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Subject[PATCH v4] rtc: ds1307: generalise ram size and offset
From
Date
Hi,

Wolfram: I saw the comments on your previous patch that chip will never be NULL
so I have removed the check from this patch also. This version is against
your most recent tree.

Andrew: Is it best for you if Wolfram adds this to his tree and then you
can pull the patches it depends on at the same time? The version of this
patch that has currently been added to -mm has some problems.

---
rtc: ds1307: generalise ram size and offset

From: Austin Boyle <Austin.Boyle@aviatnet.com>

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

Signed-off-by: Austin Boyle <Austin.Boyle@aviatnet.com>
---
this patch is based on Wolfram Sang's tree:
git://git.pengutronix.de/git/wsa/linux-2.6.git ds1307
patch depends on:
rtc: ds1307: comment and format cleanup 38f0a1072f
rtc: ds1307: simplify irq setup code f5af1f6ffe
rtc: ds1307: refactor chip_desc table c0920a32b7

--- 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, "%d 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);


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