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  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_device.h>
 38#include <linux/slab.h>
 39#include <linux/suspend.h>
 40
 41#include <asm/cpu_device_id.h>
 42#include <asm/intel-family.h>
 43
 44#define DRV_NAME			"INT0002 Virtual GPIO"
 45
 46/* For some reason the virtual GPIO pin tied to the GPE is numbered pin 2 */
 47#define GPE0A_PME_B0_VIRT_GPIO_PIN	2
 48
 49#define GPE0A_PME_B0_STS_BIT		BIT(13)
 50#define GPE0A_PME_B0_EN_BIT		BIT(13)
 51#define GPE0A_STS_PORT			0x420
 52#define GPE0A_EN_PORT			0x428
 53
 54struct int0002_data {
 55	struct gpio_chip chip;
 56	int parent_irq;
 57	int wake_enable_count;
 58};
 59
 60/*
 61 * As this is not a real GPIO at all, but just a hack to model an event in
 62 * ACPI the get / set functions are dummy functions.
 63 */
 64
 65static int int0002_gpio_get(struct gpio_chip *chip, unsigned int offset)
 66{
 67	return 0;
 68}
 69
 70static void int0002_gpio_set(struct gpio_chip *chip, unsigned int offset,
 71			     int value)
 72{
 73}
 74
 75static int int0002_gpio_direction_output(struct gpio_chip *chip,
 76					 unsigned int offset, int value)
 77{
 78	return 0;
 79}
 80
 81static void int0002_irq_ack(struct irq_data *data)
 82{
 83	outl(GPE0A_PME_B0_STS_BIT, GPE0A_STS_PORT);
 84}
 85
 86static void int0002_irq_unmask(struct irq_data *data)
 87{
 88	u32 gpe_en_reg;
 89
 90	gpe_en_reg = inl(GPE0A_EN_PORT);
 91	gpe_en_reg |= GPE0A_PME_B0_EN_BIT;
 92	outl(gpe_en_reg, GPE0A_EN_PORT);
 93}
 94
 95static void int0002_irq_mask(struct irq_data *data)
 96{
 97	u32 gpe_en_reg;
 98
 99	gpe_en_reg = inl(GPE0A_EN_PORT);
100	gpe_en_reg &= ~GPE0A_PME_B0_EN_BIT;
101	outl(gpe_en_reg, GPE0A_EN_PORT);
102}
103
104static int int0002_irq_set_wake(struct irq_data *data, unsigned int on)
105{
106	struct gpio_chip *chip = irq_data_get_irq_chip_data(data);
107	struct int0002_data *int0002 = container_of(chip, struct int0002_data, chip);
108
109	/*
110	 * Applying of the wakeup flag to our parent IRQ is delayed till system
111	 * suspend, because we only want to do this when using s2idle.
112	 */
113	if (on)
114		int0002->wake_enable_count++;
115	else
116		int0002->wake_enable_count--;
117
118	return 0;
119}
120
121static irqreturn_t int0002_irq(int irq, void *data)
122{
123	struct gpio_chip *chip = data;
124	u32 gpe_sts_reg;
125
126	gpe_sts_reg = inl(GPE0A_STS_PORT);
127	if (!(gpe_sts_reg & GPE0A_PME_B0_STS_BIT))
128		return IRQ_NONE;
129
130	generic_handle_irq(irq_find_mapping(chip->irq.domain,
131					    GPE0A_PME_B0_VIRT_GPIO_PIN));
132
133	pm_wakeup_hard_event(chip->parent);
134
135	return IRQ_HANDLED;
136}
137
138static bool int0002_check_wake(void *data)
139{
140	u32 gpe_sts_reg;
141
142	gpe_sts_reg = inl(GPE0A_STS_PORT);
143	return (gpe_sts_reg & GPE0A_PME_B0_STS_BIT);
144}
145
146static struct irq_chip int0002_irqchip = {
147	.name			= DRV_NAME,
148	.irq_ack		= int0002_irq_ack,
149	.irq_mask		= int0002_irq_mask,
150	.irq_unmask		= int0002_irq_unmask,
151	.irq_set_wake		= int0002_irq_set_wake,
152};
153
154static const struct x86_cpu_id int0002_cpu_ids[] = {
155	X86_MATCH_INTEL_FAM6_MODEL(ATOM_SILVERMONT, NULL),
156	X86_MATCH_INTEL_FAM6_MODEL(ATOM_AIRMONT, NULL),
157	{}
158};
159
160static void int0002_init_irq_valid_mask(struct gpio_chip *chip,
161					unsigned long *valid_mask,
162					unsigned int ngpios)
163{
164	bitmap_clear(valid_mask, 0, GPE0A_PME_B0_VIRT_GPIO_PIN);
165}
166
167static int int0002_probe(struct platform_device *pdev)
168{
169	struct device *dev = &pdev->dev;
170	const struct x86_cpu_id *cpu_id;
171	struct int0002_data *int0002;
172	struct gpio_irq_chip *girq;
173	struct gpio_chip *chip;
174	int irq, ret;
175
176	/* Menlow has a different INT0002 device? <sigh> */
177	cpu_id = x86_match_cpu(int0002_cpu_ids);
178	if (!cpu_id)
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,
210			       IRQF_SHARED, "INT0002", 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	girq->chip = &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 int int0002_remove(struct platform_device *pdev)
238{
239	device_init_wakeup(&pdev->dev, false);
240	acpi_unregister_wakeup_handler(int0002_check_wake, NULL);
241	return 0;
242}
243
244static int int0002_suspend(struct device *dev)
245{
246	struct int0002_data *int0002 = dev_get_drvdata(dev);
247
248	/*
249	 * The INT0002 parent IRQ is often shared with the ACPI GPE IRQ, don't
250	 * muck with it when firmware based suspend is used, otherwise we may
251	 * cause spurious wakeups from firmware managed suspend.
252	 */
253	if (!pm_suspend_via_firmware() && int0002->wake_enable_count)
254		enable_irq_wake(int0002->parent_irq);
255
256	return 0;
257}
258
259static int int0002_resume(struct device *dev)
260{
261	struct int0002_data *int0002 = dev_get_drvdata(dev);
262
263	if (!pm_suspend_via_firmware() && int0002->wake_enable_count)
264		disable_irq_wake(int0002->parent_irq);
265
266	return 0;
267}
268
269static const struct dev_pm_ops int0002_pm_ops = {
270	.suspend = int0002_suspend,
271	.resume = int0002_resume,
272};
273
274static const struct acpi_device_id int0002_acpi_ids[] = {
275	{ "INT0002", 0 },
276	{ },
277};
278MODULE_DEVICE_TABLE(acpi, int0002_acpi_ids);
279
280static struct platform_driver int0002_driver = {
281	.driver = {
282		.name			= DRV_NAME,
283		.acpi_match_table	= int0002_acpi_ids,
284		.pm			= &int0002_pm_ops,
285	},
286	.probe	= int0002_probe,
287	.remove	= int0002_remove,
288};
289
290module_platform_driver(int0002_driver);
291
292MODULE_AUTHOR("Hans de Goede <hdegoede@redhat.com>");
293MODULE_DESCRIPTION("Intel INT0002 Virtual GPIO driver");
294MODULE_LICENSE("GPL v2");