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[PATCH v5 00/11] Earlycon cleanup

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  [PATCH v5 00/11] Earlycon cleanup Peter Hurley <peter@hurleysoftware.com> - 2016-01-16 22:40 +0100
    [PATCH v5 11/11] serial: 8250_omap: Add omap8250 earlycon Peter Hurley <peter@hurleysoftware.com> - 2016-01-16 22:40 +0100
    [PATCH v5 06/11] of: earlycon: Move address translation to of_setup_earlycon() Peter Hurley <peter@hurleysoftware.com> - 2016-01-16 22:40 +0100
      Re: [PATCH v5 06/11] of: earlycon: Move address translation to  of_setup_earlycon() kbuild test robot <lkp@intel.com> - 2016-01-16 23:10 +0100
    [PATCH v5 07/11] serial: earlycon: Common log banner for command line and DT Peter Hurley <peter@hurleysoftware.com> - 2016-01-16 22:40 +0100
    [PATCH v5 01/11] earlycon: Use common framework for earlycon declarations Peter Hurley <peter@hurleysoftware.com> - 2016-01-16 22:50 +0100
    [PATCH v5 05/11] of: earlycon: Initialize port fields from DT properties Peter Hurley <peter@hurleysoftware.com> - 2016-01-16 22:50 +0100
      Re: [PATCH v5 05/11] of: earlycon: Initialize port fields from DT  properties kbuild test robot <lkp@intel.com> - 2016-01-16 23:00 +0100
    [PATCH v5 02/11] serial: earlycon: Fixup earlycon console name and index Peter Hurley <peter@hurleysoftware.com> - 2016-01-16 22:50 +0100
    [PATCH v5 03/11] of: earlycon: Fixup earlycon console name and index Peter Hurley <peter@hurleysoftware.com> - 2016-01-16 22:50 +0100
    [PATCH v5 04/11] of: earlycon: Add options string handling Peter Hurley <peter@hurleysoftware.com> - 2016-01-16 22:50 +0100
    [PATCH v5 09/11] serial: 8250_early: Use port->regshift Peter Hurley <peter@hurleysoftware.com> - 2016-01-16 22:50 +0100
    [PATCH v5 08/11] serial: earlycon: Show the earlycon "driver" in banner Peter Hurley <peter@hurleysoftware.com> - 2016-01-16 22:50 +0100
    [PATCH v5 10/11] of: earlycon: Log more helpful message if stdout-path node not found Peter Hurley <peter@hurleysoftware.com> - 2016-01-16 22:50 +0100
    [PATCH v6 11/12] of: earlycon: Log more helpful message if stdout-path node not found Peter Hurley <peter@hurleysoftware.com> - 2016-01-17 00:30 +0100
    [PATCH v6 05/12] of: earlycon: Add options string handling Peter Hurley <peter@hurleysoftware.com> - 2016-01-17 00:30 +0100
    [PATCH v6 04/12] of: earlycon: Fixup earlycon console name and index Peter Hurley <peter@hurleysoftware.com> - 2016-01-17 00:30 +0100
    [PATCH v6 09/12] serial: earlycon: Show the earlycon "driver" in banner Peter Hurley <peter@hurleysoftware.com> - 2016-01-17 00:30 +0100
    [PATCH v6 00/12] Earlycon cleanup Peter Hurley <peter@hurleysoftware.com> - 2016-01-17 00:30 +0100
      [PATCH v6 02/12] earlycon: Use common framework for earlycon declarations Peter Hurley <peter@hurleysoftware.com> - 2016-01-17 00:30 +0100
      [PATCH v6 10/12] serial: 8250_early: Use port->regshift Peter Hurley <peter@hurleysoftware.com> - 2016-01-17 00:30 +0100
      [PATCH v6 07/12] of: earlycon: Move address translation to of_setup_earlycon() Peter Hurley <peter@hurleysoftware.com> - 2016-01-17 00:30 +0100
      [PATCH v6 01/12] of: earlycon: of_setup_earlycon() requires CONFIG_OF_EARLY_FLATTREE Peter Hurley <peter@hurleysoftware.com> - 2016-01-17 00:30 +0100
      [PATCH v6 03/12] serial: earlycon: Fixup earlycon console name and index Peter Hurley <peter@hurleysoftware.com> - 2016-01-17 00:30 +0100
      [PATCH v6 08/12] serial: earlycon: Common log banner for command line and DT Peter Hurley <peter@hurleysoftware.com> - 2016-01-17 00:30 +0100
      [PATCH v6 06/12] of: earlycon: Initialize port fields from DT properties Peter Hurley <peter@hurleysoftware.com> - 2016-01-17 00:30 +0100
      [PATCH v6 12/12] serial: 8250_omap: Add omap8250 earlycon Peter Hurley <peter@hurleysoftware.com> - 2016-01-17 00:30 +0100

