1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3 * Surface Book (2 and later) hot-plug driver.
4 *
5 * Surface Book devices (can) have a hot-pluggable discrete GPU (dGPU). This
6 * driver is responsible for out-of-band hot-plug event signaling on these
7 * devices. It is specifically required when the hot-plug device is in D3cold
8 * and can thus not generate PCIe hot-plug events itself.
9 *
10 * Event signaling is handled via ACPI, which will generate the appropriate
11 * device-check notifications to be picked up by the PCIe hot-plug driver.
12 *
13 * Copyright (C) 2019-2022 Maximilian Luz <luzmaximilian@gmail.com>
14 */
15
16 #include <linux/acpi.h>
17 #include <linux/gpio.h>
18 #include <linux/interrupt.h>
19 #include <linux/kernel.h>
20 #include <linux/module.h>
21 #include <linux/mutex.h>
22 #include <linux/platform_device.h>
23
24 static const struct acpi_gpio_params shps_base_presence_int = { 0, 0, false };
25 static const struct acpi_gpio_params shps_base_presence = { 1, 0, false };
26 static const struct acpi_gpio_params shps_device_power_int = { 2, 0, false };
27 static const struct acpi_gpio_params shps_device_power = { 3, 0, false };
28 static const struct acpi_gpio_params shps_device_presence_int = { 4, 0, false };
29 static const struct acpi_gpio_params shps_device_presence = { 5, 0, false };
30
31 static const struct acpi_gpio_mapping shps_acpi_gpios[] = {
32 { "base_presence-int-gpio", &shps_base_presence_int, 1 },
33 { "base_presence-gpio", &shps_base_presence, 1 },
34 { "device_power-int-gpio", &shps_device_power_int, 1 },
35 { "device_power-gpio", &shps_device_power, 1 },
36 { "device_presence-int-gpio", &shps_device_presence_int, 1 },
37 { "device_presence-gpio", &shps_device_presence, 1 },
38 { },
39 };
40
41 /* 5515a847-ed55-4b27-8352-cd320e10360a */
42 static const guid_t shps_dsm_guid =
43 GUID_INIT(0x5515a847, 0xed55, 0x4b27, 0x83, 0x52, 0xcd, 0x32, 0x0e, 0x10, 0x36, 0x0a);
44
45 #define SHPS_DSM_REVISION 1
46
47 enum shps_dsm_fn {
48 SHPS_DSM_FN_PCI_NUM_ENTRIES = 0x01,
49 SHPS_DSM_FN_PCI_GET_ENTRIES = 0x02,
50 SHPS_DSM_FN_IRQ_BASE_PRESENCE = 0x03,
51 SHPS_DSM_FN_IRQ_DEVICE_POWER = 0x04,
52 SHPS_DSM_FN_IRQ_DEVICE_PRESENCE = 0x05,
53 };
54
55 enum shps_irq_type {
56 /* NOTE: Must be in order of enum shps_dsm_fn above. */
57 SHPS_IRQ_TYPE_BASE_PRESENCE = 0,
58 SHPS_IRQ_TYPE_DEVICE_POWER = 1,
59 SHPS_IRQ_TYPE_DEVICE_PRESENCE = 2,
60 SHPS_NUM_IRQS,
61 };
62
63 static const char *const shps_gpio_names[] = {
64 [SHPS_IRQ_TYPE_BASE_PRESENCE] = "base_presence",
65 [SHPS_IRQ_TYPE_DEVICE_POWER] = "device_power",
66 [SHPS_IRQ_TYPE_DEVICE_PRESENCE] = "device_presence",
67 };
68
69 struct shps_device {
70 struct mutex lock[SHPS_NUM_IRQS]; /* Protects update in shps_dsm_notify_irq() */
71 struct gpio_desc *gpio[SHPS_NUM_IRQS];
72 unsigned int irq[SHPS_NUM_IRQS];
