diff options
Diffstat (limited to 'drivers/tty/serial/8250/8250_port.c')
| -rw-r--r-- | drivers/tty/serial/8250/8250_port.c | 238 |
1 files changed, 180 insertions, 58 deletions
diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c index 0325f2e53b74..f77bf820b7a3 100644 --- a/drivers/tty/serial/8250/8250_port.c +++ b/drivers/tty/serial/8250/8250_port.c @@ -557,17 +557,6 @@ static void serial8250_clear_fifos(struct uart_8250_port *p) } } -static inline void serial8250_em485_rts_after_send(struct uart_8250_port *p) -{ - unsigned char mcr = serial8250_in_MCR(p); - - if (p->port.rs485.flags & SER_RS485_RTS_AFTER_SEND) - mcr |= UART_MCR_RTS; - else - mcr &= ~UART_MCR_RTS; - serial8250_out_MCR(p, mcr); -} - static enum hrtimer_restart serial8250_em485_handle_start_tx(struct hrtimer *t); static enum hrtimer_restart serial8250_em485_handle_stop_tx(struct hrtimer *t); @@ -615,7 +604,7 @@ EXPORT_SYMBOL_GPL(serial8250_rpm_put); * * Return 0 - success, -errno - otherwise */ -int serial8250_em485_init(struct uart_8250_port *p) +static int serial8250_em485_init(struct uart_8250_port *p) { if (p->em485) return 0; @@ -632,11 +621,12 @@ int serial8250_em485_init(struct uart_8250_port *p) p->em485->start_tx_timer.function = &serial8250_em485_handle_start_tx; p->em485->port = p; p->em485->active_timer = NULL; - serial8250_em485_rts_after_send(p); + p->em485->tx_stopped = true; + + p->rs485_stop_tx(p); return 0; } -EXPORT_SYMBOL_GPL(serial8250_em485_init); /** * serial8250_em485_destroy() - put uart_8250_port into normal state @@ -664,6 +654,52 @@ void serial8250_em485_destroy(struct uart_8250_port *p) } EXPORT_SYMBOL_GPL(serial8250_em485_destroy); +/** + * serial8250_em485_config() - generic ->rs485_config() callback + * @port: uart port + * @rs485: rs485 settings + * + * Generic callback usable by 8250 uart drivers to activate rs485 settings + * if the uart is incapable of driving RTS as a Transmit Enable signal in + * hardware, relying on software emulation instead. + */ +int serial8250_em485_config(struct uart_port *port, struct serial_rs485 *rs485) +{ + struct uart_8250_port *up = up_to_u8250p(port); + + /* pick sane settings if the user hasn't */ + if (!!(rs485->flags & SER_RS485_RTS_ON_SEND) == + !!(rs485->flags & SER_RS485_RTS_AFTER_SEND)) { + rs485->flags |= SER_RS485_RTS_ON_SEND; + rs485->flags &= ~SER_RS485_RTS_AFTER_SEND; + } + + /* clamp the delays to [0, 100ms] */ + rs485->delay_rts_before_send = min(rs485->delay_rts_before_send, 100U); + rs485->delay_rts_after_send = min(rs485->delay_rts_after_send, 100U); + + memset(rs485->padding, 0, sizeof(rs485->padding)); + port->rs485 = *rs485; + + /* + * Both serial8250_em485_init() and serial8250_em485_destroy() + * are idempotent. + */ + if (rs485->flags & SER_RS485_ENABLED) { + int ret = serial8250_em485_init(up); + + if (ret) { + rs485->flags &= ~SER_RS485_ENABLED; + port->rs485.flags &= ~SER_RS485_ENABLED; + } + return ret; + } + + serial8250_em485_destroy(up); + return 0; +} +EXPORT_SYMBOL_GPL(serial8250_em485_config); + /* * These two wrappers ensure that enable_runtime_pm_tx() can be called more than * once and disable_runtime_pm_tx() will still disable RPM because the fifo is @@ -1318,8 +1354,8 @@ out_lock: fintek_8250_probe(up); if (up->capabilities != old_capabilities) { - pr_warn("%s: detected caps %08x should be %08x\n", - port->name, old_capabilities, up->capabilities); + dev_warn(port->dev, "detected caps %08x should be %08x\n", + old_capabilities, up->capabilities); } out: DEBUG_AUTOCONF("iir=%d ", scratch); @@ -1394,9 +1430,21 @@ static void serial8250_stop_rx(struct uart_port *port) serial8250_rpm_put(up); } -static void __do_stop_tx_rs485(struct uart_8250_port *p) +/** + * serial8250_em485_stop_tx() - generic ->rs485_stop_tx() callback + * @up: uart 8250 port + * + * Generic callback usable by 8250 uart drivers to stop rs485 transmission. + */ +void serial8250_em485_stop_tx(struct uart_8250_port *p) { - serial8250_em485_rts_after_send(p); + unsigned char mcr = serial8250_in_MCR(p); + + if (p->port.rs485.flags & SER_RS485_RTS_AFTER_SEND) + mcr |= UART_MCR_RTS; + else + mcr &= ~UART_MCR_RTS; + serial8250_out_MCR(p, mcr); /* * Empty the RX FIFO, we are not interested in anything @@ -1410,6 +1458,8 @@ static void __do_stop_tx_rs485(struct uart_8250_port *p) serial_port_out(&p->port, UART_IER, p->ier); } } +EXPORT_SYMBOL_GPL(serial8250_em485_stop_tx); + static enum hrtimer_restart serial8250_em485_handle_stop_tx(struct hrtimer *t) { struct uart_8250_em485 *em485; @@ -1422,8 +1472,9 @@ static enum hrtimer_restart serial8250_em485_handle_stop_tx(struct hrtimer *t) serial8250_rpm_get(p); spin_lock_irqsave(&p->port.lock, flags); if (em485->active_timer == &em485->stop_tx_timer) { - __do_stop_tx_rs485(p); + p->rs485_stop_tx(p); em485->active_timer = NULL; + em485->tx_stopped = true; } spin_unlock_irqrestore(&p->port.lock, flags); serial8250_rpm_put(p); @@ -1444,7 +1495,7 @@ static void __stop_tx_rs485(struct uart_8250_port *p) struct uart_8250_em485 *em485 = p->em485; /* - * __do_stop_tx_rs485 is going to set RTS according to config + * rs485_stop_tx() is going to set RTS according to config * AND flush RX FIFO if required. */ if (p->port.rs485.delay_rts_after_send > 0) { @@ -1452,7 +1503,9 @@ static void __stop_tx_rs485(struct uart_8250_port *p) start_hrtimer_ms(&em485->stop_tx_timer, p->port.rs485.delay_rts_after_send); } else { - __do_stop_tx_rs485(p); + p->rs485_stop_tx(p); + em485->active_timer = NULL; + em485->tx_stopped = true; } } @@ -1477,8 +1530,6 @@ static inline void __stop_tx(struct uart_8250_port *p) if ((lsr & BOTH_EMPTY) != BOTH_EMPTY) return; - em485->active_timer = NULL; - __stop_tx_rs485(p); } __do_stop_tx(p); @@ -1528,25 +1579,42 @@ static inline void __start_tx(struct uart_port *port) } } -static inline void start_tx_rs485(struct uart_port *port) +/** + * serial8250_em485_start_tx() - generic ->rs485_start_tx() callback + * @up: uart 8250 port + * + * Generic callback usable by 8250 uart drivers to start rs485 transmission. + * Assumes that setting the RTS bit in the MCR register means RTS is high. + * (Some chips use inverse semantics.) Further assumes that reception is + * stoppable by disabling the UART_IER_RDI interrupt. (Some chips set the + * UART_LSR_DR bit even when UART_IER_RDI is disabled, foiling this approach.) + */ +void serial8250_em485_start_tx(struct uart_8250_port *up) { - struct uart_8250_port *up = up_to_u8250p(port); - struct uart_8250_em485 *em485 = up->em485; - unsigned char mcr; + unsigned char mcr = serial8250_in_MCR(up); if (!(up->port.rs485.flags & SER_RS485_RX_DURING_TX)) serial8250_stop_rx(&up->port); + if (up->port.rs485.flags & SER_RS485_RTS_ON_SEND) + mcr |= UART_MCR_RTS; + else + mcr &= ~UART_MCR_RTS; + serial8250_out_MCR(up, mcr); +} +EXPORT_SYMBOL_GPL(serial8250_em485_start_tx); + +static inline void start_tx_rs485(struct uart_port *port) +{ + struct uart_8250_port *up = up_to_u8250p(port); + struct uart_8250_em485 *em485 = up->em485; + em485->active_timer = NULL; - mcr = serial8250_in_MCR(up); - if (!!(up->port.rs485.flags & SER_RS485_RTS_ON_SEND) != - !!