[Blackfin] serial driver: fix bug - cache the bits of the LSR on systems where the LSR is read-to-clear

Cache the bits of the LSR on systems where the LSR is read-to-clear
so that we can safely read the LSR in random places.  this fixes
older parts where break/framing/parity/overflow was not being detected
at all in PIO mode, and this fixes newer parts where
break/framing/parity/overflow was being reported all the time
without being cleared.

Signed-off-by: Mike Frysinger <michael.frysinger@analog.com>
Signed-off-by: Bryan Wu <bryan.wu@analog.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/include/asm-blackfin/mach-bf548/bfin_serial_5xx.h b/include/asm-blackfin/mach-bf548/bfin_serial_5xx.h
index 3770aa38ee9f..8733d47747e5 100644
--- a/include/asm-blackfin/mach-bf548/bfin_serial_5xx.h
+++ b/include/asm-blackfin/mach-bf548/bfin_serial_5xx.h
@@ -32,6 +32,7 @@
 #define UART_PUT_DLH(uart,v)    bfin_write16(((uart)->port.membase + OFFSET_DLH),v)
 #define UART_PUT_LSR(uart,v)    bfin_write16(((uart)->port.membase + OFFSET_LSR),v)
 #define UART_PUT_LCR(uart,v)    bfin_write16(((uart)->port.membase + OFFSET_LCR),v)
+#define UART_CLEAR_LSR(uart)    bfin_write16(((uart)->port.membase + OFFSET_LSR), -1)
 #define UART_PUT_GCTL(uart,v)   bfin_write16(((uart)->port.membase + OFFSET_GCTL),v)
 
 #if defined(CONFIG_BFIN_UART0_CTSRTS) || defined(CONFIG_BFIN_UART1_CTSRTS)