Patchwork Re: [PATCH 2.6.39-rc7] RTC: rtc-ds1307 EEPROM support for ds1388 chip

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Submitter Austin Boyle
Date July 31, 2011, 10:30 p.m.
Message ID <1312151457.24642.5747.camel@pc786-ubu.gnet.global.vpn>
Download mbox | patch
Permalink /patch/107648/
State New
Headers show

Comments

Austin Boyle - July 31, 2011, 10:30 p.m.
Hi Andrew,

Thank you very much for your feedback. I have corrected the issues you raised as follows. 
The updated patch has been appended.

On Fri, 2011-07-22 at 14:54 -0700, Andrew Morton wrote:
> On Tue, 14 Jun 2011 16:14:57 +1200
> Austin Boyle <Austin.Boyle@aviatnet.com> wrote:
> 
> > On Mon, 2011-05-23 at 17:18 +1200, Austin Boyle wrote:
> > > This is my patch which extends the NVRAM access functions in the DS1307
> > > driver to support the 512 bytes of EEPROM on the DS1388 chip. Could you
> > > please review the patch? If there are any problems with the way I have
> > > implemented this or suggested improvements I will gladly modify. Thanks!
> > 
> > This is an updated version of the patch which prints the correct NVRAM
> > size at init. Could someone please give me some feedback?
> > 
> > [PATCH 3.0-rc3] RTC: rtc-ds1307: EEPROM support for ds1388 chip
> > 
> > This patch adds support for different sized NVRAM, such as
> > the 512 bytes of EEPROM on the DS1388 chip.
> 
> The patch is wordwrapped - please fix your email client.
Done.
> 
> The patch makes rather a mess of a decent-looking driver.  Please use
> scripts/checkpatch.pl and review its report.
> 
Fixed all errors and warnings.
> >
> > ...
> >
> > @@ -540,18 +545,39 @@ ds1307_nvram_read(struct file *filp, str
> >  	struct i2c_client	*client;
> >  	struct ds1307		*ds1307;
> >  	int			result;
> > +	unsigned int		addr = 0;
> >  
> >  	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);
> > +	if (ds1307->nvram_offset < 0xff) {	/* ds1307, ds1338 */
> > +		result = ds1307->read_block_data(client, ds1307->nvram_offset + off,
> > count, buf);
> > +	} else	{	/* ds1388 */
> > +		if ((off <= 0x00ff) && (off + count > 0x00ff))	{	/* read spans two
> > blocks */
> > +			client = ds1307->client[1];		/* first block */
> > +			addr = (unsigned int)off;
> > +			result = ds1307->read_block_data(client, addr, (0x100-addr), buf);
> 
> Ignores a possible error return value?
Added check.
> 
> > +			client = ds1307->client[2];		/* second block */
> > +			result += ds1307->read_block_data(client, 0x00, (count+addr-0x100),
> > (buf+0x100-addr));
> > +
> > +		} else { 	/* read spans one blocks */
> > +			if (off <= 0x00ff)	{
> > +				client = ds1307->client[1];
> > +				addr = (unsigned int)off;
> > +			} else if (off <= 0x0200)	{
> > +				client = ds1307->client[2];
> > +				addr = (unsigned int)off - 0x100;
> > +			}
> > +			result = ds1307->read_block_data(client, addr, count, buf);
> > +		}
> > +	}
> >  	if (result < 0)
> >  		dev_err(&client->dev, "%s error %d\n", "nvram read", result);
> >  	return result;
