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Subject[net-next, v5, 02/11] ptp: support ptp physical/virtual clocks conversion
Date
Support ptp physical/virtual clocks conversion via sysfs.
There will be a new attribute n_vclocks under ptp physical
clock sysfs.

- In default, the value is 0 meaning only ptp physical clock
is in use.
- Setting the value can create corresponding number of ptp
virtual clocks to use. But current physical clock is guaranteed
to stay free running.
- Setting the value back to 0 can delete virtual clocks and back
use physical clock again.

Another new attribute max_vclocks control the maximum number of
ptp vclocks.

Signed-off-by: Yangbo Lu <yangbo.lu@nxp.com>
---
Changes for v2:
- Split from v1 patch #2.
- Converted to num_vclocks for creating virtual clocks.
- Guranteed physical clock free running when using virtual
clocks.
- Fixed build warning.
- Updated copyright.
Changes for v3:
- Protected concurrency of ptp->num_vclocks accessing.
Changes for v4:
- Rephrased description in doc.
- Used unsigned int for vclocks number, and max_vclocks
for limitiation.
- Fixed mutex locking.
- Other minor fixes.
Changes for v5:
- Fixed checkpatch.
- Checked pointer parent->class->name.
---
Documentation/ABI/testing/sysfs-ptp | 20 ++++
drivers/ptp/ptp_clock.c | 26 ++++++
drivers/ptp/ptp_private.h | 21 +++++
drivers/ptp/ptp_sysfs.c | 138 ++++++++++++++++++++++++++++
4 files changed, 205 insertions(+)

diff --git a/Documentation/ABI/testing/sysfs-ptp b/Documentation/ABI/testing/sysfs-ptp
index 2363ad810ddb..d378f57c1b73 100644
--- a/Documentation/ABI/testing/sysfs-ptp
+++ b/Documentation/ABI/testing/sysfs-ptp
@@ -33,6 +33,13 @@ Description:
frequency adjustment value (a positive integer) in
parts per billion.

+What: /sys/class/ptp/ptpN/max_vclocks
+Date: May 2021
+Contact: Yangbo Lu <yangbo.lu@nxp.com>
+Description:
+ This file contains the maximum number of ptp vclocks.
+ Write integer to re-configure it.
+
What: /sys/class/ptp/ptpN/n_alarms
Date: September 2010
Contact: Richard Cochran <richardcochran@gmail.com>
@@ -61,6 +68,19 @@ Description:
This file contains the number of programmable pins
offered by the PTP hardware clock.

+What: /sys/class/ptp/ptpN/n_vclocks
+Date: May 2021
+Contact: Yangbo Lu <yangbo.lu@nxp.com>
+Description:
+ This file contains the number of virtual PTP clocks in
+ use. By default, the value is 0 meaning that only the
+ physical clock is in use. Setting the value creates
+ the corresponding number of virtual clocks and causes
+ the physical clock to become free running. Setting the
+ value back to 0 deletes the virtual clocks and
+ switches the physical clock back to normal, adjustable
+ operation.
+
What: /sys/class/ptp/ptpN/pins
Date: March 2014
Contact: Richard Cochran <richardcochran@gmail.com>
diff --git a/drivers/ptp/ptp_clock.c b/drivers/ptp/ptp_clock.c
index a23a37a4d5dc..7334f478dde7 100644
--- a/drivers/ptp/ptp_clock.c
+++ b/drivers/ptp/ptp_clock.c
@@ -76,6 +76,11 @@ static int ptp_clock_settime(struct posix_clock *pc, const struct timespec64 *tp
{
struct ptp_clock *ptp = container_of(pc, struct ptp_clock, clock);

+ if (ptp_vclock_in_use(ptp)) {
+ pr_err("ptp: virtual clock in use\n");
+ return -EBUSY;
+ }
+
return ptp->info->settime64(ptp->info, tp);
}

@@ -97,6 +102,11 @@ static int ptp_clock_adjtime(struct posix_clock *pc, struct __kernel_timex *tx)
struct ptp_clock_info *ops;
int err = -EOPNOTSUPP;

