1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
|
// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Copyright (C) IBM Corporation 2020
*/
#include <linux/i2c.h>
#include <linux/init.h>
#include <linux/input.h>
#include <linux/kernel.h>
#include <linux/limits.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/spinlock.h>
#define DEVICE_NAME "ibm-panel"
#define PANEL_KEYCODES_COUNT 3
struct ibm_panel {
u8 idx;
u8 command[11];
u32 keycodes[PANEL_KEYCODES_COUNT];
spinlock_t lock; /* protects writes to idx and command */
struct input_dev *input;
};
static u8 ibm_panel_calculate_checksum(struct ibm_panel *panel)
{
u8 chksum;
u16 sum = 0;
unsigned int i;
for (i = 0; i < sizeof(panel->command) - 1; ++i) {
sum += panel->command[i];
if (sum & 0xff00) {
sum &= 0xff;
sum++;
}
}
chksum = sum & 0xff;
chksum = ~chksum;
chksum++;
return chksum;
}
static void ibm_panel_process_command(struct ibm_panel *panel)
{
u8 button;
u8 chksum;
if (panel->command[0] != 0xff && panel->command[1] != 0xf0) {
dev_dbg(&panel->input->dev, "command invalid: %02x %02x\n",
panel->command[0], panel->command[1]);
return;
}
chksum = ibm_panel_calculate_checksum(panel);
if (chksum != panel->command[sizeof(panel->command) - 1]) {
dev_dbg(&panel->input->dev,
"command failed checksum: %u != %u\n", chksum,
panel->command[sizeof(panel->command) - 1]);
return;
}
button = panel->command[2] & 0xf;
if (button < PANEL_KEYCODES_COUNT) {
input_report_key(panel->input, panel->keycodes[button],
!(panel->command[2] & 0x80));
input_sync(panel->input);
} else {
dev_dbg(&panel->input->dev, "unknown button %u\n",
button);
}
}
static int ibm_panel_i2c_slave_cb(struct i2c_client *client,
enum i2c_slave_event event, u8 *val)
{
unsigned long flags;
struct ibm_panel *panel = i2c_get_clientdata(client);
dev_dbg(&panel->input->dev, "event: %u data: %02x\n", event, *val);
spin_lock_irqsave(&panel->lock, flags);
switch (event) {
case I2C_SLAVE_STOP:
if (panel->idx == sizeof(panel->command))
ibm_panel_process_command(panel);
else
dev_dbg(&panel->input->dev,
"command incorrect size %u\n", panel->idx);
fallthrough;
case I2C_SLAVE_WRITE_REQUESTED:
panel->idx = 0;
break;
case I2C_SLAVE_WRITE_RECEIVED:
if (panel->idx < sizeof(panel->command))
panel->command[panel->idx++] = *val;
else
/*
* The command is too long and therefore invalid, so set the index
* to it's largest possible value. When a STOP is finally received,
* the command will be rejected upon processing.
*/
panel->idx = U8_MAX;
break;
case I2C_SLAVE_READ_REQUESTED:
case I2C_SLAVE_READ_PROCESSED:
*val = 0xff;
break;
default:
break;
}
spin_unlock_irqrestore(&panel->lock, flags);
return 0;
}
static int ibm_panel_probe(struct i2c_client *client)
{
struct ibm_panel *panel;
int i;
int error;
panel = devm_kzalloc(&client->dev, sizeof(*panel), GFP_KERNEL);
if (!panel)
return -ENOMEM;
spin_lock_init(&panel->lock);
panel->input = devm_input_allocate_device(&client->dev);
if (!panel->input)
return -ENOMEM;
panel->input->name = client->name;
panel->input->id.bustype = BUS_I2C;
error = device_property_read_u32_array(&client->dev,
"linux,keycodes",
panel->keycodes,
PANEL_KEYCODES_COUNT);
if (error) {
/*
* Use gamepad buttons as defaults for compatibility with
* existing applications.
*/
panel->keycodes[0] = BTN_NORTH;
panel->keycodes[1] = BTN_SOUTH;
panel->keycodes[2] = BTN_SELECT;
}
for (i = 0; i < PANEL_KEYCODES_COUNT; ++i)
input_set_capability(panel->input, EV_KEY, panel->keycodes[i]);
error = input_register_device(panel->input);
if (error) {
dev_err(&client->dev,
"Failed to register input device: %d\n", error);
return error;
}
i2c_set_clientdata(client, panel);
error = i2c_slave_register(client, ibm_panel_i2c_slave_cb);
if (error) {
dev_err(&client->dev,
"Failed to register as i2c slave: %d\n", error);
return error;
}
return 0;
}
static void ibm_panel_remove(struct i2c_client *client)
{
i2c_slave_unregister(client);
}
static const struct of_device_id ibm_panel_match[] = {
{ .compatible = "ibm,op-panel" },
{ }
};
MODULE_DEVICE_TABLE(of, ibm_panel_match);
static struct i2c_driver ibm_panel_driver = {
.driver = {
.name = DEVICE_NAME,
.of_match_table = ibm_panel_match,
},
.probe_new = ibm_panel_probe,
.remove = ibm_panel_remove,
};
module_i2c_driver(ibm_panel_driver);
MODULE_AUTHOR("Eddie James <eajames@linux.ibm.com>");
MODULE_DESCRIPTION("IBM Operation Panel Driver");
MODULE_LICENSE("GPL");
|
