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@xxxxxx>
---
drivers/tty/serial/8250/8250_port.c | 63 +++++++++++++++++++++++--------------
include/linux/serial_8250.h | 7 +++--
2 files changed, 44 insertions(+), 26 deletions(-)
diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
index a5fe0e6..463ae07 100644
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -37,7 +37,7 @@
#include <linux/slab.h>
#include <linux/uaccess.h>
#include <linux/pm_runtime.h>
-#include <linux/timer.h>
+#include <linux/ktime.h>
#include <asm/io.h>
#include <asm/irq.h>
@@ -553,8 +553,8 @@ static inline void serial8250_em485_rts_after_send(struct uart_8250_port *p)
serial8250_out_MCR(p, mcr);
}
-static void serial8250_em485_handle_start_tx(unsigned long arg);
-static void serial8250_em485_handle_stop_tx(unsigned long arg);
+static enum hrtimer_restart serial8250_em485_handle_start_tx(struct hrtimer *t);
+static enum hrtimer_restart serial8250_em485_handle_stop_tx(struct hrtimer *t);
void serial8250_clear_and_reinit_fifos(struct uart_8250_port *p)
{
@@ -609,12 +609,14 @@ int serial8250_em485_init(struct uart_8250_port *p)
if (!p->em485)
return -ENOMEM;
- setup_timer(&p->em485->stop_tx_timer,
- serial8250_em485_handle_stop_tx, (unsigned long)p);
- setup_timer(&p->em485->start_tx_timer,
- serial8250_em485_handle_start_tx, (unsigned long)p);
+ hrtimer_init(&p->em485->stop_tx_timer, CLOCK_MONOTONIC,
+ HRTIMER_MODE_REL);
+ hrtimer_init(&p->em485->start_tx_timer, CLOCK_MONOTONIC,
+ HRTIMER_MODE_REL);
+ p->em485->stop_tx_timer.function = &serial8250_em485_handle_stop_tx;
+ 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);
return 0;
@@ -639,8 +641,8 @@ void serial8250_em485_destroy(struct uart_8250_port *p)
if (!p->em485)
return;
- del_timer(&p->em485->start_tx_timer);
- del_timer(&p->em485->stop_tx_timer);
+ hrtimer_cancel(&p->em485->start_tx_timer);
+ hrtimer_cancel(&p->em485->stop_tx_timer);
kfree(p->em485);
p->em485 = NULL;
@@ -1435,12 +1437,13 @@ static void __do_stop_tx_rs485(struct uart_8250_port *p)
serial_port_out(&p->port, UART_IER, p->ier);
}
}
-
-static void serial8250_em485_handle_stop_tx(unsigned long arg)
+static enum hrtimer_restart serial8250_em485_handle_stop_tx(struct hrtimer *t)
{
- struct uart_8250_port *p = (struct uart_8250_port *)arg;
- struct uart_8250_em485 *em485 = p->em485;
+ struct uart_8250_em485 *em485;
+ struct uart_8250_port *p;
unsigned long flags;
+ em485 = container_of(t, struct uart_8250_em485, stop_tx_timer);
+ p = em485->port;
serial8250_rpm_get(p);
spin_lock_irqsave(&p->port.lock, flags);
@@ -1451,6 +1454,16 @@ static void serial8250_em485_handle_stop_tx(unsigned long arg)
}
spin_unlock_irqrestore(&p->port.lock, flags);
serial8250_rpm_put(p);
+ return HRTIMER_NORESTART;
+}
+
+static void start_hrtimer_ms(struct hrtimer *hrt, unsigned long msec)
+{
+ long sec = msec / 1000;
+ long nsec = (msec % 1000) * 1000000;
+ ktime_t t = ktime_set(sec, nsec);
+
+ hrtimer_start(hrt, t, HRTIMER_MODE_REL);
}
static void __stop_tx_rs485(struct uart_8250_port *p)
