drivers/input/joystick/adc-joystick.c

   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 <linux/unaligned.h>
  15
  16 struct adc_joystick_axis {
  17         u32 code;
  18         bool inverted;
  19 };
  20
  21 struct adc_joystick {
  22         struct input_dev *input;
  23         struct iio_cb_buffer *buffer;
  24         struct iio_channel *chans;
  25         unsigned int num_chans;
  26         struct adc_joystick_axis axes[] __counted_by(num_chans);
  27 };
  28
  29 static int adc_joystick_invert(struct input_dev *dev,
  30                                unsigned int axis, int val)
  31 {
  32         int min = input_abs_get_min(dev, axis);
  33         int max = input_abs_get_max(dev, axis);
  34
  35         return (max + min) - val;
  36 }
  37
  38 static void adc_joystick_poll(struct input_dev *input)
  39 {
  40         struct adc_joystick *joy = input_get_drvdata(input);
  41         int i, val, ret;
  42
  43         for (i = 0; i < joy->num_chans; i++) {
  44                 ret = iio_read_channel_raw(&joy->chans[i], &val);
  45                 if (ret < 0)
  46                         return;
  47                 if (joy->axes[i].inverted)
  48                         val = adc_joystick_invert(input, i, val);
  49                 input_report_abs(input, joy->axes[i].code, val);
  50         }
  51         input_sync(input);
  52 }
  53
  54 static int adc_joystick_handle(const void *data, void *private)
  55 {
  56         struct adc_joystick *joy = private;
  57         enum iio_endian endianness;
  58         int bytes, msb, val, idx, i;
  59         const u16 *data_u16;
  60         bool sign;
  61
  62         bytes = joy->chans[0].channel->scan_type.storagebits >> 3;
  63
  64         for (i = 0; i < joy->num_chans; ++i) {
  65                 idx = joy->chans[i].channel->scan_index;
  66                 endianness = joy->chans[i].channel->scan_type.endianness;
  67                 msb = joy->chans[i].channel->scan_type.realbits - 1;
  68                 sign = tolower(joy->chans[i].channel->scan_type.sign) == 's';
  69
  70                 switch (bytes) {
  71                 case 1:
  72                         val = ((const u8 *)data)[idx];
  73                         break;
  74                 case 2:
  75                         data_u16 = (const u16 *)data + idx;
  76
  77                         /*
  78                          * Data is aligned to the sample size by IIO core.
  79                          * Call `get_unaligned_xe16` to hide type casting.
  80                          */
  81                         if (endianness == IIO_BE)
  82                                 val = get_unaligned_be16(data_u16);
  83                         else if (endianness == IIO_LE)
  84                                 val = get_unaligned_le16(data_u16);
  85                         else /* IIO_CPU */
  86                                 val = *data_u16;
  87                         break;
  88                 default:
  89                         return -EINVAL;
  90                 }
  91
  92                 val >>= joy->chans[i].channel->scan_type.shift;
  93                 if (sign)
  94                         val = sign_extend32(val, msb);
  95                 else
  96                         val &= GENMASK(msb, 0);
  97                 if (joy->axes[i].inverted)
  98                         val = adc_joystick_invert(joy->input, i, val);
  99                 input_report_abs(joy->input, joy->axes[i].code, val);
 100         }
 101
 102         input_sync(joy->input);
 103
 104         return 0;
 105 }
 106
 107 static int adc_joystick_open(struct input_dev *dev)
 108 {
 109         struct adc_joystick *joy = input_get_drvdata(dev);
 110         struct device *devp = &dev->dev;
 111         int ret;
 112
 113         ret = iio_channel_start_all_cb(joy->buffer);
 114         if (ret)
 115                 dev_err(devp, "Unable to start callback buffer: %d\n", ret);
 116
 117         return ret;
 118 }
 119
 120 static void adc_joystick_close(struct input_dev *dev)
 121 {
 122         struct adc_joystick *joy = input_get_drvdata(dev);
 123
 124         iio_channel_stop_all_cb(joy->buffer);
 125 }
 126
 127 static void adc_joystick_cleanup(void *data)
 128 {
 129         iio_channel_release_all_cb(data);
 130 }
 131
 132 static int adc_joystick_set_axes(struct device *dev, struct adc_joystick *joy)
 133 {
 134         struct adc_joystick_axis *axes = joy->axes;
 135         s32 range[2], fuzz, flat;
 136         unsigned int num_axes;
 137         int error, i;
 138
 139         num_axes = device_get_child_node_count(dev);
 140         if (!num_axes) {
 141                 dev_err(dev, "Unable to find child nodes\n");
 142                 return -EINVAL;
 143         }
 144
 145         if (num_axes != joy->num_chans) {
 146                 dev_err(dev, "Got %d child nodes for %d channels\n",
 147                         num_axes, joy->num_chans);
 148                 return -EINVAL;
 149         }
 150
 151         device_for_each_child_node_scoped(dev, child) {
 152                 error = fwnode_property_read_u32(child, "reg", &i);
 153                 if (error) {
 154                         dev_err(dev, "reg invalid or missing\n");
 155                         return error;
 156                 }
 157
 158                 if (i >= num_axes) {
 159                         dev_err(dev, "No matching axis for reg %d\n", i);
 160                         return -EINVAL;
 161                 }
 162
 163                 error = fwnode_property_read_u32(child, "linux,code",
 164                                                  &axes[i].code);
 165                 if (error) {
 166                         dev_err(dev, "linux,code invalid or missing\n");
 167                         return error;
 168                 }
 169
 170                 error = fwnode_property_read_u32_array(child, "abs-range",
 171                                                        range, 2);
 172                 if (error) {
 173                         dev_err(dev, "abs-range invalid or missing\n");
 174                         return error;
 175                 }
 176
 177                 if (range[0] > range[1]) {
 178                         dev_dbg(dev, "abs-axis %d inverted\n", i);
 179                         axes[i].inverted = true;
 180                         swap(range[0], range[1]);
 181                 }
 182
 183                 if (fwnode_property_read_u32(child, "abs-fuzz", &fuzz))
 184                         fuzz = 0;
 185
 186                 if (fwnode_property_read_u32(child, "abs-flat", &flat))
 187                         flat = 0;
 188
 189                 input_set_abs_params(joy->input, axes[i].code,
 190                                      range[0], range[1], fuzz, flat);
 191         }
 192
 193         return 0;
 194 }
 195
 196
 197 static int adc_joystick_count_channels(struct device *dev,
 198                                        const struct iio_channel *chans,
 199                                        bool polled,
 200                                        unsigned int *num_chans)
 201 {
 202         int bits;
 203         int i;
 204
 205         /*
 206          * Count how many channels we got. NULL terminated.
