Re: [PATCH v3 3/8] drivers:input:tsc2007: add iio interface to read external ADC input, temperature and raw conversion values

[Jonathan Cameron <jic23-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>]

On 23/09/16 13:41, H. Nikolaus Schaller wrote:
> The tsc2007 chip not only has a resistive touch screen controller but
> also an external AUX adc imput which can be used for an ambient
> light sensor, battery voltage monitoring or any general purpose.
> 
> Additionally it can measure the chip temperature.
> 
> This extension provides an iio interface for these adc channels
> in addition to the raw x, y, z values and the estimated touch
> screen resistance. This can be used for debugging or special
> applications.
I'm unconvinced that exposing the touch related channels is terribly
useful.  Fair enough on the aux channel and temperature though.

Otherwise a few minor bits and bobs.

Jonathan
> 
> Signed-off-by: H. Nikolaus Schaller <hns-xXXSsgcRVICgSpxsJD1C4w@public.gmane.org>
> ---
>  drivers/input/touchscreen/Kconfig   |   1 +
>  drivers/input/touchscreen/tsc2007.c | 137 +++++++++++++++++++++++++++++++++++-
>  2 files changed, 136 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/input/touchscreen/Kconfig b/drivers/input/touchscreen/Kconfig
> index 2fb1f43..84c28e8 100644
> --- a/drivers/input/touchscreen/Kconfig
> +++ b/drivers/input/touchscreen/Kconfig
> @@ -1019,6 +1019,7 @@ config TOUCHSCREEN_TSC2005
>  config TOUCHSCREEN_TSC2007
>  	tristate "TSC2007 based touchscreens"
>  	depends on I2C
> +	select IIO
This is pulling quite a bit of core IIO code in for a feature a lot
of users of this chip won't care about...
>  	help
>  	  Say Y here if you have a TSC2007 based touchscreen.
>  
> diff --git a/drivers/input/touchscreen/tsc2007.c b/drivers/input/touchscreen/tsc2007.c
> index e9d5086..559cbc6 100644
> --- a/drivers/input/touchscreen/tsc2007.c
> +++ b/drivers/input/touchscreen/tsc2007.c
> @@ -30,6 +30,9 @@
>  #include <linux/of.h>
>  #include <linux/of_gpio.h>
>  #include <linux/input/touchscreen.h>
> +#include <linux/iio/iio.h>
> +#include <linux/iio/machine.h>
Why machine.h? (or driver.h for that reason).

> +#include <linux/iio/driver.h>
>  
>  #define TSC2007_MEASURE_TEMP0		(0x0 << 4)
>  #define TSC2007_MEASURE_AUX		(0x2 << 4)
> @@ -61,6 +64,16 @@
>  #define READ_X		(ADC_ON_12BIT | TSC2007_MEASURE_X)
>  #define PWRDOWN		(TSC2007_12BIT | TSC2007_POWER_OFF_IRQ_EN)
>  
> +#define TSC2007_CHAN_IIO(_chan, _name, _type, _chan_info) \
> +{ \
> +	.datasheet_name = _name, \
> +	.type = _type, \
> +	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |	\
> +			BIT(_chan_info), \
> +	.indexed = 1, \
> +	.channel = _chan, \
> +}
> +
>  struct ts_event {
>  	u16	x;
>  	u16	y;
> @@ -69,9 +82,11 @@ struct ts_event {
>  
>  struct tsc2007 {
>  	struct input_dev	*input;
> +	struct iio_dev		*indio;
>  	char			phys[32];
>  
>  	struct i2c_client	*client;
> +	struct mutex		mlock;
>  
>  	u16			model;
>  	u16			x_plate_ohms;
> @@ -192,7 +207,10 @@ static irqreturn_t tsc2007_soft_irq(int irq, void *handle)
>  	while (!ts->stopped && tsc2007_is_pen_down(ts)) {
>  
>  		/* pen is down, continue with the measurement */
> +
> +		mutex_lock(&ts->mlock);
>  		tsc2007_read_values(ts, &tc);
> +		mutex_unlock(&ts->mlock);
>  
>  		rt = tsc2007_calculate_resistance(ts, &tc);
>  
> @@ -319,6 +337,86 @@ static void tsc2007_close(struct input_dev *input_dev)
>  	tsc2007_stop(ts);
>  }
>  
> +static const struct iio_chan_spec tsc2007_iio_channel[] = {
> +	TSC2007_CHAN_IIO(0, "x", IIO_VOLTAGE, IIO_CHAN_INFO_RAW),
> +	TSC2007_CHAN_IIO(1, "y", IIO_VOLTAGE, IIO_CHAN_INFO_RAW),
> +	TSC2007_CHAN_IIO(2, "z1", IIO_VOLTAGE, IIO_CHAN_INFO_RAW),
> +	TSC2007_CHAN_IIO(3, "z2", IIO_VOLTAGE, IIO_CHAN_INFO_RAW),
> +	TSC2007_CHAN_IIO(4, "adc", IIO_VOLTAGE, IIO_CHAN_INFO_RAW),
> +	TSC2007_CHAN_IIO(5, "rt", IIO_VOLTAGE, IIO_CHAN_INFO_RAW), /* Ohms? */
This one needs some explanation.  What is it measuring?

