--- /dev/null
+/*
+ * Microcontroller message bus
+ * uc-side slave implementation for Atmel AVR8
+ *
+ * The gcc compiler always treats multi-byte variables as litte-endian.
+ * So no explicit endianness conversions are done on the message header,
+ * footer and status data structures.
+ *
+ * This hotpath-assembly implementation is about twice as fast
+ * as the C implementation.
+ *
+ * Copyright (C) 2009 Michael Buesch <mb@bu3sch.de>
+ *
+ * This program 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 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program 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.
+ */
+
+#include "ucmb.h"
+#include "util.h"
+#include "uart.h"
+
+#include <stdint.h>
+#include <avr/io.h>
+#include <avr/interrupt.h>
+#include <avr/pgmspace.h>
+#include <avr/wdt.h>
+
+
+#ifndef __GNUC__
+# error "Need the GNU C compiler"
+#endif
+
+#undef __naked
+#define __naked __attribute__((__naked__))
+#undef __used
+#define __used __attribute__((__used__))
+
+
+struct ucmb_message_hdr {
+ uint16_t magic; /* UCMB_MAGIC */
+ uint16_t len; /* Payload length (excluding header and footer) */
+} __attribute__((packed));
+
+struct ucmb_message_footer {
+ uint16_t crc; /* CRC of the header + payload. */
+} __attribute__((packed));
+
+struct ucmb_status {
+ uint16_t magic; /* UCMB_MAGIC */
+ uint16_t code; /* enum ucmb_status_code */
+} __attribute__((packed));
+
+#define UCMB_MAGIC 0x1337
+
+enum ucmb_status_code {
+ UCMB_STAT_OK = 0,
+ UCMB_STAT_EPROTO, /* Protocol format error */
+ UCMB_STAT_ENOMEM, /* Out of memory */
+ UCMB_STAT_E2BIG, /* Message too big */
+ UCMB_STAT_ECRC, /* CRC error */
+};
+
+
+static uint8_t ucmb_buf[sizeof(struct ucmb_message_hdr) +
+ UCMB_MAX_MSG_LEN +
+ sizeof(struct ucmb_message_footer)] __used;
+static uint16_t ucmb_buf_ptr __used;
+static struct ucmb_status status_buf __used;
+static uint16_t ucmb_send_message_len __used;
+
+/* The current IRQ handler */
+static void (*ucmb_interrupt_handler)(void) __used;
+
+
+/* Polynomial: x^16 + x^15 + x^2 + 1 */
+static const prog_uint16_t crc16_table[256] = {
+ 0x0000, 0xC0C1, 0xC181, 0x0140, 0xC301, 0x03C0, 0x0280, 0xC241,
+ 0xC601, 0x06C0, 0x0780, 0xC741, 0x0500, 0xC5C1, 0xC481, 0x0440,
+ 0xCC01, 0x0CC0, 0x0D80, 0xCD41, 0x0F00, 0xCFC1, 0xCE81, 0x0E40,
+ 0x0A00, 0xCAC1, 0xCB81, 0x0B40, 0xC901, 0x09C0, 0x0880, 0xC841,
+ 0xD801, 0x18C0, 0x1980, 0xD941, 0x1B00, 0xDBC1, 0xDA81, 0x1A40,