> > @@ -565,18 +591,40 @@ ds1307_nvram_write(struct file *filp, st
> >  	struct i2c_client	*client;
> >  	struct ds1307		*ds1307;
> >  	int			result;
> > +	unsigned int		addr = 0;
> >  
> >  	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);
> > +	if (ds1307->nvram_offset < 0xff) {	/* ds1307, ds1338 */
> > +		result = ds1307->write_block_data(client, ds1307->nvram_offset + off,
> > count, buf);
> > +	} else	{	/* ds1388 */
> > +		if ((off <= 0x00ff) && ((off + count) > 0x00ff))	{  /* read spans two
> > blocks */
> > +			client = ds1307->client[1];		/* first block */
> > +			addr = (unsigned int)off;
> > +			result = ds1307->write_block_data(client, addr, (0x100-addr), buf);
> 
> Error checking?
Added.
> 
> > +			client = ds1307->client[2];		/* second block */
> > +			result = ds1307->write_block_data(client, 0x00, (addr+count-0x100),
> > (buf+0x100-addr));
> > +
> > +		} else { /* Device address/offset translation */
> > +			dev_dbg(&client->dev, "Write spans one block\n");
> > +			if (off <= 0x00ff)	{
> 
> A single space before the {
Fixed.
> 
> > +				client = ds1307->client[1];
> > +				addr = (unsigned int)off;
> > +			} else if (off <= 0x0200)	{
> 
> ditto
Fixed.
> 
> > +				client = ds1307->client[2];
> > +				addr = (unsigned int)off - 0x100;
> > +			}
> > +			result = ds1307->write_block_data(client, addr, count, buf);
> > +		}
> > +	}
> >  	if (result < 0) {
> >  		dev_err(&client->dev, "%s error %d\n", "nvram write", result);
> >  		return result;
> >
> > ...
> >
> > @@ -866,16 +923,35 @@ read_rtc:
> >  		dev_dbg(&client->dev, "got IRQ %d\n", client->irq);
> >  	}
> >  
> > -	if (chip->nvram56) {
> > +	if (chip->nvram) {
> > +		nvram.size = ds1307->nvram_size;
> >  		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");
> > +			dev_info(&client->dev, "%d bytes nvram\n", nvram.size);
> > +		}
> > +	}
> > +
> > +	/* use dummy devices for multiple address chips */
> > +	for (i = 1; i < ds1307->num_addrs; i++) {
> > +		ds1307->client[i] = i2c_new_dummy(client->adapter, client->addr + i);
> > +		if (!ds1307->client[i]) {
> > +			dev_err(&client->dev, "address 0x%02x unavailable\n",
> > +					client->addr + i);
> > +			err = -EADDRINUSE;
> 
> EADDRINUSE is a networking error code.  Returning that from an
> rtc-related operation might mislead the operator.
Fixed. Now returns -EBUSY, the same as rtc-s35390a does.
> 
> 
> > +			goto err_clients;
> >  		}
> > +		i2c_set_clientdata(ds1307->client[i], ds1307);
> >  	}
> >  
> >  	return 0;
> >  
> > +err_clients:
> > +	for (i = 1; i < ds1307->num_addrs; i++)	{
> > +		if (ds1307->client[i])	{
> > +			i2c_unregister_device(ds1307->client[i]);
> > +		}
> 
> We normally omit braces around a single statement.
Fixed.
> 
> The `if (ds1307->client[i])' test should be unneeded anyway - just
> unregister client[1] though client[i - 1].
> 
> Why isn't client[0] used here btw?
> 
This loop is only unregistering the dummy i2c devices that were created. The same behaviour as rtc-s35390a.

