Linux-libre 4.5-gnu

9 files changed, 425 insertions, 54 deletions

diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c
index 58dbff93a..279a842cd 100644
--- a/drivers/tty/serial/8250/8250_core.c
+++ b/drivers/tty/serial/8250/8250_core.c
@@ -620,7 +620,7 @@ static int univ8250_console_setup(struct console *co, char *options)
  *	@options: ptr to option string from console command line
  *
  *	Only attempts to match console command lines of the form:
- *	    console=uart[8250],io|mmio|mmio32,<addr>[,<options>]
+ *	    console=uart[8250],io|mmio|mmio16|mmio32,<addr>[,<options>]
  *	    console=uart[8250],0x<addr>[,<options>]
  *	This form is used to register an initial earlycon boot console and
  *	replace it with the serial8250_console at 8250 driver init.
@@ -650,8 +650,9 @@ static int univ8250_console_match(struct console *co, char *name, int idx,
 
 		if (port->iotype != iotype)
 			continue;
-		if ((iotype == UPIO_MEM || iotype == UPIO_MEM32) &&
-		    (port->mapbase != addr))
+		if ((iotype == UPIO_MEM || iotype == UPIO_MEM16 ||
+		     iotype == UPIO_MEM32 || iotype == UPIO_MEM32BE)
+		    && (port->mapbase != addr))
 			continue;
 		if (iotype == UPIO_PORT && port->iobase != addr)
 			continue;
diff --git a/drivers/tty/serial/8250/8250_early.c b/drivers/tty/serial/8250/8250_early.c
index e2919b4d1..2aa151366 100644
--- a/drivers/tty/serial/8250/8250_early.c
+++ b/drivers/tty/serial/8250/8250_early.c
@@ -42,6 +42,8 @@ static unsigned int __init serial8250_early_in(struct uart_port *port, int offse
 	switch (port->iotype) {
 	case UPIO_MEM:
 		return readb(port->membase + offset);
+	case UPIO_MEM16:
+		return readw(port->membase + (offset << 1));
 	case UPIO_MEM32:
 		return readl(port->membase + (offset << 2));
 	case UPIO_MEM32BE:
@@ -59,6 +61,9 @@ static void __init serial8250_early_out(struct uart_port *port, int offset, int
 	case UPIO_MEM:
 		writeb(value, port->membase + offset);
 		break;
+	case UPIO_MEM16:
+		writew(value, port->membase + (offset << 1));
+		break;
 	case UPIO_MEM32:
 		writel(value, port->membase + (offset << 2));
 		break;
@@ -73,43 +78,27 @@ static void __init serial8250_early_out(struct uart_port *port, int offset, int
 
 #define BOTH_EMPTY (UART_LSR_TEMT | UART_LSR_THRE)
 
-static void __init wait_for_xmitr(struct uart_port *port)
+static void __init serial_putc(struct uart_port *port, int c)
 {
 	unsigned int status;
 
+	serial8250_early_out(port, UART_TX, c);
+
 	for (;;) {
 		status = serial8250_early_in(port, UART_LSR);
 		if ((status & BOTH_EMPTY) == BOTH_EMPTY)
-			return;
+			break;
 		cpu_relax();
 	}
 }
 
-static void __init serial_putc(struct uart_port *port, int c)
-{
-	wait_for_xmitr(port);
-	serial8250_early_out(port, UART_TX, c);
-}
-
 static void __init early_serial8250_write(struct console *console,
           const char *s, unsigned int count, unsigned int loglevel)
 {
 	struct earlycon_device *device = console->data;
 	struct uart_port *port = &device->port;
-	unsigned int ier;
-
-	/* Save the IER and disable interrupts preserving the UUE bit */
-	ier = serial8250_early_in(port, UART_IER);
-	if (ier)
-		serial8250_early_out(port, UART_IER, ier & UART_IER_UUE);
 
 	uart_console_write(port, s, count, serial_putc);
-
-	/* Wait for transmitter to become empty and restore the IER */
-	wait_for_xmitr(port);
-
-	if (ier)
-		serial8250_early_out(port, UART_IER, ier);
 }
 
