The patch introduces the alternative configuration of the log buffer for the lwmon5 board: the storage for the log-buffer itself is OCM(on-chip memory), the log-buffer header is moved to six GPT registers (PPC440EPX_GPT0_COMP1, ..., PPC440EPX_GPT0_COMP5).

To enable this, alternative, configuration the U-Boot board configuration
file for lwmon5 includes the definitions of alternative addresses for header
(CONFIG_ALT_LH_ADDR) and buffer (CONFIG_ALT_LB_ADDR).

 The Linux shall be configured with the CONFIG_ALT_LB_LOCATION option set,
and has the BOARD_ALT_LH_ADDR and BOARD_ALT_LB_ADDR constants defined in the
lwmon5 board-specific header (arch/ppc/platforms/4xx/lwmon5.h).

Signed-off-by: Yuri Tikhonov <yur@emcraft.com>

common/cmd_bootm.c

@@ -545,11 +545,15 @@ do_bootm_linux (cmd_tbl_t *cmdtp, int flag,
 	}
 
 #ifdef CONFIG_LOGBUFFER
+#ifndef CONFIG_ALT_LB_ADDR
 	kbd=gd->bd;
 	/* Prevent initrd from overwriting logbuffer */
 	if (initrd_high < (kbd->bi_memsize-LOGBUFF_LEN-LOGBUFF_OVERHEAD))
 		initrd_high = kbd->bi_memsize-LOGBUFF_LEN-LOGBUFF_OVERHEAD;
 	debug ("## Logbuffer at 0x%08lX ", kbd->bi_memsize-LOGBUFF_LEN);
+#else
+	debug ("## Logbuffer at 0x%08lX ", CONFIG_ALT_LB_ADDR);
+#endif
 #endif
 
 	/*

common/cmd_log.c

@@ -59,14 +59,25 @@ static char buf[1024];
 static unsigned console_loglevel = 3;
 static unsigned default_message_loglevel = 4;
 static unsigned log_version = 1;
+#ifdef CONFIG_ALT_LB_ADDR
+static volatile logbuff_t *log;
+#else
 static logbuff_t *log;
+#endif
+static char *lbuf;
 
 void logbuff_init_ptrs (void)
 {
 	unsigned long tag, post_word;
 	char *s;
 
+#ifdef CONFIG_ALT_LB_ADDR
+	log = (logbuff_t *)CONFIG_ALT_LH_ADDR;
+	lbuf = (char *)CONFIG_ALT_LB_ADDR;
+#else
 	log = (logbuff_t *)(gd->bd->bi_memsize-LOGBUFF_LEN) - 1;
+	lbuf = log->buf;
+#endif
 
 	/* Set up log version */
 	if ((s = getenv ("logversion")) != NULL)
@@ -101,11 +112,26 @@ void logbuff_init_ptrs (void)
 
 void logbuff_reset (void)
 {
+#ifndef CONFIG_ALT_LB_ADDR
 	memset (log, 0, sizeof (logbuff_t));
-	if (log_version == 2)
+#endif
+	if (log_version == 2) {
 		log->v2.tag = LOGBUFF_MAGIC;
-	else
+#ifdef CONFIG_ALT_LB_ADDR
+		log->v2.start = 0;
+		log->v2.con = 0;
+		log->v2.end = 0;
+		log->v2.chars = 0;
+#endif
+	} else {
 		log->v1.tag = LOGBUFF_MAGIC;
+#ifdef CONFIG_ALT_LB_ADDR
+		log->v1.dummy = 0;
+		log->v1.start = 0;
+		log->v1.size = 0;
+		log->v1.chars = 0;
+#endif
+	}
 }
 
 int drv_logbuff_init (void)
@@ -188,7 +214,7 @@ int do_log (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
 				size = log->v1.size;
 			}
 			for (i=0; i < (size&LOGBUFF_MASK); i++) {
-				s = (char *)log->buf+((start+i)&LOGBUFF_MASK);
+				s = lbuf+((start+i)&LOGBUFF_MASK);
 				putc (*s);
 			}
 			return 0;
@@ -196,7 +222,7 @@ int do_log (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
 			logbuff_reset ();
 			return 0;
 		} else if (strcmp(argv[1],"info") == 0) {
-			printf ("Logbuffer   at  %08lx\n", (unsigned long)log->buf);
+			printf ("Logbuffer   at  %08lx\n", (unsigned long)lbuf);
 			if (log_version == 2) {
 				printf ("log_start    =  %08lx\n", log->v2.start);
 				printf ("log_end      =  %08lx\n", log->v2.end);
@@ -257,14 +283,14 @@ static int logbuff_printk(const char *line)
 		line_feed = 0;
 		for (; p < buf_end; p++) {
 			if (log_version == 2) {
-				log->buf[log->v2.end & LOGBUFF_MASK] = *p;
+				lbuf[log->v2.end & LOGBUFF_MASK] = *p;
 				log->v2.end++;
 				if (log->v2.end - log->v2.start > LOGBUFF_LEN)
 					log->v2.start++;
 				log->v2.chars++;
 			}
 			else {
-				log->buf[(log->v1.start + log->v1.size) &
+				lbuf[(log->v1.start + log->v1.size) &
 					 LOGBUFF_MASK] = *p;
 				if (log->v1.size < LOGBUFF_LEN)
 					log->v1.size++;

include/configs/lwmon5.h

@@ -244,6 +244,8 @@
 
 #define CFG_POST_CACHE_ADDR	0x7fff0000 /* free virtual address	*/
 #define CONFIG_LOGBUFFER
+#define CONFIG_ALT_LH_ADDR	(CFG_PERIPHERAL_BASE + GPT0_COMP1)
+#define CONFIG_ALT_LB_ADDR	(CFG_OCM_BASE)
 #define CFG_CONSOLE_IS_IN_ENV /* Otherwise it catches logbuffer as output */
 
 /*-----------------------------------------------------------------------

include/ppc440.h

@@ -1434,6 +1434,8 @@
 #define GPT0_COMP5			0x00000094
 #define GPT0_COMP4			0x00000090
 #define GPT0_COMP3			0x0000008C
+#define GPT0_COMP2			0x00000088
+#define GPT0_COMP1			0x00000084
 
 #if defined(CONFIG_440EPX) || defined(CONFIG_440GRX)
 #define SDR0_USB2D0CR                 0x0320

lib_ppc/board.c

@@ -436,10 +436,12 @@ void board_init_f (ulong bootflag)
 	addr = CFG_SDRAM_BASE + get_effective_memsize();
 
 #ifdef CONFIG_LOGBUFFER
+#ifndef CONFIG_ALT_LB_ADDR
 	/* reserve kernel log buffer */
 	addr -= (LOGBUFF_RESERVE);
 	debug ("Reserving %dk for kernel logbuffer at %08lx\n", LOGBUFF_LEN, addr);
 #endif
+#endif
 
 #ifdef CONFIG_PRAM
 	/*
@@ -1126,8 +1128,10 @@ void board_init_r (gd_t *id, ulong dest_addr)
 		pram=0;
 #endif
 #ifdef CONFIG_LOGBUFFER
+#ifndef CONFIG_ALT_LB_ADDR
 		/* Also take the logbuffer into account (pram is in kB) */
 		pram += (LOGBUFF_LEN+LOGBUFF_OVERHEAD)/1024;
+#endif
 #endif
 		sprintf ((char *)memsz, "%ldk", (bd->bi_memsize / 1024) - pram);
 		setenv ("mem", (char *)memsz);