283 lines
8.1 KiB
C
283 lines
8.1 KiB
C
// 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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#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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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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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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/* 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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#define SHPS_DSM_REVISION 1
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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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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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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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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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#define SHPS_IRQ_NOT_PRESENT ((unsigned int)-1)
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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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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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mutex_lock(&sdev->lock[type]);
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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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dev_dbg(&pdev->dev, "IRQ notification via DSM (irq=%d, value=%d)\n", type, value);
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param.type = ACPI_TYPE_INTEGER;
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param.integer.value = value;
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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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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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} 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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} 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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mutex_unlock(&sdev->lock[type]);
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if (result)
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ACPI_FREE(result);
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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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/* 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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/* 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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/* 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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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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* 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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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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irq = gpiod_to_irq(gpiod);
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if (irq < 0)
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return irq;
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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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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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dev_dbg(&pdev->dev, "set up irq %d as type %d\n", irq, type);
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sdev->gpio[type] = gpiod;
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sdev->irq[type] = irq;
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return 0;
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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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/* 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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mutex_destroy(&sdev->lock[i]);
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}
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return 0;
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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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* 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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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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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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platform_set_drvdata(pdev, sdev);
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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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/* 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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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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/* 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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return 0;
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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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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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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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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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