linux-kernel - [PATCH V2 03/10] powerpc: macintosh: Switch to QoS requests instead of cpufreq notifier

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Message-Id: <8fab346b73991afcc6bc602253c973e5d4ecde95.1563862014.git.viresh.kumar@linaro.org>
Date:   Tue, 23 Jul 2019 11:44:03 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Rafael Wysocki <rjw@...ysocki.net>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>
Cc:     Viresh Kumar <viresh.kumar@...aro.org>, linux-pm@...r.kernel.org,
        Vincent Guittot <vincent.guittot@...aro.org>,
        linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: [PATCH V2 03/10] powerpc: macintosh: Switch to QoS requests instead of cpufreq notifier

The cpufreq core now takes the min/max frequency constraints via QoS
requests and the CPUFREQ_ADJUST notifier shall get removed later on.

Switch over to using the QoS request for maximum frequency constraint
for windfarm_cpufreq_clamp driver.

Signed-off-by: Viresh Kumar <viresh.kumar@...aro.org>
---
 drivers/macintosh/windfarm_cpufreq_clamp.c | 77 ++++++++++++++--------
 1 file changed, 50 insertions(+), 27 deletions(-)

diff --git a/drivers/macintosh/windfarm_cpufreq_clamp.c b/drivers/macintosh/windfarm_cpufreq_clamp.c
index 52fd5fca89a0..705c6200814b 100644
--- a/drivers/macintosh/windfarm_cpufreq_clamp.c
+++ b/drivers/macintosh/windfarm_cpufreq_clamp.c
@@ -3,9 +3,11 @@
 #include <linux/errno.h>
 #include <linux/kernel.h>
 #include <linux/delay.h>
+#include <linux/pm_qos.h>
 #include <linux/slab.h>
 #include <linux/init.h>
 #include <linux/wait.h>
+#include <linux/cpu.h>
 #include <linux/cpufreq.h>
 
 #include <asm/prom.h>
@@ -16,36 +18,24 @@
 
 static int clamped;
 static struct wf_control *clamp_control;
-
-static int clamp_notifier_call(struct notifier_block *self,
-			       unsigned long event, void *data)
-{
-	struct cpufreq_policy *p = data;
-	unsigned long max_freq;
-
-	if (event != CPUFREQ_ADJUST)
-		return 0;
-
-	max_freq = clamped ? (p->cpuinfo.min_freq) : (p->cpuinfo.max_freq);
-	cpufreq_verify_within_limits(p, 0, max_freq);
-
-	return 0;
-}
-
-static struct notifier_block clamp_notifier = {
-	.notifier_call = clamp_notifier_call,
-};
+static struct dev_pm_qos_request qos_req;
+static unsigned int min_freq, max_freq;
 
 static int clamp_set(struct wf_control *ct, s32 value)
 {
-	if (value)
+	unsigned int freq;
+
+	if (value) {
+		freq = min_freq;
 		printk(KERN_INFO "windfarm: Clamping CPU frequency to "
 		       "minimum !\n");
-	else
+	} else {
+		freq = max_freq;
 		printk(KERN_INFO "windfarm: CPU frequency unclamped !\n");
+	}
 	clamped = value;
-	cpufreq_update_policy(0);
-	return 0;
+
+	return dev_pm_qos_update_request(&qos_req, freq);
 }
 
 static int clamp_get(struct wf_control *ct, s32 *value)
@@ -74,27 +64,60 @@ static const struct wf_control_ops clamp_ops = {
 
 static int __init wf_cpufreq_clamp_init(void)
 {
+	struct cpufreq_policy *policy;
 	struct wf_control *clamp;
+	struct device *dev;
+	int ret;
+
+	policy = cpufreq_cpu_get(0);
+	if (!policy) {
+		pr_warn("%s: cpufreq policy not found cpu0\n", __func__);
+		return -EPROBE_DEFER;
+	}
+
+	min_freq = policy->cpuinfo.min_freq;
+	max_freq = policy->cpuinfo.max_freq;
+	cpufreq_cpu_put(policy);
+
+	dev = get_cpu_device(0);
+	if (unlikely(!dev)) {
+		pr_warn("%s: No cpu device for cpu0\n", __func__);
+		return -ENODEV;
+	}
 
 	clamp = kmalloc(sizeof(struct wf_control), GFP_KERNEL);
 	if (clamp == NULL)
 		return -ENOMEM;
-	cpufreq_register_notifier(&clamp_notifier, CPUFREQ_POLICY_NOTIFIER);
+
+	ret = dev_pm_qos_add_request(dev, &qos_req, DEV_PM_QOS_MAX_FREQUENCY,
+				     max_freq);
+	if (ret < 0) {
+		pr_err("%s: Failed to add freq constraint (%d)\n", __func__,
+		       ret);
+		goto free;
+	}
+
 	clamp->ops = &clamp_ops;
 	clamp->name = "cpufreq-clamp";
-	if (wf_register_control(clamp))
+	ret = wf_register_control(clamp);
+	if (ret)
 		goto fail;
 	clamp_control = clamp;
 	return 0;
  fail:
+	dev_pm_qos_remove_request(&qos_req);
+
+ free:
 	kfree(clamp);
-	return -ENODEV;
+	return ret;
 }
 
 static void __exit wf_cpufreq_clamp_exit(void)
 {
-	if (clamp_control)
+	if (clamp_control) {
 		wf_unregister_control(clamp_control);
+		dev_pm_qos_remove_request(&qos_req);
+	}
 }
 
 
-- 
2.21.0.rc0.269.g1a574e7a288b