1###############################################################################
2#
3# Virtual DMA driver for MN10300 serial ports
4#
5# Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
6# Written by David Howells (dhowells@redhat.com)
7#
8# This program is free software; you can redistribute it and/or
9# modify it under the terms of the GNU General Public Licence
10# as published by the Free Software Foundation; either version
11# 2 of the Licence, or (at your option) any later version.
12#
13###############################################################################
14#include <linux/sys.h>
15#include <linux/linkage.h>
16#include <asm/page.h>
17#include <asm/smp.h>
18#include <asm/cpu-regs.h>
19#include <asm/frame.inc>
20#include <asm/timer-regs.h>
21#include <proc/cache.h>
22#include <unit/timex.h>
23#include "mn10300-serial.h"
24
25#define	SCxCTR	0x00
26#define	SCxICR	0x04
27#define	SCxTXB	0x08
28#define	SCxRXB	0x09
29#define	SCxSTR	0x0c
30#define	SCxTIM	0x0d
31
32	.text
33
34###############################################################################
35#
36# serial port interrupt virtual DMA entry point
37# - intended to run at interrupt priority 1 (not affected by local_irq_disable)
38#
39###############################################################################
40	.balign	L1_CACHE_BYTES
41ENTRY(mn10300_serial_vdma_interrupt)
42#	or	EPSW_IE,psw			# permit overriding by
43						# debugging interrupts
44	movm	[d2,d3,a2,a3,exreg0],(sp)
45
46	movhu	(IAGR),a2			# see if which interrupt is
47						# pending
48	and	IAGR_GN,a2
49	add	a2,a2
50	add	mn10300_serial_int_tbl,a2
51
52	mov	(a2+),a3
53	mov	(__iobase,a3),e2
54	mov	(a2),a2
55	jmp	(a2)
56
57###############################################################################
58#
59# serial port receive interrupt virtual DMA entry point
60# - intended to run at interrupt priority 1 (not affected by local_irq_disable)
61# - stores data/status byte pairs in the ring buffer
62# - induces a scheduler tick timer interrupt when done, which we then subvert
63# on entry:
64#	A3	struct mn10300_serial_port *
65#	E2	I/O port base
66#
67###############################################################################
68ENTRY(mn10300_serial_vdma_rx_handler)
69	mov	(__rx_icr,a3),e3
70	mov	GxICR_DETECT,d2
71	movbu	d2,(e3)				# ACK the interrupt
72	movhu	(e3),d2				# flush
73
74	mov	(__rx_inp,a3),d3
75	mov	d3,a2
76	add	2,d3
77	and	MNSC_BUFFER_SIZE-1,d3
78	mov	(__rx_outp,a3),d2
79	cmp	d3,d2
80	beq	mnsc_vdma_rx_overflow
81
82	mov	(__rx_buffer,a3),d2
83	add	d2,a2
84	movhu	(SCxSTR,e2),d2
85	movbu	d2,(1,a2)
86	movbu	(SCxRXB,e2),d2
87	movbu	d2,(a2)
88	mov	d3,(__rx_inp,a3)
89	bset	MNSCx_RX_AVAIL,(__intr_flags,a3)
90
91mnsc_vdma_rx_done:
92	mov	(__tm_icr,a3),a2
93	mov	GxICR_LEVEL_6|GxICR_ENABLE|GxICR_REQUEST|GxICR_DETECT,d2
94	movhu	d2,(a2)				# request a slow interrupt
95	movhu	(a2),d2				# flush
96
97	movm	(sp),[d2,d3,a2,a3,exreg0]
