sfc: Add support for SFC9100 timestamp format

The clock minor tick on the SFC9100 family is 2^-27 s, not 1 ns.
There are also various pipeline delays which we need to correct for
when interpreting timestamps.

We query the firmware for the clock format and corrections at run-time.

[bwh: Combined and rebased several changes]
Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>

drivers/net/ethernet/sfc/ptp.c

@@ -62,7 +62,7 @@
 #define	SYNCHRONISATION_GRANULARITY_NS	200
 
 /* Minimum permitted length of a (corrected) synchronisation time */
-#define	MIN_SYNCHRONISATION_NS		120
+#define	DEFAULT_MIN_SYNCHRONISATION_NS	120
 
 /* Maximum permitted length of a (corrected) synchronisation time */
 #define	MAX_SYNCHRONISATION_NS		1000
@@ -195,20 +195,20 @@ struct efx_ptp_event_rx {
 /**
  * struct efx_ptp_timeset - Synchronisation between host and MC
  * @host_start: Host time immediately before hardware timestamp taken
- * @seconds: Hardware timestamp, seconds
- * @nanoseconds: Hardware timestamp, nanoseconds
+ * @major: Hardware timestamp, major
+ * @minor: Hardware timestamp, minor
  * @host_end: Host time immediately after hardware timestamp taken
- * @waitns: Number of nanoseconds between hardware timestamp being read and
+ * @wait: Number of NIC clock ticks between hardware timestamp being read and
  *          host end time being seen
  * @window: Difference of host_end and host_start
  * @valid: Whether this timeset is valid
  */
 struct efx_ptp_timeset {
 	u32 host_start;
-	u32 seconds;
-	u32 nanoseconds;
+	u32 major;
+	u32 minor;
 	u32 host_end;
-	u32 waitns;
+	u32 wait;
 	u32 window;	/* Derived: end - start, allowing for wrap */
 };
 
@@ -232,6 +232,14 @@ struct efx_ptp_timeset {
  * @config: Current timestamp configuration
  * @enabled: PTP operation enabled
  * @mode: Mode in which PTP operating (PTP version)
+ * @time_format: Time format supported by this NIC
+ * @ns_to_nic_time: Function to convert from scalar nanoseconds to NIC time
+ * @nic_to_kernel_time: Function to convert from NIC to kernel time
+ * @min_synchronisation_ns: Minimum acceptable corrected sync window
+ * @ts_corrections.tx: Required driver correction of transmit timestamps
+ * @ts_corrections.rx: Required driver correction of receive timestamps
+ * @ts_corrections.pps_out: PPS output error (information only)
+ * @ts_corrections.pps_in: Required driver correction of PPS input timestamps
  * @evt_frags: Partly assembled PTP events
  * @evt_frag_idx: Current fragment number
  * @evt_code: Last event code
@@ -266,6 +274,17 @@ struct efx_ptp_data {
 	struct hwtstamp_config config;
 	bool enabled;
 	unsigned int mode;
+	unsigned int time_format;
+	void (*ns_to_nic_time)(s64 ns, u32 *nic_major, u32 *nic_minor);
+	ktime_t (*nic_to_kernel_time)(u32 nic_major, u32 nic_minor,
+				      s32 correction);
+	unsigned int min_synchronisation_ns;
+	struct {
+		s32 tx;
+		s32 rx;
+		s32 pps_out;
+		s32 pps_in;
+	} ts_corrections;
 	efx_qword_t evt_frags[MAX_EVENT_FRAGS];
 	int evt_frag_idx;
 	int evt_code;
@@ -290,6 +309,167 @@ static int efx_phc_settime(struct ptp_clock_info *ptp,
 static int efx_phc_enable(struct ptp_clock_info *ptp,
 			  struct ptp_clock_request *request, int on);
 
