netdev - [PATCH v3 7/9] ptp: ptp_clockmatrix: Add .getmaxphase ptp_clock

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Date: Mon, 12 Jun 2023 14:14:58 -0700
From: Rahul Rameshbabu <rrameshbabu@...dia.com>
To: netdev@...r.kernel.org
Cc: Gal Pressman <gal@...dia.com>,
	Saeed Mahameed <saeed@...nel.org>,
	Tariq Toukan <tariqt@...dia.com>,
	Jakub Kicinski <kuba@...nel.org>,
	Richard Cochran <richardcochran@...il.com>,
	Jacob Keller <jacob.e.keller@...el.com>,
	Paolo Abeni <pabeni@...hat.com>,
	"David S. Miller" <davem@...emloft.net>,
	Rahul Rameshbabu <rrameshbabu@...dia.com>,
	Vincent Cheng <vincent.cheng.xh@...esas.com>
Subject: [PATCH v3 7/9] ptp: ptp_clockmatrix: Add .getmaxphase ptp_clock_info callback

Advertise the maximum offset the .adjphase callback is capable of
supporting in nanoseconds for IDT ClockMatrix devices. Depend on
ptp_clock_adjtime for handling out-of-range offsets. ptp_clock_adjtime
returns -ERANGE instead of clamping out-of-range offsets.

Cc: Richard Cochran <richardcochran@...il.com>
Cc: Vincent Cheng <vincent.cheng.xh@...esas.com>
Signed-off-by: Rahul Rameshbabu <rrameshbabu@...dia.com>
---

Notes:
    Changes:
    
      v3->v2:
        * Add information about returning -ERANGE instead of clamping
          out-of-range offsets.
    
          Link: https://lore.kernel.org/netdev/13b7315446390d3a78d8f508937354f12778b68e.camel@redhat.com/

 drivers/ptp/ptp_clockmatrix.c | 36 +++++++++++++++++------------------
 drivers/ptp/ptp_clockmatrix.h |  2 +-
 2 files changed, 18 insertions(+), 20 deletions(-)

diff --git a/drivers/ptp/ptp_clockmatrix.c b/drivers/ptp/ptp_clockmatrix.c
index c9d451bf89e2..f6f9d4adce04 100644
--- a/drivers/ptp/ptp_clockmatrix.c
+++ b/drivers/ptp/ptp_clockmatrix.c
@@ -1692,14 +1692,23 @@ static int initialize_dco_operating_mode(struct idtcm_channel *channel)
 /* PTP Hardware Clock interface */
 
 /*
- * Maximum absolute value for write phase offset in picoseconds
- *
- * @channel:  channel
- * @delta_ns: delta in nanoseconds
+ * Maximum absolute value for write phase offset in nanoseconds
  *
  * Destination signed register is 32-bit register in resolution of 50ps
  *
- * 0x7fffffff * 50 =  2147483647 * 50 = 107374182350
+ * 0x7fffffff * 50 =  2147483647 * 50 = 107374182350 ps
+ * Represent 107374182350 ps as 107374182 ns
+ */
+static s32 idtcm_getmaxphase(struct ptp_clock_info *ptp __always_unused)
+{
+	return MAX_ABS_WRITE_PHASE_NANOSECONDS;
+}
+
+/*
+ * Internal function for implementing support for write phase offset
+ *
+ * @channel:  channel
+ * @delta_ns: delta in nanoseconds
  */
 static int _idtcm_adjphase(struct idtcm_channel *channel, s32 delta_ns)
 {
@@ -1708,7 +1717,6 @@ static int _idtcm_adjphase(struct idtcm_channel *channel, s32 delta_ns)
 	u8 i;
 	u8 buf[4] = {0};
 	s32 phase_50ps;
-	s64 offset_ps;
 
 	if (channel->mode != PTP_PLL_MODE_WRITE_PHASE) {
 		err = channel->configure_write_phase(channel);
@@ -1716,19 +1724,7 @@ static int _idtcm_adjphase(struct idtcm_channel *channel, s32 delta_ns)
 			return err;
 	}
 
-	offset_ps = (s64)delta_ns * 1000;
-
-	/*
-	 * Check for 32-bit signed max * 50:
-	 *
-	 * 0x7fffffff * 50 =  2147483647 * 50 = 107374182350
-	 */
-	if (offset_ps > MAX_ABS_WRITE_PHASE_PICOSECONDS)
-		offset_ps = MAX_ABS_WRITE_PHASE_PICOSECONDS;
-	else if (offset_ps < -MAX_ABS_WRITE_PHASE_PICOSECONDS)
-		offset_ps = -MAX_ABS_WRITE_PHASE_PICOSECONDS;
-
-	phase_50ps = div_s64(offset_ps, 50);
+	phase_50ps = div_s64((s64)delta_ns * 1000, 50);
 
 	for (i = 0; i < 4; i++) {
 		buf[i] = phase_50ps & 0xff;
@@ -2048,6 +2044,7 @@ static const struct ptp_clock_info idtcm_caps = {
 	.n_ext_ts	= MAX_TOD,
 	.n_pins		= MAX_REF_CLK,
 	.adjphase	= &idtcm_adjphase,
+	.getmaxphase	= &idtcm_getmaxphase,
 	.adjfine	= &idtcm_adjfine,
 	.adjtime	= &idtcm_adjtime,
 	.gettime64	= &idtcm_gettime,
@@ -2064,6 +2061,7 @@ static const struct ptp_clock_info idtcm_caps_deprecated = {
 	.n_ext_ts	= MAX_TOD,
 	.n_pins		= MAX_REF_CLK,
 	.adjphase	= &idtcm_adjphase,
+	.getmaxphase    = &idtcm_getmaxphase,
 	.adjfine	= &idtcm_adjfine,
 	.adjtime	= &idtcm_adjtime_deprecated,
 	.gettime64	= &idtcm_gettime,
diff --git a/drivers/ptp/ptp_clockmatrix.h b/drivers/ptp/ptp_clockmatrix.h
index bf1e49409844..7c17c4f7f573 100644
--- a/drivers/ptp/ptp_clockmatrix.h
+++ b/drivers/ptp/ptp_clockmatrix.h
@@ -18,7 +18,7 @@
 #define MAX_PLL		(8)
 #define MAX_REF_CLK	(16)
 
-#define MAX_ABS_WRITE_PHASE_PICOSECONDS (107374182350LL)
+#define MAX_ABS_WRITE_PHASE_NANOSECONDS (107374182L)
 
 #define TOD_MASK_ADDR		(0xFFA5)
 #define DEFAULT_TOD_MASK	(0x04)
-- 
2.40.1