lib: utils: Add simple FDT serial framework

We add simple serial framework which will select and use serial driver
based on details in FDT passed by previous booting stage.

Signed-off-by: Anup Patel <anup.patel@wdc.com>
Reviewed-by: Atish Patra <atish.patra@wdc.com>

include/sbi_utils/serial/fdt_serial.h

@@ -0,0 +1,28 @@
+/*
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2020 Western Digital Corporation or its affiliates.
+ *
+ * Authors:
+ *   Anup Patel <anup.patel@wdc.com>
+ */
+
+#ifndef __FDT_SERIAL_H__
+#define __FDT_SERIAL_H__
+
+#include <sbi/sbi_types.h>
+
+struct fdt_serial {
+	const struct fdt_match *match_table;
+	int (*init)(void *fdt, int nodeoff, const struct fdt_match *match);
+	void (*putc)(char ch);
+	int (*getc)(void);
+};
+
+void fdt_serial_putc(char ch);
+
+int fdt_serial_getc(void);
+
+int fdt_serial_init(void);
+
+#endif

lib/utils/serial/fdt_serial.c

@@ -0,0 +1,109 @@
+/*
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2020 Western Digital Corporation or its affiliates.
+ *
+ * Authors:
+ *   Anup Patel <anup.patel@wdc.com>
+ */
+
+#include <libfdt.h>
+#include <sbi/sbi_scratch.h>
+#include <sbi_utils/fdt/fdt_helper.h>
+#include <sbi_utils/serial/fdt_serial.h>
+
+extern struct fdt_serial fdt_serial_uart8250;
+extern struct fdt_serial fdt_serial_sifive;
+extern struct fdt_serial fdt_serial_htif;
+
+static struct fdt_serial *serial_drivers[] = {
+	&fdt_serial_uart8250,
+	&fdt_serial_sifive,
+	&fdt_serial_htif,
+};
+
+static void dummy_putc(char ch)
+{
+}
+
+static int dummy_getc(void)
+{
+	return -1;
+}
+
+static struct fdt_serial dummy = {
+	.match_table = NULL,
+	.init = NULL,
+	.putc = dummy_putc,
+	.getc = dummy_getc,
+};
+
+static struct fdt_serial *current_driver = &dummy;
+
+void fdt_serial_putc(char ch)
+{
+	current_driver->putc(ch);
+}
+
+int fdt_serial_getc(void)
+{
+	return current_driver->getc();
+}
+
+int fdt_serial_init(void)
+{
+	const void *prop;
+	struct fdt_serial *drv;
+	const struct fdt_match *match;
+	int pos, noff = -1, len, coff, rc;
+	void *fdt = sbi_scratch_thishart_arg1_ptr();
+
+	/* Find offset of node pointed by stdout-path */
+	coff = fdt_path_offset(fdt, "/chosen");
+	if (-1 < coff) {
+		prop = fdt_getprop(fdt, coff, "stdout-path", &len);
+		if (prop && len)
+			noff = fdt_path_offset(fdt, prop);
+	}
+
+	/* First check DT node pointed by stdout-path */
+	for (pos = 0; pos < array_size(serial_drivers) && -1 < noff; pos++) {
+		drv = serial_drivers[pos];
+
+		match = fdt_match_node(fdt, noff, drv->match_table);
+		if (!match)
+			continue;
+
+		if (drv->init) {
+			rc = drv->init(fdt, noff, match);
+			if (rc)
+				return rc;
+		}
+		current_driver = drv;
+		break;
+	}
+
+	/* Check if we found desired driver */
+	if (current_driver != &dummy)
+		goto done;
+
+	/* Lastly check all DT nodes */
+	for (pos = 0; pos < array_size(serial_drivers); pos++) {
+		drv = serial_drivers[pos];
+
+		noff = fdt_find_match(fdt, drv->match_table, &match);
+		if (noff < 0)
+			continue;
+
+		if (drv->init) {
+			rc = drv->init(fdt, noff, match);
+			if (rc)
+				return rc;
+		}
+		current_driver = drv;
+		break;
+	}
+
+done:
+	return 0;
+}

