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/*
* VGA switcheroo driver for ASUS laptops
*
* Based on drivers/gpu/drm/nouveau/nouveau_acpi.c
*
* Copyright 2011 Red Hat, Inc
*
* Author: Alex Williamson <alex.williamson@redhat.com>
*
* This work is licensed under the terms of the GNU GPL, version 2. See
* the COPYING file in the top-level directory.
*/

#include <linux/moduleparam.h>
#include <linux/module.h>
#include <linux/delay.h>
#include <linux/pci.h>
#include <linux/acpi.h>
#include <linux/slab.h>
#include <linux/version.h>
#include <linux/kallsyms.h>
#include <linux/vga_switcheroo.h>
#include <acpi/acpi_bus.h>
#include <acpi/acpi_drivers.h>
#include <acpi/video.h>

#define DSM_SUPPORTED 0x00
#define DSM_SUPPORTED_FUNCTIONS 0x00

#define DSM_LED 0x02
#define DSM_LED_STATE 0x00
#define DSM_LED_OFF 0x10
#define DSM_LED_STAMINA 0x11
#define DSM_LED_SPEED 0x12

#define DSM_POWER 0x03
#define DSM_POWER_STATE 0x00
#define DSM_POWER_SPEED 0x01
#define DSM_POWER_STAMINA 0x02

static acpi_handle dsm_handle;
static acpi_handle discrete_handle;
static acpi_handle igd_handle;

static struct pci_dev *discrete_dev;
static bool dummy_client;
static bool dummy_client_switched;

static const char dsm_uuid[] = {
0xA0, 0xA0, 0x95, 0x9D, 0x60, 0x00, 0x48, 0x4D,
0xB3, 0x4D, 0x7E, 0x5F, 0xEA, 0x12, 0x9F, 0xD4,
};

static int asus_switcheroo_dsm_call(acpi_handle handle, int func, int arg)
{
struct acpi_buffer output = { ACPI_ALLOCATE_BUFFER, NULL };
struct acpi_object_list input;
union acpi_object params[4], elements[4];
union acpi_object *obj;
int i, err;

input.count = 4;
input.pointer = params;
params[0].type = ACPI_TYPE_BUFFER;
params[0].buffer.length = sizeof(dsm_uuid);
params[0].buffer.pointer = (char *)dsm_uuid;
params[1].type = ACPI_TYPE_INTEGER;
params[1].integer.value = 0; /* revision ID - unused */
params[2].type = ACPI_TYPE_INTEGER;
params[2].integer.value = func;
params[3].type = ACPI_TYPE_PACKAGE;
params[3].package.count = 4;
params[3].package.elements = elements;
for (i = 0; i < 4; i++) {
elements[i].type = ACPI_TYPE_INTEGER;
elements[i].integer.value = (arg >> (i * 8)) & 0xff;
}

err = acpi_evaluate_object(handle, "_DSM", &input, &output);
if (err) {
printk(KERN_INFO "failed to evaluate _DSM: %d\n", err);
return err;
}

obj = (union acpi_object *)output.pointer;

if (obj->type == ACPI_TYPE_INTEGER)
if (obj->integer.value == 0x80000002)
return -ENODEV;

kfree(output.pointer);
return 0;
}

static int asus_switcheroo_acpi_mux(acpi_handle handle)
{
struct acpi_object_list input;
union acpi_object param;
int err;

input.count = 1;
input.pointer = &param;
param.type = ACPI_TYPE_INTEGER;
param.integer.value = 1;

/* I don't really know what these do, but it seems to work */
err = acpi_evaluate_object(handle, "MXMX", &input, NULL);
if (err) {
printk(KERN_INFO "failed to evaluate MXMX: %d\n", err);
return err;
}

err = acpi_evaluate_object(handle, "MXDS", &input, NULL);
if (err) {
printk(KERN_INFO "failed to evaluate MXMX: %d\n", err);
return err;
}
return 0;
}

#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,38)
static void asus_switcheroo_force_nouveau_reprobe(void)
{
void *dev = pci_get_drvdata(discrete_dev);
void (*nouveau_fbcon_hook)(void *);

nouveau_fbcon_hook =
(void *)kallsyms_lookup_name("nouveau_fbcon_output_poll_changed");

if (!nouveau_fbcon_hook) {
printk("Can't hook to nouveau_fbcon_output_poll_changed\n");
return;
}
nouveau_fbcon_hook(dev);
}
#endif

static int asus_switcheroo_switchto(enum vga_switcheroo_client_id id)
{
int ret, dsm_arg;

if (id == VGA_SWITCHEROO_IGD) {
asus_switcheroo_acpi_mux(igd_handle);
dsm_arg = DSM_LED_STAMINA;
} else {
asus_switcheroo_acpi_mux(discrete_handle);
dsm_arg = DSM_LED_SPEED;
}

ret = asus_switcheroo_dsm_call(dsm_handle, DSM_LED, dsm_arg);
#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,38)
if (id == VGA_SWITCHEROO_DIS && !dummy_client)
asus_switcheroo_force_nouveau_reprobe();
#endif
return ret;
}

static int asus_switcheroo_power_state(enum vga_switcheroo_client_id id,
enum vga_switcheroo_state state)
{
int ret, dsm_arg;

if (id == VGA_SWITCHEROO_IGD)
return 0;

if (state == VGA_SWITCHEROO_ON)
dsm_arg = DSM_POWER_SPEED;
else
dsm_arg = DSM_POWER_STAMINA;

