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cpufreq: powernv: Handle throttling due to Pmax capping at chip level 

The On-Chip-Controller(OCC) can throttle cpu frequency by reducing the
max allowed frequency for that chip if the chip exceeds its power or
temperature limits. As Pmax capping is a chip level condition report
this throttling behavior at chip level and also do not set the global
'throttled' on Pmax capping instead set the per-chip throttled
variable. Report unthrottling if Pmax is restored after throttling.

This patch adds a structure to store chip id and throttled state of
the chip.

Signed-off-by: Shilpasri G Bhat <shilpa.bhat@linux.vnet.ibm.com>
Reviewed-by: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Shilpasri G Bhat 2015-07-16 13:34:18 +05:30 committed by Rafael J. Wysocki
parent a34e63b144
commit 053819e0bf
1 changed files with 55 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

59
drivers/cpufreq/powernv-cpufreq.c
View File

@ -27,6 +27,7 @@
#include <linux/smp.h>
#include <linux/of.h>
#include <linux/reboot.h>
#include <linux/slab.h>
#include <asm/cputhreads.h>
#include <asm/firmware.h>
@ -42,6 +43,13 @@
static struct cpufreq_frequency_table powernv_freqs[POWERNV_MAX_PSTATES+1];
static bool rebooting, throttled;
static struct chip {
unsigned int id;
bool throttled;
} *chips;
static int nr_chips;
/*
* Note: The set of pstates consists of contiguous integers, the
* smallest of which is indicated by powernv_pstate_info.min, the
@ -301,22 +309,33 @@ static inline unsigned int get_nominal_index(void)
static void powernv_cpufreq_throttle_check(unsigned int cpu)
{
unsigned long pmsr;
int pmsr_pmax, pmsr_lp;
int pmsr_pmax, pmsr_lp, i;
pmsr = get_pmspr(SPRN_PMSR);
for (i = 0; i < nr_chips; i++)
if (chips[i].id == cpu_to_chip_id(cpu))
break;
/* Check for Pmax Capping */
pmsr_pmax = (s8)PMSR_MAX(pmsr);
if (pmsr_pmax != powernv_pstate_info.max) {
throttled = true;
pr_info("CPU %d Pmax is reduced to %d\n", cpu, pmsr_pmax);
pr_info("Max allowed Pstate is capped\n");
if (chips[i].throttled)
goto next;
chips[i].throttled = true;
pr_info("CPU %d on Chip %u has Pmax reduced to %d\n", cpu,
chips[i].id, pmsr_pmax);
} else if (chips[i].throttled) {
chips[i].throttled = false;
pr_info("CPU %d on Chip %u has Pmax restored to %d\n", cpu,
chips[i].id, pmsr_pmax);
}
/*
* Check for Psafe by reading LocalPstate
* or check if Psafe_mode_active is set in PMSR.
*/
next:
pmsr_lp = (s8)PMSR_LP(pmsr);
if ((pmsr_lp < powernv_pstate_info.min) ||
(pmsr & PMSR_PSAFE_ENABLE)) {
@ -414,6 +433,33 @@ static struct cpufreq_driver powernv_cpufreq_driver = {
.attr = powernv_cpu_freq_attr,
};
static int init_chip_info(void)
{
unsigned int chip[256];
unsigned int cpu, i;
unsigned int prev_chip_id = UINT_MAX;
for_each_possible_cpu(cpu) {
unsigned int id = cpu_to_chip_id(cpu);
if (prev_chip_id != id) {
prev_chip_id = id;
chip[nr_chips++] = id;
}
}
chips = kmalloc_array(nr_chips, sizeof(struct chip), GFP_KERNEL);
if (!chips)
return -ENOMEM;
for (i = 0; i < nr_chips; i++) {
chips[i].id = chip[i];
chips[i].throttled = false;
}
return 0;
}
static int __init powernv_cpufreq_init(void)
{
int rc = 0;
@ -429,6 +475,11 @@ static int __init powernv_cpufreq_init(void)
return rc;
}
/* Populate chip info */
rc = init_chip_info();
if (rc)
return rc;
register_reboot_notifier(&powernv_cpufreq_reboot_nb);
return cpufreq_register_driver(&powernv_cpufreq_driver);
}