Re: [PATCH v4 4/8] drivers:input:tsc2007: add iio interface to read external ADC input and temperature

[H. Nikolaus Schaller]

Hi Jonathan,

> Am 23.10.2016 um 11:57 schrieb H. Nikolaus Schaller <hns@xxxxxxxxxxxxx>:
> 
> Hi,
> 
>>> +static int tsc2007_alloc(struct i2c_client *client, struct tsc2007 **ts,
>>> +                          struct input_dev **input_dev)
>>> +{
>>> +       int err;
>>> +       struct iio_dev *indio_dev;
>>> +
>>> +       indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*ts));
>> Instead of doing this to reduce the delta between versions make 
>> iio_priv a struct tsc2007 **
>> 
>> That is have a single pointer in there and do your allocation of struct
>> tsc2007 separately.
> 
> Sorry, but I think I do not completely understand what you mean here.
> 
> The problem is that we need to allocate some struct tsc2007 in both cases.
> But in one case managed directly by &client->dev and in the other managed
> indirectly. This is why I use the private area of struct iio_dev to store
> the full struct tsc2007 and not just a pointer.

Ok, I think I finally did understand how you mean this and have started to
implement something.

The idea is to have one alloc function to return a struct tsc2007. This
can be part of the probe function, like it is in the unpatched driver.

In case of iio this struct tsc2007 is also allocated explicitly so that
a pointer can be stored in iio_priv.

This just means an additional iio_priv->ts = devm_kzalloc() in case of iio.

I have added that approach to my inlined patch and it seems to work (attached).

Sorry if I do not use the wording you would use and sometimes overlook
something you have said. I feel here like moving on thin ice and doing
guesswork about unspoken assumptions...

> 
>> 
>> Having doing that, you can have this CONFIG_IIO block as just
>> doing the iio stuff with the input elements pulled back into the main
>> probe function.
>> 
>> Then define something like
>> 
>> iio_configure (stubbed to nothing if no IIO)
>> and
>> iio_unconfigure (also stubbed to nothing if no IIO).

This seems to work (draft attached).

>> 
>> A couple of additions in the header

I think you mean tsc2007.h?

This currently contains only platform data and could IMHO be eliminated
if everything becomes DT.

>> to make it all work
>> (the struct tsc2007 and tsc2007_xfer() + a few of the
>> register defines..

Here it appears to me that I have to make a lot of so far private static
and even static inline functions public so that I can make them stubs and
call them from tsc2007_iio.c.

And for having proper parameter types I have to make most private structs
also public.

I really like the idea to have the optional iio feature in a separate source
file, but when really starting to write code, I get the impression that
it introduces more problems than it solves.

And I wonder a little why it is not done for #ifdef CONFIG_OF in tsc2007.c
as well. There are also two static function in some #ifdef #else # endif
and not going through stubs.

So is this intended to give up some static definitions?

BR and thanks,
Nikolaus

diff --git a/drivers/input/touchscreen/tsc2007.c b/drivers/input/touchscreen/tsc2007.c
index 5e3c4bf..92da8f6 100644
--- a/drivers/input/touchscreen/tsc2007.c
+++ b/drivers/input/touchscreen/tsc2007.c
@@ -30,6 +30,7 @@
 #include <linux/of.h>
 #include <linux/of_gpio.h>
 #include <linux/input/touchscreen.h>
+#include <linux/iio/iio.h>
 
 #define TSC2007_MEASURE_TEMP0          (0x0 << 4)
 #define TSC2007_MEASURE_AUX            (0x2 << 4)
@@ -98,6 +99,9 @@ struct tsc2007 {
 
        int                     (*get_pendown_state)(struct device *);
        void                    (*clear_penirq)(void);
+
+       struct mutex            mlock;
+       void                    *private;
 };
 
 static inline int tsc2007_xfer(struct tsc2007 *tsc, u8 cmd)
@@ -192,7 +196,10 @@ 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 +326,157 @@ static void tsc2007_close(struct input_dev *input_dev)
        tsc2007_stop(ts);
 }
 
