1 files changed, 100 insertions, 0 deletions
diff --git a/drivers/serial/serial_litex.c b/drivers/serial/serial_litex.c
new file mode 100644
index 0000000000..04da556f6a
--- /dev/null
+++ b/drivers/serial/serial_litex.c
@@ -0,0 +1,100 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2019 Antony Pavlov <antonynpavlov@gmail.com>
+ *
+ */
+
+#include <common.h>
+#include <init.h>
+#include <io.h>
+
+#define UART_RXTX	0x00
+#define UART_TXFULL	0x04
+#define UART_RXEMPTY	0x08
+#define UART_EV_PENDING	0x10
+#define  UART_EV_RX	(1 << 1)
+
+static inline uint32_t litex_serial_readb(struct console_device *cdev,
+						uint32_t offset)
+{
+	void __iomem *base = cdev->dev->priv;
+
+	return readb(base + offset);
+}
+
+static inline void litex_serial_writeb(struct console_device *cdev,
+					uint32_t value, uint32_t offset)
+{
+	void __iomem *base = cdev->dev->priv;
+
+	writeb(value, base + offset);
+}
+
+static void litex_serial_putc(struct console_device *cdev, char c)
+{
+	while (litex_serial_readb(cdev, UART_TXFULL))
+		;
+
+	litex_serial_writeb(cdev, c, UART_RXTX);
+}
+
+static int litex_serial_getc(struct console_device *cdev)
+{
+	int c;
+
+	while (litex_serial_readb(cdev, UART_RXEMPTY))
+		;
+
+	c = litex_serial_readb(cdev, UART_RXTX);
+
+	/* refresh UART_RXEMPTY by writing UART_EV_RX to UART_EV_PENDING */
+	litex_serial_writeb(cdev, UART_EV_RX, UART_EV_PENDING);
+
+	return c;
+}
+
+static int litex_serial_tstc(struct console_device *cdev)
+{
+	return !litex_serial_readb(cdev, UART_RXEMPTY);
+}
+
+static int litex_serial_probe(struct device *dev)
+{
+	struct resource *iores;
+	struct console_device *cdev;
+
+	cdev = xzalloc(sizeof(struct console_device));
+	iores = dev_request_mem_resource(dev, 0);
+	if (IS_ERR(iores))
+		return PTR_ERR(iores);
+
+	dev->priv = IOMEM(iores->start);
+	cdev->dev = dev;
+	cdev->tstc = &litex_serial_tstc;
+	cdev->putc = &litex_serial_putc;
+	cdev->getc = &litex_serial_getc;
+	cdev->setbrg = NULL;
+	cdev->linux_console_name = "ttyLXU";
+	cdev->linux_earlycon_name = "liteuart";
+	cdev->phys_base = IOMEM(iores->start);
+
+	console_register(cdev);
+
+	return 0;
+}
+
+static __maybe_unused struct of_device_id litex_serial_dt_ids[] = {
+	{
+		.compatible = "litex,uart",
+	}, {
+		/* sentinel */
+	}
+};
+MODULE_DEVICE_TABLE(of, litex_serial_dt_ids);
+
+static struct driver litex_serial_driver = {
+	.name  = "litex-uart",
+	.probe = litex_serial_probe,
+	.of_compatible = DRV_OF_COMPAT(litex_serial_dt_ids),
+};
+console_platform_driver(litex_serial_driver);