 static void __init init_port(struct earlycon_device *device)
diff --git a/drivers/tty/serial/8250/8250_ingenic.c b/drivers/tty/serial/8250/8250_ingenic.c
index 49394b4c5..d6e1ec9b4 100644
--- a/drivers/tty/serial/8250/8250_ingenic.c
+++ b/drivers/tty/serial/8250/8250_ingenic.c
@@ -48,6 +48,7 @@ static const struct of_device_id of_match[];
 #define UART_MCR_MDCE	BIT(7)
 #define UART_MCR_FCM	BIT(6)
 
+#ifdef CONFIG_SERIAL_EARLYCON
 static struct earlycon_device *early_device;
 
 static uint8_t __init early_in(struct uart_port *port, int offset)
@@ -140,6 +141,7 @@ OF_EARLYCON_DECLARE(jz4775_uart, "ingenic,jz4775-uart",
 EARLYCON_DECLARE(jz4780_uart, ingenic_early_console_setup);
 OF_EARLYCON_DECLARE(jz4780_uart, "ingenic,jz4780-uart",
 		    ingenic_early_console_setup);
+#endif /* CONFIG_SERIAL_EARLYCON */
 
 static void ingenic_uart_serial_out(struct uart_port *p, int offset, int value)
 {
diff --git a/drivers/tty/serial/8250/8250_mtk.c b/drivers/tty/serial/8250/8250_mtk.c
index 78883ca64..0e590b233 100644
--- a/drivers/tty/serial/8250/8250_mtk.c
+++ b/drivers/tty/serial/8250/8250_mtk.c
@@ -16,7 +16,7 @@
  */
 #include <linux/clk.h>
 #include <linux/io.h>
-#include <linux/module.h>
+#include <linux/init.h>
 #include <linux/of_irq.h>
 #include <linux/of_platform.h>
 #include <linux/platform_device.h>
@@ -245,23 +245,6 @@ static int mtk8250_probe(struct platform_device *pdev)
 	return 0;
 }
 
-static int mtk8250_remove(struct platform_device *pdev)
-{
-	struct mtk8250_data *data = platform_get_drvdata(pdev);
-
-	pm_runtime_get_sync(&pdev->dev);
-
-	serial8250_unregister_port(data->line);
-
-	pm_runtime_disable(&pdev->dev);
-	pm_runtime_put_noidle(&pdev->dev);
-
-	if (!pm_runtime_status_suspended(&pdev->dev))
-		mtk8250_runtime_suspend(&pdev->dev);
-
-	return 0;
-}
-
 #ifdef CONFIG_PM_SLEEP
 static int mtk8250_suspend(struct device *dev)
 {
@@ -292,18 +275,18 @@ static const struct of_device_id mtk8250_of_match[] = {
 	{ .compatible = "mediatek,mt6577-uart" },
 	{ /* Sentinel */ }
 };
-MODULE_DEVICE_TABLE(of, mtk8250_of_match);
 
 static struct platform_driver mtk8250_platform_driver = {
 	.driver = {
-		.name		= "mt6577-uart",
-		.pm		= &mtk8250_pm_ops,
-		.of_match_table	= mtk8250_of_match,
+		.name			= "mt6577-uart",
+		.pm			= &mtk8250_pm_ops,
+		.of_match_table		= mtk8250_of_match,
+		.suppress_bind_attrs	= true,
+
 	},
 	.probe			= mtk8250_probe,
-	.remove			= mtk8250_remove,
 };
-module_platform_driver(mtk8250_platform_driver);
+builtin_platform_driver(mtk8250_platform_driver);
 
 #ifdef CONFIG_SERIAL_8250_CONSOLE
 static int __init early_mtk8250_setup(struct earlycon_device *device,
@@ -319,7 +302,3 @@ static int __init early_mtk8250_setup(struct earlycon_device *device,
 