 207          * Do not check the storage size if using polling.
 208          */
 209         for (i = 0; chans[i].indio_dev; i++) {
 210                 if (polled)
 211                         continue;
 212                 bits = chans[i].channel->scan_type.storagebits;
 213                 if (!bits || bits > 16) {
 214                         dev_err(dev, "Unsupported channel storage size\n");
 215                         return -EINVAL;
 216                 }
 217                 if (bits != chans[0].channel->scan_type.storagebits) {
 218                         dev_err(dev, "Channels must have equal storage size\n");
 219                         return -EINVAL;
 220                 }
 221         }
 222
 223         *num_chans = i;
 224         return 0;
 225 }
 226
 227 static int adc_joystick_probe(struct platform_device *pdev)
 228 {
 229         struct device *dev = &pdev->dev;
 230         struct iio_channel *chans;
 231         struct adc_joystick *joy;
 232         struct input_dev *input;
 233         unsigned int poll_interval = 0;
 234         unsigned int num_chans;
 235         int error;
 236
 237         chans = devm_iio_channel_get_all(dev);
 238         error = PTR_ERR_OR_ZERO(chans);
 239         if (error) {
 240                 if (error != -EPROBE_DEFER)
 241                         dev_err(dev, "Unable to get IIO channels");
 242                 return error;
 243         }
 244
 245         error = device_property_read_u32(dev, "poll-interval", &poll_interval);
 246         if (error) {
 247                 /* -EINVAL means the property is absent. */
 248                 if (error != -EINVAL)
 249                         return error;
 250         } else if (poll_interval == 0) {
 251                 dev_err(dev, "Unable to get poll-interval\n");
 252                 return -EINVAL;
 253         }
 254
 255         error = adc_joystick_count_channels(dev, chans, poll_interval != 0,
 256                                             &num_chans);
 257         if (error)
 258                 return error;
 259
 260         joy = devm_kzalloc(dev, struct_size(joy, axes, num_chans), GFP_KERNEL);
 261         if (!joy)
 262                 return -ENOMEM;
 263
 264         joy->chans = chans;
 265         joy->num_chans = num_chans;
 266
 267         input = devm_input_allocate_device(dev);
 268         if (!input) {
 269                 dev_err(dev, "Unable to allocate input device\n");
 270                 return -ENOMEM;
 271         }
 272
 273         joy->input = input;
 274         input->name = pdev->name;
 275         input->id.bustype = BUS_HOST;
 276
 277         error = adc_joystick_set_axes(dev, joy);
 278         if (error)
 279                 return error;
 280
 281         if (poll_interval != 0) {
 282                 input_setup_polling(input, adc_joystick_poll);
 283                 input_set_poll_interval(input, poll_interval);
 284         } else {
 285                 input->open = adc_joystick_open;
 286                 input->close = adc_joystick_close;
 287
 288                 joy->buffer = iio_channel_get_all_cb(dev, adc_joystick_handle,
 289                                                      joy);
 290                 if (IS_ERR(joy->buffer)) {
 291                         dev_err(dev, "Unable to allocate callback buffer\n");
 292                         return PTR_ERR(joy->buffer);
 293                 }
 294
 295                 error = devm_add_action_or_reset(dev, adc_joystick_cleanup,
 296                                                  joy->buffer);
 297                 if (error)  {
 298                         dev_err(dev, "Unable to add action\n");
 299                         return error;
 300                 }
 301         }
 302
 303         input_set_drvdata(input, joy);
 304
 305         error = input_register_device(input);
 306         if (error) {
 307                 dev_err(dev, "Unable to register input device\n");
 308                 return error;
 309         }
 310
 311         return 0;
 312 }
 313
 314 static const struct of_device_id adc_joystick_of_match[] = {
 315         { .compatible = "adc-joystick", },
 316         { }
 317 };
 318 MODULE_DEVICE_TABLE(of, adc_joystick_of_match);
 319
 320 static struct platform_driver adc_joystick_driver = {
 321         .driver = {
 322                 .name = "adc-joystick",
 323                 .of_match_table = adc_joystick_of_match,
 324         },
 325         .probe = adc_joystick_probe,
 326 };
 327 module_platform_driver(adc_joystick_driver);
 328
 329 MODULE_DESCRIPTION("Input driver for joysticks connected over ADC");
 330 MODULE_AUTHOR("Artur Rojek <contact@artur-rojek.eu>");
 331 MODULE_LICENSE("GPL");