[deliverable/linux.git] / drivers / pps / clients / pps_parport.c

/*
 * pps_parport.c -- kernel parallel port PPS client
 *
 *
 * 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:
 * implement echo over SEL pin
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/irqnr.h>
#include <linux/time.h>
#include <linux/parport.h>
#include <linux/pps_kernel.h>

#define DRVDESC "parallel port PPS client"

/* module parameters */

#define CLEAR_WAIT_MAX		100
#define CLEAR_WAIT_MAX_ERRORS	5

static unsigned int clear_wait = 100;
MODULE_PARM_DESC(clear_wait,
	"Maximum number of port reads when polling for signal clear,"
	" zero turns clear edge capture off entirely");
module_param(clear_wait, uint, 0);


/* internal per port structure */
struct pps_client_pp {
	struct pardevice *pardev;	/* parport device */
	struct pps_device *pps;		/* PPS device */
	unsigned int cw;		/* port clear timeout */
	unsigned int cw_err;		/* number of timeouts */
};

static inline int signal_is_set(struct parport *port)
{
	return (port->ops->read_status(port) & PARPORT_STATUS_ACK) != 0;
}

/* parport interrupt handler */
static void parport_irq(void *handle)
{
	struct pps_event_time ts_assert, ts_clear;
	struct pps_client_pp *dev = handle;
	struct parport *port = dev->pardev->port;
	unsigned int i;
	unsigned long flags;

	/* first of all we get the time stamp... */
	pps_get_ts(&ts_assert);

	if (dev->cw == 0)
		/* clear edge capture disabled */
		goto out_assert;

	/* try capture the clear edge */

	/* We have to disable interrupts here. The idea is to prevent
	 * other interrupts on the same processor to introduce random
	 * lags while polling the port. Reading from IO port is known
	 * to take approximately 1us while other interrupt handlers can
	 * take much more potentially.
	 *
	 * Interrupts won't be disabled for a long time because the
	 * number of polls is limited by clear_wait parameter which is
	 * kept rather low. So it should never be an issue.
	 */
	local_irq_save(flags);
	/* check the signal (no signal means the pulse is lost this time) */
	if (!signal_is_set(port)) {
		local_irq_restore(flags);
		dev_err(dev->pps->dev, "lost the signal\n");
		goto out_assert;
	}

	/* poll the port until the signal is unset */
	for (i = dev->cw; i; i--)
		if (!signal_is_set(port)) {
			pps_get_ts(&ts_clear);
			local_irq_restore(flags);
			dev->cw_err = 0;
			goto out_both;
		}
	local_irq_restore(flags);

	/* timeout */
	dev->cw_err++;
	if (dev->cw_err >= CLEAR_WAIT_MAX_ERRORS) {
		dev_err(dev->pps->dev, "disabled clear edge capture after %d"
				" timeouts\n", dev->cw_err);
		dev->cw = 0;
		dev->cw_err = 0;
	}

out_assert:
	/* fire assert event */
	pps_event(dev->pps, &ts_assert,
			PPS_CAPTUREASSERT, NULL);
	return;

out_both:
	/* fire assert event */
	pps_event(dev->pps, &ts_assert,
			PPS_CAPTUREASSERT, NULL);
	/* fire clear event */
	pps_event(dev->pps, &ts_clear,
			PPS_CAPTURECLEAR, NULL);
	return;
}

static void parport_attach(struct parport *port)
{
	struct pps_client_pp *device;
	struct pps_source_info info = {
		.name		= KBUILD_MODNAME,
		.path		= "",
		.mode		= PPS_CAPTUREBOTH | \
				  PPS_OFFSETASSERT | PPS_OFFSETCLEAR | \
				  PPS_ECHOASSERT | PPS_ECHOCLEAR | \
				  PPS_CANWAIT | PPS_TSFMT_TSPEC,
		.owner		= THIS_MODULE,
		.dev		= NULL
	};

	device = kzalloc(sizeof(struct pps_client_pp), GFP_KERNEL);
	if (!device) {
		pr_err("memory allocation failed, not attaching\n");
		return;
	}

	device->pardev = parport_register_device(port, KBUILD_MODNAME,
			NULL, NULL, parport_irq, PARPORT_FLAG_EXCL, device);
	if (!device->pardev) {
		pr_err("couldn't register with %s\n", port->name);
		goto err_free;
	}

	if (parport_claim_or_block(device->pardev) < 0) {
		pr_err("couldn't claim %s\n", port->name);
		goto err_unregister_dev;
	}

	device->pps = pps_register_source(&info,
			PPS_CAPTUREBOTH | PPS_OFFSETASSERT | PPS_OFFSETCLEAR);
	if (device->pps == NULL) {
		pr_err("couldn't register PPS source\n");
		goto err_release_dev;
	}

	device->cw = clear_wait;

	port->ops->enable_irq(port);

	pr_info("attached to %s\n", port->name);

	return;

err_release_dev:
	parport_release(device->pardev);
err_unregister_dev:
	parport_unregister_device(device->pardev);
err_free:
	kfree(device);
}

static void parport_detach(struct parport *port)
{
	struct pardevice *pardev = port->cad;
	struct pps_client_pp *device;

