Re: [PATCH 2/2] iio: accel: Add driver for Murata SCA3300 accelerometer
From: Tomas Melin
Date: Fri Apr 16 2021 - 08:17:27 EST
On 4/15/21 11:41 AM, Tomas Melin wrote:
While working on updates I did notice something new which I cannot
reproduce on older (5.10.17 kernel) version. If compiling this as a
module, getting error while
unloading module:
[ 40.200084] Unable to handle kernel NULL pointer dereference at
virtual address 00000104
...
[ 40.510054] Backtrace:
[ 40.512502] [<c06c5e0c>] (iio_device_ioctl_handler_unregister) from
[<c06ca8c4>] (iio_buffers_free_sysfs_and_mask+0x2c/0x6c)
[ 40.523735] [<c06ca898>] (iio_buffers_free_sysfs_and_mask) from
[<c06c4a18>] (iio_device_unregister+0xa8/0xac)
[ 40.533746] r5:c1811228 r4:c1811000
[ 40.537318] [<c06c4970>] (iio_device_unregister) from [<c06c4a38>]
(devm_iio_device_unreg+0x1c/0x20)
[ 40.546461] r5:c2415000 r4:c25bab80
[ 40.550025] [<c06c4a1c>] (devm_iio_device_unreg) from [<c0556820>]
(release_nodes+0x1c0/0x1f0)
[ 40.558654] [<c0556660>] (release_nodes) from [<c0556bb0>]
(devres_release_all+0x40/0x60)
[ 40.566847] r10:00000081 r9:c2350000 r8:c0100264 r7:00000081
r6:bf00c010 r5:c19be000
[ 40.574669] r4:c1a91c00
[ 40.577194] [<c0556b70>] (devres_release_all) from [<c055216c>]
(device_release_driver_internal+0x120/0x1cc)
[ 40.587031] r5:c19be000 r4:c1a91c00
[ 40.590596] [<c055204c>] (device_release_driver_internal) from
[<c05522b4>] (driver_detach+0x54/0x90)
[ 40.599828] r7:00000081 r6:00000000 r5:bf00c010 r4:c1a91c00
[ 40.605482] [<c0552260>] (driver_detach) from [<c0550ba4>]
(bus_remove_driver+0x5c/0xb0)
[ 40.613583] r5:00000800 r4:bf00c010
[ 40.617148] [<c0550b48>] (bus_remove_driver) from [<c0552c38>]
(driver_unregister+0x38/0x5c)
[ 40.625596] r5:00000800 r4:bf00c010
[ 40.629161] [<c0552c00>] (driver_unregister) from [<bf00a760>]
(sca3300_driver_exit+0x14/0x8b4 [sca3300])
[ 40.638747] r5:00000800 r4:bf00c080
[ 40.642311] [<bf00a74c>] (sca3300_driver_exit [sca3300]) from
[<c01c06f0>] (sys_delete_module+0x16c/0x238)
[ 40.651990] [<c01c0584>] (sys_delete_module) from [<c0100244>]
(__sys_trace_return+0x0/0x1c)
[ 40.660435] Exception stack(0xc2351fa8 to 0xc2351ff0)
[ 40.665484] 1fa0: 0050e5a8 00000000 0050e5e4
00000800 081d4b00 bec18af4
[ 40.673661] 1fc0: 0050e5a8 00000000 bec18b50 00000081 bec18e51
0050e190 00000001 bec18d3c
[ 40.681834] 1fe0: 0050cf70 bec18afc 004f1ec8 b6ecb27c
[ 40.686887] r6:bec18b50 r5:00000000 r4:0050e5a8
[ 40.691507] Code: e8bd4000 e1c020d0 e3a0cc01 e3001122 (e5823004)
[ 40.707675] ---[ end trace 189882b050077333 ]---
This happens when building against linux-next
5.12.0-rc6-next-20210409. I'm failing to see what is wrong. Any ideas?
Thanks,
Tomas
Tested further that for this driver, loading and unloading as module
works fine until commit:
commit f73f7f4da581875f9b1f2fb8ebd1ab15ed634488
Author: Alexandru Ardelean <alexandru.ardelean@xxxxxxxxxx>
Date: Mon Feb 15 12:40:39 2021 +0200
iio: buffer: add ioctl() to support opening extra buffers for IIO
device
Any thoughts what causes this issue?
