linux-surface/patches/5.10/0007-surface-hotplug.patch

From f255f201f64e16da9651393a9906956d6dcc89d7 Mon Sep 17 00:00:00 2001
From: Maximilian Luz <luzmaximilian@gmail.com>
Date: Sat, 31 Oct 2020 20:46:33 +0100
Subject: [PATCH] PCI: Add sysfs attribute for PCI device power state

While most PCI power-states can be queried from user-space via lspci,
this has some limits. Specifically, lspci fails to provide an accurate
value when the device is in D3cold as it has to resume the device before
it can access its power state via the configuration space, leading to it
reporting D0 or another on-state. Thus lspci can, for example, not be
used to diagnose power-consumption issues for devices that can enter
D3cold or to ensure that devices properly enter D3cold at all.

To alleviate this issue, introduce a new sysfs device attribute for the
PCI power state, showing the current power state as seen by the kernel.

Signed-off-by: Maximilian Luz <luzmaximilian@gmail.com>
Patchset: surface-hotplug
---
 Documentation/ABI/testing/sysfs-bus-pci |  9 +++++++++
 drivers/pci/pci-sysfs.c                 | 12 ++++++++++++
 2 files changed, 21 insertions(+)

diff --git a/Documentation/ABI/testing/sysfs-bus-pci b/Documentation/ABI/testing/sysfs-bus-pci
index 77ad9ec3c801..25c9c39770c6 100644
--- a/Documentation/ABI/testing/sysfs-bus-pci
+++ b/Documentation/ABI/testing/sysfs-bus-pci
@@ -366,3 +366,12 @@ Contact:	Heiner Kallweit <hkallweit1@gmail.com>
 Description:	If ASPM is supported for an endpoint, these files can be
 		used to disable or enable the individual power management
 		states. Write y/1/on to enable, n/0/off to disable.
+
+What:		/sys/bus/pci/devices/.../power_state
+Date:		November 2020
+Contact:	Linux PCI developers <linux-pci@vger.kernel.org>
+Description:
+		This file contains the current PCI power state of the device.
+		The value comes from the PCI kernel device state and can be one
+		of: "unknown", "error", "D0", D1", "D2", "D3hot", "D3cold".
+		The file is read only.
diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
index d15c881e2e7e..b15f754e6346 100644
--- a/drivers/pci/pci-sysfs.c
+++ b/drivers/pci/pci-sysfs.c
@@ -124,6 +124,17 @@ static ssize_t cpulistaffinity_show(struct device *dev,
 }
 static DEVICE_ATTR_RO(cpulistaffinity);
 
+/* PCI power state */
+static ssize_t power_state_show(struct device *dev,
+				struct device_attribute *attr, char *buf)
+{
+	struct pci_dev *pci_dev = to_pci_dev(dev);
+	pci_power_t state = READ_ONCE(pci_dev->current_state);
+
+	return sprintf(buf, "%s\n", pci_power_name(state));
+}
+static DEVICE_ATTR_RO(power_state);
+
 /* show resources */
 static ssize_t resource_show(struct device *dev, struct device_attribute *attr,
 			     char *buf)
@@ -581,6 +592,7 @@ static ssize_t driver_override_show(struct device *dev,
 static DEVICE_ATTR_RW(driver_override);
 
 static struct attribute *pci_dev_attrs[] = {
+	&dev_attr_power_state.attr,
 	&dev_attr_resource.attr,
 	&dev_attr_vendor.attr,
 	&dev_attr_device.attr,
-- 
2.33.0

From cd1bedb6ac1c78f328d474774dcdaabdc385c409 Mon Sep 17 00:00:00 2001
From: Maximilian Luz <luzmaximilian@gmail.com>
Date: Mon, 14 Dec 2020 20:50:59 +0100
Subject: [PATCH] platform/x86: Add Surface Hotplug driver

Add a driver to handle out-of-band hot-plug signaling for the discrete
GPU (dGPU) on Microsoft Surface Book 2 and 3 devices. This driver is
required to properly detect hot-plugging of the dGPU and relay the
appropriate signal to the PCIe hot-plug driver core.

