[v2,4/7] thermal: int340x: processor_thermal: Support power floor notifications

diff --git a/Documentation/driver-api/thermal/intel_dptf.rst b/Documentation/driver-api/thermal/intel_dptf.rst
index 2d11e74ac665..55d90eafd94b 100644
--- a/Documentation/driver-api/thermal/intel_dptf.rst
+++ b/Documentation/driver-api/thermal/intel_dptf.rst
@@ -164,6 +164,14 @@  ABI.
 ``power_limit_1_tmax_us`` (RO)
 	Maximum powercap sysfs constraint_1_time_window_us for Intel RAPL
 
+``power_floor_status`` (RO)
+	When set to 1, hardware is not able to satisfy the requested power limit
+	via Intel RAPL.
+
+``power_floor_enable`` (RW)
+	When set to 1, enable reading and notification of power floor status.
+	Notifications are issued for changes in the power_floor_status attribute.
+
 :file:`/sys/bus/pci/devices/0000\:00\:04.0/`
 
 ``tcc_offset_degree_celsius`` (RW)
diff --git a/drivers/thermal/intel/int340x_thermal/Makefile b/drivers/thermal/intel/int340x_thermal/Makefile
index f33a3ad3bef3..fe3f43924525 100644
--- a/drivers/thermal/intel/int340x_thermal/Makefile
+++ b/drivers/thermal/intel/int340x_thermal/Makefile
@@ -12,5 +12,6 @@  obj-$(CONFIG_INT340X_THERMAL)	+= processor_thermal_rfim.o
 obj-$(CONFIG_INT340X_THERMAL)	+= processor_thermal_mbox.o
 obj-$(CONFIG_INT340X_THERMAL)	+= processor_thermal_wt_req.o
 obj-$(CONFIG_INT340X_THERMAL)	+= processor_thermal_wt_hint.o
+obj-$(CONFIG_INT340X_THERMAL)	+= processor_thermal_power_floor.o
 obj-$(CONFIG_INT3406_THERMAL)	+= int3406_thermal.o
 obj-$(CONFIG_ACPI_THERMAL_REL)	+= acpi_thermal_rel.o
diff --git a/drivers/thermal/intel/int340x_thermal/processor_thermal_device.c b/drivers/thermal/intel/int340x_thermal/processor_thermal_device.c
index 29ed7d0f7022..649f67fdf345 100644
--- a/drivers/thermal/intel/int340x_thermal/processor_thermal_device.c
+++ b/drivers/thermal/intel/int340x_thermal/processor_thermal_device.c
@@ -26,6 +26,48 @@  static ssize_t power_limit_##index##_##suffix##_show(struct device *dev, \
 	(unsigned long)proc_dev->power_limits[index].suffix * 1000); \
 }
 
+static ssize_t power_floor_status_show(struct device *dev,
+				       struct device_attribute *attr,
+				       char *buf)
+{
+	struct proc_thermal_device *proc_dev = dev_get_drvdata(dev);
+	int ret;
+
+	ret = proc_thermal_read_power_floor_status(proc_dev);
+
+	return sysfs_emit(buf, "%d\n", ret);
+}
+
+static ssize_t power_floor_enable_show(struct device *dev,
+				       struct device_attribute *attr,
+				       char *buf)
+{
+	struct proc_thermal_device *proc_dev = dev_get_drvdata(dev);
+	bool ret;
+
+	ret = proc_thermal_power_floor_get_state(proc_dev);
+
+	return sysfs_emit(buf, "%d\n", ret);
+}
+
+static ssize_t power_floor_enable_store(struct device *dev,
+					struct device_attribute *attr,
+					const char *buf, size_t count)
+{
+	struct proc_thermal_device *proc_dev = dev_get_drvdata(dev);
+	u8 state;
+	int ret;
+
+	if (kstrtou8(buf, 0, &state))
+		return -EINVAL;
+
+	ret = proc_thermal_power_floor_set_state(proc_dev, !!state);
+	if (ret)
+		return ret;
+
+	return count;
+}
+
 POWER_LIMIT_SHOW(0, min_uw)
 POWER_LIMIT_SHOW(0, max_uw)
 POWER_LIMIT_SHOW(0, step_uw)
@@ -50,6 +92,9 @@  static DEVICE_ATTR_RO(power_limit_1_step_uw);
 static DEVICE_ATTR_RO(power_limit_1_tmin_us);
 static DEVICE_ATTR_RO(power_limit_1_tmax_us);
 
