99543a73db
Changes: - SAM: - Add support for the 13" Intel version of the Surface Laptop 4 - Small code cleanup Links: - kernel:fbe1313c9b
- SAM:e24239cf87
387 lines
13 KiB
Diff
387 lines
13 KiB
Diff
From cd52292158d7d66780db63a93606d7ba6a84e96d Mon Sep 17 00:00:00 2001
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From: Maximilian Luz <luzmaximilian@gmail.com>
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Date: Fri, 5 Feb 2021 02:26:57 +0100
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Subject: [PATCH] platform/surface: Add Surface Hot-Plug driver
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Some Surface Book 2 and 3 models have a discrete GPU (dGPU) that is
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hot-pluggable. On those devices, the dGPU is contained in the base,
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which can be separated from the tablet part (containing CPU and
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touchscreen) while the device is running.
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It (in general) is presented as/behaves like a standard PCIe hot-plug
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capable device, however, this device can also be put into D3cold. In
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D3cold, the device itself is turned off and can thus not submit any
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standard PCIe hot-plug events. To properly detect hot-(un)plugging while
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the dGPU is in D3cold, out-of-band signaling is required. Without this,
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the device state will only get updated during the next bus-check, eg.
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via a manually issued lspci call.
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This commit adds a driver to handle out-of-band PCIe hot-(un)plug events
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on Microsoft Surface devices. On those devices, said events can be
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detected via GPIO interrupts, which are then forwarded to the
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corresponding ACPI DSM calls by this driver. The DSM then takes care of
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issuing the appropriate bus-/device-check, causing the PCI core to
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properly pick up the device change.
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Signed-off-by: Maximilian Luz <luzmaximilian@gmail.com>
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Link: https://lore.kernel.org/r/20210205012657.1951753-1-luzmaximilian@gmail.com
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Signed-off-by: Hans de Goede <hdegoede@redhat.com>
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Patchset: surface-hotplug
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---
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MAINTAINERS | 6 +
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drivers/platform/surface/Kconfig | 19 ++
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drivers/platform/surface/Makefile | 1 +
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drivers/platform/surface/surface_hotplug.c | 282 +++++++++++++++++++++
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4 files changed, 308 insertions(+)
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create mode 100644 drivers/platform/surface/surface_hotplug.c
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diff --git a/MAINTAINERS b/MAINTAINERS
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index 3d57740df499..d1b36e222cd1 100644
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--- a/MAINTAINERS
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+++ b/MAINTAINERS
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@@ -11823,6 +11823,12 @@ L: platform-driver-x86@vger.kernel.org
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S: Maintained
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F: drivers/hid/surface-hid/
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+MICROSOFT SURFACE HOT-PLUG DRIVER
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+M: Maximilian Luz <luzmaximilian@gmail.com>
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+L: platform-driver-x86@vger.kernel.org
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+S: Maintained
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+F: drivers/platform/surface/surface_hotplug.c
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+
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MICROSOFT SURFACE PRO 3 BUTTON DRIVER
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M: Chen Yu <yu.c.chen@intel.com>
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L: platform-driver-x86@vger.kernel.org
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diff --git a/drivers/platform/surface/Kconfig b/drivers/platform/surface/Kconfig
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index 3ceeb316d56e..2784a480f310 100644
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--- a/drivers/platform/surface/Kconfig
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+++ b/drivers/platform/surface/Kconfig
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@@ -140,6 +140,25 @@ config SURFACE_GPE
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accordingly. It is required on those devices to allow wake-ups from
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suspend by opening the lid.
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+config SURFACE_HOTPLUG
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+ tristate "Surface Hot-Plug Driver"
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+ depends on GPIOLIB
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+ help
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+ Driver for out-of-band hot-plug event signaling on Microsoft Surface
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+ devices with hot-pluggable PCIe cards.
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+
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+ This driver is used on Surface Book (2 and 3) devices with a
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+ hot-pluggable discrete GPU (dGPU). When not in use, the dGPU on those
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+ devices can enter D3cold, which prevents in-band (standard) PCIe
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+ hot-plug signaling. Thus, without this driver, detaching the base
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+ containing the dGPU will not correctly update the state of the
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+ corresponding PCIe device if it is in D3cold. This driver adds support
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+ for out-of-band hot-plug notifications, ensuring that the device state
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+ is properly updated even when the device in question is in D3cold.
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+
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+ Select M or Y here, if you want to (fully) support hot-plugging of
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+ dGPU devices on the Surface Book 2 and/or 3 during D3cold.