Page 2 of 2 — ← Prev page 1 [2]

#1311078 — [PATCH v6 10/12] serial: 8250_early: Use port->regshift

earlycon initializes struct uart_port::regshift to the correct
value for UPIO_MEM32 already. Use the port field rather than
hard-coded value.

This enables broader support for various i/o access methods in
8250 earlycon (eg., omap8250 earlycon).

Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
---
 drivers/tty/serial/8250/8250_early.c | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/drivers/tty/serial/8250/8250_early.c b/drivers/tty/serial/8250/8250_early.c
index af62131..180143c 100644
--- a/drivers/tty/serial/8250/8250_early.c
+++ b/drivers/tty/serial/8250/8250_early.c
@@ -39,15 +39,17 @@
 
 static unsigned int __init serial8250_early_in(struct uart_port *port, int offset)
 {
+	offset <<= port->regshift;
+
 	switch (port->iotype) {
 	case UPIO_MEM:
 		return readb(port->membase + offset);
 	case UPIO_MEM16:
-		return readw(port->membase + (offset << 1));
+		return readw(port->membase + offset);
 	case UPIO_MEM32:
-		return readl(port->membase + (offset << 2));
+		return readl(port->membase + offset);
 	case UPIO_MEM32BE:
-		return ioread32be(port->membase + (offset << 2));
+		return ioread32be(port->membase + offset);
 	case UPIO_PORT:
 		return inb(port->iobase + offset);
 	default:
@@ -57,18 +59,20 @@ static unsigned int __init serial8250_early_in(struct uart_port *port, int offse
 
 static void __init serial8250_early_out(struct uart_port *port, int offset, int value)
 {
+	offset <<= port->regshift;
+
 	switch (port->iotype) {
 	case UPIO_MEM:
 		writeb(value, port->membase + offset);
 		break;
 	case UPIO_MEM16:
-		writew(value, port->membase + (offset << 1));
+		writew(value, port->membase + offset);
 		break;
 	case UPIO_MEM32:
-		writel(value, port->membase + (offset << 2));
+		writel(value, port->membase + offset);
 		break;
 	case UPIO_MEM32BE:
-		iowrite32be(value, port->membase + (offset << 2));
+		iowrite32be(value, port->membase + offset);
 		break;
 	case UPIO_PORT:
 		outb(value, port->iobase + offset);
-- 
2.7.0

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#1311079 — [PATCH v6 07/12] of: earlycon: Move address translation to of_setup_earlycon()

Cleanup the early DT/earlycon separation; remove the 'addr' parameter
from of_setup_earlycon() and get the uart phys addr directly with a
new wrapper function, of_flat_dt_translate_addr(). Limit
fdt_translate_address() to file scope.

Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
---
 drivers/of/fdt.c              |  8 +-------
 drivers/of/fdt_address.c      | 11 ++++++++++-
 drivers/tty/serial/earlycon.c | 12 +++++++++---
 include/linux/of_fdt.h        |  2 +-
 include/linux/serial_core.h   |  2 +-
 5 files changed, 22 insertions(+), 13 deletions(-)

diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
index e8fd54a..918809e 100644
--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c
@@ -827,19 +827,13 @@ static int __init early_init_dt_scan_chosen_serial(void)
 		return -ENODEV;
 
 	for (match = __earlycon_table; match < __earlycon_table_end; match++) {
-		u64 addr;
-
 		if (!match->compatible[0])
 			continue;
 
 		if (fdt_node_check_compatible(fdt, offset, match->compatible))
 			continue;
 
-		addr = fdt_translate_address(fdt, offset);
-		if (addr == OF_BAD_ADDR)
-			return -ENXIO;
-
-		of_setup_earlycon(addr, match, offset, options);
+		of_setup_earlycon(match, offset, options);
 		return 0;
 	}
 	return -ENODEV;
diff --git a/drivers/of/fdt_address.c b/drivers/of/fdt_address.c
index 8d3dc6f..dca8f9b 100644
--- a/drivers/of/fdt_address.c
+++ b/drivers/of/fdt_address.c
@@ -161,7 +161,7 @@ static int __init fdt_translate_one(const void *blob, int parent,
  * that can be mapped to a cpu physical address). This is not really specified
  * that way, but this is traditionally the way IBM at least do things
  */
-u64 __init fdt_translate_address(const void *blob, int node_offset)
+static u64 __init fdt_translate_address(const void *blob, int node_offset)
 {
 	int parent, len;
 	const struct of_bus *bus, *pbus;
@@ -239,3 +239,12 @@ u64 __init fdt_translate_address(const void *blob, int node_offset)
  bail:
 	return result;
 }
+
+/**
+ * of_flat_dt_translate_address - translate DT addr into CPU phys addr
+ * @node: node in the flat blob
+ */
+u64 __init of_flat_dt_translate_address(unsigned long node)
+{
+	return fdt_translate_address(initial_boot_params, node);
+}
diff --git a/drivers/tty/serial/earlycon.c b/drivers/tty/serial/earlycon.c
index 7089667..baee9ad 100644
--- a/drivers/tty/serial/earlycon.c
+++ b/drivers/tty/serial/earlycon.c
@@ -19,6 +19,7 @@
 #include <linux/io.h>
 #include <linux/serial_core.h>
 #include <linux/sizes.h>
+#include <linux/of.h>
 #include <linux/of_fdt.h>
 
 #ifdef CONFIG_FIX_EARLYCON_MEM
@@ -218,8 +219,7 @@ early_param("earlycon", param_setup_earlycon);
 
 #ifdef CONFIG_OF_EARLY_FLATTREE
 
-int __init of_setup_earlycon(unsigned long addr,
-			     const struct earlycon_id *match,
+int __init of_setup_earlycon(const struct earlycon_id *match,
 			     unsigned long node,
 			     const char *options)
 {
@@ -227,12 +227,18 @@ int __init of_setup_earlycon(unsigned long addr,
 	struct uart_port *port = &early_console_dev.port;
 	const __be32 *val;
 	bool big_endian;
+	u64 addr;
 
 	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;
 	port->uartclk = BASE_BAUD * 16;
-	port->membase = earlycon_map(addr, SZ_4K);
+	port->membase = earlycon_map(port->mapbase, SZ_4K);
 
 	val = of_get_flat_dt_prop(node, "reg-offset", NULL);
 	if (val)
diff --git a/include/linux/of_fdt.h b/include/linux/of_fdt.h
index df9ef38..2fbe868 100644
--- a/include/linux/of_fdt.h
+++ b/include/linux/of_fdt.h
@@ -88,7 +88,7 @@ extern void unflatten_device_tree(void);
 extern void unflatten_and_copy_device_tree(void);
 extern void early_init_devtree(void *);
 extern void early_get_first_memblock_info(void *, phys_addr_t *);
-extern u64 fdt_translate_address(const void *blob, int node_offset);
+extern u64 of_flat_dt_translate_address(unsigned long node);
 extern void of_fdt_limit_memory(int limit);
 #else /* CONFIG_OF_FLATTREE */
 static inline void early_init_fdt_scan_reserved_mem(void) {}
diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
index 6d1bed8..cbfcf38 100644
--- a/include/linux/serial_core.h
+++ b/include/linux/serial_core.h
@@ -359,7 +359,7 @@ extern const struct earlycon_id __earlycon_table_end[];
 #define EARLYCON_DECLARE(_name, fn)	OF_EARLYCON_DECLARE(_name, "", fn)
 
 extern int setup_earlycon(char *buf);
-extern int of_setup_earlycon(unsigned long addr, const struct earlycon_id *match,
+extern int of_setup_earlycon(const struct earlycon_id *match,
 			     unsigned long node,
 			     const char *options);
 
