diff options
| author | Russell King <rmk@dyn-67.arm.linux.org.uk> | 2005-06-23 15:05:41 +0100 |
|---|---|---|
| committer | Russell King <rmk@dyn-67.arm.linux.org.uk> | 2005-06-23 15:05:41 +0100 |
| commit | 55d3b282b90620e02e825304a9433732a84c58a5 (patch) | |
| tree | ba48375ac5262a8587eb6237134ed0aa57e7174a | |
| parent | 4ba5e35daa90871fcb9b01f5ad1e5723343cc0a9 (diff) | |
[PATCH] Serial: Mobility's 16550A ports need a helping hand
The Mobility 16550A serial ports don't behave the same as standard
16550A ports, and need a helping hand to get them going once the
transmitter has drained and been disabled.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
| -rw-r--r-- | drivers/serial/8250.c | 31 | ||||
| -rw-r--r-- | drivers/serial/8250.h | 1 |
2 files changed, 32 insertions, 0 deletions
diff --git a/drivers/serial/8250.c b/drivers/serial/8250.c index 27cc288e91d..341c644591a 100644 --- a/drivers/serial/8250.c +++ b/drivers/serial/8250.c @@ -1027,6 +1027,8 @@ static void serial8250_stop_tx(struct uart_port *port, unsigned int tty_stop) } } +static void transmit_chars(struct uart_8250_port *up); + static void serial8250_start_tx(struct uart_port *port, unsigned int tty_start) { struct uart_8250_port *up = (struct uart_8250_port *)port; @@ -1034,6 +1036,14 @@ static void serial8250_start_tx(struct uart_port *port, unsigned int tty_start) if (!(up->ier & UART_IER_THRI)) { up->ier |= UART_IER_THRI; serial_out(up, UART_IER, up->ier); + + if (up->capabilities & UART_BUG_TXEN) { + unsigned char lsr, iir; + lsr = serial_in(up, UART_LSR); + iir = serial_in(up, UART_IIR); + if (lsr & UART_LSR_TEMT && iir & UART_IIR_NO_INT) + transmit_chars(up); + } } /* * We only do this from uart_start @@ -1439,6 +1449,7 @@ static int serial8250_startup(struct uart_port *port) { struct uart_8250_port *up = (struct uart_8250_port *)port; unsigned long flags; + unsigned char lsr, iir; int retval; up->capabilities = uart_config[up->port.type].flags; @@ -1542,6 +1553,26 @@ static int serial8250_startup(struct uart_port *port) up->port.mctrl |= TIOCM_OUT2; serial8250_set_mctrl(&up->port, up->port.mctrl); + + /* + * Do a quick test to see if we receive an + * interrupt when we enable the TX irq. + */ + serial_outp(up, UART_IER, UART_IER_THRI); + lsr = serial_in(up, UART_LSR); + iir = serial_in(up, UART_IIR); + serial_outp(up, UART_IER, 0); + + if (lsr & UART_LSR_TEMT && iir & UART_IIR_NO_INT) { + if (!(up->capabilities & UART_BUG_TXEN)) { + up->capabilities |= UART_BUG_TXEN; + pr_debug("ttyS%d - enabling bad tx status workarounds\n", + port->line); + } + } else { + up->capabilities &= ~UART_BUG_TXEN; + } + spin_unlock_irqrestore(&up->port.lock, flags); /* diff --git a/drivers/serial/8250.h b/drivers/serial/8250.h index cd5c3dd2d91..9225c82faeb 100644 --- a/drivers/serial/8250.h +++ b/drivers/serial/8250.h @@ -52,6 +52,7 @@ struct serial8250_config { #define UART_CAP_UUE (1 << 12) /* UART needs IER bit 6 set (Xscale) */ #define UART_BUG_QUOT (1 << 0) /* UART has buggy quot LSB */ +#define UART_BUG_TXEN (1 << 1) /* UART has buggy TX IIR status */ #if defined(__i386__) && (defined(CONFIG_M386) || defined(CONFIG_M486)) #define _INLINE_ inline |