lib/utils/serial/fdt_serial_htif.c

@@ -0,0 +1,24 @@
+/*
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2020 Western Digital Corporation or its affiliates.
+ *
+ * Authors:
+ *   Anup Patel <anup.patel@wdc.com>
+ */
+
+#include <sbi_utils/fdt/fdt_helper.h>
+#include <sbi_utils/serial/fdt_serial.h>
+#include <sbi_utils/sys/htif.h>
+
+static const struct fdt_match serial_htif_match[] = {
+	{ .compatible = "ucb,htif0" },
+	{ },
+};
+
+struct fdt_serial fdt_serial_htif = {
+	.match_table = serial_htif_match,
+	.init = NULL,
+	.getc = htif_getc,
+	.putc = htif_putc
+};

lib/utils/serial/fdt_serial_sifive.c

@@ -0,0 +1,38 @@
+/*
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2020 Western Digital Corporation or its affiliates.
+ *
+ * Authors:
+ *   Anup Patel <anup.patel@wdc.com>
+ */
+
+#include <sbi_utils/fdt/fdt_helper.h>
+#include <sbi_utils/serial/fdt_serial.h>
+#include <sbi_utils/serial/sifive-uart.h>
+
+static int serial_sifive_init(void *fdt, int nodeoff,
+				const struct fdt_match *match)
+{
+	int rc;
+	struct platform_uart_data uart;
+
+	rc = fdt_parse_sifive_uart_node(fdt, nodeoff, &uart);
+	if (rc)
+		return rc;
+
+	return sifive_uart_init(uart.addr, uart.freq, uart.baud);
+}
+
+static const struct fdt_match serial_sifive_match[] = {
+	{ .compatible = "sifive,fu540-c000-uart" },
+	{ .compatible = "sifive,uart0" },
+	{ },
+};
+
+struct fdt_serial fdt_serial_sifive = {
+	.match_table = serial_sifive_match,
+	.init = serial_sifive_init,
+	.getc = sifive_uart_getc,
+	.putc = sifive_uart_putc
+};

lib/utils/serial/fdt_serial_uart8250.c

@@ -0,0 +1,39 @@
+/*
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2020 Western Digital Corporation or its affiliates.
+ *
+ * Authors:
+ *   Anup Patel <anup.patel@wdc.com>
+ */
+
+#include <sbi_utils/fdt/fdt_helper.h>
+#include <sbi_utils/serial/fdt_serial.h>
+#include <sbi_utils/serial/uart8250.h>
+
+static int serial_uart8250_init(void *fdt, int nodeoff,
+				const struct fdt_match *match)
+{
+	int rc;
+	struct platform_uart_data uart;
+
+	rc = fdt_parse_uart8250_node(fdt, nodeoff, &uart);
+	if (rc)
+		return rc;
+
+	return uart8250_init(uart.addr, uart.freq, uart.baud,
+			     uart.reg_shift, uart.reg_io_width);
+}
+
+static const struct fdt_match serial_uart8250_match[] = {
+	{ .compatible = "ns16550" },
+	{ .compatible = "ns16550a" },
+	{ },
+};
+
+struct fdt_serial fdt_serial_uart8250 = {
+	.match_table = serial_uart8250_match,
+	.init = serial_uart8250_init,
+	.getc = uart8250_getc,
+	.putc = uart8250_putc
+};

lib/utils/serial/objects.mk

@@ -7,5 +7,9 @@
 #   Anup Patel <anup.patel@wdc.com>
 #
 
+libsbiutils-objs-y += serial/fdt_serial.o
+libsbiutils-objs-y += serial/fdt_serial_htif.o
+libsbiutils-objs-y += serial/fdt_serial_sifive.o
+libsbiutils-objs-y += serial/fdt_serial_uart8250.o
 libsbiutils-objs-y += serial/sifive-uart.o
 libsbiutils-objs-y += serial/uart8250.o