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![Shilpasri G Bhat](/assets/img/avatar_default.png)
This patch ensures the cpus to kexec/reboot at nominal frequency. Nominal frequency is the highest cpu frequency on PowerPC at which the cores can run without getting throttled. If the host kernel had set the cpus to a low pstate and then it kexecs/reboots to a cpufreq disabled kernel it would cause the target kernel to perform poorly. It will also increase the boot up time of the target kernel. So set the cpus to high pstate, in this case to nominal frequency before rebooting to avoid such scenarios. The reboot notifier will set the cpus to nominal frequncy. 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>
400 lines
10 KiB
C
400 lines
10 KiB
C
/*
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* POWERNV cpufreq driver for the IBM POWER processors
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*
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* (C) Copyright IBM 2014
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*
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* Author: Vaidyanathan Srinivasan <svaidy at linux.vnet.ibm.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2, or (at your option)
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* any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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*/
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#define pr_fmt(fmt) "powernv-cpufreq: " fmt
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#include <linux/kernel.h>
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#include <linux/sysfs.h>
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#include <linux/cpumask.h>
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#include <linux/module.h>
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#include <linux/cpufreq.h>
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#include <linux/smp.h>
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#include <linux/of.h>
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#include <linux/reboot.h>
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#include <asm/cputhreads.h>
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#include <asm/firmware.h>
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#include <asm/reg.h>
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#include <asm/smp.h> /* Required for cpu_sibling_mask() in UP configs */
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#define POWERNV_MAX_PSTATES 256
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static struct cpufreq_frequency_table powernv_freqs[POWERNV_MAX_PSTATES+1];
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static bool rebooting;
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/*
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* Note: The set of pstates consists of contiguous integers, the
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* smallest of which is indicated by powernv_pstate_info.min, the
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* largest of which is indicated by powernv_pstate_info.max.
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*
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* The nominal pstate is the highest non-turbo pstate in this
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* platform. This is indicated by powernv_pstate_info.nominal.
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*/
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static struct powernv_pstate_info {
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int min;
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int max;
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int nominal;
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int nr_pstates;
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} powernv_pstate_info;
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/*
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* Initialize the freq table based on data obtained
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* from the firmware passed via device-tree
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*/
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static int init_powernv_pstates(void)
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{
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struct device_node *power_mgt;
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int i, pstate_min, pstate_max, pstate_nominal, nr_pstates = 0;
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const __be32 *pstate_ids, *pstate_freqs;
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u32 len_ids, len_freqs;
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power_mgt = of_find_node_by_path("/ibm,opal/power-mgt");
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if (!power_mgt) {
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pr_warn("power-mgt node not found\n");
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return -ENODEV;
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}
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if (of_property_read_u32(power_mgt, "ibm,pstate-min", &pstate_min)) {
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pr_warn("ibm,pstate-min node not found\n");
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return -ENODEV;
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}
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if (of_property_read_u32(power_mgt, "ibm,pstate-max", &pstate_max)) {
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pr_warn("ibm,pstate-max node not found\n");
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return -ENODEV;
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}
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if (of_property_read_u32(power_mgt, "ibm,pstate-nominal",
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&pstate_nominal)) {
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pr_warn("ibm,pstate-nominal not found\n");
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return -ENODEV;
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}
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pr_info("cpufreq pstate min %d nominal %d max %d\n", pstate_min,
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pstate_nominal, pstate_max);
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pstate_ids = of_get_property(power_mgt, "ibm,pstate-ids", &len_ids);
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if (!pstate_ids) {
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pr_warn("ibm,pstate-ids not found\n");
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return -ENODEV;
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}
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pstate_freqs = of_get_property(power_mgt, "ibm,pstate-frequencies-mhz",
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&len_freqs);
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if (!pstate_freqs) {
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pr_warn("ibm,pstate-frequencies-mhz not found\n");
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return -ENODEV;
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}
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if (len_ids != len_freqs) {
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pr_warn("Entries in ibm,pstate-ids and "
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"ibm,pstate-frequencies-mhz does not match\n");
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}
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nr_pstates = min(len_ids, len_freqs) / sizeof(u32);
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if (!nr_pstates) {
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pr_warn("No PStates found\n");
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return -ENODEV;
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}
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pr_debug("NR PStates %d\n", nr_pstates);
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for (i = 0; i < nr_pstates; i++) {
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u32 id = be32_to_cpu(pstate_ids[i]);
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u32 freq = be32_to_cpu(pstate_freqs[i]);
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pr_debug("PState id %d freq %d MHz\n", id, freq);
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powernv_freqs[i].frequency = freq * 1000; /* kHz */
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powernv_freqs[i].driver_data = id;
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}
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/* End of list marker entry */
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powernv_freqs[i].frequency = CPUFREQ_TABLE_END;
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powernv_pstate_info.min = pstate_min;
