cpufreq: Add SFI based cpufreq driver support
This adds the SFI based cpu freq driver for some of the Intel's
Silvermont based Atom architectures like Z34xx and Z35xx.
Signed-off-by: Rudramuni, Vishwesh M <vishwesh.m.rudramuni@intel.com>
Signed-off-by: Srinidhi Kasagar <srinidhi.kasagar@intel.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Len Brown <len.brown@intel.com>
diff --git a/arch/x86/include/uapi/asm/msr-index.h b/arch/x86/include/uapi/asm/msr-index.h
index e21331ce..4f6dae6 100644
--- a/arch/x86/include/uapi/asm/msr-index.h
+++ b/arch/x86/include/uapi/asm/msr-index.h
@@ -318,6 +318,7 @@
#define MSR_IA32_PERF_STATUS 0x00000198
#define MSR_IA32_PERF_CTL 0x00000199
+#define INTEL_PERF_CTL_MASK 0xffff
#define MSR_AMD_PSTATE_DEF_BASE 0xc0010064
#define MSR_AMD_PERF_STATUS 0xc0010063
#define MSR_AMD_PERF_CTL 0xc0010062
diff --git a/drivers/cpufreq/Kconfig.x86 b/drivers/cpufreq/Kconfig.x86
index 89ae88f..c59bdcb 100644
--- a/drivers/cpufreq/Kconfig.x86
+++ b/drivers/cpufreq/Kconfig.x86
@@ -57,6 +57,16 @@
By enabling this option the acpi_cpufreq driver provides the old
entry in addition to the new boost ones, for compatibility reasons.
+config X86_SFI_CPUFREQ
+ tristate "SFI Performance-States driver"
+ depends on X86_INTEL_MID && SFI
+ help
+ This adds a CPUFreq driver for some Silvermont based Intel Atom
+ architectures like Z34xx and Z35xx which enumerate processor
+ performance states through SFI.
+
+ If in doubt, say N.
+
config ELAN_CPUFREQ
tristate "AMD Elan SC400 and SC410"
depends on MELAN
diff --git a/drivers/cpufreq/Makefile b/drivers/cpufreq/Makefile
index 40c53dc..2e50f55e 100644
--- a/drivers/cpufreq/Makefile
+++ b/drivers/cpufreq/Makefile
@@ -41,6 +41,7 @@
obj-$(CONFIG_X86_CPUFREQ_NFORCE2) += cpufreq-nforce2.o
obj-$(CONFIG_X86_INTEL_PSTATE) += intel_pstate.o
obj-$(CONFIG_X86_AMD_FREQ_SENSITIVITY) += amd_freq_sensitivity.o
+obj-$(CONFIG_X86_SFI_CPUFREQ) += sfi-cpufreq.o
##################################################################################
# ARM SoC drivers
diff --git a/drivers/cpufreq/sfi-cpufreq.c b/drivers/cpufreq/sfi-cpufreq.c
new file mode 100644
index 0000000..ffa3389
--- /dev/null
+++ b/drivers/cpufreq/sfi-cpufreq.c
@@ -0,0 +1,136 @@
+/*
+ * 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>
+
+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 = kzalloc(totallen, GFP_KERNEL);
+ if (!sfi_cpufreq_array)
+ return -ENOMEM;
+
+ memcpy(sfi_cpufreq_array, pentry, totallen);
+
+ 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 */
+
+ return cpufreq_table_validate_and_show(policy, freq_table);
+}
+
+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 = kzalloc(sizeof(*freq_table) *
+ (num_freq_table_entries + 1), 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");