+static DEVICE_ATTR_RO(power_floor_status);
+static DEVICE_ATTR_RW(power_floor_enable);
+
 static struct attribute *power_limit_attrs[] = {
 	&dev_attr_power_limit_0_min_uw.attr,
 	&dev_attr_power_limit_1_min_uw.attr,
@@ -61,12 +106,30 @@  static struct attribute *power_limit_attrs[] = {
 	&dev_attr_power_limit_1_tmin_us.attr,
 	&dev_attr_power_limit_0_tmax_us.attr,
 	&dev_attr_power_limit_1_tmax_us.attr,
+	&dev_attr_power_floor_status.attr,
+	&dev_attr_power_floor_enable.attr,
 	NULL
 };
 
+static umode_t power_limit_attr_visible(struct kobject *kobj, struct attribute *attr, int unused)
+{
+	struct device *dev = kobj_to_dev(kobj);
+	struct proc_thermal_device *proc_dev;
+
+	if (attr != &dev_attr_power_floor_status.attr && attr != &dev_attr_power_floor_enable.attr)
+		return attr->mode;
+
+	proc_dev = dev_get_drvdata(dev);
+	if (!proc_dev || !(proc_dev->mmio_feature_mask & PROC_THERMAL_FEATURE_POWER_FLOOR))
+		return 0;
+
+	return attr->mode;
+}
+
 static const struct attribute_group power_limit_attribute_group = {
 	.attrs = power_limit_attrs,
-	.name = "power_limits"
+	.name = "power_limits",
+	.is_visible = power_limit_attr_visible,
 };
 
 static ssize_t tcc_offset_degree_celsius_show(struct device *dev,
@@ -380,6 +443,9 @@  void proc_thermal_mmio_remove(struct pci_dev *pdev, struct proc_thermal_device *
 	    proc_priv->mmio_feature_mask & PROC_THERMAL_FEATURE_DVFS)
 		proc_thermal_rfim_remove(pdev);
 
+	if (proc_priv->mmio_feature_mask & PROC_THERMAL_FEATURE_POWER_FLOOR)
+		proc_thermal_power_floor_set_state(proc_priv, false);
+
 	if (proc_priv->mmio_feature_mask & PROC_THERMAL_FEATURE_WT_REQ)
 		proc_thermal_wt_req_remove(pdev);
 	else if (proc_priv->mmio_feature_mask & PROC_THERMAL_FEATURE_WT_HINT)
diff --git a/drivers/thermal/intel/int340x_thermal/processor_thermal_device.h b/drivers/thermal/intel/int340x_thermal/processor_thermal_device.h
index f9a381b3e55c..95c6013a33fb 100644
--- a/drivers/thermal/intel/int340x_thermal/processor_thermal_device.h
+++ b/drivers/thermal/intel/int340x_thermal/processor_thermal_device.h
@@ -63,6 +63,7 @@  struct rapl_mmio_regs {
 #define PROC_THERMAL_FEATURE_WT_REQ	0x08
 #define PROC_THERMAL_FEATURE_DLVR	0x10
 #define PROC_THERMAL_FEATURE_WT_HINT	0x20
+#define PROC_THERMAL_FEATURE_POWER_FLOOR	0x40
 
 #if IS_ENABLED(CONFIG_PROC_THERMAL_MMIO_RAPL)
 int proc_thermal_rapl_add(struct pci_dev *pdev, struct proc_thermal_device *proc_priv);
@@ -94,6 +95,13 @@  void proc_thermal_wt_req_remove(struct pci_dev *pdev);
 #define SOC_WT_RES_INT_STATUS_OFFSET	0x5B18
 #define SOC_WT_RES_INT_STATUS_MASK	GENMASK_ULL(3, 2)
 
