regulator: cpr3-regulator: add support for configuring CPR IRQ affinity

Add support to configure the CPR interrupt affinity via a CPR3
controller device tree node.  This can be used to avoid servicing
CPR interrupts triggered by a CPU enterring power collapse on the
CPU that just power collapsed.

Change-Id: I4c04a2c255a6bd249c888c0dd0dbda19b8436be2
CRs-Fixed: 949650
Signed-off-by: David Collins <collinsd@codeaurora.org>

Documentation/devicetree/bindings/regulator/cpr3-hmss-regulator.txt

@@ -313,6 +313,7 @@ apcc_cpr: cpr3-ctrl@99e8000 {
 	clock-names = "core_clk";
 	interrupts = <0 48 0>, <0 47 0>;
 	interrupt-names = "cpr", "ceiling";
+	qcom,cpr-interrupt-affinity = <&CPU0 &CPU1>;
 	qcom,cpr-ctrl-name = "apcc";
 
 	qcom,cpr-sensor-time = <1000>;

Documentation/devicetree/bindings/regulator/cpr3-regulator.txt

@@ -104,6 +104,12 @@ Platform independent properties:
 		    must be specified.  "ceiling" may be specified for some
 		    platforms.
 
+- qcom,cpr-interrupt-affinity
+	Usage:      optional
+	Value type: <prop-encoded-array>
+	Definition: A list of CPU phandles which correspond to the cores that
+		    the "cpr" interrupt should have affinity for.
+
 - qcom,cpr-sensor-time
 	Usage:      required
 	Value type: <u32>

drivers/regulator/cpr3-regulator.c

@@ -5778,6 +5778,31 @@ int cpr3_regulator_resume(struct cpr3_controller *ctrl)
 	return 0;
 }
 
+/**
+ * cpr3_regulator_cpu_hotplug_callback() - reset CPR IRQ affinity when a CPU is
+ *		brought online via hotplug
+ * @nb:			Pointer to the notifier block
+ * @action:		hotplug action
+ * @hcpu:		long value corresponding to the CPU number
+ *
+ * Return: NOTIFY_OK
+ */
+static int cpr3_regulator_cpu_hotplug_callback(struct notifier_block *nb,
+					    unsigned long action, void *hcpu)
+{
+	struct cpr3_controller *ctrl = container_of(nb, struct cpr3_controller,
+					cpu_hotplug_notifier);
+	int cpu = (long)hcpu;
+
+	action &= ~CPU_TASKS_FROZEN;
+
+	if (action == CPU_ONLINE
+	    && cpumask_test_cpu(cpu, &ctrl->irq_affinity_mask))
+		irq_set_affinity(ctrl->irq, &ctrl->irq_affinity_mask);
+
+	return NOTIFY_OK;
+}
+
 /**
  * cpr3_regulator_validate_controller() - verify the data passed in via the
  *		cpr3_controller data structure
@@ -5975,6 +6000,14 @@ int cpr3_regulator_register(struct platform_device *pdev,
 		}
 	}
 
+	if (ctrl->irq && !cpumask_empty(&ctrl->irq_affinity_mask)) {
+		irq_set_affinity(ctrl->irq, &ctrl->irq_affinity_mask);
+
+		ctrl->cpu_hotplug_notifier.notifier_call
+			= cpr3_regulator_cpu_hotplug_callback;
+		register_hotcpu_notifier(&ctrl->cpu_hotplug_notifier);
+	}
+
 	mutex_lock(&cpr3_controller_list_mutex);
 	cpr3_regulator_debugfs_ctrl_add(ctrl);
 	list_add(&ctrl->list, &cpr3_controller_list);

drivers/regulator/cpr3-regulator.h

@@ -535,6 +535,10 @@ struct cpr3_aging_sensor_info {
  * @iface_clk:		Pointer to the CPR3 interface clock (platform specific)
  * @bus_clk:		Pointer to the CPR3 bus clock (platform specific)
  * @irq:		CPR interrupt number
+ * @irq_affinity_mask:	The cpumask for the CPUs which the CPR interrupt should
+ *			have affinity for
+ * @cpu_hotplug_notifier: CPU hotplug notifier used to reset IRQ affinity when a
+ *			CPU is brought back online
  * @ceiling_irq:	Interrupt number for the interrupt that is triggered
  *			when hardware closed-loop attempts to exceed the ceiling
  *			voltage
@@ -695,6 +699,8 @@ struct cpr3_controller {
 	struct clk		*iface_clk;
 	struct clk		*bus_clk;
 	int			irq;
+	struct cpumask		irq_affinity_mask;
+	struct notifier_block	cpu_hotplug_notifier;
 	int			ceiling_irq;
 	struct msm_apm_ctrl_dev *apm;
 	int			apm_threshold_volt;

drivers/regulator/cpr3-util.c

@@ -18,6 +18,7 @@
 
 #define pr_fmt(fmt) "%s: " fmt, __func__
 
+#include <linux/cpumask.h>
 #include <linux/device.h>
 #include <linux/io.h>
 #include <linux/kernel.h>
@@ -979,6 +980,46 @@ int cpr3_parse_common_thread_data(struct cpr3_thread *thread)
 	return rc;
 }
 
+/**
+ * cpr3_parse_irq_affinity() - parse CPR IRQ affinity information
+ * @ctrl:		Pointer to the CPR3 controller
+ *
+ * Return: 0 on success, errno on failure
+ */
+static int cpr3_parse_irq_affinity(struct cpr3_controller *ctrl)
+{
+	struct device_node *cpu_node;
+	int i, cpu;
+	int len = 0;
+
+	if (!of_find_property(ctrl->dev->of_node, "qcom,cpr-interrupt-affinity",
+				&len)) {
+		/* No IRQ affinity required */
+		return 0;
+	}
+
+	len /= sizeof(u32);
+
+	for (i = 0; i < len; i++) {
+		cpu_node = of_parse_phandle(ctrl->dev->of_node,
+					    "qcom,cpr-interrupt-affinity", i);
+		if (!cpu_node) {
+			cpr3_err(ctrl, "could not find CPU node %d\n", i);
+			return -EINVAL;
+		}
+
+		for_each_possible_cpu(cpu) {
+			if (of_get_cpu_node(cpu, NULL) == cpu_node) {
+				cpumask_set_cpu(cpu, &ctrl->irq_affinity_mask);
+				break;
+			}
+		}
+		of_node_put(cpu_node);
+	}
+
+	return 0;
+}
+
 /**
  * cpr3_parse_common_ctrl_data() - parse common CPR3 controller properties from
  *		device tree
@@ -1045,6 +1086,10 @@ int cpr3_parse_common_ctrl_data(struct cpr3_controller *ctrl)
 	ctrl->cpr_allowed_sw = of_property_read_bool(ctrl->dev->of_node,
 			"qcom,cpr-enable");
 
+	rc = cpr3_parse_irq_affinity(ctrl);
+	if (rc)
+		return rc;
+
 	/* Aging reference voltage is optional */
 	ctrl->aging_ref_volt = 0;
 	of_property_read_u32(ctrl->dev->of_node, "qcom,cpr-aging-ref-voltage",