rtc-ds1553: fix races around device registration

* Call dev_set_drvdata before rtc device creation
* Use its own spinlock instead of rtc->irq_lock
* 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

Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Acked-by: Alessandro Zummo <a.zummo@towertech.it>
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, 64 insertions, 77 deletions

diff --git a/drivers/rtc/rtc-ds1553.c b/drivers/rtc/rtc-ds1553.c
index 717288527c6b..dadd0f517d5a 100644
--- a/drivers/rtc/rtc-ds1553.c
+++ b/drivers/rtc/rtc-ds1553.c
@@ -18,7 +18,7 @@
 #include <linux/platform_device.h>
 #include <linux/io.h>
 
-#define DRV_VERSION "0.2"
+#define DRV_VERSION "0.3"
 
 #define RTC_REG_SIZE            0x2000
 #define RTC_OFFSET              0x1ff0
@@ -61,7 +61,6 @@
 struct rtc_plat_data {
         struct rtc_device *rtc;
         void __iomem *ioaddr;
-        resource_size_t baseaddr;
         unsigned long last_jiffies;
         int irq;
         unsigned int irqen;
@@ -69,6 +68,7 @@ struct rtc_plat_data {
         int alrm_min;
         int alrm_hour;
         int alrm_mday;
+        spinlock_t lock;
 };
 
 static int ds1553_rtc_set_time(struct device *dev, struct rtc_time *tm)
@@ -139,7 +139,7 @@ static void ds1553_rtc_update_alarm(struct rtc_plat_data *pdata)
         void __iomem *ioaddr = pdata->ioaddr;
         unsigned long flags;
 
-        spin_lock_irqsave(&pdata->rtc->irq_lock, flags);
+        spin_lock_irqsave(&pdata->lock, flags);
         writeb(pdata->alrm_mday < 0 || (pdata->irqen & RTC_UF) ?
                0x80 : bin2bcd(pdata->alrm_mday),
                ioaddr + RTC_DATE_ALARM);
@@ -154,7 +154,7 @@ static void ds1553_rtc_update_alarm(struct rtc_plat_data *pdata)
                ioaddr + RTC_SECONDS_ALARM);
         writeb(pdata->irqen ? RTC_INTS_AE : 0, ioaddr + RTC_INTERRUPTS);
         readb(ioaddr + RTC_FLAGS);      /* clear interrupts */
-        spin_unlock_irqrestore(&pdata->rtc->irq_lock, flags);
+        spin_unlock_irqrestore(&pdata->lock, flags);
 }
 
 static int ds1553_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
@@ -194,56 +194,61 @@ static irqreturn_t ds1553_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 ds1553_rtc_ioctl(struct device *dev, unsigned int cmd,
-                            unsigned long arg)
+static int ds1553_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;
-                ds1553_rtc_update_alarm(pdata);
-                break;
-        case RTC_AIE_ON:
+                return -EINVAL;
+        if (enabled)
                 pdata->irqen |= RTC_AF;
-                ds1553_rtc_update_alarm(pdata);
-                break;
-        case RTC_UIE_OFF:
-                pdata->irqen &= ~RTC_UF;
-                ds1553_rtc_update_alarm(pdata);
-                break;
-        case RTC_UIE_ON:
+        else
+                pdata->irqen &= ~RTC_AF;
+        ds1553_rtc_update_alarm(pdata);
+        return 0;
+}
+
+static int ds1553_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;
-                ds1553_rtc_update_alarm(pdata);
-                break;
-        default:
-                return -ENOIOCTLCMD;
-        }
+        else
+                pdata->irqen &= ~RTC_UF;
+        ds1553_rtc_update_alarm(pdata);
         return 0;
 }
 
 static const struct rtc_class_ops ds1553_rtc_ops = {
-        .read_time      = ds1553_rtc_read_time,
-        .set_time       = ds1553_rtc_set_time,
-        .read_alarm     = ds1553_rtc_read_alarm,
-        .set_alarm      = ds1553_rtc_set_alarm,
-        .ioctl          = ds1553_rtc_ioctl,
+        .read_time              = ds1553_rtc_read_time,
+        .set_time               = ds1553_rtc_set_time,
+        .read_alarm             = ds1553_rtc_read_alarm,
+        .set_alarm              = ds1553_rtc_set_alarm,
+        .alarm_irq_enable       = ds1553_rtc_alarm_irq_enable,
+        .update_irq_enable      = ds1553_rtc_update_irq_enable,
 };
 
 static ssize_t ds1553_nvram_read(struct kobject *kobj,
@@ -291,26 +296,23 @@ static int __devinit ds1553_rtc_probe(struct platform_device *pdev)
         struct rtc_device *rtc;
         struct resource *res;
         unsigned int cen, sec;
-        struct rtc_plat_data *pdata = NULL;
-        void __iomem *ioaddr = NULL;
+        struct rtc_plat_data *pdata;
+        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);
 
@@ -326,9 +328,13 @@ static int __devinit ds1553_rtc_probe(struct platform_device *pdev)
         if (readb(ioaddr + RTC_FLAGS) & RTC_FLAGS_BLF)
                 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, ds1553_rtc_interrupt,
+                if (devm_request_irq(&pdev->dev, pdata->irq,
+                                ds1553_rtc_interrupt,
                                 IRQF_DISABLED, pdev->name, pdev) < 0) {
                         dev_warn(&pdev->dev, "interrupt not available.\n");
                         pdata->irq = 0;
@@ -337,27 +343,13 @@ static int __devinit ds1553_rtc_probe(struct platform_device *pdev)
 
         rtc = rtc_device_register(pdev->name, &pdev->dev,
                                   &ds1553_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;
-        pdata->last_jiffies = jiffies;
-        platform_set_drvdata(pdev, pdata);
+
         ret = sysfs_create_bin_file(&pdev->dev.kobj, &ds1553_nvram_attr);
         if (ret)
-                goto out;
-        return 0;
- out:
-        if (pdata->rtc)
-                rtc_device_unregister(pdata->rtc);
-        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);
+                rtc_device_unregister(rtc);
         return ret;
 }
 
@@ -367,13 +359,8 @@ static int __devexit ds1553_rtc_remove(struct platform_device *pdev)
 
         sysfs_remove_bin_file(&pdev->dev.kobj, &ds1553_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;
 }