@@ -1463,8 +1476,8 @@ static void __stop_tx_rs485(struct uart_8250_port *p)
*/
if (p->port.rs485.delay_rts_after_send > 0) {
em485->active_timer = &em485->stop_tx_timer;
- mod_timer(&em485->stop_tx_timer, jiffies +
- p->port.rs485.delay_rts_after_send * HZ / 1000);
+ start_hrtimer_ms(&em485->stop_tx_timer,
+ p->port.rs485.delay_rts_after_send);
} else {
__do_stop_tx_rs485(p);
}
@@ -1494,8 +1507,8 @@ static inline void __stop_tx(struct uart_8250_port *p)
if ((lsr & BOTH_EMPTY) != BOTH_EMPTY)
return;
- del_timer(&em485->start_tx_timer);
em485->active_timer = NULL;
+ hrtimer_cancel(&em485->start_tx_timer);
__stop_tx_rs485(p);
}
@@ -1558,8 +1571,9 @@ static inline void start_tx_rs485(struct uart_port *port)
if (!(up->port.rs485.flags & SER_RS485_RX_DURING_TX))
serial8250_stop_rx(&up->port);
- del_timer(&em485->stop_tx_timer);
em485->active_timer = NULL;
+ if (hrtimer_is_queued(&em485->stop_tx_timer))
+ hrtimer_cancel(&em485->stop_tx_timer);
mcr = serial8250_in_MCR(up);
if (!!(up->port.rs485.flags & SER_RS485_RTS_ON_SEND) !=
@@ -1572,8 +1586,8 @@ static inline void start_tx_rs485(struct uart_port *port)
if (up->port.rs485.delay_rts_before_send > 0) {
em485->active_timer = &em485->start_tx_timer;
- mod_timer(&em485->start_tx_timer, jiffies +
- up->port.rs485.delay_rts_before_send * HZ / 1000);
+ start_hrtimer_ms(&em485->start_tx_timer,
+ up->port.rs485.delay_rts_before_send);
return;
}
}
@@ -1581,11 +1595,13 @@ static inline void start_tx_rs485(struct uart_port *port)
__start_tx(port);
}
-static void serial8250_em485_handle_start_tx(unsigned long arg)
+static enum hrtimer_restart serial8250_em485_handle_start_tx(struct hrtimer *t)
{
- struct uart_8250_port *p = (struct uart_8250_port *)arg;
- struct uart_8250_em485 *em485 = p->em485;
+ struct uart_8250_em485 *em485;
+ struct uart_8250_port *p;
unsigned long flags;
+ em485 = container_of(t, struct uart_8250_em485, start_tx_timer);
+ p = em485->port;
spin_lock_irqsave(&p->port.lock, flags);
if (em485 &&
@@ -1594,6 +1610,7 @@ static void serial8250_em485_handle_start_tx(unsigned long arg)
em485->active_timer = NULL;
}
spin_unlock_irqrestore(&p->port.lock, flags);
+ return HRTIMER_NORESTART;
}
static void serial8250_start_tx(struct uart_port *port)
diff --git a/include/linux/serial_8250.h b/include/linux/serial_8250.h
index 61fbb44..a27ef5f 100644
--- a/include/linux/serial_8250.h
+++ b/include/linux/serial_8250.h
@@ -80,9 +80,10 @@ struct uart_8250_ops {
};
struct uart_8250_em485 {
- struct timer_list start_tx_timer; /* "rs485 start tx" timer */
- struct timer_list stop_tx_timer; /* "rs485 stop tx" timer */
- struct timer_list *active_timer; /* pointer to active timer */
+ struct hrtimer start_tx_timer; /* "rs485 start tx" timer */
+ struct hrtimer stop_tx_timer; /* "rs485 stop tx" timer */
+ struct hrtimer *active_timer; /* pointer to active timer */
+ struct uart_8250_port *port; /* for hrtimer callbacks */
};
/*
--
2.7.4
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