---

yaml
---
r: 83527
b: refs/heads/master
c: e07e232
h: refs/heads/master
i:
  83525: 3d33568
  83523: 5591dfd
  83519: ecb7806
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 9974b6ea7b85a32f34f824443f47aa501c85ee8f
+refs/heads/master: e07e232cd96ef0092b2bddc72f9b7caf284633cb

trunk/drivers/rtc/rtc-cmos.c

@@ -393,6 +393,80 @@ static const struct rtc_class_ops cmos_rtc_ops = {
 
 /*----------------------------------------------------------------*/
 
+/*
+ * All these chips have at least 64 bytes of address space, shared by
+ * RTC registers and NVRAM.  Most of those bytes of NVRAM are used
+ * by boot firmware.  Modern chips have 128 or 256 bytes.
+ */
+
+#define NVRAM_OFFSET	(RTC_REG_D + 1)
+
+static ssize_t
+cmos_nvram_read(struct kobject *kobj, struct bin_attribute *attr,
+		char *buf, loff_t off, size_t count)
+{
+	int	retval;
+
+	if (unlikely(off >= attr->size))
+		return 0;
+	if ((off + count) > attr->size)
+		count = attr->size - off;
+
+	spin_lock_irq(&rtc_lock);
+	for (retval = 0, off += NVRAM_OFFSET; count--; retval++, off++)
+		*buf++ = CMOS_READ(off);
+	spin_unlock_irq(&rtc_lock);
+
+	return retval;
+}
+
+static ssize_t
+cmos_nvram_write(struct kobject *kobj, struct bin_attribute *attr,
+		char *buf, loff_t off, size_t count)
+{
+	struct cmos_rtc	*cmos;
+	int		retval;
+
+	cmos = dev_get_drvdata(container_of(kobj, struct device, kobj));
+	if (unlikely(off >= attr->size))
+		return -EFBIG;
+	if ((off + count) > attr->size)
+		count = attr->size - off;
+
+	/* NOTE:  on at least PCs and Ataris, the boot firmware uses a
+	 * checksum on part of the NVRAM data.  That's currently ignored
+	 * here.  If userspace is smart enough to know what fields of
+	 * NVRAM to update, updating checksums is also part of its job.
+	 */
+	spin_lock_irq(&rtc_lock);
+	for (retval = 0, off += NVRAM_OFFSET; count--; retval++, off++) {
+		/* don't trash RTC registers */
+		if (off == cmos->day_alrm
+				|| off == cmos->mon_alrm
+				|| off == cmos->century)
+			buf++;
+		else
+			CMOS_WRITE(*buf++, off);
+	}
+	spin_unlock_irq(&rtc_lock);
+
+	return retval;
+}
+
+static struct bin_attribute nvram = {
+	.attr = {
+		.name	= "nvram",
+		.mode	= S_IRUGO | S_IWUSR,
+		.owner	= THIS_MODULE,
+	},
+
+	.read	= cmos_nvram_read,
+	.write	= cmos_nvram_write,
+	/* size gets set up later */
+};
+
+/*----------------------------------------------------------------*/
+
 static struct cmos_rtc	cmos_rtc;
 
 static irqreturn_t cmos_interrupt(int irq, void *p)
@@ -412,11 +486,9 @@ static irqreturn_t cmos_interrupt(int irq, void *p)
 }
 
 #ifdef	CONFIG_PNP
-#define	is_pnp()	1
 #define	INITSECTION
 
 #else
-#define	is_pnp()	0
 #define	INITSECTION	__init
 #endif
 
@@ -426,6 +498,7 @@ cmos_do_probe(struct device *dev, struct resource *ports, int rtc_irq)
 	struct cmos_rtc_board_info	*info = dev->platform_data;
 	int				retval = 0;
 	unsigned char			rtc_control;
+	unsigned			address_space;
 
 	/* there can be only one ... */
 	if (cmos_rtc.dev)
@@ -450,15 +523,36 @@ cmos_do_probe(struct device *dev, struct resource *ports, int rtc_irq)
 	cmos_rtc.irq = rtc_irq;
 	cmos_rtc.iomem = ports;
 