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+
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config SURFACE_PERFMODE
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tristate "Surface Performance-Mode Driver"
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depends on SURFACE_AGGREGATOR_BUS
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diff --git a/drivers/platform/surface/Makefile b/drivers/platform/surface/Makefile
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index 31098983decc..a103fdb3ef1a 100644
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--- a/drivers/platform/surface/Makefile
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+++ b/drivers/platform/surface/Makefile
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@@ -14,5 +14,6 @@ obj-$(CONFIG_SURFACE_AGGREGATOR_REGISTRY) += surface_aggregator_registry.o
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obj-$(CONFIG_SURFACE_BOOK1_DGPU_SWITCH) += surfacebook1_dgpu_switch.o
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obj-$(CONFIG_SURFACE_DTX) += surface_dtx.o
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obj-$(CONFIG_SURFACE_GPE) += surface_gpe.o
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+obj-$(CONFIG_SURFACE_HOTPLUG) += surface_hotplug.o
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obj-$(CONFIG_SURFACE_PERFMODE) += surface_perfmode.o
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obj-$(CONFIG_SURFACE_PRO3_BUTTON) += surfacepro3_button.o
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diff --git a/drivers/platform/surface/surface_hotplug.c b/drivers/platform/surface/surface_hotplug.c
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new file mode 100644
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index 000000000000..cfcc15cfbacb
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--- /dev/null
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+++ b/drivers/platform/surface/surface_hotplug.c
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@@ -0,0 +1,282 @@
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+// SPDX-License-Identifier: GPL-2.0+
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+/*
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+ * Surface Book (2 and later) hot-plug driver.
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+ *
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+ * Surface Book devices (can) have a hot-pluggable discrete GPU (dGPU). This
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+ * driver is responsible for out-of-band hot-plug event signaling on these
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+ * devices. It is specifically required when the hot-plug device is in D3cold
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+ * and can thus not generate PCIe hot-plug events itself.
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+ *
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+ * Event signaling is handled via ACPI, which will generate the appropriate
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+ * device-check notifications to be picked up by the PCIe hot-plug driver.
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+ *
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+ * Copyright (C) 2019-2021 Maximilian Luz <luzmaximilian@gmail.com>
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+ */
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+
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+#include <linux/acpi.h>
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+#include <linux/gpio.h>
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+#include <linux/interrupt.h>
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+#include <linux/kernel.h>
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+#include <linux/module.h>
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+#include <linux/mutex.h>
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+#include <linux/platform_device.h>
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+
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+static const struct acpi_gpio_params shps_base_presence_int = { 0, 0, false };
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+static const struct acpi_gpio_params shps_base_presence = { 1, 0, false };
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+static const struct acpi_gpio_params shps_device_power_int = { 2, 0, false };
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+static const struct acpi_gpio_params shps_device_power = { 3, 0, false };
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+static const struct acpi_gpio_params shps_device_presence_int = { 4, 0, false };
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+static const struct acpi_gpio_params shps_device_presence = { 5, 0, false };
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+
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+static const struct acpi_gpio_mapping shps_acpi_gpios[] = {
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+ { "base_presence-int-gpio", &shps_base_presence_int, 1 },
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+ { "base_presence-gpio", &shps_base_presence, 1 },
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+ { "device_power-int-gpio", &shps_device_power_int, 1 },
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+ { "device_power-gpio", &shps_device_power, 1 },
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+ { "device_presence-int-gpio", &shps_device_presence_int, 1 },
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+ { "device_presence-gpio", &shps_device_presence, 1 },
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+ { },
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+};
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+
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+/* 5515a847-ed55-4b27-8352-cd320e10360a */
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+static const guid_t shps_dsm_guid =
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+ GUID_INIT(0x5515a847, 0xed55, 0x4b27, 0x83, 0x52, 0xcd, 0x32, 0x0e, 0x10, 0x36, 0x0a);
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+
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+#define SHPS_DSM_REVISION 1
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+
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+enum shps_dsm_fn {
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+ SHPS_DSM_FN_PCI_NUM_ENTRIES = 0x01,
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+ SHPS_DSM_FN_PCI_GET_ENTRIES = 0x02,
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+ SHPS_DSM_FN_IRQ_BASE_PRESENCE = 0x03,
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+ SHPS_DSM_FN_IRQ_DEVICE_POWER = 0x04,
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+ SHPS_DSM_FN_IRQ_DEVICE_PRESENCE = 0x05,
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+};
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+
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+enum shps_irq_type {
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+ /* NOTE: Must be in order of enum shps_dsm_fn above. */
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+ SHPS_IRQ_TYPE_BASE_PRESENCE = 0,
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+ SHPS_IRQ_TYPE_DEVICE_POWER = 1,
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+ SHPS_IRQ_TYPE_DEVICE_PRESENCE = 2,
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+ SHPS_NUM_IRQS,
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+};
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+
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+static const char *const shps_gpio_names[] = {
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+ [SHPS_IRQ_TYPE_BASE_PRESENCE] = "base_presence",
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+ [SHPS_IRQ_TYPE_DEVICE_POWER] = "device_power",
