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Message-Id: <1269340154-6533-1-git-send-email-chripell@fsfe.org>
Date: Tue, 23 Mar 2010 11:29:14 +0100
From: Christian Pellegrin <chripell@...e.org>
To: feng.tang@...el.com, akpm@...ux-foundation.org, greg@...ah.com,
david-b@...bell.net, grant.likely@...retlab.ca,
alan@...rguk.ukuu.org.uk, spi-devel-general@...ts.sourceforge.net,
linux-serial@...r.kernel.org, linux-kernel@...r.kernel.org
Cc: Christian Pellegrin <chripell@...e.org>
Subject: [PATCH v1 2/4] max3100: moved to threaded interrupt
The driver was reworked to use threaded interrupts instead of workqueus.
This is a major boost in performance because the former are scheduled as
SCHED_FIFO processes. As a side effect suspend/resume code was greatly
simplified.
Signed-off-by: Christian Pellegrin <chripell@...e.org>
---
drivers/serial/max3100.c | 102 ++++++++++++++-------------------------------
1 files changed, 32 insertions(+), 70 deletions(-)
diff --git a/drivers/serial/max3100.c b/drivers/serial/max3100.c
index 3c30c56..0c972c6 100644
--- a/drivers/serial/max3100.c
+++ b/drivers/serial/max3100.c
@@ -45,7 +45,9 @@
#include <linux/serial_core.h>
#include <linux/serial.h>
#include <linux/spi/spi.h>
-#include <linux/freezer.h>
+#include <linux/kthread.h>
+#include <linux/interrupt.h>
+#include <linux/bitops.h>
#include <linux/serial_max3100.h>
@@ -113,18 +115,15 @@ struct max3100_port {
int irq; /* irq assigned to the max3100 */
+ /* the workqueue is needed because we cannot schedule
+ a threaded interrupt during PM
+ */
+ struct work_struct resume_work;
+
int minor; /* minor number */
int crystal; /* 1 if 3.6864Mhz crystal 0 for 1.8432 */
int loopback; /* 1 if we are in loopback mode */
- /* for handling irqs: need workqueue since we do spi_sync */
- struct workqueue_struct *workqueue;
- struct work_struct work;
- /* set to 1 to make the workhandler exit as soon as possible */
- int force_end_work;
- /* need to know we are suspending to avoid deadlock on workqueue */
- int suspending;
-
/* hook for suspending MAX3100 via dedicated pin */
void (*max3100_hw_suspend) (int suspend);
@@ -171,13 +170,12 @@ static void max3100_calc_parity(struct max3100_port *s, u16 *c)
*c |= max3100_do_parity(s, *c) << 8;
}
-static void max3100_work(struct work_struct *w);
-
-static void max3100_dowork(struct max3100_port *s)
+static void max3100_resume_work(struct work_struct *w)
{
- if (!s->force_end_work && !work_pending(&s->work) &&
- !freezing(current) && !s->suspending)
- queue_work(s->workqueue, &s->work);
+ struct max3100_port *s = container_of(w, struct max3100_port,
+ resume_work);
+
+ raise_threaded_irq(s->irq);
}
static void max3100_timeout(unsigned long data)
@@ -185,7 +183,7 @@ static void max3100_timeout(unsigned long data)
struct max3100_port *s = (struct max3100_port *)data;
if (s->port.state) {
- max3100_dowork(s);
+ raise_threaded_irq(s->irq);
mod_timer(&s->timer, jiffies + s->poll_time);
}
}
@@ -255,9 +253,9 @@ static int max3100_handlerx(struct max3100_port *s, u16 rx)
return ret;
}
-static void max3100_work(struct work_struct *w)
+static irqreturn_t max3100_ist(int irq, void *dev_id)
{
- struct max3100_port *s = container_of(w, struct max3100_port, work);
+ struct max3100_port *s = dev_id;
int rxchars;
u16 tx, rx;
int conf, cconf, rts, crts;
@@ -314,23 +312,14 @@ static void max3100_work(struct work_struct *w)
if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
uart_write_wakeup(&s->port);
- } while (!s->force_end_work &&
- !freezing(current) &&
+ } while (!kthread_should_stop() &&
((rx & MAX3100_R) ||
(!uart_circ_empty(xmit) &&
!uart_tx_stopped(&s->port))));
if (rxchars > 0 && s->port.state->port.tty != NULL)
tty_flip_buffer_push(s->port.state->port.tty);
-}
-
-static irqreturn_t max3100_irq(int irqno, void *dev_id)
-{
- struct max3100_port *s = dev_id;
-
- dev_dbg(&s->spi->dev, "%s\n", __func__);
- max3100_dowork(s);
return IRQ_HANDLED;
}
@@ -353,7 +342,7 @@ static void max3100_start_tx(struct uart_port *port)
dev_dbg(&s->spi->dev, "%s\n", __func__);
- max3100_dowork(s);
+ raise_threaded_irq(s->irq);
}
