aboutsummaryrefslogtreecommitdiffstats
path: root/wirish/usb_serial.cpp
blob: 380f197c3309b6c9559a756f5b2e1823b7bbb4b8 (plain)
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
239
240
241
242
243
244
245
246
247
248
249
/******************************************************************************
 * The MIT License
 *
 * Copyright (c) 2010 Perry Hung.
 *
 * Permission is hereby granted, free of charge, to any person
 * obtaining a copy of this software and associated documentation
 * files (the "Software"), to deal in the Software without
 * restriction, including without limitation the rights to use, copy,
 * modify, merge, publish, distribute, sublicense, and/or sell copies
 * of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 *****************************************************************************/

/**
 * @brief USB virtual serial terminal
 */

#include <wirish/usb_serial.h>

#include <string.h>
#include <stdint.h>

#include <libmaple/nvic.h>
#include <libmaple/usb_cdcacm.h>
#include <libmaple/usb.h>

#include <wirish/wirish.h>

/*
 * Hooks used for bootloader reset signalling
 */

#if BOARD_HAVE_SERIALUSB
static void rxHook(unsigned, void*);
static void ifaceSetupHook(unsigned, void*);
#endif

/*
 * USBSerial interface
 */

#define USB_TIMEOUT 50

USBSerial::USBSerial(void) {
#if !BOARD_HAVE_SERIALUSB
    ASSERT(0);
#endif
}

void USBSerial::begin(void) {
#if BOARD_HAVE_SERIALUSB
    usb_cdcacm_enable(BOARD_USB_DISC_DEV, BOARD_USB_DISC_BIT);
    usb_cdcacm_set_hooks(USB_CDCACM_HOOK_RX, rxHook);
    usb_cdcacm_set_hooks(USB_CDCACM_HOOK_IFACE_SETUP, ifaceSetupHook);
#endif
}

void USBSerial::end(void) {
#if BOARD_HAVE_SERIALUSB
    usb_cdcacm_disable(BOARD_USB_DISC_DEV, BOARD_USB_DISC_BIT);
    usb_cdcacm_remove_hooks(USB_CDCACM_HOOK_RX | USB_CDCACM_HOOK_IFACE_SETUP);
#endif
}

void USBSerial::write(uint8 ch) {
    this->write(&ch, 1);
}

void USBSerial::write(const char *str) {
    this->write(str, strlen(str));
}

void USBSerial::write(const void *buf, uint32 len) {
    if (!this->isConnected() || !buf) {
        return;
    }

    uint32 txed = 0;
    uint32 old_txed = 0;
    uint32 start = millis();

    while (txed < len && (millis() - start < USB_TIMEOUT)) {
        txed += usb_cdcacm_tx((const uint8*)buf + txed, len - txed);
        if (old_txed != txed) {
            start = millis();
        }
        old_txed = txed;
    }
}

uint32 USBSerial::available(void) {
    return usb_cdcacm_data_available();
}

uint32 USBSerial::read(void *buf, uint32 len) {
    if (!buf) {
        return 0;
    }

    uint32 rxed = 0;
    while (rxed < len) {
        rxed += usb_cdcacm_rx((uint8*)buf + rxed, len - rxed);
    }

    return rxed;
}

/* Blocks forever until 1 byte is received */
uint8 USBSerial::read(void) {
    uint8 b;
    this->read(&b, 1);
    return b;
}

uint8 USBSerial::pending(void) {
    return usb_cdcacm_get_pending();
}

uint8 USBSerial::isConnected(void) {
    return usb_is_connected(USBLIB) && usb_is_configured(USBLIB);
}

uint8 USBSerial::getDTR(void) {
    return usb_cdcacm_get_dtr();
}

uint8 USBSerial::getRTS(void) {
    return usb_cdcacm_get_rts();
}

#if BOARD_HAVE_SERIALUSB
USBSerial SerialUSB;
#endif

/*
 * Bootloader hook implementations
 */

#if BOARD_HAVE_SERIALUSB

enum reset_state_t {
    DTR_UNSET,
    DTR_HIGH,
    DTR_NEGEDGE,
    DTR_LOW
};

static reset_state_t reset_state = DTR_UNSET;

static void ifaceSetupHook(unsigned hook, void *requestvp) {
    uint8 request = *(uint8*)requestvp;

    // Ignore requests we're not interested in.
    if (request != USB_CDCACM_SET_CONTROL_LINE_STATE) {
        return;
    }

    // We need to see a negative edge on DTR before we start looking
    // for the in-band magic reset byte sequence.
    uint8 dtr = usb_cdcacm_get_dtr();
    switch (reset_state) {
    case DTR_UNSET:
        reset_state = dtr ? DTR_HIGH : DTR_LOW;
        break;
    case DTR_HIGH:
        reset_state = dtr ? DTR_HIGH : DTR_NEGEDGE;
        break;
    case DTR_NEGEDGE:
        reset_state = dtr ? DTR_HIGH : DTR_LOW;
        break;
    case DTR_LOW:
        reset_state = dtr ? DTR_HIGH : DTR_LOW;
        break;
    }
}

#define RESET_DELAY 100000
static void wait_reset(void) {
  delay_us(RESET_DELAY);
  nvic_sys_reset();
}

#define STACK_TOP 0x20000800
#define EXC_RETURN 0xFFFFFFF9
#define DEFAULT_CPSR 0x61000000
static void rxHook(unsigned hook, void *ignored) {
    /* FIXME this is mad buggy; we need a new reset sequence. E.g. NAK
     * after each RX means you can't reset if any bytes are waiting. */
    if (reset_state == DTR_NEGEDGE) {
        reset_state = DTR_LOW;

        if (usb_cdcacm_data_available() >= 4) {
            // The magic reset sequence is "1EAF".
            static const uint8 magic[4] = {'1', 'E', 'A', 'F'};
            uint8 chkBuf[4];

            // Peek at the waiting bytes, looking for reset sequence,
            // bailing on mismatch.
            usb_cdcacm_peek(chkBuf, 4);
            for (unsigned i = 0; i < sizeof(magic); i++) {
                if (chkBuf[i] != magic[i]) {
                    return;
                }
            }

            // Got the magic sequence -> reset, presumably into the bootloader.
            // Return address is wait_reset, but we must set the thumb bit.
            uintptr_t target = (uintptr_t)wait_reset | 0x1;
            asm volatile("mov r0, %[stack_top]      \n\t" // Reset stack
                         "mov sp, r0                \n\t"
                         "mov r0, #1                \n\t"
                         "mov r1, %[target_addr]    \n\t"
                         "mov r2, %[cpsr]           \n\t"
                         "push {r2}                 \n\t" // Fake xPSR
                         "push {r1}                 \n\t" // PC target addr
                         "push {r0}                 \n\t" // Fake LR
                         "push {r0}                 \n\t" // Fake R12
                         "push {r0}                 \n\t" // Fake R3
                         "push {r0}                 \n\t" // Fake R2
                         "push {r0}                 \n\t" // Fake R1
                         "push {r0}                 \n\t" // Fake R0
                         "mov lr, %[exc_return]     \n\t"
                         "bx lr"
                         :
                         : [stack_top] "r" (STACK_TOP),
                           [target_addr] "r" (target),
                           [exc_return] "r" (EXC_RETURN),
                           [cpsr] "r" (DEFAULT_CPSR)
                         : "r0", "r1", "r2");
            /* Can't happen. */
            ASSERT_FAULT(0);
        }
    }
}

#endif  // BOARD_HAVE_SERIALUSB