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authorStefan Roese <sr@denx.de>2015-03-18 09:30:54 +0100
committerHeiko Schocher <hs@denx.de>2015-03-18 09:48:42 +0100
commitf582a1583b2c7ae91737f3b1a0b850e7f4ef68bb (patch)
tree1301c2bbd5c9f0a2f1bdadfdfdd31c0b0c1b5314 /drivers/i2c
parente6fbc3e4f1f2f974ec8efe9d52cfcb22b87f6294 (diff)
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i2c: mvtwsi: Fix problem with baud rate calculation
The current implementation for baudrate calculation is incorrect. This part from the formula: "2 ^ (n + 1)" is not equivalent to (1 << n) but to (2 << n)! This patch fixes this and moves this calculation to a function instead of using a macro. This new function is taken from the Linux kernel. This was detected and tested on the Marvell Armada A38x DB-88F6820-GP eval board. Signed-off-by: Stefan Roese <sr@denx.de> Cc: Prafulla Wadaskar <prafulla@marvell.com> Cc: Luka Perkov <luka.perkov@sartura.hr> Cc: Hans de Goede <hdegoede@redhat.com> Cc: Ian Campbell <ijc@hellion.org.uk> Cc: Heiko Schocher <hs@denx.de> Acked-by: Hans de Goede <hdegoede@redhat.com>
Diffstat (limited to 'drivers/i2c')
-rw-r--r--drivers/i2c/mvtwsi.c17
1 files changed, 9 insertions, 8 deletions
diff --git a/drivers/i2c/mvtwsi.c b/drivers/i2c/mvtwsi.c
index 9b2ca1e..6f6edd5 100644
--- a/drivers/i2c/mvtwsi.c
+++ b/drivers/i2c/mvtwsi.c
@@ -228,13 +228,14 @@ static int twsi_stop(int status)
return status;
}
-/*
- * Ugly formula to convert m and n values to a frequency comes from
- * TWSI specifications
- */
-
-#define TWSI_FREQUENCY(m, n) \
- (CONFIG_SYS_TCLK / (10 * (m + 1) * (1 << n)))
+static unsigned int twsi_calc_freq(const int n, const int m)
+{
+#ifdef CONFIG_SUNXI
+ return CONFIG_SYS_TCLK / (10 * (m + 1) * (1 << n));
+#else
+ return CONFIG_SYS_TCLK / (10 * (m + 1) * (2 << n));
+#endif
+}
/*
* Reset controller.
@@ -266,7 +267,7 @@ static unsigned int twsi_i2c_set_bus_speed(struct i2c_adapter *adap,
/* compute m, n setting for highest speed not above requested speed */
for (n = 0; n < 8; n++) {
for (m = 0; m < 16; m++) {
- tmp_speed = TWSI_FREQUENCY(m, n);
+ tmp_speed = twsi_calc_freq(n, m);
if ((tmp_speed <= requested_speed)
&& (tmp_speed > highest_speed)) {
highest_speed = tmp_speed;