Hi Dimtry,

Thanks for the feedback. I will prepare a v3 of the patch with the things you 
pointed out fixed and a more meaningful description and changelog.
I have a few  questions regarding your comments (see below).

>Hi Patrick,
>
>On Tue, Feb 21, 2017 at 07:40:20AM +0100, Patrick Vogelaar wrote:
>> Version 2:
>> * removed .owner
>> * based on branch next
>
>A better changelog would be nice: the kid of device, limitations, etc.
>
>>
>> Signed-off-by: Patrick Vogelaar <patrick.vogel...@gigatronik.com>
>> ---
>>  drivers/input/misc/Kconfig       |  12 +++
>>  drivers/input/misc/Makefile      |   1 +
>>  drivers/input/misc/cy8cmbr3102.c | 221
>> +++++++++++++++++++++++++++++++++++++++
>>  3 files changed, 234 insertions(+)
>>  create mode 100644 drivers/input/misc/cy8cmbr3102.c
>>
>> diff --git a/drivers/input/misc/Kconfig b/drivers/input/misc/Kconfig
>> index 5b6c522..be3071e 100644
>> --- a/drivers/input/misc/Kconfig
>> +++ b/drivers/input/misc/Kconfig
>> @@ -822,4 +822,16 @@ config INPUT_HISI_POWERKEY
>>        To compile this driver as a module, choose M here: the
>>        module will be called hisi_powerkey.
>>
>> +config INPUT_CY8CMBR3102
>> +    tristate "Cypress CY8CMBR3102 CapSense Express controller"
>> +    depends on I2C
>> +    select INPUT_POLLDEV
>> +    default n
>
>"default n" can be omitted.
>
>> +    help
>> +      Say yes here to enable support for the Cypress CY8CMBR3102
>> +      CapSense Express controller.
>> +
>> +      To compile this driver as a module, choose M here: the module
>> +      will be called cy8cmbr3102.
>> +
>>  endif
>> diff --git a/drivers/input/misc/Makefile b/drivers/input/misc/Makefile
>> index b10523f..f9959ed 100644
>> --- a/drivers/input/misc/Makefile
>> +++ b/drivers/input/misc/Makefile
>> @@ -77,3 +77,4 @@ obj-$(CONFIG_INPUT_WM831X_ON)              +=
>wm831x-on.o
>>  obj-$(CONFIG_INPUT_XEN_KBDDEV_FRONTEND)     += xen-kbdfront.o
>>  obj-$(CONFIG_INPUT_YEALINK)         += yealink.o
>>  obj-$(CONFIG_INPUT_IDEAPAD_SLIDEBAR)        += ideapad_slidebar.o
>> +obj-$(CONFIG_INPUT_CY8CMBR3102)             += cy8cmbr3102.o
>> diff --git a/drivers/input/misc/cy8cmbr3102.c
>> b/drivers/input/misc/cy8cmbr3102.c
>> new file mode 100644
>> index 0000000..ed67a63
>> --- /dev/null
>> +++ b/drivers/input/misc/cy8cmbr3102.c
>> @@ -0,0 +1,221 @@
>> +/* Driver for Cypress CY8CMBR3102 CapSense Express Controller
>> + *
>> + * (C) 2017 by Gigatronik Technologies GmbH
>> + * Author: Patrick Vogelaar <patrick.vogel...@gigatronik.com>
>> + * All rights reserved.
>> + *
>> + * This code is based on mma8450.c and atmel_captouch.c.
>> + *
>> + * This program is free software; you can redistribute it and/or
>> +modify
>> + * it under the terms of the GNU General Public License as published
>> +by
>> + * the Free Software Foundation; version 2 of the License.
>> + *
>> + * This program is distributed in the hope that it will be useful,
>> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
>> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
>> + * GNU General Public License for more details.
>> + *
>> + * NOTE: This implementation does not implement the full range of
>> +functions the
>> + * Cypress CY8CMBR3102 CapSense Express controller provides. It only
>> +implements
>> + * its use for connected touch buttons (yet).
>> + */
>> +
>> +#define DRV_VERSION "0.1"
>> +
>> +#include <linux/kernel.h>
>> +#include <linux/module.h>
>> +#include <linux/device.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/i2c.h>
>> +#include <linux/input.h>
>> +#include <linux/input-polldev.h>
>> +#include <linux/of.h>
>> +
>> +/* I2C Registers */
>> +#define CY8CMBR3102_DEVICE_ID_REG           0x90
>> +#define CY8CMBR3102_BUTTON_STAT                     0xAA
>> +
>> +
>> +#define CY8CMBR3102_MAX_NUM_OF_BUTTONS              0x02
>> +#define CY8CMBR3102_DRV_NAME                        "cy8cmbr3102"
>> +#define CY8CMBR3102_POLL_INTERVAL           200
>> +#define CY8CMBR3102_POLL_INTERVAL_MAX               300
>> +#define CY8CMBR3102_DEVICE_ID                       2561
>> +#define CY8CMBR3102_MAX_RETRY                       5
>> +
>> +/*
