[PATCH v2] serial: earlycon: rework common framework for earlycon declarations

From: Masahiro Yamada
Date: Fri Feb 12 2016 - 05:36:54 EST


Commit 71f50c6d9a22 ("of: drop symbols declared by _OF_DECLARE() from
modules") fixed the link error introduced by commit b8d20e06eaad
("serial: 8250_uniphier: add earlycon support").

After commit 2eaa790989e0 ("earlycon: Use common framework for
earlycon declarations") was applied, the link error came back
because the commit reworked OF_EARLYCON_DECLARE() to not use
_OF_DECLARE().

This commit reworks OF_EARLYCON_DECLARE() again based on
_OF_DECLARE(). My motivations are:

- Fix the link error in a generic way (without patching
drivers/tty/serial/8250/8250_uniphier.c)

- Delete struct earlycon_id. This struct is re-inventing the wheel;
the fields "name", "compatible", "setup" can be implemented in
struct of_device_id as other frameworks do.

The difference between OF_EARLYCON_DECLARE() and other users of
_OF_DECLARE is that OF_EARLYCON_DECLARE() needs to fill the "name"
field of struct of_device_id. To make it easier, a new macro
_OF_DECLARE_WITH_NAME() has been added. It fills the "name" field
with the given argument. On the other hand, _OF_DECLARE() sets it
to a null string; this is the same behavior as before.

Fixes: 2eaa790989e0 ("earlycon: Use common framework for earlycon declarations")
Signed-off-by: Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx>
---

I confirmed this patch can apply onto "next-20160212" tag of linux-next.

In order to apply it onto the "tty-next" branch of TTY subsytem,
Greg will have to pull v4.5-rc3 in.


Changes in v2:
Minor updates of git-log
- fix a typo framework/frameworks/).
- s/Grag/Greg/ (Sorry!)

drivers/of/fdt.c | 7 ++-----
drivers/tty/serial/earlycon.c | 19 +++++++++++++------
include/asm-generic/vmlinux.lds.h | 12 ++----------
include/linux/of.h | 22 +++++++++++++++-------
include/linux/serial_core.h | 23 +++++++----------------
5 files changed, 39 insertions(+), 44 deletions(-)

diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
index e2295b2..ad262e9 100644
--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c
@@ -802,7 +802,7 @@ static int __init early_init_dt_scan_chosen_serial(void)
int offset;
const char *p, *q, *options = NULL;
int l;
- const struct earlycon_id *match;
+ const struct of_device_id *match;
const void *fdt = initial_boot_params;

offset = fdt_path_offset(fdt, "/chosen");
@@ -829,10 +829,7 @@ static int __init early_init_dt_scan_chosen_serial(void)
return 0;
}

- for (match = __earlycon_table; match < __earlycon_table_end; match++) {
- if (!match->compatible[0])
- continue;
-
+ for (match = __earlycon_of_table; match->compatible[0]; match++) {
if (fdt_node_check_compatible(fdt, offset, match->compatible))
continue;

diff --git a/drivers/tty/serial/earlycon.c b/drivers/tty/serial/earlycon.c
index 067783f..4888ced 100644
--- a/drivers/tty/serial/earlycon.c
+++ b/drivers/tty/serial/earlycon.c
@@ -38,6 +38,9 @@ static struct earlycon_device early_console_dev = {
.con = &early_con,
};

+static const struct of_device_id __earlycon_of_table_sentinel
+ __used __section(__earlycon_of_table_end);
+
static void __iomem * __init earlycon_map(unsigned long paddr, size_t size)
{
void __iomem *base;
@@ -127,9 +130,10 @@ static int __init parse_options(struct earlycon_device *device, char *options)
return 0;
}

-static int __init register_earlycon(char *buf, const struct earlycon_id *match)
+static int __init register_earlycon(char *buf, const struct of_device_id *match)
{
int err;
+ int (*setup)(struct earlycon_device *, const char *options);
struct uart_port *port = &early_console_dev.port;

/* On parsing error, pass the options buf to the setup function */
@@ -142,7 +146,8 @@ static int __init register_earlycon(char *buf, const struct earlycon_id *match)
port->membase = earlycon_map(port->mapbase, 64);

earlycon_init(&early_console_dev, match->name);
- err = match->setup(&early_console_dev, buf);
+ setup = match->data;
+ err = setup(&early_console_dev, buf);
if (err < 0)
return err;
if (!early_console_dev.con->write)
@@ -172,7 +177,7 @@ static int __init register_earlycon(char *buf, const struct earlycon_id *match)
*/
int __init setup_earlycon(char *buf)
{
- const struct earlycon_id *match;
+ const struct of_device_id *match;

if (!buf || !buf[0])
return -EINVAL;
@@ -180,7 +185,7 @@ int __init setup_earlycon(char *buf)
if (early_con.flags & CON_ENABLED)
return -EALREADY;

- for (match = __earlycon_table; match < __earlycon_table_end; match++) {
+ for (match = __earlycon_of_table; match->name[0]; match++) {
size_t len = strlen(match->name);

if (strncmp(buf, match->name, len))
@@ -220,12 +225,13 @@ early_param("earlycon", param_setup_earlycon);

#ifdef CONFIG_OF_EARLY_FLATTREE

-int __init of_setup_earlycon(const struct earlycon_id *match,
+int __init of_setup_earlycon(const struct of_device_id *match,
unsigned long node,
const char *options)
{
int err;
struct uart_port *port = &early_console_dev.port;
+ int (*setup)(struct earlycon_device *, const char *options);
const __be32 *val;
bool big_endian;
u64 addr;
@@ -273,7 +279,8 @@ int __init of_setup_earlycon(const struct earlycon_id *match,
sizeof(early_console_dev.options));
}
earlycon_init(&early_console_dev, match->name);
- err = match->setup(&early_console_dev, options);
+ setup = match->data;
+ err = setup(&early_console_dev, options);
if (err < 0)
return err;
if (!early_console_dev.con->write)
diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index e9a81a6..699f4a5 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -153,15 +153,6 @@
#define TRACE_SYSCALLS()
#endif