Thanks,
Tomas
---
drivers/iio/accel/Kconfig | 13 ++
drivers/iio/accel/Makefile | 1 +
drivers/iio/accel/sca3300.c | 434
++++++++++++++++++++++++++++++++++++
3 files changed, 448 insertions(+)
create mode 100644 drivers/iio/accel/sca3300.c
diff --git a/drivers/iio/accel/Kconfig b/drivers/iio/accel/Kconfig
index cceda3cecbcf..0dbf7b648e8a 100644
--- a/drivers/iio/accel/Kconfig
+++ b/drivers/iio/accel/Kconfig
@@ -450,6 +450,19 @@ config SCA3000
To compile this driver as a module, say M here: the module
will be
called sca3000.
+config SCA3300
+ tristate "Murata SCA3300 3-Axis Accelerometer Driver"
+ depends on SPI
+ select CRC8
+ select IIO_BUFFER
+ select IIO_TRIGGERED_BUFFER
+ help
+ Say yes here to build support for Murata SCA3300 3-Axis
+ accelerometer.
+
+ To compile this driver as a module, choose M here: the module
will be
+ called sca3300.
+
config STK8312
tristate "Sensortek STK8312 3-Axis Accelerometer Driver"
depends on I2C
diff --git a/drivers/iio/accel/Makefile b/drivers/iio/accel/Makefile
index 32cd1342a31a..4b56527a2b97 100644
--- a/drivers/iio/accel/Makefile
+++ b/drivers/iio/accel/Makefile
@@ -50,6 +50,7 @@ obj-$(CONFIG_MXC4005) += mxc4005.o
obj-$(CONFIG_MXC6255) += mxc6255.o
obj-$(CONFIG_SCA3000) += sca3000.o
+obj-$(CONFIG_SCA3300) += sca3300.o
obj-$(CONFIG_STK8312) += stk8312.o
obj-$(CONFIG_STK8BA50) += stk8ba50.o
diff --git a/drivers/iio/accel/sca3300.c b/drivers/iio/accel/sca3300.c
new file mode 100644
index 000000000000..112fb88ecd3a
--- /dev/null
+++ b/drivers/iio/accel/sca3300.c
@@ -0,0 +1,434 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) Vaisala Oyj. All rights reserved.
Give a year for the copyright notice if you can.
+ */
+#include <linux/crc8.h>
+#include <linux/delay.h>
+#include <linux/iio/buffer.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+#include <linux/iio/trigger_consumer.h>
+#include <linux/iio/triggered_buffer.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/spi/spi.h>
+
+#define SCA3300_ALIAS "sca3300"
+
+#define SCA3300_REG_STATUS 0x6
+#define SCA3300_REG_MODE 0xd
+#define SCA3300_REG_WHOAMI 0x10
+#define SCA3300_VALUE_SW_RESET 0x20
+#define SCA3300_CRC8_POLYNOMIAL 0x1d
+#define SCA3300_X_READ 0
I wouldn't bother defining this.
+#define SCA3300_X_WRITE BIT(7)
Even this one is something I'd just put inline with a comment.
+#define SCA3300_DEVICE_ID 0x51
+#define SCA3300_RS_ERROR 0x3
+
+enum sca3300_scan_indexes {
+ SCA3300_ACC_X = 0,
+ SCA3300_ACC_Y,
+ SCA3300_ACC_Z,
+ SCA3300_TEMP,
+ SCA3300_TIMESTAMP,
+};
+
+#define SCA3300_ACCEL_CHANNEL(index, reg, axis) { \
+ .type = IIO_ACCEL, \
+ .address = reg, \
+ .modified = 1, \
+ .channel2 = IIO_MOD_##axis, \
+ .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | \
+ BIT(IIO_CHAN_INFO_PROCESSED), \
As mentioned below, don't provide PROCESSED. Userspace is better at
handling the
conversion so leave it to them.
