vga_switcheroo.c

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/*
 * Copyright (c) 2010 Red Hat Inc.
 * Author : Dave Airlie <[email protected]>
 *
 *
 * Licensed under GPLv2
 *
 * vga_switcheroo.c - Support for laptop with dual GPU using one set of outputs

 Switcher interface - methods require for ATPX and DCM
 - switchto - this throws the output MUX switch
 - discrete_set_power - sets the power state for the discrete card

 GPU driver interface
 - set_gpu_state - this should do the equiv of s/r for the card
          - this should *not* set the discrete power state
 - switch_check  - check if the device is in a position to switch now
 */

#include <linux/module.h>
#include <linux/dmi.h>
#include <linux/seq_file.h>
#include <linux/uaccess.h>
#include <linux/fs.h>
#include <linux/debugfs.h>
#include <linux/fb.h>

#include <linux/pci.h>
#include <linux/vga_switcheroo.h>

#include <linux/vgaarb.h>

struct vga_switcheroo_client {
    struct pci_dev *pdev;
    struct fb_info *fb_info;
    int pwr_state;
    const struct vga_switcheroo_client_ops *ops;
    int id;
    bool active;
    struct list_head list;
};

static DEFINE_MUTEX(vgasr_mutex);

struct vgasr_priv {

    bool active;
    bool delayed_switch_active;
    enum vga_switcheroo_client_id delayed_client_id;

    struct dentry *debugfs_root;
    struct dentry *switch_file;

    int registered_clients;
    struct list_head clients;

    struct vga_switcheroo_handler *handler;
};

#define ID_BIT_AUDIO        0x100
#define client_is_audio(c)  ((c)->id & ID_BIT_AUDIO)
#define client_is_vga(c)    ((c)->id == -1 || !client_is_audio(c))
#define client_id(c)        ((c)->id & ~ID_BIT_AUDIO)

static int vga_switcheroo_debugfs_init(struct vgasr_priv *priv);
static void vga_switcheroo_debugfs_fini(struct vgasr_priv *priv);

/* only one switcheroo per system */
static struct vgasr_priv vgasr_priv = {
    .clients = LIST_HEAD_INIT(vgasr_priv.clients),
};

static bool vga_switcheroo_ready(void)
{
    /* we're ready if we get two clients + handler */
    return !vgasr_priv.active &&
           vgasr_priv.registered_clients == 2 && vgasr_priv.handler;
}

static void vga_switcheroo_enable(void)
{
    int ret;
    struct vga_switcheroo_client *client;

    /* call the handler to init */
    if (vgasr_priv.handler->init)
        vgasr_priv.handler->init();

    list_for_each_entry(client, &vgasr_priv.clients, list) {
        if (client->id != -1)
            continue;
        ret = vgasr_priv.handler->get_client_id(client->pdev);
        if (ret < 0)
            return;

        client->id = ret;
    }
    vga_switcheroo_debugfs_init(&vgasr_priv);
    vgasr_priv.active = true;
}

int vga_switcheroo_register_handler(struct vga_switcheroo_handler *handler)
{
    mutex_lock(&vgasr_mutex);
    if (vgasr_priv.handler) {
        mutex_unlock(&vgasr_mutex);
        return -EINVAL;
    }

    vgasr_priv.handler = handler;
    if (vga_switcheroo_ready()) {
        printk(KERN_INFO "vga_switcheroo: enabled\n");
        vga_switcheroo_enable();
    }
    mutex_unlock(&vgasr_mutex);
    return 0;
}
EXPORT_SYMBOL(vga_switcheroo_register_handler);

void vga_switcheroo_unregister_handler(void)
{
    mutex_lock(&vgasr_mutex);
    vgasr_priv.handler = NULL;
    if (vgasr_priv.active) {
        pr_info("vga_switcheroo: disabled\n");
        vga_switcheroo_debugfs_fini(&vgasr_priv);
        vgasr_priv.active = false;
    }
    mutex_unlock(&vgasr_mutex);
}
EXPORT_SYMBOL(vga_switcheroo_unregister_handler);

static int register_client(struct pci_dev *pdev,
               const struct vga_switcheroo_client_ops *ops,
               int id, bool active)
{
    struct vga_switcheroo_client *client;

    client = kzalloc(sizeof(*client), GFP_KERNEL);
    if (!client)
        return -ENOMEM;

    client->pwr_state = VGA_SWITCHEROO_ON;
    client->pdev = pdev;
    client->ops = ops;
    client->id = id;
    client->active = active;

