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 (file)
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -135,8 +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/rtc-ds1307.c b/drivers/rtc/rtc-ds1307.c
index db6f3f0..bc1c7fe 100644 (file)
--- 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;