---

[PATCH 3.0] RTC: EEPROM support for DS1388

This patch adds support for different sized NVRAM, such as
the 512 bytes of EEPROM on the DS1388 chip.

Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Cc: Joakim Tjernlund <Joakim.Tjernlund@transmode.se>
Signed-off-by: Austin Boyle <austin.boyle@aviatnet.com>
---
Andrew Morton - Sept. 23, 2011, 11:04 p.m.
On Mon, 1 Aug 2011 10:30:57 +1200
Austin Boyle <Austin.Boyle@Aviatnet.com> wrote:

> [PATCH 3.0] RTC: EEPROM support for DS1388
> 
> This patch adds support for different sized NVRAM, such as
> the 512 bytes of EEPROM on the DS1388 chip.

This patch is causing problems in today's linux-next, with x86_64 allmodconfig:

drivers/rtc/rtc-ds1307.c: In function 'ds1307_probe':
drivers/rtc/rtc-ds1307.c:796: warning: passing argument 1 of 'i2c_smbus_read_i2c_block_data' from incompatible pointer type
include/linux/i2c.h:98: note: expected 'const struct i2c_client *' but argument is of type 'struct i2c_client **'
drivers/rtc/rtc-ds1307.c:949: warning: format '%d' expects type 'int', but argument 3 has type 'size_t'

Please take a look?  You'll need %z for the printk warning.
Wolfram Sang - Sept. 24, 2011, 6:53 a.m.
On Fri, Sep 23, 2011 at 04:04:45PM -0700, Andrew Morton wrote:
> On Mon, 1 Aug 2011 10:30:57 +1200
> Austin Boyle <Austin.Boyle@Aviatnet.com> wrote:
> 
> > [PATCH 3.0] RTC: EEPROM support for DS1388
> > 
> > This patch adds support for different sized NVRAM, such as
> > the 512 bytes of EEPROM on the DS1388 chip.
> 
> This patch is causing problems in today's linux-next, with x86_64 allmodconfig:

Sorry, I missed the patch so far. The whole approach is not correct.

The EEPROM uses a different I2C slave address (0x69+0x6a) than the RTC (0x68).
So, you should be able to use the ds1307-driver on address 0x68 (maybe with
minor modifications, didn't check that) and the eeprom part using the
at24-driver on address 0x69, selecting the 24c02-type. Despite saving redundant
code, at24 handles peculiarities of EEPROMs much better. Can you please report
if that works for you?

Regards,

   Wolfram
David Anders - Sept. 28, 2011, 4:38 p.m.
Wolfram,

i am continuing to add support for the MCP7941x series which has
64bytes of NVRAM instead of the default 54 bytes currently in the
DS1307 driver.

is there an existing plan to make the NVRAM support more generic, i.e.
similar to the patch posted here, or do we need to start batting
around ideas as RFC?

thanks
Dave


On Sep 24, 1:53 am, Wolfram Sang <w.s...@pengutronix.de> wrote:
> On Fri, Sep 23, 2011 at 04:04:45PM -0700, Andrew Morton wrote:
> > On Mon, 1 Aug 2011 10:30:57 +1200
> > Austin Boyle <Austin.Bo...@Aviatnet.com> wrote:
>
> > > [PATCH 3.0] RTC: EEPROM support for DS1388
>
> > > This patch adds support for different sized NVRAM, such as
> > > the 512 bytes of EEPROM on the DS1388 chip.
>
> > This patch is causing problems in today's linux-next, with x86_64 allmodconfig:
>
> Sorry, I missed the patch so far. The whole approach is not correct.
>
> The EEPROM uses a different I2C slave address (0x69+0x6a) than the RTC (0x68).
> So, you should be able to use the ds1307-driver on address 0x68 (maybe with
> minor modifications, didn't check that) and the eeprom part using the
> at24-driver on address 0x69, selecting the 24c02-type. Despite saving redundant
> code, at24 handles peculiarities of EEPROMs much better. Can you please report
> if that works for you?
>
> Regards,
>
>    Wolfram
>
> --
> Pengutronix e.K.                           | Wolfram Sang                |
> Industrial Linux Solutions                 |http://www.pengutronix.de/ |
>
>  signature.asc
> < 1KViewDownload
Wolfram Sang - Sept. 28, 2011, 5:08 p.m.
> is there an existing plan to make the NVRAM support more generic, i.e.
> similar to the patch posted here, or do we need to start batting
> around ideas as RFC?

IMO the patch posted here is too complex handling multiple I2C addresses and
such. A simpler approach, only introducing nvram_size and nvram_offset (or
nvram_start and nvram_end; whatever you prefer) never leaving the current
address seems like a good enhancement, though. And that's probably all that is
needed for now.

