Adding upstream version 5.10.209.upstream/5.10.209

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1407 insertions, 0 deletions

diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c
new file mode 100644
index 000000000..b62348a7e
--- /dev/null
+++ b/drivers/acpi/cppc_acpi.c
@@ -0,0 +1,1407 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * CPPC (Collaborative Processor Performance Control) methods used by CPUfreq drivers.
+ *
+ * (C) Copyright 2014, 2015 Linaro Ltd.
+ * Author: Ashwin Chaugule <ashwin.chaugule@linaro.org>
+ *
+ * CPPC describes a few methods for controlling CPU performance using
+ * information from a per CPU table called CPC. This table is described in
+ * the ACPI v5.0+ specification. The table consists of a list of
+ * registers which may be memory mapped or hardware registers and also may
+ * include some static integer values.
+ *
+ * CPU performance is on an abstract continuous scale as against a discretized
+ * P-state scale which is tied to CPU frequency only. In brief, the basic
+ * operation involves:
+ *
+ * - OS makes a CPU performance request. (Can provide min and max bounds)
+ *
+ * - Platform (such as BMC) is free to optimize request within requested bounds
+ *   depending on power/thermal budgets etc.
+ *
+ * - Platform conveys its decision back to OS
+ *
+ * The communication between OS and platform occurs through another medium
+ * called (PCC) Platform Communication Channel. This is a generic mailbox like
+ * mechanism which includes doorbell semantics to indicate register updates.
+ * See drivers/mailbox/pcc.c for details on PCC.
+ *
+ * Finer details about the PCC and CPPC spec are available in the ACPI v5.1 and
+ * above specifications.
+ */
+
+#define pr_fmt(fmt)	"ACPI CPPC: " fmt
+
+#include <linux/cpufreq.h>
+#include <linux/delay.h>
+#include <linux/iopoll.h>
+#include <linux/ktime.h>
+#include <linux/rwsem.h>
+#include <linux/wait.h>
+
+#include <acpi/cppc_acpi.h>
+
+struct cppc_pcc_data {
+	struct mbox_chan *pcc_channel;
+	void __iomem *pcc_comm_addr;
+	bool pcc_channel_acquired;
+	unsigned int deadline_us;
+	unsigned int pcc_mpar, pcc_mrtt, pcc_nominal;
+
+	bool pending_pcc_write_cmd;	/* Any pending/batched PCC write cmds? */
+	bool platform_owns_pcc;		/* Ownership of PCC subspace */
+	unsigned int pcc_write_cnt;	/* Running count of PCC write commands */
+
+	/*
+	 * Lock to provide controlled access to the PCC channel.
+	 *
+	 * For performance critical usecases(currently cppc_set_perf)
+	 *	We need to take read_lock and check if channel belongs to OSPM
+	 * before reading or writing to PCC subspace
+	 *	We need to take write_lock before transferring the channel
+	 * ownership to the platform via a Doorbell
+	 *	This allows us to batch a number of CPPC requests if they happen
+	 * to originate in about the same time
+	 *
+	 * For non-performance critical usecases(init)
+	 *	Take write_lock for all purposes which gives exclusive access
+	 */
+	struct rw_semaphore pcc_lock;
+
+	/* Wait queue for CPUs whose requests were batched */
+	wait_queue_head_t pcc_write_wait_q;
+	ktime_t last_cmd_cmpl_time;
+	ktime_t last_mpar_reset;
+	int mpar_count;
+	int refcount;
+};
+
+/* Array to represent the PCC channel per subspace ID */
+static struct cppc_pcc_data *pcc_data[MAX_PCC_SUBSPACES];
+/* The cpu_pcc_subspace_idx contains per CPU subspace ID */
+static DEFINE_PER_CPU(int, cpu_pcc_subspace_idx);
+
+/*
+ * The cpc_desc structure contains the ACPI register details
+ * as described in the per CPU _CPC tables. The details
+ * include the type of register (e.g. PCC, System IO, FFH etc.)
+ * and destination addresses which lets us READ/WRITE CPU performance
+ * information using the appropriate I/O methods.
+ */
+static DEFINE_PER_CPU(struct cpc_desc *, cpc_desc_ptr);
+
+/* pcc mapped address + header size + offset within PCC subspace */
+#define GET_PCC_VADDR(offs, pcc_ss_id) (pcc_data[pcc_ss_id]->pcc_comm_addr + \
+						0x8 + (offs))
+
+/* Check if a CPC register is in PCC */
+#define CPC_IN_PCC(cpc) ((cpc)->type == ACPI_TYPE_BUFFER &&		\
+				(cpc)->cpc_entry.reg.space_id ==	\
+				ACPI_ADR_SPACE_PLATFORM_COMM)
+
+/* Evalutes to True if reg is a NULL register descriptor */
+#define IS_NULL_REG(reg) ((reg)->space_id ==  ACPI_ADR_SPACE_SYSTEM_MEMORY && \
+				(reg)->address == 0 &&			\
+				(reg)->bit_width == 0 &&		\
+				(reg)->bit_offset == 0 &&		\
+				(reg)->access_width == 0)
+
+/* Evalutes to True if an optional cpc field is supported */
+#define CPC_SUPPORTED(cpc) ((cpc)->type == ACPI_TYPE_INTEGER ?		\
+				!!(cpc)->cpc_entry.int_value :		\
+				!IS_NULL_REG(&(cpc)->cpc_entry.reg))
+/*
+ * Arbitrary Retries in case the remote processor is slow to respond
+ * to PCC commands. Keeping it high enough to cover emulators where
+ * the processors run painfully slow.
