drivers/uart: Use uart_platform_refclk for all UART models

Allow the platform to override the input clock for the UART by
implementing the routine uart_platform_refclk and setting the Kconfig
value UART_OVERRIDE_REFCLK.  Provide a default uart_platform_refclk
routine which is disabled when UART_OVERRIDE_REFCLK is selected.  This
works around ROMCC not supporting weak routines.

Testing on Galileo:
*  Edit the src/mainboard/intel/galileo/Makefile.inc file:
   *  Add "select ADD_FSP_PDAT_FILE"
   *  Add "select ADD_FSP_RAW_BIN"
   *  Add "select ADD_RMU_FILE"
*  Place the FSP.bin file in the location specified by CONFIG_FSP_FILE
*  Place the pdat.bin files in the location specified by
   CONFIG_FSP_PDAT_FILE
*  Place the rmu.bin file in the location specified by CONFIG_RMU_FILE
*  Build EDK2 CorebootPayloadPkg/CorebootPayloadPkgIa32.dsc to generate
   UEFIPAYLOAD.fd
*  Testing is successful when CorebootPayloadPkg is able to properly
   initialize the serial port without using built-in values.

Change-Id: If4afc45a828e5ba935fecb6d95b239625e912d14
Signed-off-by: Lee Leahy <leroy.p.leahy@intel.com>
Reviewed-on: https://review.coreboot.org/14612
Tested-by: build bot (Jenkins)
Reviewed-by: Martin Roth <martinroth@google.com>

17 files changed, 38 insertions, 44 deletions

diff --git a/src/cpu/allwinner/a10/Kconfig b/src/cpu/allwinner/a10/Kconfig
index 814b69e1f02c..0e5aba98b70e 100644
--- a/src/cpu/allwinner/a10/Kconfig
+++ b/src/cpu/allwinner/a10/Kconfig
@@ -13,5 +13,6 @@ config CPU_SPECIFIC_OPTIONS
 	select HAVE_MONOTONIC_TIMER
 	select HAVE_UART_SPECIAL
 	select BOOTBLOCK_CONSOLE
+	select UART_OVERRIDE_REFCLK
 
 endif # if CPU_ALLWINNER_A10
diff --git a/src/cpu/ti/am335x/Kconfig b/src/cpu/ti/am335x/Kconfig
index 8d3c691161d5..f44c69d6867d 100644
--- a/src/cpu/ti/am335x/Kconfig
+++ b/src/cpu/ti/am335x/Kconfig
@@ -7,5 +7,6 @@ config CPU_TI_AM335X
 	select HAVE_UART_SPECIAL
 	select BOOTBLOCK_CONSOLE
 	select GENERIC_UDELAY
+	select UART_OVERRIDE_REFCLK
 	bool
 	default n
diff --git a/src/drivers/uart/Kconfig b/src/drivers/uart/Kconfig
index cb129b064307..4faa48d9f0ba 100644
--- a/src/drivers/uart/Kconfig
+++ b/src/drivers/uart/Kconfig
@@ -20,6 +20,13 @@ config UART_OVERRIDE_INPUT_CLOCK_DIVIDER
 	  Set to "y" when the platform overrides the uart_input_clock_divider
 	  routine.
 
+config UART_OVERRIDE_REFCLK
+	boolean
+	default n
+	help
+	  Set to "y" when the platform overrides the uart_platform_refclk
+	  routine.
+
 config DRIVERS_UART_8250MEM
 	bool
 	default n
@@ -39,6 +46,7 @@ config DRIVERS_UART_OXPCIE
 	depends on PCI
 	select DRIVERS_UART_8250MEM
 	select EARLY_PCI_BRIDGE
+	select UART_OVERRIDE_REFCLK
 	help
 	  Support for Oxford OXPCIe952 serial port PCIe cards.
 	  Currently only devices with the vendor ID 0x1415 and device ID
diff --git a/src/drivers/uart/oxpcie_early.c b/src/drivers/uart/oxpcie_early.c
index 6582a9e5abd4..0a778d98c7fd 100644
--- a/src/drivers/uart/oxpcie_early.c
+++ b/src/drivers/uart/oxpcie_early.c
@@ -92,10 +92,7 @@ void uart_fill_lb(void *data)
 	serial.baseaddr = uart_platform_base(CONFIG_UART_FOR_CONSOLE);
 	serial.baud = default_baudrate();
 	serial.regwidth = 1;
-	if (IS_ENABLED(CONFIG_UART_USE_REFCLK_AS_INPUT_CLOCK))
-		serial.input_hertz = uart_platform_refclk();
-	else
-		serial.input_hertz = 0;
+	serial.input_hertz = uart_platform_refclk();
 	serial.uart_pci_addr = CONFIG_UART_PCI_ADDR;
 	lb_add_serial(&serial, data);
 
