diff --git a/drivers/platform/x86/intel_speed_select_if/isst_if_common.c b/drivers/platform/x86/intel_speed_select_if/isst_if_common.c
index ab2bb4862dc8..0e16cbf685d0 100644
--- a/drivers/platform/x86/intel_speed_select_if/isst_if_common.c
+++ b/drivers/platform/x86/intel_speed_select_if/isst_if_common.c
@@ -7,14 +7,22 @@
  * Author: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
  */
 
+#include <linux/cpufeature.h>
+#include <linux/cpuhotplug.h>
 #include <linux/fs.h>
 #include <linux/miscdevice.h>
 #include <linux/module.h>
+#include <linux/pci.h>
+#include <linux/sched/signal.h>
+#include <linux/slab.h>
 #include <linux/uaccess.h>
 #include <uapi/linux/isst_if.h>
 
 #include "isst_if_common.h"
 
+#define MSR_THREAD_ID_INFO	0x53
+#define MSR_CPU_BUS_NUMBER	0x128
+
 static struct isst_if_cmd_cb punit_callbacks[ISST_IF_DEV_MAX];
 
 static int isst_if_get_platform_info(void __user *argp)
@@ -33,6 +41,99 @@ static int isst_if_get_platform_info(void __user *argp)
 	return 0;
 }
 
+
+struct isst_if_cpu_info {
+	/* For BUS 0 and BUS 1 only, which we need for PUNIT interface */
+	int bus_info[2];
+	int punit_cpu_id;
+};
+
+static struct isst_if_cpu_info *isst_cpu_info;
+
+/**
+ * isst_if_get_pci_dev() - Get the PCI device instance for a CPU
+ * @cpu: Logical CPU number.
+ * @bus_number: The bus number assigned by the hardware.
+ * @dev: The device number assigned by the hardware.
+ * @fn: The function number assigned by the hardware.
+ *
+ * Using cached bus information, find out the PCI device for a bus number,
+ * device and function.
+ *
+ * Return: Return pci_dev pointer or NULL.
+ */
+struct pci_dev *isst_if_get_pci_dev(int cpu, int bus_no, int dev, int fn)
+{
+	int bus_number;
+
+	if (bus_no < 0 || bus_no > 1 || cpu < 0 || cpu >= nr_cpu_ids ||
+	    cpu >= num_possible_cpus())
+		return NULL;
+
+	bus_number = isst_cpu_info[cpu].bus_info[bus_no];
+	if (bus_number < 0)
+		return NULL;
+
+	return pci_get_domain_bus_and_slot(0, bus_number, PCI_DEVFN(dev, fn));
+}
+EXPORT_SYMBOL_GPL(isst_if_get_pci_dev);
+
+static int isst_if_cpu_online(unsigned int cpu)
+{
+	u64 data;
+	int ret;
+
+	ret = rdmsrl_safe(MSR_CPU_BUS_NUMBER, &data);
+	if (ret) {
+		/* This is not a fatal error on MSR mailbox only I/F */
+		isst_cpu_info[cpu].bus_info[0] = -1;
+		isst_cpu_info[cpu].bus_info[1] = -1;
+	} else {
+		isst_cpu_info[cpu].bus_info[0] = data & 0xff;
+		isst_cpu_info[cpu].bus_info[1] = (data >> 8) & 0xff;
+	}
+
+	ret = rdmsrl_safe(MSR_THREAD_ID_INFO, &data);
+	if (ret) {
+		isst_cpu_info[cpu].punit_cpu_id = -1;
+		return ret;
+	}
+	isst_cpu_info[cpu].punit_cpu_id = data;
+
+	return 0;
+}
+
+static int isst_if_online_id;
+
+static int isst_if_cpu_info_init(void)
+{
+	int ret;
+
+	isst_cpu_info = kcalloc(num_possible_cpus(),
+				sizeof(*isst_cpu_info),
+				GFP_KERNEL);
+	if (!isst_cpu_info)
+		return -ENOMEM;
+
+	ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN,
+				"platform/x86/isst-if:online",
+				isst_if_cpu_online, NULL);
+	if (ret < 0) {
+		kfree(isst_cpu_info);
+		return ret;
+	}
+
+	isst_if_online_id = ret;
+
+	return 0;
+}
+
+static void isst_if_cpu_info_exit(void)
+{
+	cpuhp_remove_state(isst_if_online_id);
+	kfree(isst_cpu_info);
+};
+
 static long isst_if_def_ioctl(struct file *file, unsigned int cmd,
 			      unsigned long arg)
 {
@@ -145,9 +246,18 @@ int isst_if_cdev_register(int device_type, struct isst_if_cmd_cb *cb)
 		return -EAGAIN;
 	}
 	if (!misc_usage_count) {
+		int ret;
+
 		misc_device_ret = misc_register(&isst_if_char_driver);
 		if (misc_device_ret)
 			goto unlock_exit;
+
+		ret = isst_if_cpu_info_init();
+		if (ret) {
+			misc_deregister(&isst_if_char_driver);
+			misc_device_ret = ret;
+			goto unlock_exit;
+		}
 	}
 	memcpy(&punit_callbacks[device_type], cb, sizeof(*cb));
 	punit_callbacks[device_type].registered = 1;
@@ -173,8 +283,10 @@ void isst_if_cdev_unregister(int device_type)
 	mutex_lock(&punit_misc_dev_lock);
 	misc_usage_count--;
 	punit_callbacks[device_type].registered = 0;
-	if (!misc_usage_count && !misc_device_ret)
+	if (!misc_usage_count && !misc_device_ret) {
 		misc_deregister(&isst_if_char_driver);
+		isst_if_cpu_info_exit();
+	}
 	mutex_unlock(&punit_misc_dev_lock);
 }
 EXPORT_SYMBOL_GPL(isst_if_cdev_unregister);
diff --git a/drivers/platform/x86/intel_speed_select_if/isst_if_common.h b/drivers/platform/x86/intel_speed_select_if/isst_if_common.h
index 11f339226fb4..dade77c58b22 100644
--- a/drivers/platform/x86/intel_speed_select_if/isst_if_common.h
+++ b/drivers/platform/x86/intel_speed_select_if/isst_if_common.h
@@ -57,4 +57,5 @@ struct isst_if_cmd_cb {
 /* Internal interface functions */
 int isst_if_cdev_register(int type, struct isst_if_cmd_cb *cb);
 void isst_if_cdev_unregister(int type);
+struct pci_dev *isst_if_get_pci_dev(int cpu, int bus, int dev, int fn);
 #endif