+ */
+#define NUM_RETRIES 500ULL
+
+#define define_one_cppc_ro(_name)		\
+static struct kobj_attribute _name =		\
+__ATTR(_name, 0444, show_##_name, NULL)
+
+#define to_cpc_desc(a) container_of(a, struct cpc_desc, kobj)
+
+#define show_cppc_data(access_fn, struct_name, member_name)		\
+	static ssize_t show_##member_name(struct kobject *kobj,		\
+				struct kobj_attribute *attr, char *buf)	\
+	{								\
+		struct cpc_desc *cpc_ptr = to_cpc_desc(kobj);		\
+		struct struct_name st_name = {0};			\
+		int ret;						\
+									\
+		ret = access_fn(cpc_ptr->cpu_id, &st_name);		\
+		if (ret)						\
+			return ret;					\
+									\
+		return scnprintf(buf, PAGE_SIZE, "%llu\n",		\
+				(u64)st_name.member_name);		\
+	}								\
+	define_one_cppc_ro(member_name)
+
+show_cppc_data(cppc_get_perf_caps, cppc_perf_caps, highest_perf);
+show_cppc_data(cppc_get_perf_caps, cppc_perf_caps, lowest_perf);
+show_cppc_data(cppc_get_perf_caps, cppc_perf_caps, nominal_perf);
+show_cppc_data(cppc_get_perf_caps, cppc_perf_caps, lowest_nonlinear_perf);
+show_cppc_data(cppc_get_perf_caps, cppc_perf_caps, lowest_freq);
+show_cppc_data(cppc_get_perf_caps, cppc_perf_caps, nominal_freq);
+
+show_cppc_data(cppc_get_perf_ctrs, cppc_perf_fb_ctrs, reference_perf);
+show_cppc_data(cppc_get_perf_ctrs, cppc_perf_fb_ctrs, wraparound_time);
+
+static ssize_t show_feedback_ctrs(struct kobject *kobj,
+		struct kobj_attribute *attr, char *buf)
+{
+	struct cpc_desc *cpc_ptr = to_cpc_desc(kobj);
+	struct cppc_perf_fb_ctrs fb_ctrs = {0};
+	int ret;
+
+	ret = cppc_get_perf_ctrs(cpc_ptr->cpu_id, &fb_ctrs);
+	if (ret)
+		return ret;
+
+	return scnprintf(buf, PAGE_SIZE, "ref:%llu del:%llu\n",
+			fb_ctrs.reference, fb_ctrs.delivered);
+}
+define_one_cppc_ro(feedback_ctrs);
+
+static struct attribute *cppc_attrs[] = {
+	&feedback_ctrs.attr,
+	&reference_perf.attr,
+	&wraparound_time.attr,
+	&highest_perf.attr,
+	&lowest_perf.attr,
+	&lowest_nonlinear_perf.attr,
+	&nominal_perf.attr,
+	&nominal_freq.attr,
+	&lowest_freq.attr,
+	NULL
+};
+
+static struct kobj_type cppc_ktype = {
+	.sysfs_ops = &kobj_sysfs_ops,
+	.default_attrs = cppc_attrs,
+};
+
+static int check_pcc_chan(int pcc_ss_id, bool chk_err_bit)
+{
+	int ret, status;
+	struct cppc_pcc_data *pcc_ss_data = pcc_data[pcc_ss_id];
+	struct acpi_pcct_shared_memory __iomem *generic_comm_base =
+		pcc_ss_data->pcc_comm_addr;
+
+	if (!pcc_ss_data->platform_owns_pcc)
+		return 0;
+
+	/*
+	 * Poll PCC status register every 3us(delay_us) for maximum of
+	 * deadline_us(timeout_us) until PCC command complete bit is set(cond)
+	 */
+	ret = readw_relaxed_poll_timeout(&generic_comm_base->status, status,
+					status & PCC_CMD_COMPLETE_MASK, 3,
+					pcc_ss_data->deadline_us);
+
+	if (likely(!ret)) {
+		pcc_ss_data->platform_owns_pcc = false;
+		if (chk_err_bit && (status & PCC_ERROR_MASK))
+			ret = -EIO;
+	}
+
+	if (unlikely(ret))
+		pr_err("PCC check channel failed for ss: %d. ret=%d\n",
+		       pcc_ss_id, ret);
+
+	return ret;
+}
+
+/*
+ * This function transfers the ownership of the PCC to the platform
+ * So it must be called while holding write_lock(pcc_lock)
+ */
+static int send_pcc_cmd(int pcc_ss_id, u16 cmd)
+{
+	int ret = -EIO, i;
+	struct cppc_pcc_data *pcc_ss_data = pcc_data[pcc_ss_id];
+	struct acpi_pcct_shared_memory *generic_comm_base =
+		(struct acpi_pcct_shared_memory *)pcc_ss_data->pcc_comm_addr;
+	unsigned int time_delta;
+
+	/*
+	 * For CMD_WRITE we know for a fact the caller should have checked
+	 * the channel before writing to PCC space
+	 */
+	if (cmd == CMD_READ) {
+		/*
+		 * If there are pending cpc_writes, then we stole the channel
+		 * before write completion, so first send a WRITE command to
+		 * platform
+		 */
+		if (pcc_ss_data->pending_pcc_write_cmd)
+			send_pcc_cmd(pcc_ss_id, CMD_WRITE);
+
+		ret = check_pcc_chan(pcc_ss_id, false);
+		if (ret)
+			goto end;
+	} else /* CMD_WRITE */
+		pcc_ss_data->pending_pcc_write_cmd = FALSE;
+
+	/*
+	 * Handle the Minimum Request Turnaround Time(MRTT)
+	 * "The minimum amount of time that OSPM must wait after the completion
+	 * of a command before issuing the next command, in microseconds"
+	 */
+	if (pcc_ss_data->pcc_mrtt) {
+		time_delta = ktime_us_delta(ktime_get(),
+					    pcc_ss_data->last_cmd_cmpl_time);
+		if (pcc_ss_data->pcc_mrtt > time_delta)
+			udelay(pcc_ss_data->pcc_mrtt - time_delta);
+	}
+
+	/*
+	 * Handle the non-zero Maximum Periodic Access Rate(MPAR)
+	 * "The maximum number of periodic requests that the subspace channel can
+	 * support, reported in commands per minute. 0 indicates no limitation."
+	 *
+	 * This parameter should be ideally zero or large enough so that it can
+	 * handle maximum number of requests that all the cores in the system can
+	 * collectively generate. If it is not, we will follow the spec and just
+	 * not send the request to the platform after hitting the MPAR limit in
+	 * any 60s window
+	 */
+	if (pcc_ss_data->pcc_mpar) {
+		if (pcc_ss_data->mpar_count == 0) {
+			time_delta = ktime_ms_delta(ktime_get(),
+						    pcc_ss_data->last_mpar_reset);
+			if ((time_delta < 60 * MSEC_PER_SEC) && pcc_ss_data->last_mpar_reset) {
+				pr_debug("PCC cmd for subspace %d not sent due to MPAR limit",
+					 pcc_ss_id);
+				ret = -EIO;
+				goto end;
+			}
+			pcc_ss_data->last_mpar_reset = ktime_get();
+			pcc_ss_data->mpar_count = pcc_ss_data->pcc_mpar;
+		}
+		pcc_ss_data->mpar_count--;
+	}
+
+	/* Write to the shared comm region. */
+	writew_relaxed(cmd, &generic_comm_base->command);
+
+	/* Flip CMD COMPLETE bit */
+	writew_relaxed(0, &generic_comm_base->status);
+
+	pcc_ss_data->platform_owns_pcc = true;
+
+	/* Ring doorbell */
+	ret = mbox_send_message(pcc_ss_data->pcc_channel, &cmd);
+	if (ret < 0) {
+		pr_err("Err sending PCC mbox message. ss: %d cmd:%d, ret:%d\n",
+		       pcc_ss_id, cmd, ret);
+		goto end;
+	}
+
+	/* wait for completion and check for PCC errro bit */
+	ret = check_pcc_chan(pcc_ss_id, true);
+