diff --git a/src/drivers/uart/pl011.c b/src/drivers/uart/pl011.c
index 808cb465387d..0c7ac08ed554 100644
--- a/src/drivers/uart/pl011.c
+++ b/src/drivers/uart/pl011.c
@@ -48,10 +48,7 @@ void uart_fill_lb(void *data)
 	serial.baseaddr = uart_platform_base(CONFIG_UART_FOR_CONSOLE);
 	serial.baud = default_baudrate();
 	serial.regwidth = 1;
-	if (IS_ENABLED(CONFIG_UART_USE_REFCLK_AS_INPUT_CLOCK))
-		serial.input_hertz = uart_platform_refclk();
-	else
-		serial.input_hertz = 0;
+	serial.input_hertz = uart_platform_refclk();
 	serial.uart_pci_addr = CONFIG_UART_PCI_ADDR;
 	lb_add_serial(&serial, data);
 
diff --git a/src/drivers/uart/uart8250io.c b/src/drivers/uart/uart8250io.c
index 69244f58dfb9..89c447658a51 100644
--- a/src/drivers/uart/uart8250io.c
+++ b/src/drivers/uart/uart8250io.c
@@ -27,16 +27,6 @@
 
 /* Should support 8250, 16450, 16550, 16550A type UARTs */
 
-/* Nominal values only, good for the range of choices Kconfig offers for
- * set of standard baudrates.
- */
-
-/* Multiply the maximim baud-rate by the default oversample rate to compute
- * the default input clock to the UART.  The uart_baudrate_divisor divides
- * by the oversample clock to determine the final baud-rate.
- */
-#define BAUDRATE_REFCLK		(115200 * 16)
-
 /* Expected character delay at 1200bps is 9ms for a working UART
  * and no flow-control. Assume UART as stuck if shift register
  * or FIFO takes more than 50ms per character to appear empty.
@@ -115,7 +105,7 @@ uintptr_t uart_platform_base(int idx)
 void uart_init(int idx)
 {
 	unsigned int div;
-	div = uart_baudrate_divisor(default_baudrate(), BAUDRATE_REFCLK,
+	div = uart_baudrate_divisor(default_baudrate(), uart_platform_refclk(),
 		uart_input_clock_divider());
 	uart8250_init(uart_platform_base(idx), div);
 }
@@ -143,10 +133,7 @@ void uart_fill_lb(void *data)
 	serial.baseaddr = uart_platform_base(CONFIG_UART_FOR_CONSOLE);
 	serial.baud = default_baudrate();
 	serial.regwidth = 1;
-	if (IS_ENABLED(CONFIG_UART_USE_REFCLK_AS_INPUT_CLOCK))
-		serial.input_hertz = uart_platform_refclk();
-	else
-		serial.input_hertz = 0;
+	serial.input_hertz = uart_platform_refclk();
 	serial.uart_pci_addr = CONFIG_UART_PCI_ADDR;
 	lb_add_serial(&serial, data);
 
