343 lines
8.7 KiB
C
343 lines
8.7 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 <asm/cputhreads.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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/*
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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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WARN_ON(len_ids != len_freqs);
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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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BUG_ON(i >= powernv_pstate_info.nr_pstates || i < 0);
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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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* 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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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 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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.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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/* 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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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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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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