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From:   Eliav Farber <farbere@amazon.com>
To:     <giometti@enneenne.com>, <robh+dt@kernel.org>,
        <krzysztof.kozlowski+dt@linaro.org>, <conor+dt@kernel.org>,
        <farbere@amazon.com>, <devicetree@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>
CC:     <ronenk@amazon.com>, <talel@amazon.com>, <hhhawa@amazon.com>,
        <jonnyc@amazon.com>, <itamark@amazon.com>, <shellykz@amazon.com>,
        <amitlavi@amazon.com>, <almogbs@amazon.com>
Subject: [PATCH 1/5] pps: add pulse-width calculation in nsec
Date:   Sun, 25 Jun 2023 14:21:30 +0000
Message-ID: <20230625142134.33690-2-farbere@amazon.com>
In-Reply-To: <20230625142134.33690-1-farbere@amazon.com>
References: <20230625142134.33690-1-farbere@amazon.com>
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This change adds PPS pulse-width calculation in nano seconds.
Width time can be calculated for both assert time and reset time.

Calculation can be done only if capture ASSERT and capture CLEAR modes
are both enabled.

Assert width is calculated as:
  clear-time - assert-time
and clear width is calculated as:
  assert-time - clear-time

Read-only sysfs were added to get the last pulse-width time and event
sequence.
Examples:
 * cat /sys/class/pps/pps0/pulse_width_assert
   20001450#85
 * cat /sys/class/pps/pps1/pulse_width_clear
   979893314#16

Signed-off-by: Eliav Farber <farbere@amazon.com>
---
 drivers/pps/kapi.c         | 49 ++++++++++++++++++++++++++++++++++++++
 drivers/pps/pps.c          |  9 +++++++
 drivers/pps/sysfs.c        | 30 +++++++++++++++++++++++
 include/linux/pps_kernel.h |  3 +++
 include/uapi/linux/pps.h   | 19 +++++++++++++++
 5 files changed, 110 insertions(+)

diff --git a/drivers/pps/kapi.c b/drivers/pps/kapi.c
index d9d566f70ed1..deeecfc0a3ee 100644
--- a/drivers/pps/kapi.c
+++ b/drivers/pps/kapi.c
@@ -82,6 +82,14 @@ struct pps_device *pps_register_source(struct pps_source_info *info,
 		goto pps_register_source_exit;
 	}
 
+	if ((info->mode & PPS_WIDTHBOTH) &&
+	    ((info->mode & PPS_CAPTUREBOTH) != PPS_CAPTUREBOTH)) {
+		pr_err("%s: width can't be calculated without both captures (mode = 0x%x)\n",
+		       info->name, info->mode);
+		err = -EINVAL;
+		goto pps_register_source_exit;
+	}
+
 	/* Allocate memory for the new PPS source struct */
 	pps = kzalloc(sizeof(struct pps_device), GFP_KERNEL);
 	if (pps == NULL) {
@@ -143,6 +151,39 @@ void pps_unregister_source(struct pps_device *pps)
 }
 EXPORT_SYMBOL(pps_unregister_source);
 
+static u64 pps_ktime_sub(struct pps_ktime *ts1, struct pps_ktime *ts2)
+{
+	if (ts1->sec == ts2->sec)
+		return (ts1->nsec > ts2->nsec) ? (ts1->nsec - ts2->nsec) : (ts2->nsec - ts1->nsec);
+
+	if (ts1->sec > ts2->sec)
+		return (ts1->sec - ts2->sec) * NSEC_PER_SEC + ts1->nsec - ts2->nsec;
+
+	return (ts2->sec - ts1->sec) * NSEC_PER_SEC + ts2->nsec - ts1->nsec;
+}
+
+static void pps_calc_clear_width(struct pps_device *pps)
+{
+	if (pps->clear_sequence == 0)
+		return;
+
+	pps->clear_width.sequence++;
+	pps->clear_width.nsec = pps_ktime_sub(&pps->assert_tu, &pps->clear_tu);
+	dev_dbg(pps->dev, "PPS clear width = %llu#%u\n",
+		pps->clear_width.nsec, pps->clear_width.sequence);
+}
+
+static void pps_calc_assert_width(struct pps_device *pps)
+{
+	if (pps->assert_sequence == 0)
+		return;
+
+	pps->assert_width.sequence++;
+	pps->assert_width.nsec = pps_ktime_sub(&pps->clear_tu, &pps->assert_tu);
+	dev_dbg(pps->dev, "PPS assert width = %llu#%u\n",
+		pps->assert_width.nsec, pps->assert_width.sequence);
+}
+
 /* pps_event - register a PPS event into the system
  * @pps: the PPS device
  * @ts: the event timestamp
@@ -191,6 +232,10 @@ void pps_event(struct pps_device *pps, struct pps_event_time *ts, int event,
 		dev_dbg(pps->dev, "capture assert seq #%u\n",
 			pps->assert_sequence);
 