diff --git a/src/drivers/uart/uart8250mem.c b/src/drivers/uart/uart8250mem.c
index 4b87756d0bbd..cf58423b869d 100644
--- a/src/drivers/uart/uart8250mem.c
+++ b/src/drivers/uart/uart8250mem.c
@@ -157,10 +157,7 @@ void uart_fill_lb(void *data)
 		serial.regwidth = sizeof(uint32_t);
 	else
 		serial.regwidth = sizeof(uint8_t);
-	if (IS_ENABLED(CONFIG_UART_USE_REFCLK_AS_INPUT_CLOCK))
-		serial.input_hertz = uart_platform_refclk();
-	else
-		serial.input_hertz = 0;
+	serial.input_hertz = uart_platform_refclk();
 	serial.uart_pci_addr = CONFIG_UART_PCI_ADDR;
 	lb_add_serial(&serial, data);
 
diff --git a/src/drivers/uart/util.c b/src/drivers/uart/util.c
index 5e8d2232521b..86da8dc74614 100644
--- a/src/drivers/uart/util.c
+++ b/src/drivers/uart/util.c
@@ -59,3 +59,19 @@ unsigned int uart_input_clock_divider(void)
 	return 16;
 }
 #endif
+
+#if !IS_ENABLED(CONFIG_UART_OVERRIDE_REFCLK)
+unsigned int uart_platform_refclk(void)
+{
+	/* Specify the default input clock frequency for the UART.
+	 *
+	 * The older UART's used an input clock frequency of 1.8432 MHz which
+	 * with the 16x oversampling provided the maximum baud-rate of 115200.
+	 * Specify this as maximum baud-rate multiplied by oversample so that
+	 * it is obvious that the maximum baud rate is 115200 when divided by
+	 * oversample clock.  Also note that crystal on the board does not
+	 * change when software selects another input clock divider.
+	 */
+	return 115200 * 16;
+}
+#endif
diff --git a/src/soc/imgtec/pistachio/Kconfig b/src/soc/imgtec/pistachio/Kconfig
index 5ea6b95107c0..da33cc5c96a8 100644
--- a/src/soc/imgtec/pistachio/Kconfig
+++ b/src/soc/imgtec/pistachio/Kconfig
@@ -25,6 +25,7 @@ config CPU_IMGTEC_PISTACHIO
 	select SPI_ATOMIC_SEQUENCING
 	select GENERIC_GPIO_LIB
 	select HAVE_HARD_RESET
+	select UART_OVERRIDE_REFCLK
 	bool
 
 if CPU_IMGTEC_PISTACHIO
diff --git a/src/soc/intel/apollolake/uart_early.c b/src/soc/intel/apollolake/uart_early.c
index e8dfeda565d0..0e530609bdf3 100644
--- a/src/soc/intel/apollolake/uart_early.c
+++ b/src/soc/intel/apollolake/uart_early.c
@@ -68,12 +68,6 @@ uintptr_t uart_platform_base(int idx)
 	return (CONFIG_CONSOLE_UART_BASE_ADDRESS);
 }
 
-unsigned int uart_platform_refclk(void)
-{
-	/* That's within 0.5% of the actual value we've set earlier */
-	return 115200 * 16;
-}
-
 static const struct pad_config uart_gpios[] = {
 	PAD_CFG_NF(GPIO_42, NATIVE, DEEP, NF1),		/* UART1 RX */
 	PAD_CFG_NF(GPIO_43, NATIVE, DEEP, NF1),		/* UART1 TX */
diff --git a/src/soc/intel/quark/Kconfig b/src/soc/intel/quark/Kconfig
index ae25c328c6b7..6a2349fb8db7 100644
--- a/src/soc/intel/quark/Kconfig
+++ b/src/soc/intel/quark/Kconfig
@@ -30,6 +30,7 @@ config CPU_SPECIFIC_OPTIONS
 	select SOC_INTEL_COMMON
 	select SOC_SETS_MTRRS
 	select TSC_CONSTANT_RATE
+	select UART_OVERRIDE_REFCLK
 	select UDELAY_TSC
 	select UNCOMPRESSED_RAMSTAGE
 	select USE_MARCH_586
diff --git a/src/soc/intel/skylake/uart_debug.c b/src/soc/intel/skylake/uart_debug.c
index c463bea14546..f3d576b3aa70 100644
--- a/src/soc/intel/skylake/uart_debug.c
+++ b/src/soc/intel/skylake/uart_debug.c
@@ -18,17 +18,6 @@
 #include <soc/iomap.h>
 #include <soc/serialio.h>
 
