Skip to content
Fetching contributors…
Cannot retrieve contributors at this time
430 lines (361 sloc) 13.2 KB
/**
* Disable discrete graphics (currently nvidia only)
*
* Usage:
* Disable discrete card
* # echo OFF > /proc/acpi/bbswitch
* Enable discrete card
* # echo ON > /proc/acpi/bbswitch
* Get status
* # cat /proc/acpi/bbswitch
*/
#include <linux/pci.h>
#include <linux/acpi.h>
#include <linux/module.h>
#include <asm/uaccess.h>
#include <linux/suspend.h>
#include <linux/seq_file.h>
#define BBSWITCH_VERSION "0.4.2"
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Toggle the discrete graphics card");
MODULE_AUTHOR("Peter Lekensteyn <lekensteyn@gmail.com>");
MODULE_VERSION(BBSWITCH_VERSION);
enum {
CARD_UNCHANGED = -1,
CARD_OFF = 0,
CARD_ON = 1,
};
static int load_state = CARD_UNCHANGED;
MODULE_PARM_DESC(load_state, "Initial card state (0 = off, 1 = on, -1 = unchanged)");
module_param(load_state, int, 0400);
static int unload_state = CARD_UNCHANGED;
MODULE_PARM_DESC(unload_state, "Card state on unload (0 = off, 1 = on, -1 = unchanged)");
module_param(unload_state, int, 0600);
extern struct proc_dir_entry *acpi_root_dir;
static const char acpi_optimus_dsm_muid[16] = {
0xF8, 0xD8, 0x86, 0xA4, 0xDA, 0x0B, 0x1B, 0x47,
0xA7, 0x2B, 0x60, 0x42, 0xA6, 0xB5, 0xBE, 0xE0,
};
static const char acpi_nvidia_dsm_muid[16] = {
0xA0, 0xA0, 0x95, 0x9D, 0x60, 0x00, 0x48, 0x4D,
0xB3, 0x4D, 0x7E, 0x5F, 0xEA, 0x12, 0x9F, 0xD4
};
/*
The next UUID has been found as well in
https://bugs.launchpad.net/lpbugreporter/+bug/752542:
0xD3, 0x73, 0xD8, 0x7E, 0xD0, 0xC2, 0x4F, 0x4E,
0xA8, 0x54, 0x0F, 0x13, 0x17, 0xB0, 0x1C, 0x2C
It looks like something for Intel GPU:
http://lxr.linux.no/#linux+v3.1.5/drivers/gpu/drm/i915/intel_acpi.c
*/
#define DSM_TYPE_UNSUPPORTED 0
#define DSM_TYPE_OPTIMUS 1
#define DSM_TYPE_NVIDIA 2
static int dsm_type = DSM_TYPE_UNSUPPORTED;
static struct pci_dev *dis_dev;
static acpi_handle dis_handle;
/* used for keeping the PM event handler */
static struct notifier_block nb;
/* whether the card was off before suspend or not; on: 0, off: 1 */
int dis_before_suspend_disabled;
static char *buffer_to_string(const char *buffer, size_t n, char *target) {
int i;
for (i=0; i<n; i++) {
snprintf(target + i * 5, 5 * (n - i), "0x%02X,", buffer ? buffer[i] & 0xFF : 0);
}
return target;
}
// Returns 0 if the call succeeded and non-zero otherwise. If the call
// succeeded, the result is stored in "result" providing that the result is an
// integer or a buffer containing 4 values
static int acpi_call_dsm(acpi_handle handle, const char muid[16], int revid,
int func, char args[4], uint32_t *result) {
struct acpi_buffer output = { ACPI_ALLOCATE_BUFFER, NULL };
struct acpi_object_list input;
union acpi_object params[4];
union acpi_object *obj;
int err;
input.count = 4;
input.pointer = params;
params[0].type = ACPI_TYPE_BUFFER;
params[0].buffer.length = 16;
params[0].buffer.pointer = (char *)muid;
params[1].type = ACPI_TYPE_INTEGER;
params[1].integer.value = revid;
params[2].type = ACPI_TYPE_INTEGER;
params[2].integer.value = func;
params[3].type = ACPI_TYPE_BUFFER;
params[3].buffer.length = 4;
if (args) {
params[3].buffer.pointer = args;
} else {
// Some implementations (Asus U36SD) seem to check the args before the
// function ID and crash if it is not a buffer.
