linux/drivers/input/joystick/adc-joystick.c
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   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * Input driver for joysticks connected over ADC.
   4 * Copyright (c) 2019-2020 Artur Rojek <contact@artur-rojek.eu>
   5 */
   6#include <linux/ctype.h>
   7#include <linux/input.h>
   8#include <linux/iio/iio.h>
   9#include <linux/iio/consumer.h>
  10#include <linux/module.h>
  11#include <linux/platform_device.h>
  12#include <linux/property.h>
  13
  14#include <asm/unaligned.h>
  15
  16struct adc_joystick_axis {
  17        u32 code;
  18        s32 range[2];
  19        s32 fuzz;
  20        s32 flat;
  21};
  22
  23struct adc_joystick {
  24        struct input_dev *input;
  25        struct iio_cb_buffer *buffer;
  26        struct adc_joystick_axis *axes;
  27        struct iio_channel *chans;
  28        int num_chans;
  29};
  30
  31static int adc_joystick_handle(const void *data, void *private)
  32{
  33        struct adc_joystick *joy = private;
  34        enum iio_endian endianness;
  35        int bytes, msb, val, idx, i;
  36        const u16 *data_u16;
  37        bool sign;
  38
  39        bytes = joy->chans[0].channel->scan_type.storagebits >> 3;
  40
  41        for (i = 0; i < joy->num_chans; ++i) {
  42                idx = joy->chans[i].channel->scan_index;
  43                endianness = joy->chans[i].channel->scan_type.endianness;
  44                msb = joy->chans[i].channel->scan_type.realbits - 1;
  45                sign = tolower(joy->chans[i].channel->scan_type.sign) == 's';
  46
  47                switch (bytes) {
  48                case 1:
  49                        val = ((const u8 *)data)[idx];
  50                        break;
  51                case 2:
  52                        data_u16 = (const u16 *)data + idx;
  53
  54                        /*
  55                         * Data is aligned to the sample size by IIO core.
  56                         * Call `get_unaligned_xe16` to hide type casting.
  57                         */
  58                        if (endianness == IIO_BE)
  59                                val = get_unaligned_be16(data_u16);
  60                        else if (endianness == IIO_LE)
  61                                val = get_unaligned_le16(data_u16);
  62                        else /* IIO_CPU */
  63                                val = *data_u16;
  64                        break;
  65                default:
  66                        return -EINVAL;
  67                }
  68
  69                val >>= joy->chans[i].channel->scan_type.shift;
  70                if (sign)
  71                        val = sign_extend32(val, msb);
  72                else
  73                        val &= GENMASK(msb, 0);
  74                input_report_abs(joy->input, joy->axes[i].code, val);
  75        }
  76
  77        input_sync(joy->input);
  78
  79        return 0;
  80}
  81
  82static int adc_joystick_open(struct input_dev *dev)
  83{
  84        struct adc_joystick *joy = input_get_drvdata(dev);
  85        struct device *devp = &dev->dev;
  86        int ret;
  87
  88        ret = iio_channel_start_all_cb(joy->buffer);
  89        if (ret)
  90                dev_err(devp, "Unable to start callback buffer: %d\n", ret);
  91
  92        return ret;
  93}
  94
  95static void adc_joystick_close(struct input_dev *dev)
  96{
  97        struct adc_joystick *joy = input_get_drvdata(dev);
  98
  99        iio_channel_stop_all_cb(joy->buffer);
 100}
 101
 102static void adc_joystick_cleanup(void *data)
 103{
 104        iio_channel_release_all_cb(data);
 105}
 106
 107static int adc_joystick_set_axes(struct device *dev, struct adc_joystick *joy)
 108{
 109        struct adc_joystick_axis *axes;
 110        struct fwnode_handle *child;
 111        int num_axes, error, i;
 112
 113        num_axes = device_get_child_node_count(dev);
 114        if (!num_axes) {
 115                dev_err(dev, "Unable to find child nodes\n");
 116                return -EINVAL;
 117        }
 118
 119        if (num_axes != joy->num_chans) {
 120                dev_err(dev, "Got %d child nodes for %d channels\n",
 121                        num_axes, joy->num_chans);
 122                return -EINVAL;
 123        }
 124
 125        axes = devm_kmalloc_array(dev, num_axes, sizeof(*axes), GFP_KERNEL);
 126        if (!axes)
 127                return -ENOMEM;
 128
 129        device_for_each_child_node(dev, child) {
 130                error = fwnode_property_read_u32(child, "reg", &i);
 131                if (error) {
 132                        dev_err(dev, "reg invalid or missing\n");
 133                        goto err_fwnode_put;
 134                }
 135
 136                if (i >= num_axes) {
