linux/drivers/input/joystick/fsia6b.c
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   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * FS-iA6B iBus RC receiver driver
   4 *
   5 * This driver provides all 14 channels of the FlySky FS-ia6B RC receiver
   6 * as analog values.
   7 *
   8 * Additionally, the channels can be converted to discrete switch values.
   9 * By default, it is configured for the offical FS-i6 remote control.
  10 * If you use a different hardware configuration, you can configure it
  11 * using the `switch_config` parameter.
  12 */
  13
  14#include <linux/device.h>
  15#include <linux/input.h>
  16#include <linux/kernel.h>
  17#include <linux/module.h>
  18#include <linux/serio.h>
  19#include <linux/slab.h>
  20#include <linux/types.h>
  21
  22#define DRIVER_DESC             "FS-iA6B iBus RC receiver"
  23
  24MODULE_AUTHOR("Markus Koch <markus@notsyncing.net>");
  25MODULE_DESCRIPTION(DRIVER_DESC);
  26MODULE_LICENSE("GPL");
  27
  28#define IBUS_SERVO_COUNT        14
  29
  30static char *switch_config = "00000022320000";
  31module_param(switch_config, charp, 0444);
  32MODULE_PARM_DESC(switch_config,
  33                 "Amount of switch positions per channel (14 characters, 0-3)");
  34
  35static int fsia6b_axes[IBUS_SERVO_COUNT] = {
  36        ABS_X, ABS_Y,
  37        ABS_Z, ABS_RX,
  38        ABS_RY, ABS_RZ,
  39        ABS_HAT0X, ABS_HAT0Y,
  40        ABS_HAT1X, ABS_HAT1Y,
  41        ABS_HAT2X, ABS_HAT2Y,
  42        ABS_HAT3X, ABS_HAT3Y
  43};
  44
  45enum ibus_state { SYNC, COLLECT, PROCESS };
  46
  47struct ibus_packet {
  48        enum ibus_state state;
  49
  50        int offset;
  51        u16 ibuf;
  52        u16 channel[IBUS_SERVO_COUNT];
  53};
  54
  55struct fsia6b {
  56        struct input_dev *dev;
  57        struct ibus_packet packet;
  58
  59        char phys[32];
  60};
  61
  62static irqreturn_t fsia6b_serio_irq(struct serio *serio,
  63                                    unsigned char data, unsigned int flags)
  64{
  65        struct fsia6b *fsia6b = serio_get_drvdata(serio);
  66        int i;
  67        int sw_state;
  68        int sw_id = BTN_0;
  69
  70        fsia6b->packet.ibuf = (data << 8) | ((fsia6b->packet.ibuf >> 8) & 0xFF);
  71
  72        switch (fsia6b->packet.state) {
  73        case SYNC:
  74                if (fsia6b->packet.ibuf == 0x4020)
  75                        fsia6b->packet.state = COLLECT;
  76                break;
  77
  78        case COLLECT:
  79                fsia6b->packet.state = PROCESS;
  80                break;
  81
  82        case PROCESS:
  83                fsia6b->packet.channel[fsia6b->packet.offset] =
  84                                fsia6b->packet.ibuf;
  85                fsia6b->packet.offset++;
  86
  87                if (fsia6b->packet.offset == IBUS_SERVO_COUNT) {
  88                        fsia6b->packet.offset = 0;
  89                        fsia6b->packet.state = SYNC;
  90                        for (i = 0; i < IBUS_SERVO_COUNT; ++i) {
  91                                input_report_abs(fsia6b->dev, fsia6b_axes[i],
  92                                                 fsia6b->packet.channel[i]);
  93
  94                                sw_state = 0;
  95                                if (fsia6b->packet.channel[i] > 1900)
  96                                        sw_state = 1;
  97                                else if (fsia6b->packet.channel[i] < 1100)
  98                                        sw_state = 2;
  99
 100                                switch (switch_config[i]) {
 101                                case '3':
 102                                        input_report_key(fsia6b->dev,
 103                                                         sw_id++,
 104                                                         sw_state == 0);
 105                                        fallthrough;
 106                                case '2':
 107                                        input_report_key(fsia6b->dev,
 108                                                         sw_id++,
 109                                                         sw_state == 1);