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powernv_pstate_info.max = pstate_max;
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powernv_pstate_info.nominal = pstate_nominal;
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powernv_pstate_info.nr_pstates = nr_pstates;
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return 0;
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}
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/* Returns the CPU frequency corresponding to the pstate_id. */
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static unsigned int pstate_id_to_freq(int pstate_id)
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{
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int i;
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i = powernv_pstate_info.max - pstate_id;
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if (i >= powernv_pstate_info.nr_pstates || i < 0) {
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pr_warn("PState id %d outside of PState table, "
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"reporting nominal id %d instead\n",
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pstate_id, powernv_pstate_info.nominal);
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i = powernv_pstate_info.max - powernv_pstate_info.nominal;
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}
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return powernv_freqs[i].frequency;
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}
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/*
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* cpuinfo_nominal_freq_show - Show the nominal CPU frequency as indicated by
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* the firmware
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*/
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static ssize_t cpuinfo_nominal_freq_show(struct cpufreq_policy *policy,
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char *buf)
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{
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return sprintf(buf, "%u\n",
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pstate_id_to_freq(powernv_pstate_info.nominal));
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}
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struct freq_attr cpufreq_freq_attr_cpuinfo_nominal_freq =
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__ATTR_RO(cpuinfo_nominal_freq);
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static struct freq_attr *powernv_cpu_freq_attr[] = {
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&cpufreq_freq_attr_scaling_available_freqs,
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&cpufreq_freq_attr_cpuinfo_nominal_freq,
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NULL,
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};
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/* Helper routines */
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/* Access helpers to power mgt SPR */
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static inline unsigned long get_pmspr(unsigned long sprn)
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{
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switch (sprn) {
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case SPRN_PMCR:
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return mfspr(SPRN_PMCR);
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case SPRN_PMICR:
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return mfspr(SPRN_PMICR);
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case SPRN_PMSR:
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return mfspr(SPRN_PMSR);
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}
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BUG();
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}
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static inline void set_pmspr(unsigned long sprn, unsigned long val)
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{
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switch (sprn) {
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case SPRN_PMCR:
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mtspr(SPRN_PMCR, val);
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return;
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case SPRN_PMICR:
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mtspr(SPRN_PMICR, val);
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return;
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}
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BUG();
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}
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/*
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* Use objects of this type to query/update
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* pstates on a remote CPU via smp_call_function.
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*/
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struct powernv_smp_call_data {
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unsigned int freq;
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int pstate_id;
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};
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/*
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* powernv_read_cpu_freq: Reads the current frequency on this CPU.
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*
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* Called via smp_call_function.
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*
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* Note: The caller of the smp_call_function should pass an argument of
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* the type 'struct powernv_smp_call_data *' along with this function.
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*
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* The current frequency on this CPU will be returned via
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* ((struct powernv_smp_call_data *)arg)->freq;
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*/
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static void powernv_read_cpu_freq(void *arg)
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{
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unsigned long pmspr_val;
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s8 local_pstate_id;
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struct powernv_smp_call_data *freq_data = arg;
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pmspr_val = get_pmspr(SPRN_PMSR);
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/*
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* The local pstate id corresponds bits 48..55 in the PMSR.
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* Note: Watch out for the sign!
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*/
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local_pstate_id = (pmspr_val >> 48) & 0xFF;
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freq_data->pstate_id = local_pstate_id;
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freq_data->freq = pstate_id_to_freq(freq_data->pstate_id);
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pr_debug("cpu %d pmsr %016lX pstate_id %d frequency %d kHz\n",
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raw_smp_processor_id(), pmspr_val, freq_data->pstate_id,
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freq_data->freq);
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}
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/*
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* powernv_cpufreq_get: Returns the CPU frequency as reported by the
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* firmware for CPU 'cpu'. This value is reported through the sysfs
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* file cpuinfo_cur_freq.
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*/
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static unsigned int powernv_cpufreq_get(unsigned int cpu)
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{
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struct powernv_smp_call_data freq_data;
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smp_call_function_any(cpu_sibling_mask(cpu), powernv_read_cpu_freq,
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&freq_data, 1);
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return freq_data.freq;
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}
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/*
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* set_pstate: Sets the pstate on this CPU.
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*
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* This is called via an smp_call_function.
