/*
   *  pcc-cpufreq.c - Processor Clocking Control firmware cpufreq interface
   *
   *  Copyright (C) 2009 Red Hat, Matthew Garrett <mjg@redhat.com>
   *  Copyright (C) 2009 Hewlett-Packard Development Company, L.P.
   *	Nagananda Chumbalkar <nagananda.chumbalkar@hp.com>
   *
   * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   *
   *  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; 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, GOOD TITLE or NON
   *  INFRINGEMENT. See the GNU General Public License for more details.
   *
   *  You should have received a copy of the GNU General Public License along
   *  with this program; if not, write to the Free Software Foundation, Inc.,
   *  675 Mass Ave, Cambridge, MA 02139, USA.
   *
   * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   */
  
  #include <linux/kernel.h>
  #include <linux/module.h>
  #include <linux/init.h>
  #include <linux/smp.h>
  #include <linux/sched.h>
  #include <linux/cpufreq.h>
  #include <linux/compiler.h>

  #include <linux/slab.h>

  
  #include <linux/acpi.h>
  #include <linux/io.h>
  #include <linux/spinlock.h>
  #include <linux/uaccess.h>
  
  #include <acpi/processor.h>

  #define PCC_VERSION	"1.10.00"

  #define POLL_LOOPS 	300
  
  #define CMD_COMPLETE 	0x1
  #define CMD_GET_FREQ 	0x0
  #define CMD_SET_FREQ 	0x1
  
  #define BUF_SZ		4

  struct pcc_register_resource {
  	u8 descriptor;
  	u16 length;
  	u8 space_id;
  	u8 bit_width;
  	u8 bit_offset;
  	u8 access_size;
  	u64 address;
  } __attribute__ ((packed));
  
  struct pcc_memory_resource {
  	u8 descriptor;
  	u16 length;
  	u8 space_id;
  	u8 resource_usage;
  	u8 type_specific;
  	u64 granularity;
  	u64 minimum;
  	u64 maximum;
  	u64 translation_offset;
  	u64 address_length;
  } __attribute__ ((packed));
  
  static struct cpufreq_driver pcc_cpufreq_driver;
  
  struct pcc_header {
  	u32 signature;
  	u16 length;
  	u8 major;
  	u8 minor;
  	u32 features;
  	u16 command;
  	u16 status;
  	u32 latency;
  	u32 minimum_time;
  	u32 maximum_time;
  	u32 nominal;
  	u32 throttled_frequency;
  	u32 minimum_frequency;
  };
  
  static void __iomem *pcch_virt_addr;
  static struct pcc_header __iomem *pcch_hdr;
  
  static DEFINE_SPINLOCK(pcc_lock);
  
  static struct acpi_generic_address doorbell;
  
  static u64 doorbell_preserve;
  static u64 doorbell_write;

  static u8 OSC_UUID[16] = {0x9F, 0x2C, 0x9B, 0x63, 0x91, 0x70, 0x1f, 0x49,

  			  0xBB, 0x4F, 0xA5, 0x98, 0x2F, 0xA1, 0xB5, 0x46};
  
  struct pcc_cpu {
  	u32 input_offset;
  	u32 output_offset;
  };

  static struct pcc_cpu __percpu *pcc_cpu_info;

  
  static int pcc_cpufreq_verify(struct cpufreq_policy *policy)
  {

  	cpufreq_verify_within_cpu_limits(policy);

  	return 0;
  }
  
  static inline void pcc_cmd(void)
  {
  	u64 doorbell_value;
  	int i;
  
  	acpi_read(&doorbell_value, &doorbell);
  	acpi_write((doorbell_value & doorbell_preserve) | doorbell_write,
  		   &doorbell);
  
  	for (i = 0; i < POLL_LOOPS; i++) {
  		if (ioread16(&pcch_hdr->status) & CMD_COMPLETE)
  			break;
  	}
  }
  
  static inline void pcc_clear_mapping(void)
  {
  	if (pcch_virt_addr)
  		iounmap(pcch_virt_addr);
  	pcch_virt_addr = NULL;
  }
  
  static unsigned int pcc_get_freq(unsigned int cpu)
  {
  	struct pcc_cpu *pcc_cpu_data;
  	unsigned int curr_freq;
  	unsigned int freq_limit;
  	u16 status;
  	u32 input_buffer;
  	u32 output_buffer;
  
  	spin_lock(&pcc_lock);

  	pr_debug("get: get_freq for CPU %d
  ", cpu);

  	pcc_cpu_data = per_cpu_ptr(pcc_cpu_info, cpu);
  
  	input_buffer = 0x1;
  	iowrite32(input_buffer,
  			(pcch_virt_addr + pcc_cpu_data->input_offset));
  	iowrite16(CMD_GET_FREQ, &pcch_hdr->command);
  
  	pcc_cmd();
  
  	output_buffer =
  		ioread32(pcch_virt_addr + pcc_cpu_data->output_offset);
  
