rtc-ds1307 exports NVRAM
Export the NVRAM on DS1307 and DS1338 chips, like several of the
other drivers do for such combination RTC-and-NVRAM chips.
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Acked-by: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index 7958635..e5cdc02 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -135,8 +135,8 @@
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/rtc-ds1307.c b/drivers/rtc/rtc-ds1307.c
index db6f3f0..bc1c7fe 100644
--- a/drivers/rtc/rtc-ds1307.c
+++ b/drivers/rtc/rtc-ds1307.c
@@ -89,6 +89,7 @@
struct ds1307 {
u8 reg_addr;
+ bool has_nvram;
u8 regs[8];
enum ds_type type;
struct i2c_msg msg[2];
@@ -242,6 +243,87 @@
.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 @@
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 @@
{
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;