linux-surface/patches/5.11/0006-surface-hotplug.patch

From c4a51a33b30769caab6ac407e3c5ce8c7658d42c Mon Sep 17 00:00:00 2001
From: Maximilian Luz <luzmaximilian@gmail.com>
Date: Thu, 4 Feb 2021 23:06:40 +0100
Subject: [PATCH] PCI: Run platform power transition on initial D0 entry

On some devices and platforms, the initial platform power state is not
in sync with the power state of the PCI device.

pci_enable_device_flags() updates the state of a PCI device by reading
from the PCI_PM_CTRL register. This may change the stored power state of
the device without running the appropriate platform power transition.

Due to the stored power-state being changed, the later call to
pci_set_power_state(..., PCI_D0) in do_pci_enable_device() can evaluate
to a no-op if the stored state has been changed to D0 via that. This
will then prevent the appropriate platform power transition to be run,
which can on some devices and platforms lead to platform and PCI power
state being entirely different, i.e. out-of-sync. On ACPI platforms,
this can lead to power resources not being turned on, even though they
are marked as required for D0.

Specifically, on the Microsoft Surface Book 2 and 3, some ACPI power
regions that should be "on" for the D0 state (and others) are
initialized as "off" in ACPI, whereas the PCI device is in D0. As the
state is updated in pci_enable_device_flags() without ensuring that the
platform state is also updated, the power resource will never be
properly turned on. Instead, it lives in a sort of on-but-marked-as-off
zombie-state, which confuses things down the line when attempting to
transition the device into D3cold: As the resource is already marked as
off, it won't be turned off and the device does not fully enter D3cold,
causing increased power consumption during (runtime-)suspend.

By replacing pci_set_power_state() in do_pci_enable_device() with
pci_power_up(), we can force pci_platform_power_transition() to be
called, which will then check if the platform power state needs updating
and appropriate actions need to be taken.

Signed-off-by: Maximilian Luz <luzmaximilian@gmail.com>

Patchset: surface-hotplug
---
 drivers/pci/pci.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index ba791165ed19..0fa8e52208fe 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -1800,7 +1800,7 @@ static int do_pci_enable_device(struct pci_dev *dev, int bars)
 	u16 cmd;
 	u8 pin;
 
-	err = pci_set_power_state(dev, PCI_D0);
+	err = pci_power_up(dev);
 	if (err < 0 && err != -EIO)
 		return err;
 
-- 
2.30.1

From e795af3b2f568aa849a0f3278327fe80bc7b1fb9 Mon Sep 17 00:00:00 2001
From: Maximilian Luz <luzmaximilian@gmail.com>
Date: Fri, 5 Feb 2021 02:26:57 +0100
Subject: [PATCH] platform/surface: Add Surface Hot-Plug driver

Some Surface Book 2 and 3 models have a discrete GPU (dGPU) that is
hot-pluggable. On those devices, the dGPU is contained in the base,
which can be separated from the tablet part (containing CPU and
touchscreen) while the device is running.

It (in general) is presented as/behaves like a standard PCIe hot-plug
capable device, however, this device can also be put into D3cold. In
D3cold, the device itself is turned off and can thus not submit any
standard PCIe hot-plug events. To properly detect hot-(un)plugging while
the dGPU is in D3cold, out-of-band signaling is required. Without this,
the device state will only get updated during the next bus-check, eg.
via a manually issued lspci call.

This commit adds a driver to handle out-of-band PCIe hot-(un)plug events
on Microsoft Surface devices. On those devices, said events can be
detected via GPIO interrupts, which are then forwarded to the
corresponding ACPI DSM calls by this driver. The DSM then takes care of
issuing the appropriate bus-/device-check, causing the PCI core to
properly pick up the device change.

