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

H. Nikolaus Schaller hns at goldelico.com
Sat Oct 22 22:46:21 CEST 2016


Hi Jonathan,

> Am 22.10.2016 um 20:33 schrieb Jonathan Cameron <jic23 at kernel.org>:
> 
> On 17/10/16 14:57, 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.
>> 
>> Since it is not wasting much resources and is very straightforward,
>> we simply provide all other adc channels as optional iio interfaces
>> as weel. This can be used for debugging or special applications.
> well
>> 
>> Signed-off-by: H. Nikolaus Schaller <hns at goldelico.com>
> This could be cleaner done perhaps by factoring out the IIO stuff into a separate
> file and using a header with stubs to deal with the no available case.
> 
> There will only be a handful of stubs and it'll give you a lot cleaner code
> in here.
> 
> If def fun in .c files is always harder to deal with than in a header
> where stubs are really obvious.

Yes, it became a lot of #ifdefs spread over the source file.

The easiest thing would be to require IIO to be enabled :)

With your proposal to consider refactoring, I think the crucial part
is the conditional allocation either through devm_iio_device_alloc()
or devm_kzalloc(). This can be refactored into some conditional
tsc2007_alloc().

I have tried some draft (not tested and not tidied up) to check if the
direction is good.

This reduces the number of #ifdef CONFIG_IIO from 7 to 2 without introducing
new files or includes. There are also 2 other #ifdef CONFIG_OF so it doesn't
seem to be very complex now in comparison. And the patch itself has only a
handful of hunks (8).

Moving tsc2007_alloc into a separate file tsc2007_iio.c would only move around
one #ifdef CONFIG_OF from tsc2007.c but IMHO makes it more difficult to understand
because it is not really iio specific and one has to switch between two source
files. And I would have to touch the Makefile as well.

What do you think?

If generally ok, I can include that in [PATCH v5].

BR and thanks,
Nikolaus


diff --git a/drivers/input/touchscreen/tsc2007.c b/drivers/input/touchscreen/tsc2007.c
index 5e3c4bf..691e79f 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)
@@ -69,9 +70,13 @@ struct ts_event {
 
 struct tsc2007 {
        struct input_dev        *input;
+#ifdef CONFIG_IIO
+       struct iio_dev          *indio;
+#endif
        char                    phys[32];
 
        struct i2c_client       *client;
+       struct mutex            mlock;
 
        u16                     model;
        u16                     x_plate_ohms;
@@ -192,7 +197,10 @@ 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 +327,162 @@ static void tsc2007_close(struct input_dev *input_dev)
        tsc2007_stop(ts);
 }
 
+#ifdef CONFIG_IIO
+
+#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 *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,
+};
+
+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));
+       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)
+               return -ENOMEM;
+
+       i2c_set_clientdata(client, *ts);
+       (*ts)->indio = indio_dev;
+
+       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;
+       }
+
+       return 0;
+}
+
+#define tsc2007_iio_device_unregister(ts) iio_device_unregister(ts->indio)
+
+#else /* CONFIG_IIO */
+
+static int tsc2007_alloc(struct i2c_client *client, struct tsc2007 **ts,
+                          struct input_dev **input_dev)
+{
+       int err;
+
+       *ts = devm_kzalloc(&client->dev, sizeof(struct tsc2007), GFP_KERNEL);
+       if (!*ts)
+               return -ENOMEM;
+
+       *input_dev = devm_input_allocate_device(&client->dev);
+       if (!*input_dev)
+               return -ENOMEM;
+
+       i2c_set_clientdata(client, *ts);
+
+       return 0;
+}
+
+#define tsc2007_iio_device_unregister(ts) /* not needed */
+
+#endif /* CONFIG_IIO */
+
 #ifdef CONFIG_OF
 static int tsc2007_get_pendown_state_gpio(struct device *dev)
 {
@@ -459,20 +623,15 @@ static int tsc2007_probe(struct i2c_client *client,
                                     I2C_FUNC_SMBUS_READ_WORD_DATA))
                return -EIO;
 
-       ts = devm_kzalloc(&client->dev, sizeof(struct tsc2007), GFP_KERNEL);
-       if (!ts)
-               return -ENOMEM;
-
-       input_dev = devm_input_allocate_device(&client->dev);
-       if (!input_dev)
-               return -ENOMEM;
-
-       i2c_set_clientdata(client, ts);
+       err = tsc2007_alloc(client, &ts, &input_dev);
+       if (err < 0)
+               return err;
 
        ts->client = client;
        ts->irq = client->irq;
        ts->input = input_dev;
        init_waitqueue_head(&ts->wait);
+       mutex_init(&ts->mlock);
 
        snprintf(ts->phys, sizeof(ts->phys),
                 "%s/input0", dev_name(&client->dev));
@@ -543,6 +702,7 @@ static int tsc2007_probe(struct i2c_client *client,
        if (err < 0) {
                dev_err(&client->dev,
                        "Failed to setup chip: %d\n", err);
+               tsc2007_iio_device_unregister(ts);
                return err;     /* usually, chip does not respond */
        }
 
@@ -556,6 +716,14 @@ 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);
+       input_unregister_device(ts->input);
+       tsc2007_iio_device_unregister(ts);
+       return 0;
+}
+
 static const struct i2c_device_id tsc2007_idtable[] = {
        { "tsc2007", 0 },
        { }
@@ -578,6 +746,7 @@ 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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