Maximilian Brune has uploaded this change for review.
drivers/uart/sifive.c: Fix divisor calculation
The divisor is calculated using the following formula:
div = (frequency / baudrate) - 1;
The current implementation however essentially cacluates:
div = (frequency / baudrate);
Signed-off-by: Maximilian Brune <maximilian.brune@9elements.com>
Change-Id: I8a0898ce9016a70c0f91dc8a99fc1cf9e46d20c4
---
M src/drivers/uart/sifive.c
1 file changed, 8 insertions(+), 3 deletions(-)
git pull ssh://review.coreboot.org:29418/coreboot refs/changes/51/79951/1
diff --git a/src/drivers/uart/sifive.c b/src/drivers/uart/sifive.c
index d1b89dc..68759c8 100644
--- a/src/drivers/uart/sifive.c
+++ b/src/drivers/uart/sifive.c
@@ -47,9 +47,14 @@
void uart_init(unsigned int idx)
{
- unsigned int div;
- div = uart_baudrate_divisor(get_uart_baudrate(),
- uart_platform_refclk(), uart_input_clock_divider());
+ // according to FU740 manual:
+ // f_baud = f_in / (div + 1)
+ // <=>
+ // div = (f_in / f_baud) - 1
+ unsigned int div = uart_baudrate_divisor(get_uart_baudrate(), uart_platform_refclk(),
+ uart_input_clock_divider());
+ div -= 1;
+
sifive_uart_init(uart_platform_baseptr(idx), div);
}
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