Date:	Mon, 29 Jul 2013 17:15:03 +0200 (CEST)
From:	Peter Meerwald <pmeerw@...erw.net>
To:	Oleksandr Kravchenko <x0199363@...com>
cc:	linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-doc@...r.kernel.org, grant.likely@...aro.org,
	rob.herring@...xeda.com, rob@...dley.net, jic23@....ac.uk,
	holler@...oftware.de, srinivas.pandruvada@...el.com,
	devicetree-discuss@...ts.ozlabs.org,
	Oleksandr Kravchenko <o.v.kravchenko@...ballogic.com>
Subject: Re: [PATCH 2/2] iio: add Bosch BMA180 acceleration sensor driver


kicking out drivers fast :)
few comments below; the driver exposes only minimal iio features and 
integrates input subsystem, this doesn't seem right

p.

> diff --git a/Documentation/devicetree/bindings/iio/accel/bma180.txt b/Documentation/devicetree/bindings/iio/accel/bma180.txt
> new file mode 100644
> index 0000000..7c13c84
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/iio/accel/bma180.txt
> @@ -0,0 +1,53 @@
> +* Bosch BMA180 triaxial acceleration sensor
> +
> +http://omapworld.com/BMA180_111_1002839.pdf
> +
> +Required properties:
> +
> +  - compatible : should be "bosch,bma180"
> +  - reg : the I2C address of the sensor
> +
> +Optional properties:
> +
> +  - interrupt-parent : should be the phandle for the interrupt controller
> +
> +  - interrupts : interrupt mapping for GPIO IRQ, it shuld by configured with
> +		flags IRQ_TYPE_LEVEL_HIGH | IRQ_TYPE_EDGE_RISING
> +
> +  - range : select the full scale acceleration range
> +		0 : -1g..+1g
> +		1 : -1.5g..+1.5g
> +		2 : -2g..+2g
> +		3 : -3g..+3g
> +		4 : -4g..+4g
> +		5 : -8g..+8g
> +		6 : -16g..+16g
> +
> +  - bw : select bandwidth bandwidth
> +		0 : 10Hz
> +		1 : 20Hz
> +		2 : 40Hz
> +		3 : 75Hz
> +		4 : 150Hz
> +		5 : 300Hz
> +		Don't use bandwidth frequency more than 300Hz couse it

because

> +		influences the frequency of generating new data interrupts
> +		and i2c reading phase can be longer than pheriod of interrupt

period

> +		generation.
> +
> +  - mode_config : 0 - select low noise mode, 1 - select low power mode
> +
> +  - fuzz : specifies fuzz value that is used to filter noise from the event stream
> +
> +Example:
> +
> +bma180@40 {
> +	compatible = "bosch,bma180";
> +	reg = <0x40>;
> +	interrupt-parent = <&gpio6>;
> +	interrupts = <18 (IRQ_TYPE_LEVEL_HIGH | IRQ_TYPE_EDGE_RISING)>;
> +	range = <2>;
> +	bw = <0>;
> +	mode_config = <1>;
> +	fuzz = <555>;
> +};
> diff --git a/drivers/iio/accel/Kconfig b/drivers/iio/accel/Kconfig
> index 719d83f..61fd29f 100644
> --- a/drivers/iio/accel/Kconfig
> +++ b/drivers/iio/accel/Kconfig
> @@ -3,6 +3,16 @@
>  #
>  menu "Accelerometers"
>  
> +config BMA180
> +	tristate "Bosch BMA180 3-Axis Accelerometer Driver"
> +	depends on I2C
> +	help
> +	  Say Y here if you want to build a driver for the Bosch BMA180
> +	  triaxial acceleration sensor.
> +
> +	  To compile this driver as a module, choose M here: the
> +	  module will be called bma180.
> +
>  config HID_SENSOR_ACCEL_3D
>  	depends on HID_SENSOR_HUB
>  	select IIO_BUFFER
> diff --git a/drivers/iio/accel/Makefile b/drivers/iio/accel/Makefile
> index 87d8fa2..31a36fa 100644
> --- a/drivers/iio/accel/Makefile
> +++ b/drivers/iio/accel/Makefile
> @@ -12,3 +12,5 @@ obj-$(CONFIG_IIO_ST_ACCEL_I2C_3AXIS) += st_accel_i2c.o
>  obj-$(CONFIG_IIO_ST_ACCEL_SPI_3AXIS) += st_accel_spi.o
>  
>  obj-$(CONFIG_KXSD9)	+= kxsd9.o
> +
> +obj-$(CONFIG_BMA180)	+= bma180.o

