Now compiles on the Raspberry Pi 2, although it does not work

README.md

@@ -10,7 +10,7 @@ It is based on the FM transmitter created by [Oliver Mattos and Oskar Weigl](htt
 
 ![](doc/vfd_display.jpg)
 
-**NEW: now supports any sample rate for audio files, and generates FM-Stereo signals!**
+**Note: the program currently runs only on the Raspberry Pi 1. Although it will compile on the Raspberry Pi 2, it will not work. This seems to be due to the different memory architecture of the Raspberry Pi 2, which prevents the easy manipulation of DMA buffers from userspace because of caching. A clean solution would involve a kernel module to perform all the DMA work, but it requires time. Any help is appreciated :-)**
 
 ## How to use it?
 

src/Makefile

@@ -5,13 +5,21 @@ STD_CFLAGS = -Wall -std=gnu99 -c -g -O3
 UNAME := $(shell uname -m)
 
 ifeq ($(UNAME), armv6l)
-	CFLAGS = $(STD_CFLAGS) -march=armv6 -mtune=arm1176jzf-s -mfloat-abi=hard -mfpu=vfp -ffast-math
+	CFLAGS = $(STD_CFLAGS) -march=armv6 -mtune=arm1176jzf-s -mfloat-abi=hard -mfpu=vfp -ffast-math -DRASPI=1
+	TARGET = pi1
+else ifeq ($(UNAME), armv7l)
+	CFLAGS = $(STD_CFLAGS) -march=armv7-a -mtune=arm1176jzf-s -mfloat-abi=hard -mfpu=vfp -ffast-math -DRASPI=2
+	TARGET = pi2
+else
+	CFLAGS = $(STD_CFLAGS)
+	TARGET = other
+endif
+
+ifneq ($(TARGET), other)
 
 app: rds.o waveforms.o pi_fm_rds.o fm_mpx.o control_pipe.o
 	$(CC) -o pi_fm_rds rds.o waveforms.o pi_fm_rds.o fm_mpx.o control_pipe.o -lm -lsndfile
 
-else
-	CFLAGS = $(STD_CFLAGS)
 endif
 
 

src/pi_fm_rds.c

@@ -103,6 +103,13 @@
 #include "fm_mpx.h"
 #include "control_pipe.h"
 
+#if (RASPI)==1
+#define IO_BASE 0x20000000
+#elif (RASPI)==2
+#define IO_BASE 0x3F000000
+#else
+#error Unknown Raspberry Pi version (variable RASPI)
+#endif
 
 #define NUM_SAMPLES        50000
 #define NUM_CBS            (NUM_SAMPLES * 2)
@@ -119,13 +126,13 @@
 #define DMA_CONBLK_AD        (0x04/4)
 #define DMA_DEBUG        (0x20/4)
 
-#define DMA_BASE        0x20007000
+#define DMA_BASE        (IO_BASE + 0x7000)
 #define DMA_LEN            0x24
-#define PWM_BASE        0x2020C000
+#define PWM_BASE        (IO_BASE + 0x20C000)
 #define PWM_LEN            0x28
-#define CLK_BASE            0x20101000
+#define CLK_BASE            (IO_BASE + 0x101000)
 #define CLK_LEN            0xA8
-#define GPIO_BASE        0x20200000
+#define GPIO_BASE        (IO_BASE + 0x200000)
 #define GPIO_LEN        0xB4
 
 
@@ -252,7 +259,7 @@ mem_phys_to_virt(uint32_t phys)
 static void *
 map_peripheral(uint32_t base, uint32_t len)
 {
-    int fd = open("/dev/mem", O_RDWR);
+    int fd = open("/dev/mem", O_RDWR | O_SYNC);
     void * vaddr;
 
     if (fd < 0)
@@ -308,7 +315,7 @@ int tx(uint32_t carrier_freq, char *audio_file, uint16_t pi, char *ps, char *rt,
         fatal("Failed to open %s: %m\n", pagemap_fn);
     if (lseek(fd, (unsigned long)virtbase >> 9, SEEK_SET) != (unsigned long)virtbase >> 9)
         fatal("Failed to seek on %s: %m\n", pagemap_fn);
-//    printf("Page map:\n");
+    printf("Page map:\n");
     for (i = 0; i < NUM_PAGES; i++) {
         uint64_t pfn;
         page_map[i].virtaddr = virtbase + i * PAGE_SIZE;
@@ -319,7 +326,7 @@ int tx(uint32_t carrier_freq, char *audio_file, uint16_t pi, char *ps, char *rt,
         if (((pfn >> 55)&0xfbf) != 0x10c)  // pagemap bits: https://www.kernel.org/doc/Documentation/vm/pagemap.txt
             fatal("Page %d not present (pfn 0x%016llx)\n", i, pfn);
         page_map[i].physaddr = (uint32_t)pfn << PAGE_SHIFT | 0x40000000;
-//        printf("  %2d: %8p ==> 0x%08x [0x%016llx]\n", i, page_map[i].virtaddr, page_map[i].physaddr, pfn);
+        printf("  %2d: %8p ==> 0x%08x [0x%016llx]\n", i, page_map[i].virtaddr, page_map[i].physaddr, pfn);
     }
 
     // GPIO4 needs to be ALT FUNC 0 to otuput the clock