mirror of https://gitee.com/openkylin/linux.git
serial: 8250: Use hrtimers for rs485 delays
Previously the timers where based on the classic timers, giving a too coarse resolution on systems with configs of less than 1000 HZ. This patch changes the rs485 timers to hrtimers. Signed-off-by: Rafael Gago Castano <rgc@hms.se> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Rafael Gago
Greg Kroah-Hartman
parent
a6845e1e1b
commit
6e0a5de213
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@ -37,7 +37,7 @@
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#include <linux/slab.h>
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#include <linux/uaccess.h>
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#include <linux/pm_runtime.h>
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#include <linux/timer.h>
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#include <linux/ktime.h>
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#include <asm/io.h>
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#include <asm/irq.h>
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@ -553,8 +553,8 @@ static inline void serial8250_em485_rts_after_send(struct uart_8250_port *p)
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serial8250_out_MCR(p, mcr);
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}
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static void serial8250_em485_handle_start_tx(unsigned long arg);
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static void serial8250_em485_handle_stop_tx(unsigned long arg);
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static enum hrtimer_restart serial8250_em485_handle_start_tx(struct hrtimer *t);
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static enum hrtimer_restart serial8250_em485_handle_stop_tx(struct hrtimer *t);
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void serial8250_clear_and_reinit_fifos(struct uart_8250_port *p)
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{
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@ -609,12 +609,14 @@ int serial8250_em485_init(struct uart_8250_port *p)
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if (!p->em485)
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return -ENOMEM;
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setup_timer(&p->em485->stop_tx_timer,
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serial8250_em485_handle_stop_tx, (unsigned long)p);
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setup_timer(&p->em485->start_tx_timer,
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serial8250_em485_handle_start_tx, (unsigned long)p);
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hrtimer_init(&p->em485->stop_tx_timer, CLOCK_MONOTONIC,
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HRTIMER_MODE_REL);
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hrtimer_init(&p->em485->start_tx_timer, CLOCK_MONOTONIC,
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HRTIMER_MODE_REL);
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p->em485->stop_tx_timer.function = &serial8250_em485_handle_stop_tx;
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p->em485->start_tx_timer.function = &serial8250_em485_handle_start_tx;
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p->em485->port = p;
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p->em485->active_timer = NULL;
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serial8250_em485_rts_after_send(p);
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return 0;
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@ -639,8 +641,8 @@ void serial8250_em485_destroy(struct uart_8250_port *p)
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if (!p->em485)
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return;
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del_timer(&p->em485->start_tx_timer);
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del_timer(&p->em485->stop_tx_timer);
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hrtimer_cancel(&p->em485->start_tx_timer);
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hrtimer_cancel(&p->em485->stop_tx_timer);
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kfree(p->em485);
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p->em485 = NULL;
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@ -1435,12 +1437,13 @@ static void __do_stop_tx_rs485(struct uart_8250_port *p)
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serial_port_out(&p->port, UART_IER, p->ier);
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}
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}
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static void serial8250_em485_handle_stop_tx(unsigned long arg)
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static enum hrtimer_restart serial8250_em485_handle_stop_tx(struct hrtimer *t)
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{
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struct uart_8250_port *p = (struct uart_8250_port *)arg;
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struct uart_8250_em485 *em485 = p->em485;
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struct uart_8250_em485 *em485;
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struct uart_8250_port *p;
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unsigned long flags;
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em485 = container_of(t, struct uart_8250_em485, stop_tx_timer);
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p = em485->port;
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serial8250_rpm_get(p);
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spin_lock_irqsave(&p->port.lock, flags);
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@ -1451,6 +1454,16 @@ static void serial8250_em485_handle_stop_tx(unsigned long arg)
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}
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spin_unlock_irqrestore(&p->port.lock, flags);
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serial8250_rpm_put(p);
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return HRTIMER_NORESTART;
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}
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static void start_hrtimer_ms(struct hrtimer *hrt, unsigned long msec)
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{
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long sec = msec / 1000;
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long nsec = (msec % 1000) * 1000000;
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ktime_t t = ktime_set(sec, nsec);