+	if (pcc_ss_data->pcc_mrtt)
+		pcc_ss_data->last_cmd_cmpl_time = ktime_get();
+
+	if (pcc_ss_data->pcc_channel->mbox->txdone_irq)
+		mbox_chan_txdone(pcc_ss_data->pcc_channel, ret);
+	else
+		mbox_client_txdone(pcc_ss_data->pcc_channel, ret);
+
+end:
+	if (cmd == CMD_WRITE) {
+		if (unlikely(ret)) {
+			for_each_possible_cpu(i) {
+				struct cpc_desc *desc = per_cpu(cpc_desc_ptr, i);
+				if (!desc)
+					continue;
+
+				if (desc->write_cmd_id == pcc_ss_data->pcc_write_cnt)
+					desc->write_cmd_status = ret;
+			}
+		}
+		pcc_ss_data->pcc_write_cnt++;
+		wake_up_all(&pcc_ss_data->pcc_write_wait_q);
+	}
+
+	return ret;
+}
+
+static void cppc_chan_tx_done(struct mbox_client *cl, void *msg, int ret)
+{
+	if (ret < 0)
+		pr_debug("TX did not complete: CMD sent:%x, ret:%d\n",
+				*(u16 *)msg, ret);
+	else
+		pr_debug("TX completed. CMD sent:%x, ret:%d\n",
+				*(u16 *)msg, ret);
+}
+
+static struct mbox_client cppc_mbox_cl = {
+	.tx_done = cppc_chan_tx_done,
+	.knows_txdone = true,
+};
+
+static int acpi_get_psd(struct cpc_desc *cpc_ptr, acpi_handle handle)
+{
+	int result = -EFAULT;
+	acpi_status status = AE_OK;
+	struct acpi_buffer buffer = {ACPI_ALLOCATE_BUFFER, NULL};
+	struct acpi_buffer format = {sizeof("NNNNN"), "NNNNN"};
+	struct acpi_buffer state = {0, NULL};
+	union acpi_object  *psd = NULL;
+	struct acpi_psd_package *pdomain;
+
+	status = acpi_evaluate_object_typed(handle, "_PSD", NULL,
+					    &buffer, ACPI_TYPE_PACKAGE);
+	if (status == AE_NOT_FOUND)	/* _PSD is optional */
+		return 0;
+	if (ACPI_FAILURE(status))
+		return -ENODEV;
+
+	psd = buffer.pointer;
+	if (!psd || psd->package.count != 1) {
+		pr_debug("Invalid _PSD data\n");
+		goto end;
+	}
+
+	pdomain = &(cpc_ptr->domain_info);
+
+	state.length = sizeof(struct acpi_psd_package);
+	state.pointer = pdomain;
+
+	status = acpi_extract_package(&(psd->package.elements[0]),
+		&format, &state);
+	if (ACPI_FAILURE(status)) {
+		pr_debug("Invalid _PSD data for CPU:%d\n", cpc_ptr->cpu_id);
+		goto end;
+	}
+
+	if (pdomain->num_entries != ACPI_PSD_REV0_ENTRIES) {
+		pr_debug("Unknown _PSD:num_entries for CPU:%d\n", cpc_ptr->cpu_id);
+		goto end;
+	}
+
+	if (pdomain->revision != ACPI_PSD_REV0_REVISION) {
+		pr_debug("Unknown _PSD:revision for CPU: %d\n", cpc_ptr->cpu_id);
+		goto end;
+	}
+
+	if (pdomain->coord_type != DOMAIN_COORD_TYPE_SW_ALL &&
+	    pdomain->coord_type != DOMAIN_COORD_TYPE_SW_ANY &&
+	    pdomain->coord_type != DOMAIN_COORD_TYPE_HW_ALL) {
+		pr_debug("Invalid _PSD:coord_type for CPU:%d\n", cpc_ptr->cpu_id);
+		goto end;
+	}
+
+	result = 0;
+end:
+	kfree(buffer.pointer);
+	return result;
+}
+
+/**
+ * acpi_get_psd_map - Map the CPUs in a common freq domain.
+ * @all_cpu_data: Ptrs to CPU specific CPPC data including PSD info.
+ *
+ *	Return: 0 for success or negative value for err.
+ */
+int acpi_get_psd_map(struct cppc_cpudata **all_cpu_data)
+{
+	int count_target;
+	int retval = 0;
+	unsigned int i, j;
+	cpumask_var_t covered_cpus;
+	struct cppc_cpudata *pr, *match_pr;
+	struct acpi_psd_package *pdomain;
+	struct acpi_psd_package *match_pdomain;
+	struct cpc_desc *cpc_ptr, *match_cpc_ptr;
+
+	if (!zalloc_cpumask_var(&covered_cpus, GFP_KERNEL))
+		return -ENOMEM;
+
+	/*
+	 * Now that we have _PSD data from all CPUs, let's setup P-state
+	 * domain info.
+	 */
+	for_each_possible_cpu(i) {
+		if (cpumask_test_cpu(i, covered_cpus))
+			continue;
+
+		pr = all_cpu_data[i];
+		cpc_ptr = per_cpu(cpc_desc_ptr, i);
+		if (!cpc_ptr) {
+			retval = -EFAULT;
+			goto err_ret;
+		}
+
+		pdomain = &(cpc_ptr->domain_info);
+		cpumask_set_cpu(i, pr->shared_cpu_map);
+		cpumask_set_cpu(i, covered_cpus);
+		if (pdomain->num_processors <= 1)
+			continue;
+
+		/* Validate the Domain info */
+		count_target = pdomain->num_processors;
+		if (pdomain->coord_type == DOMAIN_COORD_TYPE_SW_ALL)
+			pr->shared_type = CPUFREQ_SHARED_TYPE_ALL;
+		else if (pdomain->coord_type == DOMAIN_COORD_TYPE_HW_ALL)
+			pr->shared_type = CPUFREQ_SHARED_TYPE_HW;
+		else if (pdomain->coord_type == DOMAIN_COORD_TYPE_SW_ANY)
+			pr->shared_type = CPUFREQ_SHARED_TYPE_ANY;
+
+		for_each_possible_cpu(j) {
+			if (i == j)
+				continue;
+
+			match_cpc_ptr = per_cpu(cpc_desc_ptr, j);
+			if (!match_cpc_ptr) {
+				retval = -EFAULT;
+				goto err_ret;
+			}
+
+			match_pdomain = &(match_cpc_ptr->domain_info);
+			if (match_pdomain->domain != pdomain->domain)
+				continue;
+
+			/* Here i and j are in the same domain */
+			if (match_pdomain->num_processors != count_target) {
+				retval = -EFAULT;
+				goto err_ret;
+			}
+
+			if (pdomain->coord_type != match_pdomain->coord_type) {
+				retval = -EFAULT;
+				goto err_ret;
+			}
+
+			cpumask_set_cpu(j, covered_cpus);
+			cpumask_set_cpu(j, pr->shared_cpu_map);
+		}
+
+		for_each_cpu(j, pr->shared_cpu_map) {
+			if (i == j)
+				continue;
+
+			match_pr = all_cpu_data[j];
+			match_pr->shared_type = pr->shared_type;
+			cpumask_copy(match_pr->shared_cpu_map,
+				     pr->shared_cpu_map);
+		}
+	}
+	goto out;
+
+err_ret:
+	for_each_possible_cpu(i) {
+		pr = all_cpu_data[i];
+
+		/* Assume no coordination on any error parsing domain info */
+		cpumask_clear(pr->shared_cpu_map);
+		cpumask_set_cpu(i, pr->shared_cpu_map);
+		pr->shared_type = CPUFREQ_SHARED_TYPE_ALL;
+	}
+out:
+	free_cpumask_var(covered_cpus);
+	return retval;
+}
+EXPORT_SYMBOL_GPL(acpi_get_psd_map);
+
+static int register_pcc_channel(int pcc_ss_idx)
+{
+	struct acpi_pcct_hw_reduced *cppc_ss;
+	u64 usecs_lat;
+
+	if (pcc_ss_idx >= 0) {
+		pcc_data[pcc_ss_idx]->pcc_channel =
+			pcc_mbox_request_channel(&cppc_mbox_cl,	pcc_ss_idx);
+
+		if (IS_ERR(pcc_data[pcc_ss_idx]->pcc_channel)) {
+			pr_err("Failed to find PCC channel for subspace %d\n",
+			       pcc_ss_idx);
+			return -ENODEV;
+		}
+
+		/*
+		 * The PCC mailbox controller driver should
+		 * have parsed the PCCT (global table of all
+		 * PCC channels) and stored pointers to the
+		 * subspace communication region in con_priv.