params[3].buffer.pointer = (char[4]){0, 0, 0, 0};
}
err = acpi_evaluate_object(handle, "_DSM", &input, &output);
if (err) {
char muid_str[5 * 16];
char args_str[5 * 4];
printk(KERN_WARNING "bbswitch: failed to evaluate _DSM {%s} 0x%X 0x%X"
" {%s}: %s\n",
buffer_to_string(muid, 16, muid_str), revid, func,
buffer_to_string(args, 4, args_str), acpi_format_exception(err));
return err;
}
obj = (union acpi_object *)output.pointer;
if (obj->type == ACPI_TYPE_INTEGER && result) {
*result = obj->integer.value;
} else if (obj->type == ACPI_TYPE_BUFFER) {
if (obj->buffer.length == 4 && result) {
*result = 0;
*result |= obj->buffer.pointer[0];
*result |= (obj->buffer.pointer[1] << 8);
*result |= (obj->buffer.pointer[2] << 16);
*result |= (obj->buffer.pointer[3] << 24);
}
} else {
printk(KERN_WARNING "bbswitch: _DSM call yields an unsupported result"
" type: %X\n", obj->type);
}
kfree(output.pointer);
return 0;
}
// Returns 1 if a _DSM function and its function index exists and 0 otherwise
static int has_dsm_func(const char muid[16], int revid, int sfnc) {
u32 result = 0;
// fail if the _DSM call failed
if (acpi_call_dsm(dis_handle, muid, revid, 0, 0, &result))
return 0;
// ACPI Spec v4 9.14.1: if bit 0 is zero, no function is supported. If
// the n-th bit is enabled, function n is supported
return result & 1 && result & (1 << sfnc);
}
static int bbswitch_optimus_dsm(void) {
if (dsm_type == DSM_TYPE_OPTIMUS) {
char args[] = {1, 0, 0, 3};
u32 result = 0;
if (acpi_call_dsm(dis_handle, acpi_optimus_dsm_muid, 0x100, 0x1A, args,
&result)) {
// failure
return 1;
}
printk(KERN_DEBUG "bbswitch: Result of Optimus _DSM call: %08X\n",
result);
}
return 0;
}
static int bbswitch_acpi_off(void) {
if (dsm_type == DSM_TYPE_NVIDIA) {
char args[] = {2, 0, 0, 0};
u32 result = 0;
if (acpi_call_dsm(dis_handle, acpi_nvidia_dsm_muid, 0x102, 0x3, args,
&result)) {
// failure
return 1;
}
printk(KERN_DEBUG "bbswitch: Result of _DSM call for OFF: %08X\n",
result);
}
return 0;
}
static int bbswitch_acpi_on(void) {
if (dsm_type == DSM_TYPE_NVIDIA) {
char args[] = {1, 0, 0, 0};
u32 result = 0;
if (acpi_call_dsm(dis_handle, acpi_nvidia_dsm_muid, 0x102, 0x3, args,
&result)) {
// failure
return 1;
}
printk(KERN_DEBUG "bbswitch: Result of _DSM call for ON: %08X\n",
result);
}
return 0;
}
// Returns 1 if the card is disabled, 0 if enabled
static int is_card_disabled(void) {
u32 cfg_word;
// read first config word which contains Vendor and Device ID. If all bits
// are enabled, the device is assumed to be off
pci_read_config_dword(dis_dev, 0, &cfg_word);
// if one of the bits is not enabled (the card is enabled), the inverted
// result will be non-zero and hence logical not will make it 0 ("false")
return !~cfg_word;
}
static void bbswitch_off(void) {
if (is_card_disabled())
return;
// to prevent the system from possibly locking up, don't disable the device
