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Subject[PATCH] rtc: ds1307: generalise ram size and offset
From
Date
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.

Cc: Wolfram Sang <w.sang@pengutronix.de>
Cc: David Anderson <danders.dev@gmail.com>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Cc: Joakim Tjernlund <Joakim.Tjernlund@transmode.se>
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 2011-10-10 11:22:22.674690998 +1300
+++ b/drivers/rtc/rtc-ds1307.c 2011-11-03 09:13:06.662159569 +1300
@@ -104,10 +104,12 @@ enum ds_type {

struct ds1307 {
u8 offset; /* register's offset */
+ u16 ram_offset;
+ u16 ram_size;
u8 regs[11];
enum ds_type type;
unsigned long flags;
-#define HAS_NVRAM 0 /* bit 0 == sysfs file active */
+#define HAS_RAM 0 /* bit 0 == sysfs file active */
#define HAS_ALARM 1 /* bit 1 == irq claimed */
struct i2c_client *client;
struct rtc_device *rtc;
@@ -119,19 +121,19 @@ struct ds1307 {
};

struct chip_desc {
- unsigned nvram56:1;
+ unsigned ram:1;
unsigned alarm:1;
};

static const struct chip_desc chips[last_ds_type] = {
[ds_1307] = {
- .nvram56 = 1,
+ .ram = 1,
},
[ds_1337] = {
.alarm = 1,
},
[ds_1338] = {
- .nvram56 = 1,
+ .ram = 1,
},
[ds_1339] = {
.alarm = 1,
@@ -139,6 +141,9 @@ static const struct chip_desc chips[last
[ds_3231] = {
.alarm = 1,
},
+ [mcp7941x] = {
+ .ram = 1,
+ },
};

static const struct i2c_device_id ds1307_id[] = {
@@ -543,10 +548,8 @@ static const struct rtc_class_ops ds13xx

/*----------------------------------------------------------------------*/

-#define NVRAM_SIZE 56
-
static ssize_t
-ds1307_nvram_read(struct file *filp, struct kobject *kobj,
+ds1307_ram_read(struct file *filp, struct kobject *kobj,
struct bin_attribute *attr,
char *buf, loff_t off, size_t count)
{
@@ -557,21 +560,22 @@ ds1307_nvram_read(struct file *filp, str
client = kobj_to_i2c_client(kobj);
ds1307 = i2c_get_clientdata(client);

- if (unlikely(off >= NVRAM_SIZE))
+ if (unlikely(off >= ds1307->ram_size))
return 0;
- if ((off + count) > NVRAM_SIZE)
- count = NVRAM_SIZE - off;
+ if ((off + count) > ds1307->ram_size)
+ count = ds1307->ram_size - off;
if (unlikely(!count))
return count;

- result = ds1307->read_block_data(client, 8 + off, count, buf);
+ result = ds1307->read_block_data(client, ds1307->ram_offset + off,
+ count, buf);
if (result < 0)
- dev_err(&client->dev, "%s error %d\n", "nvram read", result);
+ dev_err(&client->dev, "%s error %d\n", "ram read", result);
return result;
}

static ssize_t
-ds1307_nvram_write(struct file *filp, struct kobject *kobj,
+ds1307_ram_write(struct file *filp, struct kobject *kobj,
struct bin_attribute *attr,
char *buf, loff_t off, size_t count)
{
@@ -582,30 +586,30 @@ ds1307_nvram_write(struct file *filp, st
client = kobj_to_i2c_client(kobj);
ds1307 = i2c_get_clientdata(client);

- if (unlikely(off >= NVRAM_SIZE))
+ if (unlikely(off >= ds1307->ram_size))
return -EFBIG;
- if ((off + count) > NVRAM_SIZE)
- count = NVRAM_SIZE - off;
+ if ((off + count) > ds1307->ram_size)
+ count = ds1307->ram_size - off;
if (unlikely(!count))
return count;

- result = ds1307->write_block_data(client, 8 + off, count, buf);
+ result = ds1307->write_block_data(client, ds1307->ram_offset + off,
+ count, buf);
if (result < 0) {
- dev_err(&client->dev, "%s error %d\n", "nvram write", result);
+ dev_err(&client->dev, "%s error %d\n", "ram write", result);
return result;
}
return count;
}

-static struct bin_attribute nvram = {
+static struct bin_attribute ram = {
.attr = {
- .name = "nvram",
+ .name = "ram",
.mode = S_IRUGO | S_IWUSR,
},

- .read = ds1307_nvram_read,
- .write = ds1307_nvram_write,
- .size = NVRAM_SIZE,
+ .read = ds1307_ram_read,
+ .write = ds1307_ram_write,
};

/*----------------------------------------------------------------------*/
@@ -692,6 +696,9 @@ static int __devinit ds1307_probe(struct
break;

case rx_8025:
+ ds1307->ram_size = 64; /* 64 bytes SRAM */
+ ds1307->ram_offset = 0x20;
+
tmp = i2c_smbus_read_i2c_block_data(ds1307->client,
RX8025_REG_CTRL1 << 4 | 0x08, 2, buf);
if (tmp != 2) {
@@ -758,6 +765,8 @@ static int __devinit ds1307_probe(struct
break;
case ds_1388:
ds1307->offset = 1; /* Seconds starts at 1 */
+ ds1307->ram_size = 56; /* 56 bytes NVRAM */
+ ds1307->ram_offset = 8;
break;
default:
break;
@@ -893,11 +902,12 @@ 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 (chip && chip->ram) {
+ ram.size = ds1307->ram_size;
+ err = sysfs_create_bin_file(&client->dev.kobj, &ram);
if (err == 0) {
- set_bit(HAS_NVRAM, &ds1307->flags);
- dev_info(&client->dev, "56 bytes nvram\n");
+ set_bit(HAS_RAM, &ds1307->flags);
+ dev_info(&client->dev, "%zd bytes ram\n", ram.size);
}
}

@@ -919,8 +929,8 @@ static int __devexit ds1307_remove(struc
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_RAM, &ds1307->flags))
+ sysfs_remove_bin_file(&client->dev.kobj, &ram);

rtc_device_unregister(ds1307->rtc);
kfree(ds1307);



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