-#ifdef CONFIG_SERIAL_EARLYCON
-#define EARLYCON_TABLE() STRUCT_ALIGN(); \
- VMLINUX_SYMBOL(__earlycon_table) = .; \
- *(__earlycon_table) \
- VMLINUX_SYMBOL(__earlycon_table_end) = .;
-#else
-#define EARLYCON_TABLE()
-#endif
-
#define ___OF_TABLE(cfg, name) _OF_TABLE_##cfg(name)
#define __OF_TABLE(cfg, name) ___OF_TABLE(cfg, name)
#define OF_TABLE(cfg, name) __OF_TABLE(config_enabled(cfg), name)
@@ -179,6 +170,7 @@
#define RESERVEDMEM_OF_TABLES() OF_TABLE(CONFIG_OF_RESERVED_MEM, reservedmem)
#define CPU_METHOD_OF_TABLES() OF_TABLE(CONFIG_SMP, cpu_method)
#define CPUIDLE_METHOD_OF_TABLES() OF_TABLE(CONFIG_CPU_IDLE, cpuidle_method)
+#define EARLYCON_OF_TABLES() OF_TABLE(CONFIG_SERIAL_EARLYCON, earlycon)

#ifdef CONFIG_ACPI
#define ACPI_PROBE_TABLE(name) \
@@ -525,7 +517,7 @@
IRQCHIP_OF_MATCH_TABLE() \
ACPI_PROBE_TABLE(irqchip) \
ACPI_PROBE_TABLE(clksrc) \
- EARLYCON_TABLE()
+ EARLYCON_OF_TABLES()

#define INIT_TEXT \
*(.init.text) \
diff --git a/include/linux/of.h b/include/linux/of.h
index dc6e396..6e57245 100644
--- a/include/linux/of.h
+++ b/include/linux/of.h
@@ -930,19 +930,27 @@ static inline int of_get_available_child_count(const struct device_node *np)
}

#if defined(CONFIG_OF) && !defined(MODULE)
-#define _OF_DECLARE(table, name, compat, fn, fn_type) \
- static const struct of_device_id __of_table_##name \
+#define __OF_DECLARE(table, name1, name2, compat, fn, fn_type) \
+ static const struct of_device_id __UNIQUE_ID(__of_table_##name1)\
__used __section(__##table##_of_table) \
- = { .compatible = compat, \
+ = { .name = name2, \
+ .compatible = compat, \
.data = (fn == (fn_type)NULL) ? fn : fn }
#else
-#define _OF_DECLARE(table, name, compat, fn, fn_type) \
- static const struct of_device_id __of_table_##name \
+#define __OF_DECLARE(table, name1, name2, compat, fn, fn_type) \
+ static const struct of_device_id __UNIQUE_ID(__of_table_##name1)\
__attribute__((unused)) \
- = { .compatible = compat, \
- .data = (fn == (fn_type)NULL) ? fn : fn }
+ = { .name = name2, \
+ .compatible = compat, \
+ .data = (fn == (fn_type)NULL) ? fn : fn }
#endif

+#define _OF_DECLARE(table, name, compat, fn, fn_type) \
+ __OF_DECLARE(table, name, "", compat, fn, fn_type)
+
+#define _OF_DECLARE_WITH_NAME(table, name, compat, fn, fn_type) \
+ __OF_DECLARE(table, name, __stringify(name), compat, fn, fn_type)
+
typedef int (*of_init_fn_2)(struct device_node *, struct device_node *);
typedef void (*of_init_fn_1)(struct device_node *);

diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
index cbfcf38..0f13160 100644
--- a/include/linux/serial_core.h
+++ b/include/linux/serial_core.h
@@ -24,6 +24,7 @@
#include <linux/compiler.h>
#include <linux/interrupt.h>
#include <linux/circ_buf.h>
+#include <linux/mod_devicetable.h>
#include <linux/spinlock.h>
#include <linux/sched.h>
#include <linux/tty.h>
@@ -340,26 +341,16 @@ struct earlycon_device {
unsigned int baud;
};

-struct earlycon_id {
- char name[16];
- char compatible[128];
- int (*setup)(struct earlycon_device *, const char *options);
-} __aligned(32);
+extern const struct of_device_id __earlycon_of_table[];

-extern const struct earlycon_id __earlycon_table[];
-extern const struct earlycon_id __earlycon_table_end[];
+#define OF_EARLYCON_DECLARE(name, compat, fn) \
+ _OF_DECLARE_WITH_NAME(earlycon, name, compat, fn, void *)

-#define OF_EARLYCON_DECLARE(_name, compat, fn) \
- static const struct earlycon_id __UNIQUE_ID(__earlycon_##_name) \
- __used __section(__earlycon_table) \
- = { .name = __stringify(_name), \
- .compatible = compat, \
- .setup = fn }
-
-#define EARLYCON_DECLARE(_name, fn) OF_EARLYCON_DECLARE(_name, "", fn)
+#define EARLYCON_DECLARE(_name, fn) \
+ OF_EARLYCON_DECLARE(_name, "-earlycon-dummy-compat-string-", fn)

extern int setup_earlycon(char *buf);
-extern int of_setup_earlycon(const struct earlycon_id *match,
+extern int of_setup_earlycon(const struct of_device_id *match,
unsigned long node,
const char *options);

--
1.9.1