  	/* Clear the input buffer - we are done with the current command */
  	memset_io((pcch_virt_addr + pcc_cpu_data->input_offset), 0, BUF_SZ);
  
  	status = ioread16(&pcch_hdr->status);
  	if (status != CMD_COMPLETE) {

  		pr_debug("get: FAILED: for CPU %d, status is %d
  ",

  			cpu, status);
  		goto cmd_incomplete;
  	}
  	iowrite16(0, &pcch_hdr->status);
  	curr_freq = (((ioread32(&pcch_hdr->nominal) * (output_buffer & 0xff))
  			/ 100) * 1000);

  	pr_debug("get: SUCCESS: (virtual) output_offset for cpu %d is "
  		"0x%p, contains a value of: 0x%x. Speed is: %d MHz
  ",

  		cpu, (pcch_virt_addr + pcc_cpu_data->output_offset),
  		output_buffer, curr_freq);
  
  	freq_limit = (output_buffer >> 8) & 0xff;
  	if (freq_limit != 0xff) {

  		pr_debug("get: frequency for cpu %d is being temporarily"

  			" capped at %d
  ", cpu, curr_freq);
  	}
  
  	spin_unlock(&pcc_lock);
  	return curr_freq;
  
  cmd_incomplete:
  	iowrite16(0, &pcch_hdr->status);
  	spin_unlock(&pcc_lock);

  	return 0;

  }
  
  static int pcc_cpufreq_target(struct cpufreq_policy *policy,
  			      unsigned int target_freq,
  			      unsigned int relation)
  {
  	struct pcc_cpu *pcc_cpu_data;
  	struct cpufreq_freqs freqs;
  	u16 status;
  	u32 input_buffer;
  	int cpu;

  	cpu = policy->cpu;
  	pcc_cpu_data = per_cpu_ptr(pcc_cpu_info, cpu);

  	pr_debug("target: CPU %d should go to target freq: %d "
  		"(virtual) input_offset is 0x%p
  ",

  		cpu, target_freq,
  		(pcch_virt_addr + pcc_cpu_data->input_offset));

  	freqs.old = policy->cur;

  	freqs.new = target_freq;

  	cpufreq_freq_transition_begin(policy, &freqs);

  	spin_lock(&pcc_lock);

  
  	input_buffer = 0x1 | (((target_freq * 100)
  			       / (ioread32(&pcch_hdr->nominal) * 1000)) << 8);
  	iowrite32(input_buffer,
  			(pcch_virt_addr + pcc_cpu_data->input_offset));
  	iowrite16(CMD_SET_FREQ, &pcch_hdr->command);
  
  	pcc_cmd();
  
  	/* Clear the input buffer - we are done with the current command */
  	memset_io((pcch_virt_addr + pcc_cpu_data->input_offset), 0, BUF_SZ);
  
  	status = ioread16(&pcch_hdr->status);

  	iowrite16(0, &pcch_hdr->status);

  	cpufreq_freq_transition_end(policy, &freqs, status != CMD_COMPLETE);

  	spin_unlock(&pcc_lock);

  	if (status != CMD_COMPLETE) {

  		pr_debug("target: FAILED for cpu %d, with status: 0x%x
  ",

  			cpu, status);

  		return -EINVAL;

  	}

  	pr_debug("target: was SUCCESSFUL for cpu %d
  ", cpu);

  
  	return 0;

