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 };
  30
  31 static 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
  82 static 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
  95 static 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
 102 static void adc_joystick_cleanup(void *data)
 103 {
 104         iio_channel_release_all_cb(data);
 105 }
 106
 107 static 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
 169 err_fwnode_put:
 170         fwnode_handle_put(child);
 171         return error;
 172 }
 173
 174 static 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
 247 static const struct of_device_id adc_joystick_of_match[] = {
 248         { .compatible = "adc-joystick", },
 249         { }
 250 };
 251 MODULE_DEVICE_TABLE(of, adc_joystick_of_match);
 252
 253 static 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 };
 260 module_platform_driver(adc_joystick_driver);
 261
 262 MODULE_DESCRIPTION("Input driver for joysticks connected over ADC");
 263 MODULE_AUTHOR("Artur Rojek <contact@artur-rojek.eu>");
 264 MODULE_LICENSE("GPL");