1/*
  2 * Intel INT0002 "Virtual GPIO" driver
  3 *
  4 * Copyright (C) 2017 Hans de Goede <hdegoede@redhat.com>
  5 *
  6 * Loosely based on android x86 kernel code which is:
  7 *
  8 * Copyright (c) 2014, Intel Corporation.
  9 *
 10 * Author: Dyut Kumar Sil <dyut.k.sil@intel.com>
 11 *
 12 * This program is free software; you can redistribute it and/or modify
 13 * it under the terms of the GNU General Public License version 2 as
 14 * published by the Free Software Foundation.
 15 *
 16 * Some peripherals on Bay Trail and Cherry Trail platforms signal a Power
 17 * Management Event (PME) to the Power Management Controller (PMC) to wakeup
 18 * the system. When this happens software needs to clear the PME bus 0 status
 19 * bit in the GPE0a_STS register to avoid an IRQ storm on IRQ 9.
 20 *
 21 * This is modelled in ACPI through the INT0002 ACPI device, which is
 22 * called a "Virtual GPIO controller" in ACPI because it defines the event
 23 * handler to call when the PME triggers through _AEI and _L02 / _E02
 24 * methods as would be done for a real GPIO interrupt in ACPI. Note this
 25 * is a hack to define an AML event handler for the PME while using existing
 26 * ACPI mechanisms, this is not a real GPIO at all.
 27 *
 28 * This driver will bind to the INT0002 device, and register as a GPIO
 29 * controller, letting gpiolib-acpi.c call the _L02 handler as it would
 30 * for a real GPIO controller.
 31 */
 32
 33#include <linux/acpi.h>
 34#include <linux/bitmap.h>
 35#include <linux/gpio/driver.h>
 36#include <linux/interrupt.h>
 37#include <linux/io.h>
 38#include <linux/kernel.h>
 39#include <linux/module.h>
 40#include <linux/platform_device.h>
 41#include <linux/slab.h>
 42#include <linux/suspend.h>
 43
 44#include <asm/cpu_device_id.h>
 45#include <asm/intel-family.h>
 46
 47#define DRV_NAME			"INT0002 Virtual GPIO"
 48
 49/* For some reason the virtual GPIO pin tied to the GPE is numbered pin 2 */
 50#define GPE0A_PME_B0_VIRT_GPIO_PIN	2
 51
 52#define GPE0A_PME_B0_STS_BIT		BIT(13)
 53#define GPE0A_PME_B0_EN_BIT		BIT(13)
 54#define GPE0A_STS_PORT			0x420
 55#define GPE0A_EN_PORT			0x428
 56
 57#define ICPU(model)	{ X86_VENDOR_INTEL, 6, model, X86_FEATURE_ANY, }
 58
 59static const struct x86_cpu_id int0002_cpu_ids[] = {
 60/*
 61 * Limit ourselves to Cherry Trail for now, until testing shows we
 62 * need to handle the INT0002 device on Baytrail too.
 63 *	ICPU(INTEL_FAM6_ATOM_SILVERMONT1),	 * Valleyview, Bay Trail *
 64 */
 65	ICPU(INTEL_FAM6_ATOM_AIRMONT),		/* Braswell, Cherry Trail */
 66	{}
 67};
 68
 69/*
 70 * As this is not a real GPIO at all, but just a hack to model an event in
 71 * ACPI the get / set functions are dummy functions.