+	/* Heuristic to deduce NVRAM size ... do what the legacy NVRAM
+	 * driver did, but don't reject unknown configs.   Old hardware
+	 * won't address 128 bytes, and for now we ignore the way newer
+	 * chips can address 256 bytes (using two more i/o ports).
+	 */
+#if	defined(CONFIG_ATARI)
+	address_space = 64;
+#elif defined(__i386__) || defined(__x86_64__) || defined(__arm__)
+	address_space = 128;
+#else
+#warning Assuming 128 bytes of RTC+NVRAM address space, not 64 bytes.
+	address_space = 128;
+#endif
+
 	/* For ACPI systems extension info comes from the FADT.  On others,
 	 * board specific setup provides it as appropriate.  Systems where
 	 * the alarm IRQ isn't automatically a wakeup IRQ (like ACPI, and
 	 * some almost-clones) can provide hooks to make that behave.
+	 *
+	 * Note that ACPI doesn't preclude putting these registers into
+	 * "extended" areas of the chip, including some that we won't yet
+	 * expect CMOS_READ and friends to handle.
 	 */
 	if (info) {
-		cmos_rtc.day_alrm = info->rtc_day_alarm;
-		cmos_rtc.mon_alrm = info->rtc_mon_alarm;
-		cmos_rtc.century = info->rtc_century;
+		if (info->rtc_day_alarm && info->rtc_day_alarm < 128)
+			cmos_rtc.day_alrm = info->rtc_day_alarm;
+		if (info->rtc_mon_alarm && info->rtc_mon_alarm < 128)
+			cmos_rtc.mon_alrm = info->rtc_mon_alarm;
+		if (info->rtc_century && info->rtc_century < 128)
+			cmos_rtc.century = info->rtc_century;
 
 		if (info->wake_on && info->wake_off) {
 			cmos_rtc.wake_on = info->wake_on;
@@ -518,10 +612,13 @@ cmos_do_probe(struct device *dev, struct resource *ports, int rtc_irq)
 		goto cleanup1;
 	}
 
-	/* REVISIT optionally make 50 or 114 bytes NVRAM available,
-	 * like rtc-ds1553, rtc-ds1742 ... this will often include
-	 * registers for century, and day/month alarm.
-	 */
+	/* export at least the first block of NVRAM */
+	nvram.size = address_space - NVRAM_OFFSET;
+	retval = sysfs_create_bin_file(&dev->kobj, &nvram);
+	if (retval < 0) {
+		dev_dbg(dev, "can't create nvram file? %d\n", retval);
+		goto cleanup2;
+	}
 
 	pr_info("%s: alarms up to one %s%s\n",
 			cmos_rtc.rtc->dev.bus_id,
@@ -536,6 +633,9 @@ cmos_do_probe(struct device *dev, struct resource *ports, int rtc_irq)
 
 	return 0;
 
+cleanup2:
+	if (is_valid_irq(rtc_irq))
+		free_irq(rtc_irq, cmos_rtc.rtc);
 cleanup1:
 	cmos_rtc.dev = NULL;
 	rtc_device_unregister(cmos_rtc.rtc);
@@ -563,6 +663,8 @@ static void __exit cmos_do_remove(struct device *dev)
 
 	cmos_do_shutdown();
 
+	sysfs_remove_bin_file(&dev->kobj, &nvram);
+
 	if (is_valid_irq(cmos->irq))
 		free_irq(cmos->irq, cmos->rtc);
 
@@ -659,9 +761,12 @@ static int cmos_resume(struct device *dev)
 
 /*----------------------------------------------------------------*/
 
-/* The "CMOS" RTC normally lives on the platform_bus.  On ACPI systems,
- * the device node will always be created as a PNPACPI device.  Plus
- * pre-ACPI PCs probably list it in the PNPBIOS tables.
+/* On non-x86 systems, a "CMOS" RTC lives most naturally on platform_bus.
+ * ACPI systems always list these as PNPACPI devices, and pre-ACPI PCs
+ * probably list them in similar PNPBIOS tables; so PNP is more common.
+ *
+ * We don't use legacy "poke at the hardware" probing.  Ancient PCs that
+ * predate even PNPBIOS should set up platform_bus devices.
  */
 
 #ifdef	CONFIG_PNP