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 */
23enum 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 */
33extern 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 */
44struct 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 */
75struct 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 */
119struct 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 */
160extern 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. */
200extern 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 */
205extern void uclogic_params_cleanup(struct uclogic_params *params);
206
207#endif /* _HID_UCLOGIC_PARAMS_H */
208