vga_switcheroo: initial implementation (v15)

Many new laptops now come with 2 gpus, one to be used for low power
modes and one for gaming/on-ac applications. These GPUs are typically
wired to the laptop panel and VGA ports via a multiplexer unit which
is controlled via ACPI methods.

4 combinations of systems typically exist - with 2 ACPI methods.
Intel/ATI - Lenovo W500/T500 - use ATPX ACPI method
ATI/ATI - some ASUS - use ATPX ACPI Method
Intel/Nvidia - - use _DSM ACPI method
Nvidia/Nvidia -  - use _DSM ACPI method.

TODO:
This patch adds support for the ATPX method and initial bits
for the _DSM methods that need to written by someone with
access to the hardware.
Add a proper non-debugfs interface - need to get some proper
testing first.

v2: add power up/down support for both devices
on W500 puts i915/radeon into D3 and cuts power to radeon.

v3: redo probing methods, no DMI list, drm devices call to
register with switcheroo, it tries to find an ATPX method on
any device and once there is two devices + ATPX it inits the
switcher.

v4: ATPX msg handling using buffers - should work on more machines

v5: rearchitect after more mjg59 discussion - move ATPX handling to
    radeon driver.

v6: add file headers + initial nouveau bits (to be filled out).

v7: merge delayed switcher code.

v8: avoid suspend/resume of gpu that is off

v9: rearchitect - mjg59 is always right. - move all ATPX code to
radeon, should allow simpler DSM also proper ATRM handling

v10: add ATRM support for radeon BIOS, add mutex to lock vgasr_priv

v11: fix bug in resuming Intel for 2nd time.

v12: start fixing up nvidia code blindly.

v13: blindly guess at finishing nvidia code

v14: remove radeon audio hacks - fix up intel resume more like upstream

v15: clean up printks + remove unnecessary igd/dis pointers

mount debugfs

/sys/kernel/debug/vgaswitcheroo/switch - should exist if ATPX detected
 + 2 cards.

DIS - immediate change to discrete
IGD - immediate change to IGD
DDIS - delayed change to discrete
DIGD - delayed change to IGD
ON - turn on not in use
OFF - turn off not in use

Tested on W500 (Intel/ATI) and T500 (Intel/ATI)

