Re: [PATCH 09/12] hwmon: lis3: use block read to access data registers

Jonathan Cameron
2010-10-22T16:20:03Z

On 10/22/10 12:57, Samu Onkalo wrote:
> Add optional blockread function to interface driver. If available
> the chip driver uses it for data register access. For 12 bit device
> it reads 6 bytes to get 3*16bit data. For 8 bit device it reads out
> 5 bytes since every second byte is dummy.
> This optimizes bus usage and reduces number of operations and
> interrupts needed for one data update.
>
All good now.
> Signed-off-by: Samu Onkalo <samu.p.onkalo@nokia.com>
Acked-by: Jonathan Cameron <jic23@cam.ac.uk>
> ---
> drivers/hwmon/lis3lv02d.c | 21 ++++++++++++++++++---
> drivers/hwmon/lis3lv02d.h | 1 +
> drivers/hwmon/lis3lv02d_i2c.c | 13 +++++++++++++
> include/linux/lis3lv02d.h | 1 +
> 4 files changed, 33 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/hwmon/lis3lv02d.c b/drivers/hwmon/lis3lv02d.c
> index 7555091..9fd946c 100644
> --- a/drivers/hwmon/lis3lv02d.c
> +++ b/drivers/hwmon/lis3lv02d.c
> @@ -130,9 +130,24 @@ static void lis3lv02d_get_xyz(struct lis3lv02d *lis3, int *x, int *y, int *z)
> int position[3];
> int i;
>
> - position[0] = lis3->read_data(lis3, OUTX);
> - position[1] = lis3->read_data(lis3, OUTY);
> - position[2] = lis3->read_data(lis3, OUTZ);
> + if (lis3->blkread) {
> + if (lis3_dev.whoami == WAI_12B) {
> + u16 data[3];
> + lis3->blkread(lis3, OUTX_L, 6, (u8 *)data);
> + for (i = 0; i < 3; i++)
> + position[i] = (s16)le16_to_cpu(data[i]);
> + } else {
> + u8 data[5];
> + /* Data: x, dummy, y, dummy, z */
> + lis3->blkread(lis3, OUTX, 5, data);
> + for (i = 0; i < 3; i++)
> + position[i] = (s8)data[i * 2];
> + }
> + } else {
> + position[0] = lis3->read_data(lis3, OUTX);
> + position[1] = lis3->read_data(lis3, OUTY);
> + position[2] = lis3->read_data(lis3, OUTZ);
> + }
>
> for (i = 0; i < 3; i++)
> position[i] = (position[i] * lis3->scale) / LIS3_ACCURACY;
> diff --git a/drivers/hwmon/lis3lv02d.h b/drivers/hwmon/lis3lv02d.h
> index 2ac27b9..d3cb662 100644
> --- a/drivers/hwmon/lis3lv02d.h
> +++ b/drivers/hwmon/lis3lv02d.h
> @@ -225,6 +225,7 @@ struct lis3lv02d {
> int (*init) (struct lis3lv02d *lis3);
> int (*write) (struct lis3lv02d *lis3, int reg, u8 val);
> int (*read) (struct lis3lv02d *lis3, int reg, u8 *ret);
> + int (*blkread) (struct lis3lv02d *lis3, int reg, int len, u8 *ret);
> int (*reg_ctrl) (struct lis3lv02d *lis3, bool state);
>
> int *odrs; /* Supported output data rates */
> diff --git a/drivers/hwmon/lis3lv02d_i2c.c b/drivers/hwmon/lis3lv02d_i2c.c
> index 36171bf..61c109b 100644
> --- a/drivers/hwmon/lis3lv02d_i2c.c
> +++ b/drivers/hwmon/lis3lv02d_i2c.c
> @@ -66,6 +66,14 @@ static inline s32 lis3_i2c_read(struct lis3lv02d *lis3, int reg, u8 *v)
> return 0;
> }
>
> +static inline s32 lis3_i2c_blockread(struct lis3lv02d *lis3, int reg, int len,
> + u8 *v)
> +{
> + struct i2c_client *c = lis3->bus_priv;
> + reg |= (1 << 7); /* 7th bit enables address auto incrementation */
> + return i2c_smbus_read_i2c_block_data(c, reg, len, v);
> +}
> +
> static int lis3_i2c_init(struct lis3lv02d *lis3)
> {
> u8 reg;
> @@ -103,6 +111,11 @@ static int __devinit lis3lv02d_i2c_probe(struct i2c_client *client,
> if (pdata->driver_features & LIS3_USE_REGULATOR_CTRL)
> lis3_dev.reg_ctrl = lis3_reg_ctrl;
>
> + if ((pdata->driver_features & LIS3_USE_BLOCK_READ) &&
> + (i2c_check_functionality(client->adapter,
> + I2C_FUNC_SMBUS_I2C_BLOCK)))
> + lis3_dev.blkread = lis3_i2c_blockread;
> +
> if (pdata->axis_x)
> lis3lv02d_axis_map.x = pdata->axis_x;
>
> diff --git a/include/linux/lis3lv02d.h b/include/linux/lis3lv02d.h
> index 18d578f..c949612 100644
> --- a/include/linux/lis3lv02d.h
> +++ b/include/linux/lis3lv02d.h
> @@ -68,6 +68,7 @@ struct lis3lv02d_platform_data {
> s8 axis_y;
> s8 axis_z;
> #define LIS3_USE_REGULATOR_CTRL 0x01
> +#define LIS3_USE_BLOCK_READ 0x02
> u16 driver_features;
> int default_rate;
> int (*setup_resources)(void);