// 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) 2019-2022 Maximilian Luz <[email protected]>
*/
#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_typed(handle, &shps_dsm_guid, SHPS_DSM_REVISION,
shps_dsm_fn_for_irq(type), ¶m, ACPI_TYPE_BUFFER);
if (!result) {
dev_err(&pdev->dev, "IRQ notification via DSM failed (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]);
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 void 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]);
}
}
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_new = 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 <[email protected]>");
MODULE_DESCRIPTION("Surface Hot-Plug Signaling Driver for Surface Book Devices");
MODULE_LICENSE("GPL");
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