+		 */
+		cppc_ss = (pcc_data[pcc_ss_idx]->pcc_channel)->con_priv;
+
+		if (!cppc_ss) {
+			pr_err("No PCC subspace found for %d CPPC\n",
+			       pcc_ss_idx);
+			return -ENODEV;
+		}
+
+		/*
+		 * cppc_ss->latency is just a Nominal value. In reality
+		 * the remote processor could be much slower to reply.
+		 * So add an arbitrary amount of wait on top of Nominal.
+		 */
+		usecs_lat = NUM_RETRIES * cppc_ss->latency;
+		pcc_data[pcc_ss_idx]->deadline_us = usecs_lat;
+		pcc_data[pcc_ss_idx]->pcc_mrtt = cppc_ss->min_turnaround_time;
+		pcc_data[pcc_ss_idx]->pcc_mpar = cppc_ss->max_access_rate;
+		pcc_data[pcc_ss_idx]->pcc_nominal = cppc_ss->latency;
+
+		pcc_data[pcc_ss_idx]->pcc_comm_addr =
+			acpi_os_ioremap(cppc_ss->base_address, cppc_ss->length);
+		if (!pcc_data[pcc_ss_idx]->pcc_comm_addr) {
+			pr_err("Failed to ioremap PCC comm region mem for %d\n",
+			       pcc_ss_idx);
+			return -ENOMEM;
+		}
+
+		/* Set flag so that we don't come here for each CPU. */
+		pcc_data[pcc_ss_idx]->pcc_channel_acquired = true;
+	}
+
+	return 0;
+}
+
+/**
+ * cpc_ffh_supported() - check if FFH reading supported
+ *
+ * Check if the architecture has support for functional fixed hardware
+ * read/write capability.
+ *
+ * Return: true for supported, false for not supported
+ */
+bool __weak cpc_ffh_supported(void)
+{
+	return false;
+}
+
+/**
+ * pcc_data_alloc() - Allocate the pcc_data memory for pcc subspace
+ *
+ * Check and allocate the cppc_pcc_data memory.
+ * In some processor configurations it is possible that same subspace
+ * is shared between multiple CPUs. This is seen especially in CPUs
+ * with hardware multi-threading support.
+ *
+ * Return: 0 for success, errno for failure
+ */
+static int pcc_data_alloc(int pcc_ss_id)
+{
+	if (pcc_ss_id < 0 || pcc_ss_id >= MAX_PCC_SUBSPACES)
+		return -EINVAL;
+
+	if (pcc_data[pcc_ss_id]) {
+		pcc_data[pcc_ss_id]->refcount++;
+	} else {
+		pcc_data[pcc_ss_id] = kzalloc(sizeof(struct cppc_pcc_data),
+					      GFP_KERNEL);
+		if (!pcc_data[pcc_ss_id])
+			return -ENOMEM;
+		pcc_data[pcc_ss_id]->refcount++;
+	}
+
+	return 0;
+}
+
+/*
+ * An example CPC table looks like the following.
+ *
+ *	Name(_CPC, Package()
+ *			{
+ *			17,
+ *			NumEntries
+ *			1,
+ *			// Revision
+ *			ResourceTemplate(){Register(PCC, 32, 0, 0x120, 2)},
+ *			// Highest Performance
+ *			ResourceTemplate(){Register(PCC, 32, 0, 0x124, 2)},
+ *			// Nominal Performance
+ *			ResourceTemplate(){Register(PCC, 32, 0, 0x128, 2)},
+ *			// Lowest Nonlinear Performance
+ *			ResourceTemplate(){Register(PCC, 32, 0, 0x12C, 2)},
+ *			// Lowest Performance
+ *			ResourceTemplate(){Register(PCC, 32, 0, 0x130, 2)},
+ *			// Guaranteed Performance Register
+ *			ResourceTemplate(){Register(PCC, 32, 0, 0x110, 2)},
+ *			// Desired Performance Register
+ *			ResourceTemplate(){Register(SystemMemory, 0, 0, 0, 0)},
+ *			..
+ *			..
+ *			..
+ *
+ *		}
+ * Each Register() encodes how to access that specific register.
+ * e.g. a sample PCC entry has the following encoding:
+ *
+ *	Register (
+ *		PCC,
+ *		AddressSpaceKeyword
+ *		8,
+ *		//RegisterBitWidth
+ *		8,
+ *		//RegisterBitOffset
+ *		0x30,
+ *		//RegisterAddress
+ *		9
+ *		//AccessSize (subspace ID)
+ *		0
+ *		)
+ *	}
+ */
+
+/**
+ * acpi_cppc_processor_probe - Search for per CPU _CPC objects.
+ * @pr: Ptr to acpi_processor containing this CPU's logical ID.
+ *
+ *	Return: 0 for success or negative value for err.
+ */
+int acpi_cppc_processor_probe(struct acpi_processor *pr)
+{
+	struct acpi_buffer output = {ACPI_ALLOCATE_BUFFER, NULL};
+	union acpi_object *out_obj, *cpc_obj;
+	struct cpc_desc *cpc_ptr;
+	struct cpc_reg *gas_t;
+	struct device *cpu_dev;
+	acpi_handle handle = pr->handle;
+	unsigned int num_ent, i, cpc_rev;
+	int pcc_subspace_id = -1;
+	acpi_status status;
+	int ret = -EFAULT;
+
+	/* Parse the ACPI _CPC table for this CPU. */
+	status = acpi_evaluate_object_typed(handle, "_CPC", NULL, &output,
+			ACPI_TYPE_PACKAGE);
+	if (ACPI_FAILURE(status)) {
+		ret = -ENODEV;
+		goto out_buf_free;
+	}
+
+	out_obj = (union acpi_object *) output.pointer;
+
+	cpc_ptr = kzalloc(sizeof(struct cpc_desc), GFP_KERNEL);
+	if (!cpc_ptr) {
+		ret = -ENOMEM;
+		goto out_buf_free;
+	}
+
+	/* First entry is NumEntries. */
+	cpc_obj = &out_obj->package.elements[0];
+	if (cpc_obj->type == ACPI_TYPE_INTEGER)	{
+		num_ent = cpc_obj->integer.value;
+		if (num_ent <= 1) {
+			pr_debug("Unexpected _CPC NumEntries value (%d) for CPU:%d\n",
+				 num_ent, pr->id);
+			goto out_free;
+		}
+	} else {
+		pr_debug("Unexpected entry type(%d) for NumEntries\n",
+				cpc_obj->type);
+		goto out_free;
+	}
+
+	/* Second entry should be revision. */
+	cpc_obj = &out_obj->package.elements[1];
+	if (cpc_obj->type == ACPI_TYPE_INTEGER)	{
+		cpc_rev = cpc_obj->integer.value;
+	} else {
+		pr_debug("Unexpected entry type(%d) for Revision\n",
+				cpc_obj->type);
+		goto out_free;
+	}
+
+	if (cpc_rev < CPPC_V2_REV) {
+		pr_debug("Unsupported _CPC Revision (%d) for CPU:%d\n", cpc_rev,
+			 pr->id);
+		goto out_free;
+	}
+
+	/*
+	 * Disregard _CPC if the number of entries in the return pachage is not
+	 * as expected, but support future revisions being proper supersets of
+	 * the v3 and only causing more entries to be returned by _CPC.