+ .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
+ .scan_index = index, \
+ .scan_type = { \
+ .sign = 's', \
+ .realbits = 16, \
+ .storagebits = 16, \
+ .shift = 0, \
+ .endianness = IIO_CPU, \
+ }, \
+ }
+
+static const struct iio_chan_spec sca3300_channels[] = {
+ SCA3300_ACCEL_CHANNEL(SCA3300_ACC_X, 0x1, X),
+ SCA3300_ACCEL_CHANNEL(SCA3300_ACC_Y, 0x2, Y),
+ SCA3300_ACCEL_CHANNEL(SCA3300_ACC_Z, 0x3, Z),
+ {
+ .type = IIO_TEMP,
+ .address = 0x5,
+ .scan_index = SCA3300_TEMP,
+ .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
+ .scan_type = {
+ .sign = 's',
+ .realbits = 16,
+ .storagebits = 16,
+ .shift = 0,
+ .endianness = IIO_CPU,
+ },
+ },
+ IIO_CHAN_SOFT_TIMESTAMP(4),
+};
+
+static const int sca3300_accel_scale[] = {2700, 1350, 5400, 5400};
+
+static const unsigned long sca3300_scan_masks[] = {
+ BIT(SCA3300_ACC_X) | BIT(SCA3300_ACC_Y) | BIT(SCA3300_ACC_Z) |
+ BIT(SCA3300_TEMP),
+ 0};
+
+/**
+ * SCA3300 device data
run scripts/kernel-doc over the file and fix the warnings + errors.
+ *
+ * @spi SPI device structure
+ * @opmode Device operation mode
+ * @lock Data buffer lock
+ * @txbuf Transmit buffer
+ * @rxbuf Receive buffer
+ * @scan Triggered buffer. Four channel 16-bit data + 64-bit timestamp
+ */
+struct sca3300_data {
+ struct spi_device *spi;
+ u32 opmode;
+ struct mutex lock;
+ u8 txbuf[4];
+ u8 rxbuf[4];
+ struct {
+ s16 channels[4];
+ s64 ts __aligned(sizeof(s64));
+ } scan;
+};
+
+DECLARE_CRC8_TABLE(sca3300_crc_table);
+
+static int sca3300_transfer(struct sca3300_data *sca_data, int *val)
+{
+ struct spi_delay delay = {.value = 10, .unit =
SPI_DELAY_UNIT_USECS};
+ int32_t ret;
+ int rs;
+ u8 crc;
+ struct spi_transfer xfers[2] = {
+ {
+ .tx_buf = sca_data->txbuf,
+ .rx_buf = NULL,
+ .len = ARRAY_SIZE(sca_data->txbuf),
+ .delay = delay,
+ .cs_change = 1,
+ },
+ {
+ .tx_buf = NULL,
+ .rx_buf = sca_data->rxbuf,
+ .len = ARRAY_SIZE(sca_data->rxbuf),
+ .delay = delay,
+ .cs_change = 0,
+ }
+ };
+
+ /* inverted crc value as described in device data sheet */
+ crc = ~crc8(sca3300_crc_table, &sca_data->txbuf[0], 3,
CRC8_INIT_VALUE);
+ sca_data->txbuf[3] = crc;
+
+ ret = spi_sync_transfer(sca_data->spi, xfers, 2);
Use ARRAY_SIZE(xfers) instead of 2.
