kernel_optimize_test/drivers/ptp/ptp_clock.c
Richard Cochran 62582a7ee7 ptp: Avoid deadlocks in the programmable pin code.
The PTP Hardware Clock (PHC) subsystem offers an API for configuring
programmable pins.  User space sets or gets the settings using ioctls,
and drivers verify dialed settings via a callback.  Drivers may also
query pin settings by calling the ptp_find_pin() method.

Although the core subsystem protects concurrent access to the pin
settings, the implementation places illogical restrictions on how
drivers may call ptp_find_pin().  When enabling an auxiliary function
via the .enable(on=1) callback, drivers may invoke the pin finding
method, but when disabling with .enable(on=0) drivers are not
permitted to do so.  With the exception of the mv88e6xxx, all of the
PHC drivers do respect this restriction, but still the locking pattern
is both confusing and unnecessary.

This patch changes the locking implementation to allow PHC drivers to
freely call ptp_find_pin() from their .enable() and .verify()
callbacks.

V2 ChangeLog:
- fixed spelling in the kernel doc
- add Vladimir's tested by tag

Signed-off-by: Richard Cochran <richardcochran@gmail.com>
Reported-by: Yangbo Lu <yangbo.lu@nxp.com>
Tested-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-03-30 11:16:38 -07:00

