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    Subject[PATCH 04/20] Input: atmel_mxt_ts - refactor mxt_read/write_reg to take a length
    Date
    The i2c bus requires 5 bytes to do a 1 byte read (1-byte i2c address + 2
    byte offset + 1-byte i2c address + 1 byte data), or 4 bytes to do a
    1-byte write (1 byte i2c address + 2 byte offset + 1 byte data).

    By taking a length with reads and writes, the driver can amortize
    transaction overhead by performing larger transactions where appropriate.

    This patch just sets up the new API. Later patches refactor reads/writes
    to take advantage of the larger transactions.

    Signed-off-by: Daniel Kurtz <djkurtz@chromium.org>
    ---
    drivers/input/touchscreen/atmel_mxt_ts.c | 47 +++++++++++++----------------
    1 files changed, 21 insertions(+), 26 deletions(-)

    diff --git a/drivers/input/touchscreen/atmel_mxt_ts.c b/drivers/input/touchscreen/atmel_mxt_ts.c
    index e18c698..defd4e1 100644
    --- a/drivers/input/touchscreen/atmel_mxt_ts.c
    +++ b/drivers/input/touchscreen/atmel_mxt_ts.c
    @@ -397,8 +397,7 @@ static int mxt_fw_write(struct i2c_client *client,
    return 0;
    }

    -static int __mxt_read_reg(struct i2c_client *client,
    - u16 reg, u16 len, void *val)
    +static int mxt_read_reg(struct i2c_client *client, u16 reg, u16 len, void *val)
    {
    struct i2c_msg xfer[2];
    u8 buf[2];
    @@ -419,28 +418,25 @@ static int __mxt_read_reg(struct i2c_client *client,
    xfer[1].buf = val;

    if (i2c_transfer(client->adapter, xfer, 2) != 2) {
    - dev_err(&client->dev, "%s: i2c transfer failed\n", __func__);
    + dev_err(&client->dev, "%s: i2c read failed\n", __func__);
    return -EIO;
    }

    return 0;
    }

    -static int mxt_read_reg(struct i2c_client *client, u16 reg, u8 *val)
    +static int mxt_write_reg(struct i2c_client *client, u16 reg, u16 len,
    + const void *val)
    {
    - return __mxt_read_reg(client, reg, 1, val);
    -}
    -
    -static int mxt_write_reg(struct i2c_client *client, u16 reg, u8 val)
    -{
    - u8 buf[3];
    + size_t count = 2 + len; /* + 2-byte offset */
    + u8 buf[count];

    buf[0] = reg & 0xff;
    buf[1] = (reg >> 8) & 0xff;
    - buf[2] = val;
    + memcpy(&buf[2], val, len);

    - if (i2c_master_send(client, buf, 3) != 3) {
    - dev_err(&client->dev, "%s: i2c send failed\n", __func__);
    + if (i2c_master_send(client, buf, count) != count) {
    + dev_err(&client->dev, "%s: i2c write failed\n", __func__);
    return -EIO;
    }

    @@ -450,8 +446,7 @@ static int mxt_write_reg(struct i2c_client *client, u16 reg, u8 val)
    static int mxt_read_object_table(struct i2c_client *client,
    u16 reg, u8 *object_buf)
    {
    - return __mxt_read_reg(client, reg, MXT_OBJECT_SIZE,
    - object_buf);
    + return mxt_read_reg(client, reg, MXT_OBJECT_SIZE, object_buf);
    }

    static struct mxt_object *
    @@ -481,8 +476,8 @@ static int mxt_read_message(struct mxt_data *data,
    return -EINVAL;

    reg = object->start_address;
    - return __mxt_read_reg(data->client, reg,
    - sizeof(struct mxt_message), message);
    + return mxt_read_reg(data->client, reg, sizeof(struct mxt_message),
    + message);
    }

    static int mxt_read_object(struct mxt_data *data,
    @@ -496,7 +491,7 @@ static int mxt_read_object(struct mxt_data *data,
    return -EINVAL;

    reg = object->start_address;
    - return __mxt_read_reg(data->client, reg + offset, 1, val);
    + return mxt_read_reg(data->client, reg + offset, 1, val);
    }

    static int mxt_write_object(struct mxt_data *data,
    @@ -510,7 +505,7 @@ static int mxt_write_object(struct mxt_data *data,
    return -EINVAL;

    reg = object->start_address;
    - return mxt_write_reg(data->client, reg + offset, val);
    + return mxt_write_reg(data->client, reg + offset, 1, &val);
    }

    static void mxt_input_report(struct mxt_data *data, int single_id)
    @@ -757,27 +752,27 @@ static int mxt_get_info(struct mxt_data *data)
    int error;
    u8 val;

    - error = mxt_read_reg(client, MXT_FAMILY_ID, &val);
    + error = mxt_read_reg(client, MXT_FAMILY_ID, 1, &val);
    if (error)
    return error;
    info->family_id = val;

    - error = mxt_read_reg(client, MXT_VARIANT_ID, &val);
    + error = mxt_read_reg(client, MXT_VARIANT_ID, 1, &val);
    if (error)
    return error;
    info->variant_id = val;

    - error = mxt_read_reg(client, MXT_VERSION, &val);
    + error = mxt_read_reg(client, MXT_VERSION, 1, &val);
    if (error)
    return error;
    info->version = val;

    - error = mxt_read_reg(client, MXT_BUILD, &val);
    + error = mxt_read_reg(client, MXT_BUILD, 1, &val);
    if (error)
    return error;
    info->build = val;

    - error = mxt_read_reg(client, MXT_OBJECT_NUM, &val);
    + error = mxt_read_reg(client, MXT_OBJECT_NUM, 1, &val);
    if (error)
    return error;
    info->object_num = val;
    @@ -860,12 +855,12 @@ static int mxt_initialize(struct mxt_data *data)
    msleep(MXT_RESET_TIME);

    /* Update matrix size at info struct */
    - error = mxt_read_reg(client, MXT_MATRIX_X_SIZE, &val);
    + error = mxt_read_reg(client, MXT_MATRIX_X_SIZE, 1, &val);
    if (error)
    return error;
    info->matrix_xsize = val;

    - error = mxt_read_reg(client, MXT_MATRIX_Y_SIZE, &val);
    + error = mxt_read_reg(client, MXT_MATRIX_Y_SIZE, 1, &val);
    if (error)
    return error;
    info->matrix_ysize = val;
    --
    1.7.7.3


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