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linux-next/include/acpi/cppc_acpi.h
Ionela Voinescu a28b2bfc09 cppc_cpufreq: replace per-cpu data array with a list
The cppc_cpudata per-cpu storage was inefficient (1) additional to causing
functional issues (2) when CPUs are hotplugged out, due to per-cpu data
being improperly initialised.

(1) The amount of information needed for CPPC performance control in its
    cpufreq driver depends on the domain (PSD) coordination type:

    ANY:    One set of CPPC control and capability data (e.g desired
            performance, highest/lowest performance, etc) applies to all
            CPUs in the domain.

    ALL:    Same as ANY. To be noted that this type is not currently
            supported. When supported, information about which CPUs
            belong to a domain is needed in order for frequency change
            requests to be sent to each of them.

    HW:     It's necessary to store CPPC control and capability
            information for all the CPUs. HW will then coordinate the
            performance state based on their limitations and requests.

    NONE:   Same as HW. No HW coordination is expected.

    Despite this, the previous initialisation code would indiscriminately
    allocate memory for all CPUs (all_cpu_data) and unnecessarily
    duplicate performance capabilities and the domain sharing mask and type
    for each possible CPU.

(2) With the current per-cpu structure, when having ANY coordination,
    the cppc_cpudata cpu information is not initialised (will remain 0)
    for all CPUs in a policy, other than policy->cpu. When policy->cpu is
    hotplugged out, the driver will incorrectly use the uninitialised (0)
    value of the other CPUs when making frequency changes. Additionally,
    the previous values stored in the perf_ctrls.desired_perf will be
    lost when policy->cpu changes.

Therefore replace the array of per cpu data with a list. The memory for
each structure is allocated at policy init, where a single structure
can be allocated per policy, not per cpu. In order to accommodate the
struct list_head node in the cppc_cpudata structure, the now unused cpu
and cur_policy variables are removed.

For example, on a arm64 Juno platform with 6 CPUs: (0, 1, 2, 3) in PSD1,
(4, 5) in PSD2 - ANY coordination, the memory allocation comparison shows:

Before patch:

 - ANY coordination:
   total    slack      req alloc/free  caller
       0        0        0     0/1     _kernel_size_le_hi32+0x0xffff800008ff7810
       0        0        0     0/6     _kernel_size_le_hi32+0x0xffff800008ff7808
     128       80       48     1/0     _kernel_size_le_hi32+0x0xffff800008ffc070
     768        0      768     6/0     _kernel_size_le_hi32+0x0xffff800008ffc0e4

After patch:

 - ANY coordination:
    total    slack      req alloc/free  caller
     256        0      256     2/0     _kernel_size_le_hi32+0x0xffff800008fed410
       0        0        0     0/2     _kernel_size_le_hi32+0x0xffff800008fed274

Additional notes:
 - A pointer to the policy's cppc_cpudata is stored in policy->driver_data
 - Driver registration is skipped if _CPC entries are not present.

Signed-off-by: Ionela Voinescu <ionela.voinescu@arm.com>
Tested-by: Mian Yousaf Kaukab <ykaukab@suse.de>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2020-12-15 19:19:32 +01:00

147 lines
3.2 KiB
C

/* 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>
*/
#ifndef _CPPC_ACPI_H
#define _CPPC_ACPI_H
#include <linux/acpi.h>
#include <linux/types.h>
#include <acpi/pcc.h>
#include <acpi/processor.h>
/* Support CPPCv2 and CPPCv3 */
#define CPPC_V2_REV 2
#define CPPC_V3_REV 3
#define CPPC_V2_NUM_ENT 21
#define CPPC_V3_NUM_ENT 23
#define PCC_CMD_COMPLETE_MASK (1 << 0)
#define PCC_ERROR_MASK (1 << 2)
#define MAX_CPC_REG_ENT 21
/* CPPC specific PCC commands. */
#define CMD_READ 0
#define CMD_WRITE 1
/* Each register has the folowing format. */
struct cpc_reg {
u8 descriptor;
u16 length;
u8 space_id;
u8 bit_width;
u8 bit_offset;
u8 access_width;
u64 __iomem address;
} __packed;
/*
* Each entry in the CPC table is either
* of type ACPI_TYPE_BUFFER or
* ACPI_TYPE_INTEGER.
*/
struct cpc_register_resource {
acpi_object_type type;
u64 __iomem *sys_mem_vaddr;
union {
struct cpc_reg reg;
u64 int_value;
} cpc_entry;
};
/* Container to hold the CPC details for each CPU */
struct cpc_desc {
int num_entries;
int version;
int cpu_id;
int write_cmd_status;
int write_cmd_id;
struct cpc_register_resource cpc_regs[MAX_CPC_REG_ENT];
struct acpi_psd_package domain_info;
struct kobject kobj;
};
/* These are indexes into the per-cpu cpc_regs[]. Order is important. */
enum cppc_regs {
HIGHEST_PERF,
NOMINAL_PERF,
LOW_NON_LINEAR_PERF,
LOWEST_PERF,
GUARANTEED_PERF,
DESIRED_PERF,
MIN_PERF,
MAX_PERF,
PERF_REDUC_TOLERANCE,
TIME_WINDOW,
CTR_WRAP_TIME,
REFERENCE_CTR,
DELIVERED_CTR,
PERF_LIMITED,
ENABLE,
AUTO_SEL_ENABLE,
AUTO_ACT_WINDOW,
ENERGY_PERF,
REFERENCE_PERF,
LOWEST_FREQ,
NOMINAL_FREQ,
};
/*
* Categorization of registers as described
* in the ACPI v.5.1 spec.
* XXX: Only filling up ones which are used by governors
* today.
*/
struct cppc_perf_caps {
u32 guaranteed_perf;
u32 highest_perf;
u32 nominal_perf;
u32 lowest_perf;
u32 lowest_nonlinear_perf;
u32 lowest_freq;
u32 nominal_freq;
};
struct cppc_perf_ctrls {
u32 max_perf;
u32 min_perf;
u32 desired_perf;
};
struct cppc_perf_fb_ctrs {
u64 reference;
u64 delivered;
u64 reference_perf;
u64 wraparound_time;
};
/* Per CPU container for runtime CPPC management. */
struct cppc_cpudata {
struct list_head node;
struct cppc_perf_caps perf_caps;
struct cppc_perf_ctrls perf_ctrls;
struct cppc_perf_fb_ctrs perf_fb_ctrs;
unsigned int shared_type;
cpumask_var_t shared_cpu_map;
};
extern int cppc_get_desired_perf(int cpunum, u64 *desired_perf);
extern int cppc_get_perf_ctrs(int cpu, struct cppc_perf_fb_ctrs *perf_fb_ctrs);
extern int cppc_set_perf(int cpu, struct cppc_perf_ctrls *perf_ctrls);
extern int cppc_get_perf_caps(int cpu, struct cppc_perf_caps *caps);
extern bool acpi_cpc_valid(void);
extern int acpi_get_psd_map(unsigned int cpu, struct cppc_cpudata *cpu_data);
extern unsigned int cppc_get_transition_latency(int cpu);
extern bool cpc_ffh_supported(void);
extern int cpc_read_ffh(int cpunum, struct cpc_reg *reg, u64 *val);
extern int cpc_write_ffh(int cpunum, struct cpc_reg *reg, u64 val);
#endif /* _CPPC_ACPI_H*/