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 */
208