+/* For Siena platforms NIC time is s and ns */
+static void efx_ptp_ns_to_s_ns(s64 ns, u32 *nic_major, u32 *nic_minor)
+{
+	struct timespec ts = ns_to_timespec(ns);
+	*nic_major = ts.tv_sec;
+	*nic_minor = ts.tv_nsec;
+}
+
+static ktime_t efx_ptp_s_ns_to_ktime(u32 nic_major, u32 nic_minor,
+				     s32 correction)
+{
+	ktime_t kt = ktime_set(nic_major, nic_minor);
+	if (correction >= 0)
+		kt = ktime_add_ns(kt, (u64)correction);
+	else
+		kt = ktime_sub_ns(kt, (u64)-correction);
+	return kt;
+}
+
+/* To convert from s27 format to ns we multiply then divide by a power of 2.
+ * For the conversion from ns to s27, the operation is also converted to a
+ * multiply and shift.
+ */
+#define S27_TO_NS_SHIFT	(27)
+#define NS_TO_S27_MULT	(((1ULL << 63) + NSEC_PER_SEC / 2) / NSEC_PER_SEC)
+#define NS_TO_S27_SHIFT	(63 - S27_TO_NS_SHIFT)
+#define S27_MINOR_MAX	(1 << S27_TO_NS_SHIFT)
+
+/* For Huntington platforms NIC time is in seconds and fractions of a second
+ * where the minor register only uses 27 bits in units of 2^-27s.
+ */
+static void efx_ptp_ns_to_s27(s64 ns, u32 *nic_major, u32 *nic_minor)
+{
+	struct timespec ts = ns_to_timespec(ns);
+	u32 maj = ts.tv_sec;
+	u32 min = (u32)(((u64)ts.tv_nsec * NS_TO_S27_MULT +
+			 (1ULL << (NS_TO_S27_SHIFT - 1))) >> NS_TO_S27_SHIFT);
+
+	/* The conversion can result in the minor value exceeding the maximum.
+	 * In this case, round up to the next second.
+	 */
+	if (min >= S27_MINOR_MAX) {
+		min -= S27_MINOR_MAX;
+		maj++;
+	}
+
+	*nic_major = maj;
+	*nic_minor = min;
+}
+
+static ktime_t efx_ptp_s27_to_ktime(u32 nic_major, u32 nic_minor,
+				    s32 correction)
+{
+	u32 ns;
+
+	/* Apply the correction and deal with carry */
+	nic_minor += correction;
+	if ((s32)nic_minor < 0) {
+		nic_minor += S27_MINOR_MAX;
+		nic_major--;
+	} else if (nic_minor >= S27_MINOR_MAX) {
+		nic_minor -= S27_MINOR_MAX;
+		nic_major++;
+	}
+
+	ns = (u32)(((u64)nic_minor * NSEC_PER_SEC +
+		    (1ULL << (S27_TO_NS_SHIFT - 1))) >> S27_TO_NS_SHIFT);
+
+	return ktime_set(nic_major, ns);
+}
+
+/* Get PTP attributes and set up time conversions */
+static int efx_ptp_get_attributes(struct efx_nic *efx)
+{
+	MCDI_DECLARE_BUF(inbuf, MC_CMD_PTP_IN_GET_ATTRIBUTES_LEN);
+	MCDI_DECLARE_BUF(outbuf, MC_CMD_PTP_OUT_GET_ATTRIBUTES_LEN);
+	struct efx_ptp_data *ptp = efx->ptp_data;
+	int rc;
+	u32 fmt;
+	size_t out_len;
+
+	/* Get the PTP attributes. If the NIC doesn't support the operation we
+	 * use the default format for compatibility with older NICs i.e.
+	 * seconds and nanoseconds.
+	 */
+	MCDI_SET_DWORD(inbuf, PTP_IN_OP, MC_CMD_PTP_OP_GET_ATTRIBUTES);
+	MCDI_SET_DWORD(inbuf, PTP_IN_PERIPH_ID, 0);
+	rc = efx_mcdi_rpc(efx, MC_CMD_PTP, inbuf, sizeof(inbuf),
+			  outbuf, sizeof(outbuf), &out_len);