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hrtimer_start(hrt, t, HRTIMER_MODE_REL);
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}
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static void __stop_tx_rs485(struct uart_8250_port *p)
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@ -1463,8 +1476,8 @@ static void __stop_tx_rs485(struct uart_8250_port *p)
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*/
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if (p->port.rs485.delay_rts_after_send > 0) {
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em485->active_timer = &em485->stop_tx_timer;
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mod_timer(&em485->stop_tx_timer, jiffies +
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p->port.rs485.delay_rts_after_send * HZ / 1000);
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start_hrtimer_ms(&em485->stop_tx_timer,
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p->port.rs485.delay_rts_after_send);
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} else {
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__do_stop_tx_rs485(p);
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}
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@ -1494,8 +1507,8 @@ static inline void __stop_tx(struct uart_8250_port *p)
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if ((lsr & BOTH_EMPTY) != BOTH_EMPTY)
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return;
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del_timer(&em485->start_tx_timer);
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em485->active_timer = NULL;
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hrtimer_cancel(&em485->start_tx_timer);
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__stop_tx_rs485(p);
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}
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@ -1558,8 +1571,9 @@ static inline void start_tx_rs485(struct uart_port *port)
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if (!(up->port.rs485.flags & SER_RS485_RX_DURING_TX))
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serial8250_stop_rx(&up->port);
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del_timer(&em485->stop_tx_timer);
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em485->active_timer = NULL;
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if (hrtimer_is_queued(&em485->stop_tx_timer))
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hrtimer_cancel(&em485->stop_tx_timer);
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mcr = serial8250_in_MCR(up);
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if (!!(up->port.rs485.flags & SER_RS485_RTS_ON_SEND) !=
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@ -1572,8 +1586,8 @@ static inline void start_tx_rs485(struct uart_port *port)
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if (up->port.rs485.delay_rts_before_send > 0) {
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em485->active_timer = &em485->start_tx_timer;
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mod_timer(&em485->start_tx_timer, jiffies +
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up->port.rs485.delay_rts_before_send * HZ / 1000);
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start_hrtimer_ms(&em485->start_tx_timer,
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up->port.rs485.delay_rts_before_send);
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return;
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}
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}
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@ -1581,11 +1595,13 @@ static inline void start_tx_rs485(struct uart_port *port)
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__start_tx(port);
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}
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static void serial8250_em485_handle_start_tx(unsigned long arg)
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static enum hrtimer_restart serial8250_em485_handle_start_tx(struct hrtimer *t)
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{
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struct uart_8250_port *p = (struct uart_8250_port *)arg;
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struct uart_8250_em485 *em485 = p->em485;
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struct uart_8250_em485 *em485;
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struct uart_8250_port *p;
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unsigned long flags;
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em485 = container_of(t, struct uart_8250_em485, start_tx_timer);
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p = em485->port;
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spin_lock_irqsave(&p->port.lock, flags);
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if (em485 &&
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@ -1594,6 +1610,7 @@ static void serial8250_em485_handle_start_tx(unsigned long arg)
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em485->active_timer = NULL;
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}
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spin_unlock_irqrestore(&p->port.lock, flags);
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return HRTIMER_NORESTART;
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}
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static void serial8250_start_tx(struct uart_port *port)
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@ -80,9 +80,10 @@ struct uart_8250_ops {
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};
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struct uart_8250_em485 {
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struct timer_list start_tx_timer; /* "rs485 start tx" timer */
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struct timer_list stop_tx_timer; /* "rs485 stop tx" timer */
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struct timer_list *active_timer; /* pointer to active timer */
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struct hrtimer start_tx_timer; /* "rs485 start tx" timer */
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struct hrtimer stop_tx_timer; /* "rs485 stop tx" timer */
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struct hrtimer *active_timer; /* pointer to active timer */
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struct uart_8250_port *port; /* for hrtimer callbacks */
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};
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/*
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