1 files changed, 330 insertions, 0 deletions
diff --git a/drivers/tty/serial/earlycon.c b/drivers/tty/serial/earlycon.c
new file mode 100644
index 0000000000..a5fbb6ed38
--- /dev/null
+++ b/drivers/tty/serial/earlycon.c
@@ -0,0 +1,330 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2014 Linaro Ltd.
+ * Author: Rob Herring <robh@kernel.org>
+ *
+ * Based on 8250 earlycon:
+ * (c) Copyright 2004 Hewlett-Packard Development Company, L.P.
+ *	Bjorn Helgaas <bjorn.helgaas@hp.com>
+ */
+
+#define pr_fmt(fmt)	KBUILD_MODNAME ": " fmt
+
+#include <linux/console.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/serial_core.h>
+#include <linux/sizes.h>
+#include <linux/of.h>
+#include <linux/of_fdt.h>
+#include <linux/acpi.h>
+
+#ifdef CONFIG_FIX_EARLYCON_MEM
+#include <asm/fixmap.h>
+#endif
+
+#include <asm/serial.h>
+
+static struct console early_con = {
+	.name =		"uart",		/* fixed up at earlycon registration */
+	.flags =	CON_PRINTBUFFER | CON_BOOT,
+	.index =	0,
+};
+
+static struct earlycon_device early_console_dev = {
+	.con = &early_con,
+};
+
+static void __iomem * __init earlycon_map(resource_size_t paddr, size_t size)
+{
+	void __iomem *base;
+#ifdef CONFIG_FIX_EARLYCON_MEM
+	set_fixmap_io(FIX_EARLYCON_MEM_BASE, paddr & PAGE_MASK);
+	base = (void __iomem *)__fix_to_virt(FIX_EARLYCON_MEM_BASE);
+	base += paddr & ~PAGE_MASK;
+#else
+	base = ioremap(paddr, size);
+#endif
+	if (!base)
+		pr_err("%s: Couldn't map %pa\n", __func__, &paddr);
+
+	return base;
+}
+
+static void __init earlycon_init(struct earlycon_device *device,
+				 const char *name)
+{
+	struct console *earlycon = device->con;
+	const char *s;
+	size_t len;
+
+	/* scan backwards from end of string for first non-numeral */
+	for (s = name + strlen(name);
+	     s > name && s[-1] >= '0' && s[-1] <= '9';
+	     s--)
+		;
+	if (*s)
+		earlycon->index = simple_strtoul(s, NULL, 10);
+	len = s - name;
+	strscpy(earlycon->name, name, min(len + 1, sizeof(earlycon->name)));
+	earlycon->data = &early_console_dev;
+}
+
+static void __init earlycon_print_info(struct earlycon_device *device)
+{
+	struct console *earlycon = device->con;
+	struct uart_port *port = &device->port;
+
+	if (port->iotype == UPIO_MEM || port->iotype == UPIO_MEM16 ||
+	    port->iotype == UPIO_MEM32 || port->iotype == UPIO_MEM32BE)
+		pr_info("%s%d at MMIO%s %pa (options '%s')\n",
+			earlycon->name, earlycon->index,
+			(port->iotype == UPIO_MEM) ? "" :
+			(port->iotype == UPIO_MEM16) ? "16" :
+			(port->iotype == UPIO_MEM32) ? "32" : "32be",
+			&port->mapbase, device->options);
+	else
+		pr_info("%s%d at I/O port 0x%lx (options '%s')\n",
+			earlycon->name, earlycon->index,
+			port->iobase, device->options);
+}
+
+static int __init parse_options(struct earlycon_device *device, char *options)
+{
+	struct uart_port *port = &device->port;
+	int length;
+	resource_size_t addr;
+
+	if (uart_parse_earlycon(options, &port->iotype, &addr, &options))
+		return -EINVAL;
+
+	switch (port->iotype) {
+	case UPIO_MEM:
+		port->mapbase = addr;
+		break;
+	case UPIO_MEM16:
+		port->regshift = 1;
+		port->mapbase = addr;
+		break;
+	case UPIO_MEM32:
+	case UPIO_MEM32BE:
+		port->regshift = 2;
+		port->mapbase = addr;
+		break;
+	case UPIO_PORT:
+		port->iobase = addr;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	if (options) {
+		char *uartclk;
+
+		device->baud = simple_strtoul(options, NULL, 0);
+		uartclk = strchr(options, ',');
+		if (uartclk && kstrtouint(uartclk + 1, 0, &port->uartclk) < 0)
+			pr_warn("[%s] unsupported earlycon uart clkrate option\n",
+				options);
+		length = min(strcspn(options, " ") + 1,
+			     (size_t)(sizeof(device->options)));
+		strscpy(device->options, options, length);
+	}
+
+	return 0;
+}
+
+static int __init register_earlycon(char *buf, const struct earlycon_id *match)
+{
+	int err;
+	struct uart_port *port = &early_console_dev.port;
+
+	/* On parsing error, pass the options buf to the setup function */
+	if (buf && !parse_options(&early_console_dev, buf))
+		buf = NULL;
+
+	spin_lock_init(&port->lock);
+	if (!port->uartclk)
+		port->uartclk = BASE_BAUD * 16;
+	if (port->mapbase)
+		port->membase = earlycon_map(port->mapbase, 64);
+
+	earlycon_init(&early_console_dev, match->name);
+	err = match->setup(&early_console_dev, buf);
+	earlycon_print_info(&early_console_dev);
+	if (err < 0)
+		return err;
+	if (!early_console_dev.con->write)
+		return -ENODEV;
+
+	register_console(early_console_dev.con);
+	return 0;
+}
+
+/**
+ *	setup_earlycon - match and register earlycon console
+ *	@buf:	earlycon param string
+ *
+ *	Registers the earlycon console matching the earlycon specified
+ *	in the param string @buf. Acceptable param strings are of the form
+ *	   <name>,io|mmio|mmio32|mmio32be,<addr>,<options>
+ *	   <name>,0x<addr>,<options>
+ *	   <name>,<options>
+ *	   <name>
+ *
+ *	Only for the third form does the earlycon setup() method receive the
+ *	<options> string in the 'options' parameter; all other forms set
+ *	the parameter to NULL.
