rtc-ds1511: fix races around device registration

- Call dev_set_drvdata before rtc device creation.

- Use its own spinlock instead of rtc->irq_lock.  Because pdata->rtc
  must be initialized to use the irq_lock (pdata->rtc->irq_lock).  There
  is a small window which rtc methods can be called before pdata->rtc is
  initialized.

  And there is no need use the irq_lock to protect hardware registers.
  The driver's own spinlock shoule be enough.

- Check pdata->rtc before calling rtc_update_irq.

- Use {alarm,update}_irq_enable and remove ioctl routine.

- Use devres APIs and simplify error/remove path.

These fixes are ported from ds1553 driver and just compile-tested only.

Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Cc: Andrew Sharp <andy.sharp@lsi.com>
Cc: Thomas Hommel <thomas.hommel@gefanuc.com>
Cc: David Brownell <david-b@pacbell.net>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 60 insertions, 88 deletions

diff --git a/drivers/rtc/rtc-ds1511.c b/drivers/rtc/rtc-ds1511.c
index 539676e25fd8..4166b84cb514 100644
--- a/drivers/rtc/rtc-ds1511.c
+++ b/drivers/rtc/rtc-ds1511.c
@@ -87,7 +87,6 @@ enum ds1511reg {
 struct rtc_plat_data {
         struct rtc_device *rtc;
         void __iomem *ioaddr;           /* virtual base address */
-        unsigned long baseaddr;         /* physical base address */
         int size;                               /* amount of memory mapped */
         int irq;
         unsigned int irqen;
@@ -95,6 +94,7 @@ struct rtc_plat_data {
         int alrm_min;
         int alrm_hour;
         int alrm_mday;
+        spinlock_t lock;
 };
 
 static DEFINE_SPINLOCK(ds1511_lock);
@@ -302,7 +302,7 @@ ds1511_rtc_update_alarm(struct rtc_plat_data *pdata)
 {
         unsigned long flags;
 
-        spin_lock_irqsave(&pdata->rtc->irq_lock, flags);
+        spin_lock_irqsave(&pdata->lock, flags);
         rtc_write(pdata->alrm_mday < 0 || (pdata->irqen & RTC_UF) ?
                0x80 : bin2bcd(pdata->alrm_mday) & 0x3f,
                RTC_ALARM_DATE);
@@ -317,7 +317,7 @@ ds1511_rtc_update_alarm(struct rtc_plat_data *pdata)
                RTC_ALARM_SEC);
         rtc_write(rtc_read(RTC_CMD) | (pdata->irqen ? RTC_TIE : 0), RTC_CMD);
         rtc_read(RTC_CMD1);     /* clear interrupts */
-        spin_unlock_irqrestore(&pdata->rtc->irq_lock, flags);
+        spin_unlock_irqrestore(&pdata->lock, flags);
 }
 
  static int
@@ -362,61 +362,63 @@ ds1511_interrupt(int irq, void *dev_id)
 {
         struct platform_device *pdev = dev_id;
         struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
-        unsigned long events = RTC_IRQF;
+        unsigned long events = 0;
 
+        spin_lock(&pdata->lock);
         /*
          * read and clear interrupt
          */
-        if (!(rtc_read(RTC_CMD1) & DS1511_IRQF)) {
-                return IRQ_NONE;
-        }
-        if (rtc_read(RTC_ALARM_SEC) & 0x80) {
-                events |= RTC_UF;
-        } else {
-                events |= RTC_AF;
-        }
-        rtc_update_irq(pdata->rtc, 1, events);
-        return IRQ_HANDLED;
+        if (rtc_read(RTC_CMD1) & DS1511_IRQF) {
+                events = RTC_IRQF;
+                if (rtc_read(RTC_ALARM_SEC) & 0x80)
+                        events |= RTC_UF;
+                else
+                        events |= RTC_AF;
+                if (likely(pdata->rtc))
+                        rtc_update_irq(pdata->rtc, 1, events);
+        }
+        spin_unlock(&pdata->lock);
+        return events ? IRQ_HANDLED : IRQ_NONE;
 }
 
- static int
-ds1511_rtc_ioctl(struct device *dev, unsigned int cmd, unsigned long arg)
+static int ds1511_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
 {
         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;
-                ds1511_rtc_update_alarm(pdata);
-                break;
-        case RTC_AIE_ON:
+        if (pdata->irq <= 0)
+                return -EINVAL;
+        if (enabled)
                 pdata->irqen |= RTC_AF;
-                ds1511_rtc_update_alarm(pdata);
-                break;
-        case RTC_UIE_OFF:
-                pdata->irqen &= ~RTC_UF;
-                ds1511_rtc_update_alarm(pdata);
-                break;
-        case RTC_UIE_ON:
+        else
+                pdata->irqen &= ~RTC_AF;
+        ds1511_rtc_update_alarm(pdata);
+        return 0;
+}
+
+static int ds1511_rtc_update_irq_enable(struct device *dev,
+        unsigned int enabled)
+{
+        struct platform_device *pdev = to_platform_device(dev);
+        struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
+
+        if (pdata->irq <= 0)
+                return -EINVAL;
+        if (enabled)
                 pdata->irqen |= RTC_UF;
-                ds1511_rtc_update_alarm(pdata);
-                break;
-        default:
-                return -ENOIOCTLCMD;
-        }
+        else
+                pdata->irqen &= ~RTC_UF;
+        ds1511_rtc_update_alarm(pdata);
         return 0;
 }
 
