Merge branch 'ptp-adjfine'

Jacob Keller says:

====================
ptp: convert drivers to .adjfine

Many drivers implementing PTP have not yet migrated to the new .adjfine
frequency adjustment implementation.

A handful of these drivers use hardware with a simple increment value which
is adjusted by multiplying by the adjustment factor and then dividing by
1 billion. This calculation is very easy to convert to .adjfine, by simply
updating the divisor.

Introduce new helper functions, diff_by_scaled_ppm and adjust_by_scaled_ppm
which perform the most common calculations used by drivers for this purpose.

The adjust_by_scaled_ppm takes the base increment and scaled PPM value, and
calculates the new increment to use.

A few drivers need the difference and direction rather than a raw increment
value. The diff_by_scaled_ppm calculates the difference and returns true if
it should be a subtraction, false otherwise. This most closely aligns with
existing driver implementations.

I previously submitted v1 of this series at [1], and got some feedback only
on a handful of drivers. In the interest of merging the changes which have
received feedback, I've dropped the following drivers out of this send:

 * ptp_phc
 * ptp_ipx46x
 * tg3
 * hclge
 * stmac
 * cpts

I plan to submit those drivers changes again at a later date. As before,
there are some drivers which are not trivial to convert to the new helper
functions. While they may be able to work, their implementation is different
and I lack the hardware or datasheets to determine what the correct
implementation would be.

* drivers/net/ethernet/broadcom/bnx2x
* drivers/net/ethernet/broadcom/bnxt
* drivers/net/ethernet/cavium/liquidio
* drivers/net/ethernet/chelsio/cxgb4
* drivers/net/ethernet/freescale
* drivers/net/ethernet/qlogic/qed
* drivers/net/ethernet/qlogic/qede
* drivers/net/ethernet/sfc
* drivers/net/ethernet/sfc/siena
* drivers/net/ethernet/ti/am65-cpts.c
* drivers/ptp/ptp_dte.c

My end goal is to drop the .adjfreq implementation entirely, and to that end
I plan on modifying these drivers in the future to directly use
scaled_ppm_to_ppb as the simplest method to convert them.

Changes since v2:
* Rebased to allow landing in 6.2
* Added Richard's Acked-by

Cc: "K. Y. Srinivasan" <kys@microsoft.com>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: Stephen Hemminger <sthemmin@microsoft.com>
Cc: Wei Liu <wei.liu@kernel.org>
Cc: Dexuan Cui <decui@microsoft.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Shyam Sundar S K <Shyam-sundar.S-k@amd.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: Siva Reddy Kallam <siva.kallam@broadcom.com>
Cc: Prashant Sreedharan <prashant@broadcom.com>
Cc: Michael Chan <mchan@broadcom.com>
Cc: Yisen Zhuang <yisen.zhuang@huawei.com>
Cc: Salil Mehta <salil.mehta@huawei.com>
Cc: Jesse Brandeburg <jesse.brandeburg@intel.com>
Cc: Tony Nguyen <anthony.l.nguyen@intel.com>
Cc: Tariq Toukan <tariqt@nvidia.com>
Cc: Saeed Mahameed <saeedm@nvidia.com>
Cc: Leon Romanovsky <leon@kernel.org>
Cc: Bryan Whitehead <bryan.whitehead@microchip.com>
Cc: Sergey Shtylyov <s.shtylyov@omp.ru>
Cc: Giuseppe Cavallaro <peppe.cavallaro@st.com>
Cc: Alexandre Torgue <alexandre.torgue@foss.st.com>
Cc: Jose Abreu <joabreu@synopsys.com>
Cc: Maxime Coquelin <mcoquelin.stm32@gmail.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Vivek Thampi <vithampi@vmware.com>
Cc: VMware PV-Drivers Reviewers <pv-drivers@vmware.com>
Cc: Jie Wang <wangjie125@huawei.com>
Cc: Jacob Keller <jacob.e.keller@intel.com>
Cc: Guangbin Huang <huangguangbin2@huawei.com>
Cc: Eran Ben Elisha <eranbe@nvidia.com>
Cc: Aya Levin <ayal@nvidia.com>
Cc: Cai Huoqing <cai.huoqing@linux.dev>
Cc: Biju Das <biju.das.jz@bp.renesas.com>
Cc: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Cc: Phil Edworthy <phil.edworthy@renesas.com>
Cc: Jiasheng Jiang <jiasheng@iscas.ac.cn>
Cc: "Gustavo A. R. Silva" <gustavoars@kernel.org>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Wan Jiabing <wanjiabing@vivo.com>
Cc: Lv Ruyi <lv.ruyi@zte.com.cn>
Cc: Arnd Bergmann <arnd@arndb.de>
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 53 insertions, 0 deletions

