MODULE);
-       if (IS_ERR(pdata->rtc))
-               return PTR_ERR(pdata->rtc);
+       if (IS_ERR(pdata->rtc)) {
+               ret = PTR_ERR(pdata->rtc);
+               goto out;
+       }
 
        if (pdata->irq >= 0) {
                writel(0, pdata->ioaddr + RTC_ALARM_INTERRUPT_MASK_REG_OFFS);
@@ -282,6 +294,11 @@ static int mv_rtc_probe(struct platform_device *pdev)
        }
 
        return 0;
+out:
+       if (!IS_ERR(pdata->clk))
+               clk_disable_unprepare(pdata->clk);
+
+       return ret;
 }
 
 static int __exit mv_rtc_remove(struct platform_device *pdev)
@@ -292,6 +309,9 @@ static int __exit mv_rtc_remove(struct platform_device *pdev)
                device_init_wakeup(&pdev->dev, 0);
 
        rtc_device_unregister(pdata->rtc);
+       if (!IS_ERR(pdata->clk))
+               clk_disable_unprepare(pdata->clk);
+
        return 0;
 }