iio:st_pressure: fix sampling gains (bring inline with ABI)

Temperature channels report scaled samples in Celsius although expected as
milli degree Celsius in Documentation/ABI/testing/sysfs-bus-iio.
Gains are not implemented at all for LPS001WP pressure and temperature
channels.

This patch ensures that proper offsets and scales are exposed to userpace
for both pressure and temperature channels.
Also fix a NULL pointer exception when userspace reads content of sysfs
scale attribute when gains are not defined.

Signed-off-by: Gregor Boirie <gregor.boirie@parrot.com>
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

diff --git a/drivers/iio/pressure/st_pressure_core.c b/drivers/iio/pressure/st_pressure_core.c
index 9e9b72a8f18f78fe7d7084710b4854604b7fb0b8..257b58ac67791279ff0c440591bf4908cb7decb8 100644 (file)
--- a/drivers/iio/pressure/st_pressure_core.c
+++ b/drivers/iio/pressure/st_pressure_core.c
@@ -28,15 +28,21 @@
 #include <linux/iio/common/st_sensors.h>
 #include "st_pressure.h"
 
+#define MCELSIUS_PER_CELSIUS                   1000
+
+/* Default pressure sensitivity */
 #define ST_PRESS_LSB_PER_MBAR                  4096UL
 #define ST_PRESS_KPASCAL_NANO_SCALE            (100000000UL / \
                                                 ST_PRESS_LSB_PER_MBAR)
+
+/* Default temperature sensitivity */
 #define ST_PRESS_LSB_PER_CELSIUS               480UL
-#define ST_PRESS_CELSIUS_NANO_SCALE            (1000000000UL / \
-                                                ST_PRESS_LSB_PER_CELSIUS)
+#define ST_PRESS_MILLI_CELSIUS_OFFSET          42500UL
+
 #define ST_PRESS_NUMBER_DATA_CHANNELS          1
 
 /* FULLSCALE */
+#define ST_PRESS_FS_AVL_1100MB                 1100
 #define ST_PRESS_FS_AVL_1260MB                 1260
 
 #define ST_PRESS_1_OUT_XL_ADDR                 0x28
@@ -54,9 +60,6 @@
 #define ST_PRESS_LPS331AP_PW_MASK              0x80
 #define ST_PRESS_LPS331AP_FS_ADDR              0x23
 #define ST_PRESS_LPS331AP_FS_MASK              0x30
-#define ST_PRESS_LPS331AP_FS_AVL_1260_VAL      0x00
-#define ST_PRESS_LPS331AP_FS_AVL_1260_GAIN     ST_PRESS_KPASCAL_NANO_SCALE
-#define ST_PRESS_LPS331AP_FS_AVL_TEMP_GAIN     ST_PRESS_CELSIUS_NANO_SCALE
 #define ST_PRESS_LPS331AP_BDU_ADDR             0x20
 #define ST_PRESS_LPS331AP_BDU_MASK             0x04
 #define ST_PRESS_LPS331AP_DRDY_IRQ_ADDR                0x22
@@ -67,9 +70,14 @@
 #define ST_PRESS_LPS331AP_OD_IRQ_ADDR          0x22
 #define ST_PRESS_LPS331AP_OD_IRQ_MASK          0x40
 #define ST_PRESS_LPS331AP_MULTIREAD_BIT                true
-#define ST_PRESS_LPS331AP_TEMP_OFFSET          42500
 
 /* CUSTOM VALUES FOR LPS001WP SENSOR */
+
+/* LPS001WP pressure resolution */
+#define ST_PRESS_LPS001WP_LSB_PER_MBAR         16UL
+/* LPS001WP temperature resolution */
+#define ST_PRESS_LPS001WP_LSB_PER_CELSIUS      64UL
+
 #define ST_PRESS_LPS001WP_WAI_EXP              0xba
 #define ST_PRESS_LPS001WP_ODR_ADDR             0x20
 #define ST_PRESS_LPS001WP_ODR_MASK             0x30
@@ -78,6 +86,8 @@
 #define ST_PRESS_LPS001WP_ODR_AVL_13HZ_VAL     0x03
 #define ST_PRESS_LPS001WP_PW_ADDR              0x20
 #define ST_PRESS_LPS001WP_PW_MASK              0x40
+#define ST_PRESS_LPS001WP_FS_AVL_PRESS_GAIN \
+       (100000000UL / ST_PRESS_LPS001WP_LSB_PER_MBAR)
 #define ST_PRESS_LPS001WP_BDU_ADDR             0x20
 #define ST_PRESS_LPS001WP_BDU_MASK             0x04
 #define ST_PRESS_LPS001WP_MULTIREAD_BIT                true
@@ -94,11 +104,6 @@
 #define ST_PRESS_LPS25H_ODR_AVL_25HZ_VAL       0x04
 #define ST_PRESS_LPS25H_PW_ADDR                        0x20
 #define ST_PRESS_LPS25H_PW_MASK                        0x80
-#define ST_PRESS_LPS25H_FS_ADDR                        0x00
-#define ST_PRESS_LPS25H_FS_MASK                        0x00
-#define ST_PRESS_LPS25H_FS_AVL_1260_VAL                0x00
-#define ST_PRESS_LPS25H_FS_AVL_1260_GAIN       ST_PRESS_KPASCAL_NANO_SCALE
-#define ST_PRESS_LPS25H_FS_AVL_TEMP_GAIN       ST_PRESS_CELSIUS_NANO_SCALE
 #define ST_PRESS_LPS25H_BDU_ADDR               0x20
 #define ST_PRESS_LPS25H_BDU_MASK               0x04
 #define ST_PRESS_LPS25H_DRDY_IRQ_ADDR          0x23
@@ -109,7 +114,6 @@
 #define ST_PRESS_LPS25H_OD_IRQ_ADDR            0x22
 #define ST_PRESS_LPS25H_OD_IRQ_MASK            0x40
 #define ST_PRESS_LPS25H_MULTIREAD_BIT          true
-#define ST_PRESS_LPS25H_TEMP_OFFSET            42500
 #define ST_PRESS_LPS25H_OUT_XL_ADDR            0x28
 #define ST_TEMP_LPS25H_OUT_L_ADDR              0x2b
 
