1 files changed, 63 insertions, 7 deletions

diff --git a/drivers/rtc/rtc-cmos.c b/drivers/rtc/rtc-cmos.c
index 963ad0b6a4e9..f1695d7fa0fa 100644
--- a/drivers/rtc/rtc-cmos.c
+++ b/drivers/rtc/rtc-cmos.c
@@ -143,6 +143,43 @@ static inline int hpet_unregister_irq_handler(irq_handler_t handler)
 
 /*----------------------------------------------------------------*/
 
+#ifdef RTC_PORT
+
+/* Most newer x86 systems have two register banks, the first used
+ * for RTC and NVRAM and the second only for NVRAM.  Caller must
+ * own rtc_lock ... and we won't worry about access during NMI.
+ */
+#define can_bank2       true
+
+static inline unsigned char cmos_read_bank2(unsigned char addr)
+{
+        outb(addr, RTC_PORT(2));
+        return inb(RTC_PORT(3));
+}
+
+static inline void cmos_write_bank2(unsigned char val, unsigned char addr)
+{
+        outb(addr, RTC_PORT(2));
+        outb(val, RTC_PORT(2));
+}
+
+#else
+
+#define can_bank2       false
+
+static inline unsigned char cmos_read_bank2(unsigned char addr)
+{
+        return 0;
+}
+
+static inline void cmos_write_bank2(unsigned char val, unsigned char addr)
+{
+}
+
+#endif
+
+/*----------------------------------------------------------------*/
+
 static int cmos_read_time(struct device *dev, struct rtc_time *t)
 {
         /* REVISIT:  if the clock has a "century" register, use
@@ -491,12 +528,21 @@ cmos_nvram_read(struct kobject *kobj, struct bin_attribute *attr,
 
         if (unlikely(off >= attr->size))
                 return 0;
+        if (unlikely(off < 0))
+                return -EINVAL;
         if ((off + count) > attr->size)
                 count = attr->size - off;
 
+        off += NVRAM_OFFSET;
         spin_lock_irq(&rtc_lock);
-        for (retval = 0, off += NVRAM_OFFSET; count--; retval++, off++)
-                *buf++ = CMOS_READ(off);
+        for (retval = 0; count; count--, off++, retval++) {
+                if (off < 128)
+                        *buf++ = CMOS_READ(off);
+                else if (can_bank2)
+                        *buf++ = cmos_read_bank2(off);
+                else
+                        break;
+        }
         spin_unlock_irq(&rtc_lock);
 
         return retval;
@@ -512,6 +558,8 @@ cmos_nvram_write(struct kobject *kobj, struct bin_attribute *attr,
         cmos = dev_get_drvdata(container_of(kobj, struct device, kobj));
         if (unlikely(off >= attr->size))
                 return -EFBIG;
+        if (unlikely(off < 0))
+                return -EINVAL;
         if ((off + count) > attr->size)
                 count = attr->size - off;
 
@@ -520,15 +568,20 @@ cmos_nvram_write(struct kobject *kobj, struct bin_attribute *attr,
          * here.  If userspace is smart enough to know what fields of
          * NVRAM to update, updating checksums is also part of its job.
          */
+        off += NVRAM_OFFSET;
         spin_lock_irq(&rtc_lock);
-        for (retval = 0, off += NVRAM_OFFSET; count--; retval++, off++) {
+        for (retval = 0; count; count--, off++, retval++) {
                 /* don't trash RTC registers */
                 if (off == cmos->day_alrm
                                 || off == cmos->mon_alrm
                                 || off == cmos->century)
                         buf++;
-                else
+                else if (off < 128)
                         CMOS_WRITE(*buf++, off);
+                else if (can_bank2)
+                        cmos_write_bank2(*buf++, off);
+                else
+                        break;
         }
         spin_unlock_irq(&rtc_lock);
 
@@ -631,8 +684,8 @@ cmos_do_probe(struct device *dev, struct resource *ports, int rtc_irq)
 
         /* 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).
+         * won't address 128 bytes.  Newer chips have multiple banks,
+         * though they may not be listed in one I/O resource.
          */
 #if     defined(CONFIG_ATARI)
         address_space = 64;
@@ -642,6 +695,8 @@ cmos_do_probe(struct device *dev, struct resource *ports, int rtc_irq)
 #warning Assuming 128 bytes of RTC+NVRAM address space, not 64 bytes.
         address_space = 128;
 #endif
+        if (can_bank2 && ports->end > (ports->start + 1))
+                address_space = 256;
 
         /* For ACPI systems extension info comes from the FADT.  On others,
          * board specific setup provides it as appropriate.  Systems where
@@ -740,7 +795,7 @@ cmos_do_probe(struct device *dev, struct resource *ports, int rtc_irq)
                 goto cleanup2;
         }
 
-        pr_info("%s: alarms up to one %s%s%s\n",
+        pr_info("%s: alarms up to one %s%s, %zd bytes nvram, %s irqs\n",
                         cmos_rtc.rtc->dev.bus_id,
                         is_valid_irq(rtc_irq)
                                 ?  (cmos_rtc.mon_alrm
@@ -749,6 +804,7 @@ cmos_do_probe(struct device *dev, struct resource *ports, int rtc_irq)
                                                 ? "month" : "day"))
                                 : "no",
                         cmos_rtc.century ? ", y3k" : "",
+                        nvram.size,
                         is_hpet_enabled() ? ", hpet irqs" : "");
 
         return 0;