initial commit

lib/mbox.c

@@ -0,0 +1,89 @@
+/*
+ * Copyright (C) 2018 bzt (bztsrc@github)
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use, copy,
+ * modify, merge, publish, distribute, sublicense, and/or sell copies
+ * of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ *
+ */
+
+#include <gpio.h>
+#include <mbox.h>
+
+/* mailbox message buffer */
+volatile unsigned int  __attribute__((aligned(16))) mbox[36];
+
+#define VIDEOCORE_MBOX  (MMIO_BASE+0x0000B880)
+#define MBOX_READ       ((volatile unsigned int*)(VIDEOCORE_MBOX+0x0))
+#define MBOX_POLL       ((volatile unsigned int*)(VIDEOCORE_MBOX+0x10))
+#define MBOX_SENDER     ((volatile unsigned int*)(VIDEOCORE_MBOX+0x14))
+#define MBOX_STATUS     ((volatile unsigned int*)(VIDEOCORE_MBOX+0x18))
+#define MBOX_CONFIG     ((volatile unsigned int*)(VIDEOCORE_MBOX+0x1C))
+#define MBOX_WRITE      ((volatile unsigned int*)(VIDEOCORE_MBOX+0x20))
+#define MBOX_RESPONSE   0x80000000
+#define MBOX_FULL       0x80000000
+#define MBOX_EMPTY      0x40000000
+
+#define MAILBOX_BASE    MMIO_BASE + 0xb880
+
+#define REQUEST_CODE        0x00000000
+#define REQUEST_SUCCEED     0x80000000
+#define REQUEST_FAILED      0x80000001
+#define TAG_REQUEST_CODE    0x00000000
+#define END_TAG             0x00000000
+
+/**
+ * Make a mailbox call. Returns 0 on failure, non-zero on success
+ */
+int mbox_call(unsigned char ch)
+{
+  unsigned int r = (((unsigned int)((unsigned long)&mbox)&~0xF) | (ch&0xF));
+  /* wait until we can write to the mailbox */
+  do{asm volatile("nop");}while(*MBOX_STATUS & MBOX_FULL);
+  /* write the address of our message to the mailbox with channel identifier */
+  *MBOX_WRITE = r;
+  /* now wait for the response */
+  while(1) {
+    /* is there a response? */
+    do{asm volatile("nop");}while(*MBOX_STATUS & MBOX_EMPTY);
+    /* is it a response to our message? */
+    if(r == *MBOX_READ)
+      /* is it a valid successful response? */
+      return mbox[1]==MBOX_RESPONSE;
+  }
+  return 0;
+}
+
+unsigned int get_board_revision(void)
+{
+  mbox[0] = 36 * 4;
+  mbox[1] = REQUEST_CODE;
+
+  // tags
+  mbox[2] = MBOX_TAG_BOARD_REVISION;
+  mbox[3] = 4;
+  mbox[4] = TAG_REQUEST_CODE;
+  mbox[5] = 0; // value buffer
+
+  mbox[6] = END_TAG;
+
+  mbox_call(MBOX_CH_PROP);
+
+  return mbox[5];
+}