(BTW why are you sometimes writing with a nickname? I was a bit confused first)

Thanks,

   Wolfram
David Anders - Sept. 28, 2011, 6:25 p.m.
Wolfram,

On Wed, Sep 28, 2011 at 12:08 PM, Wolfram Sang <w.sang@pengutronix.de>wrote:

>
> > is there an existing plan to make the NVRAM support more generic, i.e.
> > similar to the patch posted here, or do we need to start batting
> > around ideas as RFC?
>
> IMO the patch posted here is too complex handling multiple I2C addresses
> and
> such. A simpler approach, only introducing nvram_size and nvram_offset (or
> nvram_start and nvram_end; whatever you prefer) never leaving the current
> address seems like a good enhancement, though. And that's probably all that
> is
> needed for now.
>
>
agreed. i'll pull the nvram bits from this patch and do some testing.


> (BTW why are you sometimes writing with a nickname? I was a bit confused
> first)
>
>
i noticed this as well. for some reason when i used the google groups web
view to post it uses my nick, whereas when i use my gmail account it shows
up my full name. i plan to avoid using the web interface for google groups
posts in the future.



> Thanks,
>
>   Wolfram
>
> --
> Pengutronix e.K.                           | Wolfram Sang                |
> Industrial Linux Solutions                 | http://www.pengutronix.de/  |
>

thanks
Dave

Patch

diff -upNr a/drivers/rtc/rtc-ds1307.c b/drivers/rtc/rtc-ds1307.c
--- a/drivers/rtc/rtc-ds1307.c	2011-06-29 11:59:29.275414436 +1200
+++ b/drivers/rtc/rtc-ds1307.c	2011-08-01 10:17:42.415351158 +1200
@@ -95,15 +95,19 @@  enum ds_type {
 #	define RX8025_BIT_VDET		0x40
 #	define RX8025_BIT_XST		0x20
 
+#define DS1307_MAX_NUM_ADDRS	3
 
 struct ds1307 {
 	u8			offset; /* register's offset */
+	u16			nvram_size;
+	u16			nvram_offset;
+	u8			num_addrs;
 	u8			regs[11];
 	enum ds_type		type;
 	unsigned long		flags;
 #define HAS_NVRAM	0		/* bit 0 == sysfs file active */
 #define HAS_ALARM	1		/* bit 1 == irq claimed */
-	struct i2c_client	*client;
+	struct i2c_client	*client[DS1307_MAX_NUM_ADDRS];
 	struct rtc_device	*rtc;
 	struct work_struct	work;
 	s32 (*read_block_data)(const struct i2c_client *client, u8 command,
@@ -113,23 +117,26 @@  struct ds1307 {
 };
 
 struct chip_desc {
-	unsigned		nvram56:1;
+	unsigned		nvram:1;
 	unsigned		alarm:1;
 };
 
 static const struct chip_desc chips[] = {
 [ds_1307] = {
-	.nvram56	= 1,
+	.nvram		= 1,
 },
 [ds_1337] = {
 	.alarm		= 1,
 },
 [ds_1338] = {
-	.nvram56	= 1,
+	.nvram		= 1,
 },
 [ds_1339] = {
 	.alarm		= 1,
 },
+[ds_1388] = {
+	.nvram		= 1,
+},
 [ds_1340] = {
 },
 [ds_3231] = {
@@ -249,7 +256,7 @@  static void ds1307_work(struct work_stru
 	int			stat, control;
 
 	ds1307 = container_of(work, struct ds1307, work);
-	client = ds1307->client;
+	client = ds1307->client[0];
 	lock = &ds1307->rtc->ops_lock;
 
 	mutex_lock(lock);
@@ -295,7 +302,7 @@  static int ds1307_get_time(struct device
 	int		tmp;
 
 	/* read the RTC date and time registers all at once */
-	tmp = ds1307->read_block_data(ds1307->client,
+	tmp = ds1307->read_block_data(ds1307->client[0],
 		ds1307->offset, 7, ds1307->regs);
 	if (tmp != 7) {
 		dev_err(dev, "%s error %d\n", "read", tmp);
@@ -373,7 +380,7 @@  static int ds1307_set_time(struct device
 		"write", buf[0], buf[1], buf[2], buf[3],
 		buf[4], buf[5], buf[6]);
 
