raspi: detect raspberry pi model, use 3 mbps for 3A+ and 3B+

port/raspi/Makefile

@@ -16,6 +16,7 @@ CORE += \
 	main.c \
 	wav_util.c 					\
 	btstack_stdin_posix.c \
+	raspi_get_model.c 
 
 # examples
 include ${BTSTACK_ROOT}/example/Makefile.inc

port/raspi/main.c

@@ -73,6 +73,8 @@
 #include "btstack_chipset_bcm_download_firmware.h"
 #include "btstack_control_raspi.h"
 
+#include "raspi_get_model.h"
+
 int btstack_main(int argc, const char * argv[]);
 
 typedef enum  {
@@ -322,12 +324,16 @@ int main(int argc, const char * argv[]){
             transport_config.flowcontrol   = 0;
             break;
         case UART_HARDWARE_FLOW:
-            // Raspberry Pi Zero W
+            // Raspberry Pi Zero W gpio 45
             // Raspberry Pi 3A+ vgpio 129 but WLAN + BL
             // Raspberry Pi 3B+ vgpio 129 but WLAN + BL
-            bt_reg_en_pin = 45;
+            transport_config.baudrate_main = 3000000;
-            transport_config.baudrate_main = 921600;
             transport_config.flowcontrol = 1;
+
+            // 3 mbps does not work on Zero W (investigation pending)
+            if (raspi_get_model() == MODEL_ZERO_W){
+                transport_config.baudrate_main = 921600;
+            }
             break;
     }
     printf("%s, %u, BT_REG_EN at GPIO %u\n", transport_config.flowcontrol ? "H4":"H5", transport_config.baudrate_main, bt_reg_en_pin);

port/raspi/raspi_get_model.c

@@ -0,0 +1,59 @@
+
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "raspi_get_model.h"
+
+/**
+ * Raspberry Pi model detection based on,
+ * https://elinux.org/RPi_HardwareHistory
+**/
+int raspi_get_model()
+{
+    FILE *f = fopen( "/proc/cpuinfo", "rb" );
+    if( f == NULL )
+    {
+        perror( "can't open cpuinfo!" );
+        return MODEL_UNKNOWN;
+    }
+
+    int ret = 0;
+    uint32_t revision = 0;
+    uint32_t model = MODEL_UNKNOWN;
+    char line[100] = { 0 };
+    char *ptr = NULL;
+    for(; ret < 1;)
+    {
+        ptr = fgets( line, 100, f );
+        if( ptr == NULL )
+            break;
+        ret = sscanf( line, "Revision : %x\n", &revision );
+    }
+    
+    fclose( f );
+    
+    switch( revision )
+    {
+    case 0x9000c1:
+        model = MODEL_ZERO_W;
+        break;
+    case 0xa02082:
+    case 0xa22082:
+    case 0xa32082:
+        model = MODEL_3B;
+        break;
+    case 0xa020d3:
+        model = MODEL_3BPLUS;
+        break;
+    case 0x9020e0:
+        model = MODEL_3APLUS;
+        break;
+    default:
+        break;
+    }
+    
+    return model;
+}
+
+

port/raspi/raspi_get_model.h

@@ -0,0 +1,13 @@
+#ifndef _RASPI_GET_MODEL_
+#define _RASPI_GET_MODEL_
+
+#define MODEL_UNKNOWN   0
+#define MODEL_ZERO_W    1
+#define MODEL_3B        2
+#define MODEL_3BPLUS    3
+#define MODEL_3APLUS    4
+
+int raspi_get_model();
+
+#endif // _RASPI_GET_MODEL_
+