rtc: ds1307: generalise ram size and offset

Generalise NVRAM to support RAM with other size and offset, such as the
64 bytes of SRAM on the mcp7941x.

[rdunlap@xenotime.net: fix printk format warning]
Signed-off-by: Austin Boyle <Austin.Boyle@aviatnet.com>
Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>
Signed-off-by: Randy Dunlap <rdunlap@xenotime.net>
Cc: David Anders <danders.dev@gmail.com>
Cc: Alessandro Zummo <alessandro.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/rtc-ds1307.c b/drivers/rtc/rtc-ds1307.c
index 84ab971978cfe0a5173ae02eda53460ceffc6891..cd188ab72f79c7bba15f5c59d055705d2a68e140 100644 (file)
--- a/drivers/rtc/rtc-ds1307.c
+++ b/drivers/rtc/rtc-ds1307.c
@@ -105,6 +105,8 @@ enum ds_type {
 struct ds1307 {
        u8                      offset; /* register's offset */
        u8                      regs[11];
+       u16                     nvram_offset;
+       struct bin_attribute    *nvram;
        enum ds_type            type;
        unsigned long           flags;
 #define HAS_NVRAM      0               /* bit 0 == sysfs file active */
@@ -119,19 +121,22 @@ struct ds1307 {
 };
 
 struct chip_desc {
-       unsigned                nvram56:1;
        unsigned                alarm:1;
+       u16                     nvram_offset;
+       u16                     nvram_size;
 };
 
 static const struct chip_desc chips[last_ds_type] = {
        [ds_1307] = {
-               .nvram56        = 1,
+               .nvram_offset   = 8,
+               .nvram_size     = 56,
        },
        [ds_1337] = {
                .alarm          = 1,
        },
        [ds_1338] = {
-               .nvram56        = 1,
+               .nvram_offset   = 8,
+               .nvram_size     = 56,
        },
        [ds_1339] = {
                .alarm          = 1,
@@ -139,6 +144,11 @@ static const struct chip_desc chips[last_ds_type] = {
        [ds_3231] = {
                .alarm          = 1,
        },
+       [mcp7941x] = {
+               /* this is battery backed SRAM */
+               .nvram_offset   = 0x20,
+               .nvram_size     = 0x40,
+       },
 };
 
 static const struct i2c_device_id ds1307_id[] = {
@@ -543,8 +553,6 @@ static const struct rtc_class_ops ds13xx_rtc_ops = {
 
 /*----------------------------------------------------------------------*/
 
-#define NVRAM_SIZE     56
-
 static ssize_t
 ds1307_nvram_read(struct file *filp, struct kobject *kobj,
                struct bin_attribute *attr,
@@ -557,14 +565,15 @@ ds1307_nvram_read(struct file *filp, struct kobject *kobj,
        client = kobj_to_i2c_client(kobj);
        ds1307 = i2c_get_clientdata(client);
 
-       if (unlikely(off >= NVRAM_SIZE))
+       if (unlikely(off >= ds1307->nvram->size))
                return 0;
-       if ((off + count) > NVRAM_SIZE)
-               count = NVRAM_SIZE - off;
+       if ((off + count) > ds1307->nvram->size)
+               count = ds1307->nvram->size - off;
        if (unlikely(!count))
                return count;
 
-       result = ds1307->read_block_data(client, 8 + off, count, buf);
+       result = ds1307->read_block_data(client, ds1307->nvram_offset + off,
+                                                               count, buf);
        if (result < 0)
                dev_err(&client->dev, "%s error %d\n", "nvram read", result);
        return result;
@@ -582,14 +591,15 @@ ds1307_nvram_write(struct file *filp, struct kobject *kobj,
        client = kobj_to_i2c_client(kobj);
        ds1307 = i2c_get_clientdata(client);
 
-       if (unlikely(off >= NVRAM_SIZE))
+       if (unlikely(off >= ds1307->nvram->size))
                return -EFBIG;
-       if ((off + count) > NVRAM_SIZE)
-               count = NVRAM_SIZE - off;
+       if ((off + count) > ds1307->nvram->size)
+               count = ds1307->nvram->size - off;
        if (unlikely(!count))
                return count;
 
-       result = ds1307->write_block_data(client, 8 + off, count, buf);
+       result = ds1307->write_block_data(client, ds1307->nvram_offset + off,
+                                                               count, buf);
        if (result < 0) {
                dev_err(&client->dev, "%s error %d\n", "nvram write", result);
                return result;
@@ -597,17 +607,6 @@ ds1307_nvram_write(struct file *filp, struct kobject *kobj,
        return count;
 }
 
-static struct bin_attribute nvram = {
-       .attr = {
-               .name   = "nvram",
-               .mode   = S_IRUGO | S_IWUSR,
-       },
-
-       .read   = ds1307_nvram_read,
-       .write  = ds1307_nvram_write,
-       .size   = NVRAM_SIZE,
-};
-
 /*----------------------------------------------------------------------*/
 
 static int __devinit ds1307_probe(struct i2c_client *client,
@@ -894,16 +893,31 @@ read_rtc:
                dev_dbg(&client->dev, "got IRQ %d\n", client->irq);
        }
 
-       if (chip->nvram56) {
-               err = sysfs_create_bin_file(&client->dev.kobj, &nvram);
-               if (err == 0) {
-                       set_bit(HAS_NVRAM, &ds1307->flags);
-                       dev_info(&client->dev, "56 bytes nvram\n");
+       if (chip->nvram_size) {
+               ds1307->nvram = kzalloc(sizeof(struct bin_attribute),
+                                                       GFP_KERNEL);
+               if (!ds1307->nvram) {
+                       err = -ENOMEM;
+                       goto exit_nvram;
+               }
+               ds1307->nvram->attr.name = "nvram";
+               ds1307->nvram->attr.mode = S_IRUGO | S_IWUSR;
+               ds1307->nvram->read = ds1307_nvram_read,
+               ds1307->nvram->write = ds1307_nvram_write,
+               ds1307->nvram->size = chip->nvram_size;
+               ds1307->nvram_offset = chip->nvram_offset;
+               err = sysfs_create_bin_file(&client->dev.kobj, ds1307->nvram);
+               if (err) {
+                       kfree(ds1307->nvram);
+                       goto exit_nvram;
                }
+               set_bit(HAS_NVRAM, &ds1307->flags);
+               dev_info(&client->dev, "%zu bytes nvram\n", ds1307->nvram->size);
        }
 
        return 0;
 
+exit_nvram:
 exit_irq:
        rtc_device_unregister(ds1307->rtc);
 exit_free:
@@ -920,8 +934,10 @@ static int __devexit ds1307_remove(struct i2c_client *client)
                cancel_work_sync(&ds1307->work);
        }
 
-       if (test_and_clear_bit(HAS_NVRAM, &ds1307->flags))
-               sysfs_remove_bin_file(&client->dev.kobj, &nvram);
+       if (test_and_clear_bit(HAS_NVRAM, &ds1307->flags)) {
+               sysfs_remove_bin_file(&client->dev.kobj, ds1307->nvram);
+               kfree(ds1307->nvram);
+       }
 
        rtc_device_unregister(ds1307->rtc);
        kfree(ds1307);