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

From: Jonathan Cameron
Date: Sat Sep 24 2016 - 12:07:30 EST

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@xxxxxxxxxxxxx>
> ---
> 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);
>