(mcr & UART_MCR_RTS)) { - if (up->port.rs485.flags & SER_RS485_RTS_ON_SEND) - mcr |= UART_MCR_RTS; - else - mcr &= ~UART_MCR_RTS; - serial8250_out_MCR(up, mcr); + if (em485->tx_stopped) { + em485->tx_stopped = false; + + up->rs485_start_tx(up); if (up->port.rs485.delay_rts_before_send > 0) { em485->active_timer = &em485->start_tx_timer; @@ -1683,7 +1751,7 @@ void serial8250_read_char(struct uart_8250_port *up, unsigned char lsr) lsr &= port->read_status_mask; if (lsr & UART_LSR_BI) { - pr_debug("%s: handling break\n", __func__); + dev_dbg(port->dev, "handling break\n"); flag = TTY_BREAK; } else if (lsr & UART_LSR_PE) flag = TTY_PARITY; @@ -1815,6 +1883,7 @@ int serial8250_handle_irq(struct uart_port *port, unsigned int iir) unsigned char status; unsigned long flags; struct uart_8250_port *up = up_to_u8250p(port); + bool skip_rx = false; if (iir & UART_IIR_NO_INT) return 0; @@ -1823,7 +1892,20 @@ int serial8250_handle_irq(struct uart_port *port, unsigned int iir) status = serial_port_in(port, UART_LSR); - if (status & (UART_LSR_DR | UART_LSR_BI)) { + /* + * If port is stopped and there are no error conditions in the + * FIFO, then don't drain the FIFO, as this may lead to TTY buffer + * overflow. Not servicing, RX FIFO would trigger auto HW flow + * control when FIFO occupancy reaches preset threshold, thus + * halting RX. This only works when auto HW flow control is + * available. + */ + if (!(status & (UART_LSR_FIFOE | UART_LSR_BRK_ERROR_BITS)) && + (port->status & (UPSTAT_AUTOCTS | UPSTAT_AUTORTS)) && + !(port->read_status_mask & UART_LSR_DR)) + skip_rx = true; + + if (status & (UART_LSR_DR | UART_LSR_BI) && !skip_rx) { if (!up->dma || handle_rx_dma(up, iir)) status = serial8250_rx_chars(up, status); } @@ -1924,6 +2006,13 @@ void serial8250_do_set_mctrl(struct uart_port *port, unsigned int mctrl) struct uart_8250_port *up = up_to_u8250p(port); unsigned char mcr; + if (port->rs485.flags & SER_RS485_ENABLED) { + if (serial8250_in_MCR(up) & UART_MCR_RTS) + mctrl |= TIOCM_RTS; + else + mctrl &= ~TIOCM_RTS; + } + mcr = serial8250_TIOCM_to_MCR(mctrl); mcr = (mcr & up->mcr_mask) | up->mcr_force | up->mcr; @@ -2134,7 +2223,7 @@ int serial8250_do_startup(struct uart_port *port) */ if (!(port->flags & UPF_BUGGY_UART) && (serial_port_in(port, UART_LSR) == 0xff)) { - pr_info_ratelimited("%s: LSR safety check engaged!\n", port->name); + dev_info_ratelimited(port->dev, "LSR safety check engaged!\n"); retval = -ENODEV; goto out; } @@ -2166,8 +2255,7 @@ int serial8250_do_startup(struct uart_port *port) (port->type == PORT_ALTR_16550_F128)) && (port->fifosize > 1)) { /* Bounds checking of TX threshold (valid 0 to fifosize-2) */ if ((up->tx_loadsz < 2) || (up->tx_loadsz > port->fifosize)) { - pr_err("%s TX FIFO Threshold errors, skipping\n", - port->name); + dev_err(port->dev, "TX FIFO Threshold errors, skipping\n"); } else { serial_port_out(port, UART_ALTR_AFR, UART_ALTR_EN_TXFIFO_LW); @@ -2268,8 +2356,7 @@ int serial8250_do_startup(struct uart_port *port) if (lsr & UART_LSR_TEMT && iir & UART_IIR_NO_INT) { if (!(up->bugs & UART_BUG_TXEN)) { up->bugs |= UART_BUG_TXEN; - pr_debug("%s - enabling bad tx status workarounds\n", - port->name); + dev_dbg(port->dev, "enabling bad tx status workarounds\n"); } } else { up->bugs &= ~UART_BUG_TXEN; @@ -2294,10 +2381,14 @@ dont_test_tx_en: * Request DMA channels for both RX and TX. */ if (up->dma) { - retval = serial8250_request_dma(up); - if (retval) { - pr_warn_ratelimited("%s - failed to request DMA\n", - port->name); + const char *msg = NULL; + + if (uart_console(port)) + msg = "forbid DMA for kernel console"; + else if (serial8250_request_dma(up)) + msg = "failed to request DMA"; + if (msg) { + dev_warn_ratelimited(port->dev, "%s\n", msg); up->dma = NULL; } } @@ -2880,7 +2971,7 @@ static int do_serial8250_get_rxtrig(struct tty_port *port) return rxtrig_bytes; } -static ssize_t serial8250_get_attr_rx_trig_bytes(struct device *dev, +static ssize_t rx_trig_bytes_show(struct device *dev, struct