1/* 16550 serial driver for gdbstub I/O
  2 *
  3 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
  4 * Written by David Howells (dhowells@redhat.com)
  5 *
  6 * This program is free software; you can redistribute it and/or
  7 * modify it under the terms of the GNU General Public Licence
  8 * as published by the Free Software Foundation; either version
  9 * 2 of the Licence, or (at your option) any later version.
 10 */
 11#include <linux/string.h>
 12#include <linux/kernel.h>
 13#include <linux/signal.h>
 14#include <linux/sched.h>
 15#include <linux/mm.h>
 16#include <linux/console.h>
 17#include <linux/init.h>
 18#include <linux/nmi.h>
 19
 20#include <asm/pgtable.h>
 21#include <asm/gdb-stub.h>
 22#include <asm/exceptions.h>
 23#include <asm/serial-regs.h>
 24#include <unit/serial.h>
 25#include <asm/smp.h>
 26
 27/*
 28 * initialise the GDB stub
 29 */
 30void gdbstub_io_init(void)
 31{
 32	u16 tmp;
 33
 34	/* set up the serial port */
 35	GDBPORT_SERIAL_LCR = UART_LCR_WLEN8; /* 1N8 */
 36	GDBPORT_SERIAL_FCR = (UART_FCR_ENABLE_FIFO | UART_FCR_CLEAR_RCVR |
 37			      UART_FCR_CLEAR_XMIT);
 38
 39	FLOWCTL_CLEAR(DTR);
 40	FLOWCTL_SET(RTS);
 41
 42	gdbstub_io_set_baud(115200);
 43
 44	/* we want to get serial receive interrupts */
 45	XIRQxICR(GDBPORT_SERIAL_IRQ) = 0;
 46	tmp = XIRQxICR(GDBPORT_SERIAL_IRQ);
 47
 48#if   CONFIG_GDBSTUB_IRQ_LEVEL == 0
 49	IVAR0 = EXCEP_IRQ_LEVEL0;
 50#elif CONFIG_GDBSTUB_IRQ_LEVEL == 1
 51	IVAR1 = EXCEP_IRQ_LEVEL1;
 52#elif CONFIG_GDBSTUB_IRQ_LEVEL == 2
 53	IVAR2 = EXCEP_IRQ_LEVEL2;
 54#elif CONFIG_GDBSTUB_IRQ_LEVEL == 3
 55	IVAR3 = EXCEP_IRQ_LEVEL3;
 56#elif CONFIG_GDBSTUB_IRQ_LEVEL == 4
 57	IVAR4 = EXCEP_IRQ_LEVEL4;
 58#elif CONFIG_GDBSTUB_IRQ_LEVEL == 5
 59	IVAR5 = EXCEP_IRQ_LEVEL5;
 60#else
 61#error "Unknown irq level for gdbstub."
 62#endif
 63
 64	set_intr_stub(NUM2EXCEP_IRQ_LEVEL(CONFIG_GDBSTUB_IRQ_LEVEL),
 65		gdbstub_io_rx_handler);
 66
 67	XIRQxICR(GDBPORT_SERIAL_IRQ) &= ~GxICR_REQUEST;
 68	XIRQxICR(GDBPORT_SERIAL_IRQ) =
 69		GxICR_ENABLE | NUM2GxICR_LEVEL(CONFIG_GDBSTUB_IRQ_LEVEL);
 70	tmp = XIRQxICR(GDBPORT_SERIAL_IRQ);
 71
 72	GDBPORT_SERIAL_IER = UART_IER_RDI | UART_IER_RLSI;
 73
 74	/* permit level 0 IRQs to take place */
 75	arch_local_change_intr_mask_level(
 76		NUM2EPSW_IM(CONFIG_GDBSTUB_IRQ_LEVEL + 1));
 77}
 78
 79/*
 80 * set up the GDB stub serial port baud rate timers
 81 */
 82void gdbstub_io_set_baud(unsigned baud)
 83{
 84	unsigned value;
 85	u8 lcr;
 86
 87	value = 18432000 / 16 / baud;
 88
 89	lcr = GDBPORT_SERIAL_LCR;
 90	GDBPORT_SERIAL_LCR |= UART_LCR_DLAB;
 91	GDBPORT_SERIAL_DLL = value & 0xff;
 92	GDBPORT_SERIAL_DLM = (value >> 8) & 0xff;
 93	GDBPORT_SERIAL_LCR = lcr;
 94}
 95
 96/*
 97 * wait for a character to come from the debugger
 98 */
 99int gdbstub_io_rx_char(unsigned char *_ch, int nonblock)
100{
101	unsigned ix;
102	u8 ch, st;
103#if defined(CONFIG_MN10300_WD_TIMER)
104	int cpu;
105#endif
106
107	*_ch = 0xff;
108
109	if (gdbstub_rx_unget) {
110		*_ch = gdbstub_rx_unget;
111		gdbstub_rx_unget = 0;
112		return 0;
113	}
114
115 try_again:
116	/* pull chars out of the buffer */
117	ix = gdbstub_rx_outp;
118	barrier();
119	if (ix == gdbstub_rx_inp) {
120		if (nonblock)
121			return -EAGAIN;
122#ifdef CONFIG_MN10300_WD_TIMER
123	for (cpu = 0; cpu < NR_CPUS; cpu++)
124		watchdog_alert_counter[cpu] = 0;
125#endif
126		goto try_again;
127	}
128
129	ch = gdbstub_rx_buffer[ix++];
130	st = gdbstub_rx_buffer[ix++];
131	barrier();
132	gdbstub_rx_outp = ix & 0x00000fff;
133
134	if (st & UART_LSR_BI) {
135		gdbstub_proto("### GDB Rx Break Detected ###\n");
136		return -EINTR;
137	} else if (st & (UART_LSR_FE | UART_LSR_OE | UART_LSR_PE)) {
138		gdbstub_proto("### GDB Rx Error (st=%02x) ###\n", st);
139		return -EIO;
140	} else {
141		gdbstub_proto("### GDB Rx %02x (st=%02x) ###\n", ch, st);
142		*_ch = ch & 0x7f;
143		return 0;
144	}
145}
146
147/*
148 * send a character to the debugger
149 */
150void gdbstub_io_tx_char(unsigned char ch)
151{
152	FLOWCTL_SET(DTR);
153	LSR_WAIT_FOR(THRE);
154	/* FLOWCTL_WAIT_FOR(CTS); */
155
156	if (ch == 0x0a) {
157		GDBPORT_SERIAL_TX = 0x0d;
158		LSR_WAIT_FOR(THRE);
159		/* FLOWCTL_WAIT_FOR(CTS); */
160	}
161	GDBPORT_SERIAL_TX = ch;
162
163	FLOWCTL_CLEAR(DTR);
164}
165
166/*
167 * send a character to the debugger
168 */
169void gdbstub_io_tx_flush(void)
170{
171	LSR_WAIT_FOR(TEMT);
172	LSR_WAIT_FOR(THRE);
173	FLOWCTL_CLEAR(DTR);
174}