 OF_EARLYCON_DECLARE(mtk8250, "mediatek,mt6577-uart", early_mtk8250_setup);
 #endif
-
-MODULE_AUTHOR("Matthias Brugger");
-MODULE_LICENSE("GPL");
-MODULE_DESCRIPTION("Mediatek 8250 serial port driver");
diff --git a/drivers/tty/serial/8250/8250_of.c b/drivers/tty/serial/8250/8250_of.c
new file mode 100644
index 000000000..33021c1f7
--- /dev/null
+++ b/drivers/tty/serial/8250/8250_of.c
@@ -0,0 +1,347 @@
+/*
+ *  Serial Port driver for Open Firmware platform devices
+ *
+ *    Copyright (C) 2006 Arnd Bergmann <arnd@arndb.de>, IBM Corp.
+ *
+ *  This program is free software; you can redistribute it and/or
+ *  modify it under the terms of the GNU General Public License
+ *  as published by the Free Software Foundation; either version
+ *  2 of the License, or (at your option) any later version.
+ *
+ */
+#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>
+#include <linux/of_irq.h>
+#include <linux/of_platform.h>
+#include <linux/clk.h>
+
+#include "8250.h"
+
+struct of_serial_info {
+	struct clk *clk;
+	int type;
+	int line;
+};
+
+#ifdef CONFIG_ARCH_TEGRA
+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
+
+/*
+ * Fill a struct uart_port for a given device node
+ */
+static int of_platform_serial_setup(struct platform_device *ofdev,
+			int type, struct uart_port *port,
+			struct of_serial_info *info)
+{
+	struct resource resource;
+	struct device_node *np = ofdev->dev.of_node;
+	u32 clk, spd, prop;
+	int ret;
+
+	memset(port, 0, sizeof *port);
+	if (of_property_read_u32(np, "clock-frequency", &clk)) {
+
+		/* Get clk rate through clk driver if present */
+		info->clk = devm_clk_get(&ofdev->dev, NULL);
+		if (IS_ERR(info->clk)) {
+			dev_warn(&ofdev->dev,
+				"clk or clock-frequency not defined\n");
+			return PTR_ERR(info->clk);
+		}
+
+		ret = clk_prepare_enable(info->clk);
+		if (ret < 0)
+			return ret;
+
+		clk = clk_get_rate(info->clk);
+	}
+	/* If current-speed was set, then try not to change it. */
+	if (of_property_read_u32(np, "current-speed", &spd) == 0)
+		port->custom_divisor = clk / (16 * spd);
+
+	ret = of_address_to_resource(np, 0, &resource);
+	if (ret) {
+		dev_warn(&ofdev->dev, "invalid address\n");
+		goto out;
+	}
+
+	spin_lock_init(&port->lock);
+	port->mapbase = resource.start;
+	port->mapsize = resource_size(&resource);
+
+	/* Check for shifted address mapping */
+	if (of_property_read_u32(np, "reg-offset", &prop) == 0)
+		port->mapbase += prop;
+
+	/* Check for registers offset within the devices address range */
+	if (of_property_read_u32(np, "reg-shift", &prop) == 0)
+		port->regshift = prop;
+
+	/* Check for fifo size */
+	if (of_property_read_u32(np, "fifo-size", &prop) == 0)
+		port->fifosize = prop;
+
+	/* Check for a fixed line number */
+	ret = of_alias_get_id(np, "serial");
+	if (ret >= 0)
+		port->line = ret;
+
+	port->irq = irq_of_parse_and_map(np, 0);
+	port->iotype = UPIO_MEM;
+	if (of_property_read_u32(np, "reg-io-width", &prop) == 0) {
+		switch (prop) {
+		case 1:
+			port->iotype = UPIO_MEM;
+			break;
+		case 2:
+			port->iotype = UPIO_MEM16;
+			break;
+		case 4:
+			port->iotype = of_device_is_big_endian(np) ?
+				       UPIO_MEM32BE : UPIO_MEM32;
+			break;
+		default:
+			dev_warn(&ofdev->dev, "unsupported reg-io-width (%d)\n",
+				 prop);
+			ret = -EINVAL;
+			goto out;
+		}
+	}
+
+	port->type = type;
+	port->uartclk = clk;
+	port->flags = UPF_SHARE_IRQ | UPF_BOOT_AUTOCONF | UPF_IOREMAP
+		| UPF_FIXED_PORT | UPF_FIXED_TYPE;
+
+	if (of_find_property(np, "no-loopback-test", NULL))
+		port->flags |= UPF_SKIP_TEST;
+
+	port->dev = &ofdev->dev;
+
+	switch (type) {
+	case PORT_TEGRA:
+		port->handle_break = tegra_serial_handle_break;
+		break;
+
+	case PORT_RT2880:
+		port->iotype = UPIO_AU;
+		break;
+	}
+
+	if (IS_ENABLED(CONFIG_SERIAL_8250_FSL) &&
+	    (of_device_is_compatible(np, "fsl,ns16550") ||
+	     of_device_is_compatible(np, "fsl,16550-FIFO64")))
+		port->handle_irq = fsl8250_handle_irq;
+
+	return 0;
+out:
+	if (info->clk)
+		clk_disable_unprepare(info->clk);
+	return ret;
+}
+
+/*
+ * Try to register a serial port
+ */
+static const struct of_device_id of_platform_serial_table[];
+static int of_platform_serial_probe(struct platform_device *ofdev)
+{
+	const struct of_device_id *match;
+	struct of_serial_info *info;
+	struct uart_port port;
+	int port_type;
+	int ret;
+
+	match = of_match_device(of_platform_serial_table, &ofdev->dev);