+ 0x1E00, 0xDEC1, 0xDF81, 0x1F40, 0xDD01, 0x1DC0, 0x1C80, 0xDC41,
+ 0x1400, 0xD4C1, 0xD581, 0x1540, 0xD701, 0x17C0, 0x1680, 0xD641,
+ 0xD201, 0x12C0, 0x1380, 0xD341, 0x1100, 0xD1C1, 0xD081, 0x1040,
+ 0xF001, 0x30C0, 0x3180, 0xF141, 0x3300, 0xF3C1, 0xF281, 0x3240,
+ 0x3600, 0xF6C1, 0xF781, 0x3740, 0xF501, 0x35C0, 0x3480, 0xF441,
+ 0x3C00, 0xFCC1, 0xFD81, 0x3D40, 0xFF01, 0x3FC0, 0x3E80, 0xFE41,
+ 0xFA01, 0x3AC0, 0x3B80, 0xFB41, 0x3900, 0xF9C1, 0xF881, 0x3840,
+ 0x2800, 0xE8C1, 0xE981, 0x2940, 0xEB01, 0x2BC0, 0x2A80, 0xEA41,
+ 0xEE01, 0x2EC0, 0x2F80, 0xEF41, 0x2D00, 0xEDC1, 0xEC81, 0x2C40,
+ 0xE401, 0x24C0, 0x2580, 0xE541, 0x2700, 0xE7C1, 0xE681, 0x2640,
+ 0x2200, 0xE2C1, 0xE381, 0x2340, 0xE101, 0x21C0, 0x2080, 0xE041,
+ 0xA001, 0x60C0, 0x6180, 0xA141, 0x6300, 0xA3C1, 0xA281, 0x6240,
+ 0x6600, 0xA6C1, 0xA781, 0x6740, 0xA501, 0x65C0, 0x6480, 0xA441,
+ 0x6C00, 0xACC1, 0xAD81, 0x6D40, 0xAF01, 0x6FC0, 0x6E80, 0xAE41,
+ 0xAA01, 0x6AC0, 0x6B80, 0xAB41, 0x6900, 0xA9C1, 0xA881, 0x6840,
+ 0x7800, 0xB8C1, 0xB981, 0x7940, 0xBB01, 0x7BC0, 0x7A80, 0xBA41,
+ 0xBE01, 0x7EC0, 0x7F80, 0xBF41, 0x7D00, 0xBDC1, 0xBC81, 0x7C40,
+ 0xB401, 0x74C0, 0x7580, 0xB541, 0x7700, 0xB7C1, 0xB681, 0x7640,
+ 0x7200, 0xB2C1, 0xB381, 0x7340, 0xB101, 0x71C0, 0x7080, 0xB041,
+ 0x5000, 0x90C1, 0x9181, 0x5140, 0x9301, 0x53C0, 0x5280, 0x9241,
+ 0x9601, 0x56C0, 0x5780, 0x9741, 0x5500, 0x95C1, 0x9481, 0x5440,
+ 0x9C01, 0x5CC0, 0x5D80, 0x9D41, 0x5F00, 0x9FC1, 0x9E81, 0x5E40,
+ 0x5A00, 0x9AC1, 0x9B81, 0x5B40, 0x9901, 0x59C0, 0x5880, 0x9841,
+ 0x8801, 0x48C0, 0x4980, 0x8941, 0x4B00, 0x8BC1, 0x8A81, 0x4A40,
+ 0x4E00, 0x8EC1, 0x8F81, 0x4F40, 0x8D01, 0x4DC0, 0x4C80, 0x8C41,
+ 0x4400, 0x84C1, 0x8581, 0x4540, 0x8701, 0x47C0, 0x4680, 0x8641,
+ 0x8201, 0x42C0, 0x4380, 0x8341, 0x4100, 0x81C1, 0x8081, 0x4040
+};
+
+static inline uint16_t crc16_block_update(uint16_t crc, const void *_data, uint16_t size)
+{
+ const uint8_t *data = _data;
+ uint8_t offset;
+
+ while (size--) {
+ wdt_reset();
+ offset = crc ^ *data;
+ crc = (crc >> 8) ^ pgm_read_word(&crc16_table[offset]);
+ data++;
+ }
+
+ return crc;
+}
+
+static inline uint16_t ucmb_calc_msg_buffer_crc(void)
+{
+ const struct ucmb_message_hdr *hdr;
+ uint16_t crc = 0xFFFF;
+
+ hdr = (const struct ucmb_message_hdr *)ucmb_buf;
+ crc = crc16_block_update(crc, ucmb_buf,
+ sizeof(struct ucmb_message_hdr) + hdr->len);
+ crc ^= 0xFFFF;
+
+ return crc;
+}
+
+/* The generic interrupt handler.
+ * This just branches to the state specific handler.