> +	TSC2007_CHAN_IIO(6, "pen", IIO_PRESSURE, IIO_CHAN_INFO_RAW),
At the moment this is defined as barometric pressure.  I suppose there
is no reason it can't extend to touch pressure though, even if it's a boolean
like this...

> +	TSC2007_CHAN_IIO(7, "temp0", IIO_TEMP, IIO_CHAN_INFO_RAW),
> +	TSC2007_CHAN_IIO(8, "temp1", IIO_TEMP, IIO_CHAN_INFO_RAW),
I would be tempted to only expose those channels that have a meaning
outside of touch screen usage (e.g. adc, temp0 and temp1).  
> +};
> +
> +static int tsc2007_read_raw(struct iio_dev *indio_dev,
> +	struct iio_chan_spec const *chan, int *val, int *val2, long mask)
> +{
> +	struct  tsc2007 *tsc = iio_priv(indio_dev);
> +	int adc_chan = chan->channel;
> +	int ret = 0;
> +
> +	if (adc_chan >= ARRAY_SIZE(tsc2007_iio_channel))
> +		return -EINVAL;
> +
> +	if (mask != IIO_CHAN_INFO_RAW)
> +		return -EINVAL;
> +
> +	mutex_lock(&tsc->mlock);
> +
> +	switch (chan->channel) {
> +	case 0:
> +		*val = tsc2007_xfer(tsc, READ_X);
> +		break;
> +	case 1:
> +		*val = tsc2007_xfer(tsc, READ_Y);
> +		break;
> +	case 2:
> +		*val = tsc2007_xfer(tsc, READ_Z1);
> +		break;
> +	case 3:
> +		*val = tsc2007_xfer(tsc, READ_Z2);
> +		break;
> +	case 4:
> +		*val = tsc2007_xfer(tsc, (ADC_ON_12BIT | TSC2007_MEASURE_AUX));
> +		break;
> +	case 5: {
> +		struct ts_event tc;
> +
> +		tc.x = tsc2007_xfer(tsc, READ_X);
> +		tc.z1 = tsc2007_xfer(tsc, READ_Z1);
> +		tc.z2 = tsc2007_xfer(tsc, READ_Z2);
> +		*val = tsc2007_calculate_resistance(tsc, &tc);
> +		break;
> +	}
> +	case 6:
> +		*val = tsc2007_is_pen_down(tsc);
> +		break;
> +	case 7:
> +		*val = tsc2007_xfer(tsc,
> +				    (ADC_ON_12BIT | TSC2007_MEASURE_TEMP0));
> +		break;
> +	case 8:
> +		*val = tsc2007_xfer(tsc,
> +				    (ADC_ON_12BIT | TSC2007_MEASURE_TEMP1));
> +		break;
> +	}
> +
> +	/* Prepare for next touch reading - power down ADC, enable PENIRQ */
> +	tsc2007_xfer(tsc, PWRDOWN);
> +
> +	mutex_unlock(&tsc->mlock);
> +
> +	ret = IIO_VAL_INT;
> +
> +	return ret;
> +}
> +
> +static const struct iio_info tsc2007_iio_info = {
> +	.read_raw = tsc2007_read_raw,
> +	.driver_module = THIS_MODULE,
> +};
> +
>  #ifdef CONFIG_OF
>  static int tsc2007_get_pendown_state_gpio(struct device *dev)
>  {
> @@ -453,15 +551,20 @@ static int tsc2007_probe(struct i2c_client *client,
