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Linux/arch/blackfin/kernel/early_printk.c

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  1 /*
  2  * allow a console to be used for early printk
  3  * derived from arch/x86/kernel/early_printk.c
  4  *
  5  * Copyright 2007-2009 Analog Devices Inc.
  6  *
  7  * Licensed under the GPL-2
  8  */
  9 
 10 #include <linux/kernel.h>
 11 #include <linux/sched/debug.h>
 12 #include <linux/init.h>
 13 #include <linux/serial_core.h>
 14 #include <linux/console.h>
 15 #include <linux/string.h>
 16 #include <linux/reboot.h>
 17 #include <asm/blackfin.h>
 18 #include <asm/irq_handler.h>
 19 #include <asm/early_printk.h>
 20 
 21 #ifdef CONFIG_SERIAL_BFIN
 22 extern struct console *bfin_earlyserial_init(unsigned int port,
 23                                                 unsigned int cflag);
 24 #endif
 25 #ifdef CONFIG_BFIN_JTAG_COMM
 26 extern struct console *bfin_jc_early_init(void);
 27 #endif
 28 
 29 /* Default console */
 30 #define DEFAULT_PORT 0
 31 #define DEFAULT_CFLAG CS8|B57600
 32 
 33 /* Default console for early crashes */
 34 #define DEFAULT_EARLY_PORT "serial,uart0,57600"
 35 
 36 #ifdef CONFIG_SERIAL_CORE
 37 /* What should get here is "0,57600" */
 38 static struct console * __init earlyserial_init(char *buf)
 39 {
 40         int baud, bit;
 41         char parity;
 42         unsigned int serial_port = DEFAULT_PORT;
 43         unsigned int cflag = DEFAULT_CFLAG;
 44 
 45         serial_port = simple_strtoul(buf, &buf, 10);
 46         buf++;
 47 
 48         cflag = 0;
 49         baud = simple_strtoul(buf, &buf, 10);
 50         switch (baud) {
 51         case 1200:
 52                 cflag |= B1200;
 53                 break;
 54         case 2400:
 55                 cflag |= B2400;
 56                 break;
 57         case 4800:
 58                 cflag |= B4800;
 59                 break;
 60         case 9600:
 61                 cflag |= B9600;
 62                 break;
 63         case 19200:
 64                 cflag |= B19200;
 65                 break;
 66         case 38400:
 67                 cflag |= B38400;
 68                 break;
 69         case 115200:
 70                 cflag |= B115200;
 71                 break;
 72         default:
 73                 cflag |= B57600;
 74         }
 75 
 76         parity = buf[0];
 77         buf++;
 78         switch (parity) {
 79         case 'e':
 80                 cflag |= PARENB;
 81                 break;
 82         case 'o':
 83                 cflag |= PARODD;
 84                 break;
 85         }
 86 
 87         bit = simple_strtoul(buf, &buf, 10);
 88         switch (bit) {
 89         case 5:
 90                 cflag |= CS5;
 91                 break;
 92         case 6:
 93                 cflag |= CS6;
 94                 break;
 95         case 7:
 96                 cflag |= CS7;
 97                 break;
 98         default:
 99                 cflag |= CS8;
100         }
101 
102 #ifdef CONFIG_SERIAL_BFIN
103         return bfin_earlyserial_init(serial_port, cflag);
104 #else
105         return NULL;
106 #endif
107 
108 }
109 #endif
110 
111 int __init setup_early_printk(char *buf)
112 {
113 
114         /* Crashing in here would be really bad, so check both the var
115            and the pointer before we start using it
116          */
117         if (!buf)
118                 return 0;
119 
120         if (!*buf)
121                 return 0;
122 
123         if (early_console != NULL)
124                 return 0;
125 
126 #ifdef CONFIG_SERIAL_BFIN
127         /* Check for Blackfin Serial */
128         if (!strncmp(buf, "serial,uart", 11)) {
129                 buf += 11;
130                 early_console = earlyserial_init(buf);
131         }
132 #endif
133 
134 #ifdef CONFIG_BFIN_JTAG_COMM
135         /* Check for Blackfin JTAG */
136         if (!strncmp(buf, "jtag", 4)) {
137                 buf += 4;
138                 early_console = bfin_jc_early_init();
139         }
140 #endif
141 
142 #ifdef CONFIG_FB
143                 /* TODO: add framebuffer console support */
144 #endif
145 
146         if (likely(early_console)) {
147                 early_console->flags |= CON_BOOT;
148 
149                 register_console(early_console);
150                 printk(KERN_INFO "early printk enabled on %s%d\n",
151                         early_console->name,
152                         early_console->index);
153         }
154 
155         return 0;
156 }
157 
158 /*
159  * Set up a temporary Event Vector Table, so if something bad happens before
160  * the kernel is fully started, it doesn't vector off into somewhere we don't
161  * know
162  */
163 
164 asmlinkage void __init init_early_exception_vectors(void)