430 lines
9.7 KiB
C

// SPDX-License-Identifier: GPL-2.0-or-later
/*
* PTP 1588 clock support
*
* Copyright (C) 2010 OMICRON electronics GmbH
*/
#include <linux/idr.h>
#include <linux/device.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/posix-clock.h>
#include <linux/pps_kernel.h>
#include <linux/slab.h>
#include <linux/syscalls.h>
#include <linux/uaccess.h>
#include <uapi/linux/sched/types.h>
#include "ptp_private.h"
#define PTP_MAX_ALARMS 4
#define PTP_PPS_DEFAULTS (PPS_CAPTUREASSERT | PPS_OFFSETASSERT)
#define PTP_PPS_EVENT PPS_CAPTUREASSERT
#define PTP_PPS_MODE (PTP_PPS_DEFAULTS | PPS_CANWAIT | PPS_TSFMT_TSPEC)
/* private globals */
static dev_t ptp_devt;
static struct class *ptp_class;
static DEFINE_IDA(ptp_clocks_map);
/* time stamp event queue operations */
static inline int queue_free(struct timestamp_event_queue *q)
{
return PTP_MAX_TIMESTAMPS - queue_cnt(q) - 1;
}
static void enqueue_external_timestamp(struct timestamp_event_queue *queue,
struct ptp_clock_event *src)
{
struct ptp_extts_event *dst;
unsigned long flags;
s64 seconds;
u32 remainder;
seconds = div_u64_rem(src->timestamp, 1000000000, &remainder);
spin_lock_irqsave(&queue->lock, flags);
dst = &queue->buf[queue->tail];
dst->index = src->index;
dst->t.sec = seconds;
dst->t.nsec = remainder;
if (!queue_free(queue))
queue->head = (queue->head + 1) % PTP_MAX_TIMESTAMPS;
queue->tail = (queue->tail + 1) % PTP_MAX_TIMESTAMPS;
spin_unlock_irqrestore(&queue->lock, flags);
}
s32 scaled_ppm_to_ppb(long ppm)
{
/*
* The 'freq' field in the 'struct timex' is in parts per
* million, but with a 16 bit binary fractional field.
*
* We want to calculate
*
* ppb = scaled_ppm * 1000 / 2^16
*
* which simplifies to
*
* ppb = scaled_ppm * 125 / 2^13
*/
s64 ppb = 1 + ppm;
ppb *= 125;
ppb >>= 13;
return (s32) ppb;
}
EXPORT_SYMBOL(scaled_ppm_to_ppb);
/* posix clock implementation */
static int ptp_clock_getres(struct posix_clock *pc, struct timespec64 *tp)
{
tp->tv_sec = 0;
tp->tv_nsec = 1;
return 0;
}
static int ptp_clock_settime(struct posix_clock *pc, const struct timespec64 *tp)
{
struct ptp_clock *ptp = container_of(pc, struct ptp_clock, clock);
return ptp->info->settime64(ptp->info, tp);
}
static int ptp_clock_gettime(struct posix_clock *pc, struct timespec64 *tp)
{
struct ptp_clock *ptp = container_of(pc, struct ptp_clock, clock);
int err;
if (ptp->info->gettimex64)
err = ptp->info->gettimex64(ptp->info, tp, NULL);
else
err = ptp->info->gettime64(ptp->info, tp);
return err;
}
static int ptp_clock_adjtime(struct posix_clock *pc, struct __kernel_timex *tx)
{
struct ptp_clock *ptp = container_of(pc, struct ptp_clock, clock);
struct ptp_clock_info *ops;
int err = -EOPNOTSUPP;
ops = ptp->info;
if (tx->modes & ADJ_SETOFFSET) {
struct timespec64 ts;
ktime_t kt;
s64 delta;
ts.tv_sec = tx->time.tv_sec;
ts.tv_nsec = tx->time.tv_usec;
if (!(tx->modes & ADJ_NANO))
ts.tv_nsec *= 1000;
if ((unsigned long) ts.tv_nsec >= NSEC_PER_SEC)
return -EINVAL;
kt = timespec64_to_ktime(ts);
delta = ktime_to_ns(kt);
err = ops->adjtime(ops, delta);
} else if (tx->modes & ADJ_FREQUENCY) {
s32 ppb = scaled_ppm_to_ppb(tx->freq);
if (ppb > ops->max_adj || ppb < -ops->max_adj)
return -ERANGE;
if (ops->adjfine)
err = ops->adjfine(ops, tx->freq);
else
err = ops->adjfreq(ops, ppb);
ptp->dialed_frequency = tx->freq;
} else if (tx->modes == 0) {
tx->freq = ptp->dialed_frequency;
err = 0;
}
return err;
}
static struct posix_clock_operations ptp_clock_ops = {
.owner = THIS_MODULE,
.clock_adjtime = ptp_clock_adjtime,
.clock_gettime = ptp_clock_gettime,
.clock_getres = ptp_clock_getres,
.clock_settime = ptp_clock_settime,
.ioctl = ptp_ioctl,
.open = ptp_open,
.poll = ptp_poll,
.read = ptp_read,
};
static void ptp_clock_release(struct device *dev)
{
struct ptp_clock *ptp = container_of(dev, struct ptp_clock, dev);
ptp_cleanup_pin_groups(ptp);
mutex_destroy(&ptp->tsevq_mux);
mutex_destroy(&ptp->pincfg_mux);
ida_simple_remove(&ptp_clocks_map, ptp->index);
kfree(ptp);
}
static void ptp_aux_kworker(struct kthread_work *work)
{
struct ptp_clock *ptp = container_of(work, struct ptp_clock,
aux_work.work);
struct ptp_clock_info *info = ptp->info;
long delay;
delay = info->do_aux_work(info);
if (delay >= 0)
kthread_queue_delayed_work(ptp->kworker, &ptp->aux_work, delay);
}
/* public interface */
struct ptp_clock *ptp_clock_register(struct ptp_clock_info *info,
struct device *parent)
{
struct ptp_clock *ptp;
int err = 0, index, major = MAJOR(ptp_devt);
if (info->n_alarm > PTP_MAX_ALARMS)
return ERR_PTR(-EINVAL);
/* Initialize a clock structure. */
err = -ENOMEM;
ptp = kzalloc(sizeof(struct ptp_clock), GFP_KERNEL);
if (ptp == NULL)
goto no_memory;
index = ida_simple_get(&ptp_clocks_map, 0, MINORMASK + 1, GFP_KERNEL);