 110                                        fallthrough;
 111                                case '1':
 112                                        input_report_key(fsia6b->dev,
 113                                                         sw_id++,
 114                                                         sw_state == 2);
 115                                }
 116                        }
 117                        input_sync(fsia6b->dev);
 118                } else {
 119                        fsia6b->packet.state = COLLECT;
 120                }
 121                break;
 122        }
 123
 124        return IRQ_HANDLED;
 125}
 126
 127static int fsia6b_serio_connect(struct serio *serio, struct serio_driver *drv)
 128{
 129        struct fsia6b *fsia6b;
 130        struct input_dev *input_dev;
 131        int err;
 132        int i, j;
 133        int sw_id = 0;
 134
 135        fsia6b = kzalloc(sizeof(*fsia6b), GFP_KERNEL);
 136        if (!fsia6b)
 137                return -ENOMEM;
 138
 139        fsia6b->packet.ibuf = 0;
 140        fsia6b->packet.offset = 0;
 141        fsia6b->packet.state = SYNC;
 142
 143        serio_set_drvdata(serio, fsia6b);
 144
 145        input_dev = input_allocate_device();
 146        if (!input_dev) {
 147                err = -ENOMEM;
 148                goto fail1;
 149        }
 150        fsia6b->dev = input_dev;
 151
 152        snprintf(fsia6b->phys, sizeof(fsia6b->phys), "%s/input0", serio->phys);
 153
 154        input_dev->name = DRIVER_DESC;
 155        input_dev->phys = fsia6b->phys;
 156        input_dev->id.bustype = BUS_RS232;
 157        input_dev->id.vendor = SERIO_FSIA6B;
 158        input_dev->id.product = serio->id.id;
 159        input_dev->id.version = 0x0100;
 160        input_dev->dev.parent = &serio->dev;
 161
 162        for (i = 0; i < IBUS_SERVO_COUNT; i++)
 163                input_set_abs_params(input_dev, fsia6b_axes[i],
 164                                     1000, 2000, 2, 2);
 165
 166        /* Register switch configuration */
 167        for (i = 0; i < IBUS_SERVO_COUNT; i++) {
 168                if (switch_config[i] < '0' || switch_config[i] > '3') {
 169                        dev_err(&fsia6b->dev->dev,
 170                                "Invalid switch configuration supplied for fsia6b.\n");
 171                        err = -EINVAL;
 172                        goto fail2;
 173                }
 174
 175                for (j = '1'; j <= switch_config[i]; j++) {
 176                        input_set_capability(input_dev, EV_KEY, BTN_0 + sw_id);
 177                        sw_id++;
 178                }
 179        }
 180
 181        err = serio_open(serio, drv);
 182        if (err)
 183                goto fail2;
 184
 185        err = input_register_device(fsia6b->dev);
 186        if (err)
 187                goto fail3;
 188
 189        return 0;
 190
 191fail3:  serio_close(serio);
 192fail2:  input_free_device(input_dev);
 193fail1:  serio_set_drvdata(serio, NULL);
 194        kfree(fsia6b);
 195        return err;
 196}
 197
 198static void fsia6b_serio_disconnect(struct serio *serio)
 199{
 200        struct fsia6b *fsia6b = serio_get_drvdata(serio);
 201
 202        serio_close(serio);
 203        serio_set_drvdata(serio, NULL);
 204        input_unregister_device(fsia6b->dev);
 205        kfree(fsia6b);
 206}
 207
 208static const struct serio_device_id fsia6b_serio_ids[] = {
 209        {
 210                .type   = SERIO_RS232,
 211                .proto  = SERIO_FSIA6B,
 212                .id     = SERIO_ANY,
 213                .extra  = SERIO_ANY,
 214        },
 215        { 0 }
 216};
 217
 218MODULE_DEVICE_TABLE(serio, fsia6b_serio_ids);
 219
 220static struct serio_driver fsia6b_serio_drv = {
 221        .driver         = {
 222                .name   = "fsia6b"
 223        },
 224        .description    = DRIVER_DESC,
 225        .id_table       = fsia6b_serio_ids,
 226        .interrupt      = fsia6b_serio_irq,
 227        .connect        = fsia6b_serio_connect,
 228        .disconnect     = fsia6b_serio_disconnect
 229};
 230
 231module_serio_driver(fsia6b_serio_drv)
 232