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* pcc-cpufreq.c - Processor Clocking Control firmware cpufreq interface
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* Copyright (C) 2009 Red Hat, Matthew Garrett <mjg@redhat.com>
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* Copyright (C) 2009 Hewlett-Packard Development Company, L.P.
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* Nagananda Chumbalkar <nagananda.chumbalkar@hp.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; version 2 of the License.
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or NON
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* INFRINGEMENT. See the GNU General Public License for more details.
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 675 Mass Ave, Cambridge, MA 02139, USA.
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* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/smp.h>
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#include <linux/sched.h>
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#include <linux/cpufreq.h>
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#include <linux/compiler.h>
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#include <linux/slab.h>
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#include <linux/acpi.h>
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#include <linux/spinlock.h>
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#include <linux/uaccess.h>
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#include <acpi/processor.h>
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#define PCC_VERSION "1.10.00"
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#define POLL_LOOPS 300
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#define CMD_COMPLETE 0x1
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#define CMD_GET_FREQ 0x0
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#define CMD_SET_FREQ 0x1
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struct pcc_register_resource {
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} __attribute__ ((packed));
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struct pcc_memory_resource {
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u64 translation_offset;
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} __attribute__ ((packed));
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static struct cpufreq_driver pcc_cpufreq_driver;
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u32 throttled_frequency;
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u32 minimum_frequency;
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static void __iomem *pcch_virt_addr;
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static struct pcc_header __iomem *pcch_hdr;
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static DEFINE_SPINLOCK(pcc_lock);
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static struct acpi_generic_address doorbell;
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static u64 doorbell_preserve;
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static u64 doorbell_write;
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static u8 OSC_UUID[16] = {0x9F, 0x2C, 0x9B, 0x63, 0x91, 0x70, 0x1f, 0x49,
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0xBB, 0x4F, 0xA5, 0x98, 0x2F, 0xA1, 0xB5, 0x46};
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static struct pcc_cpu __percpu *pcc_cpu_info;
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static int pcc_cpufreq_verify(struct cpufreq_policy *policy)
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cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq,
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policy->cpuinfo.max_freq);
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static inline void pcc_cmd(void)
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acpi_read(&doorbell_value, &doorbell);
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acpi_write((doorbell_value & doorbell_preserve) | doorbell_write,
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for (i = 0; i < POLL_LOOPS; i++) {
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if (ioread16(&pcch_hdr->status) & CMD_COMPLETE)
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static inline void pcc_clear_mapping(void)
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iounmap(pcch_virt_addr);
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pcch_virt_addr = NULL;
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static unsigned int pcc_get_freq(unsigned int cpu)
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struct pcc_cpu *pcc_cpu_data;
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unsigned int curr_freq;
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unsigned int freq_limit;
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spin_lock(&pcc_lock);
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pr_debug("get: get_freq for CPU %d\n", cpu);
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pcc_cpu_data = per_cpu_ptr(pcc_cpu_info, cpu);
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iowrite32(input_buffer,
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(pcch_virt_addr + pcc_cpu_data->input_offset));
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iowrite16(CMD_GET_FREQ, &pcch_hdr->command);
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ioread32(pcch_virt_addr + pcc_cpu_data->output_offset);
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/* Clear the input buffer - we are done with the current command */
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memset_io((pcch_virt_addr + pcc_cpu_data->input_offset), 0, BUF_SZ);
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status = ioread16(&pcch_hdr->status);
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if (status != CMD_COMPLETE) {
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pr_debug("get: FAILED: for CPU %d, status is %d\n",
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iowrite16(0, &pcch_hdr->status);
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curr_freq = (((ioread32(&pcch_hdr->nominal) * (output_buffer & 0xff))
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pr_debug("get: SUCCESS: (virtual) output_offset for cpu %d is "
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"0x%p, contains a value of: 0x%x. Speed is: %d MHz\n",
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cpu, (pcch_virt_addr + pcc_cpu_data->output_offset),
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output_buffer, curr_freq);
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freq_limit = (output_buffer >> 8) & 0xff;
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if (freq_limit != 0xff) {
