1 files changed, 48 insertions, 46 deletions

diff --git a/drivers/iio/pressure/bmp280-core.c b/drivers/iio/pressure/bmp280-core.c
index f25df7f..6943688 100644
--- a/drivers/iio/pressure/bmp280-core.c
+++ b/drivers/iio/pressure/bmp280-core.c
@@ -31,9 +31,30 @@
 #include <linux/irq.h> /* For irq_get_irq_data() */
 #include <linux/completion.h>
 #include <linux/pm_runtime.h>
+#include <linux/random.h>
 
 #include "bmp280.h"
 
+/*
+ * These enums are used for indexing into the array of calibration
+ * coefficients for BMP180.
+ */
+enum { AC1, AC2, AC3, AC4, AC5, AC6, B1, B2, MB, MC, MD };
+
+struct bmp180_calib {
+	s16 AC1;
+	s16 AC2;
+	s16 AC3;
+	u16 AC4;
+	u16 AC5;
+	u16 AC6;
+	s16 B1;
+	s16 B2;
+	s16 MB;
+	s16 MC;
+	s16 MD;
+};
+
 struct bmp280_data {
 	struct device *dev;
 	struct mutex lock;
@@ -41,6 +62,7 @@ struct bmp280_data {
 	struct completion done;
 	bool use_eoc;
 	const struct bmp280_chip_info *chip_info;
+	struct bmp180_calib calib;
 	struct regulator *vddd;
 	struct regulator *vdda;
 	unsigned int start_up_time; /* in milliseconds */
@@ -663,26 +685,6 @@ static int bmp180_read_adc_temp(struct bmp280_data *data, int *val)
 	return 0;
 }
 
-/*
- * These enums are used for indexing into the array of calibration
- * coefficients for BMP180.
- */
-enum { AC1, AC2, AC3, AC4, AC5, AC6, B1, B2, MB, MC, MD };
-
-struct bmp180_calib {
-	s16 AC1;
-	s16 AC2;
-	s16 AC3;
-	u16 AC4;
-	u16 AC5;
-	u16 AC6;
-	s16 B1;
-	s16 B2;
-	s16 MB;
-	s16 MC;
-	s16 MD;
-};
-
 static int bmp180_read_calib(struct bmp280_data *data,
 			     struct bmp180_calib *calib)
 {
@@ -702,6 +704,9 @@ static int bmp180_read_calib(struct bmp280_data *data,
 			return -EIO;
 	}
 
+	/* Toss the calibration data into the entropy pool */
+	add_device_randomness(buf, sizeof(buf));
+
 	calib->AC1 = be16_to_cpu(buf[AC1]);
 	calib->AC2 = be16_to_cpu(buf[AC2]);
 	calib->AC3 = be16_to_cpu(buf[AC3]);
@@ -725,19 +730,11 @@ static int bmp180_read_calib(struct bmp280_data *data,
  */
 static s32 bmp180_compensate_temp(struct bmp280_data *data, s32 adc_temp)
 {
-	int ret;
 	s32 x1, x2;
-	struct bmp180_calib calib;
+	struct bmp180_calib *calib = &data->calib;
 
-	ret = bmp180_read_calib(data, &calib);
-	if (ret < 0) {
-		dev_err(data->dev,
-			"failed to read calibration coefficients\n");
-		return ret;
-	}
-
-	x1 = ((adc_temp - calib.AC6) * calib.AC5) >> 15;
-	x2 = (calib.MC << 11) / (x1 + calib.MD);
+	x1 = ((adc_temp - calib->AC6) * calib->AC5) >> 15;
+	x2 = (calib->MC << 11) / (x1 + calib->MD);
 	data->t_fine = x1 + x2;
 
 	return (data->t_fine + 8) >> 4;
@@ -792,29 +789,21 @@ static int bmp180_read_adc_press(struct bmp280_data *data, int *val)
  */
 static u32 bmp180_compensate_press(struct bmp280_data *data, s32 adc_press)
 {
-	int ret;
 	s32 x1, x2, x3, p;
 	s32 b3, b6;
 	u32 b4, b7;
 	s32 oss = data->oversampling_press;
-	struct bmp180_calib calib;
-
-	ret = bmp180_read_calib(data, &calib);
-	if (ret < 0) {
-		dev_err(data->dev,
-			"failed to read calibration coefficients\n");
-		return ret;
-	}
+	struct bmp180_calib *calib = &data->calib;
 
 	b6 = data->t_fine - 4000;
-	x1 = (calib.B2 * (b6 * b6 >> 12)) >> 11;
-	x2 = calib.AC2 * b6 >> 11;
+	x1 = (calib->B2 * (b6 * b6 >> 12)) >> 11;
+	x2 = calib->AC2 * b6 >> 11;
 	x3 = x1 + x2;
-	b3 = ((((s32)calib.AC1 * 4 + x3) << oss) + 2) / 4;
-	x1 = calib.AC3 * b6 >> 13;
-	x2 = (calib.B1 * ((b6 * b6) >> 12)) >> 16;
+	b3 = ((((s32)calib->AC1 * 4 + x3) << oss) + 2) / 4;
+	x1 = calib->AC3 * b6 >> 13;
+	x2 = (calib->B1 * ((b6 * b6) >> 12)) >> 16;
 	x3 = (x1 + x2 + 2) >> 2;
-	b4 = calib.AC4 * (u32)(x3 + 32768) >> 15;
+	b4 = calib->AC4 * (u32)(x3 + 32768) >> 15;
 	b7 = ((u32)adc_press - b3) * (50000 >> oss);
 	if (b7 < 0x80000000)
 		p = (b7 * 2) / b4;
@@ -1018,6 +1007,19 @@ int bmp280_common_probe(struct device *dev,
 	dev_set_drvdata(dev, indio_dev);
 
 	/*
+	 * The BMP085 and BMP180 has calibration in an E2PROM, read it out
+	 * at probe time. It will not change.
+	 */
+	if (chip_id  == BMP180_CHIP_ID) {
+		ret = bmp180_read_calib(data, &data->calib);
+		if (ret < 0) {
+			dev_err(data->dev,
+				"failed to read calibration coefficients\n");
+			goto out_disable_vdda;
+		}
+	}
+
+	/*
 	 * Attempt to grab an optional EOC IRQ - only the BMP085 has this
 	 * however as it happens, the BMP085 shares the chip ID of BMP180
 	 * so we look for an IRQ if we have that.