drivers/hid/hid-uclogic-params.h

   1 /* SPDX-License-Identifier: GPL-2.0+ */
   2 /*
   3  *  HID driver for UC-Logic devices not fully compliant with HID standard
   4  *  - tablet initialization and parameter retrieval
   5  *
   6  *  Copyright (c) 2018 Nikolai Kondrashov
   7  */
   8
   9 /*
  10  * This program is free software; you can redistribute it and/or modify it
  11  * under the terms of the GNU General Public License as published by the Free
  12  * Software Foundation; either version 2 of the License, or (at your option)
  13  * any later version.
  14  */
  15
  16 #ifndef _HID_UCLOGIC_PARAMS_H
  17 #define _HID_UCLOGIC_PARAMS_H
  18
  19 #include <linux/usb.h>
  20 #include <linux/hid.h>
  21
  22 /* Types of pen in-range reporting */
  23 enum uclogic_params_pen_inrange {
  24         /* Normal reports: zero - out of proximity, one - in proximity */
  25         UCLOGIC_PARAMS_PEN_INRANGE_NORMAL = 0,
  26         /* Inverted reports: zero - in proximity, one - out of proximity */
  27         UCLOGIC_PARAMS_PEN_INRANGE_INVERTED,
  28         /* No reports */
  29         UCLOGIC_PARAMS_PEN_INRANGE_NONE,
  30 };
  31
  32 /* Convert a pen in-range reporting type to a string */
  33 extern const char *uclogic_params_pen_inrange_to_str(
  34                         enum uclogic_params_pen_inrange inrange);
  35
  36 /*
  37  * Tablet interface's pen input parameters.
  38  *
  39  * Must use declarative (descriptive) language, not imperative, to simplify
  40  * understanding and maintain consistency.
  41  *
  42  * Noop (preserving functionality) when filled with zeroes.
  43  */
  44 struct uclogic_params_pen {
  45         /*
  46          * Pointer to report descriptor describing the inputs.
  47          * Allocated with kmalloc.
  48          */
  49         __u8 *desc_ptr;
  50         /*
  51          * Size of the report descriptor.
  52          * Only valid, if "desc_ptr" is not NULL.
  53          */
  54         unsigned int desc_size;
  55         /* Report ID, if reports should be tweaked, zero if not */
  56         unsigned int id;
  57         /* Type of in-range reporting, only valid if "id" is not zero */
  58         enum uclogic_params_pen_inrange inrange;
  59         /*
  60          * True, if reports include fragmented high resolution coords, with
  61          * high-order X and then Y bytes following the pressure field.
  62          * Only valid if "id" is not zero.
  63          */
  64         bool fragmented_hires;
  65 };
  66
  67 /*
  68  * Parameters of frame control inputs of a tablet interface.
  69  *
  70  * Must use declarative (descriptive) language, not imperative, to simplify
  71  * understanding and maintain consistency.
  72  *
  73  * Noop (preserving functionality) when filled with zeroes.
  74  */
  75 struct uclogic_params_frame {
  76         /*
  77          * Pointer to report descriptor describing the inputs.
  78          * Allocated with kmalloc.
  79          */
  80         __u8 *desc_ptr;
  81         /*
  82          * Size of the report descriptor.
  83          * Only valid, if "desc_ptr" is not NULL.
  84          */
  85         unsigned int desc_size;
  86         /*
  87          * Report ID, if reports should be tweaked, zero if not.
  88          */
  89         unsigned int id;
  90         /*
  91          * Number of the least-significant bit of the 2-bit state of a rotary
  92          * encoder, in the report. Cannot point to a 2-bit field crossing a
  93          * byte boundary. Zero if not present. Only valid if "id" is not zero.
  94          */
  95         unsigned int re_lsb;
  96         /*
  97          * Offset of the Wacom-style device ID byte in the report, to be set
  98          * to pad device ID (0xf), for compatibility with Wacom drivers. Zero
  99          * if no changes to the report should be made. Only valid if "id" is
 100          * not zero.
 101          */
 102         unsigned int dev_id_byte;
 103 };
 104
 105 /*
 106  * Tablet interface report parameters.
 107  *
 108  * Must use declarative (descriptive) language, not imperative, to simplify
 109  * understanding and maintain consistency.
 110  *
 111  * When filled with zeros represents a "noop" configuration - passes all
 112  * reports unchanged and lets the generic HID driver handle everything.