+	if (rc == 0)
+		fmt = MCDI_DWORD(outbuf, PTP_OUT_GET_ATTRIBUTES_TIME_FORMAT);
+	else if (rc == -EINVAL)
+		fmt = MC_CMD_PTP_OUT_GET_ATTRIBUTES_SECONDS_NANOSECONDS;
+	else
+		return rc;
+
+	if (fmt == MC_CMD_PTP_OUT_GET_ATTRIBUTES_SECONDS_27FRACTION) {
+		ptp->ns_to_nic_time = efx_ptp_ns_to_s27;
+		ptp->nic_to_kernel_time = efx_ptp_s27_to_ktime;
+	} else if (fmt == MC_CMD_PTP_OUT_GET_ATTRIBUTES_SECONDS_NANOSECONDS) {
+		ptp->ns_to_nic_time = efx_ptp_ns_to_s_ns;
+		ptp->nic_to_kernel_time = efx_ptp_s_ns_to_ktime;
+	} else {
+		return -ERANGE;
+	}
+
+	ptp->time_format = fmt;
+
+	/* MC_CMD_PTP_OP_GET_ATTRIBUTES is an extended version of an older
+	 * operation MC_CMD_PTP_OP_GET_TIME_FORMAT that also returns a value
+	 * to use for the minimum acceptable corrected synchronization window.
+	 * If we have the extra information store it. For older firmware that
+	 * does not implement the extended command use the default value.
+	 */
+	if (rc == 0 && out_len >= MC_CMD_PTP_OUT_GET_ATTRIBUTES_LEN)
+		ptp->min_synchronisation_ns =
+			MCDI_DWORD(outbuf,
+				   PTP_OUT_GET_ATTRIBUTES_SYNC_WINDOW_MIN);
+	else
+		ptp->min_synchronisation_ns = DEFAULT_MIN_SYNCHRONISATION_NS;
+
+	return 0;
+}
+
+/* Get PTP timestamp corrections */
+static int efx_ptp_get_timestamp_corrections(struct efx_nic *efx)
+{
+	MCDI_DECLARE_BUF(inbuf, MC_CMD_PTP_IN_GET_TIMESTAMP_CORRECTIONS_LEN);
+	MCDI_DECLARE_BUF(outbuf, MC_CMD_PTP_OUT_GET_TIMESTAMP_CORRECTIONS_LEN);
+	int rc;
+
+	/* Get the timestamp corrections from the NIC. If this operation is
+	 * not supported (older NICs) then no correction is required.
+	 */
+	MCDI_SET_DWORD(inbuf, PTP_IN_OP,
+		       MC_CMD_PTP_OP_GET_TIMESTAMP_CORRECTIONS);
+	MCDI_SET_DWORD(inbuf, PTP_IN_PERIPH_ID, 0);
+
+	rc = efx_mcdi_rpc(efx, MC_CMD_PTP, inbuf, sizeof(inbuf),
+			  outbuf, sizeof(outbuf), NULL);
+	if (rc == 0) {
+		efx->ptp_data->ts_corrections.tx = MCDI_DWORD(outbuf,
+			PTP_OUT_GET_TIMESTAMP_CORRECTIONS_TRANSMIT);
+		efx->ptp_data->ts_corrections.rx = MCDI_DWORD(outbuf,
+			PTP_OUT_GET_TIMESTAMP_CORRECTIONS_RECEIVE);
+		efx->ptp_data->ts_corrections.pps_out = MCDI_DWORD(outbuf,
+			PTP_OUT_GET_TIMESTAMP_CORRECTIONS_PPS_OUT);
+		efx->ptp_data->ts_corrections.pps_in = MCDI_DWORD(outbuf,
+			PTP_OUT_GET_TIMESTAMP_CORRECTIONS_PPS_IN);
+	} else if (rc == -EINVAL) {
+		efx->ptp_data->ts_corrections.tx = 0;
+		efx->ptp_data->ts_corrections.rx = 0;
+		efx->ptp_data->ts_corrections.pps_out = 0;
+		efx->ptp_data->ts_corrections.pps_in = 0;
+	} else {
+		return rc;
+	}
+
+	return 0;
+}
+
 /* Enable MCDI PTP support. */
 static int efx_ptp_enable(struct efx_nic *efx)
 {
@@ -402,11 +582,10 @@ static void efx_ptp_read_timeset(MCDI_DECLARE_STRUCT_PTR(data),
 	unsigned start_ns, end_ns;
 
