[PATCH v5 5/5] iio: humidity: si7020: add No Hold read mode

Jonathan Cameron
2015-10-31T10:21:56Z

On 29/10/15 11:34, 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>
I'm fine with this. The dependency below should I think show up in the
coming merge window, so this lot might as well go via Wolfram.

Acked-by: Jonathan Cameron <jic23@kernel.org>
> ---
> 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 | 75 ++++++++++++++++++++++++++++++++----
> include/linux/platform_data/si7020.h | 21 ++++++++++
> 2 files changed, 89 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..674a61a 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_quirks((*client)->adapter,
> + I2C_AQ_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 +170,20 @@ 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_quirks(client->adapter,
> + I2C_AQ_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_quirks(client->adapter, I2C_AQ_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_ */
>