@@ -161,7 +165,9 @@ static const struct iio_chan_spec st_press_lps001wp_channels[] = {
                        .storagebits = 16,
                        .endianness = IIO_LE,
                },
-               .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
+               .info_mask_separate =
+                       BIT(IIO_CHAN_INFO_RAW) |
+                       BIT(IIO_CHAN_INFO_SCALE),
                .modified = 0,
        },
        {
@@ -177,7 +183,7 @@ static const struct iio_chan_spec st_press_lps001wp_channels[] = {
                },
                .info_mask_separate =
                        BIT(IIO_CHAN_INFO_RAW) |
-                       BIT(IIO_CHAN_INFO_OFFSET),
+                       BIT(IIO_CHAN_INFO_SCALE),
                .modified = 0,
        },
        IIO_CHAN_SOFT_TIMESTAMP(1)
@@ -212,11 +218,14 @@ static const struct st_sensor_settings st_press_sensors_settings[] = {
                        .addr = ST_PRESS_LPS331AP_FS_ADDR,
                        .mask = ST_PRESS_LPS331AP_FS_MASK,
                        .fs_avl = {
+                               /*
+                                * Pressure and temperature sensitivity values
+                                * as defined in table 3 of LPS331AP datasheet.
+                                */
                                [0] = {
                                        .num = ST_PRESS_FS_AVL_1260MB,
-                                       .value = ST_PRESS_LPS331AP_FS_AVL_1260_VAL,
-                                       .gain = ST_PRESS_LPS331AP_FS_AVL_1260_GAIN,
-                                       .gain2 = ST_PRESS_LPS331AP_FS_AVL_TEMP_GAIN,
+                                       .gain = ST_PRESS_KPASCAL_NANO_SCALE,
+                                       .gain2 = ST_PRESS_LSB_PER_CELSIUS,
                                },
                        },
                },
@@ -261,7 +270,17 @@ static const struct st_sensor_settings st_press_sensors_settings[] = {
                        .value_off = ST_SENSORS_DEFAULT_POWER_OFF_VALUE,
                },
                .fs = {
-                       .addr = 0,
+                       .fs_avl = {
+                               /*
+                                * Pressure and temperature resolution values
+                                * as defined in table 3 of LPS001WP datasheet.
+                                */
+                               [0] = {
+                                       .num = ST_PRESS_FS_AVL_1100MB,
+                                       .gain = ST_PRESS_LPS001WP_FS_AVL_PRESS_GAIN,
+                                       .gain2 = ST_PRESS_LPS001WP_LSB_PER_CELSIUS,
+                               },
+                       },
                },
                .bdu = {
                        .addr = ST_PRESS_LPS001WP_BDU_ADDR,
@@ -298,14 +317,15 @@ static const struct st_sensor_settings st_press_sensors_settings[] = {
                        .value_off = ST_SENSORS_DEFAULT_POWER_OFF_VALUE,
                },
                .fs = {
-                       .addr = ST_PRESS_LPS25H_FS_ADDR,
-                       .mask = ST_PRESS_LPS25H_FS_MASK,
                        .fs_avl = {
+                               /*
+                                * Pressure and temperature sensitivity values
+                                * as defined in table 3 of LPS25H datasheet.
+                                */
                                [0] = {
                                        .num = ST_PRESS_FS_AVL_1260MB,
-                                       .value = ST_PRESS_LPS25H_FS_AVL_1260_VAL,
-                                       .gain = ST_PRESS_LPS25H_FS_AVL_1260_GAIN,
-                                       .gain2 = ST_PRESS_LPS25H_FS_AVL_TEMP_GAIN,
+                                       .gain = ST_PRESS_KPASCAL_NANO_SCALE,
+                                       .gain2 = ST_PRESS_LSB_PER_CELSIUS,
                                },
                        },
                },
@@ -364,26 +384,26 @@ static int st_press_read_raw(struct iio_dev *indio_dev,
 
                return IIO_VAL_INT;
        case IIO_CHAN_INFO_SCALE:
-               *val = 0;
-
                switch (ch->type) {
                case IIO_PRESSURE:
+                       *val = 0;
                        *val2 = press_data->current_fullscale->gain;
-                       break;
+                       return IIO_VAL_INT_PLUS_NANO;
                case IIO_TEMP:
+                       *val = MCELSIUS_PER_CELSIUS;
                        *val2 = press_data->current_fullscale->gain2;
-                       break;
+                       return IIO_VAL_FRACTIONAL;
                default:
                        err = -EINVAL;
                        goto read_error;
                }
 
-               return IIO_VAL_INT_PLUS_NANO;
        case IIO_CHAN_INFO_OFFSET:
                switch (ch->type) {
                case IIO_TEMP:
-                       *val = 425;
-                       *val2 = 10;
+                       *val = ST_PRESS_MILLI_CELSIUS_OFFSET *
+                              press_data->current_fullscale->gain2;
+                       *val2 = MCELSIUS_PER_CELSIUS;
                        break;
                default:
                        err = -EINVAL;