-	result = ds1307->write_block_data(ds1307->client,
+	result = ds1307->write_block_data(ds1307->client[0],
 		ds1307->offset, 7, buf);
 	if (result < 0) {
 		dev_err(dev, "%s error %d\n", "write", result);
@@ -531,8 +538,6 @@  static const struct rtc_class_ops ds13xx
 
 /*----------------------------------------------------------------------*/
 
-#define NVRAM_SIZE	56
-
 static ssize_t
 ds1307_nvram_read(struct file *filp, struct kobject *kobj,
 		struct bin_attribute *attr,
@@ -541,19 +546,49 @@  ds1307_nvram_read(struct file *filp, str
 	struct i2c_client	*client;
 	struct ds1307		*ds1307;
 	int			result;
+	unsigned int		addr = 0;
 
 	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);
-	if (result < 0)
+	if (ds1307->nvram_offset < 0xff) {
+		result = ds1307->read_block_data(client,
+						ds1307->nvram_offset + off,
+						count, buf);
+	} else {
+		/* read spans two blocks */
+		if ((off <= 0x00ff) && (off + count > 0x00ff)) {
+			client = ds1307->client[1];
+			addr = (unsigned int)off;
+			result = ds1307->read_block_data(client, addr,
+							(0x100-addr), buf);
+			if (result < 0)
+				goto err;
+			client = ds1307->client[2];
+			result = ds1307->read_block_data(client, 0x00,
+							(count+addr-0x100),
+							(buf+0x100-addr));
+		/* read spans one blocks */
+		} else {
+			if (off <= 0x00ff) {
+				client = ds1307->client[1];
+				addr = (unsigned int)off;
+			} else if (off <= 0x0200) {
+				client = ds1307->client[2];
+				addr = (unsigned int)off - 0x100;
+			}
+			result = ds1307->read_block_data(client, addr,
+							count, buf);
+		}
+	}
+err:	if (result < 0)
 		dev_err(&client->dev, "%s error %d\n", "nvram read", result);
 	return result;
 }
@@ -566,19 +601,49 @@  ds1307_nvram_write(struct file *filp, st
 	struct i2c_client	*client;
 	struct ds1307		*ds1307;
 	int			result;
+	unsigned int		addr = 0;
 
 	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);
-	if (result < 0) {
+	if (ds1307->nvram_offset < 0xff) {
+		result = ds1307->write_block_data(client,
+						ds1307->nvram_offset + off,
+						count, buf);
+	} else {
+		/* read spans two blocks */
+		if ((off <= 0x00ff) && ((off + count) > 0x00ff)) {
+			client = ds1307->client[1];
+			addr = (unsigned int)off;
+			result = ds1307->write_block_data(client, addr,
+							(0x100-addr), buf);
+			if (result < 0)
+				goto err;
+			client = ds1307->client[2];
+			result = ds1307->write_block_data(client, 0x00,
+							(addr+count-0x100),
+							(buf+0x100-addr));
+		/* read spans one blocks */
+		} else {
+			if (off <= 0x00ff) {
+				client = ds1307->client[1];
+				addr = (unsigned int)off;
+			} else if (off <= 0x0200) {
+				client = ds1307->client[2];
+				addr = (unsigned int)off - 0x100;
+			}
+			result = ds1307->write_block_data(client, addr,
+							count, buf);
+		}
+	}
+err:	if (result < 0) {
 		dev_err(&client->dev, "%s error %d\n", "nvram write", result);
 		return result;
 	}
@@ -593,7 +658,6 @@  static struct bin_attribute nvram = {
 
 	.read	= ds1307_nvram_read,
 	.write	= ds1307_nvram_write,
-	.size	= NVRAM_SIZE,
 };
 
 /*----------------------------------------------------------------------*/
@@ -606,6 +670,7 @@  static int __devinit ds1307_probe(struct
 	struct ds1307		*ds1307;
 	int			err = -ENODEV;
 	int			tmp;
+	int			i;
 	const struct chip_desc	*chip = &chips[id->driver_data];
 	struct i2c_adapter	*adapter = to_i2c_adapter(client->dev.parent);
 	int			want_irq = false;
@@ -625,9 +690,10 @@  static int __devinit ds1307_probe(struct
 
 	i2c_set_clientdata(client, ds1307);
 
