Re: [PATCH v2 1/3] iio: accel: add support for mxc4005 accelerometer

From: Teodora Baluta
Date: Wed Aug 19 2015 - 08:09:57 EST

On Sun, Aug 16, 2015 at 08:31:54AM +0100, Jonathan Cameron wrote:
> On 13/08/15 18:31, Teodora Baluta wrote:
> > This patch adds support for Memsic MXC4005XC 3-axis accelerometer. The
> > current implementation is a minimal one as it adds raw readings for the
> > three axes and setting scale from userspace.
> >
> > Signed-off-by: Teodora Baluta <teodora.baluta@xxxxxxxxx>
> Looking pretty good. Some real nitpicks and minor suggestions
> inline. I was going to leave this on the list anyway to give
> Peter and others time for another look so thought I might as
> well be fussy. What can I say. It's Sunday morning and the
> coffee hasn't kicked in yet :)

Thanks, it's very nice to get some more feedback. :) I have missed a
couple of things and I'll send another patch set asap.

>
> Jonathan
> > ---
> > drivers/iio/accel/Kconfig | 11 ++
> > drivers/iio/accel/Makefile | 2 +
> > drivers/iio/accel/mxc4005.c | 358 ++++++++++++++++++++++++++++++++++++++++++++
> > 3 files changed, 371 insertions(+)
> > create mode 100644 drivers/iio/accel/mxc4005.c
> >
> > diff --git a/drivers/iio/accel/Kconfig b/drivers/iio/accel/Kconfig
> > index a59047d..69302be 100644
> > --- a/drivers/iio/accel/Kconfig
> > +++ b/drivers/iio/accel/Kconfig
> > @@ -137,6 +137,17 @@ config MMA9553
> > To compile this driver as a module, choose M here: the module
> > will be called mma9553.
> >
> > +config MXC4005
> > + tristate "Memsic MXC4005XC 3-Axis Accelerometer Driver"
> > + depends on I2C
> > + select REGMAP_I2C
> > + help
> > + Say yes here to build support for the Memsic MXC4005XC 3-axis
> > + accelerometer.
> > +
> > + To compile this driver as a module, choose M. The module will be
> > + called mxc4005.
> > +
> > 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 ebd2675..020dda0 100644
> > --- a/drivers/iio/accel/Makefile
> > +++ b/drivers/iio/accel/Makefile
> > @@ -14,6 +14,8 @@ obj-$(CONFIG_MMA9551_CORE) += mma9551_core.o
> > obj-$(CONFIG_MMA9551) += mma9551.o
> > obj-$(CONFIG_MMA9553) += mma9553.o
> >
> > +obj-$(CONFIG_MXC4005) += mxc4005.o
> > +
> > obj-$(CONFIG_STK8312) += stk8312.o
> > obj-$(CONFIG_STK8BA50) += stk8ba50.o
> >
> > diff --git a/drivers/iio/accel/mxc4005.c b/drivers/iio/accel/mxc4005.c
> > new file mode 100644
> > index 0000000..76a7954
> > --- /dev/null
> > +++ b/drivers/iio/accel/mxc4005.c
> > @@ -0,0 +1,358 @@
> > +/*
> > + * 3-axis accelerometer driver for MXC4005XC Memsic sensor
> > + *
> > + * Copyright (c) 2014, Intel Corporation.
> > + *
> > + * This program is free software; you can redistribute it and/or modify it
> > + * under the terms and conditions of the GNU General Public License,
> > + * version 2, as published by the Free Software Foundation.
> > + *
> > + * This program is distributed in the hope it will be useful, but WITHOUT
> > + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
> > + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
> > + * more details.
> > + */
> > +
> > +#include <linux/module.h>
> > +#include <linux/i2c.h>
> > +#include <linux/iio/iio.h>
> > +#include <linux/acpi.h>
> > +#include <linux/regmap.h>
> > +#include <linux/iio/sysfs.h>
> > +
> > +#define MXC4005_DRV_NAME "mxc4005"
> > +#define MXC4005_REGMAP_NAME "mxc4005_regmap"
> You don't actually use the above... Guessing you did mean
> to but used drv_name instead in the regmap configuration.