Signed-off-by: Maximilian Luz <luzmaximilian@gmail.com>
Link: https://lore.kernel.org/r/20210205012657.1951753-1-luzmaximilian@gmail.com
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Patchset: surface-hotplug
---
 MAINTAINERS                                |   6 +
 drivers/platform/surface/Kconfig           |  19 ++
 drivers/platform/surface/Makefile          |   1 +
 drivers/platform/surface/surface_hotplug.c | 282 +++++++++++++++++++++
 4 files changed, 308 insertions(+)
 create mode 100644 drivers/platform/surface/surface_hotplug.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 2144ec466377..a4a0519ce88c 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -11824,6 +11824,12 @@ L:	platform-driver-x86@vger.kernel.org
 S:	Maintained
 F:	drivers/hid/surface-hid/
 
+MICROSOFT SURFACE HOT-PLUG DRIVER
+M:	Maximilian Luz <luzmaximilian@gmail.com>
+L:	platform-driver-x86@vger.kernel.org
+S:	Maintained
+F:	drivers/platform/surface/surface_hotplug.c
+
 MICROSOFT SURFACE PRO 3 BUTTON DRIVER
 M:	Chen Yu <yu.c.chen@intel.com>
 L:	platform-driver-x86@vger.kernel.org
diff --git a/drivers/platform/surface/Kconfig b/drivers/platform/surface/Kconfig
index 3ceeb316d56e..2784a480f310 100644
--- a/drivers/platform/surface/Kconfig
+++ b/drivers/platform/surface/Kconfig
@@ -140,6 +140,25 @@ config SURFACE_GPE
 	  accordingly. It is required on those devices to allow wake-ups from
 	  suspend by opening the lid.
 
