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android-kvm / linux / 1833e327a5ea1d1f356fbf6ded0760c9ff4b0594 / . / drivers / acpi / cppc_acpi.c
blob: a1a858ad4d18d57117eaf3e2a65ca26985754f0a [file] [log] [blame]
// 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
struct cppc_attr {
struct attribute attr;
ssize_t (*show)(struct kobject *kobj,
struct attribute *attr, char *buf);
ssize_t (*store)(struct kobject *kobj,
struct attribute *attr, const char *c, ssize_t count);
};
#define define_one_cppc_ro(_name) \
static struct cppc_attr _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 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 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);
}
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) {
pr = all_cpu_data[i];
if (!pr)
continue;
if (cpumask_test_cpu(i, covered_cpus))
continue;
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_possible_cpu(j) {
if (i == j)
continue;
match_pr = all_cpu_data[j];
if (!match_pr)
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;
match_pr->shared_type = pr->shared_type;
cpumask_copy(match_pr->shared_cpu_map,
pr->shared_cpu_map);
}
}
err_ret:
for_each_possible_cpu(i) {
pr = all_cpu_data[i];
if (!pr)
continue;
/* Assume no coordination on any error parsing domain info */
if (retval) {
cpumask_clear(pr->shared_cpu_map);
cpumask_set_cpu(i, pr->shared_cpu_map);
pr->shared_type = CPUFREQ_SHARED_TYPE_ALL;
}
}
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
*/
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;
}
/* Check if CPPC revision + num_ent combination is supported */
static bool is_cppc_supported(int revision, int num_ent)
{
int expected_num_ent;
switch (revision) {
case CPPC_V2_REV:
expected_num_ent = CPPC_V2_NUM_ENT;
break;
case CPPC_V3_REV:
expected_num_ent = CPPC_V3_NUM_ENT;
break;
default:
pr_debug("Firmware exports unsupported CPPC revision: %d\n",
revision);
return false;
}
if (expected_num_ent != num_ent) {
pr_debug("Firmware exports %d entries. Expected: %d for CPPC rev:%d\n",
num_ent, expected_num_ent, revision);
return false;
}
return true;
}
/*
* 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;
} else {
pr_debug("Unexpected entry type(%d) for NumEntries\n",
cpc_obj->type);
goto out_free;
}
cpc_ptr->num_entries = num_ent;
/* 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;
}
cpc_ptr->version = cpc_rev;
if (!is_cppc_supported(cpc_rev, num_ent))
goto out_free;
/* 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;
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);