sfc: support Medford2 frequency adjustment format

Support increased precision frequency adjustment format (FP44) used
 by Medford2 adapters.

Signed-off-by: Laurence Evans <levans@solarflare.com>
Signed-off-by: Edward Cree <ecree@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/ethernet/sfc/ptp.c b/drivers/net/ethernet/sfc/ptp.c
index 196b0768b2f2fdac88ddf5f49ce60ca4d5d350b5..433d29d6bc95af280c89783e5c089b645fefad37 100644 (file)
--- a/drivers/net/ethernet/sfc/ptp.c
+++ b/drivers/net/ethernet/sfc/ptp.c
@@ -149,18 +149,14 @@ enum ptp_packet_state {
 /* Maximum parts-per-billion adjustment that is acceptable */
 #define MAX_PPB                        1000000
 
-/* Number of bits required to hold the above */
-#define        MAX_PPB_BITS            20
-
-/* Number of extra bits allowed when calculating fractional ns.
- * EXTRA_BITS + MC_CMD_PTP_IN_ADJUST_BITS + MAX_PPB_BITS should
- * be less than 63.
- */
-#define        PPB_EXTRA_BITS          2
-
 /* Precalculate scale word to avoid long long division at runtime */
-#define        PPB_SCALE_WORD  ((1LL << (PPB_EXTRA_BITS + MC_CMD_PTP_IN_ADJUST_BITS +\
-                       MAX_PPB_BITS)) / 1000000000LL)
+/* This is equivalent to 2^66 / 10^9. */
+#define PPB_SCALE_WORD  ((1LL << (57)) / 1953125LL)
+
+/* How much to shift down after scaling to convert to FP40 */
+#define PPB_SHIFT_FP40         26
+/* ... and FP44. */
+#define PPB_SHIFT_FP44         22
 
 #define PTP_SYNC_ATTEMPTS      4
 
@@ -261,6 +257,8 @@ struct efx_ptp_timeset {
  * @evt_code: Last event code
  * @start: Address at which MC indicates ready for synchronisation
  * @host_time_pps: Host time at last PPS
+ * @adjfreq_ppb_shift: Shift required to convert scaled parts-per-billion
+ * frequency adjustment into a fixed point fractional nanosecond format.
  * @current_adjfreq: Current ppb adjustment.
  * @phc_clock: Pointer to registered phc device (if primary function)
  * @phc_clock_info: Registration structure for phc device
@@ -310,6 +308,7 @@ struct efx_ptp_data {
                unsigned int sync_event_minor_shift;
        } nic_time;
        unsigned int min_synchronisation_ns;
+       unsigned int capabilities;
        struct {
                s32 ptp_tx;
                s32 ptp_rx;
@@ -323,6 +322,7 @@ struct efx_ptp_data {
        int evt_code;
        struct efx_buffer start;
        struct pps_event_time host_time_pps;
+       unsigned int adjfreq_ppb_shift;
        s64 current_adjfreq;
        struct ptp_clock *phc_clock;
        struct ptp_clock_info phc_clock_info;
@@ -676,6 +676,22 @@ static int efx_ptp_get_attributes(struct efx_nic *efx)
        else
                ptp->min_synchronisation_ns = DEFAULT_MIN_SYNCHRONISATION_NS;
 
+       if (rc == 0 &&
+           out_len >= MC_CMD_PTP_OUT_GET_ATTRIBUTES_LEN)
+               ptp->capabilities = MCDI_DWORD(outbuf,
+                                       PTP_OUT_GET_ATTRIBUTES_CAPABILITIES);
+       else
+               ptp->capabilities = 0;
+
+       /* Set up the shift for conversion between frequency
+        * adjustments in parts-per-billion and the fixed-point
+        * fractional ns format that the adapter uses.
+        */
+       if (ptp->capabilities & (1 << MC_CMD_PTP_OUT_GET_ATTRIBUTES_FP44_FREQ_ADJ_LBN))
+               ptp->adjfreq_ppb_shift = PPB_SHIFT_FP44;
+       else
+               ptp->adjfreq_ppb_shift = PPB_SHIFT_FP40;
+
        return 0;
 }
 
@@ -2027,9 +2043,10 @@ static int efx_phc_adjfreq(struct ptp_clock_info *ptp, s32 delta)
        else if (delta < -MAX_PPB)
                delta = -MAX_PPB;
 
-       /* Convert ppb to fixed point ns. */
-       adjustment_ns = (((s64)delta * PPB_SCALE_WORD) >>
-                        (PPB_EXTRA_BITS + MAX_PPB_BITS));
+       /* Convert ppb to fixed point ns taking care to round correctly. */
+       adjustment_ns = ((s64)delta * PPB_SCALE_WORD +
+                        (1 << (ptp_data->adjfreq_ppb_shift - 1))) >>
+                       ptp_data->adjfreq_ppb_shift;
 
        MCDI_SET_DWORD(inadj, PTP_IN_OP, MC_CMD_PTP_OP_ADJUST);
        MCDI_SET_DWORD(inadj, PTP_IN_PERIPH_ID, 0);