+	 */
+	if ((cpc_rev == CPPC_V2_REV && num_ent != CPPC_V2_NUM_ENT) ||
+	    (cpc_rev == CPPC_V3_REV && num_ent != CPPC_V3_NUM_ENT) ||
+	    (cpc_rev > CPPC_V3_REV && num_ent <= CPPC_V3_NUM_ENT)) {
+		pr_debug("Unexpected number of _CPC return package entries (%d) for CPU:%d\n",
+			 num_ent, pr->id);
+		goto out_free;
+	}
+	if (cpc_rev > CPPC_V3_REV) {
+		num_ent = CPPC_V3_NUM_ENT;
+		cpc_rev = CPPC_V3_REV;
+	}
+
+	cpc_ptr->num_entries = num_ent;
+	cpc_ptr->version = cpc_rev;
+
+	/* Iterate through remaining entries in _CPC */
+	for (i = 2; i < num_ent; i++) {
+		cpc_obj = &out_obj->package.elements[i];
+
+		if (cpc_obj->type == ACPI_TYPE_INTEGER)	{
+			cpc_ptr->cpc_regs[i-2].type = ACPI_TYPE_INTEGER;
+			cpc_ptr->cpc_regs[i-2].cpc_entry.int_value = cpc_obj->integer.value;
+		} else if (cpc_obj->type == ACPI_TYPE_BUFFER) {
+			gas_t = (struct cpc_reg *)
+				cpc_obj->buffer.pointer;
+
+			/*
+			 * The PCC Subspace index is encoded inside
+			 * the CPC table entries. The same PCC index
+			 * will be used for all the PCC entries,
+			 * so extract it only once.
+			 */
+			if (gas_t->space_id == ACPI_ADR_SPACE_PLATFORM_COMM) {
+				if (pcc_subspace_id < 0) {
+					pcc_subspace_id = gas_t->access_width;
+					if (pcc_data_alloc(pcc_subspace_id))
+						goto out_free;
+				} else if (pcc_subspace_id != gas_t->access_width) {
+					pr_debug("Mismatched PCC ids.\n");
+					goto out_free;
+				}
+			} else if (gas_t->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY) {
+				if (gas_t->address) {
+					void __iomem *addr;
+
+					addr = ioremap(gas_t->address, gas_t->bit_width/8);
+					if (!addr)
+						goto out_free;
+					cpc_ptr->cpc_regs[i-2].sys_mem_vaddr = addr;
+				}
+			} else {
+				if (gas_t->space_id != ACPI_ADR_SPACE_FIXED_HARDWARE || !cpc_ffh_supported()) {
+					/* Support only PCC ,SYS MEM and FFH type regs */
+					pr_debug("Unsupported register type: %d\n", gas_t->space_id);
+					goto out_free;
+				}
+			}
+
+			cpc_ptr->cpc_regs[i-2].type = ACPI_TYPE_BUFFER;
+			memcpy(&cpc_ptr->cpc_regs[i-2].cpc_entry.reg, gas_t, sizeof(*gas_t));
+		} else {
+			pr_debug("Err in entry:%d in CPC table of CPU:%d \n", i, pr->id);
+			goto out_free;
+		}
+	}
+	per_cpu(cpu_pcc_subspace_idx, pr->id) = pcc_subspace_id;
+
+	/*
+	 * Initialize the remaining cpc_regs as unsupported.
+	 * Example: In case FW exposes CPPC v2, the below loop will initialize
+	 * LOWEST_FREQ and NOMINAL_FREQ regs as unsupported
+	 */
+	for (i = num_ent - 2; i < MAX_CPC_REG_ENT; i++) {
+		cpc_ptr->cpc_regs[i].type = ACPI_TYPE_INTEGER;
+		cpc_ptr->cpc_regs[i].cpc_entry.int_value = 0;
+	}
+
+
+	/* Store CPU Logical ID */
+	cpc_ptr->cpu_id = pr->id;
+
+	/* Parse PSD data for this CPU */
+	ret = acpi_get_psd(cpc_ptr, handle);
+	if (ret)
+		goto out_free;
+
+	/* Register PCC channel once for all PCC subspace ID. */
+	if (pcc_subspace_id >= 0 && !pcc_data[pcc_subspace_id]->pcc_channel_acquired) {
+		ret = register_pcc_channel(pcc_subspace_id);
+		if (ret)
+			goto out_free;
+
+		init_rwsem(&pcc_data[pcc_subspace_id]->pcc_lock);
+		init_waitqueue_head(&pcc_data[pcc_subspace_id]->pcc_write_wait_q);
+	}
+
+	/* Everything looks okay */
+	pr_debug("Parsed CPC struct for CPU: %d\n", pr->id);
+
+	/* Add per logical CPU nodes for reading its feedback counters. */
+	cpu_dev = get_cpu_device(pr->id);
+	if (!cpu_dev) {
+		ret = -EINVAL;
+		goto out_free;
+	}
+
+	/* Plug PSD data into this CPU's CPC descriptor. */
+	per_cpu(cpc_desc_ptr, pr->id) = cpc_ptr;
+
+	ret = kobject_init_and_add(&cpc_ptr->kobj, &cppc_ktype, &cpu_dev->kobj,
+			"acpi_cppc");
+	if (ret) {
+		per_cpu(cpc_desc_ptr, pr->id) = NULL;
+		kobject_put(&cpc_ptr->kobj);
+		goto out_free;
+	}
+
+	kfree(output.pointer);
+	return 0;
+
+out_free:
+	/* Free all the mapped sys mem areas for this CPU */
+	for (i = 2; i < cpc_ptr->num_entries; i++) {
+		void __iomem *addr = cpc_ptr->cpc_regs[i-2].sys_mem_vaddr;
+
+		if (addr)
+			iounmap(addr);
+	}
+	kfree(cpc_ptr);
+
+out_buf_free:
+	kfree(output.pointer);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(acpi_cppc_processor_probe);
+
+/**
+ * acpi_cppc_processor_exit - Cleanup CPC structs.
+ * @pr: Ptr to acpi_processor containing this CPU's logical ID.
+ *
+ * Return: Void
+ */
+void acpi_cppc_processor_exit(struct acpi_processor *pr)
+{
+	struct cpc_desc *cpc_ptr;
+	unsigned int i;
+	void __iomem *addr;
+	int pcc_ss_id = per_cpu(cpu_pcc_subspace_idx, pr->id);
+
+	if (pcc_ss_id >=0 && pcc_data[pcc_ss_id]) {
+		if (pcc_data[pcc_ss_id]->pcc_channel_acquired) {
+			pcc_data[pcc_ss_id]->refcount--;
+			if (!pcc_data[pcc_ss_id]->refcount) {
+				pcc_mbox_free_channel(pcc_data[pcc_ss_id]->pcc_channel);
+				kfree(pcc_data[pcc_ss_id]);
+				pcc_data[pcc_ss_id] = NULL;
+			}
+		}
+	}
+
+	cpc_ptr = per_cpu(cpc_desc_ptr, pr->id);
+	if (!cpc_ptr)
+		return;
+
+	/* Free all the mapped sys mem areas for this CPU */
+	for (i = 2; i < cpc_ptr->num_entries; i++) {
+		addr = cpc_ptr->cpc_regs[i-2].sys_mem_vaddr;
+		if (addr)
+			iounmap(addr);
+	}
+
+	kobject_put(&cpc_ptr->kobj);
+	kfree(cpc_ptr);
+}
+EXPORT_SYMBOL_GPL(acpi_cppc_processor_exit);
+
+/**
+ * cpc_read_ffh() - Read FFH register
+ * @cpunum:	CPU number to read
+ * @reg:	cppc register information
+ * @val:	place holder for return value
+ *
+ * Read bit_width bits from a specified address and bit_offset
+ *
+ * Return: 0 for success and error code
+ */
+int __weak cpc_read_ffh(int cpunum, struct cpc_reg *reg, u64 *val)
+{
+	return -ENOTSUPP;
+}
+
+/**
+ * cpc_write_ffh() - Write FFH register
+ * @cpunum:	CPU number to write
+ * @reg:	cppc register information
+ * @val:	value to write
+ *
+ * Write value of bit_width bits to a specified address and bit_offset
+ *
+ * Return: 0 for success and error code
+ */
+int __weak cpc_write_ffh(int cpunum, struct cpc_reg *reg, u64 val)
+{
+	return -ENOTSUPP;
+}
+
+/*
+ * Since cpc_read and cpc_write are called while holding pcc_lock, it should be
+ * as fast as possible. We have already mapped the PCC subspace during init, so
+ * we can directly write to it.
