4 files changed, 100 insertions, 0 deletions

diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile
index d94f92f88ca1..2a81d278bcf3 100644
--- a/drivers/acpi/Makefile
+++ b/drivers/acpi/Makefile
@@ -50,6 +50,7 @@ acpi-$(CONFIG_ACPI_REDUCED_HARDWARE_ONLY) += evged.o
 acpi-y                          += sysfs.o
 acpi-y                          += property.o
 acpi-$(CONFIG_X86)              += acpi_cmos_rtc.o
+acpi-$(CONFIG_X86)              += x86/utils.o
 acpi-$(CONFIG_DEBUG_FS)         += debugfs.o
 acpi-$(CONFIG_ACPI_NUMA)        += numa.o
 acpi-$(CONFIG_ACPI_PROCFS_POWER) += cm_sbs.o
diff --git a/drivers/acpi/bus.c b/drivers/acpi/bus.c
index 34fbe027e73a..784bda663d16 100644
--- a/drivers/acpi/bus.c
+++ b/drivers/acpi/bus.c
@@ -114,6 +114,11 @@ int acpi_bus_get_status(struct acpi_device *device)
         acpi_status status;
         unsigned long long sta;
 
+        if (acpi_device_always_present(device)) {
+                acpi_set_device_status(device, ACPI_STA_DEFAULT);
+                return 0;
+        }
+
         status = acpi_bus_get_status_handle(device->handle, &sta);
         if (ACPI_FAILURE(status))
                 return -ENODEV;
diff --git a/drivers/acpi/x86/utils.c b/drivers/acpi/x86/utils.c
new file mode 100644
index 000000000000..c8e90ef4485f
--- /dev/null
+++ b/drivers/acpi/x86/utils.c
@@ -0,0 +1,85 @@
+/*
+ * X86 ACPI Utility Functions
+ *
+ * Copyright (C) 2017 Hans de Goede <hdegoede@redhat.com>
+ *
+ * Based on various non upstream patches to support the CHT Whiskey Cove PMIC:
+ * Copyright (C) 2013-2015 Intel Corporation. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/acpi.h>
+#include <asm/cpu_device_id.h>
+#include <asm/intel-family.h>
+#include "../internal.h"
+
+/*
+ * Some ACPI devices are hidden (status == 0x0) in recent BIOS-es because
+ * some recent Windows drivers bind to one device but poke at multiple
+ * devices at the same time, so the others get hidden.
+ * We work around this by always reporting ACPI_STA_DEFAULT for these
+ * devices. Note this MUST only be done for devices where this is safe.
+ *
+ * This forcing of devices to be present is limited to specific CPU (SoC)
+ * models both to avoid potentially causing trouble on other models and
+ * because some HIDs are re-used on different SoCs for completely
+ * different devices.
+ */
+struct always_present_id {
+        struct acpi_device_id hid[2];
+        struct x86_cpu_id cpu_ids[2];
+        const char *uid;
+};
+
+#define ICPU(model)     { X86_VENDOR_INTEL, 6, model, X86_FEATURE_ANY, }
+
+#define ENTRY(hid, uid, cpu_models) {                                   \
+        { { hid, }, {} },                                               \
+        { cpu_models, {} },                                             \
+        uid,                                                            \
+}
+
+static const struct always_present_id always_present_ids[] = {
+        /*
+         * Bay / Cherry Trail PWM directly poked by GPU driver in win10,
+         * but Linux uses a separate PWM driver, harmless if not used.
+         */
+        ENTRY("80860F09", "1", ICPU(INTEL_FAM6_ATOM_SILVERMONT1)),
+        ENTRY("80862288", "1", ICPU(INTEL_FAM6_ATOM_AIRMONT)),
+};
+
+bool acpi_device_always_present(struct acpi_device *adev)
+{
+        u32 *status = (u32 *)&adev->status;
+        u32 old_status = *status;
+        bool ret = false;
+        unsigned int i;
+
+        /* acpi_match_device_ids checks status, so set it to default */
+        *status = ACPI_STA_DEFAULT;
+        for (i = 0; i < ARRAY_SIZE(always_present_ids); i++) {
+                if (acpi_match_device_ids(adev, always_present_ids[i].hid))
+                        continue;
+
+                if (!adev->pnp.unique_id ||
+                    strcmp(adev->pnp.unique_id, always_present_ids[i].uid))
+                        continue;
+
+                if (!x86_match_cpu(always_present_ids[i].cpu_ids))
+                        continue;
+
+                if (old_status != ACPI_STA_DEFAULT) /* Log only once */
+                        dev_info(&adev->dev,
+                                 "Device [%s] is in always present list\n",
+                                 adev->pnp.bus_id);
+
+                ret = true;
+                break;
+        }
+        *status = old_status;
+
+        return ret;
+}
diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h
index ef0ae8aaa567..b86b90489140 100644
--- a/include/acpi/acpi_bus.h
+++ b/include/acpi/acpi_bus.h
@@ -586,6 +586,15 @@ struct acpi_pci_root *acpi_pci_find_root(acpi_handle handle);
 int acpi_enable_wakeup_device_power(struct acpi_device *dev, int state);
 int acpi_disable_wakeup_device_power(struct acpi_device *dev);
 
+#ifdef CONFIG_X86
+bool acpi_device_always_present(struct acpi_device *adev);
+#else
+static inline bool acpi_device_always_present(struct acpi_device *adev)
+{
+        return false;
+}
+#endif
+
 #ifdef CONFIG_PM
 acpi_status acpi_add_pm_notifier(struct acpi_device *adev, struct device *dev,
                                  void (*work_func)(struct work_struct *work));