From 93bf62580a68533dc8252b9a2a055c02f34ecb67 Mon Sep 17 00:00:00 2001 From: Christian Cunningham Date: Thu, 24 Mar 2022 09:38:08 -0700 Subject: Modularized --- kernel/graphics/mbox.c | 37 +++++++++++++++++++++++++++++++++++++ 1 file changed, 37 insertions(+) create mode 100644 kernel/graphics/mbox.c (limited to 'kernel/graphics/mbox.c') diff --git a/kernel/graphics/mbox.c b/kernel/graphics/mbox.c new file mode 100644 index 0000000..0dac497 --- /dev/null +++ b/kernel/graphics/mbox.c @@ -0,0 +1,37 @@ +#include + +/* 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 + +/** + * 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; +} -- cgit v1.2.1