2 * Project: AVR USB driver
3 * Author: Christian Starkjohann
4 * Creation Date: 2007-11-05
6 * Copyright: (c) 2007 by OBJECTIVE DEVELOPMENT Software GmbH
7 * License: GNU GPL v2 (see License.txt), GNU GPL v3 or proprietary (CommercialLicense.txt)
11 /* Do not link this file! Link usbdrvasm.S instead, which includes the
12 * appropriate implementation!
17 This file contains assembler code which is shared among the USB driver
18 implementations for different CPU cocks. Since the code must be inserted
19 in the middle of the module, it's split out into this file and #included.
21 Jump destinations called from outside:
22 sofError: Called when no start sequence was found.
23 se0: Called when a package has been successfully received.
24 overflow: Called when receive buffer overflows.
25 doReturn: Called after sending data.
27 Outside jump destinations used by this module:
28 waitForJ: Called to receive an already arriving packet.
34 The following macros must be defined before this file is included:
44 ldi x2, 1<<USB_INTR_PENDING_BIT
45 USB_STORE_PENDING(x2) ; clear any pending interrupts
48 rjmp storeTokenAndReturn
50 ;----------------------------------------------------------------------------
51 ; Processing of received packet (numbers in brackets are cycles after center of SE0)
52 ;----------------------------------------------------------------------------
53 ;This is the only non-error exit point for the software receiver loop
54 ;we don't check any CRCs here because there is no time left.
56 subi cnt, USB_BUFSIZE ;[5]
60 ldi x2, 1<<USB_INTR_PENDING_BIT ;[9]
61 USB_STORE_PENDING(x2) ;[10] clear pending intr and check flag later. SE0 should be over.
63 cpi token, USBPID_DATA0 ;[13]
65 cpi token, USBPID_DATA1 ;[15]
67 lds shift, usbDeviceAddr;[17]
68 ldd x2, y+1 ;[19] ADDR and 1 bit endpoint number
69 lsl x2 ;[21] shift out 1 bit endpoint number
71 rjmp ignorePacket ;[23]
72 /* only compute endpoint number in x3 if required later */
73 #if USB_CFG_HAVE_INTRIN_ENDPOINT || USB_CFG_IMPLEMENT_FN_WRITEOUT
74 ldd x3, y+2 ;[24] endpoint number + crc
75 rol x3 ;[26] shift in LSB of endpoint
77 cpi token, USBPID_IN ;[27]
79 cpi token, USBPID_SETUP ;[29]
80 breq handleSetupOrOut ;[30]
81 cpi token, USBPID_OUT ;[31]
82 brne ignorePacket ;[32] must be ack, nak or whatever
83 ; rjmp handleSetupOrOut ; fallthrough
85 ;Setup and Out are followed by a data packet two bit times (16 cycles) after
86 ;the end of SE0. The sync code allows up to 40 cycles delay from the start of
87 ;the sync pattern until the first bit is sampled. That's a total of 56 cycles.
88 handleSetupOrOut: ;[32]
89 #if USB_CFG_IMPLEMENT_FN_WRITEOUT /* if we have data for endpoint != 0, set usbCurrentTok to address */
91 breq storeTokenAndReturn ;[33]
92 mov token, x3 ;[34] indicate that this is endpoint x OUT
95 sts usbCurrentTok, token;[35]
97 POP_STANDARD ;[37] 12...16 cycles
98 USB_LOAD_PENDING(YL) ;[49]
99 sbrc YL, USB_INTR_PENDING_BIT;[50] check whether data is already arriving
100 rjmp waitForJ ;[51] save the pops and pushes -- a new interrupt is already pending
106 lds shift, usbCurrentTok;[18]
109 lds x2, usbRxLen ;[22]
111 brne sendNakAndReti ;[25]
112 ; 2006-03-11: The following two lines fix a problem where the device was not
113 ; recognized if usbPoll() was called less frequently than once every 4 ms.