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pr_debug("get: frequency for cpu %d is being temporarily"
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" capped at %d\n", cpu, curr_freq);
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spin_unlock(&pcc_lock);
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iowrite16(0, &pcch_hdr->status);
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spin_unlock(&pcc_lock);
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static int pcc_cpufreq_target(struct cpufreq_policy *policy,
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unsigned int target_freq,
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unsigned int relation)
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struct pcc_cpu *pcc_cpu_data;
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struct cpufreq_freqs freqs;
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spin_lock(&pcc_lock);
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pcc_cpu_data = per_cpu_ptr(pcc_cpu_info, cpu);
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pr_debug("target: CPU %d should go to target freq: %d "
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"(virtual) input_offset is 0x%p\n",
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(pcch_virt_addr + pcc_cpu_data->input_offset));
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freqs.new = target_freq;
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cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
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input_buffer = 0x1 | (((target_freq * 100)
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/ (ioread32(&pcch_hdr->nominal) * 1000)) << 8);
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iowrite32(input_buffer,
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(pcch_virt_addr + pcc_cpu_data->input_offset));
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iowrite16(CMD_SET_FREQ, &pcch_hdr->command);
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/* Clear the input buffer - we are done with the current command */
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memset_io((pcch_virt_addr + pcc_cpu_data->input_offset), 0, BUF_SZ);
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status = ioread16(&pcch_hdr->status);
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if (status != CMD_COMPLETE) {
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pr_debug("target: FAILED for cpu %d, with status: 0x%x\n",
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iowrite16(0, &pcch_hdr->status);
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cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
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pr_debug("target: was SUCCESSFUL for cpu %d\n", cpu);
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spin_unlock(&pcc_lock);
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iowrite16(0, &pcch_hdr->status);
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spin_unlock(&pcc_lock);
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static int pcc_get_offset(int cpu)
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struct acpi_buffer buffer = {ACPI_ALLOCATE_BUFFER, NULL};
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union acpi_object *pccp, *offset;
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struct pcc_cpu *pcc_cpu_data;
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struct acpi_processor *pr;
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pr = per_cpu(processors, cpu);
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pcc_cpu_data = per_cpu_ptr(pcc_cpu_info, cpu);
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status = acpi_evaluate_object(pr->handle, "PCCP", NULL, &buffer);
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if (ACPI_FAILURE(status))
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pccp = buffer.pointer;
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if (!pccp || pccp->type != ACPI_TYPE_PACKAGE) {
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offset = &(pccp->package.elements[0]);
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if (!offset || offset->type != ACPI_TYPE_INTEGER) {
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pcc_cpu_data->input_offset = offset->integer.value;
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offset = &(pccp->package.elements[1]);
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if (!offset || offset->type != ACPI_TYPE_INTEGER) {
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pcc_cpu_data->output_offset = offset->integer.value;
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memset_io((pcch_virt_addr + pcc_cpu_data->input_offset), 0, BUF_SZ);
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memset_io((pcch_virt_addr + pcc_cpu_data->output_offset), 0, BUF_SZ);
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pr_debug("pcc_get_offset: for CPU %d: pcc_cpu_data "
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"input_offset: 0x%x, pcc_cpu_data output_offset: 0x%x\n",
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cpu, pcc_cpu_data->input_offset, pcc_cpu_data->output_offset);
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kfree(buffer.pointer);
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static int __init pcc_cpufreq_do_osc(acpi_handle *handle)
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struct acpi_object_list input;
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struct acpi_buffer output = {ACPI_ALLOCATE_BUFFER, NULL};
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union acpi_object in_params[4];
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union acpi_object *out_obj;
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input.pointer = in_params;
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in_params[0].type = ACPI_TYPE_BUFFER;
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in_params[0].buffer.length = 16;
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in_params[0].buffer.pointer = OSC_UUID;
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in_params[1].type = ACPI_TYPE_INTEGER;
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in_params[1].integer.value = 1;
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in_params[2].type = ACPI_TYPE_INTEGER;
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in_params[2].integer.value = 2;
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in_params[3].type = ACPI_TYPE_BUFFER;
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in_params[3].buffer.length = 8;
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in_params[3].buffer.pointer = (u8 *)&capabilities;
