From 428951161b8ab73d547c8915dcfc5fa6f10012a8 Mon Sep 17 00:00:00 2001 From: Ulrik De Bie Date: Wed, 23 Nov 2016 21:11:04 +0100 Subject: [PATCH] ptp: gianfar: Use high resolution frequency method. This patch depends on commit d8d263541913 ("ptp: Introduce a high resolution frequency adjustment method.") The gianfar devices offer a frequency resolution of about 0.46 ppb (depends on actual value of tmr_add, for the calculation assumed 0x80000000). This patch lets users of the device benefit from the increased frequency resolution when tuning the clock. Thanks to the rounding the maximum error between the requested frequency and the applied frequency will then be about 0.23 ppb. Tested on a v3.3.8 kernel on a real gianfar device. Verified compilation on net-next (currently at v4.9-rc5). Signed-off-by: Ulrik De Bie Signed-off-by: David S. Miller --- drivers/net/ethernet/freescale/gianfar_ptp.c | 21 ++++++++++++-------- 1 file changed, 13 insertions(+), 8 deletions(-) diff --git a/drivers/net/ethernet/freescale/gianfar_ptp.c b/drivers/net/ethernet/freescale/gianfar_ptp.c index 3e8d1fffe34e..721be13081f9 100644 --- a/drivers/net/ethernet/freescale/gianfar_ptp.c +++ b/drivers/net/ethernet/freescale/gianfar_ptp.c @@ -280,21 +280,26 @@ static irqreturn_t isr(int irq, void *priv) * PTP clock operations */ -static int ptp_gianfar_adjfreq(struct ptp_clock_info *ptp, s32 ppb) +static int ptp_gianfar_adjfine(struct ptp_clock_info *ptp, long scaled_ppm) { - u64 adj; - u32 diff, tmr_add; + u64 adj, diff; + u32 tmr_add; int neg_adj = 0; struct etsects *etsects = container_of(ptp, struct etsects, caps); - if (ppb < 0) { + if (scaled_ppm < 0) { neg_adj = 1; - ppb = -ppb; + scaled_ppm = -scaled_ppm; } tmr_add = etsects->tmr_add; adj = tmr_add; - adj *= ppb; - diff = div_u64(adj, 1000000000ULL); + + /* calculate diff as adj*(scaled_ppm/65536)/1000000 + * and round() to the nearest integer + */ + adj *= scaled_ppm; + diff = div_u64(adj, 8000000); + diff = (diff >> 13) + ((diff >> 12) & 1); tmr_add = neg_adj ? tmr_add - diff : tmr_add + diff; @@ -415,7 +420,7 @@ static struct ptp_clock_info ptp_gianfar_caps = { .n_per_out = 0, .n_pins = 0, .pps = 1, - .adjfreq = ptp_gianfar_adjfreq, + .adjfine = ptp_gianfar_adjfine, .adjtime = ptp_gianfar_adjtime, .gettime64 = ptp_gianfar_gettime, .settime64 = ptp_gianfar_settime, -- 2.20.1