Re: [PATCH v2 3/3] iio: humidity: si7020: added No Hold read mode

[Jonathan Cameron <jic23@kernel.org>]

On 16/09/15 14:35, Nicola Corna wrote:
> The Si7013/20/21 modules support 2 read modes:
>  * Hold mode (blocking), where the device stretches the clock until the end
> of the measurement
>  * No Hold mode (non-blocking), where the device replies NACK for every I2C
> call during the measurement
> Here the No Hold mode is implemented, selectable with the blocking_io
> variable within si7020_platform_data. The default mode is Hold, unless the
> adapter does not support clock stretching, in which case the No Hold mode
> is used.
> 
> Signed-off-by: Nicola Corna <nicola@corna.info>
Acked-by: Jonathan Cameron <jic23@kernel.org>

Wolfram, I'm guessing you will pick these up via the i2c tree when
he is happy with them.   If you want me to take the series through IIO
let me know.

Thanks,

Jonathan
> ---
> This patch depends on patch "[PATCH v4 1/2] iio: humidity: si7020: replaced
> bitmask on humidity values with range check"
>  drivers/iio/humidity/si7020.c        | 76 ++++++++++++++++++++++++++++++++----
>  include/linux/platform_data/si7020.h | 21 ++++++++++
>  2 files changed, 90 insertions(+), 7 deletions(-)
>  create mode 100644 include/linux/platform_data/si7020.h
> 
> diff --git a/drivers/iio/humidity/si7020.c b/drivers/iio/humidity/si7020.c
> index 12128d1..9cf9527 100644
> --- a/drivers/iio/humidity/si7020.c
> +++ b/drivers/iio/humidity/si7020.c
> @@ -2,6 +2,7 @@
>   * si7020.c - Silicon Labs Si7013/20/21 Relative Humidity and Temp Sensors
>   * Copyright (c) 2013,2014  Uplogix, Inc.
>   * David Barksdale <dbarksdale@uplogix.com>
> + * Copyright (c) 2015 Nicola Corna <nicola@corna.info>
>   *
>   * This program is free software; you can redistribute it and/or modify it
>   * under the terms and conditions of the GNU General Public License,
> @@ -30,33 +31,78 @@
>  #include <linux/module.h>
>  #include <linux/slab.h>
>  #include <linux/sysfs.h>
> +#include <linux/jiffies.h>
>  
>  #include <linux/iio/iio.h>
>  #include <linux/iio/sysfs.h>
> +#include <linux/platform_data/si7020.h>
>  
>  /* Measure Relative Humidity, Hold Master Mode */
>  #define SI7020CMD_RH_HOLD	0xE5
> +/* Measure Relative Humidity, No Hold Master Mode */
> +#define SI7020CMD_RH_NO_HOLD	0xF5
>  /* Measure Temperature, Hold Master Mode */
>  #define SI7020CMD_TEMP_HOLD	0xE3
> +/* Measure Temperature, No Hold Master Mode */
> +#define SI7020CMD_TEMP_NO_HOLD	0xF3
>  /* Software Reset */
>  #define SI7020CMD_RESET		0xFE
> +/* Relative humidity measurement timeout (us) */
> +#define SI7020_RH_TIMEOUT	22800
> +/* Temperature measurement timeout (us) */
> +#define SI7020_TEMP_TIMEOUT	10800
> +/* Minimum delay between retries (No Hold Mode) in us */
> +#define SI7020_NOHOLD_SLEEP_MIN	2000
> +/* Maximum delay between retries (No Hold Mode) in us */
> +#define SI7020_NOHOLD_SLEEP_MAX	6000
>  
>  static int si7020_read_raw(struct iio_dev *indio_dev,
>  			   struct iio_chan_spec const *chan, int *val,
>  			   int *val2, long mask)
>  {
>  	struct i2c_client **client = iio_priv(indio_dev);
> +	struct si7020_platform_data *pdata;
>  	int ret;
> +	bool holdmode;
> +	unsigned char buf[2];
> +	unsigned long start;
