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
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
|
/*
* GRUB -- GRand Unified Bootloader
*
* Copyright (C) 2012 Google Inc.
* Copyright (C) 2016 Free Software Foundation, Inc.
*
* This is based on depthcharge code.
*
* GRUB is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* GRUB is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with GRUB. If not, see <http://www.gnu.org/licenses/>.
*/
#include <grub/mm.h>
#include <grub/time.h>
#include <grub/misc.h>
#include <grub/arm/cros_ec.h>
#include <grub/fdtbus.h>
static const grub_uint64_t FRAMING_TIMEOUT_MS = 300;
static const grub_uint8_t EC_FRAMING_BYTE = 0xec;
#define EC_CMD_MKBP_STATE 0x60
#define EC_CMD_VERSION0 0xdc
static grub_uint64_t last_transfer;
static void
stop_bus (const struct grub_fdtbus_dev *spi)
{
spi->driver->stop (spi);
last_transfer = grub_get_time_ms ();
}
static int
wait_for_frame (const struct grub_fdtbus_dev *spi)
{
grub_uint64_t start = grub_get_time_ms ();
grub_uint8_t byte;
do
{
if (spi->driver->receive (spi, &byte, 1))
return -1;
if (byte != EC_FRAMING_BYTE &&
grub_get_time_ms () - start > FRAMING_TIMEOUT_MS)
{
grub_dprintf ("cros", "Timeout waiting for framing byte.\n");
return -1;
}
}
while (byte != EC_FRAMING_BYTE);
return 0;
}
/*
* Calculate a simple 8-bit checksum of a data block
*
* @param data Data block to checksum
* @param size Size of data block in bytes
* @return checksum value (0 to 255)
*/
static grub_uint8_t
cros_ec_calc_checksum (const void *data, int size)
{
grub_uint8_t csum;
const grub_uint8_t *bytes = data;
int i;
for (i = csum = 0; i < size; i++)
csum += bytes[i];
return csum & 0xff;
}
enum
{
/* response, arglen */
CROS_EC_SPI_IN_HDR_SIZE = 2,
/* version, cmd, arglen */
CROS_EC_SPI_OUT_HDR_SIZE = 3
};
static grub_uint8_t busbuf[256];
#define MSG_BYTES ((int)sizeof (busbuf))
static int
ec_command (const struct grub_fdtbus_dev *dev, int cmd, int cmd_version,
const void *dout, int dout_len, void *din, int din_len)
{
const struct grub_fdtbus_dev *spi = dev->parent;
grub_uint8_t *bytes;
/* Header + data + checksum. */
grub_uint32_t out_bytes = CROS_EC_SPI_OUT_HDR_SIZE + dout_len + 1;
grub_uint32_t in_bytes = CROS_EC_SPI_IN_HDR_SIZE + din_len + 1;
/*
* Sanity-check I/O sizes given transaction overhead in internal
* buffers.
*/
if (out_bytes > MSG_BYTES)
{
grub_dprintf ("cros", "Cannot send %d bytes\n", dout_len);
return -1;
}
if (in_bytes > MSG_BYTES)
{
grub_dprintf ("cros", "Cannot receive %d bytes\n", din_len);
return -1;
}
/* Prepare the output. */
bytes = busbuf;
*bytes++ = EC_CMD_VERSION0 + cmd_version;
*bytes++ = cmd;
*bytes++ = dout_len;
grub_memcpy (bytes, dout, dout_len);
bytes += dout_len;
*bytes++ = cros_ec_calc_checksum (busbuf,
CROS_EC_SPI_OUT_HDR_SIZE + dout_len);
/* Depthcharge uses 200 us here but GRUB timer resolution is only 1ms,
decrease this when we increase timer resolution. */
while (grub_get_time_ms () - last_transfer < 1)
;
if (spi->driver->start (spi))
return -1;
/* Allow EC to ramp up clock after being awoken. */
/* Depthcharge only waits 100 us here but GRUB timer resolution is only 1ms,
decrease this when we increase timer resolution. */
grub_millisleep (1);
if (spi->driver->send (spi, busbuf, out_bytes))
{
stop_bus (spi);
return -1;
}
/* Wait until the EC is ready. */
if (wait_for_frame (spi))
{
stop_bus (spi);
return -1;
}
/* Read the response code and the data length. */
bytes = busbuf;
if (spi->driver->receive (spi, bytes, 2))
{
stop_bus (spi);
return -1;
}
grub_uint8_t result = *bytes++;
grub_uint8_t length = *bytes++;
/* Make sure there's enough room for the data. */
if (CROS_EC_SPI_IN_HDR_SIZE + length + 1 > MSG_BYTES)
{
grub_dprintf ("cros", "Received length %#02x too large\n", length);
stop_bus (spi);
return -1;
}
/* Read the data and the checksum, and finish up. */
if (spi->driver->receive (spi, bytes, length + 1))
{
stop_bus (spi);
return -1;
}
bytes += length;
int expected = *bytes++;
stop_bus (spi);
/* Check the integrity of the response. */
if (result != 0)
{
grub_dprintf ("cros", "Received bad result code %d\n", result);
return -result;
}
int csum = cros_ec_calc_checksum (busbuf,
CROS_EC_SPI_IN_HDR_SIZE + length);
if (csum != expected)
{
grub_dprintf ("cros", "Invalid checksum rx %#02x, calced %#02x\n",
expected, csum);
return -1;
}
/* If the caller wants the response, copy it out for them. */
if (length < din_len)
din_len = length;
if (din)
{
grub_memcpy (din, (grub_uint8_t *) busbuf + CROS_EC_SPI_IN_HDR_SIZE, din_len);
}
return din_len;
}
int
grub_cros_ec_scan_keyboard (const struct grub_fdtbus_dev *dev, struct grub_cros_ec_keyscan *scan)
{
if (ec_command (dev, EC_CMD_MKBP_STATE, 0, NULL, 0, scan,
sizeof (*scan)) < (int) sizeof (*scan))
return -1;
return 0;
}
int
grub_cros_ec_validate (const struct grub_fdtbus_dev *dev)
{
if (!grub_fdtbus_is_compatible("google,cros-ec-spi", dev))
return 0;
if (!dev->parent)
return 0;
if (!dev->parent->driver)
return 0;
if (!dev->parent->driver->send
|| !dev->parent->driver->receive)
return 0;
return 1;
}
|