+		/* Calculate clear pulse-width */
+		if (pps->params.mode & PPS_WIDTHCLEAR)
+			pps_calc_clear_width(pps);
+
 		captured = ~0;
 	}
 	if (event & pps->params.mode & PPS_CAPTURECLEAR) {
@@ -205,6 +250,10 @@ void pps_event(struct pps_device *pps, struct pps_event_time *ts, int event,
 		dev_dbg(pps->dev, "capture clear seq #%u\n",
 			pps->clear_sequence);
 
+		/* Calculate assert pulse-width */
+		if (pps->params.mode & PPS_WIDTHASSERT)
+			pps_calc_assert_width(pps);
+
 		captured = ~0;
 	}
 
diff --git a/drivers/pps/pps.c b/drivers/pps/pps.c
index 5d19baae6a38..8299a272af11 100644
--- a/drivers/pps/pps.c
+++ b/drivers/pps/pps.c
@@ -195,6 +195,11 @@ static long pps_cdev_ioctl(struct file *file,
 		fdata.info.clear_tu = pps->clear_tu;
 		fdata.info.current_mode = pps->current_mode;
 
+		memcpy(&fdata.info.assert_width, &pps->assert_width,
+		       sizeof(struct pps_kwidth));
+		memcpy(&fdata.info.clear_width, &pps->clear_width,
+		       sizeof(struct pps_kwidth));
+
 		spin_unlock_irq(&pps->lock);
 
 		err = copy_to_user(uarg, &fdata, sizeof(struct pps_fdata));
@@ -283,6 +288,10 @@ static long pps_cdev_compat_ioctl(struct file *file,
 				sizeof(struct pps_ktime_compat));
 		memcpy(&compat.info.clear_tu, &pps->clear_tu,
 				sizeof(struct pps_ktime_compat));
+		memcpy(&compat.info.assert_width, &pps->assert_width,
+		       sizeof(struct pps_kwidth_compat));
+		memcpy(&compat.info.clear_width, &pps->clear_width,
+		       sizeof(struct pps_kwidth_compat));
 
 		spin_unlock_irq(&pps->lock);
 
diff --git a/drivers/pps/sysfs.c b/drivers/pps/sysfs.c
index 134bc33f6ad0..3e34de77dba6 100644
--- a/drivers/pps/sysfs.c
+++ b/drivers/pps/sysfs.c
@@ -79,6 +79,34 @@ static ssize_t path_show(struct device *dev, struct device_attribute *attr,
 }
 static DEVICE_ATTR_RO(path);
 
