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 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 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 } 120 121 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 } 140 141 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 } 185 186 static int 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 return 0; 200 } 201 202 static int surface_hotplug_probe(struct platform_device *pdev) 203 { 204 struct shps_device *sdev; 205 int status, i; 206 207 /* 208 * The MSHW0153 device is also present on the Surface Laptop 3, 209 * however that doesn't have a hot-pluggable PCIe device. It also 210 * doesn't have any GPIO interrupts/pins under the MSHW0153, so filter 211 * it out here. 212 */ 213 if (gpiod_count(&pdev->dev, NULL) < 0) 214 return -ENODEV; 215 216 status = devm_acpi_dev_add_driver_gpios(&pdev->dev, shps_acpi_gpios); 217 if (status) 218 return status; 219 220 sdev = devm_kzalloc(&pdev->dev, sizeof(*sdev), GFP_KERNEL); 221 if (!sdev) 222 return -ENOMEM; 223 224 platform_set_drvdata(pdev, sdev); 225 226 /* 227 * Initialize IRQs so that we can safely call surface_hotplug_remove() 228 * on errors. 229 */ 230 for (i = 0; i < SHPS_NUM_IRQS; i++) 231 sdev->irq[i] = SHPS_IRQ_NOT_PRESENT; 232 233 /* Set up IRQs. */ 234 for (i = 0; i < SHPS_NUM_IRQS; i++) { 235 mutex_init(&sdev->lock[i]); 236 237 status = shps_setup_irq(pdev, i); 238 if (status) { 239 dev_err(&pdev->dev, "failed to set up IRQ %d: %d\n", i, status); 240 goto err; 241 } 242 } 243 244 /* Ensure everything is up-to-date. */ 245 for (i = 0; i < SHPS_NUM_IRQS; i++) 246 if (sdev->irq[i] != SHPS_IRQ_NOT_PRESENT) 247 shps_dsm_notify_irq(pdev, i); 248 249 return 0; 250 251 err: 252 surface_hotplug_remove(pdev); 253 return status; 254 } 255 256 static const struct acpi_device_id surface_hotplug_acpi_match[] = { 257 { "MSHW0153", 0 }, 258 { }, 259 }; 260 MODULE_DEVICE_TABLE(acpi, surface_hotplug_acpi_match); 261 262 static struct platform_driver surface_hotplug_driver = { 263 .probe = surface_hotplug_probe, 264 .remove = surface_hotplug_remove, 265 .driver = { 266 .name = "surface_hotplug", 267 .acpi_match_table = surface_hotplug_acpi_match, 268 .probe_type = PROBE_PREFER_ASYNCHRONOUS, 269 }, 270 }; 271 module_platform_driver(surface_hotplug_driver); 272 273 MODULE_AUTHOR("Maximilian Luz <luzmaximilian@gmail.com>"); 274 MODULE_DESCRIPTION("Surface Hot-Plug Signaling Driver for Surface Book Devices"); 275 MODULE_LICENSE("GPL"); 276