73 };
74
75 #define SHPS_IRQ_NOT_PRESENT ((unsigned int)-1)
76
shps_dsm_fn_for_irq(enum shps_irq_type type)77 static enum shps_dsm_fn shps_dsm_fn_for_irq(enum shps_irq_type type)
78 {
79 return SHPS_DSM_FN_IRQ_BASE_PRESENCE + type;
80 }
81
shps_dsm_notify_irq(struct platform_device * pdev,enum shps_irq_type type)82 static void shps_dsm_notify_irq(struct platform_device *pdev, enum shps_irq_type type)
83 {
84 struct shps_device *sdev = platform_get_drvdata(pdev);
85 acpi_handle handle = ACPI_HANDLE(&pdev->dev);
86 union acpi_object *result;
87 union acpi_object param;
88 int value;
89
90 mutex_lock(&sdev->lock[type]);
91
92 value = gpiod_get_value_cansleep(sdev->gpio[type]);
93 if (value < 0) {
94 mutex_unlock(&sdev->lock[type]);
95 dev_err(&pdev->dev, "failed to get gpio: %d (irq=%d)\n", type, value);
96 return;
97 }
98
99 dev_dbg(&pdev->dev, "IRQ notification via DSM (irq=%d, value=%d)\n", type, value);
100
101 param.type = ACPI_TYPE_INTEGER;
102 param.integer.value = value;
103
104 result = acpi_evaluate_dsm_typed(handle, &shps_dsm_guid, SHPS_DSM_REVISION,
105 shps_dsm_fn_for_irq(type), ¶m, ACPI_TYPE_BUFFER);
106 if (!result) {
107 dev_err(&pdev->dev, "IRQ notification via DSM failed (irq=%d, gpio=%d)\n",
108 type, value);
109
110 } else if (result->buffer.length != 1 || result->buffer.pointer[0] != 0) {
111 dev_err(&pdev->dev,
112 "IRQ notification via DSM failed: unexpected result value (irq=%d, gpio=%d)\n",
113 type, value);
114 }
115
116 mutex_unlock(&sdev->lock[type]);
117
118 ACPI_FREE(result);
119 }
120
shps_handle_irq(int irq,void * data)121 static irqreturn_t shps_handle_irq(int irq, void *data)
122 {
123 struct platform_device *pdev = data;
124 struct shps_device *sdev = platform_get_drvdata(pdev);
125 int type;
126
127 /* Figure out which IRQ we're handling. */
128 for (type = 0; type < SHPS_NUM_IRQS; type++)
129 if (irq == sdev->irq[type])
130 break;
131
132 /* We should have found our interrupt, if not: this is a bug. */
133 if (WARN(type >= SHPS_NUM_IRQS, "invalid IRQ number: %d\n", irq))
134 return IRQ_HANDLED;
135
136 /* Forward interrupt to ACPI via DSM. */
137 shps_dsm_notify_irq(pdev, type);
138 return IRQ_HANDLED;
139 }
140
shps_setup_irq(struct platform_device * pdev,enum shps_irq_type type)141 static int shps_setup_irq(struct platform_device *pdev, enum shps_irq_type type)
142 {
143 unsigned long flags = IRQF_ONESHOT | IRQF_TRIGGER_FALLING | IRQF_TRIGGER_RISING;
144 struct shps_device *sdev = platform_get_drvdata(pdev);
145 struct gpio_desc *gpiod;
146 acpi_handle handle = ACPI_HANDLE(&pdev->dev);
147 const char *irq_name;
148 const int dsm = shps_dsm_fn_for_irq(type);
149 int status, irq;
150
151 /*
152 * Only set up interrupts that we actually need: The Surface Book 3
153 * does not have a DSM for base presence, so don't set up an interrupt
154 * for that.