That's right. :(

> > +
> > +#define MXC4005_REG_XOUT_UPPER 0x03
> > +#define MXC4005_REG_XOUT_LOWER 0x04
> > +#define MXC4005_REG_YOUT_UPPER 0x05
> > +#define MXC4005_REG_YOUT_LOWER 0x06
> > +#define MXC4005_REG_ZOUT_UPPER 0x07
> > +#define MXC4005_REG_ZOUT_LOWER 0x08
> > +
> > +#define MXC4005_REG_CONTROL 0x0D
> > +#define MXC4005_REG_CONTROL_MASK_FSR GENMASK(6, 5)
> > +#define MXC4005_CONTROL_FSR_SHIFT 5
> > +
> > +#define MXC4005_REG_DEVICE_ID 0x0E
> > +
> > +enum mxc4005_axis {
> > + AXIS_X,
> > + AXIS_Y,
> > + AXIS_Z,
> > +};
> > +
> > +enum mxc4005_range {
> > + MXC4005_RANGE_2G,
> > + MXC4005_RANGE_4G,
> > + MXC4005_RANGE_8G,
> > +};
> > +
> > +struct mxc4005_data {
> > + struct i2c_client *client;
> In a regmap cleanup series someone posted the other day,
> they just put struct device *dev in here instead and
> assigned data.dev = client->dev;
>
> Result is slightly cleaner code. Worth doing here?
>

Worth a change for this since I am always doing client->dev.

> > + struct mutex mutex;
> > + struct regmap *regmap;
> > +};
> > +
> > +/*
> > + * MXC4005 can operate in the following ranges:
> > + * +/- 2G, 4G, 8G (the default +/-2G)
> > + *
> > + * (2 + 2) * 9.81 / (2^12 - 1) = 0.009582
> > + * (4 + 4) * 9.81 / (2^12 - 1) = 0.019164
> > + * (8 + 8) * 9.81 / (2^12 - 1) = 0.038329
> > + */
> > +static const struct {
> > + u8 range;
> > + int scale;
> > +} mxc4005_scale_table[] = {
> > + {MXC4005_RANGE_2G, 9582},
> > + {MXC4005_RANGE_4G, 19164},
> > + {MXC4005_RANGE_8G, 38329},
> > +};
> > +
> > +
> > +static IIO_CONST_ATTR(in_accel_scale_available, "0.009582 0.019164 0.038329");
> > +
> > +static struct attribute *mxc4005_attributes[] = {
> > + &iio_const_attr_in_accel_scale_available.dev_attr.attr,
> > + NULL,
> > +};
> > +
> > +static const struct attribute_group mxc4005_attrs_group = {
> > + .attrs = mxc4005_attributes,
> > +};
> > +
> > +static bool mxc4005_is_readable_reg(struct device *dev, unsigned int reg)
> > +{
> > + switch (reg) {
> > + case MXC4005_REG_XOUT_UPPER:
> > + case MXC4005_REG_XOUT_LOWER:
> > + case MXC4005_REG_YOUT_UPPER:
> > + case MXC4005_REG_YOUT_LOWER:
> > + case MXC4005_REG_ZOUT_UPPER:
> > + case MXC4005_REG_ZOUT_LOWER:
> > + case MXC4005_REG_DEVICE_ID:
> > + case MXC4005_REG_CONTROL:
> > + return true;
> > + default:
> > + return false;
> > + }
> > +}
> > +
> > +static bool mxc4005_is_writeable_reg(struct device *dev, unsigned int reg)
> > +{
> > + switch (reg) {
> > + case MXC4005_REG_CONTROL:
> > + return true;
> > + default:
> > + return false;
> > + }
> > +}
> > +
> > +static const struct regmap_config mxc4005_regmap_config = {
> > + .name = MXC4005_DRV_NAME,
> > +
> > + .reg_bits = 8,
> > + .val_bits = 8,
> > +
> > + .max_register = MXC4005_REG_DEVICE_ID,
> > + .cache_type = REGCACHE_NONE,
> REGCACHE_NONE is the default. No need to specify it here.
> (enum value of 0)

Ok. Will remove this.

