Date:   Sun, 29 Mar 2020 10:48:11 +0100
From:   Jonathan Cameron <jic23@...nel.org>
To:     Artur Rojek <contact@...ur-rojek.eu>
Cc:     Dmitry Torokhov <dmitry.torokhov@...il.com>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Paul Cercueil <paul@...pouillou.net>,
        Heiko Stuebner <heiko@...ech.de>, linux-input@...r.kernel.org,
        devicetree@...r.kernel.org, linux-iio@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 5/5] input: joystick: Add ADC attached joystick
 driver.

On Tue, 24 Mar 2020 12:23:36 +0100
Artur Rojek <contact@...ur-rojek.eu> wrote:

> Add a driver for joystick devices connected to ADC controllers
> supporting the Industrial I/O subsystem.
> 
> Signed-off-by: Artur Rojek <contact@...ur-rojek.eu>
> Tested-by: Paul Cercueil <paul@...pouillou.net>
> Tested-by: Heiko Stuebner <heiko@...ech.de>
> Acked-by: Dmitry Torokhov <dmitry.torokhov@...il.com>

Whole series looks good to me. So now or the question of how to take
it (if I've forgotten us already having this conversation please remind
me!)

From an IIO point of view we've missed the coming merge window.

I 'think' patches
* 1-3 are IIO only and
* 4-5 input only.

It should be fine to either take them separately through the relevant
trees.   Dmitry, would you prefer that or shall I do an immutable
branch based on rc1 in a few weeks time?

