drivers/platform/x86/intel_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.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
  54 /*
  55  * As this is not a real GPIO at all, but just a hack to model an event in
  56  * ACPI the get / set functions are dummy functions.
  57  */
  58
  59 static int int0002_gpio_get(struct gpio_chip *chip, unsigned int offset)
  60 {
  61         return 0;
  62 }
  63
  64 static void int0002_gpio_set(struct gpio_chip *chip, unsigned int offset,
  65                              int value)
  66 {
  67 }
  68
  69 static int int0002_gpio_direction_output(struct gpio_chip *chip,
  70                                          unsigned int offset, int value)
  71 {
  72         return 0;
  73 }
  74
  75 static void int0002_irq_ack(struct irq_data *data)
  76 {
  77         outl(GPE0A_PME_B0_STS_BIT, GPE0A_STS_PORT);
  78 }
  79
  80 static void int0002_irq_unmask(struct irq_data *data)
  81 {
  82         u32 gpe_en_reg;
  83
  84         gpe_en_reg = inl(GPE0A_EN_PORT);
  85         gpe_en_reg |= GPE0A_PME_B0_EN_BIT;
  86         outl(gpe_en_reg, GPE0A_EN_PORT);
  87 }
  88
  89 static void int0002_irq_mask(struct irq_data *data)
  90 {
  91         u32 gpe_en_reg;
  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
  98 static int int0002_irq_set_wake(struct irq_data *data, unsigned int on)
  99 {
 100         struct gpio_chip *chip = irq_data_get_irq_chip_data(data);
 101         struct platform_device *pdev = to_platform_device(chip->parent);
 102         int irq = platform_get_irq(pdev, 0);
 103
 104         /* Propagate to parent irq */
 105         if (on)
 106                 enable_irq_wake(irq);
 107         else
 108                 disable_irq_wake(irq);
 109
 110         return 0;
 111 }
 112
 113 static 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_wakeup_hard_event(chip->parent);
 126
 127         return IRQ_HANDLED;
 128 }
 129
 130 static struct irq_chip int0002_byt_irqchip = {
 131         .name                   = DRV_NAME,
 132         .irq_ack                = int0002_irq_ack,
 133         .irq_mask               = int0002_irq_mask,
 134         .irq_unmask             = int0002_irq_unmask,
 135         .irq_set_wake           = int0002_irq_set_wake,
 136 };
 137
 138 static struct irq_chip int0002_cht_irqchip = {
 139         .name                   = DRV_NAME,
 140         .irq_ack                = int0002_irq_ack,
 141         .irq_mask               = int0002_irq_mask,
 142         .irq_unmask             = int0002_irq_unmask,
 143         /*
 144          * No set_wake, on CHT the IRQ is typically shared with the ACPI SCI
 145          * and we don't want to mess with the ACPI SCI irq settings.
 146          */
 147         .flags                  = IRQCHIP_SKIP_SET_WAKE,
 148 };
 149
 150 static const struct x86_cpu_id int0002_cpu_ids[] = {
 151         INTEL_CPU_FAM6(ATOM_SILVERMONT, int0002_byt_irqchip),   /* Valleyview, Bay Trail  */
 152         INTEL_CPU_FAM6(ATOM_AIRMONT, int0002_cht_irqchip),      /* Braswell, Cherry Trail */
 153         {}
 154 };
 155
 156 static void int0002_init_irq_valid_mask(struct gpio_chip *chip,
 157                                         unsigned long *valid_mask,
 158                                         unsigned int ngpios)
 159 {
 160         bitmap_clear(valid_mask, 0, GPE0A_PME_B0_VIRT_GPIO_PIN);
 161 }
 162
 163 static int int0002_probe(struct platform_device *pdev)
 164 {
 165         struct device *dev = &pdev->dev;
 166         const struct x86_cpu_id *cpu_id;
 167         struct gpio_chip *chip;
 168         struct gpio_irq_chip *girq;
 169         int irq, ret;
 170
 171         /* Menlow has a different INT0002 device? <sigh> */
 172         cpu_id = x86_match_cpu(int0002_cpu_ids);
 173         if (!cpu_id)
 174                 return -ENODEV;
 175
 176         irq = platform_get_irq(pdev, 0);
 177         if (irq < 0)
 178                 return irq;
 179
 180         chip = devm_kzalloc(dev, sizeof(*chip), GFP_KERNEL);
 181         if (!chip)
 182                 return -ENOMEM;
 183
 184         chip->label = DRV_NAME;
 185         chip->parent = dev;
 186         chip->owner = THIS_MODULE;
 187         chip->get = int0002_gpio_get;
 188         chip->set = int0002_gpio_set;
 189         chip->direction_input = int0002_gpio_get;
 190         chip->direction_output = int0002_gpio_direction_output;
 191         chip->base = -1;
 192         chip->ngpio = GPE0A_PME_B0_VIRT_GPIO_PIN + 1;
 193         chip->irq.init_valid_mask = int0002_init_irq_valid_mask;
 194
 195         /*
 196          * We directly request the irq here instead of passing a flow-handler
 197          * to gpiochip_set_chained_irqchip, because the irq is shared.
 198          * FIXME: augment this if we managed to pull handling of shared
 199          * IRQs into gpiolib.
 200          */
 201         ret = devm_request_irq(dev, irq, int0002_irq,
 202                                IRQF_SHARED, "INT0002", chip);
 203         if (ret) {
 204                 dev_err(dev, "Error requesting IRQ %d: %d\n", irq, ret);
 205                 return ret;
 206         }
 207
 208         girq = &chip->irq;
 209         girq->chip = (struct irq_chip *)cpu_id->driver_data;
 210         /* This let us handle the parent IRQ in the driver */
 211         girq->parent_handler = NULL;
 212         girq->num_parents = 0;
 213         girq->parents = NULL;
 214         girq->default_type = IRQ_TYPE_NONE;
 215         girq->handler = handle_edge_irq;
 216
 217         ret = devm_gpiochip_add_data(dev, chip, NULL);
 218         if (ret) {
 219                 dev_err(dev, "Error adding gpio chip: %d\n", ret);
 220                 return ret;
 221         }
 222
 223         device_init_wakeup(dev, true);
 224         return 0;
 225 }
 226
 227 static int int0002_remove(struct platform_device *pdev)
 228 {
 229         device_init_wakeup(&pdev->dev, false);
 230         return 0;
 231 }
 232
 233 static const struct acpi_device_id int0002_acpi_ids[] = {
 234         { "INT0002", 0 },
 235         { },
 236 };
 237 MODULE_DEVICE_TABLE(acpi, int0002_acpi_ids);
 238
 239 static struct platform_driver int0002_driver = {
 240         .driver = {
 241                 .name                   = DRV_NAME,
 242                 .acpi_match_table       = int0002_acpi_ids,
 243         },
 244         .probe  = int0002_probe,
 245         .remove = int0002_remove,
 246 };
 247
 248 module_platform_driver(int0002_driver);
 249
 250 MODULE_AUTHOR("Hans de Goede <hdegoede@redhat.com>");
 251 MODULE_DESCRIPTION("Intel INT0002 Virtual GPIO driver");
 252 MODULE_LICENSE("GPL v2");