    mutex_lock(&vgasr_mutex);
    list_add_tail(&client->list, &vgasr_priv.clients);
    if (client_is_vga(client))
        vgasr_priv.registered_clients++;

    if (vga_switcheroo_ready()) {
        printk(KERN_INFO "vga_switcheroo: enabled\n");
        vga_switcheroo_enable();
    }
    mutex_unlock(&vgasr_mutex);
    return 0;
}

int vga_switcheroo_register_client(struct pci_dev *pdev,
                   const struct vga_switcheroo_client_ops *ops)
{
    return register_client(pdev, ops, -1,
                   pdev == vga_default_device());
}
EXPORT_SYMBOL(vga_switcheroo_register_client);

int vga_switcheroo_register_audio_client(struct pci_dev *pdev,
                     const struct vga_switcheroo_client_ops *ops,
                     int id, bool active)
{
    return register_client(pdev, ops, id | ID_BIT_AUDIO, active);
}
EXPORT_SYMBOL(vga_switcheroo_register_audio_client);

static struct vga_switcheroo_client *
find_client_from_pci(struct list_head *head, struct pci_dev *pdev)
{
    struct vga_switcheroo_client *client;
    list_for_each_entry(client, head, list)
        if (client->pdev == pdev)
            return client;
    return NULL;
}

static struct vga_switcheroo_client *
find_client_from_id(struct list_head *head, int client_id)
{
    struct vga_switcheroo_client *client;
    list_for_each_entry(client, head, list)
        if (client->id == client_id)
            return client;
    return NULL;
}

static struct vga_switcheroo_client *
find_active_client(struct list_head *head)
{
    struct vga_switcheroo_client *client;
    list_for_each_entry(client, head, list)
        if (client->active && client_is_vga(client))
            return client;
    return NULL;
}

int vga_switcheroo_get_client_state(struct pci_dev *pdev)
{
    struct vga_switcheroo_client *client;

    client = find_client_from_pci(&vgasr_priv.clients, pdev);
    if (!client)
        return VGA_SWITCHEROO_NOT_FOUND;
    if (!vgasr_priv.active)
        return VGA_SWITCHEROO_INIT;
    return client->pwr_state;
}
EXPORT_SYMBOL(vga_switcheroo_get_client_state);

void vga_switcheroo_unregister_client(struct pci_dev *pdev)
{
    struct vga_switcheroo_client *client;

    mutex_lock(&vgasr_mutex);
    client = find_client_from_pci(&vgasr_priv.clients, pdev);
    if (client) {
        if (client_is_vga(client))
            vgasr_priv.registered_clients--;
        list_del(&client->list);
        kfree(client);
    }
    if (vgasr_priv.active && vgasr_priv.registered_clients < 2) {
        printk(KERN_INFO "vga_switcheroo: disabled\n");
        vga_switcheroo_debugfs_fini(&vgasr_priv);
        vgasr_priv.active = false;
    }
    mutex_unlock(&vgasr_mutex);
}
EXPORT_SYMBOL(vga_switcheroo_unregister_client);

void vga_switcheroo_client_fb_set(struct pci_dev *pdev,
                 struct fb_info *info)
{
    struct vga_switcheroo_client *client;

    mutex_lock(&vgasr_mutex);
    client = find_client_from_pci(&vgasr_priv.clients, pdev);
    if (client)
        client->fb_info = info;
    mutex_unlock(&vgasr_mutex);
}
EXPORT_SYMBOL(vga_switcheroo_client_fb_set);

static int vga_switcheroo_show(struct seq_file *m, void *v)
{
    struct vga_switcheroo_client *client;
    int i = 0;
    mutex_lock(&vgasr_mutex);
    list_for_each_entry(client, &vgasr_priv.clients, list) {
        seq_printf(m, "%d:%s%s:%c:%s:%s\n", i,
               client_id(client) == VGA_SWITCHEROO_DIS ? "DIS" : "IGD",
               client_is_vga(client) ? "" : "-Audio",
               client->active ? '+' : ' ',
               client->pwr_state ? "Pwr" : "Off",
               pci_name(client->pdev));
        i++;
    }
    mutex_unlock(&vgasr_mutex);
    return 0;
}

static int vga_switcheroo_debugfs_open(struct inode *inode, struct file *file)
{
    return single_open(file, vga_switcheroo_show, NULL);
}

static int vga_switchon(struct vga_switcheroo_client *client)
{
    if (vgasr_priv.handler->power_state)
        vgasr_priv.handler->power_state(client->id, VGA_SWITCHEROO_ON);
    /* call the driver callback to turn on device */
    client->ops->set_gpu_state(client->pdev, VGA_SWITCHEROO_ON);
    client->pwr_state = VGA_SWITCHEROO_ON;
    return 0;
}

