lib: utils/serial: Add support for Altera JTAG UART

include/sbi_utils/serial/altr-juart.h

@@ -0,0 +1,17 @@
+/*
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2025 ISCAS
+ *
+ * Authors:
+ *   Icenowy Zheng <zhengxingda@iscas.ac.cn>
+ */
+
+#ifndef __SERIAL_ALTR_JUART_H__
+#define __SERIAL_ALTR_JUART_H__
+
+#include <sbi/sbi_types.h>
+
+int altr_juart_init(unsigned long base);
+
+#endif

lib/utils/serial/Kconfig

@@ -9,6 +9,11 @@ config FDT_SERIAL
 
 if FDT_SERIAL
 
+config FDT_SERIAL_ALTR_JUART
+	bool "Altera JTAG UART FDT driver"
+	select SERIAL_ALTR_JUART
+	default n
+
 config FDT_SERIAL_CADENCE
 	bool "Cadence UART FDT driver"
 	select SERIAL_CADENCE
@@ -56,6 +61,10 @@ config FDT_SERIAL_XILINX_UARTLITE
 
 endif
 
+config SERIAL_ALTR_JUART
+	bool "Altera JTAG UART support"
+	default n
+
 config SERIAL_CADENCE
 	bool "Cadence UART support"
 	default n

lib/utils/serial/altr-juart.c

@@ -0,0 +1,74 @@
+/*
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2025 ISCAS
+ *
+ * Authors:
+ *   Icenowy Zheng <zhengxingda@iscas.ac.cn>
+ */
+
+#include <sbi/riscv_io.h>
+#include <sbi/sbi_console.h>
+#include <sbi_utils/serial/altr-juart.h>
+
+/* clang-format off */
+
+#define JUART_DATA_OFFSET		0x00
+# define JUART_DATA_DATA_MASK		0x000000ff
+# define JUART_DATA_RVALID		(1 << 15)
+# define JUART_DATA_RAVAIL_MASK		0xffff0000
+# define JUART_DATA_RAVAIL_SHIFT	16
+#define JUART_CTRL_OFFSET		0x04
+# define JUART_CTRL_RE			(1 << 0)
+# define JUART_CTRL_WE			(1 << 1)
+# define JUART_CTRL_RI			(1 << 8)
+# define JUART_CTRL_WI			(1 << 9)
+# define JUART_CTRL_AC			(1 << 10)
+# define JUART_CTRL_WSPACE_MASK		0xffff0000
+# define JUART_CTRL_WSPACE_SHIFT	16
+
+/* clang-format on */
+
+static volatile char *altr_juart_base;
+
+static u32 get_reg(u32 offset)
+{
+	return readl(altr_juart_base + offset);
+}
+
+static void set_reg(u32 offset, u32 val)
+{
+	writel(val, altr_juart_base + offset);
+}
+
+static void altr_juart_putc(char ch)
+{
+	while(!(get_reg(JUART_CTRL_OFFSET) & JUART_CTRL_WSPACE_MASK))
+		;
+
+	set_reg(JUART_DATA_OFFSET, (unsigned char)ch);
+}
+
+static int altr_juart_getc(void)
+{
+	u32 reg = get_reg(JUART_DATA_OFFSET);
+	if (reg & JUART_DATA_RVALID)
+		return reg & JUART_DATA_DATA_MASK;
+
+	return -1;
+}
+
+static struct sbi_console_device altr_juart_console = {
+	.name = "altr-juart",
+	.console_putc = altr_juart_putc,
+	.console_getc = altr_juart_getc
+};
+
+int altr_juart_init(unsigned long base)
+{
+	altr_juart_base = (volatile char *)base;
+
+	sbi_console_set_device(&altr_juart_console);
+
+	return 0;
+}

lib/utils/serial/fdt_serial_altr_juart.c

@@ -0,0 +1,40 @@
+/*
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2025 ISCAS
+ *
+ * Authors:
+ *   Icenowy Zheng <zhengxingda@iscas.ac.cn>
+ */
+
+#include <sbi/sbi_error.h>
+#include <sbi_utils/fdt/fdt_helper.h>
+#include <sbi_utils/serial/fdt_serial.h>
+#include <sbi_utils/serial/altr-juart.h>
+
+static int serial_altr_juart_init(const void *fdt, int nodeoff,
+				  const struct fdt_match *match)
+{
+	uint64_t reg_addr, reg_size;
+	int rc;
+
+	if (nodeoff < 0 || !fdt)
+		return SBI_ENODEV;
+
+	rc = fdt_get_node_addr_size(fdt, nodeoff, 0, &reg_addr, &reg_size);
+	/* Two 32-bit registers */
+	if (rc < 0 || !reg_addr || !reg_size || reg_size < 0x8)
+		return SBI_ENODEV;
+
+	return altr_juart_init(reg_addr);
+}
+
+static const struct fdt_match serial_altr_juart_match[] = {
+	{ .compatible = "altr,juart-1.0" },
+	{ },
+};
+
+const struct fdt_driver fdt_serial_altr_juart = {
+	.match_table = serial_altr_juart_match,
+	.init = serial_altr_juart_init,
+};

lib/utils/serial/objects.mk

@@ -10,6 +10,9 @@
 libsbiutils-objs-$(CONFIG_FDT_SERIAL) += serial/fdt_serial.o
 libsbiutils-objs-$(CONFIG_FDT_SERIAL) += serial/fdt_serial_drivers.carray.o
 
+carray-fdt_serial_drivers-$(CONFIG_FDT_SERIAL_ALTR_JUART) += fdt_serial_altr_juart
+libsbiutils-objs-$(CONFIG_FDT_SERIAL_ALTR_JUART) += serial/fdt_serial_altr_juart.o
+
 carray-fdt_serial_drivers-$(CONFIG_FDT_SERIAL_CADENCE) += fdt_serial_cadence
 libsbiutils-objs-$(CONFIG_FDT_SERIAL_CADENCE) += serial/fdt_serial_cadence.o
 
@@ -37,6 +40,7 @@ libsbiutils-objs-$(CONFIG_FDT_SERIAL_UART8250) += serial/fdt_serial_uart8250.o
 carray-fdt_serial_drivers-$(CONFIG_FDT_SERIAL_XILINX_UARTLITE) += fdt_serial_xlnx_uartlite
 libsbiutils-objs-$(CONFIG_FDT_SERIAL_XILINX_UARTLITE) += serial/fdt_serial_xlnx_uartlite.o
 
+libsbiutils-objs-$(CONFIG_SERIAL_ALTR_JUART) += serial/altr-juart.o
 libsbiutils-objs-$(CONFIG_SERIAL_CADENCE) += serial/cadence-uart.o
 libsbiutils-objs-$(CONFIG_SERIAL_GAISLER) += serial/gaisler-uart.o
 libsbiutils-objs-$(CONFIG_SERIAL_RENESAS_SCIF) += serial/renesas_scif.o

platform/generic/configs/defconfig

@@ -49,6 +49,7 @@ CONFIG_FDT_RESET_SG2042_HWMON_MCU=y
 CONFIG_FDT_RESET_SUNXI_WDT=y
 CONFIG_FDT_RESET_SYSCON=y
 CONFIG_FDT_SERIAL=y
+CONFIG_FDT_SERIAL_ALTR_JUART=y
 CONFIG_FDT_SERIAL_CADENCE=y
 CONFIG_FDT_SERIAL_GAISLER=y
 CONFIG_FDT_SERIAL_HTIF=y