diff options
| author | Yangbo Lu <yangbo.lu@nxp.com> | 2021-03-23 16:02:29 +0800 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2021-03-24 12:10:03 -0700 |
| commit | f51d7bf1dbe5522c51c93fe8faa5f4abbdf339cd (patch) | |
| tree | 9bf2cbf2895eef9c81e4ec338c0dd9fa37b08812 | |
| parent | 6ab4c3117aec4e08007d9e971fa4133e1de1082d (diff) | |
ptp_qoriq: fix overflow in ptp_qoriq_adjfine() u64 calcalation
Current calculation for diff of TMR_ADD register value may have
64-bit overflow in this code line, when long type scaled_ppm is
large.
adj *= scaled_ppm;
This patch is to resolve it by using mul_u64_u64_div_u64().
Signed-off-by: Yangbo Lu <yangbo.lu@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | drivers/ptp/ptp_qoriq.c | 13 |
1 files changed, 7 insertions, 6 deletions
diff --git a/drivers/ptp/ptp_qoriq.c b/drivers/ptp/ptp_qoriq.c index beb5f74944cd..08f4cf0ad9e3 100644 --- a/drivers/ptp/ptp_qoriq.c +++ b/drivers/ptp/ptp_qoriq.c @@ -189,15 +189,16 @@ int ptp_qoriq_adjfine(struct ptp_clock_info *ptp, long scaled_ppm) tmr_add = ptp_qoriq->tmr_add; adj = tmr_add; - /* calculate diff as adj*(scaled_ppm/65536)/1000000 - * and round() to the nearest integer + /* + * Calculate diff and round() to the nearest integer + * + * diff = adj * (ppb / 1000000000) + * = adj * scaled_ppm / 65536000000 */ - adj *= scaled_ppm; - diff = div_u64(adj, 8000000); - diff = (diff >> 13) + ((diff >> 12) & 1); + diff = mul_u64_u64_div_u64(adj, scaled_ppm, 32768000000); + diff = DIV64_U64_ROUND_UP(diff, 2); tmr_add = neg_adj ? tmr_add - diff : tmr_add + diff; - ptp_qoriq->write(®s->ctrl_regs->tmr_add, tmr_add); return 0; |