7 files changed, 108 insertions, 9 deletions

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index cbde770eb121..e5cdc0294aaa 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -36,7 +36,9 @@ config RTC_HCTOSYS_DEVICE
         help
           The RTC device that will be used to (re)initialize the system
           clock, usually rtc0.  Initialization is done when the system
-          starts up, and when it resumes from a low power state.
+          starts up, and when it resumes from a low power state.  This
+          device should record time in UTC, since the kernel won't do
+          timezone correction.
 
           The driver for this RTC device must be loaded before late_initcall
           functions run, so it must usually be statically linked.
@@ -133,8 +135,8 @@ config RTC_DRV_DS1307
 
           The first seven registers on these chips hold an RTC, and other
           registers may add features such as NVRAM, a trickle charger for
-          the RTC/NVRAM backup power, and alarms.  This driver may not
-          expose all those available chip features.
+          the RTC/NVRAM backup power, and alarms.  NVRAM is visible in
+          sysfs, but other chip features may not be available.
 
           This driver can also be built as a module. If so, the module
           will be called rtc-ds1307.
diff --git a/drivers/rtc/hctosys.c b/drivers/rtc/hctosys.c
index 178527252c6a..33c0e98243ee 100644
--- a/drivers/rtc/hctosys.c
+++ b/drivers/rtc/hctosys.c
@@ -47,8 +47,8 @@ static int __init rtc_hctosys(void)
                         do_settimeofday(&tv);
 
                         dev_info(rtc->dev.parent,
-                                "setting the system clock to "
-                                "%d-%02d-%02d %02d:%02d:%02d (%u)\n",
+                                "setting system clock to "
+                                "%d-%02d-%02d %02d:%02d:%02d UTC (%u)\n",
                                 tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday,
                                 tm.tm_hour, tm.tm_min, tm.tm_sec,
                                 (unsigned int) tv.tv_sec);
diff --git a/drivers/rtc/rtc-ds1307.c b/drivers/rtc/rtc-ds1307.c
index db6f3f0d8982..bc1c7fe94ad3 100644
--- a/drivers/rtc/rtc-ds1307.c
+++ b/drivers/rtc/rtc-ds1307.c
@@ -89,6 +89,7 @@ enum ds_type {
 
 struct ds1307 {
         u8                      reg_addr;
+        bool                    has_nvram;
         u8                      regs[8];
         enum ds_type            type;
         struct i2c_msg          msg[2];
@@ -242,6 +243,87 @@ static const struct rtc_class_ops ds13xx_rtc_ops = {
         .set_time       = ds1307_set_time,
 };
 
+/*----------------------------------------------------------------------*/
+
+#define NVRAM_SIZE      56
+
+static ssize_t
+ds1307_nvram_read(struct kobject *kobj, struct bin_attribute *attr,
+                char *buf, loff_t off, size_t count)
+{
+        struct i2c_client       *client;
+        struct ds1307           *ds1307;
+        struct i2c_msg          msg[2];
+        int                     result;
+
+        client = to_i2c_client(container_of(kobj, struct device, kobj));
+        ds1307 = i2c_get_clientdata(client);
+
+        if (unlikely(off >= NVRAM_SIZE))
+                return 0;
+        if ((off + count) > NVRAM_SIZE)
+                count = NVRAM_SIZE - off;
+        if (unlikely(!count))
+                return count;
+
+        msg[0].addr = client->addr;
+        msg[0].flags = 0;
+        msg[0].len = 1;
+        msg[0].buf = buf;
+
+        buf[0] = 8 + off;
+
+        msg[1].addr = client->addr;
+        msg[1].flags = I2C_M_RD;
+        msg[1].len = count;
+        msg[1].buf = buf;
+
+        result = i2c_transfer(to_i2c_adapter(client->dev.parent), msg, 2);
+        if (result != 2) {
+                dev_err(&client->dev, "%s error %d\n", "nvram read", result);
+                return -EIO;
+        }
+        return count;
+}
+
+static ssize_t
+ds1307_nvram_write(struct kobject *kobj, struct bin_attribute *attr,
+                char *buf, loff_t off, size_t count)
+{
+        struct i2c_client       *client;
+        u8                      buffer[NVRAM_SIZE + 1];
+        int                     ret;
+
+        client = to_i2c_client(container_of(kobj, struct device, kobj));
+
+        if (unlikely(off >= NVRAM_SIZE))
+                return -EFBIG;
+        if ((off + count) > NVRAM_SIZE)
+                count = NVRAM_SIZE - off;
+        if (unlikely(!count))
+                return count;
+
+        buffer[0] = 8 + off;
+        memcpy(buffer + 1, buf, count);
+
+        ret = i2c_master_send(client, buffer, count + 1);
+        return (ret < 0) ? ret : (ret - 1);
+}
+
+static struct bin_attribute nvram = {
+        .attr = {
+                .name   = "nvram",
+                .mode   = S_IRUGO | S_IWUSR,
+                .owner  = THIS_MODULE,
+        },
+
+        .read   = ds1307_nvram_read,
+        .write  = ds1307_nvram_write,
+        .size   = NVRAM_SIZE,
+};
+
+/*----------------------------------------------------------------------*/
+
 static struct i2c_driver ds1307_driver;
 