alphabetic order

> diff --git a/drivers/iio/accel/bma180.c b/drivers/iio/accel/bma180.c
> new file mode 100644
> index 0000000..9f5341f
> --- /dev/null
> +++ b/drivers/iio/accel/bma180.c
> @@ -0,0 +1,462 @@
> +/*
> + * bma180.c - IIO driver for Bosch BMA180 triaxial acceleration sensor
> + *
> + * Copyright 2013 Oleksandr Kravchenko <x0199363@...com>
> + *
> + * This file is subject to the terms and conditions of version 2 of
> + * the GNU General Public License.  See the file COPYING in the main
> + * directory of this archive for more details.
> + */
> +
> +#include <linux/module.h>
> +#include <linux/i2c.h>
> +#include <linux/interrupt.h>
> +#include <linux/delay.h>
> +#include <linux/input.h>
> +#include <linux/of.h>
> +#include <linux/bitops.h>
> +#include <linux/iio/iio.h>
> +#include <linux/iio/sysfs.h>
> +#include <linux/iio/events.h>
> +
> +#define BMA180_DRV_NAME "bma180"
> +#define BMA180_IRQ_NAME "bma180_event"
> +
> +/* Register set */
> +#define BMA180_CHIP_ID		0x00 /* Need to distinguish BMA180 from other */
> +#define BMA180_ACC_X_LSB	0x02 /* First of 6 registers of accel data */
> +#define BMA180_CTRL_REG0	0x0d
> +#define BMA180_RESET		0x10
> +#define BMA180_BW_TCS		0x20
> +#define BMA180_CTRL_REG3	0x21
> +#define BMA180_TCO_Z		0x30
> +#define BMA180_OFFSET_LSB1	0x35
> +
> +/* Control bits */
> +#define BMA180_SLEEP		BIT(1) /* 1 - chip will sleep */
> +#define BMA180_DIS_WAKE_UP	BIT(0) /* Disable wake up mode */
> +#define BMA180_EE_W		BIT(4) /* Unlock writing to addr. from 0x20 */
> +#define BMA180_NEW_DATA_INT	BIT(1) /* Intr every new accel data is ready */
> +#define BMA180_SMP_SKIP		BIT(0) /* Sample skipping mode */

maybe say which bits belong to which CTRL reg?

> +
> +/* Bit masks fo registerts bit fields */

typos: fo, registerts

> +#define BMA180_RANGE		0x0e /* Range of accel measurment */
> +#define BMA180_BW		0xf0 /* Accel measurmend bandwidth */

typo: measurmend

> +#define BMA180_MODE_CONFIG	0x03 /* Config operation modes */
> +
> +/* We have write this value in reset register to do soft reset */

have 'to' write

> +#define BMA180_RESET_VAL	0xb6
> +
> +/* Chip operation modes */
> +#define BMA180_LOW_NOISE	0x00
> +#define BMA180_LOW_POWER	0x03
> +
> +struct bma180_data {
> +	struct i2c_client *client;
> +	struct input_dev *input_dev;
> +	struct mutex mutex;
> +	int sleep_state;
> +	int range;
> +	int bw;
> +	int mode;
> +	int fuzz;
> +	int acc_reg[3];
> +};
> +
> +enum bma180_axis {
> +	AXIS_X,
> +	AXIS_Y,
> +	AXIS_Z,
> +};
> +
> +struct bma180_range {
> +	int g_range;
> +	int ratio;
> +};
> +
> +static struct bma180_range bma180_range_table[7] = {
> +	{ 1000, 130 },
> +	{ 1500, 190 },
> +	{ 2000, 250 },
> +	{ 3000, 380 },
> +	{ 4000, 500 },
> +	{ 8000, 990 },
> +	{ 16000, 1980 },
> +};
> +
> +static int bma180_get_acc_reg(struct bma180_data *data, enum bma180_axis axis)
> +{
> +	u8 reg = BMA180_ACC_X_LSB + axis * 2;
> +	int ret;
> +
> +	if (data->sleep_state)
> +		return -EBUSY;
> +
> +	ret = i2c_smbus_read_word_data(data->client, reg);
> +	if (ret < 0)
> +		dev_err(&data->client->dev,
> +			"failed to read accel_%c registers\n", 'x' + axis);

just one register, not registers?

