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    SubjectRe: [PATCH v3] rtc: ds1307: generalise ram size and offset
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    Hi Wolfram,

    Thanks for reviewing the patch.

    > I think the stuff related to 'offset' should be in a separate patch with
    > specific commit-msg.
    Agreed. I will submit a separate patch after this one.

    ---

    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;
    + u16 nvram_size;
    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;
    @@ -605,7 +615,6 @@ static struct bin_attribute nvram = {

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

    /*----------------------------------------------------------------------*/
    @@ -638,7 +647,12 @@ static int __devinit ds1307_probe(struct i2c_client *client,

    ds1307->client = client;
    ds1307->type = id->driver_data;
    - ds1307->offset = 0;
    + if (chip) {
    + if (chip->nvram_size)
    + ds1307->nvram_size = chip->nvram_size;
    + if (chip->nvram_offset)
    + ds1307->nvram_offset = chip->nvram_offset;
    + }

    buf = ds1307->regs;
    if (i2c_check_functionality(adapter, I2C_FUNC_SMBUS_I2C_BLOCK)) {
    @@ -893,11 +907,12 @@ read_rtc:
    dev_dbg(&client->dev, "got IRQ %d\n", client->irq);
    }

    - if (chip && chip->nvram56) {
    + if (chip && chip->nvram_size) {
    + 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);
    }
    }



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