>  
>  	switch (mask) {
>  	case IIO_CHAN_INFO_RAW:
> -		ret = i2c_smbus_read_word_data(*client,
> -					       chan->type == IIO_TEMP ?
> -					       SI7020CMD_TEMP_HOLD :
> -					       SI7020CMD_RH_HOLD);
> -		if (ret < 0)
> -			return ret;
> -		*val = ret >> 2;
> +		pdata = dev_get_platdata(&(*client)->dev);
> +		if (pdata)
> +			holdmode = pdata->blocking_io;
> +		else
> +			holdmode = !i2c_check_functionality((*client)->adapter,
> +						I2C_FUNC_NO_CLK_STRETCH);
> +		if (holdmode) {
> +			ret = i2c_smbus_read_word_data(*client,
> +						       chan->type == IIO_TEMP ?
> +						       SI7020CMD_TEMP_HOLD :
> +						       SI7020CMD_RH_HOLD);
> +			if (ret < 0)
> +				return ret;
> +			*val = ret >> 2;
> +		} else {
> +			ret = i2c_smbus_write_byte(*client,
> +						   chan->type == IIO_TEMP ?
> +						   SI7020CMD_TEMP_NO_HOLD :
> +						   SI7020CMD_RH_NO_HOLD);
> +			if (ret < 0)
> +				return ret;
> +			start = jiffies;
> +			while ((ret = i2c_master_recv(*client, buf, 2)) < 0) {
> +				if (time_after(jiffies, start +
> +					       usecs_to_jiffies(
> +							chan->type == IIO_TEMP ?
> +							SI7020_TEMP_TIMEOUT :
> +							SI7020_RH_TIMEOUT)))
> +					return ret;
> +				usleep_range(SI7020_NOHOLD_SLEEP_MIN,
> +					     SI7020_NOHOLD_SLEEP_MAX);
> +			}
> +			*val = ((buf[0] << 8) | buf[1]) >> 2;
> +		}
>  		/*
>  		 * Humidity values can slightly exceed the 0-100%RH
>  		 * range and should be corrected by software
> @@ -116,6 +162,7 @@ static int si7020_probe(struct i2c_client *client,
>  {
>  	struct iio_dev *indio_dev;
>  	struct i2c_client **data;
> +	struct si7020_platform_data *pdata;
>  	int ret;
>  
>  	if (!i2c_check_functionality(client->adapter,
> @@ -123,6 +170,21 @@ static int si7020_probe(struct i2c_client *client,
>  				     I2C_FUNC_SMBUS_READ_WORD_DATA))
>  		return -ENODEV;
>  
> +	pdata = dev_get_platdata(&client->dev);
> +	if (pdata) {
> +		if (pdata->blocking_io) {
> +			if (i2c_check_functionality(client->adapter,
> +						    I2C_FUNC_NO_CLK_STRETCH))
> +				return -ENODEV;
> +		} else if (!i2c_check_functionality(client->adapter,
> +								I2C_FUNC_I2C))
> +			return -ENODEV;
> +	} else
> +		if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C) &&
> +		   i2c_check_functionality(client->adapter,
> +					   I2C_FUNC_NO_CLK_STRETCH))
> +			return -ENODEV;
> +
>  	/* Reset device, loads default settings. */
>  	ret = i2c_smbus_write_byte(client, SI7020CMD_RESET);
>  	if (ret < 0)
> diff --git a/include/linux/platform_data/si7020.h b/include/linux/platform_data/si7020.h
> new file mode 100644
> index 0000000..8bb5848
> --- /dev/null
> +++ b/include/linux/platform_data/si7020.h
> @@ -0,0 +1,21 @@
> +/*
> + * Copyright (C) 2015 Nicola Corna <nicola@corna.info>
> + *
> + * This software is licensed under the terms of the GNU General Public
> + * License version 2, as published by the Free Software Foundation, and
> + * may be copied, distributed, and modified under those terms.
> + *
> + * This program is distributed in the hope that 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.
> + *
> + */
> +
> +#ifndef __SI7020_H_
> +#define __SI7020_H_
> +
> +struct si7020_platform_data {
> +	bool blocking_io;
> +};
> +#endif /* __SI7020_H_ */
>