linux-kernel - [PATCH 4.4 11/32] iio: bmg160: reset chip when probing

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20170410163840.706501305@linuxfoundation.org>
Date:   Mon, 10 Apr 2017 18:39:01 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Quentin Schulz <quentin.schulz@...e-electrons.com>,
        Jonathan Cameron <jic23@...nel.org>
Subject: [PATCH 4.4 11/32] iio: bmg160: reset chip when probing

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Quentin Schulz <quentin.schulz@...e-electrons.com>

commit 4bdc9029685ac03be50b320b29691766d2326c2b upstream.

The gyroscope chip might need to be reset to be used.

Without the chip being reset, the driver stopped at the first
regmap_read (to get the CHIP_ID) and failed to probe.

The datasheet of the gyroscope says that a minimum wait of 30ms after
the reset has to be done.

This patch has been checked on a BMX055 and the datasheet of the BMG160
and the BMI055 give the same reset register and bits.

Signed-off-by: Quentin Schulz <quentin.schulz@...e-electrons.com>
Signed-off-by: Jonathan Cameron <jic23@...nel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/iio/gyro/bmg160_core.c |   12 ++++++++++++
 1 file changed, 12 insertions(+)

--- a/drivers/iio/gyro/bmg160_core.c
+++ b/drivers/iio/gyro/bmg160_core.c
@@ -28,6 +28,7 @@
 #include <linux/iio/trigger_consumer.h>
 #include <linux/iio/triggered_buffer.h>
 #include <linux/regmap.h>
+#include <linux/delay.h>
 #include "bmg160.h"
 
 #define BMG160_IRQ_NAME		"bmg160_event"
@@ -53,6 +54,9 @@
 #define BMG160_NO_FILTER		0
 #define BMG160_DEF_BW			100
 
+#define BMG160_GYRO_REG_RESET		0x14
+#define BMG160_GYRO_RESET_VAL		0xb6
+
 #define BMG160_REG_INT_MAP_0		0x17
 #define BMG160_INT_MAP_0_BIT_ANY	BIT(1)
 
@@ -186,6 +190,14 @@ static int bmg160_chip_init(struct bmg16
 	int ret;
 	unsigned int val;
 
+	/*
+	 * Reset chip to get it in a known good state. A delay of 30ms after
+	 * reset is required according to the datasheet.
+	 */
+	regmap_write(data->regmap, BMG160_GYRO_REG_RESET,
+		     BMG160_GYRO_RESET_VAL);
+	usleep_range(30000, 30700);
+
 	ret = regmap_read(data->regmap, BMG160_REG_CHIP_ID, &val);
 	if (ret < 0) {
 		dev_err(data->dev, "Error reading reg_chip_id\n");