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Blackfin: fix up UART status bit handling

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Some Blackfin UARTs are read-to-clear while others are write-to-clear.
This can cause problems when we poll the LSR and then later try and handle
any errors detected.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
This commit is contained in:
Mike Frysinger 2008-04-09 02:02:07 -04:00
parent ae0910298f
commit f177f4250c
1 changed files with 60 additions and 12 deletions
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72
cpu/blackfin/serial.c
View file

@ -35,6 +35,32 @@
#include "serial.h" #include "serial.h"
#ifdef CONFIG_DEBUG_SERIAL
uint16_t cached_lsr[256];
uint16_t cached_rbr[256];
size_t cache_count;
/* The LSR is read-to-clear on some parts, so we have to make sure status
* bits aren't inadvertently lost when doing various tests.
*/
static uint16_t uart_lsr_save;
static uint16_t uart_lsr_read(void)
{
uint16_t lsr = *pUART_LSR;
uart_lsr_save |= (lsr & (OE|PE|FE|BI));
return lsr | uart_lsr_save;
}
/* Just do the clear for everyone since it can't hurt. */
static void uart_lsr_clear(void)
{
uart_lsr_save = 0;
*pUART_LSR |= -1;
}
#else
static inline uint16_t uart_lsr_read(void) { return *pUART_LSR; }
static inline void uart_lsr_clear(void) { *pUART_LSR = -1; }
#endif
/* Symbol for our assembly to call. */ /* Symbol for our assembly to call. */
void serial_set_baud(uint32_t baud) void serial_set_baud(uint32_t baud)
{ {
@ -61,6 +87,12 @@ int serial_init(void)
{ {
serial_initialize(); serial_initialize();
serial_setbrg(); serial_setbrg();
uart_lsr_clear();
#ifdef CONFIG_DEBUG_SERIAL
cache_count = 0;
memset(cached_lsr, 0x00, sizeof(cached_lsr));
memset(cached_rbr, 0x00, sizeof(cached_rbr));
#endif
return 0; return 0;
} }
@ -73,7 +105,7 @@ void serial_putc(const char c)
WATCHDOG_RESET(); WATCHDOG_RESET();
/* wait for the hardware fifo to clear up */ /* wait for the hardware fifo to clear up */
while (!(*pUART_LSR & THRE)) while (!(uart_lsr_read() & THRE))
continue; continue;
/* queue the character for transmission */ /* queue the character for transmission */
@ -83,38 +115,54 @@ void serial_putc(const char c)
WATCHDOG_RESET(); WATCHDOG_RESET();
/* wait for the byte to be shifted over the line */ /* wait for the byte to be shifted over the line */
while (!(*pUART_LSR & TEMT)) while (!(uart_lsr_read() & TEMT))
continue; continue;
} }
int serial_tstc(void) int serial_tstc(void)
{ {
WATCHDOG_RESET(); WATCHDOG_RESET();
return (*pUART_LSR & DR) ? 1 : 0; return (uart_lsr_read() & DR) ? 1 : 0;
} }
int serial_getc(void) int serial_getc(void)
{ {
uint16_t uart_lsr_val, uart_rbr_val; uint16_t uart_rbr_val;
/* wait for data ! */ /* wait for data ! */
while (!serial_tstc()) while (!serial_tstc())
continue; continue;
/* clear the status and grab the new byte */ /* grab the new byte */
uart_lsr_val = *pUART_LSR;
uart_rbr_val = *pUART_RBR; uart_rbr_val = *pUART_RBR;
#ifdef CONFIG_DEBUG_SERIAL
/* grab & clear the LSR */
uint16_t uart_lsr_val = uart_lsr_read();
cached_lsr[cache_count] = uart_lsr_val;
cached_rbr[cache_count] = uart_rbr_val;
cache_count = (cache_count + 1) % ARRAY_SIZE(cached_lsr);
if (uart_lsr_val & (OE|PE|FE|BI)) { if (uart_lsr_val & (OE|PE|FE|BI)) {
/* Some parts are read-to-clear while others are uint16_t dll, dlh;
* write-to-clear. Just do the write for everyone printf("\n[SERIAL ERROR]\n");
* since it cant hurt (other than code size). ACCESS_LATCH();
*/ dll = *pUART_DLL;
*pUART_LSR = (OE|PE|FE|BI); dlh = *pUART_DLH;
ACCESS_PORT_IER();
printf("\tDLL=0x%x DLH=0x%x\n", dll, dlh);
do {
--cache_count;
printf("\t%3i: RBR=0x%02x LSR=0x%02x\n", cache_count,
cached_rbr[cache_count], cached_lsr[cache_count]);
} while (cache_count > 0);
return -1; return -1;
} }
#endif
uart_lsr_clear();
return uart_rbr_val & 0xFF; return uart_rbr_val;
} }
void serial_puts(const char *s) void serial_puts(const char *s)