155 */
156 if (!acpi_check_dsm(handle, &shps_dsm_guid, SHPS_DSM_REVISION, BIT(dsm))) {
157 dev_dbg(&pdev->dev, "IRQ notification via DSM not present (irq=%d)\n", type);
158 return 0;
159 }
160
161 gpiod = devm_gpiod_get(&pdev->dev, shps_gpio_names[type], GPIOD_ASIS);
162 if (IS_ERR(gpiod))
163 return PTR_ERR(gpiod);
164
165 irq = gpiod_to_irq(gpiod);
166 if (irq < 0)
167 return irq;
168
169 irq_name = devm_kasprintf(&pdev->dev, GFP_KERNEL, "shps-irq-%d", type);
170 if (!irq_name)
171 return -ENOMEM;
172
173 status = devm_request_threaded_irq(&pdev->dev, irq, NULL, shps_handle_irq,
174 flags, irq_name, pdev);
175 if (status)
176 return status;
177
178 dev_dbg(&pdev->dev, "set up irq %d as type %d\n", irq, type);
179
180 sdev->gpio[type] = gpiod;
181 sdev->irq[type] = irq;
182
183 return 0;
184 }
185
surface_hotplug_remove(struct platform_device * pdev)186 static void surface_hotplug_remove(struct platform_device *pdev)
187 {
188 struct shps_device *sdev = platform_get_drvdata(pdev);
189 int i;
190
191 /* Ensure that IRQs have been fully handled and won't trigger any more. */
192 for (i = 0; i < SHPS_NUM_IRQS; i++) {
193 if (sdev->irq[i] != SHPS_IRQ_NOT_PRESENT)
194 disable_irq(sdev->irq[i]);
195
196 mutex_destroy(&sdev->lock[i]);
197 }
198 }
199
surface_hotplug_probe(struct platform_device * pdev)200 static int surface_hotplug_probe(struct platform_device *pdev)
201 {
202 struct shps_device *sdev;
203 int status, i;
204
205 /*
206 * The MSHW0153 device is also present on the Surface Laptop 3,
207 * however that doesn't have a hot-pluggable PCIe device. It also
208 * doesn't have any GPIO interrupts/pins under the MSHW0153, so filter
209 * it out here.
210 */
211 if (gpiod_count(&pdev->dev, NULL) < 0)
212 return -ENODEV;
213
214 status = devm_acpi_dev_add_driver_gpios(&pdev->dev, shps_acpi_gpios);
215 if (status)
216 return status;
217
218 sdev = devm_kzalloc(&pdev->dev, sizeof(*sdev), GFP_KERNEL);
219 if (!sdev)
220 return -ENOMEM;
221
222 platform_set_drvdata(pdev, sdev);
223
224 /*
225 * Initialize IRQs so that we can safely call surface_hotplug_remove()
226 * on errors.
227 */
228 for (i = 0; i < SHPS_NUM_IRQS; i++)
229 sdev->irq[i] = SHPS_IRQ_NOT_PRESENT;
230
231 /* Set up IRQs. */
232 for (i = 0; i < SHPS_NUM_IRQS; i++) {
233 mutex_init(&sdev->lock[i]);
234
235 status = shps_setup_irq(pdev, i);
236 if (status) {
237 dev_err(&pdev->dev, "failed to set up IRQ %d: %d\n", i, status);
238 goto err;
239 }
240 }
241
242 /* Ensure everything is up-to-date. */
243 for (i = 0; i < SHPS_NUM_IRQS; i++)
244 if (sdev->irq[i] != SHPS_IRQ_NOT_PRESENT)
245 shps_dsm_notify_irq(pdev, i);
246
247 return 0;
248
249 err:
250 surface_hotplug_remove(pdev);
251 return status;
252 }
253
254 static const struct acpi_device_id surface_hotplug_acpi_match[] = {
255 { "MSHW0153", 0 },
256 { },
257 };
258 MODULE_DEVICE_TABLE(acpi, surface_hotplug_acpi_match);
259
260 static struct platform_driver surface_hotplug_driver = {
261 .probe = surface_hotplug_probe,
262 .remove_new = surface_hotplug_remove,
263 .driver = {
264 .name = "surface_hotplug",
265 .acpi_match_table = surface_hotplug_acpi_match,
266 .probe_type = PROBE_PREFER_ASYNCHRONOUS,
267 },
268 };
269 module_platform_driver(surface_hotplug_driver);
270
271 MODULE_AUTHOR("Maximilian Luz <luzmaximilian@gmail.com>");
272 MODULE_DESCRIPTION("Surface Hot-Plug Signaling Driver for Surface Book Devices");
273 MODULE_LICENSE("GPL");
274