Re: [PATCH v2] rtc: ds1307: generalise ram size and offset

[Wolfram Sang]

On Thu, Nov 03, 2011 at 12:33:54PM +1300, Austin Boyle wrote:
> From: Austin Boyle <Austin.Boyle@xxxxxxxxxxxx>
> 
> This patch generalises NVRAM to support RAM with other size and offset, such
> as the 64 bytes of SRAM on the mcp7941x.

Thanks! This made the patch much more readable, so I saw another optimization.
And one question.

> 
> Cc: Wolfram Sang <w.sang@xxxxxxxxxxxxxx>
> Cc: David Anderson <danders.dev@xxxxxxxxx>
> Cc: Alessandro Zummo <a.zummo@xxxxxxxxxxxx>
> Cc: Joakim Tjernlund <Joakim.Tjernlund@xxxxxxxxxxxx>
> Signed-off-by: Austin Boyle <Austin.Boyle@xxxxxxxxxxxx>
> ---
> 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 12:17:40.777642801 +1300
> @@ -104,6 +104,8 @@ enum ds_type {
>  
>  struct ds1307 {
>  	u8			offset; /* register's offset */
> +	u16			nvram_offset;
> +	u16			nvram_size;
>  	u8			regs[11];
>  	enum ds_type		type;
>  	unsigned long		flags;
> @@ -119,19 +121,19 @@ struct ds1307 {
>  };
>  
>  struct chip_desc {
> -	unsigned		nvram56:1;
> +	unsigned		nvram:1;

What about removing this field...

>  	unsigned		alarm:1;
>  };
>  
>  static const struct chip_desc chips[last_ds_type] = {
>  	[ds_1307] = {
> -		.nvram56	= 1,
> +		.nvram		= 1,
>  	},
>  	[ds_1337] = {
>  		.alarm		= 1,
>  	},
>  	[ds_1338] = {
> -		.nvram56	= 1,
> +		.nvram		= 1,
>  	},
>  	[ds_1339] = {
>  		.alarm		= 1,
> @@ -139,6 +141,9 @@ static const struct chip_desc chips[last
>  	[ds_3231] = {
>  		.alarm		= 1,
>  	},
> +	[mcp7941x] = {
> +		.nvram		= 1,
> +	},
>  };
>  
>  static const struct i2c_device_id ds1307_id[] = {
> @@ -543,8 +548,6 @@ 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,
> @@ -557,14 +560,15 @@ 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->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 +586,15 @@ 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->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;
> @@ -605,7 +610,6 @@ static struct bin_attribute nvram = {
>  
>  	.read	= ds1307_nvram_read,
>  	.write	= ds1307_nvram_write,
> -	.size	= NVRAM_SIZE,
>  };
>  
>  /*----------------------------------------------------------------------*/
> @@ -692,6 +696,9 @@ static int __devinit ds1307_probe(struct
>  		break;
>  
>  	case rx_8025:
> +		ds1307->nvram_size = 64; /* 64 bytes SRAM */
> +		ds1307->nvram_offset = 0x20;
> +

Question: Why are you adding this code here and not to the mcp7941x related
code?

>  		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->nvram_size = 56; /* 56 bytes NVRAM */
> +		ds1307->nvram_offset = 8;

Is this the right place to enable it for the 1307/1338?

>  		break;
>  	default:
>  		break;
> @@ -893,11 +902,12 @@ read_rtc:
>  		dev_dbg(&client->dev, "got IRQ %d\n", client->irq);
>  	}
>  
> -	if (chip && chip->nvram56) {
> +	if (chip && chip->nvram) {

If we removed the nvram field above, then we could simply use
ds1307->nvram_size here. If that turns out to be too messy to set up, we could
also put nvram_size and nvram_offset to the chip_desc instead.

> +		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, "%zd bytes nvram\n", nvram.size);
>  		}
>  	}
>  
> 

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

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