Add V4L2 support

src/compat.c

@@ -56,9 +56,13 @@ int __fgetc_unlocked(FILE *stream) { return fgetc(stream); }
 double __log_finite(double x) { return log(x); }
 
 #if defined(__arm__) || defined(__aarch64__) || defined(__mips__)
+/* The 32-bit offset suits vendor libraries; V4L2 builds link none, and
+ * their libraries (ALSA) pass the libc off_t. */
+#ifndef DIVINUS_V4L2
 void *mmap(void *start, size_t len, int prot, int flags, int fd, uint32_t off) {
     return (void*)syscall(SYS_mmap2, start, len, prot, flags, fd, off >> 12);
 }
+#endif
 
 void *__mmap64(void *start, size_t len, int prot, int flags, int fd, off_t off) {
     return (void*)syscall(SYS_mmap2, start, len, prot, flags, fd, (long)(off >> 12));

src/hal/support.c

@@ -17,6 +17,7 @@ unsigned long long lastMillisTemp = 0;
 float lastReadTemp = 0.0 / 0.0;
 
 void hal_identify(void) {
+    if (v4l2_system_identify()) return;
 #if defined(__ARM_PCS_VFP)
     if (i6_system_identify()) return;
     if (i6c_system_identify()) return;

src/hal/support.h

@@ -1,6 +1,7 @@
 #include "types.h"
 #include "globals.h"
 #include "tools.h"
+#include "v4l2_hal.h"
 
 #include <linux/version.h>
 #include <stdbool.h>

src/hal/types.h

@@ -18,7 +18,8 @@ typedef enum {
     HAL_PLATFORM_V1,
     HAL_PLATFORM_V2,
     HAL_PLATFORM_V3,
-    HAL_PLATFORM_V4
+    HAL_PLATFORM_V4,
+    HAL_PLATFORM_V4L2
 } hal_platform;
 
 typedef enum {