	/* FIXME: oooh, this is ugly! */
	if (strcmp(pardev->name, KBUILD_MODNAME))
		/* not our port */
		return;

	device = pardev->private;

	port->ops->disable_irq(port);
	pps_unregister_source(device->pps);
	parport_release(pardev);
	parport_unregister_device(pardev);
	kfree(device);
}

static struct parport_driver pps_parport_driver = {
	.name = KBUILD_MODNAME,
	.attach = parport_attach,
	.detach = parport_detach,
};

/* module staff */

static int __init pps_parport_init(void)
{
	int ret;

	pr_info(DRVDESC "\n");

	if (clear_wait > CLEAR_WAIT_MAX) {
		pr_err("clear_wait value should be not greater"
				" then %d\n", CLEAR_WAIT_MAX);
		return -EINVAL;
	}

	ret = parport_register_driver(&pps_parport_driver);
	if (ret) {
		pr_err("unable to register with parport\n");
		return ret;
	}

	return  0;
}

static void __exit pps_parport_exit(void)
{
	parport_unregister_driver(&pps_parport_driver);
}

module_init(pps_parport_init);
module_exit(pps_parport_exit);

MODULE_AUTHOR("Alexander Gordeev <lasaine@lvk.cs.msu.su>");
MODULE_DESCRIPTION(DRVDESC);
MODULE_LICENSE("GPL");
Commit	Line	Data
a10203c6 AG	1	/*
	2	* pps_parport.c -- kernel parallel port PPS client
	3	*
	4	*
	5	* Copyright (C) 2009 Alexander Gordeev <lasaine@lvk.cs.msu.su>
	6	*
	7	* This program is free software; you can redistribute it and/or modify
	8	* it under the terms of the GNU General Public License as published by
	9	* the Free Software Foundation; either version 2 of the License, or
	10	* (at your option) any later version.
	11	*
	12	* This program is distributed in the hope that it will be useful,
	13	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	14	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	15	* GNU General Public License for more details.
	16	*
	17	* You should have received a copy of the GNU General Public License
	18	* along with this program; if not, write to the Free Software
	19	* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
	20	*/
	21
	22
	23	/*
	24	* TODO:
	25	* implement echo over SEL pin
	26	*/
	27
	28	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
	29
	30	#include <linux/kernel.h>
	31	#include <linux/module.h>
	32	#include <linux/init.h>
	33	#include <linux/irqnr.h>
	34	#include <linux/time.h>
	35	#include <linux/parport.h>
	36	#include <linux/pps_kernel.h>
	37
	38	#define DRVDESC "parallel port PPS client"
	39
	40	/* module parameters */
	41
	42	#define CLEAR_WAIT_MAX 100
	43	#define CLEAR_WAIT_MAX_ERRORS 5
	44
	45	static unsigned int clear_wait = 100;
	46	MODULE_PARM_DESC(clear_wait,
	47	"Maximum number of port reads when polling for signal clear,"
	48	" zero turns clear edge capture off entirely");
	49	module_param(clear_wait, uint, 0);
	50
	51
	52	/* internal per port structure */
	53	struct pps_client_pp {
	54	struct pardevice pardev; / parport device */
	55	struct pps_device pps; / PPS device */
	56	unsigned int cw; /* port clear timeout */
	57	unsigned int cw_err; /* number of timeouts */
	58	};
	59
	60	static inline int signal_is_set(struct parport *port)
	61	{
	62	return (port->ops->read_status(port) & PARPORT_STATUS_ACK) != 0;
	63	}
	64
65	/* parport interrupt handler */
66	static void parport_irq(void *handle)
67	{
68	struct pps_event_time ts_assert, ts_clear;
69	struct pps_client_pp *dev = handle;
70	struct parport *port = dev->pardev->port;
71	unsigned int i;
72	unsigned long flags;
73
74	/* first of all we get the time stamp... */
75	pps_get_ts(&ts_assert);
76
77	if (dev->cw == 0)
78	/* clear edge capture disabled */
79	goto out_assert;
80
81	/* try capture the clear edge */
82
83	/* We have to disable interrupts here. The idea is to prevent
84	* other interrupts on the same processor to introduce random
85	* lags while polling the port. Reading from IO port is known
86	* to take approximately 1us while other interrupt handlers can
87	* take much more potentially.
88	*
89	* Interrupts won't be disabled for a long time because the
90	* number of polls is limited by clear_wait parameter which is
91	* kept rather low. So it should never be an issue.