+	if (!match)
+		return -EINVAL;
+
+	if (of_find_property(ofdev->dev.of_node, "used-by-rtas", NULL))
+		return -EBUSY;
+
+	info = kzalloc(sizeof(*info), GFP_KERNEL);
+	if (info == NULL)
+		return -ENOMEM;
+
+	port_type = (unsigned long)match->data;
+	ret = of_platform_serial_setup(ofdev, port_type, &port, info);
+	if (ret)
+		goto out;
+
+	switch (port_type) {
+	case PORT_8250 ... PORT_MAX_8250:
+	{
+		struct uart_8250_port port8250;
+		memset(&port8250, 0, sizeof(port8250));
+		port8250.port = port;
+
+		if (port.fifosize)
+			port8250.capabilities = UART_CAP_FIFO;
+
+		if (of_property_read_bool(ofdev->dev.of_node,
+					  "auto-flow-control"))
+			port8250.capabilities |= UART_CAP_AFE;
+
+		ret = serial8250_register_8250_port(&port8250);
+		break;
+	}
+	default:
+		/* need to add code for these */
+	case PORT_UNKNOWN:
+		dev_info(&ofdev->dev, "Unknown serial port found, ignored\n");
+		ret = -ENODEV;
+		break;
+	}
+	if (ret < 0)
+		goto out;
+
+	info->type = port_type;
+	info->line = ret;
+	platform_set_drvdata(ofdev, info);
+	return 0;
+out:
+	kfree(info);
+	irq_dispose_mapping(port.irq);
+	return ret;
+}
+
+/*
+ * Release a line
+ */
+static int of_platform_serial_remove(struct platform_device *ofdev)
+{
+	struct of_serial_info *info = platform_get_drvdata(ofdev);
+	switch (info->type) {
+	case PORT_8250 ... PORT_MAX_8250:
+		serial8250_unregister_port(info->line);
+		break;
+	default:
+		/* need to add code for these */
+		break;
+	}
+
+	if (info->clk)
+		clk_disable_unprepare(info->clk);
+	kfree(info);
+	return 0;
+}
+
+#ifdef CONFIG_PM_SLEEP
+static void of_serial_suspend_8250(struct of_serial_info *info)
+{
+	struct uart_8250_port *port8250 = serial8250_get_port(info->line);
+	struct uart_port *port = &port8250->port;
+
+	serial8250_suspend_port(info->line);
+	if (info->clk && (!uart_console(port) || console_suspend_enabled))
+		clk_disable_unprepare(info->clk);
+}
+
+static void of_serial_resume_8250(struct of_serial_info *info)
+{
+	struct uart_8250_port *port8250 = serial8250_get_port(info->line);
+	struct uart_port *port = &port8250->port;
+
+	if (info->clk && (!uart_console(port) || console_suspend_enabled))
+		clk_prepare_enable(info->clk);
+
+	serial8250_resume_port(info->line);
+}
+
+static int of_serial_suspend(struct device *dev)
+{
+	struct of_serial_info *info = dev_get_drvdata(dev);
+
+	switch (info->type) {
+	case PORT_8250 ... PORT_MAX_8250:
+		of_serial_suspend_8250(info);
+		break;
+	default:
+		break;
+	}
+
+	return 0;
+}
+
+static int of_serial_resume(struct device *dev)
+{
+	struct of_serial_info *info = dev_get_drvdata(dev);
+
+	switch (info->type) {
+	case PORT_8250 ... PORT_MAX_8250:
+		of_serial_resume_8250(info);
+		break;
+	default:
+		break;
+	}
+
+	return 0;
+}
+#endif
+static SIMPLE_DEV_PM_OPS(of_serial_pm_ops, of_serial_suspend, of_serial_resume);
+
+/*
+ * A few common types, add more as needed.
+ */
+static const struct of_device_id of_platform_serial_table[] = {
+	{ .compatible = "ns8250",   .data = (void *)PORT_8250, },
+	{ .compatible = "ns16450",  .data = (void *)PORT_16450, },
+	{ .compatible = "ns16550a", .data = (void *)PORT_16550A, },
+	{ .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 = "altr,16550-FIFO32",
+		.data = (void *)PORT_ALTR_16550_F32, },
+	{ .compatible = "altr,16550-FIFO64",
+		.data = (void *)PORT_ALTR_16550_F64, },
+	{ .compatible = "altr,16550-FIFO128",
+		.data = (void *)PORT_ALTR_16550_F128, },
+	{ .compatible = "mrvl,mmp-uart",
+		.data = (void *)PORT_XSCALE, },
+	{ .compatible = "mrvl,pxa-uart",
+		.data = (void *)PORT_XSCALE, },
+	{ /* end of list */ },
+};
+MODULE_DEVICE_TABLE(of, of_platform_serial_table);
+
+static struct platform_driver of_platform_serial_driver = {
+	.driver = {
+		.name = "of_serial",
+		.of_match_table = of_platform_serial_table,
+	},
+	.probe = of_platform_serial_probe,
+	.remove = of_platform_serial_remove,
+};
+
+module_platform_driver(of_platform_serial_driver);
+
+MODULE_AUTHOR("Arnd Bergmann <arnd@arndb.de>");
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Serial Port driver for Open Firmware platform devices");
diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
index 5a85bbaa2..83aed6193 100644
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -368,6 +368,18 @@ static void mem_serial_out(struct uart_port *p, int offset, int value)
 	writeb(value, p->membase + offset);
 }
 