+ if (ret < 0) {
+ dev_err(&sca_data->spi->dev,
+ "transfer error, error: %d\n", ret);
+ return -EIO;
+ }
+
+ crc = ~crc8(sca3300_crc_table, &sca_data->rxbuf[0], 3,
CRC8_INIT_VALUE);
+ if (sca_data->rxbuf[3] != crc) {
+ dev_err(&sca_data->spi->dev, "CRC checksum mismatch");
+ return -EIO;
+ }
+
+ /* get return status */
+ rs = sca_data->rxbuf[0] & 0x03;
+ if (rs == SCA3300_RS_ERROR)
+ return rs;
+
+ *val = (s16)(sca_data->rxbuf[2] | (sca_data->rxbuf[1] << 8));
Preference for an unaligned endian conversion here and explicit sign
extend e.g
something like
sign_extend32(get_unaligned_le16(&sca_data->rxbuf[1]), 15)
+
+ return 0;
+}
+
+static int sca3300_read_reg(struct sca3300_data *sca_data, u8 reg,
int *val)
+{
+ int ret;
+
+ mutex_lock(&sca_data->lock);
+ sca_data->txbuf[0] = SCA3300_X_READ | (reg << 2);
+ ret = sca3300_transfer(sca_data, val);
+ if (ret > 0) {
+ sca_data->txbuf[0] = SCA3300_X_READ | (SCA3300_REG_STATUS
<< 2);
+ ret = sca3300_transfer(sca_data, val);
+ /* status 0 = startup, 0x2 = mode change */
+ if (ret > 0 && *val != 0 && *val != 0x2) {
+ dev_err_ratelimited(&sca_data->spi->dev,
+ "device status: %x\n",
+ (u16)*val);
+ mutex_unlock(&sca_data->lock);
+ return -EIO;
+ }
+ if (ret > 0)
+ ret = 0;
+ }
+ mutex_unlock(&sca_data->lock);
+
+ return ret;
+}
+
+static int sca3300_write_reg(struct sca3300_data *sca_data, u8 reg,
int val)
+{
+ int reg_val = 0;
+ int ret;
+
+ mutex_lock(&sca_data->lock);
+ sca_data->txbuf[0] = SCA3300_X_WRITE | (reg << 2);
+ sca_data->txbuf[1] = val >> 8;
+ sca_data->txbuf[2] = val & 0xFF;
Prefer (Slightly) an unaligned put.
+ ret = sca3300_transfer(sca_data, ®_val);
+ if (ret > 0) {
Factor this error handling out to another function, plus trigger it
from an
appropriate standard error code rather than a positive return value.
+ sca_data->txbuf[0] = SCA3300_X_READ | (SCA3300_REG_STATUS
<< 2);
+ ret = sca3300_transfer(sca_data, ®_val);
+ /* status 0 = startup, 0x2 = mode change */
+ if (ret > 0 && reg_val != 0 && reg_val != 0x2) {
+ dev_err_ratelimited(&sca_data->spi->dev,
+ "device status: %x\n",
+ (u16)reg_val);
+ mutex_unlock(&sca_data->lock);
+ return -EIO;
+ }
+ if (ret > 0)
+ ret = 0;
Whenever you get this sort of juggling it rather implies your design is
less than ideal.
+ }
+ mutex_unlock(&sca_data->lock);
+
+ return ret;
+}
+
+static int sca3300_write_raw(struct iio_dev *indio_dev,
+ struct iio_chan_spec const *chan,
+ int val, int val2, long mask)
+{
+ struct sca3300_data *data = iio_priv(indio_dev);
+
+ switch (mask) {
+ case IIO_CHAN_INFO_SCALE:
+ if (val < 0 || val > 3)
+ return -EINVAL;
No. Scale values need to be the value of 1LSB not a random integer
that requires you to look up the datasheet.
+ return sca3300_write_reg(data, SCA3300_REG_MODE, val);
+ default:
+ return -EINVAL;
+ }
+}
+
+static int sca3300_read_raw(struct iio_dev *indio_dev,
+ struct iio_chan_spec const *chan,
+ int *val, int *val2, long mask)
+{
+ struct sca3300_data *data = iio_priv(indio_dev);
+ int ret;
+ int reg_val;
+
+ switch (mask) {
+ case IIO_CHAN_INFO_RAW:
+ ret = sca3300_read_reg(data, chan->address, val);
+ if (ret < 0)
+ return ret;
+ return IIO_VAL_INT;
+ case IIO_CHAN_INFO_SCALE:
+ ret = sca3300_read_reg(data, SCA3300_REG_MODE, ®_val);
+ if (ret < 0)
+ return ret;
+ *val = sca3300_accel_scale[reg_val];
Scale is very very rarely an integer value which makes me wonder what
you are returning here... It should be the multiplier needed to
take the raw value to a reading in m/sec^2 Given you use it as
fractional
below, I'm guessing this is 1/scale_value?