+ */
+
+static int cpc_read(int cpu, struct cpc_register_resource *reg_res, u64 *val)
+{
+	int ret_val = 0;
+	void __iomem *vaddr = 0;
+	int pcc_ss_id = per_cpu(cpu_pcc_subspace_idx, cpu);
+	struct cpc_reg *reg = &reg_res->cpc_entry.reg;
+
+	if (reg_res->type == ACPI_TYPE_INTEGER) {
+		*val = reg_res->cpc_entry.int_value;
+		return ret_val;
+	}
+
+	*val = 0;
+	if (reg->space_id == ACPI_ADR_SPACE_PLATFORM_COMM && pcc_ss_id >= 0)
+		vaddr = GET_PCC_VADDR(reg->address, pcc_ss_id);
+	else if (reg->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY)
+		vaddr = reg_res->sys_mem_vaddr;
+	else if (reg->space_id == ACPI_ADR_SPACE_FIXED_HARDWARE)
+		return cpc_read_ffh(cpu, reg, val);
+	else
+		return acpi_os_read_memory((acpi_physical_address)reg->address,
+				val, reg->bit_width);
+
+	switch (reg->bit_width) {
+		case 8:
+			*val = readb_relaxed(vaddr);
+			break;
+		case 16:
+			*val = readw_relaxed(vaddr);
+			break;
+		case 32:
+			*val = readl_relaxed(vaddr);
+			break;
+		case 64:
+			*val = readq_relaxed(vaddr);
+			break;
+		default:
+			pr_debug("Error: Cannot read %u bit width from PCC for ss: %d\n",
+				 reg->bit_width, pcc_ss_id);
+			ret_val = -EFAULT;
+	}
+
+	return ret_val;
+}
+
+static int cpc_write(int cpu, struct cpc_register_resource *reg_res, u64 val)
+{
+	int ret_val = 0;
+	void __iomem *vaddr = 0;
+	int pcc_ss_id = per_cpu(cpu_pcc_subspace_idx, cpu);
+	struct cpc_reg *reg = &reg_res->cpc_entry.reg;
+
+	if (reg->space_id == ACPI_ADR_SPACE_PLATFORM_COMM && pcc_ss_id >= 0)
+		vaddr = GET_PCC_VADDR(reg->address, pcc_ss_id);
+	else if (reg->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY)
+		vaddr = reg_res->sys_mem_vaddr;
+	else if (reg->space_id == ACPI_ADR_SPACE_FIXED_HARDWARE)
+		return cpc_write_ffh(cpu, reg, val);
+	else
+		return acpi_os_write_memory((acpi_physical_address)reg->address,
+				val, reg->bit_width);
+
+	switch (reg->bit_width) {
+		case 8:
+			writeb_relaxed(val, vaddr);
+			break;
+		case 16:
+			writew_relaxed(val, vaddr);
+			break;
+		case 32:
+			writel_relaxed(val, vaddr);
+			break;
+		case 64:
+			writeq_relaxed(val, vaddr);
+			break;
+		default:
+			pr_debug("Error: Cannot write %u bit width to PCC for ss: %d\n",
+				 reg->bit_width, pcc_ss_id);
+			ret_val = -EFAULT;
+			break;
+	}
+
+	return ret_val;
+}
+
+/**
+ * cppc_get_desired_perf - Get the value of desired performance register.
+ * @cpunum: CPU from which to get desired performance.
+ * @desired_perf: address of a variable to store the returned desired performance
+ *
+ * Return: 0 for success, -EIO otherwise.
+ */
+int cppc_get_desired_perf(int cpunum, u64 *desired_perf)
+{
+	struct cpc_desc *cpc_desc = per_cpu(cpc_desc_ptr, cpunum);
+	int pcc_ss_id = per_cpu(cpu_pcc_subspace_idx, cpunum);
+	struct cpc_register_resource *desired_reg;
+	struct cppc_pcc_data *pcc_ss_data = NULL;
+
+	desired_reg = &cpc_desc->cpc_regs[DESIRED_PERF];
+
+	if (CPC_IN_PCC(desired_reg)) {
+		int ret = 0;
+
+		if (pcc_ss_id < 0)
+			return -EIO;
+
+		pcc_ss_data = pcc_data[pcc_ss_id];
+
+		down_write(&pcc_ss_data->pcc_lock);
+
+		if (send_pcc_cmd(pcc_ss_id, CMD_READ) >= 0)
+			cpc_read(cpunum, desired_reg, desired_perf);
+		else
+			ret = -EIO;
+
+		up_write(&pcc_ss_data->pcc_lock);
+
+		return ret;
+	}
+
+	cpc_read(cpunum, desired_reg, desired_perf);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(cppc_get_desired_perf);
+
+/**
+ * cppc_get_perf_caps - Get a CPU's performance capabilities.
+ * @cpunum: CPU from which to get capabilities info.
+ * @perf_caps: ptr to cppc_perf_caps. See cppc_acpi.h
+ *
+ * Return: 0 for success with perf_caps populated else -ERRNO.
