1/*
  2 * AMD Promontory GPIO driver
  3 *
  4 * Copyright (C) 2015 ASMedia Technology Inc.
  5 * Author: YD Tseng <yd_tseng@asmedia.com.tw>
  6 *
  7 * This program is free software; you can redistribute it and/or modify
  8 * it under the terms of the GNU General Public License version 2 as
  9 * published by the Free Software Foundation.
 10 */
 11
 12#include <linux/kernel.h>
 13#include <linux/module.h>
 14#include <linux/gpio/driver.h>
 15#include <linux/spinlock.h>
 16#include <linux/acpi.h>
 17#include <linux/platform_device.h>
 18
 19#define PT_TOTAL_GPIO 8
 20
 21/* PCI-E MMIO register offsets */
 22#define PT_DIRECTION_REG   0x00
 23#define PT_INPUTDATA_REG   0x04
 24#define PT_OUTPUTDATA_REG  0x08
 25#define PT_CLOCKRATE_REG   0x0C
 26#define PT_SYNC_REG        0x28
 27
 28struct pt_gpio_chip {
 29	struct gpio_chip         gc;
 30	void __iomem             *reg_base;
 31};
 32
 33static int pt_gpio_request(struct gpio_chip *gc, unsigned offset)
 34{
 35	struct pt_gpio_chip *pt_gpio = gpiochip_get_data(gc);
 36	unsigned long flags;
 37	u32 using_pins;
 38
 39	dev_dbg(gc->parent, "pt_gpio_request offset=%x\n", offset);
 40
 41	spin_lock_irqsave(&gc->bgpio_lock, flags);
 42
 43	using_pins = readl(pt_gpio->reg_base + PT_SYNC_REG);
 44	if (using_pins & BIT(offset)) {
 45		dev_warn(gc->parent, "PT GPIO pin %x reconfigured\n",
 46			 offset);
 47		spin_unlock_irqrestore(&gc->bgpio_lock, flags);
 48		return -EINVAL;
 49	}
 50
 51	writel(using_pins | BIT(offset), pt_gpio->reg_base + PT_SYNC_REG);
 52
 53	spin_unlock_irqrestore(&gc->bgpio_lock, flags);
 54
 55	return 0;
 56}
 57
 58static void pt_gpio_free(struct gpio_chip *gc, unsigned offset)
 59{
 60	struct pt_gpio_chip *pt_gpio = gpiochip_get_data(gc);
 61	unsigned long flags;
 62	u32 using_pins;
 63
 64	spin_lock_irqsave(&gc->bgpio_lock, flags);
 65
 66	using_pins = readl(pt_gpio->reg_base + PT_SYNC_REG);
 67	using_pins &= ~BIT(offset);
 68	writel(using_pins, pt_gpio->reg_base + PT_SYNC_REG);
 69
 70	spin_unlock_irqrestore(&gc->bgpio_lock, flags);
 71
 72	dev_dbg(gc->parent, "pt_gpio_free offset=%x\n", offset);
 73}
 74
 75static int pt_gpio_probe(struct platform_device *pdev)
 76{
 77	struct device *dev = &pdev->dev;
 78	struct acpi_device *acpi_dev;
 79	acpi_handle handle = ACPI_HANDLE(dev);
 80	struct pt_gpio_chip *pt_gpio;
 81	struct resource *res_mem;
 82	int ret = 0;
 83
 84	if (acpi_bus_get_device(handle, &acpi_dev)) {
 85		dev_err(dev, "PT GPIO device node not found\n");
 86		return -ENODEV;
 87	}
 88
 89	pt_gpio = devm_kzalloc(dev, sizeof(struct pt_gpio_chip), GFP_KERNEL);
 90	if (!pt_gpio)
 91		return -ENOMEM;
 92
 93	res_mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 94	if (!res_mem) {
 95		dev_err(&pdev->dev, "Failed to get MMIO resource for PT GPIO.\n");
 96		return -EINVAL;
 97	}
 98	pt_gpio->reg_base = devm_ioremap_resource(dev, res_mem);
 99	if (IS_ERR(pt_gpio->reg_base)) {
100		dev_err(&pdev->dev, "Failed to map MMIO resource for PT GPIO.\n");
101		return PTR_ERR(pt_gpio->reg_base);
102	}
103
104	ret = bgpio_init(&pt_gpio->gc, dev, 4,
105			 pt_gpio->reg_base + PT_INPUTDATA_REG,
106			 pt_gpio->reg_base + PT_OUTPUTDATA_REG, NULL,
107			 pt_gpio->reg_base + PT_DIRECTION_REG, NULL,
108			 BGPIOF_READ_OUTPUT_REG_SET);
109	if (ret) {
110		dev_err(&pdev->dev, "bgpio_init failed\n");
111		return ret;
112	}
113
114	pt_gpio->gc.owner            = THIS_MODULE;
115	pt_gpio->gc.request          = pt_gpio_request;
116	pt_gpio->gc.free             = pt_gpio_free;
117	pt_gpio->gc.ngpio            = PT_TOTAL_GPIO;
118#if defined(CONFIG_OF_GPIO)
119	pt_gpio->gc.of_node          = pdev->dev.of_node;
120#endif
121	ret = gpiochip_add_data(&pt_gpio->gc, pt_gpio);
122	if (ret) {
123		dev_err(&pdev->dev, "Failed to register GPIO lib\n");
124		return ret;
125	}
126
127	platform_set_drvdata(pdev, pt_gpio);
128
129	/* initialize register setting */
130	writel(0, pt_gpio->reg_base + PT_SYNC_REG);
131	writel(0, pt_gpio->reg_base + PT_CLOCKRATE_REG);
132
133	dev_dbg(&pdev->dev, "PT GPIO driver loaded\n");
134	return ret;
135}
136
137static int pt_gpio_remove(struct platform_device *pdev)
138{
139	struct pt_gpio_chip *pt_gpio = platform_get_drvdata(pdev);
140
141	gpiochip_remove(&pt_gpio->gc);
142
143	return 0;
144}
145
146static const struct acpi_device_id pt_gpio_acpi_match[] = {
147	{ "AMDF030", 0 },
148	{ "AMDIF030", 0 },
149	{ },
150};
151MODULE_DEVICE_TABLE(acpi, pt_gpio_acpi_match);
152
153static struct platform_driver pt_gpio_driver = {
154	.driver = {
155		.name = "pt-gpio",
156		.acpi_match_table = ACPI_PTR(pt_gpio_acpi_match),
157	},
158	.probe = pt_gpio_probe,
159	.remove = pt_gpio_remove,
160};
161
162module_platform_driver(pt_gpio_driver);
163
164MODULE_LICENSE("GPL");
165MODULE_AUTHOR("YD Tseng <yd_tseng@asmedia.com.tw>");
166MODULE_DESCRIPTION("AMD Promontory GPIO Driver");