Message-ID: <20260123035607.22340-1-enelsonmoore@gmail.com>
Date: Thu, 22 Jan 2026 19:55:47 -0800
From: Ethan Nelson-Moore <enelsonmoore@...il.com>
To: linux-kernel@...r.kernel.org
Cc: Ethan Nelson-Moore <enelsonmoore@...il.com>,
	Rodolfo Giometti <giometti@...eenne.com>,
	Subramanian Mohan <subramanian.mohan@...el.com>,
	Lakshmi Sowjanya D <lakshmi.sowjanya.d@...el.com>,
	Pandith N <pandith.n@...el.com>,
	Thejesh Reddy T R <thejesh.reddy.t.r@...el.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Christopher Hall <christopher.s.hall@...el.com>,
	Nam Cao <namcao@...utronix.de>,
	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
	Zack Rusin <zack.rusin@...adcom.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Petr Mladek <pmladek@...e.com>
Subject: [PATCH] pps: generators: remove broken pps_gen_parport driver

This driver was introduced in January 2011 and has been marked
BROKEN for almost its entire existence, since commit 95b90afec301
("pps: make pps_gen_parport depend on BROKEN") in March 2011.
It is unlikely anyone will fix the driver at this point.

Signed-off-by: Ethan Nelson-Moore <enelsonmoore@...il.com>
---
 drivers/pps/generators/Kconfig           |   8 -
 drivers/pps/generators/Makefile          |   1 -
 drivers/pps/generators/pps_gen_parport.c | 238 -----------------------
 3 files changed, 247 deletions(-)
 delete mode 100644 drivers/pps/generators/pps_gen_parport.c

diff --git a/drivers/pps/generators/Kconfig b/drivers/pps/generators/Kconfig
index b3f340ed3163..4ef02b3f2576 100644
--- a/drivers/pps/generators/Kconfig
+++ b/drivers/pps/generators/Kconfig
@@ -23,14 +23,6 @@ config PPS_GENERATOR_DUMMY
           This driver can also be built as a module.  If so, the module
           will be called pps_gen-dummy.
 
-config PPS_GENERATOR_PARPORT
-	tristate "Parallel port PPS signal generator"
-	depends on PARPORT && BROKEN
-	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.
-
 config PPS_GENERATOR_TIO
 	tristate "TIO PPS signal generator"
 	depends on X86 && CPU_SUP_INTEL
diff --git a/drivers/pps/generators/Makefile b/drivers/pps/generators/Makefile
index e109920e8a2d..5d38774b4a56 100644
--- a/drivers/pps/generators/Makefile
+++ b/drivers/pps/generators/Makefile
@@ -7,7 +7,6 @@ pps_gen_core-y			:= pps_gen.o sysfs.o
 obj-$(CONFIG_PPS_GENERATOR)	:= pps_gen_core.o
 
 obj-$(CONFIG_PPS_GENERATOR_DUMMY)   += pps_gen-dummy.o
-obj-$(CONFIG_PPS_GENERATOR_PARPORT) += pps_gen_parport.o
 obj-$(CONFIG_PPS_GENERATOR_TIO)     += pps_gen_tio.o
 
