1 files changed, 307 insertions, 0 deletions
diff --git a/drivers/tty/serial/8250/8250_uniphier.c b/drivers/tty/serial/8250/8250_uniphier.c
new file mode 100644
index 000000000..a2978abab
--- /dev/null
+++ b/drivers/tty/serial/8250/8250_uniphier.c
@@ -0,0 +1,307 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2015 Masahiro Yamada <yamada.masahiro@socionext.com>
+ */
+
+#include <linux/clk.h>
+#include <linux/console.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+
+#include "8250.h"
+
+/*
+ * This hardware is similar to 8250, but its register map is a bit different:
+ *   - MMIO32 (regshift = 2)
+ *   - FCR is not at 2, but 3
+ *   - LCR and MCR are not at 3 and 4, they share 4
+ *   - No SCR (Instead, CHAR can be used as a scratch register)
+ *   - Divisor latch at 9, no divisor latch access bit
+ */
+
+#define UNIPHIER_UART_REGSHIFT		2
+
+/* bit[15:8] = CHAR, bit[7:0] = FCR */
+#define UNIPHIER_UART_CHAR_FCR		(3 << (UNIPHIER_UART_REGSHIFT))
+/* bit[15:8] = LCR, bit[7:0] = MCR */
+#define UNIPHIER_UART_LCR_MCR		(4 << (UNIPHIER_UART_REGSHIFT))
+/* Divisor Latch Register */
+#define UNIPHIER_UART_DLR		(9 << (UNIPHIER_UART_REGSHIFT))
+
+struct uniphier8250_priv {
+	int line;
+	struct clk *clk;
+	spinlock_t atomic_write_lock;
+};
+
+#ifdef CONFIG_SERIAL_8250_CONSOLE
+static int __init uniphier_early_console_setup(struct earlycon_device *device,
+					       const char *options)
+{
+	if (!device->port.membase)
+		return -ENODEV;
+
+	/* This hardware always expects MMIO32 register interface. */
+	device->port.iotype = UPIO_MEM32;
+	device->port.regshift = UNIPHIER_UART_REGSHIFT;
+
+	/*
+	 * Do not touch the divisor register in early_serial8250_setup();
+	 * we assume it has been initialized by a boot loader.
+	 */
+	device->baud = 0;
+
+	return early_serial8250_setup(device, options);
+}
+OF_EARLYCON_DECLARE(uniphier, "socionext,uniphier-uart",
+		    uniphier_early_console_setup);
+#endif
+
+/*
+ * The register map is slightly different from that of 8250.
+ * IO callbacks must be overridden for correct access to FCR, LCR, MCR and SCR.
+ */
+static unsigned int uniphier_serial_in(struct uart_port *p, int offset)
+{
+	unsigned int valshift = 0;
+
+	switch (offset) {
+	case UART_SCR:
+		/* No SCR for this hardware.  Use CHAR as a scratch register */
+		valshift = 8;
+		offset = UNIPHIER_UART_CHAR_FCR;
+		break;
+	case UART_LCR:
+		valshift = 8;
+		fallthrough;
+	case UART_MCR:
+		offset = UNIPHIER_UART_LCR_MCR;
+		break;
+	default:
+		offset <<= UNIPHIER_UART_REGSHIFT;
+		break;
+	}
+
+	/*
+	 * The return value must be masked with 0xff because some registers
+	 * share the same offset that must be accessed by 32-bit write/read.
+	 * 8 or 16 bit access to this hardware result in unexpected behavior.
+	 */
+	return (readl(p->membase + offset) >> valshift) & 0xff;
+}
+
+static void uniphier_serial_out(struct uart_port *p, int offset, int value)
+{
+	unsigned int valshift = 0;
+	bool normal = false;
+
+	switch (offset) {
+	case UART_SCR:
+		/* No SCR for this hardware.  Use CHAR as a scratch register */
+		valshift = 8;
+		fallthrough;
+	case UART_FCR:
+		offset = UNIPHIER_UART_CHAR_FCR;
+		break;
+	case UART_LCR:
+		valshift = 8;
+		/* Divisor latch access bit does not exist. */
+		value &= ~UART_LCR_DLAB;
+		fallthrough;
+	case UART_MCR:
+		offset = UNIPHIER_UART_LCR_MCR;
+		break;
+	default:
+		offset <<= UNIPHIER_UART_REGSHIFT;
+		normal = true;
+		break;
+	}
+
+	if (normal) {
+		writel(value, p->membase + offset);
+	} else {
+		/*
+		 * Special case: two registers share the same address that
+		 * must be 32-bit accessed.  As this is not longer atomic safe,
+		 * take a lock just in case.
+		 */
+		struct uniphier8250_priv *priv = p->private_data;
+		unsigned long flags;
+		u32 tmp;
+
+		spin_lock_irqsave(&priv->atomic_write_lock, flags);
+		tmp = readl(p->membase + offset);
+		tmp &= ~(0xff << valshift);
+		tmp |= value << valshift;
+		writel(tmp, p->membase + offset);
+		spin_unlock_irqrestore(&priv->atomic_write_lock, flags);
+	}
+}
+
+/*
+ * This hardware does not have the divisor latch access bit.
