1 files changed, 134 insertions, 0 deletions
diff --git a/drivers/macintosh/windfarm_cpufreq_clamp.c b/drivers/macintosh/windfarm_cpufreq_clamp.c
new file mode 100644
index 000000000..28d18ef22
--- /dev/null
+++ b/drivers/macintosh/windfarm_cpufreq_clamp.c
@@ -0,0 +1,134 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include <linux/types.h>
+#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 "windfarm.h"
+
+#define VERSION "0.3"
+
+static int clamped;
+static struct wf_control *clamp_control;
+static struct freq_qos_request qos_req;
+static unsigned int min_freq, max_freq;
+
+static int clamp_set(struct wf_control *ct, s32 value)
+{
+	unsigned int freq;
+
+	if (value) {
+		freq = min_freq;
+		printk(KERN_INFO "windfarm: Clamping CPU frequency to "
+		       "minimum !\n");
+	} else {
+		freq = max_freq;
+		printk(KERN_INFO "windfarm: CPU frequency unclamped !\n");
+	}
+	clamped = value;
+
+	return freq_qos_update_request(&qos_req, freq);
+}
+
+static int clamp_get(struct wf_control *ct, s32 *value)
+{
+	*value = clamped;
+	return 0;
+}
+
+static s32 clamp_min(struct wf_control *ct)
+{
+	return 0;
+}
+
+static s32 clamp_max(struct wf_control *ct)
+{
+	return 1;
+}
+
+static const struct wf_control_ops clamp_ops = {
+	.set_value	= clamp_set,
+	.get_value	= clamp_get,
+	.get_min	= clamp_min,
+	.get_max	= clamp_max,
+	.owner		= THIS_MODULE,
+};
+
+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;
+
+	ret = freq_qos_add_request(&policy->constraints, &qos_req, FREQ_QOS_MAX,
+				   max_freq);
+
+	cpufreq_cpu_put(policy);
+
+	if (ret < 0) {
+		pr_err("%s: Failed to add freq constraint (%d)\n", __func__,
+		       ret);
+		return ret;
+	}
+
+	dev = get_cpu_device(0);
+	if (unlikely(!dev)) {
+		pr_warn("%s: No cpu device for cpu0\n", __func__);
+		ret = -ENODEV;
+		goto fail;
+	}
+
+	clamp = kmalloc(sizeof(struct wf_control), GFP_KERNEL);
+	if (clamp == NULL) {
+		ret = -ENOMEM;
+		goto fail;
+	}
+
+	clamp->ops = &clamp_ops;
+	clamp->name = "cpufreq-clamp";
+	ret = wf_register_control(clamp);
+	if (ret)
+		goto free;
+
+	clamp_control = clamp;
+	return 0;
+
+ free:
+	kfree(clamp);
+ fail:
+	freq_qos_remove_request(&qos_req);
+	return ret;
+}
+
+static void __exit wf_cpufreq_clamp_exit(void)
+{
+	if (clamp_control) {
+		wf_unregister_control(clamp_control);
+		freq_qos_remove_request(&qos_req);
+	}
+}
+
+
+module_init(wf_cpufreq_clamp_init);
+module_exit(wf_cpufreq_clamp_exit);
+
+MODULE_AUTHOR("Benjamin Herrenschmidt <benh@kernel.crashing.org>");
+MODULE_DESCRIPTION("CPU frequency clamp for PowerMacs thermal control");
+MODULE_LICENSE("GPL");
+