rtc-stk17ta8: 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_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: Alessandro Zummo <alessandro.zummo@towertech.it>
Cc: Thomas Hommel <thomas.hommel@gefanuc.com>
Cc: David Brownell <david-b@pacbell.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 45 insertions, 69 deletions

diff --git a/drivers/rtc/rtc-stk17ta8.c b/drivers/rtc/rtc-stk17ta8.c
index 62c2969436a..31ea22070e3 100644
--- a/drivers/rtc/rtc-stk17ta8.c
+++ b/drivers/rtc/rtc-stk17ta8.c
@@ -62,7 +62,6 @@
 struct rtc_plat_data {
         struct rtc_device *rtc;
         void __iomem *ioaddr;
-        unsigned long baseaddr;
         unsigned long last_jiffies;
         int irq;
         unsigned int irqen;
@@ -70,6 +69,7 @@ struct rtc_plat_data {
         int alrm_min;
         int alrm_hour;
         int alrm_mday;
+        spinlock_t lock;
 };
 
 static int stk17ta8_rtc_set_time(struct device *dev, struct rtc_time *tm)
@@ -142,7 +142,7 @@ static void stk17ta8_rtc_update_alarm(struct rtc_plat_data *pdata)
         unsigned long irqflags;
         u8 flags;
 
-        spin_lock_irqsave(&pdata->rtc->irq_lock, irqflags);
+        spin_lock_irqsave(&pdata->lock, irqflags);
 
         flags = readb(ioaddr + RTC_FLAGS);
         writeb(flags | RTC_WRITE, ioaddr + RTC_FLAGS);
@@ -162,7 +162,7 @@ static void stk17ta8_rtc_update_alarm(struct rtc_plat_data *pdata)
         writeb(pdata->irqen ? RTC_INTS_AIE : 0, ioaddr + RTC_INTERRUPTS);
         readb(ioaddr + RTC_FLAGS);      /* clear interrupts */
         writeb(flags & ~RTC_WRITE, ioaddr + RTC_FLAGS);
-        spin_unlock_irqrestore(&pdata->rtc->irq_lock, irqflags);
+        spin_unlock_irqrestore(&pdata->lock, irqflags);
 }
 
 static int stk17ta8_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
@@ -202,48 +202,45 @@ static irqreturn_t stk17ta8_rtc_interrupt(int irq, void *dev_id)
         struct platform_device *pdev = dev_id;
         struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
         void __iomem *ioaddr = pdata->ioaddr;
-        unsigned long events = RTC_IRQF;
+        unsigned long events = 0;
 
+        spin_lock(&pdata->lock);
         /* read and clear interrupt */
-        if (!(readb(ioaddr + RTC_FLAGS) & RTC_FLAGS_AF))
-                return IRQ_NONE;
-        if (readb(ioaddr + RTC_SECONDS_ALARM) & 0x80)
-                events |= RTC_UF;
-        else
-                events |= RTC_AF;
-        rtc_update_irq(pdata->rtc, 1, events);
-        return IRQ_HANDLED;
+        if (readb(ioaddr + RTC_FLAGS) & RTC_FLAGS_AF) {
+                events = RTC_IRQF;
+                if (readb(ioaddr + RTC_SECONDS_ALARM) & 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 stk17ta8_rtc_ioctl(struct device *dev, unsigned int cmd,
-                            unsigned long arg)
+static int stk17ta8_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;
-                stk17ta8_rtc_update_alarm(pdata);
-                break;
-        case RTC_AIE_ON:
+                return -EINVAL;
+        if (enabled)
                 pdata->irqen |= RTC_AF;
-                stk17ta8_rtc_update_alarm(pdata);
-                break;
-        default:
-                return -ENOIOCTLCMD;
-        }
+        else
+                pdata->irqen &= ~RTC_AF;
+        stk17ta8_rtc_update_alarm(pdata);
         return 0;
 }
 
 static const struct rtc_class_ops stk17ta8_rtc_ops = {
-        .read_time      = stk17ta8_rtc_read_time,
-        .set_time       = stk17ta8_rtc_set_time,
-        .read_alarm     = stk17ta8_rtc_read_alarm,
-        .set_alarm      = stk17ta8_rtc_set_alarm,
-        .ioctl          = stk17ta8_rtc_ioctl,
+        .read_time              = stk17ta8_rtc_read_time,
+        .set_time               = stk17ta8_rtc_set_time,
+        .read_alarm             = stk17ta8_rtc_read_alarm,
+        .set_alarm              = stk17ta8_rtc_set_alarm,
+        .alarm_irq_enable       = stk17ta8_rtc_alarm_irq_enable,
 };
 
 static ssize_t stk17ta8_nvram_read(struct kobject *kobj,
@@ -292,26 +289,22 @@ static int __devinit stk17ta8_rtc_probe(struct platform_device *pdev)
         unsigned int cal;
         unsigned int flags;
         struct rtc_plat_data *pdata;
-        void __iomem *ioaddr = NULL;
+        void __iomem *ioaddr;
         int ret = 0;
 