+int proc_thermal_read_power_floor_status(struct proc_thermal_device *proc_priv);
+int proc_thermal_power_floor_set_state(struct proc_thermal_device *proc_priv, bool enable);
+bool proc_thermal_power_floor_get_state(struct proc_thermal_device *proc_priv);
+void proc_thermal_power_floor_intr_callback(struct pci_dev *pdev,
+					    struct proc_thermal_device *proc_priv);
+bool proc_thermal_check_power_floor_intr(struct proc_thermal_device *proc_priv);
+
 int processor_thermal_send_mbox_read_cmd(struct pci_dev *pdev, u16 id, u64 *resp);
 int processor_thermal_send_mbox_write_cmd(struct pci_dev *pdev, u16 id, u32 data);
 int processor_thermal_mbox_interrupt_config(struct pci_dev *pdev, bool enable, int enable_bit,
diff --git a/drivers/thermal/intel/int340x_thermal/processor_thermal_power_floor.c b/drivers/thermal/intel/int340x_thermal/processor_thermal_power_floor.c
new file mode 100644
index 000000000000..a1a108407f0f
--- /dev/null
+++ b/drivers/thermal/intel/int340x_thermal/processor_thermal_power_floor.c
@@ -0,0 +1,126 @@ 
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Processor thermal device module for registering and processing
+ * power floor. When the hardware reduces the power to the minimum
+ * possible, the power floor is notified via an interrupt.
+ *
+ * Operation:
+ * When user space enables power floor reporting:
+ * - Use mailbox to:
+ *	Enable processor thermal device interrupt
+ *
+ * - Current status of power floor is read from offset 0x5B18
+ *   bit 39.
+ *
+ * Two interface functions are provided to call when there is a
+ * thermal device interrupt:
+ * - proc_thermal_power_floor_intr():
+ *	Check if the interrupt is for change in power floor.
+ *	Called from interrupt context.
+ *
+ * - proc_thermal_power_floor_intr_callback():
+ *	Callback for interrupt processing in thread context. This involves
+ *	sending notification to user space that there is a change in the
+ *	power floor status.
+ *
+ * Copyright (c) 2023, Intel Corporation.
+ */
+
+#include <linux/pci.h>
+#include "processor_thermal_device.h"
+
+#define SOC_POWER_FLOOR_STATUS		BIT(39)
+#define SOC_POWER_FLOOR_SHIFT		39
+
+#define SOC_POWER_FLOOR_INT_ENABLE_BIT	31
+#define SOC_POWER_FLOOR_INT_ACTIVE	BIT(3)
+
+int proc_thermal_read_power_floor_status(struct proc_thermal_device *proc_priv)
+{
+	u64 status = 0;
+
+	status = readq(proc_priv->mmio_base + SOC_WT_RES_INT_STATUS_OFFSET);
+	return (status & SOC_POWER_FLOOR_STATUS) >> SOC_POWER_FLOOR_SHIFT;
+}
+EXPORT_SYMBOL_NS_GPL(proc_thermal_read_power_floor_status, INT340X_THERMAL);
+
+static bool enable_state;
+static DEFINE_MUTEX(pf_lock);
+
+int proc_thermal_power_floor_set_state(struct proc_thermal_device *proc_priv, bool enable)
+{
+	int ret = 0;
+
+	mutex_lock(&pf_lock);
+	if (enable_state == enable)
+		goto pf_unlock;
+
+	/*
+	 * Time window parameter is not applicable to power floor interrupt configuration.
+	 * Hence use -1 for time window.
+	 */
+	ret = processor_thermal_mbox_interrupt_config(to_pci_dev(proc_priv->dev), enable,
+						      SOC_POWER_FLOOR_INT_ENABLE_BIT, -1);
+	if (!ret)
+		enable_state = enable;
+
+pf_unlock:
+	mutex_unlock(&pf_lock);
+
+	return ret;
+}
+EXPORT_SYMBOL_NS_GPL(proc_thermal_power_floor_set_state, INT340X_THERMAL);
+
+bool proc_thermal_power_floor_get_state(struct proc_thermal_device *proc_priv)
+{
+	return enable_state;
+}
+EXPORT_SYMBOL_NS_GPL(proc_thermal_power_floor_get_state, INT340X_THERMAL);
+
+/**
+ * proc_thermal_check_power_floor_intr() - Check power floor interrupt.
+ * @proc_priv: Processor thermal device instance.
+ *
+ * Callback to check if the interrupt for power floor is active.
+ *
+ * Context: Called from interrupt context.
+ *
+ * Return: true if power floor is active, false when not active.
+ */
+bool proc_thermal_check_power_floor_intr(struct proc_thermal_device *proc_priv)
+{
+	u64 int_status;
+
+	int_status = readq(proc_priv->mmio_base + SOC_WT_RES_INT_STATUS_OFFSET);
+	return !!(int_status & SOC_POWER_FLOOR_INT_ACTIVE);
+}
+EXPORT_SYMBOL_NS_GPL(proc_thermal_check_power_floor_intr, INT340X_THERMAL);
+
+/**
+ * proc_thermal_power_floor_intr_callback() - Process power floor notification
+ * @pdev:	PCI device instance
+ * @proc_priv: Processor thermal device instance.
+ *
+ * Check if the power floor interrupt is active, if active send notification to
+ * user space for the attribute "power_limits", so that user can read the attribute
+ * and take action.
+ *
+ * Context: Called from interrupt thread context.
+ *
+ * Return: None.
+ */
+void proc_thermal_power_floor_intr_callback(struct pci_dev *pdev,
+					    struct proc_thermal_device *proc_priv)
+{
+	u64 status;
+
+	status = readq(proc_priv->mmio_base + SOC_WT_RES_INT_STATUS_OFFSET);
+	if (!(status & SOC_POWER_FLOOR_INT_ACTIVE))
+		return;
+
+	sysfs_notify(&pdev->dev.kobj, "power_limits", "power_floor_status");
+}
+EXPORT_SYMBOL_NS_GPL(proc_thermal_power_floor_intr_callback, INT340X_THERMAL);
+
+MODULE_IMPORT_NS(INT340X_THERMAL);
+MODULE_LICENSE("GPL");