linux-kernel - [PATCH v2] clk: Provide notifier stubs when !COMMON

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Date:	Tue, 28 Jun 2016 13:25:04 +0200
From:	Krzysztof Kozlowski <k.kozlowski@...sung.com>
To:	Russell King <linux@...linux.org.uk>, linux-clk@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Michael Turquette <mturquette@...libre.com>,
	Stephen Boyd <sboyd@...eaurora.org>,
	MyungJoo Ham <myungjoo.ham@...sung.com>,
	Kyungmin Park <kyungmin.park@...sung.com>,
	linux-pm@...r.kernel.org
Cc:	Krzysztof Kozlowski <k.kozlowski@...sung.com>,
	Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>
Subject: [PATCH v2] clk: Provide notifier stubs when !COMMON_CLK

The clk notifier symbols are hidden by COMMON_CLK.  However on some
platforms HAVE_CLK might be set while COMMON_CLK not which leads to
compile test build errors like:

$ make.cross ARCH=sh
   drivers/devfreq/tegra-devfreq.c: In function 'tegra_actmon_rate_notify_cb':
>> drivers/devfreq/tegra-devfreq.c:391:16: error: 'POST_RATE_CHANGE' undeclared (first use in this function)
     if (action != POST_RATE_CHANGE)
                   ^
   drivers/devfreq/tegra-devfreq.c: In function 'tegra_devfreq_probe':
>> drivers/devfreq/tegra-devfreq.c:654:8: error: implicit declaration of function 'clk_notifier_register' [-Werror=implicit-function-declaration]
     err = clk_notifier_register(tegra->emc_clock, &tegra->rate_change_nb);
           ^

Export the macros and data type declarations outside of COMMON_CLK ifdef
and provide stubs to fix the compile testing.

Reported-by: kbuild test robot <lkp@...el.com>
Signed-off-by: Krzysztof Kozlowski <k.kozlowski@...sung.com>

---

Reported when testing patch [1] on ARCH=sh. I don't have the sh cross
compile toolchain so I cannot verify whether this fixes reported issue.
Tested on similar configuration on MIPS (HAVE_CLK && !COMMON_CLK)

[1] http://www.gossamer-threads.com/lists/linux/kernel/2471798

Changes since v1:
1. The struct clk_notifier_data also has to be visible.
---
 include/linux/clk.h | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/include/linux/clk.h b/include/linux/clk.h
index 834179f3fa72..123c02788807 100644
--- a/include/linux/clk.h
+++ b/include/linux/clk.h
@@ -20,8 +20,6 @@ struct device;
 
 struct clk;
 
-#ifdef CONFIG_COMMON_CLK
-
 /**
  * DOC: clk notifier callback types
  *
@@ -78,6 +76,8 @@ struct clk_notifier_data {
 	unsigned long		new_rate;
 };
 
+#ifdef CONFIG_COMMON_CLK
+
 /**
  * clk_notifier_register: register a clock rate-change notifier callback
  * @clk: clock whose rate we are interested in
@@ -140,6 +140,18 @@ bool clk_is_match(const struct clk *p, const struct clk *q);
 
 #else
 
+static inline int clk_notifier_register(struct clk *clk,
+					struct notifier_block *nb)
+{
+	return -ENOTSUPP;
+}
+
+static inline int clk_notifier_unregister(struct clk *clk,
+					  struct notifier_block *nb)
+{
+	return -ENOTSUPP;
+}
+
 static inline long clk_get_accuracy(struct clk *clk)
 {
 	return -ENOTSUPP;
-- 
1.9.1