+static ssize_t pulse_width_assert_show(struct device *dev,
+				       struct device_attribute *attr,
+				       char *buf)
+{
+	struct pps_device *pps = dev_get_drvdata(dev);
+
+	if (!(pps->info.mode & PPS_WIDTHASSERT))
+		return 0;
+
+	return sprintf(buf, "%llu#%u\n",
+		       pps->assert_width.nsec, pps->assert_width.sequence);
+}
+static DEVICE_ATTR_RO(pulse_width_assert);
+
+static ssize_t pulse_width_clear_show(struct device *dev,
+				      struct device_attribute *attr,
+				      char *buf)
+{
+	struct pps_device *pps = dev_get_drvdata(dev);
+
+	if (!(pps->info.mode & PPS_WIDTHCLEAR))
+		return 0;
+
+	return sprintf(buf, "%llu#%u\n",
+		       pps->clear_width.nsec, pps->clear_width.sequence);
+}
+static DEVICE_ATTR_RO(pulse_width_clear);
+
 static struct attribute *pps_attrs[] = {
 	&dev_attr_assert.attr,
 	&dev_attr_clear.attr,
@@ -86,6 +114,8 @@ static struct attribute *pps_attrs[] = {
 	&dev_attr_echo.attr,
 	&dev_attr_name.attr,
 	&dev_attr_path.attr,
+	&dev_attr_pulse_width_assert.attr,
+	&dev_attr_pulse_width_clear.attr,
 	NULL,
 };
 
diff --git a/include/linux/pps_kernel.h b/include/linux/pps_kernel.h
index 78c8ac4951b5..15f2338095c6 100644
--- a/include/linux/pps_kernel.h
+++ b/include/linux/pps_kernel.h
@@ -51,6 +51,9 @@ struct pps_device {
 	struct pps_ktime clear_tu;
 	int current_mode;			/* PPS mode at event time */
 
+	struct pps_kwidth assert_width;		/* PPS assert pulse-width time and event seq # */
+	struct pps_kwidth clear_width;		/* PPS clear pulse-width time and event seq # */
+
 	unsigned int last_ev;			/* last PPS event id */
 	wait_queue_head_t queue;		/* PPS event queue */
 
diff --git a/include/uapi/linux/pps.h b/include/uapi/linux/pps.h
index 009ebcd8ced5..dd93dac0afc1 100644
--- a/include/uapi/linux/pps.h
+++ b/include/uapi/linux/pps.h
@@ -64,12 +64,24 @@ struct pps_ktime_compat {
 } __attribute__((packed, aligned(4)));
 #define PPS_TIME_INVALID	(1<<0)	/* used to specify timeout==NULL */
 
+struct pps_kwidth {
+	__u64 nsec;
+	__u32 sequence;
+};
+
+struct pps_kwidth_compat {
+	__u64 nsec;
+	__u32 sequence;
+} __attribute__((packed, aligned(4)));
+
 struct pps_kinfo {
 	__u32 assert_sequence;		/* seq. num. of assert event */
 	__u32 clear_sequence; 		/* seq. num. of clear event */
 	struct pps_ktime assert_tu;	/* time of assert event */
 	struct pps_ktime clear_tu;	/* time of clear event */
 	int current_mode;		/* current mode bits */
+	struct pps_kwidth assert_width;	/* assert pulse-width time and seq. num. */
+	struct pps_kwidth clear_width;	/* clear pulse-width time and seq. num. */
 };
 
 struct pps_kinfo_compat {
@@ -78,6 +90,8 @@ struct pps_kinfo_compat {
 	struct pps_ktime_compat assert_tu;	/* time of assert event */
 	struct pps_ktime_compat clear_tu;	/* time of clear event */
 	int current_mode;			/* current mode bits */
+	struct pps_kwidth_compat assert_width;	/* assert pulse-width time and seq. num. */
+	struct pps_kwidth_compat clear_width;	/* clear pulse-width time and seq. num. */
 };
 
 struct pps_kparams {
@@ -96,6 +110,11 @@ struct pps_kparams {
 #define PPS_CAPTURECLEAR	0x02	/* capture clear events */
 #define PPS_CAPTUREBOTH		0x03	/* capture assert and clear events */
 
+/* Pulse-width calculation */
+#define PPS_WIDTHASSERT		0x04	/* calculate assert width */
+#define PPS_WIDTHCLEAR		0x08	/* calculate clear width */
+#define PPS_WIDTHBOTH		0x0c	/* calculate assert and clear width */
+
 #define PPS_OFFSETASSERT	0x10	/* apply compensation for assert event */
 #define PPS_OFFSETCLEAR		0x20	/* apply compensation for clear event */
 
-- 
2.40.1