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SubjectRe: [PATCH v2] rtc: ds1307: generalise ram size and offset
On Thu, Nov 03, 2011 at 12:33:54PM +1300, Austin Boyle wrote:
> 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.

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

>
> 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 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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