abcmem: update the MMU setup; overlay test image with dram_bss

abcmem: actually present a reasonable memory map, and reserve memory
for the ABC80 extension memory.

max80.ld: overlay dram_bss with the test image. Once we load the test
image there is no going back anyway, and the big thing is to have it
in ROM.

fw/Makefile

@@ -42,7 +42,7 @@ ROMOBJS  = $(ROMS:.rom=.o)
 max80.elf: head.o die.o main.o dummy.o irqtable.o irqasm.o sbrk.o \
 	  console.o rtc.o romcopy.o \
 	  sdcard.o diskcache.o \
-	  abcio.o abcdisk.o \
+	  abcio.o abcdisk.o abcmem.o \
 	  memset.o memcpy.o \
 	  runtest.o start_test.o \
 	  $(ROMOBJS) \
@@ -52,7 +52,7 @@ max80.elf: head.o die.o main.o dummy.o irqtable.o irqasm.o sbrk.o \
 testimg.elf: head.o die.o test/main.o dummy.o irqtable.o irqasm.o sbrk.o \
 	  console.o rtc.o romcopy.o \
 	  sdcard.o diskcache.o \
-	  abcio.o abcdisk.o \
+	  abcio.o abcdisk.o abcmem.o \
 	  memset.o memcpy.o \
 	  testdata.o \
 	  fatfs.a

fw/abcio.h

@@ -45,4 +45,6 @@ void abc_init(void);
 void abcdisk_init(void);
 void abcdisk_io_poll(void);
 
+void abc_init_memmap(void);
+
 #endif /* ABCIO_H */

fw/abcmem.c

@@ -0,0 +1,43 @@
+#include "fw.h"
+#include "io.h"
+#include "abcio.h"
+#include "sys.h"
+
+/* Configure ABC memory map */
+struct abc_mem_init {
+    unsigned int addr;
+    uint16_t len;
+    uint8_t flags;
+    const char *data;		/* May not be const, but... */
+};
+#define RD (ABCMEMMAP_RD >> 24)
+#define WR (ABCMEMMAP_WR >> 24)
+
+extern const char rom_ufddos80[];
+
+static char __dram_bss abc80_extmem[16 << 10];
+
+static const struct abc_mem_init mem_init[] = {
+    { 0x5800,  2 << 10, RD, rom_ufddos80 },
+    { 0x8000, 16 << 10, RD|WR, abc80_extmem },
+    { -1U, 0, 0, NULL }
+};
+
+void abc_init_memmap(void)
+{
+
+    volatile uint32_t *pg = &ABCMEMMAP_PAGE(0);
+    const struct abc_mem_init *next = &mem_init[0];
+
+    for (unsigned int addr = 0; addr < 0x10000; addr += 512) {
+	if (addr >= next->addr + next->len)
+	    next++;
+
+	if (addr < next->addr) {
+	    *pg++ = 0;
+	} else {
+	    *pg++ = ((size_t)(next->data + (addr - next->addr))
+		     & SDRAM_MASK) | (next->flags << 24);
+	}
+    }
+}

fw/diskcache.c

@@ -221,8 +221,6 @@ int disk_init(void)
     con_printf("sdcard: %u/%u clusters free, clusters = %u bytes\n",
 	       freeclust, fs->n_fatent - 2, fs->csize << 9);
 
-    abcdisk_init();
-
     return 0;
 }
 

fw/main.c

@@ -14,22 +14,6 @@ IRQHANDLER(sysclock)
     set_led(count >> 3); /* 4 Hz */
 }
 
-/* Configure ABC memory map */
-static void init_abc_memmap(void)
-{
-    volatile uint32_t *pg = &ABCMEMMAP_PAGE(0);
-
-    for (unsigned int addr = 0; addr < 0x10000; addr += 512) {
-	if (addr >= 0x5800 && addr < 0x6000) {
-	    *pg++ = ABCMEMMAP_RD | addr;
-	} else if (addr >= 0x8000 && addr < 0xc000) {
-	    *pg++ = ABCMEMMAP_RD | ABCMEMMAP_WR | addr;
-	} else {
-	    *pg++ = addr;	/* Disabled */
-	}
-    }
-}
-
 static no_return killed(const char *how, size_t pc)
 {
     con_printf("ERROR: %s at 0x%08x\n", how, pc);
@@ -63,8 +47,8 @@ static void init(void)
     con_set_baudrate(115200);
     con_puts(hello);
 
+    abc_init_memmap();
     abc_init();
-    init_abc_memmap();
 
     timer_irq_count = 0;
     timer_irq_start = rdtime();

fw/max80.ld

@@ -14,6 +14,7 @@ MEMORY
 {
 	SRAM	: org = SRAM_ADDR,  len = SRAM_SIZE
 	DRAM	: org = SDRAM_ADDR, len = SDRAM_SIZE
+	DRAM2   : org = SDRAM_ADDR+SDRAM_SIZE, len = SDRAM_SIZE
 }
 
 SECTIONS
@@ -202,10 +203,17 @@ SECTIONS
 	__dram_init_end = .;
 	__dram_init_len = __dram_init_end - __dram_init_start;
 
-	/* Test program image */
-	.dram.test : ALIGN(4) {
-		KEEP(*(.dram.test*))
-	} >DRAM
+	/* Keeps ld from getting confused */
+	. = . + SDRAM_SIZE;
+
+	/* Test program image - overlays */
+	.dram.test __dram_init_end + SDRAM_SIZE :
+		   AT(SRAM_SIZE + __dram_init_len) ALIGN(4) {
+		   KEEP(*(.dram.test*))
+	} >DRAM2
+
+	/* bss can overlay the test program image */
+	. = __dram_init_end;
 
 	__dram_bss_start = .;
 	.dram.bss (NOLOAD) : ALIGN(8) {