 72 */
 73
 74static int int0002_gpio_get(struct gpio_chip *chip, unsigned int offset)
 75{
 76	return 0;
 77}
 78
 79static void int0002_gpio_set(struct gpio_chip *chip, unsigned int offset,
 80			     int value)
 81{
 82}
 83
 84static int int0002_gpio_direction_output(struct gpio_chip *chip,
 85					 unsigned int offset, int value)
 86{
 87	return 0;
 88}
 89
 90static void int0002_irq_ack(struct irq_data *data)
 91{
 92	outl(GPE0A_PME_B0_STS_BIT, GPE0A_STS_PORT);
 93}
 94
 95static void int0002_irq_unmask(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 void int0002_irq_mask(struct irq_data *data)
105{
106	u32 gpe_en_reg;
107
108	gpe_en_reg = inl(GPE0A_EN_PORT);
109	gpe_en_reg &= ~GPE0A_PME_B0_EN_BIT;
110	outl(gpe_en_reg, GPE0A_EN_PORT);
111}
112
113static irqreturn_t int0002_irq(int irq, void *data)
114{
115	struct gpio_chip *chip = data;
116	u32 gpe_sts_reg;
117
118	gpe_sts_reg = inl(GPE0A_STS_PORT);
119	if (!(gpe_sts_reg & GPE0A_PME_B0_STS_BIT))
120		return IRQ_NONE;
121
122	generic_handle_irq(irq_find_mapping(chip->irq.domain,
123					    GPE0A_PME_B0_VIRT_GPIO_PIN));
124
125	pm_system_wakeup();
126
127	return IRQ_HANDLED;
128}
129
130static struct irq_chip int0002_irqchip = {
131	.name			= DRV_NAME,
132	.irq_ack		= int0002_irq_ack,
133	.irq_mask		= int0002_irq_mask,
134	.irq_unmask		= int0002_irq_unmask,
135};
136
137static int int0002_probe(struct platform_device *pdev)
138{
139	struct device *dev = &pdev->dev;
140	const struct x86_cpu_id *cpu_id;
141	struct gpio_chip *chip;
142	int irq, ret;
143
144	/* Menlow has a different INT0002 device? <sigh> */
145	cpu_id = x86_match_cpu(int0002_cpu_ids);
146	if (!cpu_id)
147		return -ENODEV;
148
149	irq = platform_get_irq(pdev, 0);
150	if (irq < 0) {
151		dev_err(dev, "Error getting IRQ: %d\n", irq);
152		return irq;
153	}
154
155	chip = devm_kzalloc(dev, sizeof(*chip), GFP_KERNEL);
156	if (!chip)
157		return -ENOMEM;
158
159	chip->label = DRV_NAME;
160	chip->parent = dev;
161	chip->owner = THIS_MODULE;
162	chip->get = int0002_gpio_get;
163	chip->set = int0002_gpio_set;
164	chip->direction_input = int0002_gpio_get;
165	chip->direction_output = int0002_gpio_direction_output;
166	chip->base = -1;
167	chip->ngpio = GPE0A_PME_B0_VIRT_GPIO_PIN + 1;
168	chip->irq.need_valid_mask = true;
169
170	ret = devm_gpiochip_add_data(&pdev->dev, chip, NULL);
171	if (ret) {
172		dev_err(dev, "Error adding gpio chip: %d\n", ret);
173		return ret;
174	}
175
176	bitmap_clear(chip->irq.valid_mask, 0, GPE0A_PME_B0_VIRT_GPIO_PIN);
177
178	/*
179	 * We manually request the irq here instead of passing a flow-handler
180	 * to gpiochip_set_chained_irqchip, because the irq is shared.
181	 */
182	ret = devm_request_irq(dev, irq, int0002_irq,
183			       IRQF_SHARED, "INT0002", chip);
184	if (ret) {
185		dev_err(dev, "Error requesting IRQ %d: %d\n", irq, ret);
186		return ret;
187	}
188
189	ret = gpiochip_irqchip_add(chip, &int0002_irqchip, 0, handle_edge_irq,
190				   IRQ_TYPE_NONE);
191	if (ret) {
192		dev_err(dev, "Error adding irqchip: %d\n", ret);
193		return ret;
194	}
195
196	gpiochip_set_chained_irqchip(chip, &int0002_irqchip, irq, NULL);
197
198	return 0;
199}
200
201static const struct acpi_device_id int0002_acpi_ids[] = {
202	{ "INT0002", 0 },
203	{ },
204};
205MODULE_DEVICE_TABLE(acpi, int0002_acpi_ids);
206
207static struct platform_driver int0002_driver = {
208	.driver = {
209		.name			= DRV_NAME,
210		.acpi_match_table	= int0002_acpi_ids,
211	},
212	.probe	= int0002_probe,
213};
214
215module_platform_driver(int0002_driver);
216
217MODULE_AUTHOR("Hans de Goede <hdegoede@redhat.com>");
218MODULE_DESCRIPTION("Intel INT0002 Virtual GPIO driver");
219MODULE_LICENSE("GPL");