+config SURFACE_HOTPLUG
+	tristate "Surface Hot-Plug Driver"
+	depends on GPIOLIB
+	help
+	  Driver for out-of-band hot-plug event signaling on Microsoft Surface
+	  devices with hot-pluggable PCIe cards.
+
+	  This driver is used on Surface Book (2 and 3) devices with a
+	  hot-pluggable discrete GPU (dGPU). When not in use, the dGPU on those
+	  devices can enter D3cold, which prevents in-band (standard) PCIe
+	  hot-plug signaling. Thus, without this driver, detaching the base
+	  containing the dGPU will not correctly update the state of the
+	  corresponding PCIe device if it is in D3cold. This driver adds support
+	  for out-of-band hot-plug notifications, ensuring that the device state
+	  is properly updated even when the device in question is in D3cold.
+
+	  Select M or Y here, if you want to (fully) support hot-plugging of
+	  dGPU devices on the Surface Book 2 and/or 3 during D3cold.
+
 config SURFACE_PERFMODE
 	tristate "Surface Performance-Mode Driver"
 	depends on SURFACE_AGGREGATOR_BUS
diff --git a/drivers/platform/surface/Makefile b/drivers/platform/surface/Makefile
index 31098983decc..a103fdb3ef1a 100644
--- a/drivers/platform/surface/Makefile
+++ b/drivers/platform/surface/Makefile
@@ -14,5 +14,6 @@ obj-$(CONFIG_SURFACE_AGGREGATOR_REGISTRY) += surface_aggregator_registry.o
 obj-$(CONFIG_SURFACE_BOOK1_DGPU_SWITCH) += surfacebook1_dgpu_switch.o
 obj-$(CONFIG_SURFACE_DTX)		+= surface_dtx.o
 obj-$(CONFIG_SURFACE_GPE)		+= surface_gpe.o
+obj-$(CONFIG_SURFACE_HOTPLUG)		+= surface_hotplug.o
 obj-$(CONFIG_SURFACE_PERFMODE)		+= surface_perfmode.o
 obj-$(CONFIG_SURFACE_PRO3_BUTTON)	+= surfacepro3_button.o
diff --git a/drivers/platform/surface/surface_hotplug.c b/drivers/platform/surface/surface_hotplug.c
new file mode 100644
index 000000000000..cfcc15cfbacb
--- /dev/null
+++ b/drivers/platform/surface/surface_hotplug.c
@@ -0,0 +1,282 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Surface Book (2 and later) hot-plug driver.
+ *
+ * Surface Book devices (can) have a hot-pluggable discrete GPU (dGPU). This
+ * driver is responsible for out-of-band hot-plug event signaling on these
+ * devices. It is specifically required when the hot-plug device is in D3cold
+ * and can thus not generate PCIe hot-plug events itself.
+ *
+ * Event signaling is handled via ACPI, which will generate the appropriate
+ * device-check notifications to be picked up by the PCIe hot-plug driver.
+ *
+ * Copyright (C) 2019-2021 Maximilian Luz <luzmaximilian@gmail.com>
+ */
+
+#include <linux/acpi.h>
+#include <linux/gpio.h>
+#include <linux/interrupt.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/platform_device.h>
+
+static const struct acpi_gpio_params shps_base_presence_int   = { 0, 0, false };
+static const struct acpi_gpio_params shps_base_presence       = { 1, 0, false };
+static const struct acpi_gpio_params shps_device_power_int    = { 2, 0, false };
+static const struct acpi_gpio_params shps_device_power        = { 3, 0, false };
+static const struct acpi_gpio_params shps_device_presence_int = { 4, 0, false };
+static const struct acpi_gpio_params shps_device_presence     = { 5, 0, false };
+
+static const struct acpi_gpio_mapping shps_acpi_gpios[] = {
+	{ "base_presence-int-gpio",   &shps_base_presence_int,   1 },
+	{ "base_presence-gpio",       &shps_base_presence,       1 },
+	{ "device_power-int-gpio",    &shps_device_power_int,    1 },
+	{ "device_power-gpio",        &shps_device_power,        1 },