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+ [SHPS_IRQ_TYPE_DEVICE_PRESENCE] = "device_presence",
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+};
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+
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+struct shps_device {
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+ struct mutex lock[SHPS_NUM_IRQS]; /* Protects update in shps_dsm_notify_irq() */
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+ struct gpio_desc *gpio[SHPS_NUM_IRQS];
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+ unsigned int irq[SHPS_NUM_IRQS];
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+};
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+
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+#define SHPS_IRQ_NOT_PRESENT ((unsigned int)-1)
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+
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+static enum shps_dsm_fn shps_dsm_fn_for_irq(enum shps_irq_type type)
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+{
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+ return SHPS_DSM_FN_IRQ_BASE_PRESENCE + type;
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+}
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+
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+static void shps_dsm_notify_irq(struct platform_device *pdev, enum shps_irq_type type)
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+{
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+ struct shps_device *sdev = platform_get_drvdata(pdev);
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+ acpi_handle handle = ACPI_HANDLE(&pdev->dev);
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+ union acpi_object *result;
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+ union acpi_object param;
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+ int value;
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+
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+ mutex_lock(&sdev->lock[type]);
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+
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+ value = gpiod_get_value_cansleep(sdev->gpio[type]);
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+ if (value < 0) {
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+ mutex_unlock(&sdev->lock[type]);
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+ dev_err(&pdev->dev, "failed to get gpio: %d (irq=%d)\n", type, value);
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+ return;
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+ }
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+
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+ dev_dbg(&pdev->dev, "IRQ notification via DSM (irq=%d, value=%d)\n", type, value);
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+
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+ param.type = ACPI_TYPE_INTEGER;
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+ param.integer.value = value;
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+
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+ result = acpi_evaluate_dsm(handle, &shps_dsm_guid, SHPS_DSM_REVISION,
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+ shps_dsm_fn_for_irq(type), ¶m);
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+
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+ if (!result) {
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+ dev_err(&pdev->dev, "IRQ notification via DSM failed (irq=%d, gpio=%d)\n",
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+ type, value);
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+
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+ } else if (result->type != ACPI_TYPE_BUFFER) {
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+ dev_err(&pdev->dev,
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+ "IRQ notification via DSM failed: unexpected result type (irq=%d, gpio=%d)\n",
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+ type, value);
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+
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+ } else if (result->buffer.length != 1 || result->buffer.pointer[0] != 0) {
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+ dev_err(&pdev->dev,
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+ "IRQ notification via DSM failed: unexpected result value (irq=%d, gpio=%d)\n",
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+ type, value);
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+ }
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+
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+ mutex_unlock(&sdev->lock[type]);
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+
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+ if (result)
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+ ACPI_FREE(result);
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+}
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+
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+static irqreturn_t shps_handle_irq(int irq, void *data)
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+{
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+ struct platform_device *pdev = data;
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+ struct shps_device *sdev = platform_get_drvdata(pdev);
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+ int type;
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+
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+ /* Figure out which IRQ we're handling. */
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+ for (type = 0; type < SHPS_NUM_IRQS; type++)
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+ if (irq == sdev->irq[type])
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+ break;
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+
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+ /* We should have found our interrupt, if not: this is a bug. */
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+ if (WARN(type >= SHPS_NUM_IRQS, "invalid IRQ number: %d\n", irq))
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+ return IRQ_HANDLED;
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+
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+ /* Forward interrupt to ACPI via DSM. */
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+ shps_dsm_notify_irq(pdev, type);
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+ return IRQ_HANDLED;
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+}
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+
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+static int shps_setup_irq(struct platform_device *pdev, enum shps_irq_type type)
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+{
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+ unsigned long flags = IRQF_ONESHOT | IRQF_TRIGGER_FALLING | IRQF_TRIGGER_RISING;
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+ struct shps_device *sdev = platform_get_drvdata(pdev);
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+ struct gpio_desc *gpiod;
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+ acpi_handle handle = ACPI_HANDLE(&pdev->dev);
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+ const char *irq_name;
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+ const int dsm = shps_dsm_fn_for_irq(type);
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+ int status, irq;
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+
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+ /*
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+ * Only set up interrupts that we actually need: The Surface Book 3
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+ * does not have a DSM for base presence, so don't set up an interrupt
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+ * for that.