  }
  
  static int pcc_get_offset(int cpu)
  {
  	acpi_status status;
  	struct acpi_buffer buffer = {ACPI_ALLOCATE_BUFFER, NULL};
  	union acpi_object *pccp, *offset;
  	struct pcc_cpu *pcc_cpu_data;
  	struct acpi_processor *pr;
  	int ret = 0;
  
  	pr = per_cpu(processors, cpu);
  	pcc_cpu_data = per_cpu_ptr(pcc_cpu_info, cpu);

  	if (!pr)
  		return -ENODEV;

  	status = acpi_evaluate_object(pr->handle, "PCCP", NULL, &buffer);
  	if (ACPI_FAILURE(status))
  		return -ENODEV;
  
  	pccp = buffer.pointer;
  	if (!pccp || pccp->type != ACPI_TYPE_PACKAGE) {
  		ret = -ENODEV;
  		goto out_free;
  	};
  
  	offset = &(pccp->package.elements[0]);
  	if (!offset || offset->type != ACPI_TYPE_INTEGER) {
  		ret = -ENODEV;
  		goto out_free;
  	}
  
  	pcc_cpu_data->input_offset = offset->integer.value;
  
  	offset = &(pccp->package.elements[1]);
  	if (!offset || offset->type != ACPI_TYPE_INTEGER) {
  		ret = -ENODEV;
  		goto out_free;
  	}
  
  	pcc_cpu_data->output_offset = offset->integer.value;
  
  	memset_io((pcch_virt_addr + pcc_cpu_data->input_offset), 0, BUF_SZ);
  	memset_io((pcch_virt_addr + pcc_cpu_data->output_offset), 0, BUF_SZ);

  	pr_debug("pcc_get_offset: for CPU %d: pcc_cpu_data "

  		"input_offset: 0x%x, pcc_cpu_data output_offset: 0x%x
  ",
  		cpu, pcc_cpu_data->input_offset, pcc_cpu_data->output_offset);
  out_free:
  	kfree(buffer.pointer);
  	return ret;
  }
  
  static int __init pcc_cpufreq_do_osc(acpi_handle *handle)
  {
  	acpi_status status;
  	struct acpi_object_list input;
  	struct acpi_buffer output = {ACPI_ALLOCATE_BUFFER, NULL};
  	union acpi_object in_params[4];
  	union acpi_object *out_obj;
  	u32 capabilities[2];
  	u32 errors;
  	u32 supported;
  	int ret = 0;
  
  	input.count = 4;
  	input.pointer = in_params;

  	in_params[0].type               = ACPI_TYPE_BUFFER;
  	in_params[0].buffer.length      = 16;
  	in_params[0].buffer.pointer     = OSC_UUID;
  	in_params[1].type               = ACPI_TYPE_INTEGER;
  	in_params[1].integer.value      = 1;
  	in_params[2].type               = ACPI_TYPE_INTEGER;
  	in_params[2].integer.value      = 2;
  	in_params[3].type               = ACPI_TYPE_BUFFER;
  	in_params[3].buffer.length      = 8;
  	in_params[3].buffer.pointer     = (u8 *)&capabilities;
  
  	capabilities[0] = OSC_QUERY_ENABLE;
  	capabilities[1] = 0x1;
  
  	status = acpi_evaluate_object(*handle, "_OSC", &input, &output);
  	if (ACPI_FAILURE(status))
  		return -ENODEV;
  
  	if (!output.length)
  		return -ENODEV;
  
  	out_obj = output.pointer;
  	if (out_obj->type != ACPI_TYPE_BUFFER) {
  		ret = -ENODEV;
  		goto out_free;
  	}
  
  	errors = *((u32 *)out_obj->buffer.pointer) & ~(1 << 0);
  	if (errors) {
  		ret = -ENODEV;
  		goto out_free;
  	}
  
  	supported = *((u32 *)(out_obj->buffer.pointer + 4));
  	if (!(supported & 0x1)) {
  		ret = -ENODEV;
  		goto out_free;
  	}
  
  	kfree(output.pointer);
  	capabilities[0] = 0x0;
  	capabilities[1] = 0x1;
  
  	status = acpi_evaluate_object(*handle, "_OSC", &input, &output);
  	if (ACPI_FAILURE(status))
  		return -ENODEV;
  
  	if (!output.length)
  		return -ENODEV;
  
  	out_obj = output.pointer;

  	if (out_obj->type != ACPI_TYPE_BUFFER) {
  		ret = -ENODEV;
  		goto out_free;
  	}

  
  	errors = *((u32 *)out_obj->buffer.pointer) & ~(1 << 0);

  	if (errors) {
  		ret = -ENODEV;
  		goto out_free;
  	}

  
  	supported = *((u32 *)(out_obj->buffer.pointer + 4));

  	if (!(supported & 0x1)) {
  		ret = -ENODEV;
  		goto out_free;
  	}

  
  out_free:
  	kfree(output.pointer);
  	return ret;
  }
  
  static int __init pcc_cpufreq_probe(void)
  {
  	acpi_status status;
  	struct acpi_buffer output = {ACPI_ALLOCATE_BUFFER, NULL};
  	struct pcc_memory_resource *mem_resource;
  	struct pcc_register_resource *reg_resource;
  	union acpi_object *out_obj, *member;