> +
> +	return ret;
> +}
> +
> +static int bma180_set_bits(struct bma180_data *data, u8 reg, u8 mask, u8 val)
> +{
> +	int ret = i2c_smbus_read_byte_data(data->client, reg);
> +	u8 reg_val = (ret & ~mask) | (val << (ffs(mask) - 1));
> +
> +	if (ret < 0)
> +		return ret;
> +
> +	return i2c_smbus_write_byte_data(data->client, reg, reg_val);
> +}
> +
> +static int bma180_set_new_data_intr_state(struct bma180_data *data, int state)
> +{
> +	u8 reg_val = state ? BMA180_NEW_DATA_INT : 0x00;
> +	int ret = i2c_smbus_write_byte_data(data->client, BMA180_CTRL_REG3,
> +			reg_val);
> +
> +	if (ret)
> +		dev_err(&data->client->dev,
> +			"failed to set new data interrupt state %d\n", state);
> +
> +	return ret;
> +}
> +
> +static int bma180_set_sleep_state(struct bma180_data *data, int state)
> +{
> +	int ret = bma180_set_bits(data, BMA180_CTRL_REG0, BMA180_SLEEP, state);
> +
> +	if (ret) {
> +		dev_err(&data->client->dev,
> +			"failed to set sleep state %d\n", state);
> +		return ret;
> +	}
> +	data->sleep_state = state;
> +
> +	return 0;
> +}
> +
> +static int bma180_set_ee_writing_state(struct bma180_data *data, int state)
> +{
> +	int ret = bma180_set_bits(data, BMA180_CTRL_REG0, BMA180_EE_W, state);
> +
> +	if (ret)
> +		dev_err(&data->client->dev,
> +			"failed to set ee writing state %d\n", state);
> +
> +	return ret;
> +}
> +
> +static int bma180_soft_reset(struct bma180_data *data)
> +{
> +	int ret = i2c_smbus_write_byte_data(data->client,
> +			BMA180_RESET, BMA180_RESET_VAL);
> +
> +	if (ret)
> +		dev_err(&data->client->dev, "failed to reset the chip\n");
> +
> +	return ret;
> +}
> +
> +static int bma180_chip_init(struct bma180_data *data)
> +{
> +	/* Try to read chip_id register. It must return 0x03. */
> +	int ret = i2c_smbus_read_byte_data(data->client, BMA180_CHIP_ID);
> +
> +	if (ret < 0)
> +		goto err;
> +	if (ret != 0x03) {
> +		ret = -ENODEV;
> +		goto err;
> +	}
> +
> +	ret = bma180_soft_reset(data);
> +	if (ret)
> +		goto err;
> +	/*
> +	 * No serial transaction should occur within minimum 10 μs
> +	 * after soft_reset command
> +	 */
> +	msleep(20);
> +
> +	ret = bma180_set_bits(data, BMA180_CTRL_REG0, BMA180_DIS_WAKE_UP, 1);
> +	if (ret)
> +		goto err;
> +	ret = bma180_set_ee_writing_state(data, 1);
> +	if (ret)
> +		goto err;
> +	ret = bma180_set_new_data_intr_state(data, 0);
> +	if (ret)
> +		goto err;
> +	ret = bma180_set_bits(data, BMA180_BW_TCS, BMA180_BW, data->bw);
> +	if (ret)
> +		goto err;
> +	ret = bma180_set_bits(data,
> +			BMA180_OFFSET_LSB1, BMA180_RANGE, data->range);
> +	if (ret)
> +		goto err;
> +	ret = bma180_set_bits(data, BMA180_TCO_Z, BMA180_MODE_CONFIG,
> +			data->mode ? BMA180_LOW_POWER : BMA180_LOW_NOISE);
> +	if (ret)
> +		goto err;
> +	ret = bma180_set_bits(data, BMA180_OFFSET_LSB1, BMA180_SMP_SKIP, 1);
> +	if (ret)
> +		goto err;
> +	ret = bma180_set_new_data_intr_state(data, 1);
> +	if (ret)
> +		goto err;
> +	ret = bma180_set_ee_writing_state(data, 0);
> +	if (ret)
> +		goto err;
> +
> +	return 0;
> +
> +err:
> +	dev_err(&data->client->dev, "failed to init the chip\n");
> +	return ret;
> +}
> +
> +static void bma180_chip_disable(struct bma180_data *data)
> +{
> +	if (bma180_set_ee_writing_state(data, 1))
> +		goto err;
> +	if (bma180_set_new_data_intr_state(data, 0))
> +		goto err;
> +	if (bma180_set_ee_writing_state(data, 0))
> +		goto err;
> +	if (bma180_set_sleep_state(data, 1))
> +		goto err;
> +
> +	return;
> +
> +err:
> +	dev_err(&data->client->dev, "failed to disable the chip\n");
> +}
> +
> +static int bma180_read_raw(struct iio_dev *indio_dev,
> +		struct iio_chan_spec const *chan, int *val, int *val2,
> +		long mask)
> +{
> +	struct bma180_data *data = iio_priv(indio_dev);
> +	long tmp = ((s16)data->acc_reg[chan->channel] >> 2)
> +		* bma180_range_table[data->range].ratio;
> +
> +	if (data->acc_reg[chan->channel] < 0)
> +		return data->acc_reg[chan->channel];
> +
> +	*val = tmp / 1000000;
> +	*val2 = (tmp % 1000000);
> +
> +	return IIO_VAL_INT_PLUS_MICRO;
> +}
> +
> +static const struct iio_info bma180_info = {
> +	.driver_module	= THIS_MODULE,
> +	.read_raw	= &bma180_read_raw,
> +};
> +
> +static const struct iio_chan_spec bma180_channels[] = {
> +	{
> +		.type = IIO_ACCEL,
> +		.channel = AXIS_X,
> +		.channel2 = IIO_MOD_X,
> +		.indexed = true,