 	timeset->host_start = MCDI_DWORD(data, PTP_OUT_SYNCHRONIZE_HOSTSTART);
-	timeset->seconds = MCDI_DWORD(data, PTP_OUT_SYNCHRONIZE_SECONDS);
-	timeset->nanoseconds = MCDI_DWORD(data,
-					 PTP_OUT_SYNCHRONIZE_NANOSECONDS);
+	timeset->major = MCDI_DWORD(data, PTP_OUT_SYNCHRONIZE_MAJOR);
+	timeset->minor = MCDI_DWORD(data, PTP_OUT_SYNCHRONIZE_MINOR);
 	timeset->host_end = MCDI_DWORD(data, PTP_OUT_SYNCHRONIZE_HOSTEND),
-	timeset->waitns = MCDI_DWORD(data, PTP_OUT_SYNCHRONIZE_WAITNS);
+	timeset->wait = MCDI_DWORD(data, PTP_OUT_SYNCHRONIZE_WAITNS);
 
 	/* Ignore seconds */
 	start_ns = timeset->host_start & MC_NANOSECOND_MASK;
@@ -441,6 +620,7 @@ efx_ptp_process_times(struct efx_nic *efx, MCDI_DECLARE_STRUCT_PTR(synch_buf),
 	u32 last_sec;
 	u32 start_sec;
 	struct timespec delta;
+	ktime_t mc_time;
 
 	if (number_readings == 0)
 		return -EAGAIN;
@@ -452,14 +632,17 @@ efx_ptp_process_times(struct efx_nic *efx, MCDI_DECLARE_STRUCT_PTR(synch_buf),
 	 */
 	for (i = 0; i < number_readings; i++) {
 		s32 window, corrected;
+		struct timespec wait;
 
 		efx_ptp_read_timeset(
 			MCDI_ARRAY_STRUCT_PTR(synch_buf,
 					      PTP_OUT_SYNCHRONIZE_TIMESET, i),
 			&ptp->timeset[i]);
 
+		wait = ktime_to_timespec(
+			ptp->nic_to_kernel_time(0, ptp->timeset[i].wait, 0));
 		window = ptp->timeset[i].window;
-		corrected = window - ptp->timeset[i].waitns;
+		corrected = window - wait.tv_nsec;
 
 		/* We expect the uncorrected synchronization window to be at
 		 * least as large as the interval between host start and end
@@ -472,7 +655,7 @@ efx_ptp_process_times(struct efx_nic *efx, MCDI_DECLARE_STRUCT_PTR(synch_buf),
 		 */
 		if (window >= SYNCHRONISATION_GRANULARITY_NS &&
 		    corrected < MAX_SYNCHRONISATION_NS &&
-		    corrected >= MIN_SYNCHRONISATION_NS) {
+		    corrected >= ptp->min_synchronisation_ns) {
 			ngood++;
 			last_good = i;
 		}
@@ -484,9 +667,15 @@ efx_ptp_process_times(struct efx_nic *efx, MCDI_DECLARE_STRUCT_PTR(synch_buf),
 		return -EAGAIN;
 	}
 
+	/* Convert the NIC time into kernel time. No correction is required-
+	 * this time is the output of a firmware process.
+	 */
+	mc_time = ptp->nic_to_kernel_time(ptp->timeset[last_good].major,
+					  ptp->timeset[last_good].minor, 0);
+
 	/* Calculate delay from actual PPS to last_time */
-	delta.tv_nsec =
-		ptp->timeset[last_good].nanoseconds +
+	delta = ktime_to_timespec(mc_time);
+	delta.tv_nsec +=
 		last_time->ts_real.tv_nsec -
 		(ptp->timeset[last_good].host_start & MC_NANOSECOND_MASK);
 
@@ -596,9 +785,10 @@ static int efx_ptp_xmit_skb(struct efx_nic *efx, struct sk_buff *skb)
 		goto fail;
 
 	memset(&timestamps, 0, sizeof(timestamps));
-	timestamps.hwtstamp = ktime_set(
-		MCDI_DWORD(txtime, PTP_OUT_TRANSMIT_SECONDS),
-		MCDI_DWORD(txtime, PTP_OUT_TRANSMIT_NANOSECONDS));
+	timestamps.hwtstamp = ptp_data->nic_to_kernel_time(
+		MCDI_DWORD(txtime, PTP_OUT_TRANSMIT_MAJOR),
+		MCDI_DWORD(txtime, PTP_OUT_TRANSMIT_MINOR),
+		ptp_data->ts_corrections.tx);
 
 	skb_tstamp_tx(skb, &timestamps);
 
@@ -954,6 +1144,16 @@ int efx_ptp_probe(struct efx_nic *efx, struct efx_channel *channel)
 		list_add(&ptp->rx_evts[pos].link, &ptp->evt_free_list);
 	ptp->evt_overflow = false;
 