Signed-off-by: Dave Airlie <airlied@redhat.com>

3 files changed, 467 insertions, 0 deletions

diff --git a/drivers/gpu/vga/Kconfig b/drivers/gpu/vga/Kconfig
index 790e675..6116a01 100644
--- a/drivers/gpu/vga/Kconfig
+++ b/drivers/gpu/vga/Kconfig
@@ -8,3 +8,16 @@ config VGA_ARB
 	  are accessed at same time they need some kind of coordination. Please
 	  see Documentation/vgaarbiter.txt for more details. Select this to
 	  enable VGA arbiter.
+
+config VGA_SWITCHEROO
+	bool "Laptop Hybrid Grapics - GPU switching support"
+	default y
+	depends on X86
+	depends on ACPI
+	help
+	  Many laptops released in 2008/9/10 have two gpus with a multiplxer
+	  to switch between them. This adds support for dynamic switching when
+          X isn't running and delayed switching until the next logoff. This
+	  features is called hybrid graphics, ATI PowerXpress, and Nvidia
+	  HybridPower.
+
diff --git a/drivers/gpu/vga/Makefile b/drivers/gpu/vga/Makefile
index 7cc8c1e..14ca30b 100644
--- a/drivers/gpu/vga/Makefile
+++ b/drivers/gpu/vga/Makefile
@@ -1 +1,2 @@
 obj-$(CONFIG_VGA_ARB)  += vgaarb.o
+obj-$(CONFIG_VGA_SWITCHEROO) += vga_switcheroo.o
diff --git a/drivers/gpu/vga/vga_switcheroo.c b/drivers/gpu/vga/vga_switcheroo.c
new file mode 100644
index 0000000..a3f587a
--- /dev/null
+++ b/drivers/gpu/vga/vga_switcheroo.c
@@ -0,0 +1,453 @@
+/*
+ * Copyright (c) 2010 Red Hat Inc.
+ * Author : Dave Airlie <airlied@redhat.com>
+ *
+ *
+ * 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 <acpi/acpi.h>
+#include <acpi/acpi_bus.h>
+
+#include <linux/pci.h>
+#include <linux/vga_switcheroo.h>
+
+struct vga_switcheroo_client {
+	struct pci_dev *pdev;
+	struct fb_info *fb_info;
+	int pwr_state;
+	void (*set_gpu_state)(struct pci_dev *pdev, enum vga_switcheroo_state);
+	bool (*can_switch)(struct pci_dev *pdev);
+	int id;
+	bool active;
+};
+
+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 vga_switcheroo_client clients[VGA_SWITCHEROO_MAX_CLIENTS];
+
+	struct vga_switcheroo_handler *handler;
+};
+
+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;
+
+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;
+	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;
+	mutex_unlock(&vgasr_mutex);
+}
+EXPORT_SYMBOL(vga_switcheroo_unregister_handler);
+
+static void vga_switcheroo_enable(void)
+{
+	int i;
+	int ret;
+	/* call the handler to init */
+	vgasr_priv.handler->init();
+
+	for (i = 0; i < VGA_SWITCHEROO_MAX_CLIENTS; i++) {
+		ret = vgasr_priv.handler->get_client_id(vgasr_priv.clients[i].pdev);
+		if (ret < 0)
+			return;
+
+		vgasr_priv.clients[i].id = ret;
+	}
+	vga_switcheroo_debugfs_init(&vgasr_priv);
+	vgasr_priv.active = true;
+}
+
+int vga_switcheroo_register_client(struct pci_dev *pdev,
+				   void (*set_gpu_state)(struct pci_dev *pdev, enum vga_switcheroo_state),
+				   bool (*can_switch)(struct pci_dev *pdev))
+{
+	int index;
+
+	mutex_lock(&vgasr_mutex);
+	/* don't do IGD vs DIS here */
+	if (vgasr_priv.registered_clients & 1)
+		index = 1;
+	else
+		index = 0;
+
+	vgasr_priv.clients[index].pwr_state = VGA_SWITCHEROO_ON;
+	vgasr_priv.clients[index].pdev = pdev;
+	vgasr_priv.clients[index].set_gpu_state = set_gpu_state;
+	vgasr_priv.clients[index].can_switch = can_switch;
+	vgasr_priv.clients[index].id = -1;
+	if (pdev->resource[PCI_ROM_RESOURCE].flags & IORESOURCE_ROM_SHADOW)
+		vgasr_priv.clients[index].active = true;
+
+	vgasr_priv.registered_clients |= (1 << index);
+
+	/* if we get two clients + handler */
+	if (vgasr_priv.registered_clients == 0x3 && vgasr_priv.handler) {
+		printk(KERN_INFO "vga_switcheroo: enabled\n");
+		vga_switcheroo_enable();
+	}
+	mutex_unlock(&vgasr_mutex);
+	return 0;
+}
+EXPORT_SYMBOL(vga_switcheroo_register_client);
+
+void vga_switcheroo_unregister_client(struct pci_dev *pdev)
+{
+	int i;
+
+	mutex_lock(&vgasr_mutex);
+	for (i = 0; i < VGA_SWITCHEROO_MAX_CLIENTS; i++) {
+		if (vgasr_priv.clients[i].pdev == pdev) {
+			vgasr_priv.registered_clients &= ~(1 << i);
+			break;
+		}
+	}
+
+	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)
+{
+	int i;
+
+	mutex_lock(&vgasr_mutex);
+	for (i = 0; i < VGA_SWITCHEROO_MAX_CLIENTS; i++) {
+		if (vgasr_priv.clients[i].pdev == pdev) {
+			vgasr_priv.clients[i].fb_info = info;
+			break;
+		}
+	}
+	mutex_unlock(&vgasr_mutex);
+}
+EXPORT_SYMBOL(vga_switcheroo_client_fb_set);
+
+static int vga_switcheroo_show(struct seq_file *m, void *v)
+{