static void max3100_stop_rx(struct uart_port *port)
@@ -369,7 +358,7 @@ static void max3100_stop_rx(struct uart_port *port)
s->conf &= ~MAX3100_RM;
s->conf_commit = 1;
spin_unlock(&s->conf_lock);
- max3100_dowork(s);
+ raise_threaded_irq(s->irq);
}
static unsigned int max3100_tx_empty(struct uart_port *port)
@@ -381,7 +370,7 @@ static unsigned int max3100_tx_empty(struct uart_port *port)
dev_dbg(&s->spi->dev, "%s\n", __func__);
/* may not be truly up-to-date */
- max3100_dowork(s);
+ raise_threaded_irq(s->irq);
return s->tx_empty;
}
@@ -394,7 +383,7 @@ static unsigned int max3100_get_mctrl(struct uart_port *port)
dev_dbg(&s->spi->dev, "%s\n", __func__);
/* may not be truly up-to-date */
- max3100_dowork(s);
+ raise_threaded_irq(s->irq);
/* always assert DCD and DSR since these lines are not wired */
return (s->cts ? TIOCM_CTS : 0) | TIOCM_DSR | TIOCM_CAR;
}
@@ -414,7 +403,7 @@ static void max3100_set_mctrl(struct uart_port *port, unsigned int mctrl)
if (s->rts != rts) {
s->rts = rts;
s->rts_commit = 1;
- max3100_dowork(s);
+ raise_threaded_irq(s->irq);
}
spin_unlock(&s->conf_lock);
}
@@ -528,7 +517,7 @@ max3100_set_termios(struct uart_port *port, struct ktermios *termios,
MAX3100_STATUS_PE | MAX3100_STATUS_FE |
MAX3100_STATUS_OE;
- /* we are sending char from a workqueue so enable */
+ /* we are sending char from a threded irq so enable */
s->port.state->port.tty->low_latency = 1;
if (s->poll_time > 0)
@@ -541,7 +530,7 @@ max3100_set_termios(struct uart_port *port, struct ktermios *termios,
s->conf_commit = 1;
s->parity = parity;
spin_unlock(&s->conf_lock);
- max3100_dowork(s);
+ raise_threaded_irq(s->irq);
if (UART_ENABLE_MS(&s->port, termios->c_cflag))
max3100_enable_ms(&s->port);
@@ -555,19 +544,11 @@ static void max3100_shutdown(struct uart_port *port)
dev_dbg(&s->spi->dev, "%s\n", __func__);
- if (s->suspending)
- return;
-
- s->force_end_work = 1;
-
if (s->poll_time > 0)
del_timer_sync(&s->timer);
- if (s->workqueue) {
- flush_workqueue(s->workqueue);
- destroy_workqueue(s->workqueue);
- s->workqueue = NULL;
- }
+ flush_work(&s->resume_work);
+
if (s->irq)
free_irq(s->irq, s);
@@ -587,7 +568,6 @@ static int max3100_startup(struct uart_port *port)
struct max3100_port *s = container_of(port,
struct max3100_port,
port);
- char b[12];
dev_dbg(&s->spi->dev, "%s\n", __func__);
@@ -595,27 +575,15 @@ static int max3100_startup(struct uart_port *port)
s->baud = s->crystal ? 230400 : 115200;
s->rx_enabled = 1;
- if (s->suspending)
- return 0;
-
- s->force_end_work = 0;
s->parity = 0;
s->rts = 0;
- sprintf(b, "max3100-%d", s->minor);
- s->workqueue = create_freezeable_workqueue(b);
- if (!s->workqueue) {
- dev_warn(&s->spi->dev, "cannot create workqueue\n");
- return -EBUSY;
- }
- INIT_WORK(&s->work, max3100_work);
+ INIT_WORK(&s->resume_work, max3100_resume_work);
- if (request_irq(s->irq, max3100_irq,
+ if (request_threaded_irq(s->irq, NULL, max3100_ist,
IRQF_TRIGGER_FALLING, "max3100", s) < 0) {
- dev_warn(&s->spi->dev, "cannot allocate irq %d\n", s->irq);
+ dev_err(&s->spi->dev, "cannot allocate irq %d\n", s->irq);
s->irq = 0;
- destroy_workqueue(s->workqueue);
- s->workqueue = NULL;
return -EBUSY;
}
@@ -628,7 +596,7 @@ static int max3100_startup(struct uart_port *port)
if (s->max3100_hw_suspend)
s->max3100_hw_suspend(0);
s->conf_commit = 1;
- max3100_dowork(s);
+ raise_threaded_irq(s->irq);
/* wait for clock to settle */
msleep(50);
@@ -857,9 +825,6 @@ static int max3100_suspend(struct spi_device *spi, pm_message_t state)
disable_irq(s->irq);
- s->suspending = 1;
- uart_suspend_port(&max3100_uart_driver, &s->port);
-
if (s->max3100_hw_suspend)
s->max3100_hw_suspend(1);
else {
@@ -880,14 +845,11 @@ static int max3100_resume(struct spi_device *spi)
if (s->max3100_hw_suspend)
s->max3100_hw_suspend(0);
- uart_resume_port(&max3100_uart_driver, &s->port);
- s->suspending = 0;
enable_irq(s->irq);
-
+ /* must reconfigure if power was cut-off the chip during suspend */
s->conf_commit = 1;
- if (s->workqueue)
- max3100_dowork(s);
+ schedule_work(&s->resume_work);
return 0;
}
--
1.5.6.5
--
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