-- 
2.7.0

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#1311080 — [PATCH v6 01/12] of: earlycon: of_setup_earlycon() requires CONFIG_OF_EARLY_FLATTREE

DT earlycon is only supported for CONFIG_OF_EARLY_FLATTREE=y; exclude
of_setup_earlycon() if not defined.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
---
 drivers/tty/serial/earlycon.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/tty/serial/earlycon.c b/drivers/tty/serial/earlycon.c
index 3f24236..54419a2 100644
--- a/drivers/tty/serial/earlycon.c
+++ b/drivers/tty/serial/earlycon.c
@@ -204,6 +204,8 @@ static int __init param_setup_earlycon(char *buf)
 }
 early_param("earlycon", param_setup_earlycon);
 
+#ifdef CONFIG_OF_EARLY_FLATTREE
+
 int __init of_setup_earlycon(unsigned long addr,
 			     int (*setup)(struct earlycon_device *, const char *))
 {
@@ -227,3 +229,5 @@ int __init of_setup_earlycon(unsigned long addr,
 	register_console(early_console_dev.con);
 	return 0;
 }
+
+#endif /* CONFIG_OF_EARLY_FLATTREE */
-- 
2.7.0

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#1311081 — [PATCH v6 03/12] serial: earlycon: Fixup earlycon console name and index

Properly initialize the struct console 'name' and 'index' fields for
the registering earlycon. For earlycons w/o trailing numerals, the
index is set to 0; otherwise, the index is set to the value of the
trailing numeral. For example, the 'exynos4210' earlycon name == "exynos"
and index == 4210. Earlycons with embedded numerals will have all
non-trailing numerals as part of the name; for example, the 's3c2412'
earlycon name == "s3c" and index == 2412.

This ackward scheme was initially added for the uart8250 earlycon;
adopt this scheme for the other earlycon "drivers".

Introduce earlycon_init() which performs the string scanning and
initializes the name and index fields; encapsulate the other console
field initializations within.

Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
---
 drivers/tty/serial/earlycon.c | 25 ++++++++++++++++++++++---
 1 file changed, 22 insertions(+), 3 deletions(-)

diff --git a/drivers/tty/serial/earlycon.c b/drivers/tty/serial/earlycon.c
index d50b700..90b064f 100644
--- a/drivers/tty/serial/earlycon.c
+++ b/drivers/tty/serial/earlycon.c
@@ -27,9 +27,9 @@
 #include <asm/serial.h>
 
 static struct console early_con = {
-	.name =		"uart", /* 8250 console switch requires this name */
+	.name =		"uart",		/* fixed up at earlycon registration */
 	.flags =	CON_PRINTBUFFER | CON_BOOT,
-	.index =	-1,
+	.index =	0,
 };
 
 static struct earlycon_device early_console_dev = {
@@ -53,6 +53,25 @@ static void __iomem * __init earlycon_map(unsigned long paddr, size_t size)
 	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;
+	strlcpy(earlycon->name, name, min(len + 1, sizeof(earlycon->name)));
+	earlycon->data = &early_console_dev;
+}
+
 static int __init parse_options(struct earlycon_device *device, char *options)
 {
 	struct uart_port *port = &device->port;
@@ -119,7 +138,7 @@ static int __init register_earlycon(char *buf, const struct earlycon_id *match)
 	if (port->mapbase)
 		port->membase = earlycon_map(port->mapbase, 64);
 
-	early_console_dev.con->data = &early_console_dev;
+	earlycon_init(&early_console_dev, match->name);
 	err = match->setup(&early_console_dev, buf);
 	if (err < 0)
 		return err;
-- 
2.7.0

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#1311082 — [PATCH v6 08/12] serial: earlycon: Common log banner for command line and DT

Refactor the command line earlycon banner into earlycon_init() so
both earlycon startup methods output an info banner.

Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
---
 drivers/tty/serial/earlycon.c | 27 ++++++++++++++-------------
 1 file changed, 14 insertions(+), 13 deletions(-)

diff --git a/drivers/tty/serial/earlycon.c b/drivers/tty/serial/earlycon.c
index baee9ad..36b79f1 100644
--- a/drivers/tty/serial/earlycon.c
+++ b/drivers/tty/serial/earlycon.c
@@ -59,6 +59,7 @@ static void __init earlycon_init(struct earlycon_device *device,
 				 const char *name)
 {
 	struct console *earlycon = device->con;
+	struct uart_port *port = &device->port;
 	const char *s;
 	size_t len;
 
@@ -72,6 +73,19 @@ static void __init earlycon_init(struct earlycon_device *device,
 	len = s - name;
 	strlcpy(earlycon->name, name, min(len + 1, sizeof(earlycon->name)));
 	earlycon->data = &early_console_dev;
+
+	if (port->iotype == UPIO_MEM || port->iotype == UPIO_MEM16 ||
+	    port->iotype == UPIO_MEM32 || port->iotype == UPIO_MEM32BE)
+		pr_info("Early serial console at MMIO%s 0x%llx (options '%s')\n",
+			(port->iotype == UPIO_MEM) ? "" :
+			(port->iotype == UPIO_MEM16) ? "16" :
+			(port->iotype == UPIO_MEM32) ? "32" : "32be",
+			(unsigned long long)port->mapbase,
+			device->options);
+	else
+		pr_info("Early serial console at I/O port 0x%lx (options '%s')\n",
+			port->iobase,
+			device->options);
 }
 
 static int __init parse_options(struct earlycon_device *device, char *options)
@@ -110,19 +124,6 @@ static int __init parse_options(struct earlycon_device *device, char *options)
 		strlcpy(device->options, options, length);
 	}
 
-	if (port->iotype == UPIO_MEM || port->iotype == UPIO_MEM16 ||
-	    port->iotype == UPIO_MEM32 || port->iotype == UPIO_MEM32BE)
-		pr_info("Early serial console at MMIO%s 0x%llx (options '%s')\n",
-			(port->iotype == UPIO_MEM) ? "" :
-			(port->iotype == UPIO_MEM16) ? "16" :
-			(port->iotype == UPIO_MEM32) ? "32" : "32be",
-			(unsigned long long)port->mapbase,
-			device->options);
-	else
-		pr_info("Early serial console at I/O port 0x%lx (options '%s')\n",
-			port->iobase,
-			device->options);
-
 	return 0;
 }
 
-- 
2.7.0

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#1311083 — [PATCH v6 06/12] of: earlycon: Initialize port fields from DT properties

Read the optional "reg-offset", "reg-shift", "reg-io-width" and endianness
properties and initialize the respective struct uart_port field if found.

NB: These bindings are common to several drivers and the values merely
indicate the default value; the registering earlycon setup() method can
simply override the values if required.

Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
---
 drivers/of/fdt.c              |  2 +-
 drivers/tty/serial/earlycon.c | 31 +++++++++++++++++++++++++++++++
 include/linux/serial_core.h   |  1 +
 3 files changed, 33 insertions(+), 1 deletion(-)

diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
index cfd3b35..e8fd54a 100644
--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c
@@ -839,7 +839,7 @@ static int __init early_init_dt_scan_chosen_serial(void)
 		if (addr == OF_BAD_ADDR)
 			return -ENXIO;
 