if (index < 0) {
err = index;
goto no_slot;
}
ptp->clock.ops = ptp_clock_ops;
ptp->info = info;
ptp->devid = MKDEV(major, index);
ptp->index = index;
spin_lock_init(&ptp->tsevq.lock);
mutex_init(&ptp->tsevq_mux);
mutex_init(&ptp->pincfg_mux);
init_waitqueue_head(&ptp->tsev_wq);
if (ptp->info->do_aux_work) {
kthread_init_delayed_work(&ptp->aux_work, ptp_aux_kworker);
ptp->kworker = kthread_create_worker(0, "ptp%d", ptp->index);
if (IS_ERR(ptp->kworker)) {
err = PTR_ERR(ptp->kworker);
pr_err("failed to create ptp aux_worker %d\n", err);
goto kworker_err;
}
}
err = ptp_populate_pin_groups(ptp);
if (err)
goto no_pin_groups;
/* Register a new PPS source. */
if (info->pps) {
struct pps_source_info pps;
memset(&pps, 0, sizeof(pps));
snprintf(pps.name, PPS_MAX_NAME_LEN, "ptp%d", index);
pps.mode = PTP_PPS_MODE;
pps.owner = info->owner;
ptp->pps_source = pps_register_source(&pps, PTP_PPS_DEFAULTS);
if (IS_ERR(ptp->pps_source)) {
err = PTR_ERR(ptp->pps_source);
pr_err("failed to register pps source\n");
goto no_pps;
}
}
/* Initialize a new device of our class in our clock structure. */
device_initialize(&ptp->dev);
ptp->dev.devt = ptp->devid;
ptp->dev.class = ptp_class;
ptp->dev.parent = parent;
ptp->dev.groups = ptp->pin_attr_groups;
ptp->dev.release = ptp_clock_release;
dev_set_drvdata(&ptp->dev, ptp);
dev_set_name(&ptp->dev, "ptp%d", ptp->index);
/* Create a posix clock and link it to the device. */
err = posix_clock_register(&ptp->clock, &ptp->dev);
if (err) {
pr_err("failed to create posix clock\n");
goto no_clock;
}
return ptp;
no_clock:
if (ptp->pps_source)
pps_unregister_source(ptp->pps_source);
no_pps:
ptp_cleanup_pin_groups(ptp);
no_pin_groups:
if (ptp->kworker)
kthread_destroy_worker(ptp->kworker);
kworker_err:
mutex_destroy(&ptp->tsevq_mux);
mutex_destroy(&ptp->pincfg_mux);
ida_simple_remove(&ptp_clocks_map, index);
no_slot:
kfree(ptp);
no_memory:
return ERR_PTR(err);
}
EXPORT_SYMBOL(ptp_clock_register);
int ptp_clock_unregister(struct ptp_clock *ptp)
{
ptp->defunct = 1;
wake_up_interruptible(&ptp->tsev_wq);
if (ptp->kworker) {
kthread_cancel_delayed_work_sync(&ptp->aux_work);
kthread_destroy_worker(ptp->kworker);
}
/* Release the clock's resources. */
if (ptp->pps_source)
pps_unregister_source(ptp->pps_source);
posix_clock_unregister(&ptp->clock);
return 0;
}
EXPORT_SYMBOL(ptp_clock_unregister);
void ptp_clock_event(struct ptp_clock *ptp, struct ptp_clock_event *event)
{
struct pps_event_time evt;
switch (event->type) {
case PTP_CLOCK_ALARM:
break;
case PTP_CLOCK_EXTTS:
enqueue_external_timestamp(&ptp->tsevq, event);
wake_up_interruptible(&ptp->tsev_wq);
break;
case PTP_CLOCK_PPS:
pps_get_ts(&evt);
pps_event(ptp->pps_source, &evt, PTP_PPS_EVENT, NULL);
break;
case PTP_CLOCK_PPSUSR:
pps_event(ptp->pps_source, &event->pps_times,
PTP_PPS_EVENT, NULL);
break;
}
}
EXPORT_SYMBOL(ptp_clock_event);
int ptp_clock_index(struct ptp_clock *ptp)
{
return ptp->index;
}
EXPORT_SYMBOL(ptp_clock_index);
int ptp_find_pin(struct ptp_clock *ptp,
enum ptp_pin_function func, unsigned int chan)
{
struct ptp_pin_desc *pin = NULL;
int i;
for (i = 0; i < ptp->info->n_pins; i++) {
if (ptp->info->pin_config[i].func == func &&
ptp->info->pin_config[i].chan == chan) {
pin = &ptp->info->pin_config[i];
break;
}
}
return pin ? i : -1;
}
EXPORT_SYMBOL(ptp_find_pin);
int ptp_find_pin_unlocked(struct ptp_clock *ptp,
enum ptp_pin_function func, unsigned int chan)
{
int result;
mutex_lock(&ptp->pincfg_mux);
result = ptp_find_pin(ptp, func, chan);
mutex_unlock(&ptp->pincfg_mux);
return result;
}
EXPORT_SYMBOL(ptp_find_pin_unlocked);
int ptp_schedule_worker(struct ptp_clock *ptp, unsigned long delay)
{
return kthread_mod_delayed_work(ptp->kworker, &ptp->aux_work, delay);
}
EXPORT_SYMBOL(ptp_schedule_worker);
void ptp_cancel_worker_sync(struct ptp_clock *ptp)
{
kthread_cancel_delayed_work_sync(&ptp->aux_work);
}
EXPORT_SYMBOL(ptp_cancel_worker_sync);
/* module operations */
static void __exit ptp_exit(void)
{
class_destroy(ptp_class);
unregister_chrdev_region(ptp_devt, MINORMASK + 1);
ida_destroy(&ptp_clocks_map);
}
static int __init ptp_init(void)
{
int err;
ptp_class = class_create(THIS_MODULE, "ptp");
if (IS_ERR(ptp_class)) {
pr_err("ptp: failed to allocate class\n");
return PTR_ERR(ptp_class);
}
err = alloc_chrdev_region(&ptp_devt, 0, MINORMASK + 1, "ptp");
if (err < 0) {
pr_err("ptp: failed to allocate device region\n");
goto no_region;
}
ptp_class->dev_groups = ptp_groups;
pr_info("PTP clock support registered\n");
return 0;
no_region:
class_destroy(ptp_class);
return err;
}
subsys_initcall(ptp_init);
module_exit(ptp_exit);
MODULE_AUTHOR("Richard Cochran <richardcochran@gmail.com>");
MODULE_DESCRIPTION("PTP clocks support");
MODULE_LICENSE("GPL");