114 cpi cnt, 4 ;[26] zero sized data packets are status phase only -- ignore and ack
115 brmi sendAckAndReti ;[27] keep rx buffer clean -- we must not NAK next SETUP
116 #if USB_CFG_CHECK_DATA_TOGGLING
117 sts usbCurrentDataToken, token ; store for checking by C code
119 sts usbRxLen, cnt ;[28] store received data, swap buffers
120 sts usbRxToken, shift ;[30]
121 lds x2, usbInputBufOffset;[32] swap buffers
122 ldi cnt, USB_BUFSIZE ;[34]
124 sts usbInputBufOffset, cnt;[36] buffers now swapped
125 rjmp sendAckAndReti ;[38] 40 + 17 = 57 until SOP
128 ;We don't send any data as long as the C code has not processed the current
129 ;input data and potentially updated the output data. That's more efficient
130 ;in terms of code size than clearing the tx buffers when a packet is received.
131 lds x1, usbRxLen ;[30]
132 cpi x1, 1 ;[32] negative values are flow control, 0 means "buffer free"
133 brge sendNakAndReti ;[33] unprocessed input packet?
134 ldi x1, USBPID_NAK ;[34] prepare value for usbTxLen
135 #if USB_CFG_HAVE_INTRIN_ENDPOINT
136 andi x3, 0xf ;[35] x3 contains endpoint
137 #if USB_CFG_SUPPRESS_INTR_CODE
138 brne sendNakAndReti ;[36]
143 lds cnt, usbTxLen ;[37]
144 sbrc cnt, 4 ;[39] all handshake tokens have bit 4 set
145 rjmp sendCntAndReti ;[40] 42 + 16 = 58 until SOP
146 sts usbTxLen, x1 ;[41] x1 == USBPID_NAK from above
147 ldi YL, lo8(usbTxBuf) ;[43]
148 ldi YH, hi8(usbTxBuf) ;[44]
149 rjmp usbSendAndReti ;[45] 57 + 12 = 59 until SOP
151 ; Comment about when to set usbTxLen to USBPID_NAK:
152 ; We should set it back when we receive the ACK from the host. This would
153 ; be simple to implement: One static variable which stores whether the last
154 ; tx was for endpoint 0 or 1 and a compare in the receiver to distinguish the
155 ; ACK. However, we set it back immediately when we send the package,
156 ; assuming that no error occurs and the host sends an ACK. We save one byte
157 ; RAM this way and avoid potential problems with endless retries. The rest of
158 ; the driver assumes error-free transfers anyway.
160 #if !USB_CFG_SUPPRESS_INTR_CODE && USB_CFG_HAVE_INTRIN_ENDPOINT /* placed here due to relative jump range */
162 #if USB_CFG_HAVE_INTRIN_ENDPOINT3
163 ; 2006-06-10 as suggested by O.Tamura: support second INTR IN / BULK IN endpoint
164 cpi x3, USB_CFG_EP3_NUMBER;[38]
167 lds cnt, usbTxLen1 ;[40]
168 sbrc cnt, 4 ;[42] all handshake tokens have bit 4 set
169 rjmp sendCntAndReti ;[43] 47 + 16 = 63 until SOP
170 sts usbTxLen1, x1 ;[44] x1 == USBPID_NAK from above
171 ldi YL, lo8(usbTxBuf1) ;[46]
172 ldi YH, hi8(usbTxBuf1) ;[47]
173 rjmp usbSendAndReti ;[48] 50 + 12 = 62 until SOP
175 #if USB_CFG_HAVE_INTRIN_ENDPOINT3
177 lds cnt, usbTxLen3 ;[41]
179 rjmp sendCntAndReti ;[44] 49 + 16 = 65 until SOP
180 sts usbTxLen3, x1 ;[45] x1 == USBPID_NAK from above
181 ldi YL, lo8(usbTxBuf3) ;[47]
182 ldi YH, hi8(usbTxBuf3) ;[48]
183 rjmp usbSendAndReti ;[49] 51 + 12 = 63 until SOP