+static void mem16_serial_out(struct uart_port *p, int offset, int value)
+{
+	offset = offset << p->regshift;
+	writew(value, p->membase + offset);
+}
+
+static unsigned int mem16_serial_in(struct uart_port *p, int offset)
+{
+	offset = offset << p->regshift;
+	return readw(p->membase + offset);
+}
+
 static void mem32_serial_out(struct uart_port *p, int offset, int value)
 {
 	offset = offset << p->regshift;
@@ -425,6 +437,11 @@ static void set_io_from_upio(struct uart_port *p)
 		p->serial_out = mem_serial_out;
 		break;
 
+	case UPIO_MEM16:
+		p->serial_in = mem16_serial_in;
+		p->serial_out = mem16_serial_out;
+		break;
+
 	case UPIO_MEM32:
 		p->serial_in = mem32_serial_in;
 		p->serial_out = mem32_serial_out;
@@ -459,6 +476,7 @@ serial_port_out_sync(struct uart_port *p, int offset, int value)
 {
 	switch (p->iotype) {
 	case UPIO_MEM:
+	case UPIO_MEM16:
 	case UPIO_MEM32:
 	case UPIO_MEM32BE:
 	case UPIO_AU:
@@ -2462,6 +2480,7 @@ static int serial8250_request_std_resource(struct uart_8250_port *up)
 	case UPIO_TSI:
 	case UPIO_MEM32:
 	case UPIO_MEM32BE:
+	case UPIO_MEM16:
 	case UPIO_MEM:
 		if (!port->mapbase)
 			break;
@@ -2499,6 +2518,7 @@ static void serial8250_release_std_resource(struct uart_8250_port *up)
 	case UPIO_TSI:
 	case UPIO_MEM32:
 	case UPIO_MEM32BE:
+	case UPIO_MEM16:
 	case UPIO_MEM:
 		if (!port->mapbase)
 			break;
diff --git a/drivers/tty/serial/8250/8250_uniphier.c b/drivers/tty/serial/8250/8250_uniphier.c
index 245edbb68..bab6b3ae2 100644
--- a/drivers/tty/serial/8250/8250_uniphier.c
+++ b/drivers/tty/serial/8250/8250_uniphier.c
@@ -13,6 +13,7 @@
  */
 