+	{ "device_presence-int-gpio", &shps_device_presence_int, 1 },
+	{ "device_presence-gpio",     &shps_device_presence,     1 },
+	{ },
+};
+
+/* 5515a847-ed55-4b27-8352-cd320e10360a */
+static const guid_t shps_dsm_guid =
+	GUID_INIT(0x5515a847, 0xed55, 0x4b27, 0x83, 0x52, 0xcd, 0x32, 0x0e, 0x10, 0x36, 0x0a);
+
+#define SHPS_DSM_REVISION		1
+
+enum shps_dsm_fn {
+	SHPS_DSM_FN_PCI_NUM_ENTRIES	= 0x01,
+	SHPS_DSM_FN_PCI_GET_ENTRIES	= 0x02,
+	SHPS_DSM_FN_IRQ_BASE_PRESENCE	= 0x03,
+	SHPS_DSM_FN_IRQ_DEVICE_POWER	= 0x04,
+	SHPS_DSM_FN_IRQ_DEVICE_PRESENCE	= 0x05,
+};
+
+enum shps_irq_type {
+	/* NOTE: Must be in order of enum shps_dsm_fn above. */
+	SHPS_IRQ_TYPE_BASE_PRESENCE	= 0,
+	SHPS_IRQ_TYPE_DEVICE_POWER	= 1,
+	SHPS_IRQ_TYPE_DEVICE_PRESENCE	= 2,
+	SHPS_NUM_IRQS,
+};
+
+static const char *const shps_gpio_names[] = {
+	[SHPS_IRQ_TYPE_BASE_PRESENCE]	= "base_presence",
+	[SHPS_IRQ_TYPE_DEVICE_POWER]	= "device_power",
+	[SHPS_IRQ_TYPE_DEVICE_PRESENCE]	= "device_presence",
+};
+
+struct shps_device {
+	struct mutex lock[SHPS_NUM_IRQS];  /* Protects update in shps_dsm_notify_irq() */
+	struct gpio_desc *gpio[SHPS_NUM_IRQS];
+	unsigned int irq[SHPS_NUM_IRQS];
+};
+
+#define SHPS_IRQ_NOT_PRESENT		((unsigned int)-1)
+
+static enum shps_dsm_fn shps_dsm_fn_for_irq(enum shps_irq_type type)
+{
+	return SHPS_DSM_FN_IRQ_BASE_PRESENCE + type;
+}
+
+static void shps_dsm_notify_irq(struct platform_device *pdev, enum shps_irq_type type)
+{
+	struct shps_device *sdev = platform_get_drvdata(pdev);
+	acpi_handle handle = ACPI_HANDLE(&pdev->dev);
+	union acpi_object *result;
+	union acpi_object param;
+	int value;
+
+	mutex_lock(&sdev->lock[type]);
+
+	value = gpiod_get_value_cansleep(sdev->gpio[type]);
+	if (value < 0) {
+		mutex_unlock(&sdev->lock[type]);
+		dev_err(&pdev->dev, "failed to get gpio: %d (irq=%d)\n", type, value);
+		return;
+	}
+
+	dev_dbg(&pdev->dev, "IRQ notification via DSM (irq=%d, value=%d)\n", type, value);
+
+	param.type = ACPI_TYPE_INTEGER;
+	param.integer.value = value;
+
+	result = acpi_evaluate_dsm(handle, &shps_dsm_guid, SHPS_DSM_REVISION,
+				   shps_dsm_fn_for_irq(type), &param);
+
+	if (!result) {
+		dev_err(&pdev->dev, "IRQ notification via DSM failed (irq=%d, gpio=%d)\n",
+			type, value);
+
+	} else if (result->type != ACPI_TYPE_BUFFER) {
+		dev_err(&pdev->dev,
+			"IRQ notification via DSM failed: unexpected result type (irq=%d, gpio=%d)\n",
+			type, value);
+
+	} else if (result->buffer.length != 1 || result->buffer.pointer[0] != 0) {
+		dev_err(&pdev->dev,
+			"IRQ notification via DSM failed: unexpected result value (irq=%d, gpio=%d)\n",
+			type, value);
+	}
+
+	mutex_unlock(&sdev->lock[type]);
+
+	if (result)
+		ACPI_FREE(result);
+}
+
+static irqreturn_t shps_handle_irq(int irq, void *data)
+{
+	struct platform_device *pdev = data;
+	struct shps_device *sdev = platform_get_drvdata(pdev);
+	int type;
+
+	/* Figure out which IRQ we're handling. */
+	for (type = 0; type < SHPS_NUM_IRQS; type++)
+		if (irq == sdev->irq[type])
+			break;
+
+	/* We should have found our interrupt, if not: this is a bug. */
+	if (WARN(type >= SHPS_NUM_IRQS, "invalid IRQ number: %d\n", irq))
+		return IRQ_HANDLED;
+
+	/* Forward interrupt to ACPI via DSM. */
+	shps_dsm_notify_irq(pdev, type);
+	return IRQ_HANDLED;
+}
+
+static int shps_setup_irq(struct platform_device *pdev, enum shps_irq_type type)
+{
+	unsigned long flags = IRQF_ONESHOT | IRQF_TRIGGER_FALLING | IRQF_TRIGGER_RISING;
+	struct shps_device *sdev = platform_get_drvdata(pdev);
