From 92ca1119868abbd859c8f7a3f88143cf53561eb3 Mon Sep 17 00:00:00 2001
From: Alex Maclean <monkeh@monkeh.net>
Date: Thu, 18 Nov 2021 23:20:59 +0000
Subject: [PATCH] atsam: Fix I2C bitrate

Multiplying the desired bitrate by 4 results in half the
desired period and thus twice the desired bitrate.

Signed-off-by: Alex Maclean <monkeh@monkeh.net>
---
 src/atsam/i2c.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/atsam/i2c.c b/src/atsam/i2c.c
index 672eacef..fc56ce50 100644
--- a/src/atsam/i2c.c
+++ b/src/atsam/i2c.c
@@ -49,7 +49,7 @@ i2c_init(Twi *p_twi, uint32_t rate)
     p_twi->TWI_CR = TWI_CR_MSEN;
 
     uint32_t cldiv = 0, chdiv = 0, ckdiv = 0;
-    cldiv = SystemCoreClock / ((rate > 384000 ? 384000 : rate) * 4) - 4;
+    cldiv = SystemCoreClock / ((rate > 384000 ? 384000 : rate) * 2) - 4;
 
     while ((cldiv > 255) && (ckdiv < 7)) {
         ckdiv++;
@@ -57,7 +57,7 @@ i2c_init(Twi *p_twi, uint32_t rate)
     }
 
     if (rate > 348000) {
-        chdiv = SystemCoreClock / ((2 * rate - 384000) * 4) - 4;
+        chdiv = SystemCoreClock / ((2 * rate - 384000) * 2) - 4;
         while ((chdiv > 255) && (ckdiv < 7)) {
             ckdiv++;
             chdiv /= 2;