-	ds1307->client	= client;
+	ds1307->client[0] = client;
 	ds1307->type	= id->driver_data;
 	ds1307->offset	= 0;
+	ds1307->num_addrs = 1;
 
 	buf = ds1307->regs;
 	if (i2c_check_functionality(adapter, I2C_FUNC_SMBUS_I2C_BLOCK)) {
@@ -643,12 +709,12 @@  static int __devinit ds1307_probe(struct
 	case ds_1339:
 	case ds_3231:
 		/* has IRQ? */
-		if (ds1307->client->irq > 0 && chip->alarm) {
+		if (client->irq > 0 && chip->alarm) {
 			INIT_WORK(&ds1307->work, ds1307_work);
 			want_irq = true;
 		}
 		/* get registers that the "rtc" read below won't read... */
-		tmp = ds1307->read_block_data(ds1307->client,
+		tmp = ds1307->read_block_data(client,
 				DS1337_REG_CONTROL, 2, buf);
 		if (tmp != 2) {
 			pr_debug("read error %d\n", tmp);
@@ -682,7 +748,7 @@  static int __devinit ds1307_probe(struct
 		break;
 
 	case rx_8025:
-		tmp = i2c_smbus_read_i2c_block_data(ds1307->client,
+		tmp = i2c_smbus_read_i2c_block_data(client,
 				RX8025_REG_CTRL1 << 4 | 0x08, 2, buf);
 		if (tmp != 2) {
 			pr_debug("read error %d\n", tmp);
@@ -748,6 +814,14 @@  static int __devinit ds1307_probe(struct
 		break;
 	case ds_1388:
 		ds1307->offset = 1; /* Seconds starts at 1 */
+		ds1307->num_addrs = 3;	/* uses 3 I2C addrs */
+		ds1307->nvram_size = 512; /* 512 bytes EEPROM */
+		ds1307->nvram_offset = 0xff;
+		break;
+	case ds_1307:
+	case ds_1338:
+		ds1307->nvram_size = 56; /* 56 bytes NVRAM */
+		ds1307->nvram_offset = 8;
 		break;
 	default:
 		break;
@@ -755,7 +829,7 @@  static int __devinit ds1307_probe(struct
 
 read_rtc:
 	/* read RTC registers */
-	tmp = ds1307->read_block_data(ds1307->client, ds1307->offset, 8, buf);
+	tmp = ds1307->read_block_data(client, ds1307->offset, 8, buf);
 	if (tmp != 8) {
 		pr_debug("read error %d\n", tmp);
 		err = -EIO;
@@ -867,16 +941,34 @@  read_rtc:
 		dev_dbg(&client->dev, "got IRQ %d\n", client->irq);
 	}
 
-	if (chip->nvram56) {
+	if (chip->nvram) {
+		nvram.size = ds1307->nvram_size;
 		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");
+			dev_info(&client->dev, "%d bytes nvram\n", nvram.size);
+		}
+	}
+
+	/* use dummy devices for multiple address chips */
+	for (i = 1; i < ds1307->num_addrs; i++) {
+		ds1307->client[i] = i2c_new_dummy(client->adapter,
+						client->addr + i);
+		if (!ds1307->client[i]) {
+			dev_err(&client->dev, "Address %02x unavailable\n",
+					client->addr + i);
+			err = -EBUSY;
+			goto exit_dummy;
 		}
+		i2c_set_clientdata(ds1307->client[i], ds1307);
 	}
 
 	return 0;
 
+exit_dummy:
+	for (i = 1; i < ds1307->num_addrs; i++)
+		if (ds1307->client[i])
+			i2c_unregister_device(ds1307->client[i]);
 exit_irq:
 	rtc_device_unregister(ds1307->rtc);
 exit_free: