Re: [PATCH] iio: ms5637: Add Measurement Specialties MS5637 support

[Peter Meerwald <pmeerw@pmeerw.net>]

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> MS5637 spec : http://www.meas-spec.com/product/pressure/MS5637-02BA03.aspx

> Thank you in advance for reviewing again.

some comments below

> Signed-off-by: Ludovic <ludovic.tancerel@maplehightech.com>
> ---
>  drivers/iio/pressure/Kconfig  |  10 +
>  drivers/iio/pressure/Makefile |   1 +
>  drivers/iio/pressure/ms5637.c | 475 ++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 486 insertions(+)
>  create mode 100644 drivers/iio/pressure/ms5637.c
> 
> diff --git a/drivers/iio/pressure/Kconfig b/drivers/iio/pressure/Kconfig
> index a3be537..6c7faa1 100644
> --- a/drivers/iio/pressure/Kconfig
> +++ b/drivers/iio/pressure/Kconfig
> @@ -52,6 +52,16 @@ config MPL3115
>            To compile this driver as a module, choose M here: the module
>            will be called mpl3115.
>  
> +config MS5637
> +        tristate "MS5637 pressure & temperature sensor"
> +        depends on I2C
> +        help
> +          If you say yes here you get support for the Measurement Specialties
> +          MS5637 pressure and temperature sensor.
> +
> +          This driver can also be built as a module. If so, the module will
> +          be called ms5637.
> +
>  config IIO_ST_PRESS
>  	tristate "STMicroelectronics pressure sensor Driver"
>  	depends on (I2C || SPI_MASTER) && SYSFS
> diff --git a/drivers/iio/pressure/Makefile b/drivers/iio/pressure/Makefile
> index 88011f2..2455f8e 100644
> --- a/drivers/iio/pressure/Makefile
> +++ b/drivers/iio/pressure/Makefile
> @@ -7,6 +7,7 @@ obj-$(CONFIG_BMP280) += bmp280.o
>  obj-$(CONFIG_HID_SENSOR_PRESS)   += hid-sensor-press.o
>  obj-$(CONFIG_MPL115) += mpl115.o
>  obj-$(CONFIG_MPL3115) += mpl3115.o
> +obj-$(CONFIG_MS5637) += ms5637.o
>  obj-$(CONFIG_IIO_ST_PRESS) += st_pressure.o
>  st_pressure-y := st_pressure_core.o
>  st_pressure-$(CONFIG_IIO_BUFFER) += st_pressure_buffer.o
> diff --git a/drivers/iio/pressure/ms5637.c b/drivers/iio/pressure/ms5637.c
> new file mode 100644
> index 0000000..9c647d7
> --- /dev/null
> +++ b/drivers/iio/pressure/ms5637.c
> @@ -0,0 +1,475 @@
> +/*
> + * ms5637.c - Support for Measurement-Specialties ms5637
> + *            pressure & temperature sensor
> + *
> + * Copyright (c) 2014 Measurement-Specialties
> + *
> + * Licensed under the GPL-2.
> + *
> + * (7-bit I2C slave address 0x76)
> + *
> + */
> +#include <linux/init.h>
> +#include <linux/device.h>
> +#include <linux/kernel.h>
> +#include <linux/stat.h>
> +#include <linux/module.h>
> +#include <linux/i2c.h>
> +#include <linux/iio/iio.h>
> +#include <linux/iio/sysfs.h>
> +#include <linux/jiffies.h>
> +#include <linux/delay.h>
> +#include <linux/mutex.h>
> +
> +/* MS5637 Commands */
> +#define MS5637_RESET				0x1E
> +#define MS5637_TEMPERATURE_CONVERSION_START	0x50
> +#define MS5637_PRESSURE_CONVERSION_START	0x40
> +#define MS5637_ADC_READ				0x00
> +#define MS5637_PROM_READ			0xA0
> +#define MS5637_PROM_ELEMENTS_NB                 7
> +
> +static const u16 ms5637_conversion_time[] = { 1000, 2000, 3000,
> +					      5000, 9000, 17000 };
> +static const int ms5637_samp_freq[6][2] = { {1800, 0}, {900, 0},
> +					    {450, 0}, {225, 0},
> +					    {112, 500000}, {56, 250000},
> +					  };
> +
> +struct ms5637_dev {
> +	struct i2c_client *client;
> +	struct mutex lock; /* mutex protecting this data structure */
> +	u16 calibration_coeffs[MS5637_PROM_ELEMENTS_NB];
> +	bool got_calibration_words;
> +	unsigned long last_update;
> +	bool valid;
> +	int temperature;
> +	unsigned int pressure;
> +	u8 resolution_index;
> +};
> +
> +static int ms5637_get_calibration_coeffs(struct ms5637_dev *dev_data,
> +					 unsigned char index, u16 *word)

u8 index probably

> +{
> +	int ret = 0;

initialization not necessary

> +
> +	ret = i2c_smbus_read_word_swapped(dev_data->client,
> +					  MS5637_PROM_READ + (index << 1));
> +	if (ret < 0)
> +		return ret;
> +	*word = (u16)ret & 0xFFFF;

*word = ret; should do as well

> +	return 0;
> +}
> +
> +static bool ms5637_crc_check(u16 *n_prom, u8 crc)
> +{
> +	unsigned int cnt, n_bit;
> +	u16 n_rem, crc_read;
> +
> +	n_rem = 0x0000;
> +	crc_read = n_prom[0];
> +	n_prom[MS5637_PROM_ELEMENTS_NB] = 0;

this looks like an out-of-bound access, one beyond 
calibration_coeffs[MS5637_PROM_ELEMENTS_NB]

> +	n_prom[0] &= 0x0FFF;	/* Clear the CRC byte */

better a space instead of a tab to separate comment;
0x0fff is not a byte, the comment is misleading

> +
> +	for (cnt = 0; cnt < (MS5637_PROM_ELEMENTS_NB + 1) * 2; cnt++) {

probably also out-of-bound

> +		if (cnt % 2 == 1)
> +			n_rem ^= n_prom[cnt >> 1] & 0x00FF;
> +		else
> +			n_rem ^= n_prom[cnt >> 1] >> 8;
> +
> +		for (n_bit = 8; n_bit > 0; n_bit--) {
> +			if (n_rem & 0x8000)
> +				n_rem = (n_rem << 1) ^ 0x3000;
> +			else
> +				n_rem <<= 1;
> +		}
> +	}
> +	n_rem >>= 12;
> +	n_prom[0] = crc_read;
> +	return (n_rem == crc);

() is not necessary

> +}
> +
> +static int ms5637_fill_calibration_coeffs(struct ms5637_dev *dev_data)
> +{
> +	int i, ret = 0;

init of ret not necessary
> +
> +	for (i = 0; i < MS5637_PROM_ELEMENTS_NB; i++) {
> +		ret = ms5637_get_calibration_coeffs(
> +					dev_data, i,
> +					&dev_data->calibration_coeffs[i]);
> +
> +		if (ret < 0) {
> +			dev_err(&dev_data->client->dev,
> +				"Unable to get calibration coefficients at address %d\n",
> +				i + 1);
> +			return ret;
> +		}
> +
> +		dev_dbg(&dev_data->client->dev, "Coeff %d : %d", i,
> +			dev_data->calibration_coeffs[i]);
> +	}
> +
> +	ret = ms5637_crc_check(
> +			dev_data->calibration_coeffs,
> +			(dev_data->calibration_coeffs[0] & 0xF000) >> 12);

_crc_check() returns bool, so check for == false

> +	if (ret == 0)
> +		dev_err(&dev_data->client->dev,
> +			"Calibration coefficients crc check error\n");
> +
> +	return 0;
> +}
> +
> +static int ms5637_read_adc_value(struct ms5637_dev *dev_data, u32 *adc_value)
> +{
> +	int ret;
> +	u8 buf[3];
> +
> +	ret =
> +	    i2c_smbus_read_i2c_block_data(dev_data->client, MS5637_ADC_READ, 3,
> +					  buf);
> +	if (ret < 0)
> +		return ret;
> +	dev_dbg(&dev_data->client->dev, "ADC raw value : %x %x %x\n", buf[0],
> +		buf[1], buf[2]);

probably some whitespace here...

> +	*adc_value = (buf[0] << 16) + (buf[1] << 8) + buf[2];

.. and here

> +	return 0;
> +}
> +
> +static int ms5637_conversion_and_read_adc(struct ms5637_dev *dev_data,
> +					  u32 *t_adc, u32 *p_adc)
> +{
> +	int ret;
> +
> +	dev_dbg(&dev_data->client->dev, "ms5637_conversion_and_read_adc");
> +	/* Trigger Temperature conversion */
> +	ret = i2c_smbus_write_byte(dev_data->client,
> +				   MS5637_TEMPERATURE_CONVERSION_START
> +				   + dev_data->resolution_index * 2);
> +	if (ret < 0)
> +		return ret;
> +	usleep_range(ms5637_conversion_time[dev_data->resolution_index],
> +		     ms5637_conversion_time[dev_data->resolution_index] + 3000);

maybe a MACRO() for this monster?

> +	/* Retrieve ADC value */
> +	ret = ms5637_read_adc_value(dev_data, t_adc);
> +	if (ret < 0)
> +		return ret;
> +
> +	/* Trigger Pressure conversion */
> +	ret = i2c_smbus_write_byte(dev_data->client,
> +				   MS5637_PRESSURE_CONVERSION_START
> +				   + dev_data->resolution_index * 2);
> +	if (ret < 0)
> +		return ret;
> +	usleep_range(ms5637_conversion_time[dev_data->resolution_index],
> +		     ms5637_conversion_time[dev_data->resolution_index] + 3000);
> +	/* Retrieve ADC value */
> +	ret = ms5637_read_adc_value(dev_data, p_adc);
> +	if (ret < 0)
> +		return ret;
> +
> +	return 0;
> +}
> +
> +static int ms5637_read_temperature_and_pressure(struct ms5637_dev *dev_data)
> +{
> +	int ret = 0;
> +	u32 t_adc, p_adc;
> +	s32 dt, temp;
> +	s64 off, sens, t2, off2, sens2;
> +
> +	mutex_lock(&dev_data->lock);
> +
> +	if (time_after(jiffies, dev_data->last_update + HZ / 2) ||
> +	    !dev_data->valid) {
> +		if (!dev_data->got_calibration_words) {
> +			ret = ms5637_fill_calibration_coeffs(dev_data);
> +			if (ret != 0)
> +				goto out;
> +
> +			dev_data->got_calibration_words = true;
> +		}
> +
> +		ret = ms5637_conversion_and_read_adc(dev_data, &t_adc, &p_adc);
> +		if (ret < 0) {
> +			dev_data->got_calibration_words = false;
> +			dev_err(&dev_data->client->dev,
> +				"Unable to make sensor adc conversion\n");
> +			goto out;
> +		}
> +
> +		dt = (s32)t_adc - (dev_data->calibration_coeffs[5] << 8);
> +
> +		/* Actual temperature = 2000 + dT * TEMPSENS */
> +		temp =
> +		    2000 + (((s64)dt * dev_data->calibration_coeffs[6]) >> 23);
> +
> +		/* Second order temperature compensation */
> +		if (temp < 2000) {
> +			s64 tmp = (s64)temp - 2000;
> +
> +			t2 = (3 * ((s64)dt * (s64)dt)) >> 33;
> +			off2 = (61 * tmp * tmp) >> 4;
> +			sens2 = (29 * tmp * tmp) >> 4;
> +
> +			if (temp < -1500) {
> +				s64 tmp = (s64)temp + 1500;
> +
> +				off2 += 17 * tmp * tmp;
> +				sens2 += 9 * tmp * tmp;
> +			}
> +		} else {
> +			t2 = (5 * ((s64)dt * (s64)dt)) >> 38;
> +			off2 = 0;
> +			sens2 = 0;
> +		}
> +
> +		/* OFF = OFF_T1 + TCO * dT */
> +		off = (((s64)dev_data->calibration_coeffs[2]) << 17) +
> +		    ((((s64)dev_data->calibration_coeffs[4]) * (s64)dt) >> 6);
> +		off -= off2;
> +
> +		/* Sensitivity at actual temperature = SENS_T1 + TCS * dT */
> +		sens = (((s64)dev_data->calibration_coeffs[1]) << 16)
> +		    + (((s64)dev_data->calibration_coeffs[3] * dt) >> 7);
> +		sens -= sens2;
> +
> +		/* Temperature compensated pressure = D1 * SENS - OFF */
> +		dev_data->temperature = (temp - t2) * 10;
> +		dev_data->pressure = (u32)(((((s64)p_adc * sens) >> 21)
> +					     - off) >> 15);
> +
> +		dev_data->last_update = jiffies;
> +		dev_data->valid = true;
> +	}
> + out:
> +	mutex_unlock(&dev_data->lock);
> +
> +	return ret >= 0 ? 0 : ret;
> +}
> +
> +static int ms5637_get_int_plus_micros_index(const int (*vals)[2], int n,
> +					    int val, int val2)
> +{
> +	while (n-- > 0)
> +		if (val == vals[n][0] && val2 == vals[n][1])
> +			return n;
> +	return -EINVAL;
> +}
> +
> +static int ms5637_get_samp_freq_index(struct ms5637_dev *dev_data,
> +				      int val, int val2)
> +{
> +	return ms5637_get_int_plus_micros_index(ms5637_samp_freq,
> +				ARRAY_SIZE(ms5637_samp_freq), val, val2);
> +}
> +
> +static ssize_t ms5637_show_int_plus_micros(char *buf,
> +					   const int (*vals)[2], int n)
> +{
> +	size_t len = 0;
> +
> +	while (n-- > 0)
> +		len += scnprintf(buf + len, PAGE_SIZE - len,
> +			"%d.%06d ", vals[n][0], vals[n][1]);
> +
> +	/* replace trailing space by newline */
> +	buf[len - 1] = '\n';
> +
> +	return len;
> +}
> +
> +static ssize_t ms5637_show_samp_freq_avail(struct device *dev,
> +					   struct device_attribute *attr,
> +					   char *buf)
> +{
> +	return ms5637_show_int_plus_micros(buf, ms5637_samp_freq,
> +					   ARRAY_SIZE(ms5637_samp_freq));
> +}
> +
> +static int ms5637_read_raw(struct iio_dev *indio_dev,
> +			   struct iio_chan_spec const *channel, int *val,
> +			   int *val2, long mask)
> +{
> +	int ret;
> +	struct ms5637_dev *dev_data = iio_priv(indio_dev);
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_PROCESSED:
> +		ret = ms5637_read_temperature_and_pressure(dev_data);
> +		if (ret)
> +			goto err;
> +		switch (channel->type) {
> +		case IIO_TEMP:	/* in °C */
> +			*val = dev_data->temperature / 1000;
> +			*val2 = (dev_data->temperature -
> +					(dev_data->temperature / 1000) * 1000
> +				) * 1000;

maybe a function/macro for splitting up the data?

> +			break;
> +		case IIO_PRESSURE:	/* in kPa */
> +			*val = dev_data->pressure / 1000;
> +			*val2 = (dev_data->pressure -
> +				 (dev_data->pressure / 1000) * 1000) * 1000;
> +			break;
> +		default:
> +			return -EINVAL;
> +		}
> +		break;
> +	case IIO_CHAN_INFO_SAMP_FREQ:
> +		*val = ms5637_samp_freq[dev_data->resolution_index][0];
> +		*val2 = ms5637_samp_freq[dev_data->resolution_index][1];
> +		break;
> +	default:
> +		return -EINVAL;
> +	}
> +
> +	return IIO_VAL_INT_PLUS_MICRO;
> + err:
> +	dev_err(&indio_dev->dev, "Device read error\n");
> +	return ret;
> +}
> +
> +static int ms5637_write_raw(struct iio_dev *indio_dev,
> +			    struct iio_chan_spec const *chan,
> +			    int val, int val2, long mask)
> +{
> +	struct ms5637_dev *dev_data = iio_priv(indio_dev);
> +	int i;
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_SAMP_FREQ:
> +		i = ms5637_get_samp_freq_index(dev_data, val, val2);
> +		if (i < 0)
> +			return -EINVAL;
> +
> +		dev_data->resolution_index = i;
> +		break;