+ if (ptp_vclock_in_use(ptp)) {
+ pr_err("ptp: virtual clock in use\n");
+ return -EBUSY;
+ }
+
ops = ptp->info;

if (tx->modes & ADJ_SETOFFSET) {
@@ -161,6 +171,7 @@ static void ptp_clock_release(struct device *dev)
ptp_cleanup_pin_groups(ptp);
mutex_destroy(&ptp->tsevq_mux);
mutex_destroy(&ptp->pincfg_mux);
+ mutex_destroy(&ptp->n_vclocks_mux);
ida_simple_remove(&ptp_clocks_map, ptp->index);
kfree(ptp);
}
@@ -208,6 +219,7 @@ struct ptp_clock *ptp_clock_register(struct ptp_clock_info *info,
spin_lock_init(&ptp->tsevq.lock);
mutex_init(&ptp->tsevq_mux);
mutex_init(&ptp->pincfg_mux);
+ mutex_init(&ptp->n_vclocks_mux);
init_waitqueue_head(&ptp->tsev_wq);

if (ptp->info->do_aux_work) {
@@ -221,6 +233,14 @@ struct ptp_clock *ptp_clock_register(struct ptp_clock_info *info,
ptp->pps_source->lookup_cookie = ptp;
}

+ /* PTP virtual clock is being registered under physical clock */
+ if (parent->class && parent->class->name &&
+ strcmp(parent->class->name, "ptp") == 0)
+ ptp->is_virtual_clock = true;
+
+ if (!ptp->is_virtual_clock)
+ ptp->max_vclocks = PTP_DEFAULT_MAX_VCLOCKS;
+
err = ptp_populate_pin_groups(ptp);
if (err)
goto no_pin_groups;
@@ -270,6 +290,7 @@ struct ptp_clock *ptp_clock_register(struct ptp_clock_info *info,
kworker_err:
mutex_destroy(&ptp->tsevq_mux);
mutex_destroy(&ptp->pincfg_mux);
+ mutex_destroy(&ptp->n_vclocks_mux);
ida_simple_remove(&ptp_clocks_map, index);
no_slot:
kfree(ptp);
@@ -280,6 +301,11 @@ EXPORT_SYMBOL(ptp_clock_register);

int ptp_clock_unregister(struct ptp_clock *ptp)
{
+ if (ptp_vclock_in_use(ptp)) {
+ pr_err("ptp: virtual clock in use\n");
+ return -EBUSY;
+ }
+
ptp->defunct = 1;
wake_up_interruptible(&ptp->tsev_wq);

diff --git a/drivers/ptp/ptp_private.h b/drivers/ptp/ptp_private.h
index 853b79b6b30e..87cb55953b69 100644
--- a/drivers/ptp/ptp_private.h
+++ b/drivers/ptp/ptp_private.h
@@ -18,6 +18,7 @@

#define PTP_MAX_TIMESTAMPS 128
#define PTP_BUF_TIMESTAMPS 30
+#define PTP_DEFAULT_MAX_VCLOCKS 20

struct timestamp_event_queue {
struct ptp_extts_event buf[PTP_MAX_TIMESTAMPS];
@@ -46,6 +47,10 @@ struct ptp_clock {
const struct attribute_group *pin_attr_groups[2];
struct kthread_worker *kworker;
struct kthread_delayed_work aux_work;
+ unsigned int max_vclocks;
+ unsigned int n_vclocks;
+ struct mutex n_vclocks_mux; /* protect concurrent n_vclocks access */
+ bool is_virtual_clock;
};

#define info_to_vclock(d) container_of((d), struct ptp_vclock, info)
@@ -74,6 +79,22 @@ static inline int queue_cnt(struct timestamp_event_queue *q)
return cnt < 0 ? PTP_MAX_TIMESTAMPS + cnt : cnt;
}

+/* Check if ptp virtual clock is in use */
+static inline bool ptp_vclock_in_use(struct ptp_clock *ptp)
+{
+ bool in_use = false;
+
+ if (mutex_lock_interruptible(&ptp->n_vclocks_mux))
+ return true;
+
+ if (!ptp->is_virtual_clock && ptp->n_vclocks)
+ in_use = true;
+
+ mutex_unlock(&ptp->n_vclocks_mux);
+
+ return in_use;
+}
+
/*
* see ptp_chardev.c
*/
diff --git a/drivers/ptp/ptp_sysfs.c b/drivers/ptp/ptp_sysfs.c
index be076a91e20e..0b05041783a5 100644
--- a/drivers/ptp/ptp_sysfs.c
+++ b/drivers/ptp/ptp_sysfs.c
@@ -3,6 +3,7 @@
* PTP 1588 clock support - sysfs interface.
*
* Copyright (C) 2010 OMICRON electronics GmbH
+ * Copyright 2021 NXP
*/
#include <linux/capability.h>
#include <linux/slab.h>
@@ -148,6 +149,137 @@ static ssize_t pps_enable_store(struct device *dev,
}
static DEVICE_ATTR(pps_enable, 0220, NULL, pps_enable_store);