>  	const struct tsc2007_platform_data *pdata = dev_get_platdata(&client->dev);
>  	struct tsc2007 *ts;
>  	struct input_dev *input_dev;
> +	struct iio_dev *indio_dev;
>  	int err;
>  
>  	if (!i2c_check_functionality(client->adapter,
>  				     I2C_FUNC_SMBUS_READ_WORD_DATA))
>  		return -EIO;
>  
> -	ts = devm_kzalloc(&client->dev, sizeof(struct tsc2007), GFP_KERNEL);
> -	if (!ts)
> +	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*ts));
> +	if (!indio_dev) {
> +		dev_err(&client->dev, "iio_device_alloc failed\n");
>  		return -ENOMEM;
> +	}
> +
> +	ts = iio_priv(indio_dev);
>  
>  	input_dev = devm_input_allocate_device(&client->dev);
>  	if (!input_dev)
> @@ -469,10 +572,26 @@ static int tsc2007_probe(struct i2c_client *client,
>  
>  	i2c_set_clientdata(client, ts);
>  
> +	indio_dev->name = "tsc2007";
> +	indio_dev->dev.parent = &client->dev;
> +	indio_dev->info = &tsc2007_iio_info;
> +	indio_dev->modes = INDIO_DIRECT_MODE;
> +	indio_dev->channels = tsc2007_iio_channel;
> +	indio_dev->num_channels = ARRAY_SIZE(tsc2007_iio_channel);
> +
> +	err = iio_device_register(indio_dev);
> +	if (err < 0) {
> +		dev_err(&client->dev, "iio_device_register() failed: %d\n",
> +			err);
> +		return err;
> +	}
> +
>  	ts->client = client;
>  	ts->irq = client->irq;
>  	ts->input = input_dev;
> +	ts->indio = indio_dev;
>  	init_waitqueue_head(&ts->wait);
> +	mutex_init(&ts->mlock);
>  
>  	snprintf(ts->phys, sizeof(ts->phys),
>  		 "%s/input0", dev_name(&client->dev));
> @@ -548,6 +667,19 @@ static int tsc2007_probe(struct i2c_client *client,
>  	return 0;
>  }
>  
> +static int tsc2007_remove(struct i2c_client *client)
> +{
> +	struct tsc2007 *ts = i2c_get_clientdata(client);
> +	struct input_dev *input_dev = ts->input;
> +	struct iio_dev *indio_dev = ts->indio;
> +
> +	input_unregister_device(input_dev);
> +
> +	iio_device_unregister(indio_dev);
> +
> +	return 0;
> +}
> +
>  static const struct i2c_device_id tsc2007_idtable[] = {
>  	{ "tsc2007", 0 },
>  	{ }
> @@ -570,6 +702,7 @@ static struct i2c_driver tsc2007_driver = {
>  	},
>  	.id_table	= tsc2007_idtable,
>  	.probe		= tsc2007_probe,
> +	.remove		= tsc2007_remove,
>  };
>  
>  module_i2c_driver(tsc2007_driver);
> 

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