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

Samu Onkalo
2010-10-22T11:57:31Z

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.

Signed-off-by: Samu Onkalo <samu.p.onkalo@nokia.com>
---
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);
--
1.6.0.4