+	struct gpio_desc *gpiod;
+	acpi_handle handle = ACPI_HANDLE(&pdev->dev);
+	const char *irq_name;
+	const int dsm = shps_dsm_fn_for_irq(type);
+	int status, irq;
+
+	/*
+	 * Only set up interrupts that we actually need: The Surface Book 3
+	 * does not have a DSM for base presence, so don't set up an interrupt
+	 * for that.
+	 */
+	if (!acpi_check_dsm(handle, &shps_dsm_guid, SHPS_DSM_REVISION, BIT(dsm))) {
+		dev_dbg(&pdev->dev, "IRQ notification via DSM not present (irq=%d)\n", type);
+		return 0;
+	}
+
+	gpiod = devm_gpiod_get(&pdev->dev, shps_gpio_names[type], GPIOD_ASIS);
+	if (IS_ERR(gpiod))
+		return PTR_ERR(gpiod);
+
+	irq = gpiod_to_irq(gpiod);
+	if (irq < 0)
+		return irq;
+
+	irq_name = devm_kasprintf(&pdev->dev, GFP_KERNEL, "shps-irq-%d", type);
+	if (!irq_name)
+		return -ENOMEM;
+
+	status = devm_request_threaded_irq(&pdev->dev, irq, NULL, shps_handle_irq,
+					   flags, irq_name, pdev);
+	if (status)
+		return status;
+
+	dev_dbg(&pdev->dev, "set up irq %d as type %d\n", irq, type);
+
+	sdev->gpio[type] = gpiod;
+	sdev->irq[type] = irq;
+
+	return 0;
+}
+
+static int surface_hotplug_remove(struct platform_device *pdev)
+{
+	struct shps_device *sdev = platform_get_drvdata(pdev);
+	int i;
+
+	/* Ensure that IRQs have been fully handled and won't trigger any more. */
+	for (i = 0; i < SHPS_NUM_IRQS; i++) {
+		if (sdev->irq[i] != SHPS_IRQ_NOT_PRESENT)
+			disable_irq(sdev->irq[i]);
+
+		mutex_destroy(&sdev->lock[i]);
+	}
+
+	return 0;
+}
+
+static int surface_hotplug_probe(struct platform_device *pdev)
+{
+	struct shps_device *sdev;
+	int status, i;
+
+	/*
+	 * The MSHW0153 device is also present on the Surface Laptop 3,
+	 * however that doesn't have a hot-pluggable PCIe device. It also
+	 * doesn't have any GPIO interrupts/pins under the MSHW0153, so filter
+	 * it out here.
+	 */
+	if (gpiod_count(&pdev->dev, NULL) < 0)
+		return -ENODEV;
+
+	status = devm_acpi_dev_add_driver_gpios(&pdev->dev, shps_acpi_gpios);
+	if (status)
+		return status;
+
+	sdev = devm_kzalloc(&pdev->dev, sizeof(*sdev), GFP_KERNEL);
+	if (!sdev)
+		return -ENOMEM;
+
+	platform_set_drvdata(pdev, sdev);
+
+	/*
+	 * Initialize IRQs so that we can safely call surface_hotplug_remove()
+	 * on errors.
+	 */
+	for (i = 0; i < SHPS_NUM_IRQS; i++)
+		sdev->irq[i] = SHPS_IRQ_NOT_PRESENT;
+
+	/* Set up IRQs. */
+	for (i = 0; i < SHPS_NUM_IRQS; i++) {
+		mutex_init(&sdev->lock[i]);
+
+		status = shps_setup_irq(pdev, i);
+		if (status) {
+			dev_err(&pdev->dev, "failed to set up IRQ %d: %d\n", i, status);
+			goto err;
+		}
+	}
+
+	/* Ensure everything is up-to-date. */
+	for (i = 0; i < SHPS_NUM_IRQS; i++)
+		if (sdev->irq[i] != SHPS_IRQ_NOT_PRESENT)
+			shps_dsm_notify_irq(pdev, i);
+
+	return 0;
+
+err:
+	surface_hotplug_remove(pdev);
+	return status;
+}
+
+static const struct acpi_device_id surface_hotplug_acpi_match[] = {
+	{ "MSHW0153", 0 },
+	{ },
+};
+MODULE_DEVICE_TABLE(acpi, surface_hotplug_acpi_match);
+
+static struct platform_driver surface_hotplug_driver = {
+	.probe = surface_hotplug_probe,
+	.remove = surface_hotplug_remove,
+	.driver = {
+		.name = "surface_hotplug",
+		.acpi_match_table = surface_hotplug_acpi_match,
+		.probe_type = PROBE_PREFER_ASYNCHRONOUS,
+	},
+};
+module_platform_driver(surface_hotplug_driver);
+
+MODULE_AUTHOR("Maximilian Luz <luzmaximilian@gmail.com>");
+MODULE_DESCRIPTION("Surface Hot-Plug Signaling Driver for Surface Book Devices");
+MODULE_LICENSE("GPL");
-- 
2.30.1