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