+ return IIO_VAL_INT;
+ case IIO_CHAN_INFO_PROCESSED:
Don't provide processed here. Userspace needs to do the conversion
itself
(and given it has floating point easily available will probably do a
better
job than we can). I'm assuming the mode can't autonomously change?
+ ret = sca3300_read_reg(data, SCA3300_REG_MODE, ®_val);
+ if (ret < 0)
+ return ret;
+ *val2 = sca3300_accel_scale[reg_val];
+ ret = sca3300_read_reg(data, chan->address, val);
+ if (ret < 0)
+ return ret;
+ return IIO_VAL_FRACTIONAL;
+ default:
+ return -EINVAL;
+ }
+}
+
+static irqreturn_t sca3300_trigger_handler(int irq, void *p)
+{
+ struct iio_poll_func *pf = p;
+ struct iio_dev *indio_dev = pf->indio_dev;
+ struct sca3300_data *data = iio_priv(indio_dev);
+ s64 time_ns = iio_get_time_ns(indio_dev);
Is the timestamp at the start more accurate that that at the end
of reading the channels? If not, just put this inline in the
iio_push_to_buffers_with_timestamp() call.
+ int bit, ret, val, i = 0;
+
+ for_each_set_bit(bit, indio_dev->active_scan_mask,
+ indio_dev->masklength) {
+ ret = sca3300_read_reg(data, sca3300_channels[bit].address,
+ &val);
+ if (ret < 0)
Given we can't return an error code from interrupt handlers, it is
usually
a good idea to print something to the log. Otherwise we get missing data
with no idea of why..
+ goto out;
+ if (ARRAY_SIZE(data->scan.channels) > i)
How could this not be true? If it's always true, don't bother
checking i.
+ ((s16 *)data->scan.channels)[i++] = val;
+ }
+
+ iio_push_to_buffers_with_timestamp(indio_dev, &data->scan,
time_ns);
+out:
+ iio_trigger_notify_done(indio_dev->trig);
+
+ return IRQ_HANDLED;
+}
+
+static int sca3300_init(struct sca3300_data *sca_data,
+ struct iio_dev *indio_dev)
+{
+ int ret;
+ int value = 0;
+
+ if (sca_data->opmode < 1 || sca_data->opmode > 4)
+ return -EINVAL;
Whilst this is going anyway, better to check that next to where
it is read so we drop out immediately rather than buried in this
function.
+
+ ret = sca3300_write_reg(sca_data, SCA3300_REG_MODE,
+ SCA3300_VALUE_SW_RESET);
+ if (ret != 0)
+ return ret;
For sleeps, good to reference which section in data sheet gives the
timing.
+ usleep_range(2e3, 10e3);
+
+ ret = sca3300_write_reg(sca_data, SCA3300_REG_MODE,
+ sca_data->opmode - 1);
+ if (ret != 0)
if (ret) see below.
+ return ret;
+ msleep(100);
Again, document where the time comes from. Saves reviewers time if
they want to check it. (I'm too lazy :)
+ ret = sca3300_read_reg(sca_data, SCA3300_REG_WHOAMI, &value);
+ if (ret != 0)
if (ret) is more idiomatic in kernel code.
+ return ret;
+
+ if (value != SCA3300_DEVICE_ID) {
+ dev_err(&sca_data->spi->dev, "device id not expected
value\n");
Perhaps useful to print what was expected and what was seen. Maybe it's
a new variant and this might help the user to identify that and add
it to the
driver.
+ return -EIO;
-EINVAL probably more appropriate return.
+ }
+ return 0;
+}
+
+static int sca3300_debugfs_reg_access(struct iio_dev *indio_dev,
+ unsigned int reg, unsigned int writeval,
+ unsigned int *readval)
+{
+ struct sca3300_data *data = iio_priv(indio_dev);
+ int value;
+ int ret;
+
+ if (reg > 0x1f)
Use a define that names that register.
