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powercap / RAPL: handle atom and core differences
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RAPL implementation on Atom has made some changes that are not compatible
with Core CPUs. Specifically, it is different in the way units are computed
as well as floor frequency is enforced.

This patch uses the per CPU model functions to handle the differences. Intel
Software Developers' Manual has also been updated to reflect the changes in
Table 35-7 V3C.

Signed-off-by: Ajay Thomas <ajay.thomas.david.rajamanickam@intel.com>
Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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Jacob Pan authored and Rafael J. Wysocki committed Nov 11, 2014
1 parent 087e9cb commit 3c2c084
Showing 1 changed file with 139 additions and 77 deletions.
216 changes: 139 additions & 77 deletions drivers/powercap/intel_rapl.c
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Original file line number Diff line number Diff line change
Expand Up @@ -29,6 +29,7 @@
#include <linux/sysfs.h>
#include <linux/cpu.h>
#include <linux/powercap.h>
#include <asm/iosf_mbi.h>

#include <asm/processor.h>
#include <asm/cpu_device_id.h>
Expand Down Expand Up @@ -70,11 +71,6 @@
#define RAPL_PRIMITIVE_DERIVED BIT(1) /* not from raw data */
#define RAPL_PRIMITIVE_DUMMY BIT(2)

/* scale RAPL units to avoid floating point math inside kernel */
#define POWER_UNIT_SCALE (1000000)
#define ENERGY_UNIT_SCALE (1000000)
#define TIME_UNIT_SCALE (1000000)

#define TIME_WINDOW_MAX_MSEC 40000
#define TIME_WINDOW_MIN_MSEC 250

Expand Down Expand Up @@ -175,9 +171,9 @@ struct rapl_package {
unsigned int id; /* physical package/socket id */
unsigned int nr_domains;
unsigned long domain_map; /* bit map of active domains */
unsigned int power_unit_divisor;
unsigned int energy_unit_divisor;
unsigned int time_unit_divisor;
unsigned int power_unit;
unsigned int energy_unit;
unsigned int time_unit;
struct rapl_domain *domains; /* array of domains, sized at runtime */
struct powercap_zone *power_zone; /* keep track of parent zone */
int nr_cpus; /* active cpus on the package, topology info is lost during
Expand All @@ -197,6 +193,9 @@ struct rapl_defaults {
};
static struct rapl_defaults *rapl_defaults;

/* Sideband MBI registers */
#define IOSF_CPU_POWER_BUDGET_CTL (0x2)

#define PACKAGE_PLN_INT_SAVED BIT(0)
#define MAX_PRIM_NAME (32)

Expand Down Expand Up @@ -348,23 +347,13 @@ static int find_nr_power_limit(struct rapl_domain *rd)
static int set_domain_enable(struct powercap_zone *power_zone, bool mode)
{
struct rapl_domain *rd = power_zone_to_rapl_domain(power_zone);
int nr_powerlimit;

if (rd->state & DOMAIN_STATE_BIOS_LOCKED)
return -EACCES;

get_online_cpus();
nr_powerlimit = find_nr_power_limit(rd);
/* here we activate/deactivate the hardware for power limiting */
rapl_write_data_raw(rd, PL1_ENABLE, mode);
/* always enable clamp such that p-state can go below OS requested
* range. power capping priority over guranteed frequency.
*/
rapl_write_data_raw(rd, PL1_CLAMP, mode);
/* some domains have pl2 */
if (nr_powerlimit > 1) {
rapl_write_data_raw(rd, PL2_ENABLE, mode);
rapl_write_data_raw(rd, PL2_CLAMP, mode);
}
rapl_defaults->set_floor_freq(rd, mode);
put_online_cpus();

return 0;
Expand Down Expand Up @@ -662,9 +651,7 @@ static void rapl_init_domains(struct rapl_package *rp)
static u64 rapl_unit_xlate(int package, enum unit_type type, u64 value,
int to_raw)
{
u64 divisor = 1;
int scale = 1; /* scale to user friendly data without floating point */
u64 f, y; /* fraction and exp. used for time unit */
u64 units = 1;
struct rapl_package *rp;

rp = find_package_by_id(package);
Expand All @@ -673,42 +660,24 @@ static u64 rapl_unit_xlate(int package, enum unit_type type, u64 value,