98	rti
99
100mnsc_vdma_rx_overflow:
101	bset	MNSCx_RX_OVERF,(__intr_flags,a3)
102	bra	mnsc_vdma_rx_done
103
104###############################################################################
105#
106# serial port transmit interrupt virtual DMA entry point
107# - intended to run at interrupt priority 1 (not affected by local_irq_disable)
108# - retrieves data bytes from the ring buffer and passes them to the serial port
109# - induces a scheduler tick timer interrupt when done, which we then subvert
110#	A3	struct mn10300_serial_port *
111#	E2	I/O port base
112#
113###############################################################################
114	.balign	L1_CACHE_BYTES
115ENTRY(mn10300_serial_vdma_tx_handler)
116	mov	(__tx_icr,a3),e3
117	mov	GxICR_DETECT,d2
118	movbu	d2,(e3)			# ACK the interrupt
119	movhu	(e3),d2			# flush
120
121	btst	0x01,(__tx_break,a3)	# handle transmit break request
122	bne	mnsc_vdma_tx_break
123
124	movbu	(SCxSTR,e2),d2		# don't try and transmit a char if the
125					# buffer is not empty
126	btst	SC01STR_TBF,d2		# (may have tried to jumpstart)
127	bne	mnsc_vdma_tx_noint
128
129	movbu	(__tx_xchar,a3),d2	# handle hi-pri XON/XOFF
130	or	d2,d2
131	bne	mnsc_vdma_tx_xchar
132
133	mov	(__uart_state,a3),a2	# see if the TTY Tx queue has anything in it
134	mov	(__xmit_tail,a2),d3
135	mov	(__xmit_head,a2),d2
136	cmp	d3,d2
137	beq	mnsc_vdma_tx_empty
138
139	mov	(__xmit_buffer,a2),d2	# get a char from the buffer and
140					# transmit it
141	movbu	(d3,d2),d2
142	movbu	d2,(SCxTXB,e2)		# Tx
143
144	inc	d3			# advance the buffer pointer
145	and	__UART_XMIT_SIZE-1,d3
146	mov	(__xmit_head,a2),d2
147	mov	d3,(__xmit_tail,a2)
148
149	sub	d3,d2			# see if we've written everything
150	beq	mnsc_vdma_tx_empty
151
152	and	__UART_XMIT_SIZE-1,d2	# see if we just made a hole
153	cmp	__UART_XMIT_SIZE-2,d2
154	beq	mnsc_vdma_tx_made_hole
155
156mnsc_vdma_tx_done:
157	mov	(__tm_icr,a3),a2
158	mov	GxICR_LEVEL_6|GxICR_ENABLE|GxICR_REQUEST|GxICR_DETECT,d2
159	movhu	d2,(a2)			# request a slow interrupt
160	movhu	(a2),d2			# flush
161
162mnsc_vdma_tx_noint:
163	movm	(sp),[d2,d3,a2,a3,exreg0]
164	rti
165
166mnsc_vdma_tx_empty:
167	mov	+(NUM2GxICR_LEVEL(CONFIG_MN10300_SERIAL_IRQ_LEVEL)|GxICR_DETECT),d2
168	movhu	d2,(e3)			# disable the interrupt
169	movhu	(e3),d2			# flush
170
171	bset	MNSCx_TX_EMPTY,(__intr_flags,a3)
172	bra	mnsc_vdma_tx_done
173
174mnsc_vdma_tx_break:
175	movhu	(SCxCTR,e2),d2		# turn on break mode
176	or	SC01CTR_BKE,d2
177	movhu	d2,(SCxCTR,e2)
178	mov	+(NUM2GxICR_LEVEL(CONFIG_MN10300_SERIAL_IRQ_LEVEL)|GxICR_DETECT),d2
179	movhu	d2,(e3)			# disable transmit interrupts on this
180					# channel
181	movhu	(e3),d2			# flush
182	bra	mnsc_vdma_tx_noint
183
184mnsc_vdma_tx_xchar:
185	bclr	0xff,(__tx_xchar,a3)
186	movbu	d2,(SCxTXB,e2)
187	bra	mnsc_vdma_tx_done
188
189mnsc_vdma_tx_made_hole:
190	bset	MNSCx_TX_SPACE,(__intr_flags,a3)
191	bra	mnsc_vdma_tx_done
192