[PATCH] Add suspend method to cpufreq core

In order to properly fix some issues with cpufreq vs. sleep on
PowerBooks, I had to add a suspend callback to the pmac_cpufreq driver.
I must force a switch to full speed before sleep and I switch back to
previous speed on resume.

I also added a driver flag to disable the warnings in suspend/resume
since it is expected in this case to have different speed (and I want it
to fixup the jiffies properly).

Signed-off-by: Benjamin Herrenschmidt <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

drivers/cpufreq/cpufreq.c

···
 	}
 	if ((val == CPUFREQ_PRECHANGE  && ci->old < ci->new) ||
 	    (val == CPUFREQ_POSTCHANGE && ci->old > ci->new) ||
-	    (val == CPUFREQ_RESUMECHANGE)) {
+	    (val == CPUFREQ_RESUMECHANGE || val == CPUFREQ_SUSPENDCHANGE)) {
 		loops_per_jiffy = cpufreq_scale(l_p_j_ref, l_p_j_ref_freq, ci->new);
 		dprintk("scaling loops_per_jiffy to %lu for frequency %u kHz\n", loops_per_jiffy, ci->new);
 	}
···
 
 
 /**
+ *	cpufreq_suspend - let the low level driver prepare for suspend
+ */
+
+static int cpufreq_suspend(struct sys_device * sysdev, u32 state)
+{
+	int cpu = sysdev->id;
+	unsigned int ret = 0;
+	unsigned int cur_freq = 0;
+	struct cpufreq_policy *cpu_policy;
+
+	dprintk("resuming cpu %u\n", cpu);
+
+	if (!cpu_online(cpu))
+		return 0;
+
+	/* we may be lax here as interrupts are off. Nonetheless
+	 * we need to grab the correct cpu policy, as to check
+	 * whether we really run on this CPU.
+	 */
+
+	cpu_policy = cpufreq_cpu_get(cpu);
+	if (!cpu_policy)
+		return -EINVAL;
+
+	/* only handle each CPU group once */
+	if (unlikely(cpu_policy->cpu != cpu)) {
+		cpufreq_cpu_put(cpu_policy);
+		return 0;
+	}
+
+	if (cpufreq_driver->suspend) {
+		ret = cpufreq_driver->suspend(cpu_policy, state);
+		if (ret) {
+			printk(KERN_ERR "cpufreq: suspend failed in ->suspend "
+					"step on CPU %u\n", cpu_policy->cpu);
+			cpufreq_cpu_put(cpu_policy);
+			return ret;
+		}
+	}
+
+
+	if (cpufreq_driver->flags & CPUFREQ_CONST_LOOPS)
+		goto out;
+
+	if (cpufreq_driver->get)
+		cur_freq = cpufreq_driver->get(cpu_policy->cpu);
+
+	if (!cur_freq || !cpu_policy->cur) {
+		printk(KERN_ERR "cpufreq: suspend failed to assert current "
+		       "frequency is what timing core thinks it is.\n");
+		goto out;
+	}
+
+	if (unlikely(cur_freq != cpu_policy->cur)) {
+		struct cpufreq_freqs freqs;
+
+		if (!(cpufreq_driver->flags & CPUFREQ_PM_NO_WARN))
+			printk(KERN_DEBUG "Warning: CPU frequency is %u, "
+			       "cpufreq assumed %u kHz.\n",
+			       cur_freq, cpu_policy->cur);
+
+		freqs.cpu = cpu;
+		freqs.old = cpu_policy->cur;
+		freqs.new = cur_freq;
+
+		notifier_call_chain(&cpufreq_transition_notifier_list,
+				    CPUFREQ_SUSPENDCHANGE, &freqs);
+		adjust_jiffies(CPUFREQ_SUSPENDCHANGE, &freqs);
+
+		cpu_policy->cur = cur_freq;
+	}
+
+ out:
+	cpufreq_cpu_put(cpu_policy);
+	return 0;
+}
+
+/**
  *	cpufreq_resume -  restore proper CPU frequency handling after resume
  *
  *	1.) resume CPUfreq hardware support (cpufreq_driver->resume())
  *	2.) if ->target and !CPUFREQ_CONST_LOOPS: verify we're in sync
- *	3.) schedule call cpufreq_update_policy() ASAP as interrupts are restored.
+ *	3.) schedule call cpufreq_update_policy() ASAP as interrupts are
+ *	    restored.
  */
 static int cpufreq_resume(struct sys_device * sysdev)
 {
···
 			cur_freq = cpufreq_driver->get(cpu_policy->cpu);
 
 		if (!cur_freq || !cpu_policy->cur) {
-			printk(KERN_ERR "cpufreq: resume failed to assert current frequency is what timing core thinks it is.\n");
+			printk(KERN_ERR "cpufreq: resume failed to assert "
+					"current frequency is what timing core "
+					"thinks it is.\n");
 			goto out;
 		}
 
···
 			struct cpufreq_freqs freqs;
 
 			printk(KERN_WARNING "Warning: CPU frequency is %u, "
-			       "cpufreq assumed %u kHz.\n", cur_freq, cpu_policy->cur);
+					"cpufreq assumed %u kHz.\n",
+					cur_freq, cpu_policy->cur);
 
 			freqs.cpu = cpu;
 			freqs.old = cpu_policy->cur;
 			freqs.new = cur_freq;
 
-			notifier_call_chain(&cpufreq_transition_notifier_list, CPUFREQ_RESUMECHANGE, &freqs);
+			notifier_call_chain(&cpufreq_transition_notifier_list,
+					CPUFREQ_RESUMECHANGE, &freqs);
 			adjust_jiffies(CPUFREQ_RESUMECHANGE, &freqs);
 
 			cpu_policy->cur = cur_freq;
···
 static struct sysdev_driver cpufreq_sysdev_driver = {
 	.add		= cpufreq_add_dev,
 	.remove		= cpufreq_remove_dev,
+	.suspend	= cpufreq_suspend,
 	.resume		= cpufreq_resume,
 };
 

include/linux/cpufreq.h

···
 #define CPUFREQ_PRECHANGE	(0)
 #define CPUFREQ_POSTCHANGE	(1)
 #define CPUFREQ_RESUMECHANGE	(8)
+#define CPUFREQ_SUSPENDCHANGE	(9)
 
 struct cpufreq_freqs {
 	unsigned int cpu;	/* cpu nr */
···
 
 	/* optional */
 	int	(*exit)		(struct cpufreq_policy *policy);
+	int	(*suspend)	(struct cpufreq_policy *policy, u32 state);
 	int	(*resume)	(struct cpufreq_policy *policy);
 	struct freq_attr	**attr;
 };
···
 #define CPUFREQ_CONST_LOOPS 	0x02	/* loops_per_jiffy or other kernel
 					 * "constants" aren't affected by
 					 * frequency transitions */
-
+#define CPUFREQ_PM_NO_WARN	0x04	/* don't warn on suspend/resume speed
+					 * mismatches */
 
 int cpufreq_register_driver(struct cpufreq_driver *driver_data);
 int cpufreq_unregister_driver(struct cpufreq_driver *driver_data);