switch (type) {
case POWER_UNIT:
divisor = rp->power_unit_divisor;
scale = POWER_UNIT_SCALE;
units = rp->power_unit;
break;
case ENERGY_UNIT:
scale = ENERGY_UNIT_SCALE;
divisor = rp->energy_unit_divisor;
units = rp->energy_unit;
break;
case TIME_UNIT:
divisor = rp->time_unit_divisor;
scale = TIME_UNIT_SCALE;
/* special processing based on 2^Y*(1+F)/4 = val/divisor, refer
* to Intel Software Developer's manual Vol. 3a, CH 14.7.4.
*/
if (!to_raw) {
f = (value & 0x60) >> 5;
y = value & 0x1f;
value = (1 << y) * (4 + f) * scale / 4;
return div64_u64(value, divisor);
} else {
do_div(value, scale);
value *= divisor;
y = ilog2(value);
f = div64_u64(4 * (value - (1 << y)), 1 << y);
value = (y & 0x1f) | ((f & 0x3) << 5);
return value;
}
break;
return rapl_defaults->compute_time_window(rp, value, to_raw);
case ARBITRARY_UNIT:
default:
return value;
};

if (to_raw)
return div64_u64(value * divisor, scale);
else
return div64_u64(value * scale, divisor);
return div64_u64(value, units);

value *= units;

return value;
}

/* in the order of enum rapl_primitives */
Expand Down Expand Up @@ -842,12 +811,18 @@ static int rapl_write_data_raw(struct rapl_domain *rd,
return 0;
}

static const struct x86_cpu_id energy_unit_quirk_ids[] = {
{ X86_VENDOR_INTEL, 6, 0x37},/* Valleyview */
{}
};

static int rapl_check_unit(struct rapl_package *rp, int cpu)
/*
* Raw RAPL data stored in MSRs are in certain scales. We need to
* convert them into standard units based on the units reported in
* the RAPL unit MSRs. This is specific to CPUs as the method to
* calculate units differ on different CPUs.
* We convert the units to below format based on CPUs.
* i.e.
* energy unit: microJoules : Represented in microJoules by default
* power unit : microWatts : Represented in milliWatts by default
* time unit : microseconds: Represented in seconds by default
*/
static int rapl_check_unit_core(struct rapl_package *rp, int cpu)
{
u64 msr_val;
u32 value;
Expand All @@ -858,36 +833,47 @@ static int rapl_check_unit(struct rapl_package *rp, int cpu)
return -ENODEV;
}

/* Raw RAPL data stored in MSRs are in certain scales. We need to
* convert them into standard units based on the divisors reported in
* the RAPL unit MSRs.
* i.e.
* energy unit: 1/enery_unit_divisor Joules
* power unit: 1/power_unit_divisor Watts
* time unit: 1/time_unit_divisor Seconds
*/
value = (msr_val & ENERGY_UNIT_MASK) >> ENERGY_UNIT_OFFSET;
/* some CPUs have different way to calculate energy unit */
if (x86_match_cpu(energy_unit_quirk_ids))
rp->energy_unit_divisor = 1000000 / (1 << value);
else
rp->energy_unit_divisor = 1 << value;
rp->energy_unit = 1000000 / (1 << value);

value = (msr_val & POWER_UNIT_MASK) >> POWER_UNIT_OFFSET;
rp->power_unit_divisor = 1 << value;
rp->power_unit = 1000000 / (1 << value);

value = (msr_val & TIME_UNIT_MASK) >> TIME_UNIT_OFFSET;
rp->time_unit_divisor = 1 << value;
rp->time_unit = 1000000 / (1 << value);

pr_debug("Physical package %d units: energy=%d, time=%d, power=%d\n",
rp->id,
rp->energy_unit_divisor,
rp->time_unit_divisor,
rp->power_unit_divisor);
pr_debug("Core CPU package %d energy=%duJ, time=%dus, power=%duW\n",
rp->id, rp->energy_unit, rp->time_unit, rp->power_unit);

return 0;
}

static int rapl_check_unit_atom(struct rapl_package *rp, int cpu)
{
u64 msr_val;
u32 value;

if (rdmsrl_safe_on_cpu(cpu, MSR_RAPL_POWER_UNIT, &msr_val)) {
pr_err("Failed to read power unit MSR 0x%x on CPU %d, exit.\n",
MSR_RAPL_POWER_UNIT, cpu);
return -ENODEV;
}
value = (msr_val & ENERGY_UNIT_MASK) >> ENERGY_UNIT_OFFSET;
rp->energy_unit = 1 << value;

