diff options
Diffstat (limited to 'drivers/cpufreq/sfi-cpufreq.c')
| -rw-r--r-- | drivers/cpufreq/sfi-cpufreq.c | 135 |
1 files changed, 135 insertions, 0 deletions
diff --git a/drivers/cpufreq/sfi-cpufreq.c b/drivers/cpufreq/sfi-cpufreq.c new file mode 100644 index 000000000..978770432 --- /dev/null +++ b/drivers/cpufreq/sfi-cpufreq.c @@ -0,0 +1,135 @@ +/* + * SFI Performance States Driver + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License. + * + * This program is distributed in the hope that it will be useful, but + * WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * General Public License for more details. + * + * Author: Vishwesh M Rudramuni <vishwesh.m.rudramuni@intel.com> + * Author: Srinidhi Kasagar <srinidhi.kasagar@intel.com> + */ + +#include <linux/cpufreq.h> +#include <linux/init.h> +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/sfi.h> +#include <linux/slab.h> +#include <linux/smp.h> + +#include <asm/msr.h> + +static struct cpufreq_frequency_table *freq_table; +static struct sfi_freq_table_entry *sfi_cpufreq_array; +static int num_freq_table_entries; + +static int sfi_parse_freq(struct sfi_table_header *table) +{ + struct sfi_table_simple *sb; + struct sfi_freq_table_entry *pentry; + int totallen; + + sb = (struct sfi_table_simple *)table; + num_freq_table_entries = SFI_GET_NUM_ENTRIES(sb, + struct sfi_freq_table_entry); + if (num_freq_table_entries <= 1) { + pr_err("No p-states discovered\n"); + return -ENODEV; + } + + pentry = (struct sfi_freq_table_entry *)sb->pentry; + totallen = num_freq_table_entries * sizeof(*pentry); + + sfi_cpufreq_array = kmemdup(pentry, totallen, GFP_KERNEL); + if (!sfi_cpufreq_array) + return -ENOMEM; + + return 0; +} + +static int sfi_cpufreq_target(struct cpufreq_policy *policy, unsigned int index) +{ + unsigned int next_perf_state = 0; /* Index into perf table */ + u32 lo, hi; + + next_perf_state = policy->freq_table[index].driver_data; + + rdmsr_on_cpu(policy->cpu, MSR_IA32_PERF_CTL, &lo, &hi); + lo = (lo & ~INTEL_PERF_CTL_MASK) | + ((u32) sfi_cpufreq_array[next_perf_state].ctrl_val & + INTEL_PERF_CTL_MASK); + wrmsr_on_cpu(policy->cpu, MSR_IA32_PERF_CTL, lo, hi); + + return 0; +} + +static int sfi_cpufreq_cpu_init(struct cpufreq_policy *policy) +{ + policy->shared_type = CPUFREQ_SHARED_TYPE_HW; + policy->cpuinfo.transition_latency = 100000; /* 100us */ + policy->freq_table = freq_table; + + return 0; +} + +static struct cpufreq_driver sfi_cpufreq_driver = { + .flags = CPUFREQ_CONST_LOOPS, + .verify = cpufreq_generic_frequency_table_verify, + .target_index = sfi_cpufreq_target, + .init = sfi_cpufreq_cpu_init, + .name = "sfi-cpufreq", + .attr = cpufreq_generic_attr, +}; + +static int __init sfi_cpufreq_init(void) +{ + int ret, i; + + /* parse the freq table from SFI */ + ret = sfi_table_parse(SFI_SIG_FREQ, NULL, NULL, sfi_parse_freq); + if (ret) + return ret; + + freq_table = kcalloc(num_freq_table_entries + 1, sizeof(*freq_table), + GFP_KERNEL); + if (!freq_table) { + ret = -ENOMEM; + goto err_free_array; + } + + for (i = 0; i < num_freq_table_entries; i++) { + freq_table[i].driver_data = i; + freq_table[i].frequency = sfi_cpufreq_array[i].freq_mhz * 1000; + } + freq_table[i].frequency = CPUFREQ_TABLE_END; + + ret = cpufreq_register_driver(&sfi_cpufreq_driver); + if (ret) + goto err_free_tbl; + + return ret; + +err_free_tbl: + kfree(freq_table); +err_free_array: + kfree(sfi_cpufreq_array); + return ret; +} +late_initcall(sfi_cpufreq_init); + +static void __exit sfi_cpufreq_exit(void) +{ + cpufreq_unregister_driver(&sfi_cpufreq_driver); + kfree(freq_table); + kfree(sfi_cpufreq_array); +} +module_exit(sfi_cpufreq_exit); + +MODULE_AUTHOR("Vishwesh M Rudramuni <vishwesh.m.rudramuni@intel.com>"); +MODULE_DESCRIPTION("SFI Performance-States Driver"); +MODULE_LICENSE("GPL"); |