Allow reading from the mini UART. Add a check to not touch the UART unless it's been...

--HG--
branch : dtrg-videocore

diff --git a/plat/rpi/libsys/pi_uart.s b/plat/rpi/libsys/pi_uart.s
index caa9f6f..0cfed4a 100644 (file)
--- a/plat/rpi/libsys/pi_uart.s
+++ b/plat/rpi/libsys/pi_uart.s
@@ -113,12 +113,19 @@ delay2:
        mov     r0, #3
        st      r0, (r1)
 
+       ! Mark the uart as being initialised.
+       mov r0, #1
+       stb r0, __uart_status
+
        b lr
 
 ! Send a single byte.
 
 .define __sys_rawwrite
 __sys_rawwrite:
+       ldb r0, __uart_status
+       b.eq r0, #0, 1f
+
        ld r0, (sp)
        mov r1, #AUX_MU_LSR_REG
        ! loop until space available in Tx buffer
@@ -131,5 +138,27 @@ sendwait:
        mov     r1, #AUX_MU_IO_REG
        stb     r0, (r1)
 
+1:
+       b lr
+
+! Receive a single byte.
+
+.define __sys_rawread
+__sys_rawread:
+       ldb r0, __uart_status
+       b.eq r0, #0, 1b
+
+       ! receive 1 byte (returned in r0)
+       mov     r1, #AUX_MU_LSR_REG
+       mov     r2, #AUX_MU_IO_REG
+       ! loop until char available
+recvwait:
+       ld r3, (r1)
+       and     r3, #0x1
+       b.ne r3, #0x1, recvwait
+
+       ldb     r0, (r2)
+1:
        b lr
 
+.comm __uart_status, 1