-unsigned int uart_platform_refclk(void)
-{
-	/*
-	 * Set M and N divisor inputs and enable clock.
-	 * Main reference frequency to UART is:
-	 *  120MHz * M / N = 120MHz * 48 / 3125 = 1843200Hz
-	 * The different order below is to handle integer math overflow.
-	 */
-	return 120 * MHz / SIO_REG_PPR_CLOCK_N_DIV * SIO_REG_PPR_CLOCK_M_DIV;
-}
-
 uintptr_t uart_platform_base(int idx)
 {
 	/* Same base address for all debug port usage. In reality UART2
diff --git a/src/soc/marvell/armada38x/Kconfig b/src/soc/marvell/armada38x/Kconfig
index 6754a0f1f6b8..ed8cbe810046 100644
--- a/src/soc/marvell/armada38x/Kconfig
+++ b/src/soc/marvell/armada38x/Kconfig
@@ -10,6 +10,7 @@ config SOC_MARVELL_ARMADA38X
 	select RETURN_FROM_VERSTAGE
 	select BOOTBLOCK_CUSTOM
 	select GENERIC_UDELAY
+	select UART_OVERRIDE_REFCLK
 
 if SOC_MARVELL_ARMADA38X
 
diff --git a/src/soc/nvidia/tegra132/Kconfig b/src/soc/nvidia/tegra132/Kconfig
index 502e7c4c72c3..08ed47567beb 100644
--- a/src/soc/nvidia/tegra132/Kconfig
+++ b/src/soc/nvidia/tegra132/Kconfig
@@ -13,6 +13,7 @@ config SOC_NVIDIA_TEGRA132
 	select HAVE_HARD_RESET
 	select HAVE_UART_SPECIAL
 	select GENERIC_GPIO_LIB
+	select UART_OVERRIDE_REFCLK
 
 if SOC_NVIDIA_TEGRA132
 
diff --git a/src/soc/rockchip/rk3288/Kconfig b/src/soc/rockchip/rk3288/Kconfig
index 8b15d3dc457c..0f394b18b43d 100644
--- a/src/soc/rockchip/rk3288/Kconfig
+++ b/src/soc/rockchip/rk3288/Kconfig
@@ -27,6 +27,7 @@ config SOC_ROCKCHIP_RK3288
 	select UNCOMPRESSED_RAMSTAGE
 	select GENERIC_GPIO_LIB
 	select RTC
+	select UART_OVERRIDE_REFCLK
 
 if SOC_ROCKCHIP_RK3288
 
diff --git a/src/soc/rockchip/rk3399/Kconfig b/src/soc/rockchip/rk3399/Kconfig
index 43bb03bd4e4c..38d0f0041342 100644
--- a/src/soc/rockchip/rk3399/Kconfig
+++ b/src/soc/rockchip/rk3399/Kconfig
@@ -12,6 +12,7 @@ config SOC_ROCKCHIP_RK3399
 	select GENERIC_UDELAY
 	select HAVE_MONOTONIC_TIMER
 	select UNCOMPRESSED_RAMSTAGE
+	select UART_OVERRIDE_REFCLK
 
 if SOC_ROCKCHIP_RK3399
 
diff --git a/src/southbridge/amd/pi/hudson/Kconfig b/src/southbridge/amd/pi/hudson/Kconfig
index aa55339ea0b8..8fe3b2d897a5 100644
--- a/src/southbridge/amd/pi/hudson/Kconfig
+++ b/src/southbridge/amd/pi/hudson/Kconfig
@@ -235,6 +235,7 @@ config HUDSON_UART
 	select DRIVERS_UART_8250MEM
 	select DRIVERS_UART_8250MEM_32
 	select NO_UART_ON_SUPERIO
+	select UART_OVERRIDE_REFCLK
 	help
 	  There are two UART controllers in Kern.
 	  The UART registers are memory-mapped. UART