 #include <linux/clk.h>
+#include <linux/console.h>
 #include <linux/io.h>
 #include <linux/module.h>
 #include <linux/of.h>
@@ -34,6 +35,29 @@ struct uniphier8250_priv {
 	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 = 2;
+
+	/*
+	 * 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, and MCR.
diff --git a/drivers/tty/serial/8250/Kconfig b/drivers/tty/serial/8250/Kconfig
index 6412f1455..b03cb5175 100644
--- a/drivers/tty/serial/8250/Kconfig
+++ b/drivers/tty/serial/8250/Kconfig
@@ -361,9 +361,8 @@ config SERIAL_8250_UNIPHIER
 
 config SERIAL_8250_INGENIC
 	bool "Support for Ingenic SoC serial ports"
-	depends on SERIAL_8250_CONSOLE && OF_FLATTREE
+	depends on OF_FLATTREE
 	select LIBFDT
-	select SERIAL_EARLYCON
 	help
 	  If you have a system using an Ingenic SoC and wish to make use of
 	  its UARTs, say Y to this option. If unsure, say N.
@@ -372,9 +371,18 @@ config SERIAL_8250_MID
 	tristate "Support for serial ports on Intel MID platforms"
 	depends on SERIAL_8250 && PCI
 	select HSU_DMA if SERIAL_8250_DMA
-	select HSU_DMA_PCI if X86_INTEL_MID
+	select HSU_DMA_PCI if (HSU_DMA && X86_INTEL_MID)
 	select RATIONAL
 	help
 	  Selecting this option will enable handling of the extra features
 	  present on the UART found on Intel Medfield SOC and various other
 	  Intel platforms.
+
+config SERIAL_OF_PLATFORM
+	tristate "Devicetree based probing for 8250 ports"
+	depends on SERIAL_8250 && OF
+	help
+	  This option is used for all 8250 compatible serial ports that
+	  are probed through devicetree, including Open Firmware based
+	  PowerPC systems and embedded systems on architectures using the
+	  flattened device tree format.
diff --git a/drivers/tty/serial/8250/Makefile b/drivers/tty/serial/8250/Makefile
index e177f8681..b9b9bca5b 100644
--- a/drivers/tty/serial/8250/Makefile
+++ b/drivers/tty/serial/8250/Makefile
@@ -28,5 +28,6 @@ obj-$(CONFIG_SERIAL_8250_MT6577)	+= 8250_mtk.o
 obj-$(CONFIG_SERIAL_8250_UNIPHIER)	+= 8250_uniphier.o
 obj-$(CONFIG_SERIAL_8250_INGENIC)	+= 8250_ingenic.o
 obj-$(CONFIG_SERIAL_8250_MID)		+= 8250_mid.o
+obj-$(CONFIG_SERIAL_OF_PLATFORM)	+= 8250_of.o
 
 CFLAGS_8250_ingenic.o += -I$(srctree)/scripts/dtc/libfdt