device_attribute *attr, char *buf) { struct tty_port *port = dev_get_drvdata(dev); @@ -2926,7 +3017,7 @@ static int do_serial8250_set_rxtrig(struct tty_port *port, unsigned char bytes) return ret; } -static ssize_t serial8250_set_attr_rx_trig_bytes(struct device *dev, +static ssize_t rx_trig_bytes_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count) { struct tty_port *port = dev_get_drvdata(dev); @@ -2947,18 +3038,16 @@ static ssize_t serial8250_set_attr_rx_trig_bytes(struct device *dev, return count; } -static DEVICE_ATTR(rx_trig_bytes, S_IRUSR | S_IWUSR | S_IRGRP, - serial8250_get_attr_rx_trig_bytes, - serial8250_set_attr_rx_trig_bytes); +static DEVICE_ATTR_RW(rx_trig_bytes); static struct attribute *serial8250_dev_attrs[] = { &dev_attr_rx_trig_bytes.attr, - NULL, - }; + NULL +}; static struct attribute_group serial8250_dev_attr_group = { .attrs = serial8250_dev_attrs, - }; +}; static void register_dev_spec_attr_grp(struct uart_8250_port *up) { @@ -2987,6 +3076,9 @@ static void serial8250_config_port(struct uart_port *port, int flags) if (flags & UART_CONFIG_TYPE) autoconfig(up); + if (port->rs485.flags & SER_RS485_ENABLED) + port->rs485_config(port, &port->rs485); + /* if access method is AU, it is a 16550 with a quirk */ if (port->type == PORT_16550A && port->iotype == UPIO_AU) up->bugs |= UART_BUG_NOMSR; @@ -3127,10 +3219,14 @@ static void serial8250_console_restore(struct uart_8250_port *up) * any possible real use of the port... * * The console_lock must be held when we get here. + * + * Doing runtime PM is really a bad idea for the kernel console. + * Thus, we assume the function is called when device is powered up. */ void serial8250_console_write(struct uart_8250_port *up, const char *s, unsigned int count) { + struct uart_8250_em485 *em485 = up->em485; struct uart_port *port = &up->port; unsigned long flags; unsigned int ier; @@ -3138,8 +3234,6 @@ void serial8250_console_write(struct uart_8250_port *up, const char *s, touch_nmi_watchdog(); - serial8250_rpm_get(up); - if (oops_in_progress) locked = spin_trylock_irqsave(&port->lock, flags); else @@ -3161,6 +3255,12 @@ void serial8250_console_write(struct uart_8250_port *up, const char *s, up->canary = 0; } + if (em485) { + if (em485->tx_stopped) + up->rs485_start_tx(up); + mdelay(port->rs485.delay_rts_before_send); + } + uart_console_write(port, s, count, serial8250_console_putchar); /* @@ -3168,6 +3268,13 @@ void serial8250_console_write(struct uart_8250_port *up, const char *s, * and restore the IER */ wait_for_xmitr(up, BOTH_EMPTY); + + if (em485) { + mdelay(port->rs485.delay_rts_after_send); + if (em485->tx_stopped) + up->rs485_stop_tx(up); + } + serial_port_out(port, UART_IER, ier); /* @@ -3182,7 +3289,6 @@ void serial8250_console_write(struct uart_8250_port *up, const char *s, if (locked) spin_unlock_irqrestore(&port->lock, flags); - serial8250_rpm_put(up); } static unsigned int probe_baud(struct uart_port *port) @@ -3206,6 +3312,7 @@ int serial8250_console_setup(struct uart_port *port, char *options, bool probe) int bits = 8; int parity = 'n'; int flow = 'n'; + int ret; if (!port->iobase && !port->membase) return -ENODEV; @@ -3215,7 +3322,22 @@ int serial8250_console_setup(struct uart_port *port, char *options, bool probe) else if (probe) baud = probe_baud(port); - return uart_set_options(port, port->cons, baud, parity, bits, flow); + ret = uart_set_options(port, port->cons, baud, parity, bits, flow); + if (ret) + return ret; + + if (port->dev) + pm_runtime_get_sync(port->dev); + + return 0; +} + +int serial8250_console_exit(struct uart_port *port) +{ + if (port->dev) + pm_runtime_put_sync(port->dev); + + return 0; } #endif /* CONFIG_SERIAL_8250_CONSOLE */ |