+	int i;
+	mutex_lock(&vgasr_mutex);
+	for (i = 0; i < VGA_SWITCHEROO_MAX_CLIENTS; i++) {
+		seq_printf(m, "%d:%c:%s:%s\n", i,
+			   vgasr_priv.clients[i].active ? '+' : ' ',
+			   vgasr_priv.clients[i].pwr_state ? "Pwr" : "Off",
+			   pci_name(vgasr_priv.clients[i].pdev));
+	}
+	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)
+{
+	int ret;
+
+	ret = vgasr_priv.handler->power_state(client->id, VGA_SWITCHEROO_ON);
+	/* call the driver callback to turn on device */
+	client->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->set_gpu_state(client->pdev, VGA_SWITCHEROO_OFF);
+	vgasr_priv.handler->power_state(client->id, VGA_SWITCHEROO_OFF);
+	client->pwr_state = VGA_SWITCHEROO_OFF;
+	return 0;
+}
+
+static int vga_switchto(struct vga_switcheroo_client *new_client)
+{
+	int ret;
+	int i;
+	struct vga_switcheroo_client *active = NULL;
+
+	if (new_client->active == true)
+		return 0;
+
+	for (i = 0; i < VGA_SWITCHEROO_MAX_CLIENTS; i++) {
+		if (vgasr_priv.clients[i].active == true) {
+			active = &vgasr_priv.clients[i];
+			break;
+		}
+	}
+	if (!active)
+		return 0;
+
+	/* power up the first device */
+	ret = pci_enable_device(new_client->pdev);
+	if (ret)
+		return ret;
+
+	if (new_client->pwr_state == VGA_SWITCHEROO_OFF)
+		vga_switchon(new_client);
+
+	/* swap shadow resource to denote boot VGA device has changed so X starts on new device */
+	active->active = false;
+
+	active->pdev->resource[PCI_ROM_RESOURCE].flags &= ~IORESOURCE_ROM_SHADOW;
+	new_client->pdev->resource[PCI_ROM_RESOURCE].flags |= IORESOURCE_ROM_SHADOW;
+
+	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 (active->pwr_state == VGA_SWITCHEROO_ON)
+		vga_switchoff(active);
+
+	new_client->active = true;
+	return 0;
+}
+
+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 i, ret;
+	bool delay = false, can_switch;
+	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)
+		return -EINVAL;
+
+	/* pwr off the device not in use */
+	if (strncmp(usercmd, "OFF", 3) == 0) {
+		for (i = 0; i < VGA_SWITCHEROO_MAX_CLIENTS; i++) {
+			if (vgasr_priv.clients[i].active)
+				continue;
+			if (vgasr_priv.clients[i].pwr_state == VGA_SWITCHEROO_ON)
+				vga_switchoff(&vgasr_priv.clients[i]);
+		}
+		goto out;
+	}
+	/* pwr on the device not in use */
+	if (strncmp(usercmd, "ON", 2) == 0) {
+		for (i = 0; i < VGA_SWITCHEROO_MAX_CLIENTS; i++) {
+			if (vgasr_priv.clients[i].active)
+				continue;
+			if (vgasr_priv.clients[i].pwr_state == VGA_SWITCHEROO_OFF)
+				vga_switchon(&vgasr_priv.clients[i]);
+		}
+		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 (client_id == -1)
+		goto out;
+
+	for (i = 0; i < VGA_SWITCHEROO_MAX_CLIENTS; i++) {
+		if (vgasr_priv.clients[i].id == client_id) {
+			client = &vgasr_priv.clients[i];
+			break;
+		}
+	}
+
+	vgasr_priv.delayed_switch_active = false;
+	/* okay we want a switch - test if devices are willing to switch */
+	can_switch = true;
+	for (i = 0; i < VGA_SWITCHEROO_MAX_CLIENTS; i++) {
+		can_switch = vgasr_priv.clients[i].can_switch(vgasr_priv.clients[i].pdev);
+		if (can_switch == false) {
+			printk(KERN_ERR "vga_switcheroo: client %d refused switch\n", i);
+			break;
+		}
+	}
+
+	if (can_switch == false && delay == false)
+		goto out;
+
+	if (can_switch == true) {
+		pdev_name = pci_name(client->pdev);
+		ret = vga_switchto(client);
+		if (ret)
+			printk(KERN_ERR "vga_switcheroo: switching failed %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;
+
+		/* we should at least power up the card to
+		   make the switch faster */
+		if (client->pwr_state == VGA_SWITCHEROO_OFF)
+			vga_switchon(client);
+	}
+
+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 = NULL;
+	const char *pdev_name;
+	bool can_switch = true;
+	int i;
+	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);
+
+	for (i = 0; i < VGA_SWITCHEROO_MAX_CLIENTS; i++) {
+		if (vgasr_priv.clients[i].id == vgasr_priv.delayed_client_id)
+			client = &vgasr_priv.clients[i];
+		can_switch = vgasr_priv.clients[i].can_switch(vgasr_priv.clients[i].pdev);
+		if (can_switch == false) {
+			printk(KERN_ERR "vga_switcheroo: client %d refused switch\n", i);
+			break;
+		}
+	}
+
+	if (can_switch == false || client == NULL)
+		goto err;
+
+	pdev_name = pci_name(client->pdev);
+	ret = vga_switchto(client);
+	if (ret)
+		printk(KERN_ERR "vga_switcheroo: delayed switching failed %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);
+