1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Intel INT0002 "Virtual GPIO" driver
4  *
5  * Copyright (C) 2017 Hans de Goede <hdegoede@redhat.com>
6  *
7  * Loosely based on android x86 kernel code which is:
8  *
9  * Copyright (c) 2014, Intel Corporation.
10  *
11  * Author: Dyut Kumar Sil <dyut.k.sil@intel.com>
12  *
13  * Some peripherals on Bay Trail and Cherry Trail platforms signal a Power
14  * Management Event (PME) to the Power Management Controller (PMC) to wakeup
15  * the system. When this happens software needs to clear the PME bus 0 status
16  * bit in the GPE0a_STS register to avoid an IRQ storm on IRQ 9.
17  *
18  * This is modelled in ACPI through the INT0002 ACPI device, which is
19  * called a "Virtual GPIO controller" in ACPI because it defines the event
20  * handler to call when the PME triggers through _AEI and _L02 / _E02
21  * methods as would be done for a real GPIO interrupt in ACPI. Note this
22  * is a hack to define an AML event handler for the PME while using existing
23  * ACPI mechanisms, this is not a real GPIO at all.
24  *
25  * This driver will bind to the INT0002 device, and register as a GPIO
26  * controller, letting gpiolib-acpi.c call the _L02 handler as it would
27  * for a real GPIO controller.
28  */
29 
30 #include <linux/acpi.h>
31 #include <linux/bitmap.h>
32 #include <linux/gpio/driver.h>
33 #include <linux/interrupt.h>
34 #include <linux/io.h>
35 #include <linux/kernel.h>
36 #include <linux/module.h>
37 #include <linux/platform_data/x86/soc.h>
38 #include <linux/platform_device.h>
39 #include <linux/slab.h>
40 #include <linux/suspend.h>
41 
42 #define DRV_NAME			"INT0002 Virtual GPIO"
43 
44 /* For some reason the virtual GPIO pin tied to the GPE is numbered pin 2 */
45 #define GPE0A_PME_B0_VIRT_GPIO_PIN	2
46 
47 #define GPE0A_PME_B0_STS_BIT		BIT(13)
48 #define GPE0A_PME_B0_EN_BIT		BIT(13)
49 #define GPE0A_STS_PORT			0x420
50 #define GPE0A_EN_PORT			0x428
51 
52 struct int0002_data {
53 	struct gpio_chip chip;
54 	int parent_irq;
55 	int wake_enable_count;
56 };
57 
58 /*
59  * As this is not a real GPIO at all, but just a hack to model an event in
60  * ACPI the get / set functions are dummy functions.
61  */
62 
63 static int int0002_gpio_get(struct gpio_chip *chip, unsigned int offset)
64 {
65 	return 0;
66 }
67 
68 static void int0002_gpio_set(struct gpio_chip *chip, unsigned int offset,
69 			     int value)
70 {
71 }
72 
73 static int int0002_gpio_direction_output(struct gpio_chip *chip,
74 					 unsigned int offset, int value)
75 {
76 	return 0;
77 }
78 
79 static void int0002_irq_ack(struct irq_data *data)
80 {
81 	outl(GPE0A_PME_B0_STS_BIT, GPE0A_STS_PORT);
82 }
83 
84 static void int0002_irq_unmask(struct irq_data *data)
85 {
86 	u32 gpe_en_reg;
87 
88 	gpe_en_reg = inl(GPE0A_EN_PORT);
89 	gpe_en_reg |= GPE0A_PME_B0_EN_BIT;
90 	outl(gpe_en_reg, GPE0A_EN_PORT);
91 }
92 
93 static void int0002_irq_mask(struct irq_data *data)
94 {
95 	u32 gpe_en_reg;
96 
97 	gpe_en_reg = inl(GPE0A_EN_PORT);
98 	gpe_en_reg &= ~GPE0A_PME_B0_EN_BIT;
99 	outl(gpe_en_reg, GPE0A_EN_PORT);
100 }
101 
102 static int int0002_irq_set_wake(struct irq_data *data, unsigned int on)
103 {
104 	struct gpio_chip *chip = irq_data_get_irq_chip_data(data);
105 	struct int0002_data *int0002 = container_of(chip, struct int0002_data, chip);
106 
107 	/*
108 	 * Applying of the wakeup flag to our parent IRQ is delayed till system
109 	 * suspend, because we only want to do this when using s2idle.