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capabilities[0] = OSC_QUERY_ENABLE;
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capabilities[1] = 0x1;
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status = acpi_evaluate_object(*handle, "_OSC", &input, &output);
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if (ACPI_FAILURE(status))
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out_obj = output.pointer;
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if (out_obj->type != ACPI_TYPE_BUFFER) {
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errors = *((u32 *)out_obj->buffer.pointer) & ~(1 << 0);
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supported = *((u32 *)(out_obj->buffer.pointer + 4));
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if (!(supported & 0x1)) {
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kfree(output.pointer);
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capabilities[0] = 0x0;
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capabilities[1] = 0x1;
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status = acpi_evaluate_object(*handle, "_OSC", &input, &output);
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if (ACPI_FAILURE(status))
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out_obj = output.pointer;
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if (out_obj->type != ACPI_TYPE_BUFFER) {
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errors = *((u32 *)out_obj->buffer.pointer) & ~(1 << 0);
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supported = *((u32 *)(out_obj->buffer.pointer + 4));
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if (!(supported & 0x1)) {
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kfree(output.pointer);
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static int __init pcc_cpufreq_probe(void)
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struct acpi_buffer output = {ACPI_ALLOCATE_BUFFER, NULL};
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struct pcc_memory_resource *mem_resource;
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struct pcc_register_resource *reg_resource;
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union acpi_object *out_obj, *member;
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acpi_handle handle, osc_handle, pcch_handle;
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status = acpi_get_handle(NULL, "\\_SB", &handle);
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if (ACPI_FAILURE(status))
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status = acpi_get_handle(handle, "PCCH", &pcch_handle);
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if (ACPI_FAILURE(status))
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status = acpi_get_handle(handle, "_OSC", &osc_handle);
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if (ACPI_SUCCESS(status)) {
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ret = pcc_cpufreq_do_osc(&osc_handle);
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pr_debug("probe: _OSC evaluation did not succeed\n");
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/* Firmware's use of _OSC is optional */
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status = acpi_evaluate_object(handle, "PCCH", NULL, &output);
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if (ACPI_FAILURE(status))
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out_obj = output.pointer;
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if (out_obj->type != ACPI_TYPE_PACKAGE) {
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member = &out_obj->package.elements[0];
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if (member->type != ACPI_TYPE_BUFFER) {
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mem_resource = (struct pcc_memory_resource *)member->buffer.pointer;
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pr_debug("probe: mem_resource descriptor: 0x%x,"
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" length: %d, space_id: %d, resource_usage: %d,"
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" type_specific: %d, granularity: 0x%llx,"
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" minimum: 0x%llx, maximum: 0x%llx,"
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" translation_offset: 0x%llx, address_length: 0x%llx\n",
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mem_resource->descriptor, mem_resource->length,
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mem_resource->space_id, mem_resource->resource_usage,
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mem_resource->type_specific, mem_resource->granularity,
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mem_resource->minimum, mem_resource->maximum,
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mem_resource->translation_offset,
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mem_resource->address_length);
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if (mem_resource->space_id != ACPI_ADR_SPACE_SYSTEM_MEMORY) {
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pcch_virt_addr = ioremap_nocache(mem_resource->minimum,
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mem_resource->address_length);
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if (pcch_virt_addr == NULL) {
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pr_debug("probe: could not map shared mem region\n");
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pcch_hdr = pcch_virt_addr;
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pr_debug("probe: PCCH header (virtual) addr: 0x%p\n", pcch_hdr);
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pr_debug("probe: PCCH header is at physical address: 0x%llx,"
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" signature: 0x%x, length: %d bytes, major: %d, minor: %d,"
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" supported features: 0x%x, command field: 0x%x,"
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" status field: 0x%x, nominal latency: %d us\n",
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mem_resource->minimum, ioread32(&pcch_hdr->signature),
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ioread16(&pcch_hdr->length), ioread8(&pcch_hdr->major),
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ioread8(&pcch_hdr->minor), ioread32(&pcch_hdr->features),
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ioread16(&pcch_hdr->command), ioread16(&pcch_hdr->status),
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ioread32(&pcch_hdr->latency));
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pr_debug("probe: min time between commands: %d us,"