92	*/
93	local_irq_save(flags);
94	/* check the signal (no signal means the pulse is lost this time) */
95	if (!signal_is_set(port)) {
96	local_irq_restore(flags);
97	dev_err(dev->pps->dev, "lost the signal\n");
98	goto out_assert;
99	}
100
101	/* poll the port until the signal is unset */
102	for (i = dev->cw; i; i--)
103	if (!signal_is_set(port)) {
104	pps_get_ts(&ts_clear);
105	local_irq_restore(flags);
106	dev->cw_err = 0;
107	goto out_both;
108	}
109	local_irq_restore(flags);
110
111	/* timeout */
112	dev->cw_err++;
113	if (dev->cw_err >= CLEAR_WAIT_MAX_ERRORS) {
114	dev_err(dev->pps->dev, "disabled clear edge capture after %d"
115	" timeouts\n", dev->cw_err);
116	dev->cw = 0;
117	dev->cw_err = 0;
118	}
119
120	out_assert:
121	/* fire assert event */
122	pps_event(dev->pps, &ts_assert,
123	PPS_CAPTUREASSERT, NULL);
124	return;
125
126	out_both:
127	/* fire assert event */
128	pps_event(dev->pps, &ts_assert,
129	PPS_CAPTUREASSERT, NULL);
130	/* fire clear event */
131	pps_event(dev->pps, &ts_clear,
132	PPS_CAPTURECLEAR, NULL);
133	return;
134	}
135
a10203c6 AG	136	static void parport_attach(struct parport *port)
	137	{
	138	struct pps_client_pp *device;
	139	struct pps_source_info info = {
	140	.name = KBUILD_MODNAME,
	141	.path = "",
	142	.mode = PPS_CAPTUREBOTH \| \
	143	PPS_OFFSETASSERT \| PPS_OFFSETCLEAR \| \
	144	PPS_ECHOASSERT \| PPS_ECHOCLEAR \| \
	145	PPS_CANWAIT \| PPS_TSFMT_TSPEC,
a10203c6 AG	146	.owner = THIS_MODULE,
	147	.dev = NULL
	148	};
	149
	150	device = kzalloc(sizeof(struct pps_client_pp), GFP_KERNEL);
	151	if (!device) {
	152	pr_err("memory allocation failed, not attaching\n");
	153	return;
	154	}
	155
	156	device->pardev = parport_register_device(port, KBUILD_MODNAME,
4f542e3d	157	NULL, NULL, parport_irq, PARPORT_FLAG_EXCL, device);
a10203c6 AG	158	if (!device->pardev) {
	159	pr_err("couldn't register with %s\n", port->name);
	160	goto err_free;
	161	}
	162
	163	if (parport_claim_or_block(device->pardev) < 0) {
	164	pr_err("couldn't claim %s\n", port->name);
	165	goto err_unregister_dev;
	166	}
	167
	168	device->pps = pps_register_source(&info,
	169	PPS_CAPTUREBOTH \| PPS_OFFSETASSERT \| PPS_OFFSETCLEAR);
	170	if (device->pps == NULL) {
	171	pr_err("couldn't register PPS source\n");
	172	goto err_release_dev;
	173	}
	174
	175	device->cw = clear_wait;
	176
	177	port->ops->enable_irq(port);
	178
	179	pr_info("attached to %s\n", port->name);
	180
	181	return;
	182
	183	err_release_dev:
	184	parport_release(device->pardev);
	185	err_unregister_dev:
	186	parport_unregister_device(device->pardev);
	187	err_free:
	188	kfree(device);
	189	}
	190
	191	static void parport_detach(struct parport *port)
	192	{
	193	struct pardevice *pardev = port->cad;
	194	struct pps_client_pp *device;
	195
	196	/* FIXME: oooh, this is ugly! */
	197	if (strcmp(pardev->name, KBUILD_MODNAME))
	198	/* not our port */
	199	return;
	200
	201	device = pardev->private;
	202
	203	port->ops->disable_irq(port);
	204	pps_unregister_source(device->pps);
	205	parport_release(pardev);
	206	parport_unregister_device(pardev);
	207	kfree(device);
	208	}
	209
	210	static struct parport_driver pps_parport_driver = {
	211	.name = KBUILD_MODNAME,
	212	.attach = parport_attach,
	213	.detach = parport_detach,
	214	};
	215
	216	/* module staff */
	217
	218	static int __init pps_parport_init(void)
	219	{
	220	int ret;
	221
222	pr_info(DRVDESC "\n");
223
224	if (clear_wait > CLEAR_WAIT_MAX) {
225	pr_err("clear_wait value should be not greater"
226	" then %d\n", CLEAR_WAIT_MAX);
227	return -EINVAL;
228	}
229
230	ret = parport_register_driver(&pps_parport_driver);
231	if (ret) {
232	pr_err("unable to register with parport\n");
233	return ret;
234	}
235
236	return 0;
237	}
238
239	static void __exit pps_parport_exit(void)
240	{
241	parport_unregister_driver(&pps_parport_driver);
242	}
243
244	module_init(pps_parport_init);
245	module_exit(pps_parport_exit);
246
247	MODULE_AUTHOR("Alexander Gordeev <lasaine@lvk.cs.msu.su>");
248	MODULE_DESCRIPTION(DRVDESC);
249	MODULE_LICENSE("GPL");