  	acpi_handle handle, osc_handle;

  	int ret = 0;
  
  	status = acpi_get_handle(NULL, "\\_SB", &handle);
  	if (ACPI_FAILURE(status))
  		return -ENODEV;

  	if (!acpi_has_method(handle, "PCCH"))

  		return -ENODEV;

  	status = acpi_get_handle(handle, "_OSC", &osc_handle);
  	if (ACPI_SUCCESS(status)) {
  		ret = pcc_cpufreq_do_osc(&osc_handle);
  		if (ret)

  			pr_debug("probe: _OSC evaluation did not succeed
  ");

  		/* Firmware's use of _OSC is optional */
  		ret = 0;
  	}
  
  	status = acpi_evaluate_object(handle, "PCCH", NULL, &output);
  	if (ACPI_FAILURE(status))
  		return -ENODEV;
  
  	out_obj = output.pointer;
  	if (out_obj->type != ACPI_TYPE_PACKAGE) {
  		ret = -ENODEV;
  		goto out_free;
  	}
  
  	member = &out_obj->package.elements[0];
  	if (member->type != ACPI_TYPE_BUFFER) {
  		ret = -ENODEV;
  		goto out_free;
  	}
  
  	mem_resource = (struct pcc_memory_resource *)member->buffer.pointer;

  	pr_debug("probe: mem_resource descriptor: 0x%x,"

  		" length: %d, space_id: %d, resource_usage: %d,"
  		" type_specific: %d, granularity: 0x%llx,"
  		" minimum: 0x%llx, maximum: 0x%llx,"
  		" translation_offset: 0x%llx, address_length: 0x%llx
  ",
  		mem_resource->descriptor, mem_resource->length,
  		mem_resource->space_id, mem_resource->resource_usage,
  		mem_resource->type_specific, mem_resource->granularity,
  		mem_resource->minimum, mem_resource->maximum,
  		mem_resource->translation_offset,
  		mem_resource->address_length);
  
  	if (mem_resource->space_id != ACPI_ADR_SPACE_SYSTEM_MEMORY) {
  		ret = -ENODEV;
  		goto out_free;
  	}
  
  	pcch_virt_addr = ioremap_nocache(mem_resource->minimum,
  					mem_resource->address_length);
  	if (pcch_virt_addr == NULL) {

  		pr_debug("probe: could not map shared mem region
  ");

  		ret = -ENOMEM;

  		goto out_free;
  	}
  	pcch_hdr = pcch_virt_addr;

  	pr_debug("probe: PCCH header (virtual) addr: 0x%p
  ", pcch_hdr);
  	pr_debug("probe: PCCH header is at physical address: 0x%llx,"

  		" signature: 0x%x, length: %d bytes, major: %d, minor: %d,"
  		" supported features: 0x%x, command field: 0x%x,"
  		" status field: 0x%x, nominal latency: %d us
  ",
  		mem_resource->minimum, ioread32(&pcch_hdr->signature),
  		ioread16(&pcch_hdr->length), ioread8(&pcch_hdr->major),
  		ioread8(&pcch_hdr->minor), ioread32(&pcch_hdr->features),
  		ioread16(&pcch_hdr->command), ioread16(&pcch_hdr->status),
  		ioread32(&pcch_hdr->latency));

  	pr_debug("probe: min time between commands: %d us,"

  		" max time between commands: %d us,"
  		" nominal CPU frequency: %d MHz,"
  		" minimum CPU frequency: %d MHz,"
  		" minimum CPU frequency without throttling: %d MHz
  ",
  		ioread32(&pcch_hdr->minimum_time),
  		ioread32(&pcch_hdr->maximum_time),
  		ioread32(&pcch_hdr->nominal),
  		ioread32(&pcch_hdr->throttled_frequency),
  		ioread32(&pcch_hdr->minimum_frequency));
  
  	member = &out_obj->package.elements[1];
  	if (member->type != ACPI_TYPE_BUFFER) {
  		ret = -ENODEV;
  		goto pcch_free;
  	}
  
  	reg_resource = (struct pcc_register_resource *)member->buffer.pointer;
  
  	doorbell.space_id = reg_resource->space_id;
  	doorbell.bit_width = reg_resource->bit_width;
  	doorbell.bit_offset = reg_resource->bit_offset;

  	doorbell.access_width = 4;

  	doorbell.address = reg_resource->address;

  	pr_debug("probe: doorbell: space_id is %d, bit_width is %d, "