+	/* Get the NIC PTP attributes and set up time conversions */
+	rc = efx_ptp_get_attributes(efx);
+	if (rc < 0)
+		goto fail3;
+
+	/* Get the timestamp corrections */
+	rc = efx_ptp_get_timestamp_corrections(efx);
+	if (rc < 0)
+		goto fail3;
+
 	ptp->phc_clock_info = efx_phc_clock_info;
 	ptp->phc_clock = ptp_clock_register(&ptp->phc_clock_info,
 					    &efx->pci_dev->dev);
@@ -1358,9 +1558,10 @@ static void ptp_event_rx(struct efx_nic *efx, struct efx_ptp_data *ptp)
 					      MCDI_EVENT_SRC) << 8) |
 			     (EFX_QWORD_FIELD(ptp->evt_frags[0],
 					      MCDI_EVENT_SRC) << 16));
-		evt->hwtimestamp = ktime_set(
+		evt->hwtimestamp = efx->ptp_data->nic_to_kernel_time(
 			EFX_QWORD_FIELD(ptp->evt_frags[0], MCDI_EVENT_DATA),
-			EFX_QWORD_FIELD(ptp->evt_frags[1], MCDI_EVENT_DATA));
+			EFX_QWORD_FIELD(ptp->evt_frags[1], MCDI_EVENT_DATA),
+			ptp->ts_corrections.rx);
 		evt->expiry = jiffies + msecs_to_jiffies(PKT_EVENT_LIFETIME_MS);
 		list_add_tail(&evt->link, &ptp->evt_list);
 
@@ -1470,18 +1671,20 @@ static int efx_phc_adjfreq(struct ptp_clock_info *ptp, s32 delta)
 
 static int efx_phc_adjtime(struct ptp_clock_info *ptp, s64 delta)
 {
+	u32 nic_major, nic_minor;
 	struct efx_ptp_data *ptp_data = container_of(ptp,
 						     struct efx_ptp_data,
 						     phc_clock_info);
 	struct efx_nic *efx = ptp_data->efx;
-	struct timespec delta_ts = ns_to_timespec(delta);
 	MCDI_DECLARE_BUF(inbuf, MC_CMD_PTP_IN_ADJUST_LEN);
 
+	efx->ptp_data->ns_to_nic_time(delta, &nic_major, &nic_minor);
+
 	MCDI_SET_DWORD(inbuf, PTP_IN_OP, MC_CMD_PTP_OP_ADJUST);
 	MCDI_SET_DWORD(inbuf, PTP_IN_PERIPH_ID, 0);
 	MCDI_SET_QWORD(inbuf, PTP_IN_ADJUST_FREQ, ptp_data->current_adjfreq);
-	MCDI_SET_DWORD(inbuf, PTP_IN_ADJUST_SECONDS, (u32)delta_ts.tv_sec);
-	MCDI_SET_DWORD(inbuf, PTP_IN_ADJUST_NANOSECONDS, (u32)delta_ts.tv_nsec);
+	MCDI_SET_DWORD(inbuf, PTP_IN_ADJUST_MAJOR, nic_major);
+	MCDI_SET_DWORD(inbuf, PTP_IN_ADJUST_MINOR, nic_minor);
 	return efx_mcdi_rpc(efx, MC_CMD_PTP, inbuf, sizeof(inbuf),
 			    NULL, 0, NULL);
 }
@@ -1495,6 +1698,7 @@ static int efx_phc_gettime(struct ptp_clock_info *ptp, struct timespec *ts)
 	MCDI_DECLARE_BUF(inbuf, MC_CMD_PTP_IN_READ_NIC_TIME_LEN);
 	MCDI_DECLARE_BUF(outbuf, MC_CMD_PTP_OUT_READ_NIC_TIME_LEN);
 	int rc;
+	ktime_t kt;
 
 	MCDI_SET_DWORD(inbuf, PTP_IN_OP, MC_CMD_PTP_OP_READ_NIC_TIME);
 	MCDI_SET_DWORD(inbuf, PTP_IN_PERIPH_ID, 0);
@@ -1504,8 +1708,10 @@ static int efx_phc_gettime(struct ptp_clock_info *ptp, struct timespec *ts)
 	if (rc != 0)
 		return rc;
 
-	ts->tv_sec = MCDI_DWORD(outbuf, PTP_OUT_READ_NIC_TIME_SECONDS);
-	ts->tv_nsec = MCDI_DWORD(outbuf, PTP_OUT_READ_NIC_TIME_NANOSECONDS);
+	kt = ptp_data->nic_to_kernel_time(
+		MCDI_DWORD(outbuf, PTP_OUT_READ_NIC_TIME_MAJOR),
+		MCDI_DWORD(outbuf, PTP_OUT_READ_NIC_TIME_MINOR), 0);
+	*ts = ktime_to_timespec(kt);
 	return 0;
 }