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*
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* The caller must ensure that freq_data is of the type
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* (struct powernv_smp_call_data *) and the pstate_id which needs to be set
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* on this CPU should be present in freq_data->pstate_id.
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*/
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static void set_pstate(void *freq_data)
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{
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unsigned long val;
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unsigned long pstate_ul =
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((struct powernv_smp_call_data *) freq_data)->pstate_id;
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val = get_pmspr(SPRN_PMCR);
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val = val & 0x0000FFFFFFFFFFFFULL;
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pstate_ul = pstate_ul & 0xFF;
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/* Set both global(bits 56..63) and local(bits 48..55) PStates */
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val = val | (pstate_ul << 56) | (pstate_ul << 48);
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pr_debug("Setting cpu %d pmcr to %016lX\n",
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raw_smp_processor_id(), val);
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set_pmspr(SPRN_PMCR, val);
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}
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/*
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* get_nominal_index: Returns the index corresponding to the nominal
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* pstate in the cpufreq table
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*/
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static inline unsigned int get_nominal_index(void)
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{
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return powernv_pstate_info.max - powernv_pstate_info.nominal;
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}
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/*
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* powernv_cpufreq_target_index: Sets the frequency corresponding to
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* the cpufreq table entry indexed by new_index on the cpus in the
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* mask policy->cpus
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*/
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static int powernv_cpufreq_target_index(struct cpufreq_policy *policy,
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unsigned int new_index)
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{
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struct powernv_smp_call_data freq_data;
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if (unlikely(rebooting) && new_index != get_nominal_index())
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return 0;
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freq_data.pstate_id = powernv_freqs[new_index].driver_data;
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/*
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* Use smp_call_function to send IPI and execute the
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* mtspr on target CPU. We could do that without IPI
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* if current CPU is within policy->cpus (core)
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*/
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smp_call_function_any(policy->cpus, set_pstate, &freq_data, 1);
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return 0;
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}
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static int powernv_cpufreq_cpu_init(struct cpufreq_policy *policy)
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{
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int base, i;
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base = cpu_first_thread_sibling(policy->cpu);
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for (i = 0; i < threads_per_core; i++)
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cpumask_set_cpu(base + i, policy->cpus);
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return cpufreq_table_validate_and_show(policy, powernv_freqs);
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}
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static int powernv_cpufreq_reboot_notifier(struct notifier_block *nb,
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unsigned long action, void *unused)
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{
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int cpu;
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struct cpufreq_policy cpu_policy;
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rebooting = true;
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for_each_online_cpu(cpu) {
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cpufreq_get_policy(&cpu_policy, cpu);
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powernv_cpufreq_target_index(&cpu_policy, get_nominal_index());
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}
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return NOTIFY_DONE;
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}
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static struct notifier_block powernv_cpufreq_reboot_nb = {
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.notifier_call = powernv_cpufreq_reboot_notifier,
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};
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static void powernv_cpufreq_stop_cpu(struct cpufreq_policy *policy)
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{
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struct powernv_smp_call_data freq_data;
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freq_data.pstate_id = powernv_pstate_info.min;
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smp_call_function_single(policy->cpu, set_pstate, &freq_data, 1);
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}
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static struct cpufreq_driver powernv_cpufreq_driver = {
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.name = "powernv-cpufreq",
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.flags = CPUFREQ_CONST_LOOPS,
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.init = powernv_cpufreq_cpu_init,
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.verify = cpufreq_generic_frequency_table_verify,
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.target_index = powernv_cpufreq_target_index,
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.get = powernv_cpufreq_get,
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.stop_cpu = powernv_cpufreq_stop_cpu,
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.attr = powernv_cpu_freq_attr,
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};
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static int __init powernv_cpufreq_init(void)
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{
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int rc = 0;
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/* Don't probe on pseries (guest) platforms */
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if (!firmware_has_feature(FW_FEATURE_OPALv3))
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return -ENODEV;
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/* Discover pstates from device tree and init */
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rc = init_powernv_pstates();
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if (rc) {
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pr_info("powernv-cpufreq disabled. System does not support PState control\n");
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return rc;
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}
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register_reboot_notifier(&powernv_cpufreq_reboot_nb);
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return cpufreq_register_driver(&powernv_cpufreq_driver);
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}
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module_init(powernv_cpufreq_init);
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static void __exit powernv_cpufreq_exit(void)
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{
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unregister_reboot_notifier(&powernv_cpufreq_reboot_nb);
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cpufreq_unregister_driver(&powernv_cpufreq_driver);
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}
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module_exit(powernv_cpufreq_exit);
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Vaidyanathan Srinivasan <svaidy at linux.vnet.ibm.com>");
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