Jonathan

> ---
> 
>  v2: - sanity check supported channel format on probe,
>      - rename adc_joystick_disable to a more sensible adc_joystick_cleanup, 
>      - enforce correct axis order by checking the `reg` property of
>        child nodes
> 
>  v3-v5: no change
> 
>  drivers/input/joystick/Kconfig        |  10 ++
>  drivers/input/joystick/Makefile       |   1 +
>  drivers/input/joystick/adc-joystick.c | 245 ++++++++++++++++++++++++++
>  3 files changed, 256 insertions(+)
>  create mode 100644 drivers/input/joystick/adc-joystick.c
> 
> diff --git a/drivers/input/joystick/Kconfig b/drivers/input/joystick/Kconfig
> index 940b744639c7..efbc20ec5099 100644
> --- a/drivers/input/joystick/Kconfig
> +++ b/drivers/input/joystick/Kconfig
> @@ -42,6 +42,16 @@ config JOYSTICK_A3D
>  	  To compile this driver as a module, choose M here: the
>  	  module will be called a3d.
>  
> +config JOYSTICK_ADC
> +	tristate "Simple joystick connected over ADC"
> +	depends on IIO
> +	select IIO_BUFFER_CB
> +	help
> +	  Say Y here if you have a simple joystick connected over ADC.
> +
> +	  To compile this driver as a module, choose M here: the
> +	  module will be called adc-joystick.
> +
>  config JOYSTICK_ADI
>  	tristate "Logitech ADI digital joysticks and gamepads"
>  	select GAMEPORT
> diff --git a/drivers/input/joystick/Makefile b/drivers/input/joystick/Makefile
> index 8656023f6ef5..58232b3057d3 100644
> --- a/drivers/input/joystick/Makefile
> +++ b/drivers/input/joystick/Makefile
> @@ -6,6 +6,7 @@
>  # Each configuration option enables a list of files.
>  
>  obj-$(CONFIG_JOYSTICK_A3D)		+= a3d.o
> +obj-$(CONFIG_JOYSTICK_ADC)		+= adc-joystick.o
>  obj-$(CONFIG_JOYSTICK_ADI)		+= adi.o
>  obj-$(CONFIG_JOYSTICK_AMIGA)		+= amijoy.o
>  obj-$(CONFIG_JOYSTICK_AS5011)		+= as5011.o
> diff --git a/drivers/input/joystick/adc-joystick.c b/drivers/input/joystick/adc-joystick.c
> new file mode 100644
> index 000000000000..9cb9896da26e
> --- /dev/null
> +++ b/drivers/input/joystick/adc-joystick.c
> @@ -0,0 +1,245 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Input driver for joysticks connected over ADC.
> + * Copyright (c) 2019-2020 Artur Rojek <contact@...ur-rojek.eu>
> + */
> +#include <linux/ctype.h>
> +#include <linux/input.h>
> +#include <linux/iio/iio.h>
> +#include <linux/iio/consumer.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/platform_device.h>
> +#include <linux/property.h>
> +
> +struct adc_joystick_axis {
> +	u32 code;
> +	s32 range[2];
> +	s32 fuzz;
> +	s32 flat;
> +};
> +
> +struct adc_joystick {
> +	struct input_dev *input;
> +	struct iio_cb_buffer *buffer;
> +	struct adc_joystick_axis *axes;
> +	struct iio_channel *chans;
> +	int num_chans;
> +};
> +
> +static int adc_joystick_handle(const void *data, void *private)
> +{
> +	struct adc_joystick *joy = private;
> +	enum iio_endian endianness;
> +	int bytes, msb, val, i;
> +	bool sign;
> +
> +	bytes = joy->chans[0].channel->scan_type.storagebits >> 3;
> +
> +	for (i = 0; i < joy->num_chans; ++i) {
> +		endianness = joy->chans[i].channel->scan_type.endianness;
> +		msb = joy->chans[i].channel->scan_type.realbits - 1;
> +		sign = (tolower(joy->chans[i].channel->scan_type.sign) == 's');
> +
> +		switch (bytes) {
> +		case 1:
> +			val = ((const u8 *)data)[i];
> +			break;
> +		case 2:
> +			val = ((const u16 *)data)[i];
> +			if (endianness == IIO_BE)
> +				val = be16_to_cpu(val);
> +			else if (endianness == IIO_LE)
> +				val = le16_to_cpu(val);
> +			break;
> +		default:
> +			return -EINVAL;
> +		}
> +
> +		val >>= joy->chans[i].channel->scan_type.shift;
> +		if (sign)
> +			val = sign_extend32(val, msb);
> +		else
> +			val &= GENMASK(msb, 0);
> +		input_report_abs(joy->input, joy->axes[i].code, val);
> +	}
> +
> +	input_sync(joy->input);
> +
> +	return 0;
> +}
> +
> +static int adc_joystick_open(struct input_dev *dev)
> +{
> +	struct adc_joystick *joy = input_get_drvdata(dev);
> +	int ret;
> +
> +	ret = iio_channel_start_all_cb(joy->buffer);
> +	if (ret)
> +		dev_err(dev->dev.parent, "Unable to start callback buffer");
> +
> +	return ret;
> +}
> +
> +static void adc_joystick_close(struct input_dev *dev)
> +{
> +	struct adc_joystick *joy = input_get_drvdata(dev);
> +
> +	iio_channel_stop_all_cb(joy->buffer);
> +}
> +