>> + * @i2c_client: I2C slave device client pointer
>> + * @idev: Input (polled) device pointer
>
>This kind of comments are not really helpful and just clutter the source.
>Anyone looking at the structure can see that they are dealing with i2c client
>pointer and polled input device pointer.
>
>> + * @num_btn: Number of buttons
>> + * @keycodes: map of button# to KeyCode
>> + * @cy8cmbr3102_lock: mutex lock
>> + */
>> +struct cy8cmbr3102_device {
>> +    struct i2c_client *client;
>> +    struct input_polled_dev *idev;
>> +    u32 num_btn;
>> +    u32 keycodes[CY8CMBR3102_MAX_NUM_OF_BUTTONS];
>> +    struct mutex cy8cmbr3102_lock;
>
>I do not think you need this mutex: we will not run several instances of poll
>function simultaneously.
>
>> +};
>> +
>> +static const struct i2c_device_id cy8cmbr3102_idtable[] = {
>> +            {"cy8cmbr3102", 0},
>> +            {}
>
>Extra indent.
>
>> +};
>> +MODULE_DEVICE_TABLE(i2c, cy8cmbr3102_idtable);
>
>Please move to the driver structure.
>
>> +
>> +static void cy8cmbr3102_poll(struct input_polled_dev *idev) {
>> +    struct cy8cmbr3102_device *dev = idev->private;
>> +    int i, ret, btn_state;
>> +
>> +    mutex_lock(&dev->cy8cmbr3102_lock);
>> +
>> +    ret = i2c_smbus_read_word_data(dev->client,
>CY8CMBR3102_BUTTON_STAT);
>> +    if (ret < 0) {
>> +            dev_err(&dev->client->dev, "i2c io error: %d\n", ret);
>> +            mutex_unlock(&dev->cy8cmbr3102_lock);
>> +            return;
>> +    }
>> +
>> +    for (i = 0; i < dev->num_btn; i++) {
>> +            btn_state = ret & (0x1 << i);
>> +            input_report_key(idev->input, dev->keycodes[i], btn_state);
>
>               input_report_key(idev->input, dev->keycodes[i], ret & BIT(i));
>
>> +            input_sync(idev->input);
>> +    }
>> +
>> +    mutex_unlock(&dev->cy8cmbr3102_lock);
>> +}
>> +
>> +static int cy8cmbr3102_remove(struct i2c_client *client) {
>> +    struct cy8cmbr3102_device *dev = i2c_get_clientdata(client);
>> +    struct input_polled_dev *idev = dev->idev;
>> +
>> +    dev_dbg(&client->dev, "%s\n", __func__);
>> +
>> +    mutex_destroy(&dev->cy8cmbr3102_lock);
>> +    input_unregister_polled_device(idev);
>
>Not needed with devm. In fact, this whole function is not needed.
>> +
>> +    return 0;
>> +}
>> +
>> +static int cy8cmbr3102_probe(struct i2c_client *client,
>> +                            const struct i2c_device_id *id)
>> +{
>> +    struct cy8cmbr3102_device *drvdata;
>> +    struct device *dev = &client->dev;
>> +    struct device_node *node;
>> +    int i, err, ret;
>> +
>> +    dev_dbg(&client->dev, "%s\n", __func__);
>> +
>> +    if (!i2c_check_functionality(client->adapter,
>I2C_FUNC_SMBUS_BYTE_DATA |
>> +
>       I2C_FUNC_SMBUS_WORD_DATA |
>> +
>       I2C_FUNC_SMBUS_I2C_BLOCK)) {
>> +            dev_err(dev, "needed i2c functionality is not supported\n");
>> +            return -EINVAL;
>> +    }
>> +
>> +    drvdata = devm_kzalloc(dev, sizeof(*drvdata), GFP_KERNEL);
>> +    if (!drvdata)
>> +            return -ENOMEM;
>> +
>> +    drvdata->client = client;
>> +    i2c_set_clientdata(client, drvdata);
>> +
>> +    /* device is in low-power mode and needs to be waken up */
>> +    for (i = 0; (i < CY8CMBR3102_MAX_RETRY) &&
>> +                                    (ret != CY8CMBR3102_DEVICE_ID); i++)
>{
>> +            ret = i2c_smbus_read_word_data(drvdata->client,
>> +            CY8CMBR3102_DEVICE_ID_REG);
>
>Weird indent.
>
>> +            dev_dbg(dev, "DEVICE_ID (%i): %i\n", i, ret);
>> +    }
>> +
>> +    if (ret < 0) {
>> +            dev_err(&client->dev, "i2c io error: %d\n", ret);
>> +            return -EIO;
>
>               return ret;
>
>> +    } else if (ret != CY8CMBR3102_DEVICE_ID) {
>> +            dev_err(&client->dev, "read device ID %i is not equal to
>%i!\n",
>> +                            ret, CY8CMBR3102_DEVICE_ID);
>> +            return -ENXIO;
>> +    }
>> +    dev_dbg(dev, "device identified by device ID\n");
>> +
>> +    drvdata->idev = devm_input_allocate_polled_device(dev);
>> +    if (!drvdata->idev) {
>> +            dev_err(dev, "failed to allocate input device\n");
>> +            return -ENOMEM;
>> +    }
>> +