  		"bit_offset is %d, access_width is %d, address is 0x%llx
  ",
  		doorbell.space_id, doorbell.bit_width, doorbell.bit_offset,
  		doorbell.access_width, reg_resource->address);
  
  	member = &out_obj->package.elements[2];
  	if (member->type != ACPI_TYPE_INTEGER) {
  		ret = -ENODEV;
  		goto pcch_free;
  	}
  
  	doorbell_preserve = member->integer.value;
  
  	member = &out_obj->package.elements[3];
  	if (member->type != ACPI_TYPE_INTEGER) {
  		ret = -ENODEV;
  		goto pcch_free;
  	}
  
  	doorbell_write = member->integer.value;

  	pr_debug("probe: doorbell_preserve: 0x%llx,"

  		" doorbell_write: 0x%llx
  ",
  		doorbell_preserve, doorbell_write);
  
  	pcc_cpu_info = alloc_percpu(struct pcc_cpu);
  	if (!pcc_cpu_info) {
  		ret = -ENOMEM;
  		goto pcch_free;
  	}
  
  	printk(KERN_DEBUG "pcc-cpufreq: (v%s) driver loaded with frequency"
  	       " limits: %d MHz, %d MHz
  ", PCC_VERSION,
  	       ioread32(&pcch_hdr->minimum_frequency),
  	       ioread32(&pcch_hdr->nominal));
  	kfree(output.pointer);
  	return ret;
  pcch_free:
  	pcc_clear_mapping();
  out_free:
  	kfree(output.pointer);
  	return ret;
  }
  
  static int pcc_cpufreq_cpu_init(struct cpufreq_policy *policy)
  {
  	unsigned int cpu = policy->cpu;
  	unsigned int result = 0;
  
  	if (!pcch_virt_addr) {
  		result = -1;

  		goto out;

  	}
  
  	result = pcc_get_offset(cpu);
  	if (result) {

  		pr_debug("init: PCCP evaluation failed
  ");

  		goto out;

  	}
  
  	policy->max = policy->cpuinfo.max_freq =
  		ioread32(&pcch_hdr->nominal) * 1000;
  	policy->min = policy->cpuinfo.min_freq =
  		ioread32(&pcch_hdr->minimum_frequency) * 1000;

  	pr_debug("init: policy->max is %d, policy->min is %d
  ",

  		policy->max, policy->min);

  out:

  	return result;
  }
  
  static int pcc_cpufreq_cpu_exit(struct cpufreq_policy *policy)
  {
  	return 0;
  }
  
  static struct cpufreq_driver pcc_cpufreq_driver = {
  	.flags = CPUFREQ_CONST_LOOPS,
  	.get = pcc_get_freq,
  	.verify = pcc_cpufreq_verify,
  	.target = pcc_cpufreq_target,
  	.init = pcc_cpufreq_cpu_init,
  	.exit = pcc_cpufreq_cpu_exit,
  	.name = "pcc-cpufreq",

  };
  
  static int __init pcc_cpufreq_init(void)
  {
  	int ret;
  
  	if (acpi_disabled)
  		return 0;
  
  	ret = pcc_cpufreq_probe();
  	if (ret) {

  		pr_debug("pcc_cpufreq_init: PCCH evaluation failed
  ");

  		return ret;
  	}
  
  	ret = cpufreq_register_driver(&pcc_cpufreq_driver);
  
  	return ret;
  }
  
  static void __exit pcc_cpufreq_exit(void)
  {
  	cpufreq_unregister_driver(&pcc_cpufreq_driver);
  
  	pcc_clear_mapping();
  
  	free_percpu(pcc_cpu_info);
  }

  static const struct acpi_device_id processor_device_ids[] = {
  	{ACPI_PROCESSOR_OBJECT_HID, },
  	{ACPI_PROCESSOR_DEVICE_HID, },
  	{},
  };
  MODULE_DEVICE_TABLE(acpi, processor_device_ids);

  MODULE_AUTHOR("Matthew Garrett, Naga Chumbalkar");
  MODULE_VERSION(PCC_VERSION);
  MODULE_DESCRIPTION("Processor Clocking Control interface driver");
  MODULE_LICENSE("GPL");
  
  late_initcall(pcc_cpufreq_init);
  module_exit(pcc_cpufreq_exit);