+ */
+int cppc_get_perf_caps(int cpunum, struct cppc_perf_caps *perf_caps)
+{
+	struct cpc_desc *cpc_desc = per_cpu(cpc_desc_ptr, cpunum);
+	struct cpc_register_resource *highest_reg, *lowest_reg,
+		*lowest_non_linear_reg, *nominal_reg, *guaranteed_reg,
+		*low_freq_reg = NULL, *nom_freq_reg = NULL;
+	u64 high, low, guaranteed, nom, min_nonlinear, low_f = 0, nom_f = 0;
+	int pcc_ss_id = per_cpu(cpu_pcc_subspace_idx, cpunum);
+	struct cppc_pcc_data *pcc_ss_data = NULL;
+	int ret = 0, regs_in_pcc = 0;
+
+	if (!cpc_desc) {
+		pr_debug("No CPC descriptor for CPU:%d\n", cpunum);
+		return -ENODEV;
+	}
+
+	highest_reg = &cpc_desc->cpc_regs[HIGHEST_PERF];
+	lowest_reg = &cpc_desc->cpc_regs[LOWEST_PERF];
+	lowest_non_linear_reg = &cpc_desc->cpc_regs[LOW_NON_LINEAR_PERF];
+	nominal_reg = &cpc_desc->cpc_regs[NOMINAL_PERF];
+	low_freq_reg = &cpc_desc->cpc_regs[LOWEST_FREQ];
+	nom_freq_reg = &cpc_desc->cpc_regs[NOMINAL_FREQ];
+	guaranteed_reg = &cpc_desc->cpc_regs[GUARANTEED_PERF];
+
+	/* Are any of the regs PCC ?*/
+	if (CPC_IN_PCC(highest_reg) || CPC_IN_PCC(lowest_reg) ||
+		CPC_IN_PCC(lowest_non_linear_reg) || CPC_IN_PCC(nominal_reg) ||
+		CPC_IN_PCC(low_freq_reg) || CPC_IN_PCC(nom_freq_reg)) {
+		if (pcc_ss_id < 0) {
+			pr_debug("Invalid pcc_ss_id\n");
+			return -ENODEV;
+		}
+		pcc_ss_data = pcc_data[pcc_ss_id];
+		regs_in_pcc = 1;
+		down_write(&pcc_ss_data->pcc_lock);
+		/* Ring doorbell once to update PCC subspace */
+		if (send_pcc_cmd(pcc_ss_id, CMD_READ) < 0) {
+			ret = -EIO;
+			goto out_err;
+		}
+	}
+
+	cpc_read(cpunum, highest_reg, &high);
+	perf_caps->highest_perf = high;
+
+	cpc_read(cpunum, lowest_reg, &low);
+	perf_caps->lowest_perf = low;
+
+	cpc_read(cpunum, nominal_reg, &nom);
+	perf_caps->nominal_perf = nom;
+
+	if (guaranteed_reg->type != ACPI_TYPE_BUFFER  ||
+	    IS_NULL_REG(&guaranteed_reg->cpc_entry.reg)) {
+		perf_caps->guaranteed_perf = 0;
+	} else {
+		cpc_read(cpunum, guaranteed_reg, &guaranteed);
+		perf_caps->guaranteed_perf = guaranteed;
+	}
+
+	cpc_read(cpunum, lowest_non_linear_reg, &min_nonlinear);
+	perf_caps->lowest_nonlinear_perf = min_nonlinear;
+
+	if (!high || !low || !nom || !min_nonlinear)
+		ret = -EFAULT;
+
+	/* Read optional lowest and nominal frequencies if present */
+	if (CPC_SUPPORTED(low_freq_reg))
+		cpc_read(cpunum, low_freq_reg, &low_f);
+
+	if (CPC_SUPPORTED(nom_freq_reg))
+		cpc_read(cpunum, nom_freq_reg, &nom_f);
+
+	perf_caps->lowest_freq = low_f;
+	perf_caps->nominal_freq = nom_f;
+
+
+out_err:
+	if (regs_in_pcc)
+		up_write(&pcc_ss_data->pcc_lock);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(cppc_get_perf_caps);
+
+/**
+ * cppc_get_perf_ctrs - Read a CPU's performance feedback counters.
+ * @cpunum: CPU from which to read counters.
+ * @perf_fb_ctrs: ptr to cppc_perf_fb_ctrs. See cppc_acpi.h
+ *
+ * Return: 0 for success with perf_fb_ctrs populated else -ERRNO.
+ */
+int cppc_get_perf_ctrs(int cpunum, struct cppc_perf_fb_ctrs *perf_fb_ctrs)
+{
+	struct cpc_desc *cpc_desc = per_cpu(cpc_desc_ptr, cpunum);
+	struct cpc_register_resource *delivered_reg, *reference_reg,
+		*ref_perf_reg, *ctr_wrap_reg;
+	int pcc_ss_id = per_cpu(cpu_pcc_subspace_idx, cpunum);
+	struct cppc_pcc_data *pcc_ss_data = NULL;
+	u64 delivered, reference, ref_perf, ctr_wrap_time;
+	int ret = 0, regs_in_pcc = 0;
+
+	if (!cpc_desc) {
+		pr_debug("No CPC descriptor for CPU:%d\n", cpunum);
+		return -ENODEV;
+	}
+
+	delivered_reg = &cpc_desc->cpc_regs[DELIVERED_CTR];
+	reference_reg = &cpc_desc->cpc_regs[REFERENCE_CTR];
+	ref_perf_reg = &cpc_desc->cpc_regs[REFERENCE_PERF];
+	ctr_wrap_reg = &cpc_desc->cpc_regs[CTR_WRAP_TIME];
+
+	/*
+	 * If reference perf register is not supported then we should
+	 * use the nominal perf value
+	 */
+	if (!CPC_SUPPORTED(ref_perf_reg))
+		ref_perf_reg = &cpc_desc->cpc_regs[NOMINAL_PERF];
+
+	/* Are any of the regs PCC ?*/
+	if (CPC_IN_PCC(delivered_reg) || CPC_IN_PCC(reference_reg) ||
+		CPC_IN_PCC(ctr_wrap_reg) || CPC_IN_PCC(ref_perf_reg)) {
+		if (pcc_ss_id < 0) {
+			pr_debug("Invalid pcc_ss_id\n");
+			return -ENODEV;
+		}
+		pcc_ss_data = pcc_data[pcc_ss_id];
+		down_write(&pcc_ss_data->pcc_lock);
+		regs_in_pcc = 1;
+		/* Ring doorbell once to update PCC subspace */
+		if (send_pcc_cmd(pcc_ss_id, CMD_READ) < 0) {
+			ret = -EIO;
+			goto out_err;
+		}
+	}
+
+	cpc_read(cpunum, delivered_reg, &delivered);
+	cpc_read(cpunum, reference_reg, &reference);
+	cpc_read(cpunum, ref_perf_reg, &ref_perf);
+
+	/*
+	 * Per spec, if ctr_wrap_time optional register is unsupported, then the
+	 * performance counters are assumed to never wrap during the lifetime of
+	 * platform
+	 */
+	ctr_wrap_time = (u64)(~((u64)0));
+	if (CPC_SUPPORTED(ctr_wrap_reg))
+		cpc_read(cpunum, ctr_wrap_reg, &ctr_wrap_time);
+
+	if (!delivered || !reference ||	!ref_perf) {
+		ret = -EFAULT;
+		goto out_err;
+	}
+
+	perf_fb_ctrs->delivered = delivered;
+	perf_fb_ctrs->reference = reference;
+	perf_fb_ctrs->reference_perf = ref_perf;
+	perf_fb_ctrs->wraparound_time = ctr_wrap_time;
+out_err:
+	if (regs_in_pcc)
+		up_write(&pcc_ss_data->pcc_lock);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(cppc_get_perf_ctrs);
+
+/**
+ * cppc_set_perf - Set a CPU's performance controls.
+ * @cpu: CPU for which to set performance controls.
+ * @perf_ctrls: ptr to cppc_perf_ctrls. See cppc_acpi.h
+ *
+ * Return: 0 for success, -ERRNO otherwise.