+ */
+ISR(SPI_STC_vect) __naked;
+ISR(SPI_STC_vect)
+{
+ __asm__ __volatile__(
+" ; UCMB generic interrupt handler \n"
+" push __tmp_reg__ \n"
+" in __tmp_reg__, __SREG__ \n"
+" push r30 \n"
+" push r31 \n"
+" lds r30, ucmb_interrupt_handler + 0 \n"
+" lds r31, ucmb_interrupt_handler + 1 \n"
+" ijmp ; Jump to the real handler \n"
+ );
+}
+#define UCMB_IRQ_EPILOGUE \
+" ; UCMB interrupt epilogue (start) \n"\
+" pop r31 \n"\
+" pop r30 \n"\
+" out __SREG__, __tmp_reg__ \n"\
+" pop __tmp_reg__ \n"\
+" reti \n"\
+" ; UCMB interrupt epilogue (end) \n"
+
+static void __naked __used ucmb_handler_LISTEN(void)
+{
+ __asm__ __volatile__(
+" push r16 \n"
+" push r17 \n"
+" push r18 \n"
+" lds r16, ucmb_buf_ptr + 0 \n"
+" lds r17, ucmb_buf_ptr + 1 \n"
+" ldi r18, hi8(%[sizeof_buf]) \n"
+" cpi r16, lo8(%[sizeof_buf]) \n"
+" cpc r17, r18 \n"
+" in r18, %[_SPDR] \n"
+" brsh 1f ; overflow \n"
+" ; Store SPDR in the buffer \n"
+" movw r30, r16 \n"
+" subi r30, lo8(-(ucmb_buf)) \n"
+" sbci r31, hi8(-(ucmb_buf)) \n"
+" st Z, r18 \n"
+"1: \n"
+" ; Increment the buffer pointer \n"
+" subi r16, lo8(-1) \n"
+" sbci r17, hi8(-1) \n"
+" sts ucmb_buf_ptr + 0, r16 \n"
+" sts ucmb_buf_ptr + 1, r17 \n"
+" cpi r17, 0 \n"
+" brne 1f \n"
+" cpi r16, %[sizeof_msg_hdr] \n"
+" breq hdr_sanity_check ; buf_ptr == hdrlen \n"
+" brlo st_listen_out ; buf_ptr < hdrlen \n"
+"1: \n"
+" ; Get payload length from header \n"
+" lds r30, (ucmb_buf + %[offsetof_hdr_len] + 0) \n"
+" lds r31, (ucmb_buf + %[offsetof_hdr_len] + 1) \n"
+" ; Add header and footer length to get full length \n"
+" subi r30, lo8(-(%[sizeof_msg_hdr] + %[sizeof_msg_footer])) \n"
+" sbci r31, hi8(-(%[sizeof_msg_hdr] + %[sizeof_msg_footer])) \n"
+" ; Check if we have the full packet \n"
+" cp r30, r16 \n"
+" cpc r31, r17 \n"
+" breq st_listen_have_full_packet \n"
+"st_listen_out: \n"
+" pop r18 \n"
+" pop r17 \n"
+" pop r16 \n"
+UCMB_IRQ_EPILOGUE /* reti */
+" \n"
+"hdr_sanity_check: \n"
+" lds r30, (ucmb_buf + %[offsetof_hdr_magic] + 0) \n"
+" lds r31, (ucmb_buf + %[offsetof_hdr_magic] + 1) \n"
+" ldi r18, hi8(%[_UCMB_MAGIC]) \n"
+" cpi r30, lo8(%[_UCMB_MAGIC]) \n"
+" cpc r31, r18 \n"
+" brne invalid_hdr_magic \n"
+" lds r30, (ucmb_buf + %[offsetof_hdr_len] + 0) \n"
+" lds r31, (ucmb_buf + %[offsetof_hdr_len] + 1) \n"
+" ldi r18, hi8(0x8001) \n"
+" cpi r30, lo8(0x8001) \n"
+" cpc r31, r18 \n"
+" brsh bogus_payload_len \n"
+" rjmp st_listen_out \n"
+" \n"
+"invalid_hdr_magic: \n"
+" ; Invalid magic number in the packet header. Reset. \n"
+"bogus_payload_len: \n"
+" ; Bogus payload length in packet header. Reset. \n"
+" clr r18 \n"
+" sts ucmb_buf_ptr + 0, r18 \n"
+" sts ucmb_buf_ptr + 1, r18 \n"
+" rjmp st_listen_out \n"
+" \n"
+"st_listen_have_full_packet: \n"
+" ; We have the full packet. Any SPI transfer is stopped \n"
+" ; while we are processing the packet, so this \n"
+" ; is a slowpath. Branch to a C function. \n"
+" clr __zero_reg__ \n"