+#ifdef CONFIG_IIO
+
+struct tsc2007_iio {
+       struct tsc2007 *ts;
+};
+
+#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, \
+}
+
+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? */
+       TSC2007_CHAN_IIO(6, "pen", IIO_PRESSURE, IIO_CHAN_INFO_RAW),
+       TSC2007_CHAN_IIO(7, "temp0", IIO_TEMP, IIO_CHAN_INFO_RAW),
+       TSC2007_CHAN_IIO(8, "temp1", IIO_TEMP, IIO_CHAN_INFO_RAW),
+};
+
+static int tsc2007_read_raw(struct iio_dev *indio_dev,
+       struct iio_chan_spec const *chan, int *val, int *val2, long mask)
+{
+       struct tsc2007_iio *iio = iio_priv(indio_dev);
+       struct tsc2007 *tsc = iio->ts;
+       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,
+};
+
+static inline int tsc2007_iio_configure(struct tsc2007 *ts)
+{
+       int err;
+       struct iio_dev *indio_dev;
+       struct tsc2007_iio *iio;
+
+       indio_dev = devm_iio_device_alloc(&ts->client->dev, sizeof(struct tsc2007_iio));
+       if (!indio_dev) {
+               dev_err(&ts->client->dev, "iio_device_alloc failed\n");
+               return -ENOMEM;
+       }
+
+       iio = iio_priv(indio_dev);
+       iio->ts = ts;
+       ts->private = (void *) indio_dev;
+
+       indio_dev->name = "tsc2007";
+       indio_dev->dev.parent = &ts->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(&ts->client->dev, "iio_device_register() failed: %d\n",
+                       err);
+               return err;
+       }
+
+       return 0;
+}
+
+static inline void tsc2007_iio_unconfigure(struct tsc2007 *ts)
+{
+       struct iio_dev *indio_dev = ts->private;
+
+       iio_device_unregister(indio_dev);
+}
+
+#else /* CONFIG_IIO */
+
+static inline int tsc2007_iio_configure(struct tsc2007 *ts)
+{
+       /* not needed */
+}
+
+static inline void tsc2007_iio_unconfigure(struct tsc2007 *ts)
+{
+       /* not needed */
+}
+
+#endif /* CONFIG_IIO */
+
 #ifdef CONFIG_OF
 static int tsc2007_get_pendown_state_gpio(struct device *dev)
 {
@@ -472,7 +630,13 @@ static int tsc2007_probe(struct i2c_client *client,
        ts->client = client;
        ts->irq = client->irq;
        ts->input = input_dev;
+
+       err = tsc2007_iio_configure(ts);
+       if (err < 0)
+               return err;
+
        init_waitqueue_head(&ts->wait);
+       mutex_init(&ts->mlock);
 
        snprintf(ts->phys, sizeof(ts->phys),
                 "%s/input0", dev_name(&client->dev));
@@ -503,8 +667,10 @@ static int tsc2007_probe(struct i2c_client *client,
                                                          ts->fuzzz, 0);
        } else {
                err = tsc2007_probe_dt(client, ts);
-               if (err)
+               if (err) {
+                       tsc2007_iio_unconfigure(ts);
                        return err;
+               }
        }
 
        if (pdata) {
@@ -516,6 +682,7 @@ static int tsc2007_probe(struct i2c_client *client,
                                dev_err(&client->dev,
                                        "Failed to register exit_platform_hw action, %d\n",
                                        err);
+                               tsc2007_iio_unconfigure(ts);
                                return err;
                        }
                }
@@ -533,6 +700,7 @@ static int tsc2007_probe(struct i2c_client *client,
        if (err) {
                dev_err(&client->dev, "Failed to request irq %d: %d\n",
                        ts->irq, err);
+               tsc2007_iio_unconfigure(ts);
                return err;
        }
 
@@ -543,6 +711,7 @@ static int tsc2007_probe(struct i2c_client *client,
        if (err < 0) {
                dev_err(&client->dev,
                        "Failed to setup chip: %d\n", err);
+               tsc2007_iio_unconfigure(ts);
                return err;     /* usually, chip does not respond */
        }
 
@@ -550,12 +719,21 @@ static int tsc2007_probe(struct i2c_client *client,
        if (err) {
                dev_err(&client->dev,
                        "Failed to register input device: %d\n", err);
+               tsc2007_iio_unconfigure(ts);
                return err;
        }
 
        return 0;
 }
 
+static int tsc2007_remove(struct i2c_client *client)
+{
+       struct tsc2007 *ts = i2c_get_clientdata(client);
+       tsc2007_iio_unconfigure(ts);
+       input_unregister_device(ts->input);
+       return 0;
+}
+
 static const struct i2c_device_id tsc2007_idtable[] = {
        { "tsc2007", 0 },
        { }
@@ -578,6 +756,7 @@ static struct i2c_driver tsc2007_driver = {
        },
        .id_table       = tsc2007_idtable,
        .probe          = tsc2007_probe,
+       .remove         = tsc2007_remove,
 };
 
 module_i2c_driver(tsc2007_driver);