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+ */
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+ if (!acpi_check_dsm(handle, &shps_dsm_guid, SHPS_DSM_REVISION, BIT(dsm))) {
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+ dev_dbg(&pdev->dev, "IRQ notification via DSM not present (irq=%d)\n", type);
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+ return 0;
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+ }
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+
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+ gpiod = devm_gpiod_get(&pdev->dev, shps_gpio_names[type], GPIOD_ASIS);
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+ if (IS_ERR(gpiod))
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+ return PTR_ERR(gpiod);
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+
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+ irq = gpiod_to_irq(gpiod);
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+ if (irq < 0)
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+ return irq;
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+
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+ irq_name = devm_kasprintf(&pdev->dev, GFP_KERNEL, "shps-irq-%d", type);
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+ if (!irq_name)
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+ return -ENOMEM;
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+
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+ status = devm_request_threaded_irq(&pdev->dev, irq, NULL, shps_handle_irq,
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+ flags, irq_name, pdev);
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+ if (status)
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+ return status;
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+
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+ dev_dbg(&pdev->dev, "set up irq %d as type %d\n", irq, type);
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+
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+ sdev->gpio[type] = gpiod;
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+ sdev->irq[type] = irq;
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+
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+ return 0;
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+}
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+
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+static int surface_hotplug_remove(struct platform_device *pdev)
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+{
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+ struct shps_device *sdev = platform_get_drvdata(pdev);
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+ int i;
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+
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+ /* Ensure that IRQs have been fully handled and won't trigger any more. */
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+ for (i = 0; i < SHPS_NUM_IRQS; i++) {
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+ if (sdev->irq[i] != SHPS_IRQ_NOT_PRESENT)
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+ disable_irq(sdev->irq[i]);
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+
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+ mutex_destroy(&sdev->lock[i]);
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+ }
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+
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+ return 0;
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+}
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+
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+static int surface_hotplug_probe(struct platform_device *pdev)
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+{
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+ struct shps_device *sdev;
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+ int status, i;
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+
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+ /*
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+ * The MSHW0153 device is also present on the Surface Laptop 3,
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+ * however that doesn't have a hot-pluggable PCIe device. It also
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+ * doesn't have any GPIO interrupts/pins under the MSHW0153, so filter
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+ * it out here.
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+ */
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+ if (gpiod_count(&pdev->dev, NULL) < 0)
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+ return -ENODEV;
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+
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+ status = devm_acpi_dev_add_driver_gpios(&pdev->dev, shps_acpi_gpios);
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+ if (status)
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+ return status;
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+
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+ sdev = devm_kzalloc(&pdev->dev, sizeof(*sdev), GFP_KERNEL);
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+ if (!sdev)
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+ return -ENOMEM;
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+
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+ platform_set_drvdata(pdev, sdev);
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+
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+ /*
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+ * Initialize IRQs so that we can safely call surface_hotplug_remove()
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+ * on errors.
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+ */
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+ for (i = 0; i < SHPS_NUM_IRQS; i++)
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+ sdev->irq[i] = SHPS_IRQ_NOT_PRESENT;
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+
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+ /* Set up IRQs. */
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+ for (i = 0; i < SHPS_NUM_IRQS; i++) {
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+ mutex_init(&sdev->lock[i]);
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+
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+ status = shps_setup_irq(pdev, i);
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+ if (status) {
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+ dev_err(&pdev->dev, "failed to set up IRQ %d: %d\n", i, status);
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+ goto err;
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+ }
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+ }
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+
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+ /* Ensure everything is up-to-date. */
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+ for (i = 0; i < SHPS_NUM_IRQS; i++)
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+ if (sdev->irq[i] != SHPS_IRQ_NOT_PRESENT)
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+ shps_dsm_notify_irq(pdev, i);
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+
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+ return 0;
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+
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+err:
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+ surface_hotplug_remove(pdev);
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+ return status;
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+}
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+
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+static const struct acpi_device_id surface_hotplug_acpi_match[] = {
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+ { "MSHW0153", 0 },
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+ { },
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+};
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+MODULE_DEVICE_TABLE(acpi, surface_hotplug_acpi_match);
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+
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+static struct platform_driver surface_hotplug_driver = {
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+ .probe = surface_hotplug_probe,
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+ .remove = surface_hotplug_remove,
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+ .driver = {
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+ .name = "surface_hotplug",
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+ .acpi_match_table = surface_hotplug_acpi_match,
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+ .probe_type = PROBE_PREFER_ASYNCHRONOUS,
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+ },
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+};
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+module_platform_driver(surface_hotplug_driver);
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+
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+MODULE_AUTHOR("Maximilian Luz <luzmaximilian@gmail.com>");
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+MODULE_DESCRIPTION("Surface Hot-Plug Signaling Driver for Surface Book Devices");
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+MODULE_LICENSE("GPL");
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--
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2.31.1
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