Re: [PATCH 2/2] iio: accel: Add driver for Murata SCA3300 accelerometer

Alexandru Ardelean
2021-04-20T08:12:55Z

(

On Mon, Apr 19, 2021 at 11:15 PM Jonathan Cameron <jic23@kernel.org> wrote:
>
> On Mon, 19 Apr 2021 20:45:08 +0100
> Jonathan Cameron <jic23@kernel.org> wrote:
>
> > On Mon, 19 Apr 2021 16:34:35 +0300
> > Tomas Melin <tomas.melin@vaisala.com> wrote:
> >
> > > Hi,
> > >
> > > On 4/18/21 1:03 PM, Jonathan Cameron wrote:
> > > > On Fri, 16 Apr 2021 15:21:14 +0300
> > > > Tomas Melin <tomas.melin@vaisala.com> wrote:
> > > >
> > > >> Updated email-address for Alexandru.
> > > >>
> > > >>
> > > >> On 4/16/21 3:17 PM, Tomas Melin wrote:
> > > >>> 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@analog.com>
> > > >>> 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?
> > > > Is this still happening after fixing the ordering in probe / remove?
> > > > (devm_iio_triggered_buffer_setup() being easiest way)
> > > >
> > > > As driver currently stands it's calling iio_triggered_buffer_cleanup
> > > > before the managed cleanup of the iio_device_register() call. That
> > > > should never happen so would be where I'd look for problems here.
> > > >
> > > > It is possible Alex's work is relying on that ordering being correct
> > > > a little more than we previously were. I could be wrong though
> > > > and could be something else going on!
> > > >
> > > > Jonathan
> > > >
> > > > +CC Alex's other email address.
> > >
> > > This is still happening with v3 of driver patchset, which uses only devm_*
> > >
> > > versions in probing. v5.12-rc7 works ok, I'm currently only seeing this
> > > using linux-next.
> >
> > Thanks for checking. I've just fired up a VM and confirmed that the same
> > thing is happening with creating and removing instances of the dummy driver.
> >
> > Will see if I can figure out what's going wrong.
>
> So the issue proved reasonably easy to track down.
> We remove the buffer ioctl handler twice. First in iio_device_unregister() in a loop
> over the list, and again later in iio_buffer_sysfs_and_mask() (called from
> the same function). (note it would happen later in the equivalent event related
> version but we have already died on the first instance which is the one Tomas hit).
>
> @Alex. Which one should we keep? Given the buffer and event code both
> clean up manually I think what we want is:
>
> @@ -1939,9 +1943,6 @@ void iio_device_unregister(struct iio_dev *indio_dev)
>
> indio_dev->info = NULL;
>
> - list_for_each_entry_safe(h, t, &iio_dev_opaque->ioctl_handlers, entry)
> - list_del(&h->entry);
> -
> iio_device_wakeup_eventset(indio_dev);
> iio_buffer_wakeup_poll(indio_dev);
>
>
> I'm going to guess something went wrong in a merge or rebased and left that
> block when it should have been removed.

No, that's not a merge/rebase gone wrong.
It's me being stupid.

Removing that loop is the good fix.
Each module doing a iio_device_ioctl_handler_register() should also do
a iio_device_ioctl_handler_unregister().

>
> Anyhow, if the above is the right fix I can roll it up into a patch tomorrow and
> get it into linux-next at least.

Sure :)

Apologies for the breakage.

>
> thanks,
>
> Jonathan
>
> >
> > Jonathan
> >
> > >
> > > Thanks,
> > >
> > > Tomas
> > >
> > >
> > > >>> 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, &reg_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, &reg_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, &reg_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, &reg_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@vaisala.com>");
> > > >>>>>> +MODULE_DESCRIPTION("Murata SCA3300 SPI Accelerometer");
> > > >>>>>> +MODULE_LICENSE("GPL v2");
> >
>