+ *
+ *	Returns 0 if an attempt to register the earlycon was made,
+ *	otherwise negative error code
+ */
+int __init setup_earlycon(char *buf)
+{
+	const struct earlycon_id *match;
+	bool empty_compatible = true;
+
+	if (!buf || !buf[0])
+		return -EINVAL;
+
+	if (console_is_registered(&early_con))
+		return -EALREADY;
+
+again:
+	for (match = __earlycon_table; match < __earlycon_table_end; match++) {
+		size_t len = strlen(match->name);
+
+		if (strncmp(buf, match->name, len))
+			continue;
+
+		/* prefer entries with empty compatible */
+		if (empty_compatible && *match->compatible)
+			continue;
+
+		if (buf[len]) {
+			if (buf[len] != ',')
+				continue;
+			buf += len + 1;
+		} else
+			buf = NULL;
+
+		return register_earlycon(buf, match);
+	}
+
+	if (empty_compatible) {
+		empty_compatible = false;
+		goto again;
+	}
+
+	return -ENOENT;
+}
+
+/*
+ * This defers the initialization of the early console until after ACPI has
+ * been initialized.
+ */
+bool earlycon_acpi_spcr_enable __initdata;
+
+/* early_param wrapper for setup_earlycon() */
+static int __init param_setup_earlycon(char *buf)
+{
+	int err;
+
+	/* Just 'earlycon' is a valid param for devicetree and ACPI SPCR. */
+	if (!buf || !buf[0]) {
+		if (IS_ENABLED(CONFIG_ACPI_SPCR_TABLE)) {
+			earlycon_acpi_spcr_enable = true;
+			return 0;
+		} else if (!buf) {
+			return early_init_dt_scan_chosen_stdout();
+		}
+	}
+
+	err = setup_earlycon(buf);
+	if (err == -ENOENT || err == -EALREADY)
+		return 0;
+	return err;
+}
+early_param("earlycon", param_setup_earlycon);
+
+#ifdef CONFIG_OF_EARLY_FLATTREE
+
+int __init of_setup_earlycon(const struct earlycon_id *match,
+			     unsigned long node,
+			     const char *options)
+{
+	int err;
+	struct uart_port *port = &early_console_dev.port;
+	const __be32 *val;
+	bool big_endian;
+	u64 addr;
+
+	if (console_is_registered(&early_con))
+		return -EALREADY;
+
+	spin_lock_init(&port->lock);
+	port->iotype = UPIO_MEM;
+	addr = of_flat_dt_translate_address(node);
+	if (addr == OF_BAD_ADDR) {
+		pr_warn("[%s] bad address\n", match->name);
+		return -ENXIO;
+	}
+	port->mapbase = addr;
+
+	val = of_get_flat_dt_prop(node, "reg-offset", NULL);
+	if (val)
+		port->mapbase += be32_to_cpu(*val);
+	port->membase = earlycon_map(port->mapbase, SZ_4K);
+
+	val = of_get_flat_dt_prop(node, "reg-shift", NULL);
+	if (val)
+		port->regshift = be32_to_cpu(*val);
+	big_endian = of_get_flat_dt_prop(node, "big-endian", NULL) != NULL ||
+		(IS_ENABLED(CONFIG_CPU_BIG_ENDIAN) &&
+		 of_get_flat_dt_prop(node, "native-endian", NULL) != NULL);
+	val = of_get_flat_dt_prop(node, "reg-io-width", NULL);
+	if (val) {
+		switch (be32_to_cpu(*val)) {
+		case 1:
+			port->iotype = UPIO_MEM;
+			break;
+		case 2:
+			port->iotype = UPIO_MEM16;
+			break;
+		case 4:
+			port->iotype = (big_endian) ? UPIO_MEM32BE : UPIO_MEM32;
+			break;
+		default:
+			pr_warn("[%s] unsupported reg-io-width\n", match->name);
+			return -EINVAL;
+		}
+	}
+
+	val = of_get_flat_dt_prop(node, "current-speed", NULL);
+	if (val)
+		early_console_dev.baud = be32_to_cpu(*val);
+
+	val = of_get_flat_dt_prop(node, "clock-frequency", NULL);
+	if (val)
+		port->uartclk = be32_to_cpu(*val);
+
+	if (options) {
+		early_console_dev.baud = simple_strtoul(options, NULL, 0);
+		strscpy(early_console_dev.options, options,
+			sizeof(early_console_dev.options));
+	}
+	earlycon_init(&early_console_dev, match->name);
+	err = match->setup(&early_console_dev, options);
+	earlycon_print_info(&early_console_dev);
+	if (err < 0)
+		return err;
+	if (!early_console_dev.con->write)
+		return -ENODEV;
+
+
+	register_console(early_console_dev.con);
+	return 0;
+}
+
+#endif /* CONFIG_OF_EARLY_FLATTREE */