-		of_setup_earlycon(addr, match, options);
+		of_setup_earlycon(addr, match, offset, options);
 		return 0;
 	}
 	return -ENODEV;
diff --git a/drivers/tty/serial/earlycon.c b/drivers/tty/serial/earlycon.c
index 7509ee34d..7089667 100644
--- a/drivers/tty/serial/earlycon.c
+++ b/drivers/tty/serial/earlycon.c
@@ -19,6 +19,7 @@
 #include <linux/io.h>
 #include <linux/serial_core.h>
 #include <linux/sizes.h>
+#include <linux/of_fdt.h>
 
 #ifdef CONFIG_FIX_EARLYCON_MEM
 #include <asm/fixmap.h>
@@ -219,10 +220,13 @@ early_param("earlycon", param_setup_earlycon);
 
 int __init of_setup_earlycon(unsigned long addr,
 			     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;
 
 	spin_lock_init(&port->lock);
 	port->iotype = UPIO_MEM;
@@ -230,6 +234,33 @@ int __init of_setup_earlycon(unsigned long addr,
 	port->uartclk = BASE_BAUD * 16;
 	port->membase = earlycon_map(addr, SZ_4K);
 
+	val = of_get_flat_dt_prop(node, "reg-offset", NULL);
+	if (val)
+		port->mapbase += be32_to_cpu(*val);
+	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;
+		}
+	}
+
 	if (options) {
 		strlcpy(early_console_dev.options, options,
 			sizeof(early_console_dev.options));
diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
index 62a4df0..6d1bed8 100644
--- a/include/linux/serial_core.h
+++ b/include/linux/serial_core.h
@@ -360,6 +360,7 @@ extern const struct earlycon_id __earlycon_table_end[];
 
 extern int setup_earlycon(char *buf);
 extern int of_setup_earlycon(unsigned long addr, const struct earlycon_id *match,
+			     unsigned long node,
 			     const char *options);
 
 struct uart_port *uart_get_console(struct uart_port *ports, int nr,
-- 
2.7.0

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#1311084 — [PATCH v6 12/12] serial: 8250_omap: Add omap8250 earlycon

Add DT earlycon for 8250_omap driver. This boot console is included
for kernels built with CONFIG_SERIAL_EARLYCON=y, CONFIG_OF=y,
CONFIG_SERIAL_8250_OMAP=y, and CONFIG_OF_EARLY_FLATTREE=y.

This boot console is enabled with the command line option "earlycon"
(without "=<name>...") when the DT 'stdout-path' property matches a
compatible uart. For example,

/ {
   chosen {
        stdout-path = "serial0:115200";
   };

   ....

   aliases {
        serial0 = &uart0;
   };

   ....

   ocp : ocp {
        uart0 : serial@44e09000 {
             compatible = "ti,omap3-uart";
        }
   };
};

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
---
 drivers/tty/serial/8250/8250_early.c | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/drivers/tty/serial/8250/8250_early.c b/drivers/tty/serial/8250/8250_early.c
index 180143c..3b3dbdc 100644
--- a/drivers/tty/serial/8250/8250_early.c
+++ b/drivers/tty/serial/8250/8250_early.c
@@ -149,3 +149,24 @@ EARLYCON_DECLARE(uart8250, early_serial8250_setup);
 EARLYCON_DECLARE(uart, early_serial8250_setup);
 OF_EARLYCON_DECLARE(ns16550, "ns16550", early_serial8250_setup);
 OF_EARLYCON_DECLARE(ns16550a, "ns16550a", early_serial8250_setup);
+
+#ifdef CONFIG_SERIAL_8250_OMAP
+
+static int __init early_omap8250_setup(struct earlycon_device *device,
+				       const char *options)
+{
+	struct uart_port *port = &device->port;
+
+	if (!(device->port.membase || device->port.iobase))
+		return -ENODEV;
+
+	port->regshift = 2;
+	device->con->write = early_serial8250_write;
+	return 0;
+}
+
+OF_EARLYCON_DECLARE(omap8250, "ti,omap2-uart", early_omap8250_setup);
+OF_EARLYCON_DECLARE(omap8250, "ti,omap3-uart", early_omap8250_setup);
+OF_EARLYCON_DECLARE(omap8250, "ti,omap4-uart", early_omap8250_setup);
+
+#endif
-- 
2.7.0

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