+ * The divisor latch register exists at different address.
+ * Override dl_read/write callbacks.
+ */
+static int uniphier_serial_dl_read(struct uart_8250_port *up)
+{
+	return readl(up->port.membase + UNIPHIER_UART_DLR);
+}
+
+static void uniphier_serial_dl_write(struct uart_8250_port *up, int value)
+{
+	writel(value, up->port.membase + UNIPHIER_UART_DLR);
+}
+
+static int uniphier_uart_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct uart_8250_port up;
+	struct uniphier8250_priv *priv;
+	struct resource *regs;
+	void __iomem *membase;
+	int irq;
+	int ret;
+
+	regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!regs) {
+		dev_err(dev, "failed to get memory resource\n");
+		return -EINVAL;
+	}
+
+	membase = devm_ioremap(dev, regs->start, resource_size(regs));
+	if (!membase)
+		return -ENOMEM;
+
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0)
+		return irq;
+
+	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	memset(&up, 0, sizeof(up));
+
+	ret = of_alias_get_id(dev->of_node, "serial");
+	if (ret < 0) {
+		dev_err(dev, "failed to get alias id\n");
+		return ret;
+	}
+	up.port.line = ret;
+
+	priv->clk = devm_clk_get(dev, NULL);
+	if (IS_ERR(priv->clk)) {
+		dev_err(dev, "failed to get clock\n");
+		return PTR_ERR(priv->clk);
+	}
+
+	ret = clk_prepare_enable(priv->clk);
+	if (ret)
+		return ret;
+
+	up.port.uartclk = clk_get_rate(priv->clk);
+
+	spin_lock_init(&priv->atomic_write_lock);
+
+	up.port.dev = dev;
+	up.port.private_data = priv;
+	up.port.mapbase = regs->start;
+	up.port.mapsize = resource_size(regs);
+	up.port.membase = membase;
+	up.port.irq = irq;
+
+	up.port.type = PORT_16550A;
+	up.port.iotype = UPIO_MEM32;
+	up.port.fifosize = 64;
+	up.port.regshift = UNIPHIER_UART_REGSHIFT;
+	up.port.flags = UPF_FIXED_PORT | UPF_FIXED_TYPE;
+	up.capabilities = UART_CAP_FIFO;
+
+	if (of_property_read_bool(dev->of_node, "auto-flow-control"))
+		up.capabilities |= UART_CAP_AFE;
+
+	up.port.serial_in = uniphier_serial_in;
+	up.port.serial_out = uniphier_serial_out;
+	up.dl_read = uniphier_serial_dl_read;
+	up.dl_write = uniphier_serial_dl_write;
+
+	ret = serial8250_register_8250_port(&up);
+	if (ret < 0) {
+		dev_err(dev, "failed to register 8250 port\n");
+		clk_disable_unprepare(priv->clk);
+		return ret;
+	}
+	priv->line = ret;
+
+	platform_set_drvdata(pdev, priv);
+
+	return 0;
+}
+
+static int uniphier_uart_remove(struct platform_device *pdev)
+{
+	struct uniphier8250_priv *priv = platform_get_drvdata(pdev);
+
+	serial8250_unregister_port(priv->line);
+	clk_disable_unprepare(priv->clk);
+
+	return 0;
+}
+
+static int __maybe_unused uniphier_uart_suspend(struct device *dev)
+{
+	struct uniphier8250_priv *priv = dev_get_drvdata(dev);
+	struct uart_8250_port *up = serial8250_get_port(priv->line);
+
+	serial8250_suspend_port(priv->line);
+
+	if (!uart_console(&up->port) || console_suspend_enabled)
+		clk_disable_unprepare(priv->clk);
+
+	return 0;
+}
+
+static int __maybe_unused uniphier_uart_resume(struct device *dev)
+{
+	struct uniphier8250_priv *priv = dev_get_drvdata(dev);
+	struct uart_8250_port *up = serial8250_get_port(priv->line);
+	int ret;
+
+	if (!uart_console(&up->port) || console_suspend_enabled) {
+		ret = clk_prepare_enable(priv->clk);
+		if (ret)
+			return ret;
+	}
+
+	serial8250_resume_port(priv->line);
+
+	return 0;
+}
+
+static const struct dev_pm_ops uniphier_uart_pm_ops = {
+	SET_SYSTEM_SLEEP_PM_OPS(uniphier_uart_suspend, uniphier_uart_resume)
+};
+
+static const struct of_device_id uniphier_uart_match[] = {
+	{ .compatible = "socionext,uniphier-uart" },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, uniphier_uart_match);
+
+static struct platform_driver uniphier_uart_platform_driver = {
+	.probe		= uniphier_uart_probe,
+	.remove		= uniphier_uart_remove,
+	.driver = {
+		.name	= "uniphier-uart",
+		.of_match_table = uniphier_uart_match,
+		.pm = &uniphier_uart_pm_ops,
+	},
+};
+module_platform_driver(uniphier_uart_platform_driver);
+
+MODULE_AUTHOR("Masahiro Yamada <yamada.masahiro@socionext.com>");
+MODULE_DESCRIPTION("UniPhier UART driver");
+MODULE_LICENSE("GPL");