> > +
> > + .readable_reg = mxc4005_is_readable_reg,
> > + .writeable_reg = mxc4005_is_writeable_reg,
> > +};
> > +
> > +static int mxc4005_read_axis(struct mxc4005_data *data,
> > + unsigned int addr)
> > +{
> > + __be16 reg;
> > + int ret;
> > +
> > + ret = regmap_bulk_read(data->regmap, addr, (u8 *) &reg, sizeof(reg));
> > + if (ret < 0) {
> > + dev_err(&data->client->dev, "failed to read reg %02x\n", addr);
> > + return ret;
> > + }
> > +
> > + return be16_to_cpu(reg);
> > +}
> > +
> > +static int mxc4005_read_scale(struct mxc4005_data *data)
> > +{
> > + unsigned int reg;
> > + int ret;
> > + int i;
> > +
> > + ret = regmap_read(data->regmap, MXC4005_REG_CONTROL, &reg);
> > + if (ret < 0) {
> > + dev_err(&data->client->dev, "failed to read reg_control\n");
> > + return ret;
> > + }
> > +
> > + i = reg >> MXC4005_CONTROL_FSR_SHIFT;
> > +
> > + if (i < 0 || i >= ARRAY_SIZE(mxc4005_scale_table))
> > + return -EINVAL;
> > +
> > + return mxc4005_scale_table[i].scale;
> > +}
> > +
> > +static int mxc4005_set_scale(struct mxc4005_data *data, int val)
> > +{
> > + unsigned int reg;
> > + int i;
> > + int ret;
> > +
> > + for (i = 0; i < ARRAY_SIZE(mxc4005_scale_table); i++) {
> > + if (mxc4005_scale_table[i].scale == val) {
> > + reg = i << MXC4005_CONTROL_FSR_SHIFT;
> > + ret = regmap_update_bits(data->regmap,
> > + MXC4005_REG_CONTROL,
> > + MXC4005_REG_CONTROL_MASK_FSR,
> > + reg);
> > + if (ret < 0)
> > + dev_err(&data->client->dev,
> > + "failed to write reg_control\n");
> > + return ret;
> > + }
> > + }
> > +
> > + return -EINVAL;
> > +}
> > +
> > +static int mxc4005_read_raw(struct iio_dev *indio_dev,
> > + struct iio_chan_spec const *chan,
> > + int *val, int *val2, long mask)
> > +{
> > + struct mxc4005_data *data = iio_priv(indio_dev);
> > + int ret;
> > +
> > + switch (mask) {
> > + case IIO_CHAN_INFO_RAW:
> > + switch (chan->type) {
> > + case IIO_ACCEL:
> > + if (iio_buffer_enabled(indio_dev))
> > + return -EBUSY;
> > +
> > + ret = mxc4005_read_axis(data, chan->address);
> > + if (ret < 0)
> > + return ret;
> > + *val = sign_extend32(ret >> 4, 11);
> > + return IIO_VAL_INT;
> > + default:
> > + return -EINVAL;
> > + }
> > + case IIO_CHAN_INFO_SCALE:
> > + ret = mxc4005_read_scale(data);
> > + if (ret < 0)
> > + return ret;
> > +
> > + *val = 0;
> > + *val2 = ret;
> > + return IIO_VAL_INT_PLUS_MICRO;
> > + default:
> > + return -EINVAL;
> > + }
> > +}
> > +
> > +static int mxc4005_write_raw(struct iio_dev *indio_dev,
> > + struct iio_chan_spec const *chan,
> > + int val, int val2, long mask)
> > +{
> > + struct mxc4005_data *data = iio_priv(indio_dev);
> > +
> > + switch (mask) {
> > + case IIO_CHAN_INFO_SCALE:
> > + if (val != 0)
> > + return -EINVAL;
> > +
> > + return mxc4005_set_scale(data, val2);
> > + default:
> > + return -EINVAL;
> > + }
> > +}
> > +
> > +static const struct iio_info mxc4005_info = {
> > + .driver_module = THIS_MODULE,
> > + .read_raw = mxc4005_read_raw,
> > + .write_raw = mxc4005_write_raw,
> > + .attrs = &mxc4005_attrs_group,
> > +};
> > +
> > +#define MXC4005_CHANNEL(_axis, _addr) { \
> > + .type = IIO_ACCEL, \
> > + .modified = 1, \
> > + .channel2 = IIO_MOD_##_axis, \
> > + .address = _addr, \
> > + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
> > + .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
> > +}
> > +
> > +static const struct iio_chan_spec mxc4005_channels[] = {
> > + MXC4005_CHANNEL(X, MXC4005_REG_XOUT_UPPER),
> > + MXC4005_CHANNEL(Y, MXC4005_REG_YOUT_UPPER),
> > + MXC4005_CHANNEL(Z, MXC4005_REG_ZOUT_UPPER),
> > +};
> > +
> > +static int mxc4005_chip_init(struct mxc4005_data *data)
> > +{
> > + int ret;
> > + unsigned int reg;
> > +
> > + ret = regmap_read(data->regmap, MXC4005_REG_DEVICE_ID, &reg);
> > + if (ret < 0) {
> > + dev_err(&data->client->dev, "failed to read chip id\n");
> > + return ret;
> > + }
> > +
> > + dev_dbg(&data->client->dev, "MXC4005 chip id %02x\n", reg);
> > +
> > + return 0;
> > +}
> > +
> > +static int mxc4005_probe(struct i2c_client *client,
> > + const struct i2c_device_id *id)
> > +{
> > + struct mxc4005_data *data;
> > + struct iio_dev *indio_dev;
> > + struct regmap *regmap;
> > + int ret;
> > +
> > + indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
> > + if (!indio_dev)
> > + return -ENOMEM;
> > +
> > + regmap = devm_regmap_init_i2c(client, &mxc4005_regmap_config);
> > + if (IS_ERR(regmap)) {
> > + dev_err(&client->dev, "failed to initialize regmap\n");
> > + return PTR_ERR(regmap);
> > + }
> > +
> > + data = iio_priv(indio_dev);
> > + i2c_set_clientdata(client, indio_dev);
> > + data->client = client;
> > + data->regmap = regmap;
> > +
> > + ret = mxc4005_chip_init(data);
> > + if (ret < 0) {
> For consistency with previous error message (yeah I'm getting
> picky ;) - initialize