diff --git a/include/linux/ptp_clock_kernel.h b/include/linux/ptp_clock_kernel.h
index 92b44161408e..f4781c5766d6 100644
--- a/include/linux/ptp_clock_kernel.h
+++ b/include/linux/ptp_clock_kernel.h
@@ -45,6 +45,8 @@ struct system_device_crosststamp;
 
 /**
  * struct ptp_system_timestamp - system time corresponding to a PHC timestamp
+ * @pre_ts: system timestamp before capturing PHC
+ * @post_ts: system timestamp after capturing PHC
  */
 struct ptp_system_timestamp {
 	struct timespec64 pre_ts;
@@ -246,6 +248,52 @@ static inline long scaled_ppm_to_ppb(long ppm)
 	return (long)ppb;
 }
 
+/**
+ * diff_by_scaled_ppm - Calculate difference using scaled ppm
+ * @base: the base increment value to adjust
+ * @scaled_ppm: scaled parts per million to adjust by
+ * @diff: on return, the absolute value of calculated diff
+ *
+ * Calculate the difference to adjust the base increment using scaled parts
+ * per million.
+ *
+ * Use mul_u64_u64_div_u64 to perform the difference calculation in avoid
+ * possible overflow.
+ *
+ * Returns: true if scaled_ppm is negative, false otherwise
+ */
+static inline bool diff_by_scaled_ppm(u64 base, long scaled_ppm, u64 *diff)
+{
+	bool negative = false;
+
+	if (scaled_ppm < 0) {
+		negative = true;
+		scaled_ppm = -scaled_ppm;
+	}
+
+	*diff = mul_u64_u64_div_u64(base, (u64)scaled_ppm, 1000000ULL << 16);
+
+	return negative;
+}
+
+/**
+ * adjust_by_scaled_ppm - Adjust a base increment by scaled parts per million
+ * @base: the base increment value to adjust
+ * @scaled_ppm: scaled parts per million frequency adjustment
+ *
+ * Helper function which calculates a new increment value based on the
+ * requested scaled parts per million adjustment.
+ */
+static inline u64 adjust_by_scaled_ppm(u64 base, long scaled_ppm)
+{
+	u64 diff;
+
+	if (diff_by_scaled_ppm(base, scaled_ppm, &diff))
+		return base - diff;
+
+	return base + diff;
+}
+
 #if IS_ENABLED(CONFIG_PTP_1588_CLOCK)
 
 /**
@@ -316,6 +364,11 @@ int ptp_find_pin(struct ptp_clock *ptp,
  * should most likely call ptp_find_pin() directly from their
  * ptp_clock_info::enable() method.
  *
+* @ptp:    The clock obtained from ptp_clock_register().
+* @func:   One of the ptp_pin_function enumerated values.
+* @chan:   The particular functional channel to find.
+* Return:  Pin index in the range of zero to ptp_clock_caps.n_pins - 1,
+*          or -1 if the auxiliary function cannot be found.
  */
 
 int ptp_find_pin_unlocked(struct ptp_clock *ptp,