 113  *
 114  * The resulting device report descriptor is assembled from all the report
 115  * descriptor parts referenced by the structure. No order of assembly should
 116  * be assumed. The structure represents original device report descriptor if
 117  * all the parts are NULL.
 118  */
 119 struct uclogic_params {
 120         /*
 121          * True if the whole interface is invalid, false otherwise.
 122          */
 123         bool invalid;
 124         /*
 125          * Pointer to the common part of the replacement report descriptor,
 126          * allocated with kmalloc. NULL if no common part is needed.
 127          * Only valid, if "invalid" is false.
 128          */
 129         __u8 *desc_ptr;
 130         /*
 131          * Size of the common part of the replacement report descriptor.
 132          * Only valid, if "desc_ptr" is not NULL.
 133          */
 134         unsigned int desc_size;
 135         /*
 136          * True, if pen usage in report descriptor is invalid, when present.
 137          * Only valid, if "invalid" is false.
 138          */
 139         bool pen_unused;
 140         /*
 141          * Pen parameters and optional report descriptor part.
 142          * Only valid if "pen_unused" is valid and false.
 143          */
 144         struct uclogic_params_pen pen;
 145         /*
 146          * Frame control parameters and optional report descriptor part.
 147          * Only valid, if "invalid" is false.
 148          */
 149         struct uclogic_params_frame frame;
 150         /*
 151          * Bitmask matching frame controls "sub-report" flag in the second
 152          * byte of the pen report, or zero if it's not expected.
 153          * Only valid if both "pen" and "frame" are valid, and "frame.id" is
 154          * not zero.
 155          */
 156         __u8 pen_frame_flag;
 157 };
 158
 159 /* Initialize a tablet interface and discover its parameters */
 160 extern int uclogic_params_init(struct uclogic_params *params,
 161                                 struct hid_device *hdev);
 162
 163 /* Tablet interface parameters *printf format string */
 164 #define UCLOGIC_PARAMS_FMT_STR \
 165                 ".invalid = %s\n"                   \
 166                 ".desc_ptr = %p\n"                  \
 167                 ".desc_size = %u\n"                 \
 168                 ".pen_unused = %s\n"                \
 169                 ".pen.desc_ptr = %p\n"              \
 170                 ".pen.desc_size = %u\n"             \
 171                 ".pen.id = %u\n"                    \
 172                 ".pen.inrange = %s\n"               \
 173                 ".pen.fragmented_hires = %s\n"      \
 174                 ".frame.desc_ptr = %p\n"            \
 175                 ".frame.desc_size = %u\n"           \
 176                 ".frame.id = %u\n"                  \
 177                 ".frame.re_lsb = %u\n"              \
 178                 ".frame.dev_id_byte = %u\n"         \
 179                 ".pen_frame_flag = 0x%02x\n"
 180
 181 /* Tablet interface parameters *printf format arguments */
 182 #define UCLOGIC_PARAMS_FMT_ARGS(_params) \
 183                 ((_params)->invalid ? "true" : "false"),                    \
 184                 (_params)->desc_ptr,                                        \
 185                 (_params)->desc_size,                                       \
 186                 ((_params)->pen_unused ? "true" : "false"),                 \
 187                 (_params)->pen.desc_ptr,                                    \
 188                 (_params)->pen.desc_size,                                   \
 189                 (_params)->pen.id,                                          \
 190                 uclogic_params_pen_inrange_to_str((_params)->pen.inrange),  \
 191                 ((_params)->pen.fragmented_hires ? "true" : "false"),       \
 192                 (_params)->frame.desc_ptr,                                  \
 193                 (_params)->frame.desc_size,                                 \
 194                 (_params)->frame.id,                                        \
 195                 (_params)->frame.re_lsb,                                    \
 196                 (_params)->frame.dev_id_byte,                               \
 197                 (_params)->pen_frame_flag
 198
 199 /* Get a replacement report descriptor for a tablet's interface. */
 200 extern int uclogic_params_get_desc(const struct uclogic_params *params,
 201                                         __u8 **pdesc,
 202                                         unsigned int *psize);
 203
 204 /* Free resources used by tablet interface's parameters */
 205 extern void uclogic_params_cleanup(struct uclogic_params *params);
 206
 207 #endif /* _HID_UCLOGIC_PARAMS_H */