+" push r18 \n"
+" push r19 \n"
+" push r20 \n"
+" push r21 \n"
+" push r22 \n"
+" push r23 \n"
+" push r24 \n"
+" push r25 \n"
+" push r26 \n"
+" push r27 \n"
+" push r30 \n"
+" push r31 \n"
+" push __tmp_reg__ \n"
+" rcall ucmb_received_packet \n"
+" pop __tmp_reg__ \n"
+" pop r31 \n"
+" pop r30 \n"
+" pop r27 \n"
+" pop r26 \n"
+" pop r25 \n"
+" pop r24 \n"
+" pop r23 \n"
+" pop r22 \n"
+" pop r21 \n"
+" pop r20 \n"
+" pop r19 \n"
+" pop r18 \n"
+" rjmp st_listen_out \n"
+ : /* none */
+ : [sizeof_buf] "i" (sizeof(ucmb_buf))
+ , [sizeof_msg_hdr] "M" (sizeof(struct ucmb_message_hdr))
+ , [sizeof_msg_footer] "M" (sizeof(struct ucmb_message_footer))
+ , [offsetof_hdr_magic] "M" (offsetof(struct ucmb_message_hdr, magic))
+ , [offsetof_hdr_len] "M" (offsetof(struct ucmb_message_hdr, len))
+ , [_SPDR] "M" (_SFR_IO_ADDR(SPDR))
+ , [_UCMB_MAGIC] "i" (UCMB_MAGIC)
+ : "memory"
+ );
+}
+
+static void __naked __used ucmb_handler_SENDSTATUS(void)
+{
+ __asm__ __volatile__(
+" push r16 \n"
+/*" push r17 \n" */
+" push r18 \n"
+" lds r16, ucmb_buf_ptr + 0 \n"
+" cpi r16, %[sizeof_ucmb_status] \n"
+" brsh 1f ; This is the trailing byte \n"
+" ; Write the next byte from status_buf to SPDR \n"
+" mov r30, r16 \n"
+" clr r31 \n"
+" subi r30, lo8(-(status_buf)) \n"
+" sbci r31, hi8(-(status_buf)) \n"
+" ld r18, Z \n"
+" out %[_SPDR], r18 \n"
+"1: \n"
+" subi r16, lo8(-1) \n"
+" sts ucmb_buf_ptr + 0, r16 \n"
+" cpi r16, (%[sizeof_ucmb_status] + 1) \n"
+" brne st_sendstatus_out \n"
+" ; Finished. Sent all status_buf bytes + trailing byte. \n"
+" clr r18 \n"
+" sts ucmb_buf_ptr + 0, r18 \n"
+" ; Switch back to listening state... \n"
+" ldi r18, lo8(gs(ucmb_handler_LISTEN)) \n"
+" sts ucmb_interrupt_handler + 0, r18 \n"
+" ldi r18, hi8(gs(ucmb_handler_LISTEN)) \n"
+" sts ucmb_interrupt_handler + 1, r18 \n"
+" ; ...if we have no pending transmission \n"
+" lds r30, ucmb_send_message_len + 0 \n"
+" lds r31, ucmb_send_message_len + 1 \n"
+" clr r18 \n"
+" cpi r30, 0 \n"
+" cpc r31, r18 \n"
+" breq st_sendstatus_out \n"
+" ; Switch status to SENDMESSAGE and send the first byte. \n"
+" ldi r18, lo8(gs(ucmb_handler_SENDMESSAGE)) \n"
+" sts ucmb_interrupt_handler + 0, r18 \n"
+" ldi r18, hi8(gs(ucmb_handler_SENDMESSAGE)) \n"
+" sts ucmb_interrupt_handler + 1, r18 \n"
+" ; Send the first byte \n"
+" lds r18, ucmb_buf + 0 \n"
+" out %[_SPDR], r18 \n"
+" ldi r18, 1 \n"
+" sts ucmb_buf_ptr + 0, r18 \n"
+"st_sendstatus_out: \n"
+" pop r18 \n"
+/*" pop r17 \n"*/
+" pop r16 \n"
+UCMB_IRQ_EPILOGUE /* reti */
+ : /* none */
+ : [sizeof_ucmb_status] "M" (sizeof(struct ucmb_status))
+ , [_SPDR] "M" (_SFR_IO_ADDR(SPDR))
+ : "memory"
+ );
+}
+
+static void __naked __used ucmb_handler_SENDMESSAGE(void)
+{
+ __asm__ __volatile__(
+" push r16 \n"
+" push r17 \n"
+" push r18 \n"
+" lds r16, ucmb_buf_ptr + 0 \n"
+" lds r17, ucmb_buf_ptr + 1 \n"
+" lds r30, ucmb_send_message_len + 0 \n"