 ccflags-$(CONFIG_PPS_DEBUG) := -DDEBUG
diff --git a/drivers/pps/generators/pps_gen_parport.c b/drivers/pps/generators/pps_gen_parport.c
deleted file mode 100644
index 05bbf8d30ef1..000000000000
--- a/drivers/pps/generators/pps_gen_parport.c
+++ /dev/null
@@ -1,238 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0-or-later
-/*
- * pps_gen_parport.c -- kernel parallel port PPS signal generator
- *
- * Copyright (C) 2009   Alexander Gordeev <lasaine@....cs.msu.su>
- */
-
-
-/*
- * TODO:
- * fix issues when realtime clock is adjusted in a leap
- */
-
-#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
-
-#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 SIGNAL		0
-#define NO_SIGNAL	PARPORT_CONTROL_STROBE
-
-/* module parameters */
-
-#define SEND_DELAY_MAX		100000
-
-static unsigned int send_delay = 30000;
-MODULE_PARM_DESC(delay,
-	"Delay between setting and dropping the signal (ns)");
-module_param_named(delay, send_delay, uint, 0);
-
-
-#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 timespec64 expire_time, ts1, ts2, ts3, dts;
-	struct pps_generator_pp *dev;
-	struct parport *port;
-	long lim, delta;
-	unsigned long flags;
-
-	/* We have to disable interrupts here. The idea is to prevent
-	 * other interrupts on the same processor to introduce random
-	 * lags while polling the clock. ktime_get_real_ts64() takes <1us on
-	 * most machines while other interrupt handlers can take much
-	 * more potentially.
-	 *
-	 * NB: approx time with blocked interrupts =
-	 * send_delay + 3 * SAFETY_INTERVAL
-	 */
-	local_irq_save(flags);
-
-	/* first of all we get the time stamp... */
-	ktime_get_real_ts64(&ts1);
-	expire_time = ktime_to_timespec64(hrtimer_get_softexpires(timer));
-	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("we are late this time %ptSp\n", &ts1);
-		goto done;
-	}
-
-	/* busy loop until the time is right for an assert edge */
-	do {
-		ktime_get_real_ts64(&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 {
-		ktime_get_real_ts64(&ts2);
-	} while (expire_time.tv_sec == ts2.tv_sec && ts2.tv_nsec < lim);
-
-	/* unset the signal */
-	port->ops->write_control(port, NO_SIGNAL);
-
-	ktime_get_real_ts64(&ts3);
-
-	local_irq_restore(flags);
-
-	/* update calibrated port write time */
-	dts = timespec64_sub(ts3, ts2);
-	dev->port_write_time =
-		(dev->port_write_time + timespec64_to_ns(&dts)) >> 1;
-
-done:
-	/* update calibrated hrtimer error */
-	dts = timespec64_sub(ts1, expire_time);
-	delta = timespec64_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 timespec64 a, b;
-		unsigned long irq_flags;
-
-		local_irq_save(irq_flags);
-		ktime_get_real_ts64(&a);
-		port->ops->write_control(port, NO_SIGNAL);
-		ktime_get_real_ts64(&b);
-		local_irq_restore(irq_flags);
-
-		b = timespec64_sub(b, a);
-		acc += timespec64_to_ns(&b);
-	}
-
-	dev->port_write_time = acc >> PORT_NTESTS_SHIFT;
-	pr_info("port write takes %ldns\n", dev->port_write_time);
-}
-
-static inline ktime_t next_intr_time(struct pps_generator_pp *dev)
-{
-	struct timespec64 ts;
-
-	ktime_get_real_ts64(&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)
-{
-	struct pardev_cb pps_cb;
-
-	if (send_delay > SEND_DELAY_MAX) {
-		pr_err("delay value should be not greater then %d\n", SEND_DELAY_MAX);
-		return;
-	}
-
-	if (attached) {
-		/* we already have a port */
-		return;
-	}
-
-	memset(&pps_cb, 0, sizeof(pps_cb));
-	pps_cb.private = &device;
-	pps_cb.flags = PARPORT_FLAG_EXCL;
-	device.pardev = parport_register_dev_model(port, KBUILD_MODNAME,
-						   &pps_cb, 0);
-	if (!device.pardev) {
-		pr_err("couldn't register with %s\n", port->name);
-		return;
-	}
-
-	if (parport_claim_or_block(device.pardev) < 0) {
-		pr_err("couldn't claim %s\n", port->name);
-		goto err_unregister_dev;
-	}
-
-	pr_info("attached to %s\n", port->name);
-	attached = 1;
-
-	calibrate_port(&device);
-
-	hrtimer_setup(&device.timer, hrtimer_event, CLOCK_REALTIME, HRTIMER_MODE_ABS);
-	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)
-		return;	/* not our port */
-
-	hrtimer_cancel(&device.timer);
-	parport_release(device.pardev);
-	parport_unregister_device(device.pardev);
-}
-
-static struct parport_driver pps_gen_parport_driver = {
-	.name = KBUILD_MODNAME,
-	.match_port = parport_attach,
-	.detach = parport_detach,
-};
-module_parport_driver(pps_gen_parport_driver);
-
-MODULE_AUTHOR("Alexander Gordeev <lasaine@....cs.msu.su>");
-MODULE_DESCRIPTION("parallel port PPS signal generator");
-MODULE_LICENSE("GPL");
-- 
2.43.0

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