linux-kernel - [PATCH 1/2] thermal/drivers/core: Add init section table for self-encapsulation

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Date:   Wed, 12 Jun 2019 22:13:24 +0200
From:   Daniel Lezcano <daniel.lezcano@...aro.org>
To:     rui.zhang@...el.com
Cc:     linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
        amit.kucheria@...aro.org
Subject: [PATCH 1/2] thermal/drivers/core: Add init section table for self-encapsulation

Currently the governors are declared in their respective files but they
export their [un]register functions which in turn call the [un]register
governors core's functions. That implies a cyclic dependency which is
not desirable. There is a way to self-encapsulate the governors by letting
them to declare themselves in a __init section table.

Define the table in the asm generic linker description like the other
tables and provide the specific macros to deal with.

Reviewed-by: Amit Kucheria <amit.kucheria@...aro.org>
Signed-off-by: Daniel Lezcano <daniel.lezcano@...aro.org>
---
 drivers/thermal/thermal_core.h    | 15 +++++++++++++++
 include/asm-generic/vmlinux.lds.h | 11 +++++++++++
 2 files changed, 26 insertions(+)

diff --git a/drivers/thermal/thermal_core.h b/drivers/thermal/thermal_core.h
index 0df190ed82a7..be901e84aa65 100644
--- a/drivers/thermal/thermal_core.h
+++ b/drivers/thermal/thermal_core.h
@@ -15,6 +15,21 @@
 /* Initial state of a cooling device during binding */
 #define THERMAL_NO_TARGET -1UL
 
+/* Init section thermal table */
+extern struct thermal_governor *__governor_thermal_table[];
+extern struct thermal_governor *__governor_thermal_table_end[];
+
+#define THERMAL_TABLE_ENTRY(table, name)			\
+	(static typeof(name) *__thermal_table_entry_##name	\
+	__used __section(__##table##_thermal_table) = &name)
+
+#define THERMAL_GOVERNOR_DECLARE(name)	THERMAL_TABLE_ENTRY(governor, name)
+
+#define for_each_governor_table(__governor)		\
+	for (__governor = __governor_thermal_table;	\
+	     __governor < __governor_thermal_table_end;	\
+	     __governor++)
+
 /*
  * This structure is used to describe the behavior of
  * a certain cooling device on a certain trip point
diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index f8f6f04c4453..8312fdc2b2fa 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -239,6 +239,16 @@
 #define ACPI_PROBE_TABLE(name)
 #endif
 
+#ifdef CONFIG_THERMAL
+#define THERMAL_TABLE(name)						\
+	. = ALIGN(8);							\
+	__##name##_thermal_table = .;					\
+	KEEP(*(__##name##_thermal_table))				\
+	__##name##_thermal_table_end = .;
+#else
+#define THERMAL_TABLE(name)
+#endif
+
 #define KERNEL_DTB()							\
 	STRUCT_ALIGN();							\
 	__dtb_start = .;						\
@@ -609,6 +619,7 @@
 	IRQCHIP_OF_MATCH_TABLE()					\
 	ACPI_PROBE_TABLE(irqchip)					\
 	ACPI_PROBE_TABLE(timer)						\
+	THERMAL_TABLE(governor)						\
 	EARLYCON_TABLE()						\
 	LSM_TABLE()
 
-- 
2.17.1