static int vga_switchoff(struct vga_switcheroo_client *client)
{
    /* call the driver callback to turn off device */
    client->ops->set_gpu_state(client->pdev, VGA_SWITCHEROO_OFF);
    if (vgasr_priv.handler->power_state)
        vgasr_priv.handler->power_state(client->id, VGA_SWITCHEROO_OFF);
    client->pwr_state = VGA_SWITCHEROO_OFF;
    return 0;
}

static void set_audio_state(int id, int state)
{
    struct vga_switcheroo_client *client;

    client = find_client_from_id(&vgasr_priv.clients, id | ID_BIT_AUDIO);
    if (client && client->pwr_state != state) {
        client->ops->set_gpu_state(client->pdev, state);
        client->pwr_state = state;
    }
}

/* stage one happens before delay */
static int vga_switchto_stage1(struct vga_switcheroo_client *new_client)
{
    struct vga_switcheroo_client *active;

    active = find_active_client(&vgasr_priv.clients);
    if (!active)
        return 0;

    if (new_client->pwr_state == VGA_SWITCHEROO_OFF)
        vga_switchon(new_client);

    vga_set_default_device(new_client->pdev);
    return 0;
}

/* post delay */
static int vga_switchto_stage2(struct vga_switcheroo_client *new_client)
{
    int ret;
    struct vga_switcheroo_client *active;

    active = find_active_client(&vgasr_priv.clients);
    if (!active)
        return 0;

    active->active = false;

    set_audio_state(active->id, VGA_SWITCHEROO_OFF);

    if (new_client->fb_info) {
        struct fb_event event;
        event.info = new_client->fb_info;
        fb_notifier_call_chain(FB_EVENT_REMAP_ALL_CONSOLE, &event);
    }

    ret = vgasr_priv.handler->switchto(new_client->id);
    if (ret)
        return ret;

    if (new_client->ops->reprobe)
        new_client->ops->reprobe(new_client->pdev);

    if (active->pwr_state == VGA_SWITCHEROO_ON)
        vga_switchoff(active);

    set_audio_state(new_client->id, VGA_SWITCHEROO_ON);

    new_client->active = true;
    return 0;
}

static bool check_can_switch(void)
{
    struct vga_switcheroo_client *client;

    list_for_each_entry(client, &vgasr_priv.clients, list) {
        if (!client->ops->can_switch(client->pdev)) {
            printk(KERN_ERR "vga_switcheroo: client %x refused switch\n", client->id);
            return false;
        }
    }
    return true;
}

static ssize_t
vga_switcheroo_debugfs_write(struct file *filp, const char __user *ubuf,
                 size_t cnt, loff_t *ppos)
{
    char usercmd[64];
    const char *pdev_name;
    int ret;
    bool delay = false, can_switch;
    bool just_mux = false;
    int client_id = -1;
    struct vga_switcheroo_client *client = NULL;

    if (cnt > 63)
        cnt = 63;

    if (copy_from_user(usercmd, ubuf, cnt))
        return -EFAULT;

    mutex_lock(&vgasr_mutex);

    if (!vgasr_priv.active) {
        cnt = -EINVAL;
        goto out;
    }

    /* pwr off the device not in use */
    if (strncmp(usercmd, "OFF", 3) == 0) {
        list_for_each_entry(client, &vgasr_priv.clients, list) {
            if (client->active || client_is_audio(client))
                continue;
            set_audio_state(client->id, VGA_SWITCHEROO_OFF);
            if (client->pwr_state == VGA_SWITCHEROO_ON)
                vga_switchoff(client);
        }
        goto out;
    }
    /* pwr on the device not in use */
    if (strncmp(usercmd, "ON", 2) == 0) {
        list_for_each_entry(client, &vgasr_priv.clients, list) {
            if (client->active || client_is_audio(client))
                continue;
            if (client->pwr_state == VGA_SWITCHEROO_OFF)
                vga_switchon(client);
            set_audio_state(client->id, VGA_SWITCHEROO_ON);
        }
        goto out;
    }