do the channels need to be indexed?

> +		.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
> +	}, {
> +		.type = IIO_ACCEL,
> +		.channel = AXIS_Y,
> +		.channel2 = IIO_MOD_Y,
> +		.indexed = true,
> +		.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
> +	}, {
> +		.type = IIO_ACCEL,
> +		.channel = AXIS_Z,
> +		.channel2 = IIO_MOD_Z,
> +		.indexed = true,
> +		.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
> +	},
> +};
> +
> +static irqreturn_t bma180_interrupt_handler(int irq, void *private)
> +{
> +	struct iio_dev *dev_info = private;
> +	struct bma180_data *data = iio_priv(dev_info);
> +	int i;
> +
> +	mutex_lock(&data->mutex);
> +	for (i = AXIS_X; i <= AXIS_Z; ++i)
> +		data->acc_reg[i] = bma180_get_acc_reg(data, i);
> +	mutex_unlock(&data->mutex);
> +
> +	input_report_abs(data->input_dev, ABS_X, data->acc_reg[AXIS_X]);
> +	input_report_abs(data->input_dev, ABS_Y, data->acc_reg[AXIS_Y]);
> +	input_report_abs(data->input_dev, ABS_Z, data->acc_reg[AXIS_Z]);

input subsystem stuff within IIO?
uhoh...

the driver should probably support more iio features: trigger, scan_mode, 
buffer

> +	input_sync(data->input_dev);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +static int bma180_probe(struct i2c_client *client,
> +		const struct i2c_device_id *id)
> +{
> +	struct input_dev *input_dev;
> +	struct bma180_data *data;
> +	struct iio_dev *indio_dev;
> +	struct device_node *np = client->dev.of_node;
> +	int i, ret;
> +
> +	if (!client->irq) {
> +		dev_err(&client->dev, "this driver cann't work without IRQ\n");