value = (msr_val & POWER_UNIT_MASK) >> POWER_UNIT_OFFSET;
rp->power_unit = (1 << value) * 1000;

value = (msr_val & TIME_UNIT_MASK) >> TIME_UNIT_OFFSET;
rp->time_unit = 1000000 / (1 << value);

pr_debug("Atom package %d energy=%duJ, time=%dus, power=%duW\n",
rp->id, rp->energy_unit, rp->time_unit, rp->power_unit);

return 0;
}


/* REVISIT:
* When package power limit is set artificially low by RAPL, LVT
* thermal interrupt for package power limit should be ignored
Expand Down Expand Up @@ -955,10 +941,86 @@ static void package_power_limit_irq_restore(int package_id)
wrmsr_on_cpu(cpu, MSR_IA32_PACKAGE_THERM_INTERRUPT, l, h);
}

static void set_floor_freq_default(struct rapl_domain *rd, bool mode)
{
int nr_powerlimit = find_nr_power_limit(rd);

/* always enable clamp such that p-state can go below OS requested
* range. power capping priority over guranteed frequency.
*/
rapl_write_data_raw(rd, PL1_CLAMP, mode);

/* some domains have pl2 */
if (nr_powerlimit > 1) {
rapl_write_data_raw(rd, PL2_ENABLE, mode);
rapl_write_data_raw(rd, PL2_CLAMP, mode);
}
}

static void set_floor_freq_atom(struct rapl_domain *rd, bool enable)
{
static u32 power_ctrl_orig_val;
u32 mdata;

if (!power_ctrl_orig_val)
iosf_mbi_read(BT_MBI_UNIT_PMC, BT_MBI_PMC_READ,
IOSF_CPU_POWER_BUDGET_CTL, &power_ctrl_orig_val);
mdata = power_ctrl_orig_val;
if (enable) {
mdata &= ~(0x7f << 8);
mdata |= 1 << 8;
}
iosf_mbi_write(BT_MBI_UNIT_PMC, BT_MBI_PMC_WRITE,
IOSF_CPU_POWER_BUDGET_CTL, mdata);
}

static u64 rapl_compute_time_window_core(struct rapl_package *rp, u64 value,
bool to_raw)
{
u64 f, y; /* fraction and exp. used for time unit */

/*
* Special processing based on 2^Y*(1+F/4), refer
* to Intel Software Developer's manual Vol.3B: CH 14.9.3.
*/
if (!to_raw) {
f = (value & 0x60) >> 5;
y = value & 0x1f;
value = (1 << y) * (4 + f) * rp->time_unit / 4;
} else {
do_div(value, rp->time_unit);
y = ilog2(value);
f = div64_u64(4 * (value - (1 << y)), 1 << y);
value = (y & 0x1f) | ((f & 0x3) << 5);
}
return value;
}

static u64 rapl_compute_time_window_atom(struct rapl_package *rp, u64 value,
bool to_raw)
{
/*
* Atom time unit encoding is straight forward val * time_unit,
* where time_unit is default to 1 sec. Never 0.
*/
if (!to_raw)
return (value) ? value *= rp->time_unit : rp->time_unit;
else
value = div64_u64(value, rp->time_unit);

return value;
}

static const struct rapl_defaults rapl_defaults_core = {
.check_unit = rapl_check_unit_core,
.set_floor_freq = set_floor_freq_default,
.compute_time_window = rapl_compute_time_window_core,
};

static const struct rapl_defaults rapl_defaults_atom = {
.check_unit = rapl_check_unit_atom,
.set_floor_freq = set_floor_freq_atom,
.compute_time_window = rapl_compute_time_window_atom,
};

#define RAPL_CPU(_model, _ops) { \
Expand Down Expand Up @@ -1262,7 +1324,7 @@ static int rapl_detect_topology(void)

/* check if the package contains valid domains */
if (rapl_detect_domains(new_package, i) ||
rapl_check_unit(new_package, i)) {
rapl_defaults->check_unit(new_package, i)) {
kfree(new_package->domains);
kfree(new_package);
/* free up the packages already initialized */
Expand Down Expand Up @@ -1317,7 +1379,7 @@ static int rapl_add_package(int cpu)
rp->nr_cpus = 1;
/* check if the package contains valid domains */
if (rapl_detect_domains(rp, cpu) ||
rapl_check_unit(rp, cpu)) {
rapl_defaults->check_unit(rp, cpu)) {
ret = -ENODEV;
goto err_free_package;
}
Expand Down

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