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Commit 8851c71e authored by Mike Frysinger's avatar Mike Frysinger Committed by Bryan Wu
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[Blackfin] serial driver: rework break flood anomaly handling to be more... 


[Blackfin] serial driver: rework break flood anomaly handling to be more robust/realistic about what we can actually work around

Signed-off-by: default avatarMike Frysinger <michael.frysinger@analog.com>
Signed-off-by: default avatarBryan Wu <bryan.wu@analog.com>
parent 0bcfd70e

drivers/serial/bfin_5xx.c

+52 −14
Original line number Diff line number Diff line
@@ -206,12 +206,20 @@ int kgdb_get_debug_char(void) 
}

#endif



#if ANOMALY_05000230 && defined(CONFIG_SERIAL_BFIN_PIO)

# define UART_GET_ANOMALY_THRESHOLD(uart)    ((uart)->anomaly_threshold)

# define UART_SET_ANOMALY_THRESHOLD(uart, v) ((uart)->anomaly_threshold = (v))

#else

# define UART_GET_ANOMALY_THRESHOLD(uart)    0

# define UART_SET_ANOMALY_THRESHOLD(uart, v)

#endif



#ifdef CONFIG_SERIAL_BFIN_PIO

static void bfin_serial_rx_chars(struct bfin_serial_port *uart)

{

	struct tty_struct *tty = uart->port.info->tty;

	unsigned int status, ch, flg;

	static int in_break = 0;

	static struct timeval anomaly_start = { .tv_sec = 0 };

#ifdef CONFIG_KGDB_UART

	struct pt_regs *regs = get_irq_regs();

#endif
@@ -244,28 +252,56 @@ static void bfin_serial_rx_chars(struct bfin_serial_port *uart) 
#endif



	if (ANOMALY_05000230) {

		/* The BF533 family of processors have a nice misbehavior where

		 * they continuously generate characters for a "single" break.

		/* The BF533 (and BF561) family of processors have a nice anomaly

		 * where they continuously generate characters for a "single" break.

		 * We have to basically ignore this flood until the "next" valid

		 * character comes across.  All other Blackfin families operate

		 * properly though.

		 * character comes across.  Due to the nature of the flood, it is

		 * not possible to reliably catch bytes that are sent too quickly

		 * after this break.  So application code talking to the Blackfin

		 * which sends a break signal must allow at least 1.5 character

		 * times after the end of the break for things to stabilize.  This

		 * timeout was picked as it must absolutely be larger than 1

		 * character time +/- some percent.  So 1.5 sounds good.  All other

		 * Blackfin families operate properly.  Woo.

		 * Note: While Anomaly 05000230 does not directly address this,

		 *       the changes that went in for it also fixed this issue.

		 *       That anomaly was fixed in 0.5+ silicon.  I like bunnies.

		 */

		if (in_break) {

			if (ch != 0) {

				in_break = 0;

				ch = UART_GET_CHAR(uart);

				if (bfin_revid() < 5)

					return;

			} else

		if (anomaly_start.tv_sec) {

			struct timeval curr;

			suseconds_t usecs;



			if ((~ch & (~ch + 1)) & 0xff)

				goto known_good_char;



			do_gettimeofday(&curr);

			if (curr.tv_sec - anomaly_start.tv_sec > 1)

				goto known_good_char;



			usecs = 0;

			if (curr.tv_sec != anomaly_start.tv_sec)

				usecs += USEC_PER_SEC;

			usecs += curr.tv_usec - anomaly_start.tv_usec;



			if (usecs > UART_GET_ANOMALY_THRESHOLD(uart))

				goto known_good_char;



			if (ch)

				anomaly_start.tv_sec = 0;

			else

				anomaly_start = curr;



			return;



 known_good_char:

			anomaly_start.tv_sec = 0;

		}

	}



	if (status & BI) {

		if (ANOMALY_05000230)

			in_break = 1;

			if (bfin_revid() < 5)

				do_gettimeofday(&anomaly_start);

		uart->port.icount.brk++;

		if (uart_handle_break(&uart->port))

			goto ignore_char;
@@ -778,6 +814,8 @@ bfin_serial_set_termios(struct uart_port *port, struct ktermios *termios, 
	quot = uart_get_divisor(port, baud);

	spin_lock_irqsave(&uart->port.lock, flags);



	UART_SET_ANOMALY_THRESHOLD(uart, USEC_PER_SEC / baud * 15);



	do {

		lsr = UART_GET_LSR(uart);

	} while (!(lsr & TEMT));

include/asm-blackfin/mach-bf533/bfin_serial_5xx.h

+3 −0
Original line number Diff line number Diff line
@@ -57,6 +57,9 @@ struct bfin_serial_port { 
	struct work_struct	tx_dma_workqueue;

#else

	struct work_struct 	cts_workqueue;

# if ANOMALY_05000230

	unsigned int anomaly_threshold;

# endif

#endif

#ifdef CONFIG_SERIAL_BFIN_CTSRTS

	int			cts_pin;

include/asm-blackfin/mach-bf561/bfin_serial_5xx.h

+3 −0
Original line number Diff line number Diff line
@@ -57,6 +57,9 @@ struct bfin_serial_port { 
	struct work_struct	tx_dma_workqueue;

#else

	struct work_struct 	cts_workqueue;

# if ANOMALY_05000230

	unsigned int anomaly_threshold;

# endif

#endif

#ifdef CONFIG_SERIAL_BFIN_CTSRTS

	int			cts_pin;