+" lds r31, ucmb_send_message_len + 1 \n"
+" cp r16, r30 \n"
+" cpc r17, r31 \n"
+" brsh 1f ; This is the trailing byte \n"
+" movw r30, r16 \n"
+" subi r30, lo8(-(ucmb_buf)) \n"
+" sbci r31, hi8(-(ucmb_buf)) \n"
+" ld r18, Z \n"
+" out %[_SPDR], r18 \n"
+"1: \n"
+" subi r16, lo8(-1) \n"
+" sbci r17, hi8(-1) \n"
+" sts ucmb_buf_ptr + 0, r16 \n"
+" sts ucmb_buf_ptr + 1, r17 \n"
+" lds r30, ucmb_send_message_len + 0 \n"
+" lds r31, ucmb_send_message_len + 1 \n"
+" subi r30, lo8(-1) \n"
+" sbci r31, hi8(-1) \n"
+" cp r16, r30 \n"
+" cpc r17, r31 \n"
+" brne st_sendmessage_out \n"
+" ; Message + trailing byte processed. Retrieve status. \n"
+" clr r18 \n"
+" sts ucmb_buf_ptr + 0, r18 \n"
+" sts ucmb_buf_ptr + 1, r18 \n"
+" ldi r18, lo8(gs(ucmb_handler_RETRSTATUS)) \n"
+" sts ucmb_interrupt_handler + 0, r18 \n"
+" ldi r18, hi8(gs(ucmb_handler_RETRSTATUS)) \n"
+" sts ucmb_interrupt_handler + 1, r18 \n"
+"st_sendmessage_out: \n"
+" pop r18 \n"
+" pop r17 \n"
+" pop r16 \n"
+UCMB_IRQ_EPILOGUE /* reti */
+ : /* none */
+ : [_SPDR] "M" (_SFR_IO_ADDR(SPDR))
+ : "memory"
+ );
+}
+
+static void __naked __used ucmb_handler_RETRSTATUS(void)
+{
+ __asm__ __volatile__(
+" push r16 \n"
+/*" push r17 \n"*/
+" push r18 \n"
+" in r18, %[_SPDR] \n"
+" lds r16, ucmb_buf_ptr + 0 \n"
+" mov r30, r16 \n"
+" clr r31 \n"
+" subi r30, lo8(-(status_buf)) \n"
+" sbci r31, hi8(-(status_buf)) \n"
+" st Z, r18 \n"
+" subi r16, -1 \n"
+" sts ucmb_buf_ptr + 0, r16 \n"
+" cpi r16, %[sizeof_ucmb_status] \n"
+" brne st_retrstatus_out \n"
+" ; Completely received the status \n"
+" clr r16 \n"
+" sts ucmb_buf_ptr + 0, r16 \n"
+" ; Switch back to listening state... \n"
+" ldi r18, lo8(gs(ucmb_handler_LISTEN)) \n"
+" sts ucmb_interrupt_handler + 0, r18 \n"
+" ldi r18, hi8(gs(ucmb_handler_LISTEN)) \n"
+" sts ucmb_interrupt_handler + 1, r18 \n"
+" ; Check status-report magic value \n"
+" lds r30, (status_buf + %[offsetof_status_magic] + 0) \n"
+" lds r31, (status_buf + %[offsetof_status_magic] + 1) \n"
+" ldi r18, hi8(%[_UCMB_MAGIC]) \n"
+" cpi r30, lo8(%[_UCMB_MAGIC]) \n"
+" cpc r31, r18 \n"
+" brne invalid_status_magic \n"
+" ; Check status-report error code \n"
+" lds r30, (status_buf + %[offsetof_status_code] + 0) \n"
+" lds r31, (status_buf + %[offsetof_status_code] + 1) \n"
+" ldi r18, hi8(%[_UCMB_STAT_OK]) \n"
+" cpi r30, lo8(%[_UCMB_STAT_OK]) \n"
+" cpc r31, r18 \n"
+" brne faulty_status_code \n"
+"st_retrstatus_out: \n"
+" pop r18 \n"
+/*" pop r17 \n"*/
+" pop r16 \n"
+UCMB_IRQ_EPILOGUE /* reti */
+" \n"
+"invalid_status_magic: \n"
+"faulty_status_code: \n"
+" ; Branch to the C error handler \n"
+" clr __zero_reg__ \n"
+" push r18 \n"
+" push r19 \n"
+" push r20 \n"
+" push r21 \n"
+" push r22 \n"
+" push r23 \n"
+" push r24 \n"
+" push r25 \n"
+" push r26 \n"
+" push r27 \n"
+" push r30 \n"
+" push r31 \n"
+" push __tmp_reg__ \n"
+" rcall ucmb_received_faulty_status \n"
+" pop __tmp_reg__ \n"