Yes, true. :)

> > + dev_err(&client->dev, "failed to init chip\n");
> > + return ret;
> > + }
> > +
> > + mutex_init(&data->mutex);
> > +
> > + indio_dev->dev.parent = &client->dev;
> > + indio_dev->channels = mxc4005_channels;
> > + indio_dev->num_channels = ARRAY_SIZE(mxc4005_channels);
> > + indio_dev->name = MXC4005_DRV_NAME;
> > + indio_dev->modes = INDIO_DIRECT_MODE;
> > + indio_dev->info = &mxc4005_info;
> > +
> > + ret = iio_device_register(indio_dev);
> > + if (ret < 0) {
> > + dev_err(&client->dev,
> > + "unable to register iio device %d\n", ret);
> > + return ret;
> > + }
> > +
> > + return 0;
> > +}
> > +
> > +static int mxc4005_remove(struct i2c_client *client)
> > +{
> > + struct iio_dev *indio_dev = i2c_get_clientdata(client);
> > +
> Roll the line above and the one below into one. No point in the
> separation.

Ok.

> > + iio_device_unregister(indio_dev);
> > +
> > + return 0;
> > +}
> > +
> > +static const struct acpi_device_id mxc4005_acpi_match[] = {
> > + {"MXC4005", 0},
> > + { },
> > +};
> > +MODULE_DEVICE_TABLE(acpi, mxc4005_acpi_match);
> > +
> > +static const struct i2c_device_id mxc4005_id[] = {
> > + {"mxc4005", 0},
> > + { },
> > +};
> For consistency no blank line here.

Ok.

> > +
> > +MODULE_DEVICE_TABLE(i2c, mxc4005_id);
> > +
> > +static struct i2c_driver mxc4005_driver = {
> > + .driver = {
> > + .name = MXC4005_DRV_NAME,
> > + .acpi_match_table = ACPI_PTR(mxc4005_acpi_match),
> > + },
> > + .probe = mxc4005_probe,
> > + .remove = mxc4005_remove,
> > + .id_table = mxc4005_id,
> > +};
> > +
> > +module_i2c_driver(mxc4005_driver);
> > +
> > +MODULE_AUTHOR("Teodora Baluta <teodora.baluta@xxxxxxxxx>");
> > +MODULE_LICENSE("GPL v2");
> > +MODULE_DESCRIPTION("MXC4005 3-axis accelerometer driver");
> >
>
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