diff options
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/serial/8250.c | 178 |
1 files changed, 134 insertions, 44 deletions
diff --git a/drivers/serial/8250.c b/drivers/serial/8250.c index 2964ca9df5a0..98ec86185328 100644 --- a/drivers/serial/8250.c +++ b/drivers/serial/8250.c @@ -364,6 +364,23 @@ serial_out(struct uart_8250_port *up, int offset, int value) } } +static void +serial_out_sync(struct uart_8250_port *up, int offset, int value) +{ + switch (up->port.iotype) { + case UPIO_MEM: + case UPIO_MEM32: +#ifdef CONFIG_SERIAL_8250_AU1X00 + case UPIO_AU: +#endif + serial_out(up, offset, value); + serial_in(up, UART_LCR); /* safe, no side-effects */ + break; + default: + serial_out(up, offset, value); + } +} + /* * We used to support using pause I/O for certain machines. We * haven't supported this for a while, but just in case it's badly @@ -1045,7 +1062,7 @@ static void autoconfig(struct uart_8250_port *up, unsigned int probeflags) #endif serial_outp(up, UART_MCR, save_mcr); serial8250_clear_fifos(up); - (void)serial_in(up, UART_RX); + serial_in(up, UART_RX); if (up->capabilities & UART_CAP_UUE) serial_outp(up, UART_IER, UART_IER_UUE); else @@ -1451,6 +1468,12 @@ static void serial_unlink_irq_chain(struct uart_8250_port *up) serial_do_unlink(i, up); } +/* Base timer interval for polling */ +static inline int poll_timeout(int timeout) +{ + return timeout > 6 ? (timeout / 2 - 2) : 1; +} + /* * This function is used to handle ports that do not have an * interrupt. This doesn't work very well for 16450's, but gives @@ -1460,16 +1483,51 @@ static void serial_unlink_irq_chain(struct uart_8250_port *up) static void serial8250_timeout(unsigned long data) { struct uart_8250_port *up = (struct uart_8250_port *)data; - unsigned int timeout; unsigned int iir; iir = serial_in(up, UART_IIR); if (!(iir & UART_IIR_NO_INT)) serial8250_handle_port(up); + mod_timer(&up->timer, jiffies + poll_timeout(up->port.timeout)); +} + +static void serial8250_backup_timeout(unsigned long data) +{ + struct uart_8250_port *up = (struct uart_8250_port *)data; + unsigned int iir, ier = 0; + + /* + * Must disable interrupts or else we risk racing with the interrupt + * based handler. + */ + if (is_real_interrupt(up->port.irq)) { + ier = serial_in(up, UART_IER); + serial_out(up, UART_IER, 0); + } - timeout = up->port.timeout; - timeout = timeout > 6 ? (timeout / 2 - 2) : 1; - mod_timer(&up->timer, jiffies + timeout); + iir = serial_in(up, UART_IIR); + + /* + * This should be a safe test for anyone who doesn't trust the + * IIR bits on their UART, but it's specifically designed for + * the "Diva" UART used on the management processor on many HP + * ia64 and parisc boxes. + */ + if ((iir & UART_IIR_NO_INT) && (up->ier & UART_IER_THRI) && + (!uart_circ_empty(&up->port.info->xmit) || up->port.x_char) && + (serial_in(up, UART_LSR) & UART_LSR_THRE)) { + iir &= ~(UART_IIR_ID | UART_IIR_NO_INT); + iir |= UART_IIR_THRI; + } + + if (!(iir & UART_IIR_NO_INT)) + serial8250_handle_port(up); + + if (is_real_interrupt(up->port.irq)) + serial_out(up, UART_IER, ier); + + /* Standard timer interval plus 0.2s to keep the port running */ + mod_timer(&up->timer, jiffies + poll_timeout(up->port.timeout) + HZ/5); } static unsigned int serial8250_tx_empty(struct uart_port *port) @@ -1540,6 +1598,37 @@ static void serial8250_break_ctl(struct uart_port *port, int break_state) spin_unlock_irqrestore(&up->port.lock, flags); } +#define BOTH_EMPTY (UART_LSR_TEMT | UART_LSR_THRE) + +/* + * Wait for transmitter & holding register to empty + */ +static inline void wait_for_xmitr(struct uart_8250_port *up, int bits) +{ + unsigned int status, tmout = 10000; + + /* Wait up to 10ms for the character(s) to be sent. */ + do { + status = serial_in(up, UART_LSR); + + if (status & UART_LSR_BI) + up->lsr_break_flag = UART_LSR_BI; + + if (--tmout == 0) + break; + udelay(1); + } while ((status & bits) != bits); + + /* Wait up to 1s for flow control if necessary */ + if (up->port.flags & UPF_CONS_FLOW) { + tmout = 1000000; + while (!