    /* request a delayed switch - test can we switch now */
    if (strncmp(usercmd, "DIGD", 4) == 0) {
        client_id = VGA_SWITCHEROO_IGD;
        delay = true;
    }

    if (strncmp(usercmd, "DDIS", 4) == 0) {
        client_id = VGA_SWITCHEROO_DIS;
        delay = true;
    }

    if (strncmp(usercmd, "IGD", 3) == 0)
        client_id = VGA_SWITCHEROO_IGD;

    if (strncmp(usercmd, "DIS", 3) == 0)
        client_id = VGA_SWITCHEROO_DIS;

    if (strncmp(usercmd, "MIGD", 4) == 0) {
        just_mux = true;
        client_id = VGA_SWITCHEROO_IGD;
    }
    if (strncmp(usercmd, "MDIS", 4) == 0) {
        just_mux = true;
        client_id = VGA_SWITCHEROO_DIS;
    }

    if (client_id == -1)
        goto out;
    client = find_client_from_id(&vgasr_priv.clients, client_id);
    if (!client)
        goto out;

    vgasr_priv.delayed_switch_active = false;

    if (just_mux) {
        ret = vgasr_priv.handler->switchto(client_id);
        goto out;
    }

    if (client->active)
        goto out;

    /* okay we want a switch - test if devices are willing to switch */
    can_switch = check_can_switch();

    if (can_switch == false && delay == false)
        goto out;

    if (can_switch) {
        pdev_name = pci_name(client->pdev);
        ret = vga_switchto_stage1(client);
        if (ret)
            printk(KERN_ERR "vga_switcheroo: switching failed stage 1 %d\n", ret);

        ret = vga_switchto_stage2(client);
        if (ret)
            printk(KERN_ERR "vga_switcheroo: switching failed stage 2 %d\n", ret);

    } else {
        printk(KERN_INFO "vga_switcheroo: setting delayed switch to client %d\n", client->id);
        vgasr_priv.delayed_switch_active = true;
        vgasr_priv.delayed_client_id = client_id;

        ret = vga_switchto_stage1(client);
        if (ret)
            printk(KERN_ERR "vga_switcheroo: delayed switching stage 1 failed %d\n", ret);
    }

out:
    mutex_unlock(&vgasr_mutex);
    return cnt;
}

static const struct file_operations vga_switcheroo_debugfs_fops = {
    .owner = THIS_MODULE,
    .open = vga_switcheroo_debugfs_open,
    .write = vga_switcheroo_debugfs_write,
    .read = seq_read,
    .llseek = seq_lseek,
    .release = single_release,
};

static void vga_switcheroo_debugfs_fini(struct vgasr_priv *priv)
{
    if (priv->switch_file) {
        debugfs_remove(priv->switch_file);
        priv->switch_file = NULL;
    }
    if (priv->debugfs_root) {
        debugfs_remove(priv->debugfs_root);
        priv->debugfs_root = NULL;
    }
}

static int vga_switcheroo_debugfs_init(struct vgasr_priv *priv)
{
    /* already initialised */
    if (priv->debugfs_root)
        return 0;
    priv->debugfs_root = debugfs_create_dir("vgaswitcheroo", NULL);

    if (!priv->debugfs_root) {
        printk(KERN_ERR "vga_switcheroo: Cannot create /sys/kernel/debug/vgaswitcheroo\n");
        goto fail;
    }

    priv->switch_file = debugfs_create_file("switch", 0644,
                        priv->debugfs_root, NULL, &vga_switcheroo_debugfs_fops);
    if (!priv->switch_file) {
        printk(KERN_ERR "vga_switcheroo: cannot create /sys/kernel/debug/vgaswitcheroo/switch\n");
        goto fail;
    }
    return 0;
fail:
    vga_switcheroo_debugfs_fini(priv);
    return -1;
}

int vga_switcheroo_process_delayed_switch(void)
{
    struct vga_switcheroo_client *client;
    const char *pdev_name;
    int ret;
    int err = -EINVAL;

    mutex_lock(&vgasr_mutex);
    if (!vgasr_priv.delayed_switch_active)
        goto err;

    printk(KERN_INFO "vga_switcheroo: processing delayed switch to %d\n", vgasr_priv.delayed_client_id);

    client = find_client_from_id(&vgasr_priv.clients,
                     vgasr_priv.delayed_client_id);
    if (!client || !check_can_switch())
        goto err;

    pdev_name = pci_name(client->pdev);
    ret = vga_switchto_stage2(client);
    if (ret)
        printk(KERN_ERR "vga_switcheroo: delayed switching failed stage 2 %d\n", ret);

    vgasr_priv.delayed_switch_active = false;
    err = 0;
err:
    mutex_unlock(&vgasr_mutex);
    return err;
}
EXPORT_SYMBOL(vga_switcheroo_process_delayed_switch);