Signed-off-by: Maximilian Luz <luzmaximilian@gmail.com>
Patchset: surface-hotplug
---
 drivers/platform/x86/Kconfig           |  20 ++
 drivers/platform/x86/Makefile          |   1 +
 drivers/platform/x86/surface_hotplug.c | 282 +++++++++++++++++++++++++
 3 files changed, 303 insertions(+)
 create mode 100644 drivers/platform/x86/surface_hotplug.c

diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig
index d44d3fb9ca72..533998040530 100644
--- a/drivers/platform/x86/Kconfig
+++ b/drivers/platform/x86/Kconfig
@@ -1012,6 +1012,26 @@ 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 System Driver"
+	depends on ACPI
+	default m
+	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_BOOK1_DGPU_SWITCH
 	tristate "Surface Book 1 dGPU Switch Driver"
 	depends on ACPI && SYSFS
diff --git a/drivers/platform/x86/Makefile b/drivers/platform/x86/Makefile
index 2e0a2896c78d..f552cbfb7914 100644
--- a/drivers/platform/x86/Makefile
+++ b/drivers/platform/x86/Makefile
@@ -94,6 +94,7 @@ obj-$(CONFIG_SURFACE_3_BUTTON)		+= surface3_button.o
 obj-$(CONFIG_SURFACE_3_POWER_OPREGION)	+= surface3_power.o
 obj-$(CONFIG_SURFACE_PRO3_BUTTON)	+= surfacepro3_button.o
 obj-$(CONFIG_SURFACE_GPE)		+= surface_gpe.o
+obj-$(CONFIG_SURFACE_HOTPLUG)		+= surface_hotplug.o
 obj-$(CONFIG_SURFACE_BOOK1_DGPU_SWITCH)	+= sb1_dgpu_sw.o
 
 # MSI
diff --git a/drivers/platform/x86/surface_hotplug.c b/drivers/platform/x86/surface_hotplug.c
new file mode 100644
index 000000000000..cfcc15cfbacb
--- /dev/null
+++ b/drivers/platform/x86/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");
-- 
2.33.0

From 4a19147e3089c339a35adf8babad555cda52cb2e Mon Sep 17 00:00:00 2001
From: Maximilian Luz <luzmaximilian@gmail.com>
Date: Fri, 2 Jul 2021 14:35:43 +0200
Subject: [PATCH] Revert "Revert "PCI: PM: Do not read power state in
 pci_enable_device_flags()""

This reverts commit f11f9ff8a7c97b2a3990c7322304627d9b58d362.

Patchset: surface-hotplug
---
 drivers/pci/pci.c | 16 +++-------------
 1 file changed, 3 insertions(+), 13 deletions(-)

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 29f5d699fa06..c73fcdff0c16 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -1874,20 +1874,10 @@ static int pci_enable_device_flags(struct pci_dev *dev, unsigned long flags)
 	int err;
 	int i, bars = 0;
 
-	/*
-	 * Power state could be unknown at this point, either due to a fresh
-	 * boot or a device removal call.  So get the current power state
-	 * so that things like MSI message writing will behave as expected
-	 * (e.g. if the device really is in D0 at enable time).
-	 */
-	if (dev->pm_cap) {
-		u16 pmcsr;
-		pci_read_config_word(dev, dev->pm_cap + PCI_PM_CTRL, &pmcsr);
-		dev->current_state = (pmcsr & PCI_PM_CTRL_STATE_MASK);
-	}
-
-	if (atomic_inc_return(&dev->enable_cnt) > 1)
+	if (atomic_inc_return(&dev->enable_cnt) > 1) {
+		pci_update_current_state(dev, dev->current_state);
 		return 0;		/* already enabled */
+	}
 
 	bridge = pci_upstream_bridge(dev);
 	if (bridge)
-- 
2.33.0