 137                        error = -EINVAL;
 138                        dev_err(dev, "No matching axis for reg %d\n", i);
 139                        goto err_fwnode_put;
 140                }
 141
 142                error = fwnode_property_read_u32(child, "linux,code",
 143                                                 &axes[i].code);
 144                if (error) {
 145                        dev_err(dev, "linux,code invalid or missing\n");
 146                        goto err_fwnode_put;
 147                }
 148
 149                error = fwnode_property_read_u32_array(child, "abs-range",
 150                                                       axes[i].range, 2);
 151                if (error) {
 152                        dev_err(dev, "abs-range invalid or missing\n");
 153                        goto err_fwnode_put;
 154                }
 155
 156                fwnode_property_read_u32(child, "abs-fuzz", &axes[i].fuzz);
 157                fwnode_property_read_u32(child, "abs-flat", &axes[i].flat);
 158
 159                input_set_abs_params(joy->input, axes[i].code,
 160                                     axes[i].range[0], axes[i].range[1],
 161                                     axes[i].fuzz, axes[i].flat);
 162                input_set_capability(joy->input, EV_ABS, axes[i].code);
 163        }
 164
 165        joy->axes = axes;
 166
 167        return 0;
 168
 169err_fwnode_put:
 170        fwnode_handle_put(child);
 171        return error;
 172}
 173
 174static int adc_joystick_probe(struct platform_device *pdev)
 175{
 176        struct device *dev = &pdev->dev;
 177        struct adc_joystick *joy;
 178        struct input_dev *input;
 179        int error;
 180        int bits;
 181        int i;
 182
 183        joy = devm_kzalloc(dev, sizeof(*joy), GFP_KERNEL);
 184        if (!joy)
 185                return -ENOMEM;
 186
 187        joy->chans = devm_iio_channel_get_all(dev);
 188        if (IS_ERR(joy->chans)) {
 189                error = PTR_ERR(joy->chans);
 190                if (error != -EPROBE_DEFER)
 191                        dev_err(dev, "Unable to get IIO channels");
 192                return error;
 193        }
 194
 195        /* Count how many channels we got. NULL terminated. */
 196        for (i = 0; joy->chans[i].indio_dev; i++) {
 197                bits = joy->chans[i].channel->scan_type.storagebits;
 198                if (!bits || bits > 16) {
 199                        dev_err(dev, "Unsupported channel storage size\n");
 200                        return -EINVAL;
 201                }
 202                if (bits != joy->chans[0].channel->scan_type.storagebits) {
 203                        dev_err(dev, "Channels must have equal storage size\n");
 204                        return -EINVAL;
 205                }
 206        }
 207        joy->num_chans = i;
 208
 209        input = devm_input_allocate_device(dev);
 210        if (!input) {
 211                dev_err(dev, "Unable to allocate input device\n");
 212                return -ENOMEM;
 213        }
 214
 215        joy->input = input;
 216        input->name = pdev->name;
 217        input->id.bustype = BUS_HOST;
 218        input->open = adc_joystick_open;
 219        input->close = adc_joystick_close;
 220
 221        error = adc_joystick_set_axes(dev, joy);
 222        if (error)
 223                return error;
 224
 225        input_set_drvdata(input, joy);
 226        error = input_register_device(input);
 227        if (error) {
 228                dev_err(dev, "Unable to register input device\n");
 229                return error;
 230        }
 231
 232        joy->buffer = iio_channel_get_all_cb(dev, adc_joystick_handle, joy);
 233        if (IS_ERR(joy->buffer)) {
 234                dev_err(dev, "Unable to allocate callback buffer\n");
 235                return PTR_ERR(joy->buffer);
 236        }
 237
 238        error = devm_add_action_or_reset(dev, adc_joystick_cleanup, joy->buffer);
 239        if (error)  {
 240                dev_err(dev, "Unable to add action\n");
 241                return error;
 242        }
 243
 244        return 0;
 245}
 246
 247static const struct of_device_id adc_joystick_of_match[] = {
 248        { .compatible = "adc-joystick", },
 249        { }
 250};
 251MODULE_DEVICE_TABLE(of, adc_joystick_of_match);
 252
 253static struct platform_driver adc_joystick_driver = {
 254        .driver = {
 255                .name = "adc-joystick",
 256                .of_match_table = adc_joystick_of_match,
 257        },
 258        .probe = adc_joystick_probe,
 259};
 260module_platform_driver(adc_joystick_driver);
 261
 262MODULE_DESCRIPTION("Input driver for joysticks connected over ADC");
 263MODULE_AUTHOR("Artur Rojek <contact@artur-rojek.eu>");
 264MODULE_LICENSE("GPL");
 265