diff --git a/drivers/rtc/rtc-cmos.c b/drivers/rtc/rtc-cmos.c
index 29cf1457ca10f507104a5a54d9fedd88f0544a95..ab455ddb16cf9f053b411d31ab5eeb67d6834e94 100644
--- a/drivers/rtc/rtc-cmos.c
+++ b/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