linux-kernel - [PATCH] cpufreq: acpi: Allow new dynamics attributes to be added to acpi_cpufreq

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Date:	Thu,  3 Mar 2016 11:10:05 +0530
From:	Viresh Kumar <viresh.kumar@...aro.org>
To:	Rafael Wysocki <rjw@...ysocki.net>,
	srinivas.pandruvada@...ux.intel.com,
	Viresh Kumar <viresh.kumar@...aro.org>
Cc:	linaro-kernel@...ts.linaro.org, linux-pm@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH] cpufreq: acpi: Allow new dynamics attributes to be added to acpi_cpufreq_attr

acpi_cpufreq_attr contains at least one dynamically populated (removed)
attribute today, cpb. But the code isn't friendly enough for new
attributes to be populated in a similar way.

Make some changes to allow new attributes to be easily added to the
struct.

Signed-off-by: Viresh Kumar <viresh.kumar@...aro.org>
---
Srinivas,

This should make it easy for you to add another dynamic entry into the
acpi_cpufreq_attr structure.

 drivers/cpufreq/acpi-cpufreq.c | 19 +++++++++----------
 1 file changed, 9 insertions(+), 10 deletions(-)

diff --git a/drivers/cpufreq/acpi-cpufreq.c b/drivers/cpufreq/acpi-cpufreq.c
index 59a7b380fbe2..c37617ddcc9e 100644
--- a/drivers/cpufreq/acpi-cpufreq.c
+++ b/drivers/cpufreq/acpi-cpufreq.c
@@ -866,7 +866,7 @@ static struct freq_attr *acpi_cpufreq_attr[] = {
 	&cpufreq_freq_attr_scaling_available_freqs,
 	&freqdomain_cpus,
 #ifdef CONFIG_X86_ACPI_CPUFREQ_CPB
-	&cpb,
+	NULL,	/* Extra space for cpb if required */
 #endif
 	NULL,
 };
@@ -917,6 +917,7 @@ static void acpi_cpufreq_boost_exit(void)
 
 static int __init acpi_cpufreq_init(void)
 {
+	struct freq_attr **attr;
 	int ret;
 
 	if (acpi_disabled)
@@ -932,6 +933,10 @@ static int __init acpi_cpufreq_init(void)
 	if (ret)
 		return ret;
 
+	/* Find first empty entry */
+	for (attr = acpi_cpufreq_attr; *attr; attr++)
+		;
+
 #ifdef CONFIG_X86_ACPI_CPUFREQ_CPB
 	/* this is a sysfs file with a strange name and an even stranger
 	 * semantic - per CPU instantiation, but system global effect.
@@ -939,17 +944,11 @@ static int __init acpi_cpufreq_init(void)
 	 * only if configured. This is considered legacy code, which
 	 * will probably be removed at some point in the future.
 	 */
-	if (!check_amd_hwpstate_cpu(0)) {
-		struct freq_attr **attr;
-
+	if (check_amd_hwpstate_cpu(0))
+		*attr++ = &cpb;
+	else
 		pr_debug("CPB unsupported, do not expose it\n");
 
-		for (attr = acpi_cpufreq_attr; *attr; attr++)
-			if (*attr == &cpb) {
-				*attr = NULL;
-				break;
-			}
-	}
 #endif
 	acpi_cpufreq_boost_init();
 
-- 
2.7.1.410.g6faf27b