serial: 8250_tegra: Create Tegra specific 8250 driver

To support booting NVIDIA Tegra platforms with either Device-Tree or
ACPI, create a Tegra specific 8250 serial driver that supports both
firmware types. Another benefit from doing this, is that the Tegra
specific codec in the generic Open Firmware 8250 driver can now be
removed.

Signed-off-by: Jeff Brasen <jbrasen@nvidia.com>
Signed-off-by: Jon Hunter <jonathanh@nvidia.com>
Link: https://lore.kernel.org/r/20200129132817.26343-1-jonathanh@nvidia.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/8250/8250_of.c

@@ -7,7 +7,6 @@
 #include <linux/console.h>
 #include <linux/module.h>
 #include <linux/slab.h>
-#include <linux/delay.h>
 #include <linux/serial_core.h>
 #include <linux/serial_reg.h>
 #include <linux/of_address.h>
@@ -26,28 +25,6 @@ struct of_serial_info {
 	int line;
 };
 
-#ifdef CONFIG_ARCH_TEGRA
-static void tegra_serial_handle_break(struct uart_port *p)
-{
-	unsigned int status, tmout = 10000;
-
-	do {
-		status = p->serial_in(p, UART_LSR);
-		if (status & (UART_LSR_FIFOE | UART_LSR_BRK_ERROR_BITS))
-			status = p->serial_in(p, UART_RX);
-		else
-			break;
-		if (--tmout == 0)
-			break;
-		udelay(1);
-	} while (1);
-}
-#else
-static inline void tegra_serial_handle_break(struct uart_port *port)
-{
-}
-#endif
-
 static int of_8250_rs485_config(struct uart_port *port,
 				  struct serial_rs485 *rs485)
 {
@@ -211,10 +188,6 @@ static int of_platform_serial_setup(struct platform_device *ofdev,
 	port->rs485_config = of_8250_rs485_config;
 
 	switch (type) {
-	case PORT_TEGRA:
-		port->handle_break = tegra_serial_handle_break;
-		break;
-
 	case PORT_RT2880:
 		port->iotype = UPIO_AU;
 		break;
@@ -359,7 +332,6 @@ static const struct of_device_id of_platform_serial_table[] = {
 	{ .compatible = "ns16550",  .data = (void *)PORT_16550, },
 	{ .compatible = "ns16750",  .data = (void *)PORT_16750, },
 	{ .compatible = "ns16850",  .data = (void *)PORT_16850, },
-	{ .compatible = "nvidia,tegra20-uart", .data = (void *)PORT_TEGRA, },
 	{ .compatible = "nxp,lpc3220-uart", .data = (void *)PORT_LPC3220, },
 	{ .compatible = "ralink,rt2880-uart", .data = (void *)PORT_RT2880, },
 	{ .compatible = "intel,xscale-uart", .data = (void *)PORT_XSCALE, },