165 {
166         u32 evt;
167         SSYNC();
168 
169         /*
170          * This starts up the shadow buffer, incase anything crashes before
171          * setup arch
172          */
173         mark_shadow_error();
174         early_shadow_puts(linux_banner);
175         early_shadow_stamp();
176 
177         if (CPUID != bfin_cpuid()) {
178                 early_shadow_puts("Running on wrong machine type, expected");
179                 early_shadow_reg(CPUID, 16);
180                 early_shadow_puts(", but running on");
181                 early_shadow_reg(bfin_cpuid(), 16);
182                 early_shadow_puts("\n");
183         }
184 
185         /* cannot program in software:
186          * evt0 - emulation (jtag)
187          * evt1 - reset
188          */
189         for (evt = EVT2; evt <= EVT15; evt += 4)
190                 bfin_write32(evt, early_trap);
191         CSYNC();
192 
193         /* Set all the return from interrupt, exception, NMI to a known place
194          * so if we do a RETI, RETX or RETN by mistake - we go somewhere known
195          * Note - don't change RETS - we are in a subroutine, or
196          * RETE - since it might screw up if emulator is attached
197          */
198         asm("\tRETI = %0; RETX = %0; RETN = %0;\n"
199                 : : "p"(early_trap));
200 
201 }
202 
203 __attribute__((__noreturn__))
204 asmlinkage void __init early_trap_c(struct pt_regs *fp, void *retaddr)
205 {
206         /* This can happen before the uart is initialized, so initialize
207          * the UART now (but only if we are running on the processor we think
208          * we are compiled for - otherwise we write to MMRs that don't exist,
209          * and cause other problems. Nothing comes out the UART, but it does
210          * end up in the __buf_log.
211          */
212         if (likely(early_console == NULL) && CPUID == bfin_cpuid())
213                 setup_early_printk(DEFAULT_EARLY_PORT);
214 
215         if (!shadow_console_enabled()) {
216                 /* crap - we crashed before setup_arch() */
217                 early_shadow_puts("panic before setup_arch\n");
218                 early_shadow_puts("IPEND:");
219                 early_shadow_reg(fp->ipend, 16);
220                 if (fp->seqstat & SEQSTAT_EXCAUSE) {
221                         early_shadow_puts("\nEXCAUSE:");
222                         early_shadow_reg(fp->seqstat & SEQSTAT_EXCAUSE, 8);
223                 }
224                 if (fp->seqstat & SEQSTAT_HWERRCAUSE) {
225                         early_shadow_puts("\nHWERRCAUSE:");
226                         early_shadow_reg(
227                                 (fp->seqstat & SEQSTAT_HWERRCAUSE) >> 14, 8);
228                 }
229                 early_shadow_puts("\nErr @");
230                 if (fp->ipend & EVT_EVX)
231                         early_shadow_reg(fp->retx, 32);
232                 else
233                         early_shadow_reg(fp->pc, 32);
234 #ifdef CONFIG_DEBUG_BFIN_HWTRACE_ON
235                 early_shadow_puts("\nTrace:");
236                 if (likely(bfin_read_TBUFSTAT() & TBUFCNT)) {
237                         while (bfin_read_TBUFSTAT() & TBUFCNT) {
238                                 early_shadow_puts("\nT  :");
239                                 early_shadow_reg(bfin_read_TBUF(), 32);
240                                 early_shadow_puts("\n S :");
241                                 early_shadow_reg(bfin_read_TBUF(), 32);
242                         }
243                 }
244 #endif
245                 early_shadow_puts("\nUse bfin-elf-addr2line to determine "
246                         "function names\n");
247                 /*
248                  * We should panic(), but we can't - since panic calls printk,
249                  * and printk uses memcpy.
250                  * we want to reboot, but if the machine type is different,
251                  * can't due to machine specific reboot sequences
252                  */
253                 if (CPUID == bfin_cpuid()) {
254                         early_shadow_puts("Trying to restart\n");
255                         machine_restart("");
256                 }
257 
258                 early_shadow_puts("Halting, since it is not safe to restart\n");
259                 while (1)
260                         asm volatile ("EMUEXCPT; IDLE;\n");
261 
262         } else {
263                 printk(KERN_EMERG "Early panic\n");
264                 show_regs(fp);
265                 dump_bfin_trace_buffer();
266         }
267 
268         panic("Died early");
269 }
270 
271 early_param("earlyprintk", setup_early_printk);
272 

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