rtc: at91rm9200: get and use slow clock

Commit dca1a4b5ff6e ("clk: at91: keep slow clk enabled to prevent system
hang") added a workaround for the slow clock as it is not properly handled
by its users.

Get and use the slow clock as it is necessary for the at91rm9200 rtc.

Acked-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>

diff --git a/drivers/rtc/rtc-at91rm9200.c b/drivers/rtc/rtc-at91rm9200.c
index c4062d9..cb62e21 100644 (file)
--- a/drivers/rtc/rtc-at91rm9200.c
+++ b/drivers/rtc/rtc-at91rm9200.c
@@ -19,6 +19,7 @@
  */
 
 #include <linux/bcd.h>
+#include <linux/clk.h>
 #include <linux/completion.h>
 #include <linux/interrupt.h>
 #include <linux/ioctl.h>
@@ -59,6 +60,7 @@ static bool suspended;
 static DEFINE_SPINLOCK(suspended_lock);
 static unsigned long cached_events;
 static u32 at91_rtc_imr;
+static struct clk *sclk;
 
 static void at91_rtc_write_ier(u32 mask)
 {
@@ -407,6 +409,16 @@ static int __init at91_rtc_probe(struct platform_device *pdev)
                return -ENOMEM;
        }
 
+       sclk = devm_clk_get(&pdev->dev, NULL);
+       if (IS_ERR(sclk))
+               return PTR_ERR(sclk);
+
+       ret = clk_prepare_enable(sclk);
+       if (ret) {
+               dev_err(&pdev->dev, "Could not enable slow clock\n");
+               return ret;
+       }
+
        at91_rtc_write(AT91_RTC_CR, 0);
        at91_rtc_write(AT91_RTC_MR, 0);         /* 24 hour mode */
 
@@ -420,7 +432,7 @@ static int __init at91_rtc_probe(struct platform_device *pdev)
                               "at91_rtc", pdev);
        if (ret) {
                dev_err(&pdev->dev, "IRQ %d already in use.\n", irq);
-               return ret;
+               goto err_clk;
        }
 
        /* cpu init code should really have flagged this device as
@@ -431,8 +443,10 @@ static int __init at91_rtc_probe(struct platform_device *pdev)
 
        rtc = devm_rtc_device_register(&pdev->dev, pdev->name,
                                &at91_rtc_ops, THIS_MODULE);
-       if (IS_ERR(rtc))
-               return PTR_ERR(rtc);
+       if (IS_ERR(rtc)) {
+               ret = PTR_ERR(rtc);
+               goto err_clk;
+       }
        platform_set_drvdata(pdev, rtc);
 
        /* enable SECEV interrupt in order to initialize at91_rtc_upd_rdy
@@ -442,6 +456,11 @@ static int __init at91_rtc_probe(struct platform_device *pdev)
 
        dev_info(&pdev->dev, "AT91 Real Time Clock driver.\n");
        return 0;
+
+err_clk:
+       clk_disable_unprepare(sclk);
+
+       return ret;
 }
 
 /*
@@ -454,6 +473,8 @@ static int __exit at91_rtc_remove(struct platform_device *pdev)
                                        AT91_RTC_SECEV | AT91_RTC_TIMEV |
                                        AT91_RTC_CALEV);
 
+       clk_disable_unprepare(sclk);
+
        return 0;
 }