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
 52struct 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
 63static int int0002_gpio_get(struct gpio_chip *chip, unsigned int offset)
 64{
 65	return 0;
 66}
 67
 68static void int0002_gpio_set(struct gpio_chip *chip, unsigned int offset,
 69			     int value)
 70{
 71}
 72
 73static int int0002_gpio_direction_output(struct gpio_chip *chip,
 74					 unsigned int offset, int value)
 75{
 76	return 0;
 77}
 78
 79static void int0002_irq_ack(struct irq_data *data)
 80{
 81	outl(GPE0A_PME_B0_STS_BIT, GPE0A_STS_PORT);
 82}
 83
 84static 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
 93static 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
102static 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
119static 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
135static 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
143static 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
151static 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
158static 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
226static 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
233static 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
248static 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
258static const struct dev_pm_ops int0002_pm_ops = {
259	.suspend = int0002_suspend,
260	.resume = int0002_resume,
261};
262
263static const struct acpi_device_id int0002_acpi_ids[] = {
264	{ "INT0002", 0 },
265	{ },
266};
267MODULE_DEVICE_TABLE(acpi, int0002_acpi_ids);
268
269static 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
279module_platform_driver(int0002_driver);
280
281MODULE_AUTHOR("Hans de Goede <hdegoede@redhat.com>");
282MODULE_DESCRIPTION("Intel INT0002 Virtual GPIO driver");
283MODULE_LICENSE("GPL v2");