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Subject[PATCH 03/16 v2] 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>
Reviewed-by: Joonyoung Shim <jy0922.shim@samsung.com>
---
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 15ae6fd..971f9dc 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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