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authorGrygorii Strashko <grygorii.strashko@ti.com>2017-07-28 17:30:02 -0500
committerDavid S. Miller <davem@davemloft.net>2017-08-01 15:22:55 -0700
commitd9535cb7b7603aeb549c697ecdf92024e4d0a650 (patch)
treee03c4fc2145d6df6afebf07ec5f4c21ad62cd880 /include
parentbc78d646e708dabd1744ca98744dea316f459497 (diff)
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ptp: introduce ptp auxiliary worker
Many PTP drivers required to perform some asynchronous or periodic work, like periodically handling PHC counter overflow or handle delayed timestamp for RX/TX network packets. In most of the cases, such work is implemented using workqueues. Unfortunately, Kernel workqueues might introduce significant delay in work scheduling under high system load and on -RT, which could cause misbehavior of PTP drivers due to internal counter overflow, for example, and there is no way to tune its execution policy and priority manuallly. Hence, The kthread_worker can be used insted of workqueues, as it create separte named kthread for each worker and its its execution policy and priority can be configured using chrt tool. This prblem was reported for two drivers TI CPSW CPTS and dp83640, so instead of modifying each of these driver it was proposed to add PTP auxiliary worker to the PHC subsystem. The patch adds PTP auxiliary worker in PHC subsystem using kthread_worker and kthread_delayed_work and introduces two new PHC subsystem APIs: - long (*do_aux_work)(struct ptp_clock_info *ptp) callback in ptp_clock_info structure, which driver should assign if it require to perform asynchronous or periodic work. Driver should return the delay of the PTP next auxiliary work scheduling time (>=0) or negative value in case further scheduling is not required. - int ptp_schedule_worker(struct ptp_clock *ptp, unsigned long delay) which allows schedule PTP auxiliary work. The name of kthread_worker thread corresponds PTP PHC device name "ptp%d". Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include')
-rw-r--r--include/linux/ptp_clock_kernel.h20
1 files changed, 20 insertions, 0 deletions
diff --git a/include/linux/ptp_clock_kernel.h b/include/linux/ptp_clock_kernel.h
index a026bfd089db..51349d124ee5 100644
--- a/include/linux/ptp_clock_kernel.h
+++ b/include/linux/ptp_clock_kernel.h
@@ -99,6 +99,11 @@ struct system_device_crosststamp;
* parameter func: the desired function to use.
* parameter chan: the function channel index to use.
*
+ * @do_work: Request driver to perform auxiliary (periodic) operations
+ * Driver should return delay of the next auxiliary work scheduling
+ * time (>=0) or negative value in case further scheduling
+ * is not required.
+ *
* Drivers should embed their ptp_clock_info within a private
* structure, obtaining a reference to it using container_of().
*
@@ -126,6 +131,7 @@ struct ptp_clock_info {
struct ptp_clock_request *request, int on);
int (*verify)(struct ptp_clock_info *ptp, unsigned int pin,
enum ptp_pin_function func, unsigned int chan);
+ long (*do_aux_work)(struct ptp_clock_info *ptp);
};
struct ptp_clock;
@@ -211,6 +217,16 @@ extern int ptp_clock_index(struct ptp_clock *ptp);
int ptp_find_pin(struct ptp_clock *ptp,
enum ptp_pin_function func, unsigned int chan);
+/**
+ * ptp_schedule_worker() - schedule ptp auxiliary work
+ *
+ * @ptp: The clock obtained from ptp_clock_register().
+ * @delay: number of jiffies to wait before queuing
+ * See kthread_queue_delayed_work() for more info.
+ */
+
+int ptp_schedule_worker(struct ptp_clock *ptp, unsigned long delay);
+
#else
static inline struct ptp_clock *ptp_clock_register(struct ptp_clock_info *info,
struct device *parent)
@@ -225,6 +241,10 @@ static inline int ptp_clock_index(struct ptp_clock *ptp)
static inline int ptp_find_pin(struct ptp_clock *ptp,
enum ptp_pin_function func, unsigned int chan)
{ return -1; }
+static inline int ptp_schedule_worker(struct ptp_clock *ptp,
+ unsigned long delay)
+{ return -EOPNOTSUPP; }
+
#endif
#endif