RE: [PATCH] pps: add epoll support

[Denis OSTERLAND-HEIM <denis.osterland@diehl.com>]

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Gentle ping

-----Original Message-----
From: Denis OSTERLAND-HEIM 
Sent: Monday, January 20, 2025 2:11 PM
To: 'Rodolfo Giometti' <giometti@enneenne.com>
Cc: linux-kernel@vger.kernel.org
Subject: [PATCH] pps: add epoll support

This patch adds pps_context to store the per file read counter.

Signed-off-by: Denis Osterland-Heim <denis.osterland@diehl.com>
---
 drivers/pps/pps.c | 33 ++++++++++++++++++++++++++-------
 1 file changed, 26 insertions(+), 7 deletions(-)

diff --git a/drivers/pps/pps.c b/drivers/pps/pps.c
index 25d47907db17..b5834c592e2a 100644
--- a/drivers/pps/pps.c
+++ b/drivers/pps/pps.c
@@ -21,6 +21,12 @@
 
 #include "kc.h"
 
+struct pps_context {
+	struct pps_device *pps;
+	unsigned int ev;
+};
+
+
 /*
  * Local variables
  */
@@ -37,17 +43,19 @@ static DEFINE_IDR(pps_idr);
 
 static __poll_t pps_cdev_poll(struct file *file, poll_table *wait)
 {
-	struct pps_device *pps = file->private_data;
+	struct pps_context *ctx = file->private_data;
+	struct pps_device *pps = ctx->pps;
 
 	poll_wait(file, &pps->queue, wait);
 
-	return EPOLLIN | EPOLLRDNORM;
+	return (ctx->ev != pps->last_ev) ? (EPOLLIN | EPOLLRDNORM) : 0;
 }
 
 static int pps_cdev_fasync(int fd, struct file *file, int on)
 {
-	struct pps_device *pps = file->private_data;
-	return fasync_helper(fd, file, on, &pps->async_queue);
+	struct pps_context *ctx = file->private_data;
+
+	return fasync_helper(fd, file, on, &ctx->pps->async_queue);
 }
 
 static int pps_cdev_pps_fetch(struct pps_device *pps, struct pps_fdata *fdata)
@@ -90,7 +98,8 @@ static int pps_cdev_pps_fetch(struct pps_device *pps, struct pps_fdata *fdata)
 static long pps_cdev_ioctl(struct file *file,
 		unsigned int cmd, unsigned long arg)
 {
-	struct pps_device *pps = file->private_data;
+	struct pps_context *ctx = file->private_data;
+	struct pps_device *pps = ctx->pps;
 	struct pps_kparams params;
 	void __user *uarg = (void __user *) arg;
 	int __user *iuarg = (int __user *) arg;
@@ -189,6 +198,7 @@ static long pps_cdev_ioctl(struct file *file,
 		/* Return the fetched timestamp */
 		spin_lock_irq(&pps->lock);
 
+		ctx->ev = pps->last_ev;
 		fdata.info.assert_sequence = pps->assert_sequence;
 		fdata.info.clear_sequence = pps->clear_sequence;
 		fdata.info.assert_tu = pps->assert_tu;
@@ -249,7 +259,8 @@ static long pps_cdev_ioctl(struct file *file,
 static long pps_cdev_compat_ioctl(struct file *file,
 		unsigned int cmd, unsigned long arg)
 {
-	struct pps_device *pps = file->private_data;
+	struct pps_context *ctx = file->private_data;
+	struct pps_device *pps = ctx->pps;
 	void __user *uarg = (void __user *) arg;
 
 	cmd = _IOC(_IOC_DIR(cmd), _IOC_TYPE(cmd), _IOC_NR(cmd), sizeof(void *));
@@ -275,6 +286,7 @@ static long pps_cdev_compat_ioctl(struct file *file,
 		/* Return the fetched timestamp */
 		spin_lock_irq(&pps->lock);
 
+		ctx->ev = pps->last_ev;
 		compat.info.assert_sequence = pps->assert_sequence;
 		compat.info.clear_sequence = pps->clear_sequence;
 		compat.info.current_mode = pps->current_mode;
@@ -300,7 +312,13 @@ static int pps_cdev_open(struct inode *inode, struct file *file)
 {
 	struct pps_device *pps = container_of(inode->i_cdev,
 						struct pps_device, cdev);
-	file->private_data = pps;
+	struct pps_context *ctx = kzalloc(sizeof(struct pps_context), GFP_KERNEL);
+
+	if (unlikely(ZERO_OR_NULL_PTR(ctx)))
+		return -ENOMEM;
+	file->private_data = ctx;
+	ctx->pps = pps;
+	ctx->ev = pps->last_ev;
 	kobject_get(&pps->dev->kobj);
 	return 0;
 }
@@ -309,6 +327,7 @@ static int pps_cdev_release(struct inode *inode, struct file *file)
 {
 	struct pps_device *pps = container_of(inode->i_cdev,
 						struct pps_device, cdev);
+	kfree(file->private_data);
 	kobject_put(&pps->dev->kobj);
 	return 0;
 }
-- 
2.45.2

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