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author | Kyösti Mälkki <kyosti.malkki@gmail.com> | 2014-02-17 19:37:52 +0200 |
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committer | Kyösti Mälkki <kyosti.malkki@gmail.com> | 2014-03-04 15:22:08 +0100 |
commit | 3ee1668ab4fbf75b256ac8eef4273b1ea445c998 (patch) | |
tree | 59f35a43b85c5da6a0d9d38aba7f391971cbc980 /src/lib/uart8250mem.c | |
parent | c76b3d6cca4a6135e5a7d7f3c2d9aa5128ef23f0 (diff) |
uart8250: Fix and unify baudrate divisor calculation
Divisor is a function of requested baudrate, platform-specific
reference clock and amount of oversampling done on the UART reference.
Calculate this parameter with divisor rounded to nearest integer.
When building without option_table or when there is no entry for
baud_rate, CONFIG_TTYS0_BAUD is used for default baudrate.
For OxPCIe use of 4 MHz for reference was arbitrary giving correct
divisor for 115200 but somewhat inaccurate for lower baudrates.
Actual hardware is 62500000 with 16 times oversampling.
FIXME: Field for baudrate in lb_tables is still incorrect.
Change-Id: I68539738469af780fadd3392263dd9b3d5964d2d
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: http://review.coreboot.org/5229
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
Diffstat (limited to 'src/lib/uart8250mem.c')
-rw-r--r-- | src/lib/uart8250mem.c | 24 |
1 files changed, 1 insertions, 23 deletions
diff --git a/src/lib/uart8250mem.c b/src/lib/uart8250mem.c index 040e732df3..5e96825834 100644 --- a/src/lib/uart8250mem.c +++ b/src/lib/uart8250mem.c @@ -21,10 +21,6 @@ #include <arch/io.h> #include <uart.h> #include <uart8250.h> -#include <pc80/mc146818rtc.h> -#if CONFIG_USE_OPTION_TABLE -#include "option_table.h" -#endif #include <device/device.h> #include <delay.h> @@ -96,7 +92,6 @@ void uart8250_mem_init(unsigned base_port, unsigned divisor) /* DLAB on */ write8(base_port + UART_LCR, UART_LCR_DLAB | CONFIG_TTYS0_LCS); - /* Set Baud Rate Divisor. 12 ==> 9600 Baud */ write8(base_port + UART_DLL, divisor & 0xFF); write8(base_port + UART_DLM, (divisor >> 8) & 0xFF); @@ -106,27 +101,11 @@ void uart8250_mem_init(unsigned base_port, unsigned divisor) u32 uart_mem_init(void) { - unsigned uart_baud = CONFIG_TTYS0_BAUD; u32 uart_bar = 0; unsigned div; - /* find out the correct baud rate */ -#if !defined(__SMM__) && CONFIG_USE_OPTION_TABLE - static const unsigned baud[8] = { 115200, 57600, 38400, 19200, 9600, 4800, 2400, 1200 }; - unsigned b_index = 0; -#if defined(__PRE_RAM__) - b_index = read_option(baud_rate, 0); - b_index &= 7; - uart_baud = baud[b_index]; -#else - if (get_option(&b_index, "baud_rate") == CB_SUCCESS) - uart_baud = baud[b_index]; -#endif -#endif - /* Now find the UART base address and calculate the divisor */ #if CONFIG_DRIVERS_OXFORD_OXPCIE - #if defined(MORE_TESTING) && !defined(__SIMPLE_DEVICE__) device_t dev = dev_find_device(0x1415, 0xc158, NULL); if (!dev) @@ -145,10 +124,9 @@ u32 uart_mem_init(void) #endif uart_bar = CONFIG_OXFORD_OXPCIE_BASE_ADDRESS + 0x1000; // 1st UART // uart_bar = CONFIG_OXFORD_OXPCIE_BASE_ADDRESS + 0x2000; // 2nd UART - - div = 4000000 / uart_baud; #endif + div = uart_baudrate_divisor(default_baudrate(), uart_platform_refclk(), 16); if (uart_bar) uart8250_mem_init(uart_bar, div); |