diff options
Diffstat (limited to 'drivers/tty/serial/amba-pl011.c')
| -rw-r--r-- | drivers/tty/serial/amba-pl011.c | 88 |
1 files changed, 76 insertions, 12 deletions
diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c index cede93876649..d7e1edec50b5 100644 --- a/drivers/tty/serial/amba-pl011.c +++ b/drivers/tty/serial/amba-pl011.c @@ -1284,11 +1284,40 @@ static void pl011_break_ctl(struct uart_port *port, int break_state) } #ifdef CONFIG_CONSOLE_POLL + +static void pl011_quiesce_irqs(struct uart_port *port) +{ + struct uart_amba_port *uap = (struct uart_amba_port *)port; + unsigned char __iomem *regs = uap->port.membase; + + writew(readw(regs + UART011_MIS), regs + UART011_ICR); + /* + * There is no way to clear TXIM as this is "ready to transmit IRQ", so + * we simply mask it. start_tx() will unmask it. + * + * Note we can race with start_tx(), and if the race happens, the + * polling user might get another interrupt just after we clear it. + * But it should be OK and can happen even w/o the race, e.g. + * controller immediately got some new data and raised the IRQ. + * + * And whoever uses polling routines assumes that it manages the device + * (including tx queue), so we're also fine with start_tx()'s caller + * side. + */ + writew(readw(regs + UART011_IMSC) & ~UART011_TXIM, regs + UART011_IMSC); +} + static int pl011_get_poll_char(struct uart_port *port) { struct uart_amba_port *uap = (struct uart_amba_port *)port; unsigned int status; + /* + * The caller might need IRQs lowered, e.g. if used with KDB NMI + * debugger. + */ + pl011_quiesce_irqs(port); + status = readw(uap->port.membase + UART01x_FR); if (status & UART01x_FR_RXFE) return NO_POLL_CHAR; @@ -1309,10 +1338,9 @@ static void pl011_put_poll_char(struct uart_port *port, #endif /* CONFIG_CONSOLE_POLL */ -static int pl011_startup(struct uart_port *port) +static int pl011_hwinit(struct uart_port *port) { struct uart_amba_port *uap = (struct uart_amba_port *)port; - unsigned int cr; int retval; /* Optionaly enable pins to be muxed in and configured */ @@ -1337,6 +1365,37 @@ static int pl011_startup(struct uart_port *port) UART011_RTIS | UART011_RXIS, uap->port.membase + UART011_ICR); /* + * Save interrupts enable mask, and enable RX interrupts in case if + * the interrupt is used for NMI entry. + */ + uap->im = readw(uap->port.membase + UART011_IMSC); + writew(UART011_RTIM | UART011_RXIM, uap->port.membase + UART011_IMSC); + + if (uap->port.dev->platform_data) { + struct amba_pl011_data *plat; + + plat = uap->port.dev->platform_data; + if (plat->init) + plat->init(); + } + return 0; + out: + return retval; +} + +static int pl011_startup(struct uart_port *port) +{ + struct uart_amba_port *uap = (struct uart_amba_port *)port; + unsigned int cr; + int retval; + + retval = pl011_hwinit(port); + if (retval) + goto clk_dis; + + writew(uap->im, uap->port.membase + UART011_IMSC); + + /* * Allocate the IRQ */ retval = request_irq(uap->port.irq, pl011_int, 0, "uart-pl011", uap); @@ -1395,19 +1454,10 @@ static int pl011_startup(struct uart_port *port) writew(uap->im, uap->port.membase + UART011_IMSC); spin_unlock_irq(&uap->port.lock); - if (uap->port.dev->platform_data) { - struct amba_pl011_data *plat; - - plat = uap->port.dev->platform_data; - if (plat->init) - plat->init(); - } - return 0; clk_dis: clk_disable_unprepare(uap->clk); - out: return retval; } @@ -1595,13 +1645,26 @@ pl011_set_termios(struct uart_port *port, struct ktermios *termios, old_cr &= ~ST_UART011_CR_OVSFACT; } + /* + * Workaround for the ST Micro oversampling variants to + * increase the bitrate slightly, by lowering the divisor, + * to avoid delayed sampling of start bit at high speeds, + * else we see data corruption. + */ + if (uap->vendor->oversampling) { + if ((baud >= 3000000) && (baud < 3250000) && (quot > 1)) + quot -= 1; + else if ((baud > 3250000) && (quot > 2)) + quot -= 2; + } /* Set baud rate */ writew(quot & 0x3f, port->membase + UART011_FBRD); writew(quot >> 6, port->membase + UART011_IBRD); /* * ----------v----------v----------v----------v----- - * NOTE: MUST BE WRITTEN AFTER UARTLCR_M & UARTLCR_L + * NOTE: lcrh_tx and lcrh_rx MUST BE WRITTEN AFTER + * UART011_FBRD & UART011_IBRD. * ----------^----------^----------^----------^----- */ writew(lcr_h, port->membase + uap->lcrh_rx); @@ -1688,6 +1751,7 @@ static struct uart_ops amba_pl011_pops = { .config_port = pl011_config_port, .verify_port = pl011_verify_port, #ifdef CONFIG_CONSOLE_POLL + .poll_init = pl011_hwinit, .poll_get_char = pl011_get_poll_char, .poll_put_char = pl011_put_poll_char, #endif |