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/*
* Intel INT0002 "Virtual GPIO" driver
*
* Copyright (C) 2017 Hans de Goede <hdegoede@redhat.com>
*
* Loosely based on android x86 kernel code which is:
*
* Copyright (c) 2014, Intel Corporation.
*
* Author: Dyut Kumar Sil <dyut.k.sil@intel.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* Some peripherals on Bay Trail and Cherry Trail platforms signal a Power
* Management Event (PME) to the Power Management Controller (PMC) to wakeup
* the system. When this happens software needs to clear the PME bus 0 status
* bit in the GPE0a_STS register to avoid an IRQ storm on IRQ 9.
*
* This is modelled in ACPI through the INT0002 ACPI device, which is
* called a "Virtual GPIO controller" in ACPI because it defines the event
* handler to call when the PME triggers through _AEI and _L02 / _E02
* methods as would be done for a real GPIO interrupt in ACPI. Note this
* is a hack to define an AML event handler for the PME while using existing
* ACPI mechanisms, this is not a real GPIO at all.
*
* This driver will bind to the INT0002 device, and register as a GPIO
* controller, letting gpiolib-acpi.c call the _L02 handler as it would
* for a real GPIO controller.
*/
#include <linux/acpi.h>
#include <linux/bitmap.h>
#include <linux/gpio/driver.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/suspend.h>
#include <asm/cpu_device_id.h>
#include <asm/intel-family.h>
#define DRV_NAME "INT0002 Virtual GPIO"
/* For some reason the virtual GPIO pin tied to the GPE is numbered pin 2 */
#define GPE0A_PME_B0_VIRT_GPIO_PIN 2
#define GPE0A_PME_B0_STS_BIT BIT(13)
#define GPE0A_PME_B0_EN_BIT BIT(13)
#define GPE0A_STS_PORT 0x420
#define GPE0A_EN_PORT 0x428
#define ICPU(model) { X86_VENDOR_INTEL, 6, model, X86_FEATURE_ANY, }
static const struct x86_cpu_id int0002_cpu_ids[] = {
/*
* Limit ourselves to Cherry Trail for now, until testing shows we
* need to handle the INT0002 device on Baytrail too.
* ICPU(INTEL_FAM6_ATOM_SILVERMONT), * Valleyview, Bay Trail *
*/
ICPU(INTEL_FAM6_ATOM_AIRMONT), /* Braswell, Cherry Trail */
{}
};
/*
* As this is not a real GPIO at all, but just a hack to model an event in
* ACPI the get / set functions are dummy functions.
*/
static int int0002_gpio_get(struct gpio_chip *chip, unsigned int offset)
{
return 0;
}
static void int0002_gpio_set(struct gpio_chip *chip, unsigned int offset,
int value)
{
}
static int int0002_gpio_direction_output(struct gpio_chip *chip,
unsigned int offset, int value)
{
return 0;
}
static void int0002_irq_ack(struct irq_data *data)
{
outl(GPE0A_PME_B0_STS_BIT, GPE0A_STS_PORT);
}
static void int0002_irq_unmask(struct irq_data *data)
{
u32 gpe_en_reg;
gpe_en_reg = inl(GPE0A_EN_PORT);
gpe_en_reg |= GPE0A_PME_B0_EN_BIT;
outl(gpe_en_reg, GPE0A_EN_PORT);
}
static void int0002_irq_mask(struct irq_data *data)
{
u32 gpe_en_reg;
gpe_en_reg = inl(GPE0A_EN_PORT);
gpe_en_reg &= ~GPE0A_PME_B0_EN_BIT;
outl(gpe_en_reg, GPE0A_EN_PORT);
}
static irqreturn_t int0002_irq(int irq, void *data)
{
struct gpio_chip *chip = data;
u32 gpe_sts_reg;
gpe_sts_reg = inl(GPE0A_STS_PORT);
if (!(gpe_sts_reg & GPE0A_PME_B0_STS_BIT))
return IRQ_NONE;
generic_handle_irq(irq_find_mapping(chip->irq.domain,
GPE0A_PME_B0_VIRT_GPIO_PIN));
pm_system_wakeup();
return IRQ_HANDLED;
}
static struct irq_chip int0002_irqchip = {
.name = DRV_NAME,
.irq_ack = int0002_irq_ack,
.irq_mask = int0002_irq_mask,
.irq_unmask = int0002_irq_unmask,
};
static int int0002_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
const struct x86_cpu_id *cpu_id;
struct gpio_chip *chip;
int irq, ret;
/* Menlow has a different INT0002 device? <sigh> */
cpu_id = x86_match_cpu(int0002_cpu_ids);
if (!cpu_id)
return -ENODEV;
irq = platform_get_irq(pdev, 0);
if (irq < 0) {
dev_err(dev, "Error getting IRQ: %d\n", irq);
return irq;
}
chip = devm_kzalloc(dev, sizeof(*chip), GFP_KERNEL);
if (!chip)
return -ENOMEM;
chip->label = DRV_NAME;
chip->parent = dev;
chip->owner = THIS_MODULE;
chip->get = int0002_gpio_get;
chip->set = int0002_gpio_set;
chip->direction_input = int0002_gpio_get;
chip->direction_output = int0002_gpio_direction_output;
chip->base = -1;
chip->ngpio = GPE0A_PME_B0_VIRT_GPIO_PIN + 1;
chip->irq.need_valid_mask = true;
ret = devm_gpiochip_add_data(&pdev->dev, chip, NULL);
if (ret) {
dev_err(dev, "Error adding gpio chip: %d\n", ret);
return ret;
}
bitmap_clear(chip->irq.valid_mask, 0, GPE0A_PME_B0_VIRT_GPIO_PIN);
/*
* We manually request the irq here instead of passing a flow-handler
* to gpiochip_set_chained_irqchip, because the irq is shared.
*/
ret = devm_request_irq(dev, irq, int0002_irq,
IRQF_SHARED, "INT0002", chip);
if (ret) {
dev_err(dev, "Error requesting IRQ %d: %d\n", irq, ret);
return ret;
}
ret = gpiochip_irqchip_add(chip, &int0002_irqchip, 0, handle_edge_irq,
IRQ_TYPE_NONE);
if (ret) {
dev_err(dev, "Error adding irqchip: %d\n", ret);
return ret;
}
gpiochip_set_chained_irqchip(chip, &int0002_irqchip, irq, NULL);
return 0;
}
static const struct acpi_device_id int0002_acpi_ids[] = {
{ "INT0002", 0 },
{ },
};
MODULE_DEVICE_TABLE(acpi, int0002_acpi_ids);
static struct platform_driver int0002_driver = {
.driver = {
.name = DRV_NAME,
.acpi_match_table = int0002_acpi_ids,
},
.probe = int0002_probe,
};
module_platform_driver(int0002_driver);
MODULE_AUTHOR("Hans de Goede <hdegoede@redhat.com>");
MODULE_DESCRIPTION("Intel INT0002 Virtual GPIO driver");
MODULE_LICENSE("GPL");
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