drivers/tty/serial/8250/8250_tegra.c

@@ -0,0 +1,198 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ *  Serial Port driver for Tegra devices
+ *
+ *  Copyright (c) 2020, NVIDIA CORPORATION. All rights reserved.
+ */
+
+#include <linux/acpi.h>
+#include <linux/clk.h>
+#include <linux/console.h>
+#include <linux/delay.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/reset.h>
+#include <linux/slab.h>
+
+#include "8250.h"
+
+struct tegra_uart {
+	struct clk *clk;
+	struct reset_control *rst;
+	int line;
+};
+
+static void tegra_uart_handle_break(struct uart_port *p)
+{
+	unsigned int status, tmout = 10000;
+
+	do {
+		status = p->serial_in(p, UART_LSR);
+		if (status & (UART_LSR_FIFOE | UART_LSR_BRK_ERROR_BITS))
+			status = p->serial_in(p, UART_RX);
+		else
+			break;
+		if (--tmout == 0)
+			break;
+		udelay(1);
+	} while (1);
+}
+
+static int tegra_uart_probe(struct platform_device *pdev)
+{
+	struct uart_8250_port port8250;
+	struct tegra_uart *uart;
+	struct uart_port *port;
+	struct resource *res;
+	int ret;
+
+	uart = devm_kzalloc(&pdev->dev, sizeof(*uart), GFP_KERNEL);
+	if (!uart)
+		return -ENOMEM;
+
+	memset(&port8250, 0, sizeof(port8250));
+
+	port = &port8250.port;
+	spin_lock_init(&port->lock);
+
+	port->flags = UPF_SHARE_IRQ | UPF_BOOT_AUTOCONF | UPF_FIXED_PORT |
+		      UPF_FIXED_TYPE;
+	port->iotype = UPIO_MEM32;
+	port->regshift = 2;
+	port->type = PORT_TEGRA;
+	port->irqflags |= IRQF_SHARED;
+	port->dev = &pdev->dev;
+	port->handle_break = tegra_uart_handle_break;
+
+	ret = of_alias_get_id(pdev->dev.of_node, "serial");
+	if (ret >= 0)
+		port->line = ret;
+
+	ret = platform_get_irq(pdev, 0);
+	if (ret < 0)
+		return ret;
+
+	port->irq = ret;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res)
+		return -ENODEV;
+
+	port->membase = devm_ioremap(&pdev->dev, res->start,
+				     resource_size(res));
+	if (!port->membase)
+		return -ENOMEM;
+
+	port->mapbase = res->start;
+	port->mapsize = resource_size(res);
+
+	uart->rst = devm_reset_control_get_optional_shared(&pdev->dev, NULL);
+	if (IS_ERR(uart->rst))
+		return PTR_ERR(uart->rst);
+
+	if (device_property_read_u32(&pdev->dev, "clock-frequency",
+				     &port->uartclk)) {
+		uart->clk = devm_clk_get(&pdev->dev, NULL);
+		if (IS_ERR(uart->clk)) {
+			dev_err(&pdev->dev, "failed to get clock!\n");
+			return -ENODEV;
+		}
+
+		ret = clk_prepare_enable(uart->clk);
+		if (ret < 0)
+			return ret;
+
+		port->uartclk = clk_get_rate(uart->clk);
+	}
+
+	ret = reset_control_deassert(uart->rst);
+	if (ret)
+		goto err_clkdisable;
+
+	ret = serial8250_register_8250_port(&port8250);
+	if (ret < 0)
+		goto err_clkdisable;
+
+	platform_set_drvdata(pdev, uart);
+	uart->line = ret;
+
+	return 0;
+
+err_clkdisable:
+	clk_disable_unprepare(uart->clk);
+
+	return ret;
+}
+
+static int tegra_uart_remove(struct platform_device *pdev)
+{
+	struct tegra_uart *uart = platform_get_drvdata(pdev);
+
+	serial8250_unregister_port(uart->line);
+	reset_control_assert(uart->rst);
+	clk_disable_unprepare(uart->clk);
+
+	return 0;
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int tegra_uart_suspend(struct device *dev)
+{
+	struct tegra_uart *uart = dev_get_drvdata(dev);
+	struct uart_8250_port *port8250 = serial8250_get_port(uart->line);
+	struct uart_port *port = &port8250->port;
+
+	serial8250_suspend_port(uart->line);
+
+	if (!uart_console(port) || console_suspend_enabled)
+		clk_disable_unprepare(uart->clk);
+
+	return 0;
+}
+
+static int tegra_uart_resume(struct device *dev)
+{
+	struct tegra_uart *uart = dev_get_drvdata(dev);
+	struct uart_8250_port *port8250 = serial8250_get_port(uart->line);
+	struct uart_port *port = &port8250->port;
+
+	if (!uart_console(port) || console_suspend_enabled)
+		clk_prepare_enable(uart->clk);
+
+	serial8250_resume_port(uart->line);
+
+	return 0;
+}
+#endif
+
+static SIMPLE_DEV_PM_OPS(tegra_uart_pm_ops, tegra_uart_suspend,
+			 tegra_uart_resume);
+
+static const struct of_device_id tegra_uart_of_match[] = {
+	{ .compatible = "nvidia,tegra20-uart", },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, tegra_uart_of_match);
+
+static const struct acpi_device_id tegra_uart_acpi_match[] = {
+	{ "NVDA0100", 0 },
+	{ },
+};
+MODULE_DEVICE_TABLE(acpi, tegra_uart_acpi_match);
+
+static struct platform_driver tegra_uart_driver = {
+	.driver = {
+		.name = "tegra-uart",
+		.pm = &tegra_uart_pm_ops,
+		.of_match_table = tegra_uart_of_match,
+		.acpi_match_table = ACPI_PTR(tegra_uart_acpi_match),
+	},
+	.probe = tegra_uart_probe,
+	.remove = tegra_uart_remove,
+};
+
+module_platform_driver(tegra_uart_driver);
+
+MODULE_AUTHOR("Jeff Brasen <jbrasen@nvidia.com>");
+MODULE_DESCRIPTION("NVIDIA Tegra 8250 Driver");
+MODULE_LICENSE("GPL v2");

drivers/tty/serial/8250/Kconfig

@@ -500,6 +500,15 @@ config SERIAL_8250_PXA
 	  applicable to both devicetree and legacy boards, and early console is
 	  part of its support.
 
+config SERIAL_8250_TEGRA
+	tristate "8250 support for Tegra serial ports"
+	default SERIAL_8250
+	depends on SERIAL_8250
+	depends on ARCH_TEGRA || COMPILE_TEST
+	help
+	  Select this option if you have machine with an NVIDIA Tegra SoC and
+	  wish to enable 8250 serial driver for the Tegra serial interfaces.
+
 config SERIAL_OF_PLATFORM
 	tristate "Devicetree based probing for 8250 ports"
 	depends on SERIAL_8250 && OF

drivers/tty/serial/8250/Makefile

@@ -37,6 +37,7 @@ obj-$(CONFIG_SERIAL_8250_INGENIC)	+= 8250_ingenic.o
 obj-$(CONFIG_SERIAL_8250_LPSS)		+= 8250_lpss.o
 obj-$(CONFIG_SERIAL_8250_MID)		+= 8250_mid.o
 obj-$(CONFIG_SERIAL_8250_PXA)		+= 8250_pxa.o
+obj-$(CONFIG_SERIAL_8250_TEGRA)		+= 8250_tegra.o
 obj-$(CONFIG_SERIAL_OF_PLATFORM)	+= 8250_of.o
 
 CFLAGS_8250_ingenic.o += -I$(srctree)/scripts/dtc/libfdt