+ return -EINVAL;
+
+ if (!readval)
+ return sca3300_write_reg(data, reg, writeval);
+
+ ret = sca3300_read_reg(data, reg, &value);
+ if (ret < 0)
+ return ret;
+
+ *readval = (unsigned int)value;
+
+ return 0;
+}
+
+static const struct iio_info sca3300_info = {
+ .read_raw = sca3300_read_raw,
+ .write_raw = sca3300_write_raw,
+ .debugfs_reg_access = &sca3300_debugfs_reg_access,
+};
+
+static int sca3300_probe(struct spi_device *spi)
+{
+ struct sca3300_data *sca_data;
+ struct iio_dev *indio_dev;
+ int ret;
+
+ indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*sca_data));
+ if (!indio_dev) {
+ dev_err(&spi->dev,
+ "failed to allocate memory for iio device\n");
+ return -ENOMEM;
+ }
+
+ sca_data = iio_priv(indio_dev);
+ mutex_init(&sca_data->lock);
+ sca_data->spi = spi;
+ spi_set_drvdata(spi, indio_dev);
Won't be used once using devm as below and remove() is dropped, so
drop this.
+
+ crc8_populate_msb(sca3300_crc_table, SCA3300_CRC8_POLYNOMIAL);
+
+ indio_dev->dev.parent = &spi->dev;
+ indio_dev->info = &sca3300_info;
+ indio_dev->name = SCA3300_ALIAS;
+ indio_dev->modes = INDIO_DIRECT_MODE | INDIO_BUFFER_TRIGGERED;
BUFFER_TRIGGERED bit now set by iio_triggered_buffer_setup() so
shouldn't
be ehre as well.
+ indio_dev->channels = sca3300_channels;
+ indio_dev->num_channels = ARRAY_SIZE(sca3300_channels);
+ indio_dev->available_scan_masks = sca3300_scan_masks;
+
+ if (spi->dev.of_node) {
+ ret = of_property_read_u32(spi->dev.of_node, "murata,opmode",
Please use generic firmware access calls rather than the of specific
ones.
That lets us get ACPI support for free :)
As per the binding review however, this one needs to go in favour of
userspace
control of scale + filter frequencies / sampling freq.
+ &sca_data->opmode);
+ if (ret < 0)
+ return ret;
+ }
+
+ ret = sca3300_init(sca_data, indio_dev);
+ if (ret < 0) {
+ dev_err(&spi->dev, "failed to init device, error: %d\n", ret);
+ return ret;
+ }
+
+ ret = iio_triggered_buffer_setup(indio_dev,
iio_pollfunc_store_time,
+ sca3300_trigger_handler, NULL);
devm_iio_triggered_buffer_setup() and you can drop the manual cleanup
in remove()
and hence drop remove() entirely as nothing else left.
+ if (ret < 0) {
+ dev_err(&spi->dev,
+ "iio triggered buffer setup failed, error: %d\n", ret);
+ return ret;
+ }
+
+ ret = devm_iio_device_register(&spi->dev, indio_dev);
+ if (ret < 0) {
+ dev_err(&spi->dev, "iio device register failed, error: %d\n",
+ ret);
+ iio_triggered_buffer_cleanup(indio_dev);
With devm above, no need to manually clean this up.
+ return ret;
+ }
+
+ return 0;
+}
+
+static int sca3300_remove(struct spi_device *spi)
+{
+ struct iio_dev *indio_dev = spi_get_drvdata(spi);
+
+ iio_triggered_buffer_cleanup(indio_dev);
+ return 0;
+}
+
+static const struct of_device_id sca3300_dt_ids[] = {
+ { .compatible = "murata,sca3300"},
+ {},
+};
+MODULE_DEVICE_TABLE(of, sca3300_dt_ids);
+
+static struct spi_driver sca3300_driver = {
+ .driver = {
+ .name = SCA3300_ALIAS,
+ .owner = THIS_MODULE,
+ .of_match_table = of_match_ptr(sca3300_dt_ids),
+ },
+
+ .probe = sca3300_probe,
+ .remove = sca3300_remove,
+};
+
+module_spi_driver(sca3300_driver);
+
+MODULE_AUTHOR("Tomas Melin <tomas.melin@xxxxxxxxxxx>");
+MODULE_DESCRIPTION("Murata SCA3300 SPI Accelerometer");
+MODULE_LICENSE("GPL v2");