// if it's still in use by a driver (i.e. nouveau or nvidia)
if (dis_dev->driver) {
printk(KERN_WARNING "bbswitch: device %s is in use by driver '%s', "
"refusing OFF\n", dev_name(&dis_dev->dev), dis_dev->driver->name);
return;
}
printk(KERN_INFO "bbswitch: disabling discrete graphics\n");
if (bbswitch_optimus_dsm()) {
printk(KERN_WARNING "bbswitch: Optimus ACPI call failed, the device is"
" not disabled\n");
return;
}
pci_save_state(dis_dev);
pci_clear_master(dis_dev);
pci_disable_device(dis_dev);
pci_set_power_state(dis_dev, PCI_D3hot);
if (bbswitch_acpi_off())
printk(KERN_WARNING "bbswitch: The discrete card could not be disabled"
" by a _DSM call\n");
}
static void bbswitch_on(void) {
if (!is_card_disabled())
return;
printk(KERN_INFO "bbswitch: enabling discrete graphics\n");
if (bbswitch_acpi_on())
printk(KERN_WARNING "bbswitch: The discrete card could not be enabled"
" by a _DSM call\n");
pci_set_power_state(dis_dev, PCI_D0);
pci_restore_state(dis_dev);
if (pci_enable_device(dis_dev))
printk(KERN_WARNING "bbswitch: failed to enable %s\n",
dev_name(&dis_dev->dev));
pci_set_master(dis_dev);
}
static ssize_t bbswitch_proc_write(struct file *fp, const char __user *buff,
size_t len, loff_t *off) {
char cmd[8];
if (len >= sizeof(cmd))
len = sizeof(cmd) - 1;
if (copy_from_user(cmd, buff, len))
return -EFAULT;
if (strncmp(cmd, "OFF", 3) == 0)
bbswitch_off();
if (strncmp(cmd, "ON", 2) == 0)
bbswitch_on();
return len;
}
static int bbswitch_proc_show(struct seq_file *seqfp, void *p) {
// show the card state. Example output: 0000:01:00:00 ON
seq_printf(seqfp, "%s %s\n", dev_name(&dis_dev->dev),
is_card_disabled() ? "OFF" : "ON");
return 0;
}
static int bbswitch_proc_open(struct inode *inode, struct file *file) {
return single_open(file, bbswitch_proc_show, NULL);
}
static int bbswitch_pm_handler(struct notifier_block *nbp,
unsigned long event_type, void *p) {
switch (event_type) {
case PM_HIBERNATION_PREPARE:
case PM_SUSPEND_PREPARE:
dis_before_suspend_disabled = is_card_disabled();
// enable the device before suspend to avoid the PCI config space from
// being saved incorrectly
if (dis_before_suspend_disabled)
bbswitch_on();
break;
case PM_POST_HIBERNATION:
case PM_POST_SUSPEND:
case PM_POST_RESTORE:
// after suspend, the card is on, but if it was off before suspend,
// disable it again
if (dis_before_suspend_disabled)
bbswitch_off();
break;
case PM_RESTORE_PREPARE:
// deliberately don't do anything as it does not occur before suspend
// nor hibernate, but before restoring a saved image. In that case,
// either PM_POST_HIBERNATION or PM_POST_RESTORE will be called
break;
}
return 0;
}
static struct file_operations bbswitch_fops = {
.open = bbswitch_proc_open,
.read = seq_read,
.write = bbswitch_proc_write,
.llseek = seq_lseek,
.release= single_release