perhaps return 0 here

> +	default:
> +		return -EINVAL;
> +	}
> +	return 0;
> +}
> +
> +static const struct iio_chan_spec ms5637_channels[] = {
> +	{
> +	 .type = IIO_TEMP,
> +	 .info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
> +	 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SAMP_FREQ),
> +	 },
> +	{
> +	 .type = IIO_PRESSURE,
> +	 .info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
> +	 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SAMP_FREQ),
> +	 }
> +};
> +
> +static IIO_DEV_ATTR_SAMP_FREQ_AVAIL(ms5637_show_samp_freq_avail);
> +
> +static struct attribute *ms5637_attributes[] = {
> +	&iio_dev_attr_sampling_frequency_available.dev_attr.attr,
> +	NULL,
> +};
> +
> +static const struct attribute_group ms5637_attribute_group = {
> +	.attrs = ms5637_attributes,
> +};
> +
> +static const struct iio_info ms5637_info = {
> +	.read_raw = ms5637_read_raw,
> +	.write_raw = ms5637_write_raw,
> +	.attrs = &ms5637_attribute_group,
> +	.driver_module = THIS_MODULE,
> +};
> +
> +static int ms5637_probe(struct i2c_client *client,
> +			const struct i2c_device_id *id)
> +{
> +	struct ms5637_dev *dev_data;
> +	struct iio_dev *indio_dev;
> +	int ret;
> +
> +	if (!i2c_check_functionality(client->adapter,
> +				     I2C_FUNC_SMBUS_READ_WORD_DATA)) {
> +		dev_err(&client->dev,
> +			"Adapter does not support SMBus read word transactions\n");
> +		return -ENODEV;
> +	}
> +
> +	if (!i2c_check_functionality(client->adapter,
> +				     I2C_FUNC_SMBUS_WRITE_BYTE)) {
> +		dev_err(&client->dev,
> +			"Adapter does not support SMBus write byte transactions\n");
> +		return -ENODEV;
> +	}
> +
> +	if (!i2c_check_functionality(client->adapter,
> +				     I2C_FUNC_SMBUS_READ_I2C_BLOCK)) {
> +		dev_err(&client->dev,
> +			"Adapter does not support SMBus read block transactions\n");
> +		return -ENODEV;
> +	}
> +
> +	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*dev_data));
> +	if (!indio_dev)
> +		return -ENOMEM;
> +
> +	dev_data = iio_priv(indio_dev);
> +	dev_data->client = client;
> +	mutex_init(&dev_data->lock);
> +
> +	indio_dev->info = &ms5637_info;
> +	indio_dev->name = id->name;
> +	indio_dev->dev.parent = &client->dev;
> +	indio_dev->modes = INDIO_DIRECT_MODE;
> +	indio_dev->channels = ms5637_channels;
> +	indio_dev->num_channels = ARRAY_SIZE(ms5637_channels);
> +
> +	i2c_set_clientdata(client, indio_dev);
> +	ret = i2c_smbus_write_byte(client, MS5637_RESET);
> +	if (ret < 0)
> +		return ret;
> +	usleep_range(3000, 6000);
> +
> +	ret = ms5637_fill_calibration_coeffs(dev_data);
> +	if (ret == 0)

probably return ret on error 

> +		dev_data->got_calibration_words = true;

and move 
dev_data->got_calibration_words = true
to fill_calib_coeffs(), would save another assignment elsewhere also

> +	else
> +		return ret;
> +
> +	ret = iio_device_register(indio_dev);
> +	if (ret < 0)
> +		return ret;
> +
> +	dev_dbg(&client->dev, "Driver initialization done");
> +	return 0;
> +}
> +
> +static int ms5637_remove(struct i2c_client *client)
> +{
> +	struct iio_dev *indio_dev = i2c_get_clientdata(client);
> +
> +	devm_iio_device_unregister(&client->dev, indio_dev);

iio_device_register() vs. devm_iio_device_unregister -- really?

perhaps this could be one of the cases where we can 
devm_iio_device_register() and just drop the _remove()?

> +
> +	return 0;
> +}
> +
> +static const struct i2c_device_id ms5637_id[] = {
> +	{"ms5637", 0},
> +	{}
> +};
> +
> +static struct i2c_driver ms5637_driver = {
> +	.probe = ms5637_probe,
> +	.remove = ms5637_remove,
> +	.id_table = ms5637_id,
> +	.driver = {
> +		   .name = "ms5637",
> +		   .owner = THIS_MODULE,
> +		   },
> +};
> +
> +module_i2c_driver(ms5637_driver);
> +
> +MODULE_LICENSE("GPL");
> +MODULE_DESCRIPTION("Measurement-Specialties ms5637 temperature driver");

and pressure

> +MODULE_AUTHOR("William Markezana <william.markezana@meas-spec.com>");
> +MODULE_AUTHOR("Ludovic Tancerel <ludovic.tancerel@maplehightech.com>");
> 

-- 

Peter Meerwald
+43-664-2444418 (mobile)