ret = asus_switcheroo_dsm_call(dsm_handle, DSM_POWER, dsm_arg);

if (state == VGA_SWITCHEROO_ON)
msleep(10);

return ret;
}

static int asus_switcheroo_handler_init(void)
{
return 0;
}

static int asus_switcheroo_get_client_id(struct pci_dev *pdev)
{
if (pdev->vendor == PCI_VENDOR_ID_INTEL)
return VGA_SWITCHEROO_IGD;

return VGA_SWITCHEROO_DIS;
}

static struct vga_switcheroo_handler asus_dsm_handler = {
.switchto = asus_switcheroo_switchto,
.power_state = asus_switcheroo_power_state,
.init = asus_switcheroo_handler_init,
.get_client_id = asus_switcheroo_get_client_id,
};

static void asus_switcheroo_set_state(struct pci_dev *pdev,
enum vga_switcheroo_state state)
{
if (state == VGA_SWITCHEROO_ON) {
printk(KERN_INFO
"Asus switcheroo: turning on discrete graphics\n");
pci_set_power_state(pdev, PCI_D0);
pci_restore_state(pdev);
if (pci_enable_device(pdev))
printk(KERN_WARNING
"Asus switcher: failed to enable %s\n",
dev_name(&pdev->dev));
pci_set_master(pdev);
dummy_client_switched = true;
} else {
printk(KERN_INFO
"Asus switcheroo: turning off discrete graphics\n");
pci_save_state(pdev);
pci_clear_master(pdev);
pci_disable_device(pdev);
pci_set_power_state(pdev, PCI_D3hot);
}
}

static bool asus_switcheroo_can_switch(struct pci_dev *pdev)
{
return !dummy_client_switched;
}

static bool asus_switcheroo_dsm_pci_probe(struct pci_dev *pdev)
{
acpi_handle handle, test_handle;
acpi_status status;
int ret;

handle = DEVICE_ACPI_HANDLE(&pdev->dev);
if (!handle)
return false;

status = acpi_get_handle(handle, "_DSM", &test_handle);
if (ACPI_FAILURE(status)) {
return false;
}

ret = asus_switcheroo_dsm_call(handle, DSM_SUPPORTED,
DSM_SUPPORTED_FUNCTIONS);
if (ret < 0)
return false;

status = acpi_get_handle(handle, "MXMX", &test_handle);
if (ACPI_FAILURE(status)) {
return false;
}

status = acpi_get_handle(handle, "MXDS", &test_handle);
if (ACPI_FAILURE(status)) {
return false;
}

dsm_handle = handle;
return true;
}

static bool asus_switcheroo_dsm_detect(void)
{
struct pci_dev *pdev = NULL;
int class = PCI_CLASS_DISPLAY_VGA << 8;
int vga_count = 0;

while ((pdev = pci_get_class(class, pdev)) != NULL) {
struct acpi_buffer buf = { ACPI_ALLOCATE_BUFFER, NULL };
acpi_handle handle;

vga_count++;

/* The _DSM actually exists on both devices on this system */
if (!asus_switcheroo_dsm_pci_probe(pdev))
return false;

handle = DEVICE_ACPI_HANDLE(&pdev->dev);
if (!handle)
return false;

if (pdev->vendor == PCI_VENDOR_ID_INTEL) {
igd_handle = handle;
} else {
discrete_handle = handle;
discrete_dev = pdev;
}

acpi_get_name(handle, ACPI_FULL_PATHNAME, &buf);
printk(KERN_INFO "Found VGA device %s (%s): %s\n",
dev_name(&pdev->dev), (char *)buf.pointer,
pdev->vendor == PCI_VENDOR_ID_INTEL ? "IGD" : "DIS");
kfree(buf.pointer);
}

if (vga_count == 2 && dsm_handle && igd_handle && discrete_handle) {
struct acpi_buffer buf = { ACPI_ALLOCATE_BUFFER, NULL };

acpi_get_name(dsm_handle, ACPI_FULL_PATHNAME, &buf);
printk(KERN_INFO
"Asus switcheroo: detected DSM switching method "
"%s handle\n", (char *)buf.pointer);
kfree(buf.pointer);
return true;
}
return false;
}

static int __init asus_switcheroo_init(void)
{
if (!asus_switcheroo_dsm_detect())
return 0;

vga_switcheroo_register_handler(&asus_dsm_handler);

if (dummy_client)
#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,38)
vga_switcheroo_register_client(discrete_dev,
asus_switcheroo_set_state, NULL,
asus_switcheroo_can_switch);
#else
vga_switcheroo_register_client(discrete_dev,
asus_switcheroo_set_state,
asus_switcheroo_can_switch);
#endif
return 0;
}

static void __exit asus_switcheroo_exit(void)
{
if (dummy_client)
vga_switcheroo_unregister_client(discrete_dev);
vga_switcheroo_unregister_handler();
}

module_init(asus_switcheroo_init);
module_exit(asus_switcheroo_exit);

module_param(dummy_client, bool, 0444);
MODULE_PARM_DESC(dummy_client, "Enable dummy VGA switcheroo client support");

MODULE_AUTHOR("Alex Williamson <alex.williamson@redhat.com>");
MODULE_DESCRIPTION("Experimental Asus hybrid graphics switcheroo");
MODULE_LICENSE("GPL v2");
MODULE_VERSION("0.2");
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