Messages in this thread | | | Date | Mon, 1 Mar 2010 13:51:15 +0300 | From | Alexander Gordeev <> | Subject | Re: [PATCHv2 5/6] pps: add parallel port PPS signal generator |
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On Mon, 1 Mar 2010 09:38:56 +0100 Rodolfo Giometti <giometti@enneenne.com> wrote:
> On Wed, Feb 24, 2010 at 03:28:16PM +0300, Alexander Gordeev wrote: > > Add PPS signal generator which utilizes STROBE pin of a parallel port to > > send PPS signals. It uses parport abstraction layer and hrtimers to > > precisely control the signal. > > > > Signed-off-by: Alexander Gordeev <lasaine@lvk.cs.msu.su> > > --- > > drivers/pps/Kconfig | 2 + > > drivers/pps/Makefile | 1 + > > drivers/pps/generators/Kconfig | 17 ++ > > drivers/pps/generators/Makefile | 9 + > > drivers/pps/generators/pps_gen_parport.c | 264 ++++++++++++++++++++++++++++++ > > 5 files changed, 293 insertions(+), 0 deletions(-) > > create mode 100644 drivers/pps/generators/Kconfig > > create mode 100644 drivers/pps/generators/Makefile > > create mode 100644 drivers/pps/generators/pps_gen_parport.c > > > > diff --git a/drivers/pps/Kconfig b/drivers/pps/Kconfig > > index 2bd4f65..f3b14cd 100644 > > --- a/drivers/pps/Kconfig > > +++ b/drivers/pps/Kconfig > > @@ -31,4 +31,6 @@ config PPS_DEBUG > > messages to the system log. Select this if you are having a > > problem with PPS support and want to see more of what is going on. > > > > +source drivers/pps/generators/Kconfig > > + > > endmenu > > diff --git a/drivers/pps/Makefile b/drivers/pps/Makefile > > index 19ea582..b299814 100644 > > --- a/drivers/pps/Makefile > > +++ b/drivers/pps/Makefile > > @@ -4,5 +4,6 @@ > > > > pps_core-y := pps.o kapi.o sysfs.o > > obj-$(CONFIG_PPS) := pps_core.o > > +obj-y += generators/ > > I suppose this patch doesn't apply on top of my latest PPS patchset, > does it? > > http://permalink.gmane.org/gmane.linux.kernel/954152 > > Generators support should be added after PPS clients one.
Sure, I'll swap the patches. I've noticed conflicts too when applying my patches on top of yours. Thanks!
> > > > ccflags-$(CONFIG_PPS_DEBUG) := -DDEBUG > > diff --git a/drivers/pps/generators/Kconfig b/drivers/pps/generators/Kconfig > > new file mode 100644 > > index 0000000..9cc1118 > > --- /dev/null > > +++ b/drivers/pps/generators/Kconfig > > @@ -0,0 +1,17 @@ > > +# > > +# PPS clients configuration > > +# > > s/clients/generators > > > + > > +if PPS > > + > > +comment "PPS generators support" > > + > > +config PPS_GENERATOR_PARPORT > > + tristate "Parallel port PPS signal generator" > > + depends on PARPORT != n && GENERIC_TIME > > + help > > + If you say yes here you get support for a PPS signal generator which > > + utilizes STROBE pin of a parallel port to send PPS signals. It uses > > + parport abstraction layer and hrtimers to precisely control the signal. > > + > > +endif > > diff --git a/drivers/pps/generators/Makefile b/drivers/pps/generators/Makefile > > new file mode 100644 > > index 0000000..303304a > > --- /dev/null > > +++ b/drivers/pps/generators/Makefile > > @@ -0,0 +1,9 @@ > > +# > > +# Makefile for PPS generators. > > +# > > + > > +obj-$(CONFIG_PPS_GENERATOR_PARPORT) += pps_gen_parport.o > > + > > +ifeq ($(CONFIG_PPS_DEBUG),y) > > +EXTRA_CFLAGS += -DDEBUG > > +endif > > diff --git a/drivers/pps/generators/pps_gen_parport.c b/drivers/pps/generators/pps_gen_parport.c > > new file mode 100644 > > index 0000000..e7cce30 > > --- /dev/null > > +++ b/drivers/pps/generators/pps_gen_parport.c > > @@ -0,0 +1,264 @@ > > +/* > > + * pps_gen_parport.c -- kernel parallel port PPS