[coreboot-gerrit] New patch to review for coreboot: mb/lowrisc/nexys4ddr: Actually fix the UART clock setup
Jonathan Neuschäfer (j.neuschaefer@gmx.net)
gerrit at coreboot.org
Sat Oct 29 22:39:35 CEST 2016
Jonathan Neuschäfer (j.neuschaefer at gmx.net) just uploaded a new patch set to gerrit, which you can find at https://review.coreboot.org/17188
-gerrit
commit 12cf0cdcfbd140db191009f665c10127a4bae687
Author: Jonathan Neuschäfer <j.neuschaefer at gmx.net>
Date: Sat Oct 29 21:48:18 2016 +0200
mb/lowrisc/nexys4ddr: Actually fix the UART clock setup
Ron's code calculated the DLL and DLM registers of the 8250 UART, but
that's the job of the UART driver. uart_input_clock_divider isn't needed
anymore because the default value of 16 works.
As a bonus, the baud rate can now be selected in Kconfig, instead of
being hardcoded at 115200.
TEST=Booted the board at 9600 and 115200 baud.
Change-Id: I3d5e49568b798a6a6d944db1161def7d0a2d3b48
Signed-off-by: Jonathan Neuschäfer <j.neuschaefer at gmx.net>
---
src/mainboard/lowrisc/nexys4ddr/Kconfig | 1 -
src/mainboard/lowrisc/nexys4ddr/uart.c | 13 ++-----------
2 files changed, 2 insertions(+), 12 deletions(-)
diff --git a/src/mainboard/lowrisc/nexys4ddr/Kconfig b/src/mainboard/lowrisc/nexys4ddr/Kconfig
index f0a3637..5a6bfb2 100644
--- a/src/mainboard/lowrisc/nexys4ddr/Kconfig
+++ b/src/mainboard/lowrisc/nexys4ddr/Kconfig
@@ -21,7 +21,6 @@ config BOARD_SPECIFIC_OPTIONS # dummy
select DRIVERS_UART_8250MEM
select BOOT_DEVICE_NOT_SPI_FLASH
select UART_OVERRIDE_REFCLK
- select UART_OVERRIDE_INPUT_CLOCK_DIVIDER
config MAINBOARD_DIR
string
diff --git a/src/mainboard/lowrisc/nexys4ddr/uart.c b/src/mainboard/lowrisc/nexys4ddr/uart.c
index e3c233f80..d19ce52 100644
--- a/src/mainboard/lowrisc/nexys4ddr/uart.c
+++ b/src/mainboard/lowrisc/nexys4ddr/uart.c
@@ -24,17 +24,8 @@ uintptr_t uart_platform_base(int idx)
return (uintptr_t) 0x42000000;
}
-/* these are currently not quite right but they are here for reference
- * and will be fixed when lowrisc gives us a standard clock
- * and set of values. */
-// divisor = clk_freq / (16 * Baud)
-unsigned int uart_input_clock_divider(void)
-{
- return (25 * 1000 * 1000u / (16u * 115200u)) % 0x100;
-}
-
-// System clock 25 MHz, 115200 baud rate
+/* The clock which the UART is based on */
unsigned int uart_platform_refclk(void)
{
- return (25 * 1000 * 1000u / (16u * 115200u)) >> 8;
+ return 25 * MHz;
}
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