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Allow reading from the mini UART. Add a check to not touch the UART unless it's been initialised (in case of accidents when running in kernel mode).

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--HG--
branch : dtrg-videocore
This commit is contained in:
David Given 2013-05-26 18:58:54 +01:00
parent 366cd10194
commit e01f00e320
1 changed files with 29 additions and 0 deletions
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29
plat/rpi/libsys/pi_uart.s
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@ -113,12 +113,19 @@ delay2:
mov r0, #3 mov r0, #3
st r0, (r1) st r0, (r1)
! Mark the uart as being initialised.
mov r0, #1
stb r0, __uart_status
b lr b lr
! Send a single byte. ! Send a single byte.
.define __sys_rawwrite .define __sys_rawwrite
__sys_rawwrite: __sys_rawwrite:
ldb r0, __uart_status
b.eq r0, #0, 1f
ld r0, (sp) ld r0, (sp)
mov r1, #AUX_MU_LSR_REG mov r1, #AUX_MU_LSR_REG
! loop until space available in Tx buffer ! loop until space available in Tx buffer
@ -131,5 +138,27 @@ sendwait:
mov r1, #AUX_MU_IO_REG mov r1, #AUX_MU_IO_REG
stb r0, (r1) stb r0, (r1)
1:
b lr 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