signal generator > > + * > > + * > > + * Copyright (C) 2009 Alexander Gordeev <lasaine@lvk.cs.msu.su> > > + * > > + * This program is free software; you can redistribute it and/or modify > > + * it under the terms of the GNU General Public License as published by > > + * the Free Software Foundation; either version 2 of the License, or > > + * (at your option) any later version. > > + * > > + * This program is distributed in the hope that it will be useful, > > + * but WITHOUT ANY WARRANTY; without even the implied warranty of > > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the > > + * GNU General Public License for more details. > > + * > > + * You should have received a copy of the GNU General Public License > > + * along with this program; if not, write to the Free Software > > + * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. > > + */ > > + > > + > > +/* > > + * TODO: > > + * 1. module parameters > > + * 2. check that local interrupts are blocked in hrtimer handler > > + * 3. fix issues when realtime clock is adjusted in a leap > > + * 4. test under heavy load > > + */ > > + > > +#include <linux/kernel.h> > > +#include <linux/module.h> > > +#include <linux/init.h> > > +#include <linux/time.h> > > +#include <linux/hrtimer.h> > > +#include <linux/parport.h> > > + > > +#define DRVNAME "pps_gen_parport" > > +#define DRVDESC "parallel port PPS signal generator" > > + > > +#define SIGNAL 0 > > +#define NO_SIGNAL PARPORT_CONTROL_STROBE > > + > > +#define SEND_DELAY 30000 /* delay between setting and > > + dropping the signal (ns) */ > > +#define SAFETY_INTERVAL 3000 /* set the hrtimer earlier for safety (ns) */ > > + > > +/* internal per port structure */ > > +struct pps_generator_pp { > > + struct pardevice *pardev; /* parport device */ > > + struct hrtimer timer; > > + long port_write_time; /* calibrated port write time (ns) */ > > +}; > > + > > +static struct pps_generator_pp device = { > > + .pardev = NULL, > > +}; > > + > > +static int attached; > > + > > +/* calibrated time between a hrtimer event and the reaction */ > > +static long hrtimer_error = SAFETY_INTERVAL; > > + > > +/* the kernel hrtimer event */ > > +static enum hrtimer_restart hrtimer_event(struct hrtimer *timer) > > +{ > > + struct timespec expire_time, ts1, ts2, ts3, dts; > > + struct pps_generator_pp *dev; > > + struct parport *port; > > + long lim, delta; > > + unsigned long flags; > > + > > + /* NB: approx time with blocked interrupts = > > + SEND_DELAY + 3 * SAFETY_INTERVAL */ > > + local_irq_save(flags); > > + > > + /* first of all we get the time stamp... */ > > + getnstimeofday(&ts1); > > + expire_time = ktime_to_timespec(timer->_expires); > > + dev = container_of(timer, struct pps_generator_pp, timer); > > + lim = NSEC_PER_SEC - SEND_DELAY - dev->port_write_time; > > + > > + /* check if we are late */ > > + if (expire_time.tv_sec != ts1.tv_sec || ts1.tv_nsec > lim) { > > + local_irq_restore(flags); > > + pr_err(DRVNAME ": we are late this time %ld.%09ld\n", > > + ts1.tv_sec, ts1.tv_nsec); > > + goto done; > > + } > > + > > + /* busy loop until the time is right for an assert edge */ > > + do { > > + getnstimeofday(&ts2); > > + } while (expire_time.tv_sec == ts2.tv_sec && ts2.tv_nsec < lim); > > + > > + /* set the signal */ > > + port = dev->pardev->port; > > + port->ops->write_control(port, SIGNAL); > > + > > + /* busy loop until the time is right for a clear edge */ > > + lim = NSEC_PER_SEC - dev->port_write_time; > > + do { > > + getnstimeofday(&ts2); > > + } while (expire_time.tv_sec == ts2.tv_sec && ts2.tv_nsec < lim); > > + > > + /* unset the signal */ > > + port->ops->write_control(port, NO_SIGNAL); > > + > > + getnstimeofday(&ts3); > > + > > + local_irq_restore(flags); > > + > > + /* update calibrated port write time */ > > + dts = timespec_sub(ts3, ts2); > > + dev->port_write_time = > > + (dev->port_write_time + timespec_to_ns(&dts)) >> 1; > > + > > +done: > > + /* update calibrated hrtimer error */ > > + dts = timespec_sub(ts1, expire_time); > > + delta = timespec_to_ns(&dts); > > + /* If the new error value is bigger then the old, use the new > > + * value, if not then slowly move towards the new value. This > > + * way it should be safe in bad conditions and efficient in > > + * good conditions. > > + */ > > + if (delta >= hrtimer_error) > > + hrtimer_error = delta; > > + else > > + hrtimer_error = (3 * hrtimer_error + delta) >> 2; > > + > > + /* update the hrtimer expire time */ > > + hrtimer_set_expires(timer, > > + ktime_set(expire_time.tv_sec + 1, > > + NSEC_PER_SEC - (SEND_DELAY + > > + dev->port_write_time + SAFETY_INTERVAL + > > + 2 * hrtimer_error))); > > + > > + return HRTIMER_RESTART; > > +} > > + > > +/* calibrate port write time */ > > +#define PORT_NTESTS_SHIFT 5 > > +static void calibrate_port(struct pps_generator_pp *dev) > > +{ > > + struct parport *port = dev->pardev->port; > > + int i; > > + long acc = 0; > > + > > + for (i = 0; i < (1 << PORT_NTESTS_SHIFT); i++) { > > + struct timespec a, b; > > + unsigned long irq_flags; > > + > > + local_irq_save(irq_flags); > > + getnstimeofday(&a); > > + port->ops->write_control(port, NO_SIGNAL); > > + getnstimeofday(&b); > > + local_irq_restore(irq_flags); > > + > > + b = timespec_sub(b, a); > > + acc += timespec_to_ns(&b); > > + } > > + > > + dev->port_write_time = acc >> PORT_NTESTS_SHIFT; > > + pr_info(DRVNAME ": port write takes %ldns\n", dev->port_write_time); > > +} > > + > > +static inline ktime_t next_intr_time(struct pps_generator_pp *dev) > > +{ > > + struct timespec ts; > > + > > + getnstimeofday(&ts); > > + > > + return ktime_set(ts.tv_sec + > > + ((ts.tv_nsec > 990 * NSEC_PER_MSEC) ? 1 : 0), > > + NSEC_PER_SEC - (SEND_DELAY + > > + dev->port_write_time + 3 * SAFETY_INTERVAL)); > > +} > > + > > +static void parport_attach(struct parport *port) > > +{ > > + if (attached) { > > + /* we already have a port */ > > + return; > > + } > > + > > + device.pardev = parport_register_device(port, DRVNAME, > > + NULL, NULL, NULL, 0, &device); > > + if (!device.pardev) { > > + pr_err(DRVNAME ": couldn't register with %s\n", port->name); > > + return; > > + } > > + > > + if (parport_claim_or_block(device.pardev) < 0) { > > + pr_err(DRVNAME ": couldn't claim %s\n", port->name); > > + goto err_unregister_dev; > > + } > > + > > + pr_info(DRVNAME ": attached to %s\n", port->name); > > + attached = 1; > > + > > + calibrate_port(&device); > > + > > + hrtimer_init(&device.timer, CLOCK_REALTIME, HRTIMER_MODE_ABS); > > + device.timer.function = hrtimer_event; > > +#ifdef CONFIG_PREEMPT_RT > > + /* hrtimer interrupt will run in the interrupt context with this */ > > + device.timer.irqsafe = 1; > > +#endif > > + > > + hrtimer_start(&device.timer, next_intr_time(&device), HRTIMER_MODE_ABS); > > + > > + return; > > + > > +err_unregister_dev: > > + parport_unregister_device(device.pardev); > > +} > > + > > +static void parport_detach(struct parport *port) > > +{ > > + if (port->cad != device.pardev) > > + /* not our port */ > > + return; > > Please use: > > if (port->cad != device.pardev) > return; /* not our port */
OK.
-- Alexander [unhandled content-type:application/pgp-signature] | |