+static int unregister_vclock(struct device *dev, void *data)
+{
+ struct ptp_clock *ptp = dev_get_drvdata(dev);
+ struct ptp_clock_info *info = ptp->info;
+ struct ptp_vclock *vclock;
+ u8 *num = data;
+
+ vclock = info_to_vclock(info);
+ dev_info(dev->parent, "delete virtual clock ptp%d\n",
+ vclock->clock->index);
+
+ ptp_vclock_unregister(vclock);
+ (*num)--;
+
+ /* For break. Not error. */
+ if (*num == 0)
+ return -EINVAL;
+
+ return 0;
+}
+
+static ssize_t n_vclocks_show(struct device *dev,
+ struct device_attribute *attr, char *page)
+{
+ struct ptp_clock *ptp = dev_get_drvdata(dev);
+ ssize_t size;
+
+ if (mutex_lock_interruptible(&ptp->n_vclocks_mux))
+ return -ERESTARTSYS;
+
+ size = snprintf(page, PAGE_SIZE - 1, "%d\n", ptp->n_vclocks);
+
+ mutex_unlock(&ptp->n_vclocks_mux);
+
+ return size;
+}
+
+static ssize_t n_vclocks_store(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ struct ptp_clock *ptp = dev_get_drvdata(dev);
+ struct ptp_vclock *vclock;
+ int err = -EINVAL;
+ u32 num, i;
+
+ if (kstrtou32(buf, 0, &num))
+ return err;
+
+ if (mutex_lock_interruptible(&ptp->n_vclocks_mux))
+ return -ERESTARTSYS;
+
+ if (num > ptp->max_vclocks) {
+ dev_err(dev, "max value is %d\n", ptp->max_vclocks);
+ goto out;
+ }
+
+ /* Need to create more vclocks */
+ if (num > ptp->n_vclocks) {
+ for (i = 0; i < num - ptp->n_vclocks; i++) {
+ vclock = ptp_vclock_register(ptp);
+ if (!vclock)
+ goto out;
+
+ dev_info(dev, "new virtual clock ptp%d\n",
+ vclock->clock->index);
+ }
+ }
+
+ /* Need to delete vclocks */
+ if (num < ptp->n_vclocks) {
+ i = ptp->n_vclocks - num;
+ device_for_each_child_reverse(dev, &i,
+ unregister_vclock);
+ }
+
+ if (num == 0)
+ dev_info(dev, "only physical clock in use now\n");
+ else
+ dev_info(dev, "guarantee physical clock free running\n");
+
+ ptp->n_vclocks = num;
+ mutex_unlock(&ptp->n_vclocks_mux);
+
+ return count;
+out:
+ mutex_unlock(&ptp->n_vclocks_mux);
+ return err;
+}
+static DEVICE_ATTR_RW(n_vclocks);
+
+static ssize_t max_vclocks_show(struct device *dev,
+ struct device_attribute *attr, char *page)
+{
+ struct ptp_clock *ptp = dev_get_drvdata(dev);
+ ssize_t size;
+
+ size = snprintf(page, PAGE_SIZE - 1, "%d\n", ptp->max_vclocks);
+
+ return size;
+}
+
+static ssize_t max_vclocks_store(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ struct ptp_clock *ptp = dev_get_drvdata(dev);
+ u32 max;
+
+ if (kstrtou32(buf, 0, &max) || max == 0)
+ return -EINVAL;
+
+ if (max == ptp->max_vclocks)
+ return count;
+
+ if (mutex_lock_interruptible(&ptp->n_vclocks_mux))
+ return -ERESTARTSYS;
+
+ if (max < ptp->n_vclocks) {
+ mutex_unlock(&ptp->n_vclocks_mux);
+ return -EINVAL;
+ }
+
+ ptp->max_vclocks = max;
+
+ mutex_unlock(&ptp->n_vclocks_mux);
+
+ return count;
+}
+static DEVICE_ATTR_RW(max_vclocks);
+
static struct attribute *ptp_attrs[] = {
&dev_attr_clock_name.attr,

@@ -162,6 +294,8 @@ static struct attribute *ptp_attrs[] = {
&dev_attr_fifo.attr,
&dev_attr_period.attr,
&dev_attr_pps_enable.attr,
+ &dev_attr_n_vclocks.attr,
+ &dev_attr_max_vclocks.attr,
NULL
};

@@ -183,6 +317,10 @@ static umode_t ptp_is_attribute_visible(struct kobject *kobj,
} else if (attr == &dev_attr_pps_enable.attr) {
if (!info->pps)
mode = 0;
+ } else if (attr == &dev_attr_n_vclocks.attr ||
+ attr == &dev_attr_max_vclocks.attr) {
+ if (ptp->is_virtual_clock)
+ mode = 0;
}

return mode;
--
2.25.1
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