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" max time between commands: %d us,"
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" nominal CPU frequency: %d MHz,"
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" minimum CPU frequency: %d MHz,"
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" minimum CPU frequency without throttling: %d MHz\n",
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ioread32(&pcch_hdr->minimum_time),
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ioread32(&pcch_hdr->maximum_time),
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ioread32(&pcch_hdr->nominal),
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ioread32(&pcch_hdr->throttled_frequency),
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ioread32(&pcch_hdr->minimum_frequency));
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member = &out_obj->package.elements[1];
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if (member->type != ACPI_TYPE_BUFFER) {
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reg_resource = (struct pcc_register_resource *)member->buffer.pointer;
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doorbell.space_id = reg_resource->space_id;
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doorbell.bit_width = reg_resource->bit_width;
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doorbell.bit_offset = reg_resource->bit_offset;
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doorbell.access_width = 64;
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doorbell.address = reg_resource->address;
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pr_debug("probe: doorbell: space_id is %d, bit_width is %d, "
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"bit_offset is %d, access_width is %d, address is 0x%llx\n",
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doorbell.space_id, doorbell.bit_width, doorbell.bit_offset,
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doorbell.access_width, reg_resource->address);
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member = &out_obj->package.elements[2];
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if (member->type != ACPI_TYPE_INTEGER) {
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doorbell_preserve = member->integer.value;
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member = &out_obj->package.elements[3];
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if (member->type != ACPI_TYPE_INTEGER) {
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doorbell_write = member->integer.value;
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pr_debug("probe: doorbell_preserve: 0x%llx,"
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" doorbell_write: 0x%llx\n",
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doorbell_preserve, doorbell_write);
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pcc_cpu_info = alloc_percpu(struct pcc_cpu);
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printk(KERN_DEBUG "pcc-cpufreq: (v%s) driver loaded with frequency"
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" limits: %d MHz, %d MHz\n", PCC_VERSION,
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ioread32(&pcch_hdr->minimum_frequency),
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ioread32(&pcch_hdr->nominal));
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kfree(output.pointer);
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kfree(output.pointer);
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static int pcc_cpufreq_cpu_init(struct cpufreq_policy *policy)
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unsigned int cpu = policy->cpu;
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unsigned int result = 0;
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if (!pcch_virt_addr) {
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result = pcc_get_offset(cpu);
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pr_debug("init: PCCP evaluation failed\n");
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policy->max = policy->cpuinfo.max_freq =
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ioread32(&pcch_hdr->nominal) * 1000;
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policy->min = policy->cpuinfo.min_freq =
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ioread32(&pcch_hdr->minimum_frequency) * 1000;
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policy->cur = pcc_get_freq(cpu);
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pr_debug("init: Unable to get current CPU frequency\n");
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pr_debug("init: policy->max is %d, policy->min is %d\n",
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policy->max, policy->min);
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static int pcc_cpufreq_cpu_exit(struct cpufreq_policy *policy)
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static struct cpufreq_driver pcc_cpufreq_driver = {
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.flags = CPUFREQ_CONST_LOOPS,
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.verify = pcc_cpufreq_verify,
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.target = pcc_cpufreq_target,
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.init = pcc_cpufreq_cpu_init,
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.exit = pcc_cpufreq_cpu_exit,
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.name = "pcc-cpufreq",
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.owner = THIS_MODULE,
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static int __init pcc_cpufreq_init(void)
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ret = pcc_cpufreq_probe();
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pr_debug("pcc_cpufreq_init: PCCH evaluation failed\n");
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ret = cpufreq_register_driver(&pcc_cpufreq_driver);
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static void __exit pcc_cpufreq_exit(void)
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cpufreq_unregister_driver(&pcc_cpufreq_driver);
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free_percpu(pcc_cpu_info);
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MODULE_AUTHOR("Matthew Garrett, Naga Chumbalkar");
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MODULE_VERSION(PCC_VERSION);
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MODULE_DESCRIPTION("Processor Clocking Control interface driver");
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MODULE_LICENSE("GPL");
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late_initcall(pcc_cpufreq_init);
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module_exit(pcc_cpufreq_exit);