[PATCH v1 2/4] board: nuvoton: update console environment variable

[Jim Liu]

If CONFIG_SYS_SKIP_UART_INIT is enabled, calculate the
current baud rate and update the "console" environment
variable.

Signed-off-by: Jim Liu <JJLIU0 at nuvoton.com>
---
 board/nuvoton/arbel_evb/Kconfig |  1 +
 board/nuvoton/common/Kconfig    |  9 +++++
 board/nuvoton/common/Makefile   |  1 +
 board/nuvoton/common/common.c   | 71 +++++++++++++++++++++++++++++++++
 board/nuvoton/common/common.h   | 11 +++++
 board/nuvoton/poleg_evb/Kconfig |  1 +
 6 files changed, 94 insertions(+)
 create mode 100644 board/nuvoton/common/Kconfig
 create mode 100644 board/nuvoton/common/Makefile
 create mode 100644 board/nuvoton/common/common.c
 create mode 100644 board/nuvoton/common/common.h

diff --git a/board/nuvoton/arbel_evb/Kconfig b/board/nuvoton/arbel_evb/Kconfig
index 33c589f1fb..ed1c1ad8ee 100644
--- a/board/nuvoton/arbel_evb/Kconfig
+++ b/board/nuvoton/arbel_evb/Kconfig
@@ -15,4 +15,5 @@ config SYS_MEM_TOP_HIDE
 	help
 	  Reserve memory for ECC/GFX/OPTEE/TIP/CP.
 
+source "board/nuvoton/common/Kconfig"
 endif
diff --git a/board/nuvoton/common/Kconfig b/board/nuvoton/common/Kconfig
new file mode 100644
index 0000000000..61de7bc5f8
--- /dev/null
+++ b/board/nuvoton/common/Kconfig
@@ -0,0 +1,9 @@
+if ARCH_NPCM
+
+config SYS_SKIP_UART_INIT
+	bool "Skip UART initialization"
+	depends on NPCM_SERIAL
+	help
+	  Select this if the UART you want to use is already
+	  initialized by the time U-Boot starts its execution.
+endif
diff --git a/board/nuvoton/common/Makefile b/board/nuvoton/common/Makefile
new file mode 100644
index 0000000000..52e77185c4
--- /dev/null
+++ b/board/nuvoton/common/Makefile
@@ -0,0 +1 @@
+obj-y	+= common.o
diff --git a/board/nuvoton/common/common.c b/board/nuvoton/common/common.c
new file mode 100644
index 0000000000..6da9d93e80
--- /dev/null
+++ b/board/nuvoton/common/common.c
@@ -0,0 +1,71 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (c) 2023 Nuvoton Technology Corp.
+ */
+
+#include <common.h>
+#include <clk.h>
+#include <dm.h>
+#include <env.h>
+#include <serial.h>
+#include <linux/delay.h>
+
+#define UART_DLL	0x0
+#define UART_DLM	0x4
+#define UART_LCR	0xc
+#define LCR_DLAB	BIT(7)
+
+int board_set_console(void)
+{
+	const unsigned long baudrate_table[] = CFG_SYS_BAUDRATE_TABLE;
+	struct udevice *dev = gd->cur_serial_dev;
+	unsigned int baudrate, max_delta;
+	void __iomem *uart_reg;
+	struct clk clk;
+	char string[32];
+	u32 uart_clk;
+	u8 dll, dlm;
+	u16 divisor;
+	int ret, i;
+
+	/* If uart init is skipped, update the actual baudrate in boot arguments */
+	if (!IS_ENABLED(CONFIG_SYS_SKIP_UART_INIT))
+		return 0;
+	if (!dev)
+		return 0;
+	uart_reg = dev_read_addr_ptr(dev);
+	ret = clk_get_by_index(dev, 0, &clk);
+	if (ret)
+		return 0;
+	uart_clk = clk_get_rate(&clk);
+	setbits_8(uart_reg + UART_LCR, LCR_DLAB);
+	dll = readb(uart_reg + UART_DLL);
+	dlm = readb(uart_reg + UART_DLM);
+	clrbits_8(uart_reg + UART_LCR, LCR_DLAB);
+	divisor = dll | (dlm << 8);
+	baudrate =  uart_clk / ((16 * (divisor + 2)));
+	for (i = 0; i < ARRAY_SIZE(baudrate_table); ++i) {
+		max_delta = baudrate_table[i] / 20;
+		if (abs(baudrate - baudrate_table[i]) < max_delta) {
+			/* The baudrate is supported */
+			gd->baudrate = baudrate_table[i];
+			break;
+		}
+	}
+	if (i == ARRAY_SIZE(baudrate_table)) {
+		/* current baudrate is not suitable, set to default */
+		divisor = DIV_ROUND_CLOSEST(uart_clk, 16 * gd->baudrate) - 2;
+		setbits_8(uart_reg + UART_LCR, LCR_DLAB);
+		writeb(divisor & 0xff, uart_reg + UART_DLL);
+		writeb(divisor >> 8, uart_reg + UART_DLM);
+		clrbits_8(uart_reg + UART_LCR, LCR_DLAB);
+		udelay(100);
+		printf("\r\nUART(source %u): change baudrate from %u to %u\n",
+		       uart_clk, baudrate, uart_clk / ((16 * (divisor + 2))));
+	}
+	debug("Set env baudrate=%u\n", gd->baudrate);
+	snprintf(string, sizeof(string), "ttyS0,%un8", gd->baudrate);
+	env_set("console", string);
+
+	return 0;
+}
diff --git a/board/nuvoton/common/common.h b/board/nuvoton/common/common.h
new file mode 100644
index 0000000000..64a09670cb
--- /dev/null
+++ b/board/nuvoton/common/common.h
@@ -0,0 +1,11 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Copyright (c) 2023 Nuvoton Technology Corp.
+ */
+
+#ifndef _NUVOTON_COMMON_H
+#define _NUVOTON_COMMON_H
+
+int board_set_console(void);
+
+#endif /* _NUVOTON_COMMON_H */
diff --git a/board/nuvoton/poleg_evb/Kconfig b/board/nuvoton/poleg_evb/Kconfig
index d3f4c1dd81..6f7f1ef157 100644
--- a/board/nuvoton/poleg_evb/Kconfig
+++ b/board/nuvoton/poleg_evb/Kconfig
@@ -22,4 +22,5 @@ config TARGET_POLEG_EVB
 
 endchoice
 
+source "board/nuvoton/common/Kconfig"
 endif
-- 
2.25.1