 static int __devinit ds1307_probe(struct i2c_client *client)
@@ -413,6 +495,14 @@ read_rtc:
                 goto exit_free;
         }
 
+        if (chip->nvram56) {
+                err = sysfs_create_bin_file(&client->dev.kobj, &nvram);
+                if (err == 0) {
+                        ds1307->has_nvram = true;
+                        dev_info(&client->dev, "56 bytes nvram\n");
+                }
+        }
+
         return 0;
 
 exit_bad:
@@ -432,6 +522,9 @@ static int __devexit ds1307_remove(struct i2c_client *client)
 {
         struct ds1307   *ds1307 = i2c_get_clientdata(client);
 
+        if (ds1307->has_nvram)
+                sysfs_remove_bin_file(&client->dev.kobj, &nvram);
+
         rtc_device_unregister(ds1307->rtc);
         kfree(ds1307);
         return 0;
diff --git a/drivers/rtc/rtc-ds1553.c b/drivers/rtc/rtc-ds1553.c
index bb53c09bad16..d9e848dcd450 100644
--- a/drivers/rtc/rtc-ds1553.c
+++ b/drivers/rtc/rtc-ds1553.c
@@ -291,7 +291,7 @@ static ssize_t ds1553_nvram_write(struct kobject *kobj,
 static struct bin_attribute ds1553_nvram_attr = {
         .attr = {
                 .name = "nvram",
-                .mode = S_IRUGO | S_IWUGO,
+                .mode = S_IRUGO | S_IWUSR,
         },
         .size = RTC_OFFSET,
         .read = ds1553_nvram_read,
diff --git a/drivers/rtc/rtc-ds1742.c b/drivers/rtc/rtc-ds1742.c
index c535b78698e2..2e73f0b183b2 100644
--- a/drivers/rtc/rtc-ds1742.c
+++ b/drivers/rtc/rtc-ds1742.c
@@ -160,10 +160,13 @@ static ssize_t ds1742_nvram_write(struct kobject *kobj,
 static struct bin_attribute ds1742_nvram_attr = {
         .attr = {
                 .name = "nvram",
-                .mode = S_IRUGO | S_IWUGO,
+                .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)
diff --git a/drivers/rtc/rtc-m48t59.c b/drivers/rtc/rtc-m48t59.c
index 2bad1637330a..cd0bbc0e8038 100644
--- a/drivers/rtc/rtc-m48t59.c
+++ b/drivers/rtc/rtc-m48t59.c
@@ -353,11 +353,12 @@ static ssize_t m48t59_nvram_write(struct kobject *kobj,
 static struct bin_attribute m48t59_nvram_attr = {
         .attr = {
                 .name = "nvram",
-                .mode = S_IRUGO | S_IWUGO,
+                .mode = S_IRUGO | S_IWUSR,
                 .owner = THIS_MODULE,
         },
         .read = m48t59_nvram_read,
         .write = m48t59_nvram_write,
+        .size = M48T59_NVRAM_SIZE,
 };
 
 static int __devinit m48t59_rtc_probe(struct platform_device *pdev)
diff --git a/drivers/rtc/rtc-stk17ta8.c b/drivers/rtc/rtc-stk17ta8.c
index 8288b6b2bf2b..a265da7c6ff8 100644
--- a/drivers/rtc/rtc-stk17ta8.c
+++ b/drivers/rtc/rtc-stk17ta8.c
@@ -291,7 +291,7 @@ static ssize_t stk17ta8_nvram_write(struct kobject *kobj,
 static struct bin_attribute stk17ta8_nvram_attr = {
         .attr = {
                 .name = "nvram",
-                .mode = S_IRUGO | S_IWUGO,
+                .mode = S_IRUGO | S_IWUSR,
                 .owner = THIS_MODULE,
         },
         .size = RTC_OFFSET,