 static const struct rtc_class_ops ds1511_rtc_ops = {
-        .read_time      = ds1511_rtc_read_time,
-        .set_time       = ds1511_rtc_set_time,
-        .read_alarm     = ds1511_rtc_read_alarm,
-        .set_alarm      = ds1511_rtc_set_alarm,
-        .ioctl          = ds1511_rtc_ioctl,
+        .read_time              = ds1511_rtc_read_time,
+        .set_time               = ds1511_rtc_set_time,
+        .read_alarm             = ds1511_rtc_read_alarm,
+        .set_alarm              = ds1511_rtc_set_alarm,
+        .alarm_irq_enable       = ds1511_rtc_alarm_irq_enable,
+        .update_irq_enable      = ds1511_rtc_update_irq_enable,
 };
 
  static ssize_t
@@ -492,29 +494,23 @@ ds1511_rtc_probe(struct platform_device *pdev)
 {
         struct rtc_device *rtc;
         struct resource *res;
-        struct rtc_plat_data *pdata = NULL;
+        struct rtc_plat_data *pdata;
         int ret = 0;
 
         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
         if (!res) {
                 return -ENODEV;
         }
-        pdata = kzalloc(sizeof(*pdata), GFP_KERNEL);
-        if (!pdata) {
+        pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
+        if (!pdata)
                 return -ENOMEM;
-        }
         pdata->size = res->end - res->start + 1;
-        if (!request_mem_region(res->start, pdata->size, pdev->name)) {
-                ret = -EBUSY;
-                goto out;
-        }
-        pdata->baseaddr = res->start;
-        pdata->size = pdata->size;
-        ds1511_base = ioremap(pdata->baseaddr, pdata->size);
-        if (!ds1511_base) {
-                ret = -ENOMEM;
-                goto out;
-        }
+        if (!devm_request_mem_region(&pdev->dev, res->start, pdata->size,
+                        pdev->name))
+                return -EBUSY;
+        ds1511_base = devm_ioremap(&pdev->dev, res->start, pdata->size);
+        if (!ds1511_base)
+                return -ENOMEM;
         pdata->ioaddr = ds1511_base;
         pdata->irq = platform_get_irq(pdev, 0);
 
@@ -540,13 +536,15 @@ ds1511_rtc_probe(struct platform_device *pdev)
                 dev_warn(&pdev->dev, "voltage-low detected.\n");
         }
 
+        spin_lock_init(&pdata->lock);
+        platform_set_drvdata(pdev, pdata);
         /*
          * if the platform has an interrupt in mind for this device,
          * then by all means, set it
          */
         if (pdata->irq > 0) {
                 rtc_read(RTC_CMD1);
-                if (request_irq(pdata->irq, ds1511_interrupt,
+                if (devm_request_irq(&pdev->dev, pdata->irq, ds1511_interrupt,
                         IRQF_DISABLED | IRQF_SHARED, pdev->name, pdev) < 0) {
 
                         dev_warn(&pdev->dev, "interrupt not available.\n");
@@ -556,33 +554,13 @@ ds1511_rtc_probe(struct platform_device *pdev)
 
         rtc = rtc_device_register(pdev->name, &pdev->dev, &ds1511_rtc_ops,
                 THIS_MODULE);
-        if (IS_ERR(rtc)) {
-                ret = PTR_ERR(rtc);
-                goto out;
-        }
+        if (IS_ERR(rtc))
+                return PTR_ERR(rtc);
         pdata->rtc = rtc;
-        platform_set_drvdata(pdev, pdata);
+
         ret = sysfs_create_bin_file(&pdev->dev.kobj, &ds1511_nvram_attr);
-        if (ret) {
-                goto out;
-        }
-        return 0;
- out:
-        if (pdata->rtc) {
+        if (ret)
                 rtc_device_unregister(pdata->rtc);
-        }
-        if (pdata->irq > 0) {
-                free_irq(pdata->irq, pdev);
-        }
-        if (ds1511_base) {
-                iounmap(ds1511_base);
-                ds1511_base = NULL;
-        }
-        if (pdata->baseaddr) {
-                release_mem_region(pdata->baseaddr, pdata->size);
-        }
-
-        kfree(pdata);
         return ret;
 }
 
@@ -593,19 +571,13 @@ ds1511_rtc_remove(struct platform_device *pdev)
 
         sysfs_remove_bin_file(&pdev->dev.kobj, &ds1511_nvram_attr);
         rtc_device_unregister(pdata->rtc);
-        pdata->rtc = NULL;
         if (pdata->irq > 0) {
                 /*
                  * disable the alarm interrupt
                  */
                 rtc_write(rtc_read(RTC_CMD) & ~RTC_TIE, RTC_CMD);
                 rtc_read(RTC_CMD1);
-                free_irq(pdata->irq, pdev);
         }
-        iounmap(pdata->ioaddr);
-        ds1511_base = NULL;
-        release_mem_region(pdata->baseaddr, pdata->size);
-        kfree(pdata);
         return 0;
 }