Re: [PATCH 7/9] net: ethernet: ti: cpts: calc mult and shift from refclk freq

@@ -35,6 +33,8 @@ Optional properties:
 			  For example in dra72x-evm, pcf gpio has to be
 			  driven low so that cpsw slave 0 and phy data
 			  lines are connected via mux.
+- cpts_clock_mult	: Numerator to convert input clock ticks into nanoseconds
+- cpts_clock_shift	: Denominator to convert input clock ticks into nanoseconds

diff --git a/drivers/net/ethernet/ti/cpts.c b/drivers/net/ethernet/ti/cpts.c
index ff8bb85..8046a21 100644
--- a/drivers/net/ethernet/ti/cpts.c
+++ b/drivers/net/ethernet/ti/cpts.c

@@ -418,18 +418,60 @@ void cpts_unregister(struct cpts *cpts)
 	clk_disable(cpts->refclk);
 }
 
+static void cpts_calc_mult_shift(struct cpts *cpts)
+{
+	u64 maxsec;
+	u32 freq;
+	u32 mult;
+	u32 shift;
+	u64 ns;
+	u64 frac;

+	if (cpts->cc_mult || cpts->cc.shift)
+		return;
+
+	freq = clk_get_rate(cpts->refclk);
+
+	/* Calc the maximum number of seconds which we can run before
+	 * wrapping around.
+	 */
+	maxsec = cpts->cc.mask;
+	do_div(maxsec, freq);
+	if (!maxsec)
+		maxsec = 1;
+	else if (maxsec > 600 && cpts->cc.mask > UINT_MAX)
+		maxsec = 600;
+
+	clocks_calc_mult_shift(&mult, &shift, freq, NSEC_PER_SEC, maxsec);
+
+	cpts->cc_mult = mult;
+	cpts->cc.mult = mult;
+	cpts->cc.shift = shift;
+	/* Check calculations and inform if not precise */

+	frac = 0;
+	ns = cyclecounter_cyc2ns(&cpts->cc, freq, cpts->cc.mask, &frac);
+
+	dev_info(cpts->dev,
+		 "CPTS: ref_clk_freq:%u calc_mult:%u calc_shift:%u error:%lld nsec/sec\n",
+		 freq, cpts->cc_mult, cpts->cc.shift, (ns - NSEC_PER_SEC));
+}
+