         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
         if (!res)
                 return -ENODEV;
 
-        pdata = kzalloc(sizeof(*pdata), GFP_KERNEL);
+        pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
         if (!pdata)
                 return -ENOMEM;
-        if (!request_mem_region(res->start, RTC_REG_SIZE, pdev->name)) {
-                ret = -EBUSY;
-                goto out;
-        }
-        pdata->baseaddr = res->start;
-        ioaddr = ioremap(pdata->baseaddr, RTC_REG_SIZE);
-        if (!ioaddr) {
-                ret = -ENOMEM;
-                goto out;
-        }
+        if (!devm_request_mem_region(&pdev->dev, res->start, RTC_REG_SIZE,
+                        pdev->name))
+                return -EBUSY;
+        ioaddr = devm_ioremap(&pdev->dev, res->start, RTC_REG_SIZE);
+        if (!ioaddr)
+                return -ENOMEM;
         pdata->ioaddr = ioaddr;
         pdata->irq = platform_get_irq(pdev, 0);
 
@@ -327,9 +320,13 @@ static int __devinit stk17ta8_rtc_probe(struct platform_device *pdev)
         if (readb(ioaddr + RTC_FLAGS) & RTC_FLAGS_PF)
                 dev_warn(&pdev->dev, "voltage-low detected.\n");
 
+        spin_lock_init(&pdata->lock);
+        pdata->last_jiffies = jiffies;
+        platform_set_drvdata(pdev, pdata);
         if (pdata->irq > 0) {
                 writeb(0, ioaddr + RTC_INTERRUPTS);
-                if (request_irq(pdata->irq, stk17ta8_rtc_interrupt,
+                if (devm_request_irq(&pdev->dev, pdata->irq,
+                                stk17ta8_rtc_interrupt,
                                 IRQF_DISABLED | IRQF_SHARED,
                                 pdev->name, pdev) < 0) {
                         dev_warn(&pdev->dev, "interrupt not available.\n");
@@ -337,30 +334,14 @@ static int __devinit stk17ta8_rtc_probe(struct platform_device *pdev)
                 }
         }
 
-        pdata->last_jiffies = jiffies;
-        platform_set_drvdata(pdev, pdata);
-
         pdata->rtc = rtc_device_register(pdev->name, &pdev->dev,
                                   &stk17ta8_rtc_ops, THIS_MODULE);
-        if (IS_ERR(pdata->rtc)) {
-                ret = PTR_ERR(pdata->rtc);
-                goto out;
-        }
+        if (IS_ERR(pdata->rtc))
+                return PTR_ERR(pdata->rtc);
 
         ret = sysfs_create_bin_file(&pdev->dev.kobj, &stk17ta8_nvram_attr);
-        if (ret) {
+        if (ret)
                 rtc_device_unregister(pdata->rtc);
-                goto out;
-        }
-        return 0;
- out:
-        if (pdata->irq > 0)
-                free_irq(pdata->irq, pdev);
-        if (ioaddr)
-                iounmap(ioaddr);
-        if (pdata->baseaddr)
-                release_mem_region(pdata->baseaddr, RTC_REG_SIZE);
-        kfree(pdata);
         return ret;
 }
 
@@ -370,13 +351,8 @@ static int __devexit stk17ta8_rtc_remove(struct platform_device *pdev)
 
         sysfs_remove_bin_file(&pdev->dev.kobj, &stk17ta8_nvram_attr);
         rtc_device_unregister(pdata->rtc);
-        if (pdata->irq > 0) {
+        if (pdata->irq > 0)
                 writeb(0, pdata->ioaddr + RTC_INTERRUPTS);
-                free_irq(pdata->irq, pdev);
-        }
-        iounmap(pdata->ioaddr);
-        release_mem_region(pdata->baseaddr, RTC_REG_SIZE);
-        kfree(pdata);
         return 0;
 }