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