serial: Add serial driver for Intel MID
Add a specific serial driver for Intel MID platforms.
It has special fractional divider which can be programmed via UART_PS,
UART_MUL, and UART_DIV registers.
The UART clock is calculated as
UART clock = XTAL * UART_MUL / UART_DIV
The baudrate is calculated as
baud rate = UART clock / UART_PS / DLAB
Initialize fractional divider correctly for Intel Edison platform.
For backward compatibility we have to set initial DLAB value to 16
and speed to 115200 baud, where initial frequency is 29491200Hz, and
XTAL frequency is 38.4MHz.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>
diff --git a/drivers/serial/Kconfig b/drivers/serial/Kconfig
index 0900cc8..c0ec2ec 100644
--- a/drivers/serial/Kconfig
+++ b/drivers/serial/Kconfig
@@ -376,6 +376,15 @@
be used. It can be a constant or a function to get clock, eg,
get_serial_clock().
+config INTEL_MID_SERIAL
+ bool "Intel MID platform UART support"
+ depends on DM_SERIAL && OF_CONTROL
+ depends on INTEL_MID
+ select SYS_NS16550
+ help
+ Select this to enable a UART for Intel MID platforms.
+ This uses the ns16550 driver as a library.
+
config ROCKCHIP_SERIAL
bool "Rockchip on-chip UART support"
depends on DM_SERIAL && SPL_OF_PLATDATA