+" pop r31 \n"
+" pop r30 \n"
+" pop r27 \n"
+" pop r26 \n"
+" pop r25 \n"
+" pop r24 \n"
+" pop r23 \n"
+" pop r22 \n"
+" pop r21 \n"
+" pop r20 \n"
+" pop r19 \n"
+" pop r18 \n"
+" rjmp st_retrstatus_out \n"
+ : /* none */
+ : [sizeof_ucmb_status] "M" (sizeof(struct ucmb_status))
+ , [offsetof_status_magic] "M" (offsetof(struct ucmb_status, magic))
+ , [offsetof_status_code] "M" (offsetof(struct ucmb_status, code))
+ , [_SPDR] "M" (_SFR_IO_ADDR(SPDR))
+ , [_UCMB_MAGIC] "i" (UCMB_MAGIC)
+ , [_UCMB_STAT_OK] "i" (UCMB_STAT_OK)
+ : "memory"
+ );
+}
+
+/* We received a full packet. This is called from assembly code. */
+static void __used ucmb_received_packet(void)
+{
+ struct ucmb_message_hdr *hdr;
+ struct ucmb_message_footer *footer;
+ uint16_t payload_len;
+
+ hdr = (struct ucmb_message_hdr *)ucmb_buf;
+ payload_len = hdr->len;
+
+ status_buf.magic = UCMB_MAGIC;
+ status_buf.code = UCMB_STAT_OK;
+ if (unlikely(ucmb_buf_ptr > sizeof(ucmb_buf))) {
+ /* Message is way too big and was truncated. */
+ status_buf.code = UCMB_STAT_E2BIG;
+ } else {
+ footer = (struct ucmb_message_footer *)(
+ ucmb_buf + sizeof(struct ucmb_message_hdr) +
+ payload_len);
+ if (ucmb_calc_msg_buffer_crc() != footer->crc)
+ status_buf.code = UCMB_STAT_ECRC;
+ }
+ ucmb_interrupt_handler = ucmb_handler_SENDSTATUS;
+ ucmb_buf_ptr = 0;
+ /* Send the first byte */
+ SPDR = ((uint8_t *)&status_buf)[ucmb_buf_ptr];
+ ucmb_buf_ptr++;
+
+ if (unlikely(status_buf.code != UCMB_STAT_OK))
+ return; /* Corrupt message. Don't pass it to user code. */
+
+ ucmb_send_message_len = ucmb_rx_message(
+ ucmb_buf + sizeof(struct ucmb_message_hdr),
+ payload_len);
+ if (ucmb_send_message_len) {
+ footer = (struct ucmb_message_footer *)(
+ ucmb_buf + sizeof(struct ucmb_message_hdr) +
+ ucmb_send_message_len);
+
+ hdr->magic = UCMB_MAGIC;
+ hdr->len = ucmb_send_message_len;
+ footer->crc = ucmb_calc_msg_buffer_crc();
+
+ ucmb_send_message_len += sizeof(struct ucmb_message_hdr) +
+ sizeof(struct ucmb_message_footer);
+ }
+}
+
+/* We received a status report with an error condition.
+ * This is called from assembly code. */
+static void __used ucmb_received_faulty_status(void)
+{
+ /* The master sent us a status report with an error code.
+ * Something's wrong with us. Print a status message and
+ * get caught by the watchdog, yummy.
+ */
+
+ cli();
+ wdt_disable();
+ uart_logmsg("UCMB: Received faulty status report. Triggering reset.");
+ wdt_enable(WDTO_15MS);
+ while (1) {
+ /* "It's Coming Right For Us!" */
+ }
+}
+
+void ucmb_init(void)
+{
+ ucmb_interrupt_handler = ucmb_handler_LISTEN;
+
+ /* SPI slave mode 0 with IRQ enabled. */
+ DDRB |= (1 << 6/*MISO*/);
+ DDRB &= ~((1 << 7/*SCK*/) | (1 << 5/*MOSI*/) | (1 << 4/*SS*/));
+ SPCR = (1 << SPE) | (1 << SPIE) /*| (1 << CPOL) | (1 << CPHA)*/;
+ (void)SPSR; /* clear state */
+ (void)SPDR; /* clear state */
+}
projects / openwrt / svn-archive / archive.git / commitdiff