Message-Id: <6A4D5B67-A852-4827-A67D-04A288CDED30@goldelico.com>
Date:   Sun, 23 Oct 2016 21:11:48 +0200
From:   "H. Nikolaus Schaller" <hns@...delico.com>
To:     Jonathan Cameron <jic23@...nel.org>
Cc:     Mark Rutland <mark.rutland@....com>, devicetree@...r.kernel.org,
        linux-omap@...r.kernel.org, Arnd Bergmann <arnd@...db.de>,
        kernel@...a-handheld.com, Tony Lindgren <tony@...mide.com>,
        linux-kernel@...r.kernel.org, Mark Brown <broonie@...nel.org>,
        Dmitry Torokhov <dmitry.torokhov@...il.com>,
        Russell King <linux@...linux.org.uk>,
        linux-iio@...r.kernel.org, Sebastian Reichel <sre@...nel.org>,
        Javier Martinez Canillas <javier@....samsung.com>,
        Rob Herring <robh+dt@...nel.org>,
        Mika Penttilä <mika.penttila@...tfour.com>,
        Benoît Cousson <bcousson@...libre.com>,
        linux-input@...r.kernel.org, Michael Welling <mwelling@...e.org>,
        letux-kernel@...nphoenux.org, "Andrew F. Davis" <afd@...com>,
        Igor Grinberg <grinberg@...pulab.co.il>
Subject: Re: [PATCH v4 4/8] drivers:input:tsc2007: add iio interface to read external ADC input and temperature

Hi,

> Am 23.10.2016 um 21:00 schrieb Jonathan Cameron <jic23@...nel.org>:
> 
> On 23/10/16 19:34, H. Nikolaus Schaller wrote:
>> Hi Jonathan,
>> 
>>> Am 23.10.2016 um 11:57 schrieb H. Nikolaus Schaller <hns@...delico.com>:
>>> 
>>> 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.
>> 
> oops. Didn't look on in my emails to get to this one!
>> 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...
> That's fine.  Stuff that can appear obvious to one person is not
> necessarily obvious to another!
>> 
>>> 
>>>> 
>>>> 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?
> Nope. A local header alongside the driver is what you want for this stuff.
> driver/input/tsc2007.h 

Ah, ok. This makes sense.

>> 
>> 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.
> There will be a few.
>> 
>> And for having proper parameter types I have to make most private structs
>> also public.
> Yes a few of those as well.
>> 
>> 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.
> Usually it is only done once a certain volume of code exists.
>> 
>> So is this intended to give up some static definitions?
> Yes, that happens the moment you have multiple source files.
> 
> Some losses but generally end up with clean code separation. Always a trade
> off unfortunately.  Pity we can't just insist IIO is available! Rather large
> to pull in for what is probable a niche use case.
> 
> Below is definitely heading in the right direction. I remember vaguely being
> convinced of the worth of doing this when optional code is involved!
> (was a good while ago now)

Ok. I think I can now integrate it and then post as PATCH v5 (together with
some other fixes for the patch set).

> 
> Jonathan
>> 
>> 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>
> Should not need this after introducing the new file.  Will only be
> needed in the iio specific .c file.
>> 
>> #define TSC2007_MEASURE_TEMP0          (0x0 << 4)
>> #define TSC2007_MEASURE_AUX            (0x2 << 4)
>> @@ -98,6 +99,9 @@ struct tsc2007 {
> This will definitely need to go in the header though.
>> 
>>        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;
> Spot on.
>> +};
>> +
>> +#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);
> Maybe need a common unwind and use a goto to get to it.

Yes, makes sense.

>>                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);--
>> To unsubscribe from this list: send the line "unsubscribe linux-iio" in
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BR and thanks,
Nikolaus

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