> +static void adc_joystick_cleanup(void *data)
> +{
> +	iio_channel_release_all_cb(data);
> +}
> +
> +static int adc_joystick_set_axes(struct device *dev, struct adc_joystick *joy)
> +{
> +	struct adc_joystick_axis *axes;
> +	struct fwnode_handle *child;
> +	int num_axes, ret, i;
> +
> +	num_axes = device_get_child_node_count(dev);
> +	if (!num_axes) {
> +		dev_err(dev, "Unable to find child nodes");
> +		return -EINVAL;
> +	}
> +
> +	if (num_axes != joy->num_chans) {
> +		dev_err(dev, "Got %d child nodes for %d channels",
> +			num_axes, joy->num_chans);
> +		return -EINVAL;
> +	}
> +
> +	axes = devm_kmalloc_array(dev, num_axes, sizeof(*axes), GFP_KERNEL);
> +	if (!axes)
> +		return -ENOMEM;
> +
> +	device_for_each_child_node(dev, child) {
> +		ret = fwnode_property_read_u32(child, "reg", &i);
> +		if (ret || i >= num_axes) {
> +			dev_err(dev, "reg invalid or missing");
> +			goto err;
> +		}
> +
> +		if (fwnode_property_read_u32(child, "linux,code",
> +					     &axes[i].code)) {
> +			dev_err(dev, "linux,code invalid or missing");
> +			goto err;
> +		}
> +
> +		if (fwnode_property_read_u32_array(child, "abs-range",
> +						   axes[i].range, 2)) {
> +			dev_err(dev, "abs-range invalid or missing");
> +			goto err;
> +		}
> +
> +		fwnode_property_read_u32(child, "abs-fuzz",
> +					 &axes[i].fuzz);
> +		fwnode_property_read_u32(child, "abs-flat",
> +					 &axes[i].flat);
> +
> +		input_set_abs_params(joy->input, axes[i].code,
> +				     axes[i].range[0], axes[i].range[1],
> +				     axes[i].fuzz,
> +				     axes[i].flat);
> +		input_set_capability(joy->input, EV_ABS, axes[i].code);
> +	}
> +
> +	joy->axes = axes;
> +
> +	return 0;
> +
> +err:
> +	fwnode_handle_put(child);
> +	return -EINVAL;
> +}
> +
> +static int adc_joystick_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct adc_joystick *joy;
> +	struct input_dev *input;
> +	int bits, ret, i;
> +
> +	joy = devm_kzalloc(dev, sizeof(*joy), GFP_KERNEL);
> +	if (!joy)
> +		return -ENOMEM;
> +
> +	joy->chans = devm_iio_channel_get_all(dev);
> +	if (IS_ERR(joy->chans)) {
> +		ret = PTR_ERR(joy->chans);
> +		if (ret != -EPROBE_DEFER)
> +			dev_err(dev, "Unable to get IIO channels");
> +		return ret;
> +	}
> +
> +	/* Count how many channels we got. NULL terminated. */
> +	while (joy->chans[joy->num_chans].indio_dev)
> +		joy->num_chans++;
> +
> +	bits = joy->chans[0].channel->scan_type.storagebits;
> +	if (!bits || (bits >> 3) > 2) {
> +		dev_err(dev, "Unsupported channel storage size");
> +		return -EINVAL;
> +	}
> +	for (i = 1; i < joy->num_chans; ++i)
> +		if (joy->chans[i].channel->scan_type.storagebits != bits) {
> +			dev_err(dev, "Channels must have equal storage size");
> +			return -EINVAL;
> +		}
> +
> +	input = devm_input_allocate_device(dev);
> +	if (!input) {
> +		dev_err(dev, "Unable to allocate input device");
> +		return -ENOMEM;
> +	}
> +
> +	joy->input = input;
> +	input->name = pdev->name;
> +	input->id.bustype = BUS_HOST;
> +	input->open = adc_joystick_open;
> +	input->close = adc_joystick_close;
> +
> +	ret = adc_joystick_set_axes(dev, joy);
> +	if (ret)
> +		return ret;
> +
> +	input_set_drvdata(input, joy);
> +	ret = input_register_device(input);
> +	if (ret) {
> +		dev_err(dev, "Unable to register input device: %d", ret);
> +		return ret;
> +	}
> +
> +	joy->buffer = iio_channel_get_all_cb(dev, adc_joystick_handle, joy);
> +	if (IS_ERR(joy->buffer)) {
> +		dev_err(dev, "Unable to allocate callback buffer");
> +		return PTR_ERR(joy->buffer);
> +	}
> +
> +	ret = devm_add_action_or_reset(dev, adc_joystick_cleanup, joy->buffer);
> +	if (ret)
> +		dev_err(dev, "Unable to add action");
> +
> +	return ret;
> +}
> +
> +static const struct of_device_id adc_joystick_of_match[] = {
> +	{ .compatible = "adc-joystick", },
> +	{ },
> +};
> +MODULE_DEVICE_TABLE(of, adc_joystick_of_match);
> +
> +static struct platform_driver adc_joystick_driver = {
> +	.driver = {
> +		.name = "adc-joystick",
> +		.of_match_table = of_match_ptr(adc_joystick_of_match),
> +	},
> +	.probe = adc_joystick_probe,
> +};
> +module_platform_driver(adc_joystick_driver);
> +
> +MODULE_DESCRIPTION("Input driver for joysticks connected over ADC");
> +MODULE_AUTHOR("Artur Rojek <contact@...ur-rojek.eu>");
> +MODULE_LICENSE("GPL");

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