int0002_vgpio.c

  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 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 int int0002_gpio_set(struct gpio_chip *chip, unsigned int offset,
 69			    int value)
 70{
 71	return 0;
 72}
 73
 74static int int0002_gpio_direction_output(struct gpio_chip *chip,
 75					 unsigned int offset, int value)
 76{
 77	return 0;
 78}
 79
 80static void int0002_irq_ack(struct irq_data *data)
 81{
 82	outl(GPE0A_PME_B0_STS_BIT, GPE0A_STS_PORT);
 83}
 84
 85static void int0002_irq_unmask(struct irq_data *data)
 86{
 87	struct gpio_chip *gc = irq_data_get_irq_chip_data(data);
 88	irq_hw_number_t hwirq = irqd_to_hwirq(data);
 89	u32 gpe_en_reg;
 90
 91	gpiochip_enable_irq(gc, hwirq);
 92
 93	gpe_en_reg = inl(GPE0A_EN_PORT);
 94	gpe_en_reg |= GPE0A_PME_B0_EN_BIT;
 95	outl(gpe_en_reg, GPE0A_EN_PORT);
 96}
 97
 98static void int0002_irq_mask(struct irq_data *data)
 99{
100	struct gpio_chip *gc = irq_data_get_irq_chip_data(data);
101	irq_hw_number_t hwirq = irqd_to_hwirq(data);
102	u32 gpe_en_reg;
103
104	gpe_en_reg = inl(GPE0A_EN_PORT);
105	gpe_en_reg &= ~GPE0A_PME_B0_EN_BIT;
106	outl(gpe_en_reg, GPE0A_EN_PORT);
107
108	gpiochip_disable_irq(gc, hwirq);
109}
110
111static int int0002_irq_set_wake(struct irq_data *data, unsigned int on)
112{
113	struct gpio_chip *chip = irq_data_get_irq_chip_data(data);
114	struct int0002_data *int0002 = container_of(chip, struct int0002_data, chip);
115
116	/*
117	 * Applying of the wakeup flag to our parent IRQ is delayed till system
118	 * suspend, because we only want to do this when using s2idle.
119	 */
120	if (on)
121		int0002->wake_enable_count++;
122	else
123		int0002->wake_enable_count--;
124
125	return 0;
126}
127
128static irqreturn_t int0002_irq(int irq, void *data)
129{
130	struct gpio_chip *chip = data;
131	u32 gpe_sts_reg;
132
133	gpe_sts_reg = inl(GPE0A_STS_PORT);
134	if (!(gpe_sts_reg & GPE0A_PME_B0_STS_BIT))
135		return IRQ_NONE;
136
137	generic_handle_domain_irq_safe(chip->irq.domain, GPE0A_PME_B0_VIRT_GPIO_PIN);
138
139	pm_wakeup_hard_event(chip->parent);
140
141	return IRQ_HANDLED;
142}
143
144static bool int0002_check_wake(void *data)
145{
146	u32 gpe_sts_reg;
147
148	gpe_sts_reg = inl(GPE0A_STS_PORT);
149	return (gpe_sts_reg & GPE0A_PME_B0_STS_BIT);
150}
151
152static const struct irq_chip int0002_irqchip = {
153	.name			= DRV_NAME,
154	.irq_ack		= int0002_irq_ack,
155	.irq_mask		= int0002_irq_mask,
156	.irq_unmask		= int0002_irq_unmask,
157	.irq_set_wake		= int0002_irq_set_wake,
158	.flags			= IRQCHIP_IMMUTABLE,
159	GPIOCHIP_IRQ_RESOURCE_HELPERS,
160};
161
162static void int0002_init_irq_valid_mask(struct gpio_chip *chip,
163					unsigned long *valid_mask,
164					unsigned int ngpios)
165{
166	bitmap_clear(valid_mask, 0, GPE0A_PME_B0_VIRT_GPIO_PIN);
167}
168
169static int int0002_probe(struct platform_device *pdev)
170{
171	struct device *dev = &pdev->dev;
172	struct int0002_data *int0002;
173	struct gpio_irq_chip *girq;
174	struct gpio_chip *chip;
175	int irq, ret;
176
177	/* Menlow has a different INT0002 device? <sigh> */
178	if (!soc_intel_is_byt() && !soc_intel_is_cht())
179		return -ENODEV;
180
181	irq = platform_get_irq(pdev, 0);
182	if (irq < 0)
183		return irq;
184
185	int0002 = devm_kzalloc(dev, sizeof(*int0002), GFP_KERNEL);
186	if (!int0002)
187		return -ENOMEM;
188
189	int0002->parent_irq = irq;
190
191	chip = &int0002->chip;
192	chip->label = DRV_NAME;
193	chip->parent = dev;
194	chip->owner = THIS_MODULE;
195	chip->get = int0002_gpio_get;
196	chip->set = int0002_gpio_set;
197	chip->direction_input = int0002_gpio_get;
198	chip->direction_output = int0002_gpio_direction_output;
199	chip->base = -1;
200	chip->ngpio = GPE0A_PME_B0_VIRT_GPIO_PIN + 1;
201	chip->irq.init_valid_mask = int0002_init_irq_valid_mask;
202
203	/*
204	 * We directly request the irq here instead of passing a flow-handler
205	 * to gpiochip_set_chained_irqchip, because the irq is shared.