110 	 */
111 	if (on)
112 		int0002->wake_enable_count++;
113 	else
114 		int0002->wake_enable_count--;
115 
116 	return 0;
117 }
118 
119 static irqreturn_t int0002_irq(int irq, void *data)
120 {
121 	struct gpio_chip *chip = data;
122 	u32 gpe_sts_reg;
123 
124 	gpe_sts_reg = inl(GPE0A_STS_PORT);
125 	if (!(gpe_sts_reg & GPE0A_PME_B0_STS_BIT))
126 		return IRQ_NONE;
127 
128 	generic_handle_domain_irq_safe(chip->irq.domain, GPE0A_PME_B0_VIRT_GPIO_PIN);
129 
130 	pm_wakeup_hard_event(chip->parent);
131 
132 	return IRQ_HANDLED;
133 }
134 
135 static bool int0002_check_wake(void *data)
136 {
137 	u32 gpe_sts_reg;
138 
139 	gpe_sts_reg = inl(GPE0A_STS_PORT);
140 	return (gpe_sts_reg & GPE0A_PME_B0_STS_BIT);
141 }
142 
143 static struct irq_chip int0002_irqchip = {
144 	.name			= DRV_NAME,
145 	.irq_ack		= int0002_irq_ack,
146 	.irq_mask		= int0002_irq_mask,
147 	.irq_unmask		= int0002_irq_unmask,
148 	.irq_set_wake		= int0002_irq_set_wake,
149 };
150 
151 static void int0002_init_irq_valid_mask(struct gpio_chip *chip,
152 					unsigned long *valid_mask,
153 					unsigned int ngpios)
154 {
155 	bitmap_clear(valid_mask, 0, GPE0A_PME_B0_VIRT_GPIO_PIN);
156 }
157 
158 static int int0002_probe(struct platform_device *pdev)
159 {
160 	struct device *dev = &pdev->dev;
161 	struct int0002_data *int0002;
162 	struct gpio_irq_chip *girq;
163 	struct gpio_chip *chip;
164 	int irq, ret;
165 
166 	/* Menlow has a different INT0002 device? <sigh> */
167 	if (!soc_intel_is_byt() && !soc_intel_is_cht())
168 		return -ENODEV;
169 
170 	irq = platform_get_irq(pdev, 0);
171 	if (irq < 0)
172 		return irq;
173 
174 	int0002 = devm_kzalloc(dev, sizeof(*int0002), GFP_KERNEL);
175 	if (!int0002)
176 		return -ENOMEM;
177 
178 	int0002->parent_irq = irq;
179 
180 	chip = &int0002->chip;
181 	chip->label = DRV_NAME;
182 	chip->parent = dev;
183 	chip->owner = THIS_MODULE;
184 	chip->get = int0002_gpio_get;
185 	chip->set = int0002_gpio_set;
186 	chip->direction_input = int0002_gpio_get;
187 	chip->direction_output = int0002_gpio_direction_output;
188 	chip->base = -1;
189 	chip->ngpio = GPE0A_PME_B0_VIRT_GPIO_PIN + 1;
190 	chip->irq.init_valid_mask = int0002_init_irq_valid_mask;
191 
192 	/*
193 	 * We directly request the irq here instead of passing a flow-handler
194 	 * to gpiochip_set_chained_irqchip, because the irq is shared.
195 	 * FIXME: augment this if we managed to pull handling of shared
196 	 * IRQs into gpiolib.
197 	 */
198 	ret = devm_request_irq(dev, irq, int0002_irq,
199 			       IRQF_SHARED, "INT0002", chip);
200 	if (ret) {
201 		dev_err(dev, "Error requesting IRQ %d: %d\n", irq, ret);
202 		return ret;
203 	}
204 
205 	girq = &chip->irq;
206 	girq->chip = &int0002_irqchip;
207 	/* This let us handle the parent IRQ in the driver */
208 	girq->parent_handler = NULL;
209 	girq->num_parents = 0;
210 	girq->parents = NULL;
211 	girq->default_type = IRQ_TYPE_NONE;
212 	girq->handler = handle_edge_irq;
213 
214 	ret = devm_gpiochip_add_data(dev, chip, NULL);
215 	if (ret) {
216 		dev_err(dev, "Error adding gpio chip: %d\n", ret);
217 		return ret;
218 	}
219 
220 	acpi_register_wakeup_handler(irq, int0002_check_wake, NULL);
221 	device_init_wakeup(dev, true);
222 	dev_set_drvdata(dev, int0002);
223 	return 0;
224 }
225 
226 static int int0002_remove(struct platform_device *pdev)
227 {
228 	device_init_wakeup(&pdev->dev, false);
229 	acpi_unregister_wakeup_handler(int0002_check_wake, NULL);
230 	return 0;
231 }
232 
233 static int int0002_suspend(struct device *dev)
234 {
235 	struct int0002_data *int0002 = dev_get_drvdata(dev);
236 
237 	/*
238 	 * The INT0002 parent IRQ is often shared with the ACPI GPE IRQ, don't
239 	 * muck with it when firmware based suspend is used, otherwise we may
240 	 * cause spurious wakeups from firmware managed suspend.
241 	 */
242 	if (!pm_suspend_via_firmware() && int0002->wake_enable_count)
243 		enable_irq_wake(int0002->parent_irq);
244 
245 	return 0;
246 }
247 
248 static int int0002_resume(struct device *dev)
249 {
250 	struct int0002_data *int0002 = dev_get_drvdata(dev);
251 
252 	if (!pm_suspend_via_firmware() && int0002->wake_enable_count)
253 		disable_irq_wake(int0002->parent_irq);
254 
255 	return 0;
256 }
257 
258 static const struct dev_pm_ops int0002_pm_ops = {
259 	.suspend = int0002_suspend,
260 	.resume = int0002_resume,
261 };
262 
263 static const struct acpi_device_id int0002_acpi_ids[] = {
264 	{ "INT0002", 0 },
265 	{ },
266 };
267 MODULE_DEVICE_TABLE(acpi, int0002_acpi_ids);
268 
269 static struct platform_driver int0002_driver = {
270 	.driver = {
271 		.name			= DRV_NAME,
272 		.acpi_match_table	= int0002_acpi_ids,
273 		.pm			= &int0002_pm_ops,
274 	},
275 	.probe	= int0002_probe,
276 	.remove	= int0002_remove,
277 };
278 
279 module_platform_driver(int0002_driver);
280 
281 MODULE_AUTHOR("Hans de Goede <hdegoede@redhat.com>");
282 MODULE_DESCRIPTION("Intel INT0002 Virtual GPIO driver");
283 MODULE_LICENSE("GPL v2");
284