lib: utils: serial: Initial commit of xlnx-uartlite

Initial commit of the xlnx-uartlite device and FDT support. This was
tested by running OpenSBI on a modified QEMU virt machine using the
xlnx-uartlite for serial.

Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Xiang W <wxjstz@126.com>
Reviewed-by: Anup Patel <anup@brainfault.org>

lib/utils/fdt/fdt_helper.c

@@ -467,6 +467,24 @@ int fdt_parse_uart8250(void *fdt, struct platform_uart_data *uart,
 	return fdt_parse_uart8250_node(fdt, nodeoffset, uart);
 }
 
+int fdt_parse_xlnx_uartlite_node(void *fdt, int nodeoffset,
+			       struct platform_uart_data *uart)
+{
+	int rc;
+	uint64_t reg_addr, reg_size;
+
+	if (nodeoffset < 0 || !uart || !fdt)
+		return SBI_ENODEV;
+
+	rc = fdt_get_node_addr_size(fdt, nodeoffset, 0,
+				    &reg_addr, &reg_size);
+	if (rc < 0 || !reg_addr || !reg_size)
+		return SBI_ENODEV;
+	uart->addr = reg_addr;
+
+	return 0;
+}
+
 int fdt_parse_aplic_node(void *fdt, int nodeoff, struct aplic_data *aplic)
 {
 	bool child_found;

lib/utils/serial/fdt_serial.c

@@ -19,6 +19,7 @@ extern struct fdt_serial fdt_serial_litex;
 extern struct fdt_serial fdt_serial_htif;
 extern struct fdt_serial fdt_serial_shakti;
 extern struct fdt_serial fdt_serial_gaisler;
+extern struct fdt_serial fdt_serial_xlnx_uartlite;
 
 static struct fdt_serial *serial_drivers[] = {
 	&fdt_serial_uart8250,
@@ -26,7 +27,8 @@ static struct fdt_serial *serial_drivers[] = {
 	&fdt_serial_litex,
 	&fdt_serial_htif,
 	&fdt_serial_shakti,
-	&fdt_serial_gaisler
+	&fdt_serial_gaisler,
+	&fdt_serial_xlnx_uartlite,
 };
 
 static struct fdt_serial dummy = {

lib/utils/serial/fdt_serial_xlnx_uartlite.c

@@ -0,0 +1,35 @@
+/*
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2022 Western Digital Corporation or its affiliates.
+ *
+ * Authors:
+ *   Alistair Francis <alistair.francis@wdc.com>
+ */
+
+#include <sbi_utils/fdt/fdt_helper.h>
+#include <sbi_utils/serial/fdt_serial.h>
+#include <sbi_utils/serial/xlnx_uartlite.h>
+
+static int serial_xlnx_uartlite_init(void *fdt, int nodeoff,
+				const struct fdt_match *match)
+{
+	int rc;
+	struct platform_uart_data uart;
+
+	rc = fdt_parse_xlnx_uartlite_node(fdt, nodeoff, &uart);
+	if (rc)
+		return rc;
+
+	return xlnx_uartlite_init(uart.addr);
+}
+
+static const struct fdt_match serial_xlnx_uartlite_match[] = {
+	{ .compatible = "xlnx,xps-uartlite-1.00.a" },
+	{ },
+};
+
+struct fdt_serial fdt_serial_xlnx_uartlite = {
+	.match_table = serial_xlnx_uartlite_match,
+	.init = serial_xlnx_uartlite_init,
+};

lib/utils/serial/objects.mk

@@ -14,8 +14,10 @@ libsbiutils-objs-y += serial/fdt_serial_shakti.o
 libsbiutils-objs-y += serial/fdt_serial_sifive.o
 libsbiutils-objs-y += serial/fdt_serial_litex.o
 libsbiutils-objs-y += serial/fdt_serial_uart8250.o
+libsbiutils-objs-y += serial/fdt_serial_xlnx_uartlite.o
 libsbiutils-objs-y += serial/gaisler-uart.o
 libsbiutils-objs-y += serial/shakti-uart.o
 libsbiutils-objs-y += serial/sifive-uart.o
 libsbiutils-objs-y += serial/litex-uart.o
 libsbiutils-objs-y += serial/uart8250.o
+libsbiutils-objs-y += serial/xlnx-uartlite.o

lib/utils/serial/xlnx-uartlite.c

@@ -0,0 +1,67 @@
+/*
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2022 Western Digital Corporation or its affiliates.
+ *
+ * Authors:
+ *   Alistair Francis <alistair.francis@wdc.com>
+ */
+
+#include <sbi/riscv_io.h>
+#include <sbi/sbi_console.h>
+#include <sbi_utils/serial/xlnx_uartlite.h>
+
+/* clang-format off */
+
+#define UART_RX_OFFSET		0x00
+#define UART_TX_OFFSET		0x04
+#define UART_STATUS_OFFSET	0x08
+# define UART_STATUS_RXVALID	0x01
+# define UART_STATUS_RXFULL	0x02
+# define UART_STATUS_TXEMPTY	0x04
+# define UART_STATUS_TXFULL	0x08
+# define UART_STATUS_IE	0x10
+# define UART_STATUS_OVERRUN	0x20
+# define UART_STATUS_FRAME	0x40
+# define UART_STATUS_PARITY	0x80
+#define UART_CTRL_OFFSET	0x0C
+# define UART_CTRL_RST_TX	0x01
+# define UART_CTRL_RST_RX	0x02
+# define UART_CTRL_IE		0x10
+
+/* clang-format on */
+
+static volatile char *xlnx_uartlite_base;
+
+static void xlnx_uartlite_putc(char ch)
+{
+	while((readb(xlnx_uartlite_base + UART_STATUS_OFFSET) & UART_STATUS_TXFULL))
+		;
+
+	writeb(ch, xlnx_uartlite_base + UART_TX_OFFSET);
+}
+
+static int xlnx_uartlite_getc(void)
+{
+	u16 status = readb(xlnx_uartlite_base + UART_STATUS_OFFSET);
+
+	if (status & UART_STATUS_RXVALID)
+		return readb(xlnx_uartlite_base + UART_RX_OFFSET);
+
+	return -1;
+}
+
+static struct sbi_console_device xlnx_uartlite_console = {
+	.name = "xlnx-uartlite",
+	.console_putc = xlnx_uartlite_putc,
+	.console_getc = xlnx_uartlite_getc
+};
+
+int xlnx_uartlite_init(unsigned long base)
+{
+	xlnx_uartlite_base = (volatile char *)base;
+
+	sbi_console_set_device(&xlnx_uartlite_console);
+
+	return 0;
+}