[PATCH v3 4/6] cpufreq: powernv: Call throttle_check() on receiving OCC_THROTTLE

[Shilpasri G Bhat]

Re-evaluate the chip's throttled state on recieving OCC_THROTTLE
notification by executing *throttle_check() on any one of the cpu on
the chip. This is a sanity check to verify if we were indeed
throttled/unthrottled after receiving OCC_THROTTLE notification.

We cannot call *throttle_check() directly from the notification
handler because we could be handling chip1's notification in chip2. So
initiate an smp_call to execute *throttle_check(). We are irq-disabled
in the notification handler, so use a worker thread to smp_call
throttle_check() on any of the cpu in the chipmask.

Signed-off-by: Shilpasri G Bhat <shilpa.bhat at linux.vnet.ibm.com>
---
 drivers/cpufreq/powernv-cpufreq.c | 28 ++++++++++++++++++++++++++--
 1 file changed, 26 insertions(+), 2 deletions(-)

diff --git a/drivers/cpufreq/powernv-cpufreq.c b/drivers/cpufreq/powernv-cpufreq.c
index 9268424..9618813 100644
--- a/drivers/cpufreq/powernv-cpufreq.c
+++ b/drivers/cpufreq/powernv-cpufreq.c
@@ -50,6 +50,8 @@ static bool rebooting, throttled, occ_reset;
 static struct chip {
 	unsigned int id;
 	bool throttled;
+	cpumask_t mask;
+	struct work_struct throttle;
 } *chips;
 
 static int nr_chips;
@@ -310,8 +312,9 @@ static inline unsigned int get_nominal_index(void)
 	return powernv_pstate_info.max - powernv_pstate_info.nominal;
 }
 
-static void powernv_cpufreq_throttle_check(unsigned int cpu)
+static void powernv_cpufreq_throttle_check(void *data)
 {
+	unsigned int cpu = smp_processor_id();
 	unsigned long pmsr;
 	int pmsr_pmax, pmsr_lp, i;
 
@@ -373,7 +376,7 @@ static int powernv_cpufreq_target_index(struct cpufreq_policy *policy,
 		return 0;
 
 	if (!throttled)
-		powernv_cpufreq_throttle_check(smp_processor_id());
+		powernv_cpufreq_throttle_check(NULL);
 
 	freq_data.pstate_id = powernv_freqs[new_index].driver_data;
 
@@ -418,6 +421,14 @@ static struct notifier_block powernv_cpufreq_reboot_nb = {
 	.notifier_call = powernv_cpufreq_reboot_notifier,
 };
 
+void powernv_cpufreq_work_fn(struct work_struct *work)
+{
+	struct chip *chip = container_of(work, struct chip, throttle);
+
+	smp_call_function_any(&chip->mask,
+			      powernv_cpufreq_throttle_check, NULL, 0);
+}
+
 static char throttle_reason[][30] = {
 					"No throttling",
 					"Power Cap",
@@ -433,6 +444,7 @@ static int powernv_cpufreq_occ_msg(struct notifier_block *nb,
 	struct opal_msg *occ_msg = msg;
 	uint64_t token;
 	uint64_t chip_id, reason;
+	int i;
 
 	if (msg_type != OPAL_MSG_OCC)
 		return 0;
@@ -466,6 +478,10 @@ static int powernv_cpufreq_occ_msg(struct notifier_block *nb,
 			occ_reset = false;
 			throttled = false;
 			pr_info("OCC: Active\n");
+
+			for (i = 0; i < nr_chips; i++)
+				schedule_work(&chips[i].throttle);
+
 			return 0;
 		}
 
@@ -476,6 +492,12 @@ static int powernv_cpufreq_occ_msg(struct notifier_block *nb,
 		else if (!reason)
 			pr_info("OCC: Chip %u %s\n", (unsigned int)chip_id,
 				throttle_reason[reason]);
+		else
+			return 0;
+
+		for (i = 0; i < nr_chips; i++)
+			if (chips[i].id == chip_id)
+				schedule_work(&chips[i].throttle);
 	}
 	return 0;
 }
@@ -527,6 +549,8 @@ static int init_chip_info(void)
 	for (i = 0; i < nr_chips; i++) {
 		chips[i].id = chip[i];
 		chips[i].throttled = false;
+		cpumask_copy(&chips[i].mask, cpumask_of_node(chip[i]));
+		INIT_WORK(&chips[i].throttle, powernv_cpufreq_work_fn);
 	}
 
 	return 0;
-- 
1.9.3