};
static int __init bbswitch_init(void) {
struct proc_dir_entry *acpi_entry;
struct pci_dev *pdev = NULL;
acpi_handle igd_handle = NULL;
printk(KERN_INFO "bbswitch: version %s\n", BBSWITCH_VERSION);
while ((pdev = pci_get_device(PCI_ANY_ID, PCI_ANY_ID, pdev)) != NULL) {
struct acpi_buffer buf = { ACPI_ALLOCATE_BUFFER, NULL };
acpi_handle handle;
int pci_class = pdev->class >> 8;
if (pci_class != PCI_CLASS_DISPLAY_VGA &&
pci_class != PCI_CLASS_DISPLAY_3D)
continue;
handle = DEVICE_ACPI_HANDLE(&pdev->dev);
if (!handle) {
printk(KERN_WARNING "bbswitch: cannot find ACPI handle for VGA"
" device %s\n", dev_name(&pdev->dev));
continue;
}
acpi_get_name(handle, ACPI_FULL_PATHNAME, &buf);
if (pdev->vendor == PCI_VENDOR_ID_INTEL) {
igd_handle = handle;
printk(KERN_INFO "bbswitch: Found integrated VGA device %s: %s\n",
dev_name(&pdev->dev), (char *)buf.pointer);
} else {
dis_dev = pdev;
dis_handle = handle;
printk(KERN_INFO "bbswitch: Found discrete VGA device %s: %s\n",
dev_name(&pdev->dev), (char *)buf.pointer);
}
kfree(buf.pointer);
}
if (dis_dev == NULL) {
printk(KERN_ERR "bbswitch: No discrete VGA device found\n");
return -ENODEV;
}
if (has_dsm_func(acpi_optimus_dsm_muid, 0x100, 0x1A)) {
dsm_type = DSM_TYPE_OPTIMUS;
printk(KERN_INFO "bbswitch: detected an Optimus _DSM function\n");
} else if (has_dsm_func(acpi_nvidia_dsm_muid, 0x102, 0x3)) {
dsm_type = DSM_TYPE_NVIDIA;
printk(KERN_INFO "bbswitch: detected a nVidia _DSM function\n");
} else {
/* At least two Acer machines are known to use the intel ACPI handle
* with the legacy nvidia DSM */
dis_handle = igd_handle;
if (has_dsm_func(acpi_nvidia_dsm_muid, 0x102, 0x3)) {
dsm_type = DSM_TYPE_NVIDIA;
printk(KERN_INFO "bbswitch: detected a nVidia _DSM function on the"
" integrated video card\n");
} else {
printk(KERN_ERR "bbswitch: No suitable _DSM call found.\n");
return -ENODEV;
}
}
acpi_entry = proc_create("bbswitch", 0664, acpi_root_dir, &bbswitch_fops);
if (acpi_entry == NULL) {
printk(KERN_ERR "bbswitch: Couldn't create proc entry\n");
return -ENOMEM;
}
if (load_state == CARD_ON)
bbswitch_on();
else if (load_state == CARD_OFF)
bbswitch_off();
printk(KERN_INFO "bbswitch: Succesfully loaded. Discrete card %s is %s\n",
dev_name(&dis_dev->dev), is_card_disabled() ? "off" : "on");
nb.notifier_call = &bbswitch_pm_handler;
register_pm_notifier(&nb);
return 0;
}
static void __exit bbswitch_exit(void) {
remove_proc_entry("bbswitch", acpi_root_dir);
if (unload_state == CARD_ON)
bbswitch_on();
else if (unload_state == CARD_OFF)
bbswitch_off();
printk(KERN_INFO "bbswitch: Unloaded. Discrete card %s is %s\n",
dev_name(&dis_dev->dev), is_card_disabled() ? "off" : "on");
if (nb.notifier_call)
unregister_pm_notifier(&nb);
}
module_init(bbswitch_init);
module_exit(bbswitch_exit);
Something went wrong with that request. Please try again.