can't

> +		return -ENODEV;
> +	}
> +
> +	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
> +	if (!indio_dev)
> +		return -ENOMEM;
> +
> +	input_dev = input_allocate_device();
> +	if (!input_dev)
> +		return -ENOMEM;
> +
> +	data = iio_priv(indio_dev);
> +	i2c_set_clientdata(client, indio_dev);
> +	data->client = client;
> +
> +	of_property_read_u32(np, "bw", &data->bw);
> +	of_property_read_u32(np, "range", &data->range);
> +	of_property_read_u32(np, "mode", &data->mode);
> +	of_property_read_u32(np, "fuzz", &data->fuzz);
> +
> +	ret = bma180_chip_init(data);
> +	if (ret < 0)
> +		goto err_1;
> +
> +	mutex_init(&data->mutex);
> +
> +	indio_dev->dev.parent = &client->dev;
> +	indio_dev->channels = bma180_channels;
> +	indio_dev->num_channels = ARRAY_SIZE(bma180_channels);
> +	indio_dev->name = BMA180_DRV_NAME;
> +	indio_dev->modes = INDIO_DIRECT_MODE;
> +	indio_dev->info = &bma180_info;
> +
> +	input_dev->name = BMA180_DRV_NAME;
> +	input_dev->id.bustype = BUS_I2C;
> +	__set_bit(EV_ABS, input_dev->evbit);
> +	for (i = ABS_X; i <= ABS_Z; ++i)
> +		input_set_abs_params(input_dev, i,
> +				     -bma180_range_table[data->range].g_range,
> +				     bma180_range_table[data->range].g_range,
> +				     data->fuzz, 0);
> +	input_dev->dev.parent = &client->dev;
> +	input_set_drvdata(input_dev, data);
> +
> +	data->input_dev = input_dev;
> +
> +	ret = devm_request_threaded_irq(&client->dev, client->irq,
> +			NULL, bma180_interrupt_handler, IRQF_ONESHOT,
> +			BMA180_IRQ_NAME, indio_dev);
> +	if (ret < 0) {
> +		dev_err(&client->dev, "irq request error %d\n", -ret);
> +		goto err_1;
> +	}
> +
> +	ret = input_register_device(input_dev);
> +	if (ret) {
> +		dev_err(&client->dev, "unable to register input device\n");
> +		goto err_1;
> +	}
> +
> +

extra newline

> +	ret = iio_device_register(indio_dev);
> +	if (ret < 0) {
> +		dev_err(&client->dev, "unable to register iio device\n");
> +		goto err_2;
> +	}
> +
> +	return 0;
> +
> +err_2:
> +	input_unregister_device(input_dev);
> +err_1:
> +	input_free_device(input_dev);
> +
> +	bma180_chip_disable(data);
> +
> +	return ret;
> +}
> +
> +static int bma180_remove(struct i2c_client *client)
> +{
> +	struct iio_dev *indio_dev = i2c_get_clientdata(client);
> +	struct bma180_data *data = iio_priv(indio_dev);
> +
> +	iio_device_unregister(indio_dev);
> +	input_unregister_device(data->input_dev);
> +
> +	mutex_lock(&data->mutex);
> +	bma180_chip_disable(data);
> +	mutex_unlock(&data->mutex);
> +
> +	return 0;
> +}
> +
> +#ifdef CONFIG_PM_SLEEP
> +static int bma180_suspend(struct device *dev)
> +{
> +	struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
> +	struct bma180_data *data = iio_priv(indio_dev);
> +	int ret;
> +
> +	mutex_lock(&data->mutex);
> +	ret = bma180_set_sleep_state(data, 1);
> +	mutex_unlock(&data->mutex);
> +
> +	return ret;
> +}
> +
> +static int bma180_resume(struct device *dev)
> +{
> +	struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
> +	struct bma180_data *data = iio_priv(indio_dev);
> +	int ret;
> +
> +	mutex_lock(&data->mutex);
> +	ret = bma180_set_sleep_state(data, 0);
> +	mutex_unlock(&data->mutex);
> +
> +	return ret;
> +}
> +
> +static SIMPLE_DEV_PM_OPS(bma180_pm_ops, bma180_suspend, bma180_resume);
> +#define BMA180_PM_OPS (&bma180_pm_ops)
> +#else
> +#define BMA180_PM_OPS NULL
> +#endif
> +
> +static struct i2c_device_id bma180_id[] = {
> +	{ BMA180_DRV_NAME, 0 },
> +	{ }
> +};
> +
> +MODULE_DEVICE_TABLE(i2c, bma180_id);
> +
> +static struct i2c_driver bma180_driver = {
> +	.driver = {
> +		.name	= BMA180_DRV_NAME,
> +		.owner	= THIS_MODULE,
> +		.pm	= BMA180_PM_OPS,
> +	},
> +	.probe		= bma180_probe,
> +	.remove		= bma180_remove,
> +	.id_table	= bma180_id,
> +};
> +
> +module_i2c_driver(bma180_driver);
> +
> +MODULE_AUTHOR("Kravchenko Oleksandr <x0199363@...com>");
> +MODULE_AUTHOR("Texas Instruments, Inc.");
> +MODULE_DESCRIPTION("Bosch BMA180 triaxial acceleration sensor");
> +MODULE_LICENSE("GPL");
> 

-- 

Peter Meerwald
+43-664-2444418 (mobile)

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