rtc: rtc-ds1742 nvram attribute fix

The RTC driver for ds1742 / ds1743 uses a static nvram attribute.  This
patch replaces this static attribute with one nvram attribute for each
ds174x registered.

The nvram size is not the same for all types of ds174x.  The nvram size is
accessible as the file size of the nvram attribute in sysfs.  With only a
single nvram attribute, this file size will be incorrect if more than one
type of ds174x is present on a system.  See the comment in the removed
code below.

This patch have been tested with linux-2.6.28 and linux-2.6.29-rc5/6 on a
custom board with one ds1743.

Signed-off-by: Torsten Ertbjerg Rasmussen <ertbjerg@gmail.com>
Signed-off-by: Alessandro Zummo <a.zummo@towertech.it>
Cc: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
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>

drivers/rtc/rtc-ds1742.c

@@ -57,6 +57,7 @@ struct rtc_plat_data {
 	size_t size;
 	resource_size_t baseaddr;
 	unsigned long last_jiffies;
+	struct bin_attribute nvram_attr;
 };
 
 static int ds1742_rtc_set_time(struct device *dev, struct rtc_time *tm)
@@ -157,18 +158,6 @@ static ssize_t ds1742_nvram_write(struct kobject *kobj,
 	return count;
 }
 
-static struct bin_attribute ds1742_nvram_attr = {
-	.attr = {
-		.name = "nvram",
-		.mode = S_IRUGO | S_IWUSR,
-	},
-	.read = ds1742_nvram_read,
-	.write = ds1742_nvram_write,
-	/* REVISIT: size in sysfs won't match actual size... if it's
-	 * not a constant, each RTC should have its own attribute.
-	 */
-};
-
 static int __devinit ds1742_rtc_probe(struct platform_device *pdev)
 {
 	struct rtc_device *rtc;
@@ -199,6 +188,12 @@ static int __devinit ds1742_rtc_probe(struct platform_device *pdev)
 	pdata->size_nvram = pdata->size - RTC_SIZE;
 	pdata->ioaddr_rtc = ioaddr + pdata->size_nvram;
 
+	pdata->nvram_attr.attr.name = "nvram";
+	pdata->nvram_attr.attr.mode = S_IRUGO | S_IWUSR;
+	pdata->nvram_attr.read = ds1742_nvram_read;
+	pdata->nvram_attr.write = ds1742_nvram_write;
+	pdata->nvram_attr.size = pdata->size_nvram;
+
 	/* turn RTC on if it was not on */
 	ioaddr = pdata->ioaddr_rtc;
 	sec = readb(ioaddr + RTC_SECONDS);
@@ -221,11 +216,13 @@ static int __devinit ds1742_rtc_probe(struct platform_device *pdev)
 	pdata->rtc = rtc;
 	pdata->last_jiffies = jiffies;
 	platform_set_drvdata(pdev, pdata);
-	ds1742_nvram_attr.size = max(ds1742_nvram_attr.size,
-				     pdata->size_nvram);
-	ret = sysfs_create_bin_file(&pdev->dev.kobj, &ds1742_nvram_attr);
-	if (ret)
+
+	ret = sysfs_create_bin_file(&pdev->dev.kobj, &pdata->nvram_attr);
+	if (ret) {
+		dev_err(&pdev->dev, "creating nvram file in sysfs failed\n");
 		goto out;
+	}
+
 	return 0;
  out:
 	if (pdata->rtc)
@@ -242,7 +239,7 @@ static int __devexit ds1742_rtc_remove(struct platform_device *pdev)
 {
 	struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
 
-	sysfs_remove_bin_file(&pdev->dev.kobj, &ds1742_nvram_attr);
+	sysfs_remove_bin_file(&pdev->dev.kobj, &pdata->nvram_attr);
 	rtc_device_unregister(pdata->rtc);
 	iounmap(pdata->ioaddr_nvram);
 	release_mem_region(pdata->baseaddr, pdata->size);