ice: enable transmit timestamps for E810 devices

Add support for enabling Tx timestamp requests for outgoing packets on
E810 devices.

The ice hardware can support multiple outstanding Tx timestamp requests.
When sending a descriptor to hardware, a Tx timestamp request is made by
setting a request bit, and assigning an index that represents which Tx
timestamp index to store the timestamp in.

Hardware makes no effort to synchronize the index use, so it is up to
software to ensure that Tx timestamp indexes are not re-used before the
timestamp is reported back.

To do this, introduce a Tx timestamp tracker which will keep track of
currently in-use indexes.

In the hot path, if a packet has a timestamp request, an index will be
requested from the tracker. Unfortunately, this does require a lock as
the indexes are shared across all queues on a PHY. There are not enough
indexes to reliably assign only 1 to each queue.

For the E810 devices, the timestamp indexes are not shared across PHYs,
so each port can have its own tracking.

Once hardware captures a timestamp, an interrupt is fired. In this
interrupt, trigger a new work item that will figure out which timestamp
was completed, and report the timestamp back to the stack.

This function loops through the Tx timestamp indexes and checks whether
there is now a valid timestamp. If so, it clears the PHY timestamp
indication in the PHY memory, locks and removes the SKB and bit in the
tracker, then reports the timestamp to the stack.

It is possible in some cases that a timestamp request will be initiated
but never completed. This might occur if the packet is dropped by
software or hardware before it reaches the PHY.

Add a task to the periodic work function that will check whether
a timestamp request is more than a few seconds old. If so, the timestamp
index is cleared in the PHY, and the SKB is released.

Just as with Rx timestamps, the Tx timestamps are only 40 bits wide, and
use the same overall logic for extending to 64 bits of nanoseconds.

With this change, E810 devices should be able to perform basic PTP
functionality.

Future changes will extend the support to cover the E822-based devices.

Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Tony Brelinski <tonyx.brelinski@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

1 files changed, 91 insertions, 0 deletions

diff --git a/drivers/net/ethernet/intel/ice/ice_ptp.h b/drivers/net/ethernet/intel/ice/ice_ptp.h
index 48850391ab28..41e14f98f0e6 100644
--- a/drivers/net/ethernet/intel/ice/ice_ptp.h
+++ b/drivers/net/ethernet/intel/ice/ice_ptp.h
@@ -9,8 +9,82 @@
 
 #include "ice_ptp_hw.h"
 
+/* The ice hardware captures Tx hardware timestamps in the PHY. The timestamp
+ * is stored in a buffer of registers. Depending on the specific hardware,
+ * this buffer might be shared across multiple PHY ports.
+ *
+ * On transmit of a packet to be timestamped, software is responsible for
+ * selecting an open index. Hardware makes no attempt to lock or prevent
+ * re-use of an index for multiple packets.
+ *
+ * To handle this, timestamp indexes must be tracked by software to ensure
+ * that an index is not re-used for multiple transmitted packets. The
+ * structures and functions declared in this file track the available Tx
+ * register indexes, as well as provide storage for the SKB pointers.
+ *
+ * To allow multiple ports to access the shared register block independently,
+ * the blocks are split up so that indexes are assigned to each port based on
+ * hardware logical port number.
+ */
+
+/**
+ * struct ice_tx_tstamp - Tracking for a single Tx timestamp
+ * @skb: pointer to the SKB for this timestamp request
+ * @start: jiffies when the timestamp was first requested
+ *
+ * This structure tracks a single timestamp request. The SKB pointer is
+ * provided when initiating a request. The start time is used to ensure that
+ * we discard old requests that were not fulfilled within a 2 second time
+ * window.
+ */
+struct ice_tx_tstamp {
+	struct sk_buff *skb;
+	unsigned long start;
+};
+
+/**
+ * struct ice_ptp_tx - Tracking structure for all Tx timestamp requests on a port
+ * @work: work function to handle processing of Tx timestamps
+ * @lock: lock to prevent concurrent write to in_use bitmap
+ * @tstamps: array of len to store outstanding requests
+ * @in_use: bitmap of len to indicate which slots are in use
+ * @quad: which quad the timestamps are captured in
+ * @quad_offset: offset into timestamp block of the quad to get the real index
+ * @len: length of the tstamps and in_use fields.
+ * @init: if true, the tracker is initialized;
+ */
+struct ice_ptp_tx {
+	struct kthread_work work;
+	spinlock_t lock; /* lock protecting in_use bitmap */
+	struct ice_tx_tstamp *tstamps;
+	unsigned long *in_use;
+	u8 quad;
+	u8 quad_offset;
+	u8 len;
+	u8 init;
+};
+
+/* Quad and port information for initializing timestamp blocks */
+#define INDEX_PER_QUAD			64
+#define INDEX_PER_PORT			(INDEX_PER_QUAD / ICE_PORTS_PER_QUAD)
+
+/**
+ * struct ice_ptp_port - data used to initialize an external port for PTP
+ *
+ * This structure contains PTP data related to the external ports. Currently
+ * it is used for tracking the Tx timestamps of a port. In the future this
+ * structure will also hold information for the E822 port initialization
+ * logic.
+ *
+ * @tx: Tx timestamp tracking for this port
+ */
+struct ice_ptp_port {
+	struct ice_ptp_tx tx;
+};
+
 /**
  * struct ice_ptp - data used for integrating with CONFIG_PTP_1588_CLOCK
+ * @port: data for the PHY port initialization procedure
  * @work: delayed work function for periodic tasks
  * @cached_phc_time: a cached copy of the PHC time for timestamp extension
  * @kworker: kwork thread for handling periodic work
@@ -19,6 +93,7 @@
  * @tstamp_config: hardware timestamping configuration
  */
 struct ice_ptp {
+	struct ice_ptp_port port;
 	struct kthread_delayed_work work;
 	u64 cached_phc_time;
 	struct kthread_worker *kworker;
@@ -27,6 +102,11 @@ struct ice_ptp {
 	struct hwtstamp_config tstamp_config;
 };
 
+#define __ptp_port_to_ptp(p) \
+	container_of((p), struct ice_ptp, port)
+#define ptp_port_to_pf(p) \
+	container_of(__ptp_port_to_ptp((p)), struct ice_pf, ptp)
+
 #define __ptp_info_to_ptp(i) \
 	container_of((i), struct ice_ptp, info)
 #define ptp_info_to_pf(i) \
@@ -40,6 +120,10 @@ struct ice_pf;
 int ice_ptp_set_ts_config(struct ice_pf *pf, struct ifreq *ifr);
 int ice_ptp_get_ts_config(struct ice_pf *pf, struct ifreq *ifr);
 int ice_get_ptp_clock_index(struct ice_pf *pf);
+
+s8 ice_ptp_request_ts(struct ice_ptp_tx *tx, struct sk_buff *skb);
+void ice_ptp_process_ts(struct ice_pf *pf);
+
 void
 ice_ptp_rx_hwtstamp(struct ice_ring *rx_ring,
 		    union ice_32b_rx_flex_desc *rx_desc, struct sk_buff *skb);
@@ -61,6 +145,13 @@ static inline int ice_get_ptp_clock_index(struct ice_pf *pf)
 	return -1;
 }
 
+static inline
+ice_ptp_request_ts(struct ice_ptp_tx *tx, struct sk_buff *skb)
+{
+	return -1;
+}
+
+static inline void ice_ptp_process_ts(struct ice_pf *pf) { }
 static inline void
 ice_ptp_rx_hwtstamp(struct ice_ring *rx_ring,
 		    union ice_32b_rx_flex_desc *rx_desc, struct sk_buff *skb) { }