+ */
+int cppc_set_perf(int cpu, struct cppc_perf_ctrls *perf_ctrls)
+{
+	struct cpc_desc *cpc_desc = per_cpu(cpc_desc_ptr, cpu);
+	struct cpc_register_resource *desired_reg;
+	int pcc_ss_id = per_cpu(cpu_pcc_subspace_idx, cpu);
+	struct cppc_pcc_data *pcc_ss_data = NULL;
+	int ret = 0;
+
+	if (!cpc_desc) {
+		pr_debug("No CPC descriptor for CPU:%d\n", cpu);
+		return -ENODEV;
+	}
+
+	desired_reg = &cpc_desc->cpc_regs[DESIRED_PERF];
+
+	/*
+	 * This is Phase-I where we want to write to CPC registers
+	 * -> We want all CPUs to be able to execute this phase in parallel
+	 *
+	 * Since read_lock can be acquired by multiple CPUs simultaneously we
+	 * achieve that goal here
+	 */
+	if (CPC_IN_PCC(desired_reg)) {
+		if (pcc_ss_id < 0) {
+			pr_debug("Invalid pcc_ss_id\n");
+			return -ENODEV;
+		}
+		pcc_ss_data = pcc_data[pcc_ss_id];
+		down_read(&pcc_ss_data->pcc_lock); /* BEGIN Phase-I */
+		if (pcc_ss_data->platform_owns_pcc) {
+			ret = check_pcc_chan(pcc_ss_id, false);
+			if (ret) {
+				up_read(&pcc_ss_data->pcc_lock);
+				return ret;
+			}
+		}
+		/*
+		 * Update the pending_write to make sure a PCC CMD_READ will not
+		 * arrive and steal the channel during the switch to write lock
+		 */
+		pcc_ss_data->pending_pcc_write_cmd = true;
+		cpc_desc->write_cmd_id = pcc_ss_data->pcc_write_cnt;
+		cpc_desc->write_cmd_status = 0;
+	}
+
+	/*
+	 * Skip writing MIN/MAX until Linux knows how to come up with
+	 * useful values.
+	 */
+	cpc_write(cpu, desired_reg, perf_ctrls->desired_perf);
+
+	if (CPC_IN_PCC(desired_reg))
+		up_read(&pcc_ss_data->pcc_lock);	/* END Phase-I */
+	/*
+	 * This is Phase-II where we transfer the ownership of PCC to Platform
+	 *
+	 * Short Summary: Basically if we think of a group of cppc_set_perf
+	 * requests that happened in short overlapping interval. The last CPU to
+	 * come out of Phase-I will enter Phase-II and ring the doorbell.
+	 *
+	 * We have the following requirements for Phase-II:
+	 *     1. We want to execute Phase-II only when there are no CPUs
+	 * currently executing in Phase-I
+	 *     2. Once we start Phase-II we want to avoid all other CPUs from
+	 * entering Phase-I.
+	 *     3. We want only one CPU among all those who went through Phase-I
+	 * to run phase-II
+	 *
+	 * If write_trylock fails to get the lock and doesn't transfer the
+	 * PCC ownership to the platform, then one of the following will be TRUE
+	 *     1. There is at-least one CPU in Phase-I which will later execute
+	 * write_trylock, so the CPUs in Phase-I will be responsible for
+	 * executing the Phase-II.
+	 *     2. Some other CPU has beaten this CPU to successfully execute the
+	 * write_trylock and has already acquired the write_lock. We know for a
+	 * fact it (other CPU acquiring the write_lock) couldn't have happened
+	 * before this CPU's Phase-I as we held the read_lock.
+	 *     3. Some other CPU executing pcc CMD_READ has stolen the
+	 * down_write, in which case, send_pcc_cmd will check for pending
+	 * CMD_WRITE commands by checking the pending_pcc_write_cmd.
+	 * So this CPU can be certain that its request will be delivered
+	 *    So in all cases, this CPU knows that its request will be delivered
+	 * by another CPU and can return
+	 *
+	 * After getting the down_write we still need to check for
+	 * pending_pcc_write_cmd to take care of the following scenario
+	 *    The thread running this code could be scheduled out between
+	 * Phase-I and Phase-II. Before it is scheduled back on, another CPU
+	 * could have delivered the request to Platform by triggering the
+	 * doorbell and transferred the ownership of PCC to platform. So this
+	 * avoids triggering an unnecessary doorbell and more importantly before
+	 * triggering the doorbell it makes sure that the PCC channel ownership
+	 * is still with OSPM.
+	 *   pending_pcc_write_cmd can also be cleared by a different CPU, if
+	 * there was a pcc CMD_READ waiting on down_write and it steals the lock
+	 * before the pcc CMD_WRITE is completed. pcc_send_cmd checks for this
+	 * case during a CMD_READ and if there are pending writes it delivers
+	 * the write command before servicing the read command
+	 */
+	if (CPC_IN_PCC(desired_reg)) {
+		if (down_write_trylock(&pcc_ss_data->pcc_lock)) {/* BEGIN Phase-II */
+			/* Update only if there are pending write commands */
+			if (pcc_ss_data->pending_pcc_write_cmd)
+				send_pcc_cmd(pcc_ss_id, CMD_WRITE);
+			up_write(&pcc_ss_data->pcc_lock);	/* END Phase-II */
+		} else
+			/* Wait until pcc_write_cnt is updated by send_pcc_cmd */
+			wait_event(pcc_ss_data->pcc_write_wait_q,
+				   cpc_desc->write_cmd_id != pcc_ss_data->pcc_write_cnt);
+
+		/* send_pcc_cmd updates the status in case of failure */
+		ret = cpc_desc->write_cmd_status;
+	}
+	return ret;
+}
+EXPORT_SYMBOL_GPL(cppc_set_perf);
+
+/**
+ * cppc_get_transition_latency - returns frequency transition latency in ns
+ *
+ * ACPI CPPC does not explicitly specifiy how a platform can specify the
+ * transition latency for perfromance change requests. The closest we have
+ * is the timing information from the PCCT tables which provides the info
+ * on the number and frequency of PCC commands the platform can handle.
+ */
+unsigned int cppc_get_transition_latency(int cpu_num)
+{
+	/*
+	 * Expected transition latency is based on the PCCT timing values
+	 * Below are definition from ACPI spec:
+	 * pcc_nominal- Expected latency to process a command, in microseconds
+	 * pcc_mpar   - The maximum number of periodic requests that the subspace
+	 *              channel can support, reported in commands per minute. 0
+	 *              indicates no limitation.
+	 * pcc_mrtt   - The minimum amount of time that OSPM must wait after the
+	 *              completion of a command before issuing the next command,
+	 *              in microseconds.
+	 */
+	unsigned int latency_ns = 0;
+	struct cpc_desc *cpc_desc;
+	struct cpc_register_resource *desired_reg;
+	int pcc_ss_id = per_cpu(cpu_pcc_subspace_idx, cpu_num);
+	struct cppc_pcc_data *pcc_ss_data;
+
+	cpc_desc = per_cpu(cpc_desc_ptr, cpu_num);
+	if (!cpc_desc)
+		return CPUFREQ_ETERNAL;
+
+	desired_reg = &cpc_desc->cpc_regs[DESIRED_PERF];
+	if (!CPC_IN_PCC(desired_reg))
+		return CPUFREQ_ETERNAL;
+
+	if (pcc_ss_id < 0)
+		return CPUFREQ_ETERNAL;
+
+	pcc_ss_data = pcc_data[pcc_ss_id];
+	if (pcc_ss_data->pcc_mpar)
+		latency_ns = 60 * (1000 * 1000 * 1000 / pcc_ss_data->pcc_mpar);
+
+	latency_ns = max(latency_ns, pcc_ss_data->pcc_nominal * 1000);
+	latency_ns = max(latency_ns, pcc_ss_data->pcc_mrtt * 1000);
+
+	return latency_ns;
+}
+EXPORT_SYMBOL_GPL(cppc_get_transition_latency);