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/system.h>
 22#include <asm/gdb-stub.h>
 23#include <asm/exceptions.h>
 24#include <asm/serial-regs.h>
 25#include <unit/serial.h>
 26#include <asm/smp.h>
 27
 28/*
 29 * initialise the GDB stub
 30 */
 31void gdbstub_io_init(void)
 32{
 33	u16 tmp;
 34
 35	/* set up the serial port */
 36	GDBPORT_SERIAL_LCR = UART_LCR_WLEN8; /* 1N8 */
 37	GDBPORT_SERIAL_FCR = (UART_FCR_ENABLE_FIFO | UART_FCR_CLEAR_RCVR |
 38			      UART_FCR_CLEAR_XMIT);
 39
 40	FLOWCTL_CLEAR(DTR);
 41	FLOWCTL_SET(RTS);
 42
 43	gdbstub_io_set_baud(115200);
 44
 45	/* we want to get serial receive interrupts */
 46	XIRQxICR(GDBPORT_SERIAL_IRQ) = 0;
 47	tmp = XIRQxICR(GDBPORT_SERIAL_IRQ);
 48
 49#if   CONFIG_GDBSTUB_IRQ_LEVEL == 0
 50	IVAR0 = EXCEP_IRQ_LEVEL0;
 51#elif CONFIG_GDBSTUB_IRQ_LEVEL == 1
 52	IVAR1 = EXCEP_IRQ_LEVEL1;
 53#elif CONFIG_GDBSTUB_IRQ_LEVEL == 2
 54	IVAR2 = EXCEP_IRQ_LEVEL2;
 55#elif CONFIG_GDBSTUB_IRQ_LEVEL == 3
 56	IVAR3 = EXCEP_IRQ_LEVEL3;
 57#elif CONFIG_GDBSTUB_IRQ_LEVEL == 4
 58	IVAR4 = EXCEP_IRQ_LEVEL4;
 59#elif CONFIG_GDBSTUB_IRQ_LEVEL == 5
 60	IVAR5 = EXCEP_IRQ_LEVEL5;
 61#else
 62#error "Unknown irq level for gdbstub."
 63#endif
 64
 65	set_intr_stub(NUM2EXCEP_IRQ_LEVEL(CONFIG_GDBSTUB_IRQ_LEVEL),
 66		gdbstub_io_rx_handler);
 67
 68	XIRQxICR(GDBPORT_SERIAL_IRQ) &= ~GxICR_REQUEST;
 69	XIRQxICR(GDBPORT_SERIAL_IRQ) =
 70		GxICR_ENABLE | NUM2GxICR_LEVEL(CONFIG_GDBSTUB_IRQ_LEVEL);
 71	tmp = XIRQxICR(GDBPORT_SERIAL_IRQ);
 72
 73	GDBPORT_SERIAL_IER = UART_IER_RDI | UART_IER_RLSI;
 74
 75	/* permit level 0 IRQs to take place */
 76	arch_local_change_intr_mask_level(
 77		NUM2EPSW_IM(CONFIG_GDBSTUB_IRQ_LEVEL + 1));
 78}
 79
 80/*
 81 * set up the GDB stub serial port baud rate timers
 82 */
 83void gdbstub_io_set_baud(unsigned baud)
 84{
 85	unsigned value;
 86	u8 lcr;
 87
 88	value = 18432000 / 16 / baud;
 89
 90	lcr = GDBPORT_SERIAL_LCR;
 91	GDBPORT_SERIAL_LCR |= UART_LCR_DLAB;
 92	GDBPORT_SERIAL_DLL = value & 0xff;
 93	GDBPORT_SERIAL_DLM = (value >> 8) & 0xff;
 94	GDBPORT_SERIAL_LCR = lcr;
 95}
 96
 97/*
 98 * wait for a character to come from the debugger
 99 */
100int gdbstub_io_rx_char(unsigned char *_ch, int nonblock)
101{
102	unsigned ix;
103	u8 ch, st;
104#if defined(CONFIG_MN10300_WD_TIMER)
105	int cpu;
106#endif
107
108	*_ch = 0xff;
109
110	if (gdbstub_rx_unget) {
111		*_ch = gdbstub_rx_unget;
112		gdbstub_rx_unget = 0;
113		return 0;
114	}
115
116 try_again:
117	/* pull chars out of the buffer */
118	ix = gdbstub_rx_outp;
119	barrier();
120	if (ix == gdbstub_rx_inp) {
121		if (nonblock)
122			return -EAGAIN;
123#ifdef CONFIG_MN10300_WD_TIMER
124	for (cpu = 0; cpu < NR_CPUS; cpu++)
125		watchdog_alert_counter[cpu] = 0;
126#endif
127		goto try_again;
128	}
129
130	ch = gdbstub_rx_buffer[ix++];
131	st = gdbstub_rx_buffer[ix++];
132	barrier();
133	gdbstub_rx_outp = ix & 0x00000fff;
134
135	if (st & UART_LSR_BI) {
136		gdbstub_proto("### GDB Rx Break Detected ###\n");
137		return -EINTR;
138	} else if (st & (UART_LSR_FE | UART_LSR_OE | UART_LSR_PE)) {
139		gdbstub_proto("### GDB Rx Error (st=%02x) ###\n", st);
140		return -EIO;
141	} else {
142		gdbstub_proto("### GDB Rx %02x (st=%02x) ###\n", ch, st);
143		*_ch = ch & 0x7f;
144		return 0;
145	}
146}
147
148/*
149 * send a character to the debugger
150 */
151void gdbstub_io_tx_char(unsigned char ch)
152{
153	FLOWCTL_SET(DTR);
154	LSR_WAIT_FOR(THRE);
155	/* FLOWCTL_WAIT_FOR(CTS); */
156
157	if (ch == 0x0a) {
158		GDBPORT_SERIAL_TX = 0x0d;
159		LSR_WAIT_FOR(THRE);
160		/* FLOWCTL_WAIT_FOR(CTS); */
161	}
162	GDBPORT_SERIAL_TX = ch;
163
164	FLOWCTL_CLEAR(DTR);
165}
166
167/*
168 * send a character to the debugger
169 */
170void gdbstub_io_tx_flush(void)
171{
172	LSR_WAIT_FOR(TEMT);
173	LSR_WAIT_FOR(THRE);
174	FLOWCTL_CLEAR(DTR);
175}