Is it still necessary to check if a of_node is  available if I use the generic 
device properties.  I tried to find a more generic way for this but couldn't 
find anything

>> +    node = dev->of_node;
>> +    if (!node) {
>> +            dev_err(dev, "failed to find matching node in device tree\n");
>> +            return -EINVAL;
>> +    }
>
>Please drop.
>
>> +
>> +    if (of_property_read_bool(node, "autorepeat"))
>
>Use generic device properties:
>
>       if (device_property_read_bool(...))
>
>> +            __set_bit(EV_REP, drvdata->idev->input->evbit);
>> +
>> +    drvdata->num_btn = of_property_count_u32_elems(node,
>> +"linux,keycodes");
>
>       size = device_property_read_u32_array(dev, "linux,keycodes", NULL,
>0);
>       ... etc.
>
>Se matrix-keymap.c for parsing.
>
>
>> +    if (drvdata->num_btn > CY8CMBR3102_MAX_NUM_OF_BUTTONS)
>> +            drvdata->num_btn =
>CY8CMBR3102_MAX_NUM_OF_BUTTONS;
>> +
>> +    err = of_property_read_u32_array(node, "linux,keycodes",
>> +                    drvdata->keycodes, drvdata->num_btn);
>> +
>> +    if (err) {
>> +            dev_err(dev, "failed to read linux,keycodes property: %d\n",
>> +                            err);
>> +            return err;
>> +    }
>> +
>> +    for (i = 0; i < drvdata->num_btn; i++)
>> +            __set_bit(drvdata->keycodes[i], drvdata->idev->input-
>>keybit);
>> +
>> +    drvdata->idev->input->id.bustype = BUS_I2C;
>> +    drvdata->idev->input->id.product = 0x3102;
>> +    drvdata->idev->input->id.version = 0;
>> +    drvdata->idev->input->name = CY8CMBR3102_DRV_NAME;
>> +    drvdata->idev->poll = cy8cmbr3102_poll;
>> +    drvdata->idev->poll_interval = CY8CMBR3102_POLL_INTERVAL;
>> +    drvdata->idev->poll_interval_max =
>CY8CMBR3102_POLL_INTERVAL_MAX;
>> +    drvdata->idev->private = drvdata;
>> +    drvdata->idev->input->keycode = drvdata->keycodes;
>> +    drvdata->idev->input->keycodemax = drvdata->num_btn;
>> +    drvdata->idev->input->keycodesize = sizeof(drvdata->keycodes[0]);
>> +    __set_bit(EV_KEY, drvdata->idev->input->evbit);
>> +
>> +    mutex_init(&drvdata->cy8cmbr3102_lock);
>> +
>> +    err = input_register_polled_device(drvdata->idev);
>> +    if (err)
>> +            return err;
>> +
>> +    dev_info(&client->dev, "chip found, driver version " DRV_VERSION
>> +"\n");
>

What exactly should I drop here? The return 0? If so, could you please explain 
to me why. Thanks

>Please drop.
>
>> +    return 0;
>> +}
>> +
>> +#ifdef CONFIG_OF
>> +static const struct of_device_id of_cy8cmbr3102_match[] = {
>> +            {.compatible = "cypress,cy8cmbr3102", },
>> +            {}
>> +};
>> +MODULE_DEVICE_TABLE(of, of_cy8cmbr3102_match); #endif
>> +
>> +static struct i2c_driver cy8cmbr3102_driver = {
>> +            .driver                 = {
>> +                    .name           = "cy8cmbr3102",
>> +                    .of_match_table =
>of_match_ptr(of_cy8cmbr3102_match),
>> +            },
>> +            .probe = cy8cmbr3102_probe,
>> +            .remove = cy8cmbr3102_remove,
>> +            .id_table = cy8cmbr3102_idtable,
>> +};
>> +module_i2c_driver(cy8cmbr3102_driver);
>> +
>> +MODULE_AUTHOR("Patrick Vogelaar
><patrick.vogel...@gigatronik.com>");
>> +MODULE_DESCRIPTION("Cypress CY8CMBR3102 CapSense Express
>> +controller"); MODULE_LICENSE("GPL");
>MODULE_VERSION(DRV_VERSION);
>> --
>> 2.7.4
>>
>
>Thanks.
>
>--
>Dmitry

Thanks

Patrick

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