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
int0002_gpio_get(struct gpio_chip * chip,unsigned int offset)59 static int int0002_gpio_get(struct gpio_chip *chip, unsigned int offset)
60 {
61 return 0;
62 }
63
int0002_gpio_set(struct gpio_chip * chip,unsigned int offset,int value)64 static void int0002_gpio_set(struct gpio_chip *chip, unsigned int offset,
65 int value)
66 {
67 }
68
int0002_gpio_direction_output(struct gpio_chip * chip,unsigned int offset,int value)69 static int int0002_gpio_direction_output(struct gpio_chip *chip,
70 unsigned int offset, int value)
71 {
72 return 0;
73 }
74
int0002_irq_ack(struct irq_data * data)75 static void int0002_irq_ack(struct irq_data *data)
76 {
77 outl(GPE0A_PME_B0_STS_BIT, GPE0A_STS_PORT);
78 }
79
int0002_irq_unmask(struct irq_data * data)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
int0002_irq_mask(struct irq_data * data)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
int0002_irq_set_wake(struct irq_data * data,unsigned int on)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
int0002_irq(int irq,void * data)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
int0002_check_wake(void * data)130 static bool int0002_check_wake(void *data)
131 {
132 u32 gpe_sts_reg;
133
134 gpe_sts_reg = inl(GPE0A_STS_PORT);
135 return (gpe_sts_reg & GPE0A_PME_B0_STS_BIT);
136 }
137
138 static struct irq_chip int0002_byt_irqchip = {
139 .name = DRV_NAME,
140 .irq_ack = int0002_irq_ack,
141 .irq_mask = int0002_irq_mask,
142 .irq_unmask = int0002_irq_unmask,
143 .irq_set_wake = int0002_irq_set_wake,
144 };
145
146 static struct irq_chip int0002_cht_irqchip = {
147 .name = DRV_NAME,
148 .irq_ack = int0002_irq_ack,
149 .irq_mask = int0002_irq_mask,
150 .irq_unmask = int0002_irq_unmask,
151 /*
152 * No set_wake, on CHT the IRQ is typically shared with the ACPI SCI
153 * and we don't want to mess with the ACPI SCI irq settings.
154 */
155 .flags = IRQCHIP_SKIP_SET_WAKE,
156 };
157
158 static const struct x86_cpu_id int0002_cpu_ids[] = {
159 X86_MATCH_INTEL_FAM6_MODEL(ATOM_SILVERMONT, &int0002_byt_irqchip),
160 X86_MATCH_INTEL_FAM6_MODEL(ATOM_AIRMONT, &int0002_cht_irqchip),
161 {}
162 };
163
int0002_init_irq_valid_mask(struct gpio_chip * chip,unsigned long * valid_mask,unsigned int ngpios)164 static void int0002_init_irq_valid_mask(struct gpio_chip *chip,
165 unsigned long *valid_mask,
166 unsigned int ngpios)
167 {
168 bitmap_clear(valid_mask, 0, GPE0A_PME_B0_VIRT_GPIO_PIN);
169 }
170
int0002_probe(struct platform_device * pdev)171 static int int0002_probe(struct platform_device *pdev)
172 {
173 struct device *dev = &pdev->dev;
174 const struct x86_cpu_id *cpu_id;
175 struct gpio_chip *chip;
176 struct gpio_irq_chip *girq;
177 int irq, ret;
178
179 /* Menlow has a different INT0002 device? <sigh> */
180 cpu_id = x86_match_cpu(int0002_cpu_ids);
181 if (!cpu_id)
182 return -ENODEV;
183
184 irq = platform_get_irq(pdev, 0);
185 if (irq < 0)
186 return irq;
187
188 chip = devm_kzalloc(dev, sizeof(*chip), GFP_KERNEL);
189 if (!chip)
190 return -ENOMEM;
191
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 = (struct irq_chip *)cpu_id->driver_data;
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 return 0;
234 }
235
int0002_remove(struct platform_device * pdev)236 static int int0002_remove(struct platform_device *pdev)
237 {
238 device_init_wakeup(&pdev->dev, false);
239 acpi_unregister_wakeup_handler(int0002_check_wake, NULL);
240 return 0;
241 }
242
243 static const struct acpi_device_id int0002_acpi_ids[] = {
244 { "INT0002", 0 },
245 { },
246 };
247 MODULE_DEVICE_TABLE(acpi, int0002_acpi_ids);
248
249 static struct platform_driver int0002_driver = {
250 .driver = {
251 .name = DRV_NAME,
252 .acpi_match_table = int0002_acpi_ids,
253 },
254 .probe = int0002_probe,
255 .remove = int0002_remove,
256 };
257
258 module_platform_driver(int0002_driver);
259
260 MODULE_AUTHOR("Hans de Goede <hdegoede@redhat.com>");
261 MODULE_DESCRIPTION("Intel INT0002 Virtual GPIO driver");
262 MODULE_LICENSE("GPL v2");
263