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SubjectRe: [PATCH v3] rtc: ds1307: generalise ram size and offset
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Date
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 21af5f7bd6
rtc: ds1307: simplify irq setup code 8c63e03627
rtc: ds1307: refactor chip_desc table e246db081d
rtc: add initial support for mcp7941x parts e69bba2d3a

--- 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,
@@ -893,16 +892,31 @@ read_rtc:
dev_dbg(&client->dev, "got IRQ %d\n", client->irq);
}

- if (chip && 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 && 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:
@@ -919,8 +933,10 @@ 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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