(serial_in(up, UART_MSR) & UART_MSR_CTS) && --tmout) { + udelay(1); + touch_nmi_watchdog(); + } + } +} + static int serial8250_startup(struct uart_port *port) { struct uart_8250_port *up = (struct uart_8250_port *)port; @@ -1613,18 +1702,50 @@ static int serial8250_startup(struct uart_port *port) serial_outp(up, UART_LCR, 0); } + if (is_real_interrupt(up->port.irq)) { + /* + * Test for UARTs that do not reassert THRE when the + * transmitter is idle and the interrupt has already + * been cleared. Real 16550s should always reassert + * this interrupt whenever the transmitter is idle and + * the interrupt is enabled. Delays are necessary to + * allow register changes to become visible. + */ + spin_lock_irqsave(&up->port.lock, flags); + + wait_for_xmitr(up, UART_LSR_THRE); + serial_out_sync(up, UART_IER, UART_IER_THRI); + udelay(1); /* allow THRE to set */ + serial_in(up, UART_IIR); + serial_out(up, UART_IER, 0); + serial_out_sync(up, UART_IER, UART_IER_THRI); + udelay(1); /* allow a working UART time to re-assert THRE */ + iir = serial_in(up, UART_IIR); + serial_out(up, UART_IER, 0); + + spin_unlock_irqrestore(&up->port.lock, flags); + + /* + * If the interrupt is not reasserted, setup a timer to + * kick the UART on a regular basis. + */ + if (iir & UART_IIR_NO_INT) { + pr_debug("ttyS%d - using backup timer\n", port->line); + up->timer.function = serial8250_backup_timeout; + up->timer.data = (unsigned long)up; + mod_timer(&up->timer, jiffies + + poll_timeout(up->port.timeout) + HZ/5); + } + } + /* * If the "interrupt" for this port doesn't correspond with any * hardware interrupt, we use a timer-based system. The original * driver used to do this with IRQ0. */ if (!is_real_interrupt(up->port.irq)) { - unsigned int timeout = up->port.timeout; - - timeout = timeout > 6 ? (timeout / 2 - 2) : 1; - up->timer.data = (unsigned long)up; - mod_timer(&up->timer, jiffies + timeout); + mod_timer(&up->timer, jiffies + poll_timeout(up->port.timeout)); } else { retval = serial_link_irq_chain(up); if (retval) @@ -1740,9 +1861,9 @@ static void serial8250_shutdown(struct uart_port *port) */ (void) serial_in(up, UART_RX); - if (!is_real_interrupt(up->port.irq)) - del_timer_sync(&up->timer); - else + del_timer_sync(&up->timer); + up->timer.function = serial8250_timeout; + if (is_real_interrupt(up->port.irq)) serial_unlink_irq_chain(up); } @@ -2212,37 +2333,6 @@ serial8250_register_ports(struct uart_driver *drv, struct device *dev) #ifdef CONFIG_SERIAL_8250_CONSOLE -#define BOTH_EMPTY (UART_LSR_TEMT | UART_LSR_THRE) - -/* - * Wait for transmitter & holding register to empty - */ -static inline void wait_for_xmitr(struct uart_8250_port *up, int bits) -{ - unsigned int status, tmout = 10000; - - /* Wait up to 10ms for the character(s) to be sent. */ - do { - status = serial_in(up, UART_LSR); - - if (status & UART_LSR_BI) - up->lsr_break_flag = UART_LSR_BI; - - if (--tmout == 0) - break; - udelay(1); - } while ((status & bits) != bits); - - /* Wait up to 1s for flow control if necessary */ - if (up->port.flags & UPF_CONS_FLOW) { - tmout = 1000000; - while (!(serial_in(up, UART_MSR) & UART_MSR_CTS) && --tmout) { - udelay(1); - touch_nmi_watchdog(); - } - } -} - static void serial8250_console_putchar(struct uart_port *port, int ch) { struct uart_8250_port *up = (struct uart_8250_port *)port; |