// SPDX-License-Identifier: GPL-2.0-only
/*
 * Driver for GE FPGA based GPIO
 *
 * Author: Martyn Welch <martyn.welch@ge.com>
 *
 * 2008 (c) GE Intelligent Platforms Embedded Systems, Inc.
 */

/*
 * TODO:
 *
 * Configuration of output modes (totem-pole/open-drain).
 * Interrupt configuration - interrupts are always generated, the FPGA relies
 * on the I/O interrupt controllers mask to stop them from being propagated.
 */

#include <linux/gpio/driver.h>
#include <linux/gpio/generic.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/property.h>
#include <linux/slab.h>

#define GEF_GPIO_DIRECT         0x00
#define GEF_GPIO_IN             0x04
#define GEF_GPIO_OUT            0x08
#define GEF_GPIO_TRIG           0x0C
#define GEF_GPIO_POLAR_A        0x10
#define GEF_GPIO_POLAR_B        0x14
#define GEF_GPIO_INT_STAT       0x18
#define GEF_GPIO_OVERRUN        0x1C
#define GEF_GPIO_MODE           0x20

static const struct of_device_id gef_gpio_ids[] = {
        {
                .compatible     = "gef,sbc610-gpio",
                .data           = (void *)19,
        }, {
                .compatible     = "gef,sbc310-gpio",
                .data           = (void *)6,
        }, {
                .compatible     = "ge,imp3a-gpio",
                .data           = (void *)16,
        },
        { }
};
MODULE_DEVICE_TABLE(of, gef_gpio_ids);

static int __init gef_gpio_probe(struct platform_device *pdev)
{
        struct gpio_generic_chip_config config;
        struct device *dev = &pdev->dev;
        struct gpio_generic_chip *chip;
        struct gpio_chip *gc;
        void __iomem *regs;
        int ret;

        chip = devm_kzalloc(dev, sizeof(*chip), GFP_KERNEL);
        if (!chip)
                return -ENOMEM;

        regs = devm_platform_ioremap_resource(pdev, 0);
        if (IS_ERR(regs))
                return PTR_ERR(regs);

        config = (struct gpio_generic_chip_config) {
                .dev = dev,
                .sz = 4,
                .dat = regs + GEF_GPIO_IN,
                .set = regs + GEF_GPIO_OUT,
                .dirin = regs + GEF_GPIO_DIRECT,
                .flags = GPIO_GENERIC_BIG_ENDIAN_BYTE_ORDER,
        };

        ret = gpio_generic_chip_init(chip, &config);
        if (ret)
                return dev_err_probe(dev, ret,
                                     "failed to initialize the generic GPIO chip\n");

        gc = &chip->gc;

        /* Setup pointers to chip functions */
        gc->label = devm_kasprintf(dev, GFP_KERNEL, "%pfw", dev_fwnode(dev));
        if (!gc->label)
                return -ENOMEM;

        gc->base = -1;
        gc->ngpio = (uintptr_t)device_get_match_data(dev);

        /* This function adds a memory mapped GPIO chip */
        ret = devm_gpiochip_add_data(dev, gc, NULL);
        if (ret)
                return dev_err_probe(dev, ret, "GPIO chip registration failed\n");

        return 0;
};

static struct platform_driver gef_gpio_driver = {
        .driver = {
                .name           = "gef-gpio",
                .of_match_table = gef_gpio_ids,
        },
};
module_platform_driver_probe(gef_gpio_driver, gef_gpio_probe);

MODULE_DESCRIPTION("GE I/O FPGA GPIO driver");
MODULE_AUTHOR("Martyn Welch <martyn.welch@ge.com>");
MODULE_LICENSE("GPL");