1 files changed, 56 insertions, 0 deletions
diff --git a/drivers/serial/pl011.c b/drivers/serial/pl011.c
new file mode 100644
index 0000000..d11aa00
--- /dev/null
+++ b/drivers/serial/pl011.c
@@ -0,0 +1,56 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * pl011.c - ARM PrimeCell PL011 serial, polled io
+ *
+ * the register layout is shared with the PL010 so we use the combined
+ * struct like u-boot does. base comes from the dtb, never hardcoded.
+ *
+ * Copyright (C) 2026 Bradley Morgan <brads@mainlining.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <sys/types.h>
+#include <stdint.h>
+#include <reg.h>
+#include <drivers/serial/pl011.h>
+
+void pl011_init(uintptr_t base, uint32 clock, uint32 baud)
+{
+	struct pl01x_regs *regs = (struct pl01x_regs *)base;
+	uint32 divisor;
+	uint32 remainder;
+	uint32 fraction;
+
+	/* baud divisor, same math as the PL011 TRM section 3.3.3 */
+	divisor = clock / (16 * baud);
+	remainder = clock % (16 * baud);
+	fraction = (8 * remainder + baud / 2) / baud;
+
+	writel(0, &regs->pl011_cr);
+	writel(0x7ff, &regs->pl011_icr);
+	writel(divisor, &regs->pl011_ibrd);
+	writel(fraction, &regs->pl011_fbrd);
+	writel((3 << 5) | (1 << 4), &regs->pl011_lcrh);
+	writel((1 << 0) | (1 << 8) | (1 << 9), &regs->pl011_cr);
+}
+
+void pl011_putc(uintptr_t base, char c)
+{
+	struct pl01x_regs *regs = (struct pl01x_regs *)base;
+
+	while (readl(&regs->fr) & UART_PL01x_FR_TXFF)
+		;
+	writel(c, &regs->dr);
+}
+
+int pl011_getc(uintptr_t base)
+{
+	struct pl01x_regs *regs = (struct pl01x_regs *)base;
+
+	if (readl(&regs->fr) & UART_PL01x_FR_RXFE)
+		return -1;
+	return readl(&regs->dr) & 0xff;
+}