206	 * FIXME: augment this if we managed to pull handling of shared
207	 * IRQs into gpiolib.
208	 */
209	ret = devm_request_irq(dev, irq, int0002_irq, IRQF_SHARED, "INT0002",
210			       chip);
211	if (ret) {
212		dev_err(dev, "Error requesting IRQ %d: %d\n", irq, ret);
213		return ret;
214	}
215
216	girq = &chip->irq;
217	gpio_irq_chip_set_chip(girq, &int0002_irqchip);
218	/* This let us handle the parent IRQ in the driver */
219	girq->parent_handler = NULL;
220	girq->num_parents = 0;
221	girq->parents = NULL;
222	girq->default_type = IRQ_TYPE_NONE;
223	girq->handler = handle_edge_irq;
224
225	ret = devm_gpiochip_add_data(dev, chip, NULL);
226	if (ret) {
227		dev_err(dev, "Error adding gpio chip: %d\n", ret);
228		return ret;
229	}
230
231	acpi_register_wakeup_handler(irq, int0002_check_wake, NULL);
232	device_init_wakeup(dev, true);
233	dev_set_drvdata(dev, int0002);
234	return 0;
235}
236
237static void int0002_remove(struct platform_device *pdev)
238{
239	device_init_wakeup(&pdev->dev, false);
240	acpi_unregister_wakeup_handler(int0002_check_wake, NULL);
241}
242
243static int int0002_suspend(struct device *dev)
244{
245	struct int0002_data *int0002 = dev_get_drvdata(dev);
246
247	/*
248	 * The INT0002 parent IRQ is often shared with the ACPI GPE IRQ, don't
249	 * muck with it when firmware based suspend is used, otherwise we may
250	 * cause spurious wakeups from firmware managed suspend.
251	 */
252	if (!pm_suspend_via_firmware() && int0002->wake_enable_count)
253		enable_irq_wake(int0002->parent_irq);
254
255	return 0;
256}
257
258static int int0002_resume(struct device *dev)
259{
260	struct int0002_data *int0002 = dev_get_drvdata(dev);
261
262	if (!pm_suspend_via_firmware() && int0002->wake_enable_count)
263		disable_irq_wake(int0002->parent_irq);
264
265	return 0;
266}
267
268static const struct dev_pm_ops int0002_pm_ops = {
269	.suspend = int0002_suspend,
270	.resume = int0002_resume,
271};
272
273static const struct acpi_device_id int0002_acpi_ids[] = {
274	{ "INT0002", 0 },
275	{ },
276};
277MODULE_DEVICE_TABLE(acpi, int0002_acpi_ids);
278
279static struct platform_driver int0002_driver = {
280	.driver	= {
281		.name			= DRV_NAME,
282		.acpi_match_table	= int0002_acpi_ids,
283		.pm			= &int0002_pm_ops,
284	},
285	.probe	= int0002_probe,
286	.remove	= int0002_remove,
287};
288
289module_platform_driver(int0002_driver);
290
291MODULE_AUTHOR("Hans de Goede <hdegoede@redhat.com>");
292MODULE_DESCRIPTION("Intel INT0002 Virtual GPIO driver");
293MODULE_LICENSE("GPL v2");