// SPDX-License-Identifier: GPL-2.0-only
/*
 * Support for viafb GPIO ports.
 *
 * Copyright 2009 Jonathan Corbet <corbet@lwn.net>
 */

#include <linux/spinlock.h>
#include <linux/gpio/driver.h>
#include <linux/gpio/machine.h>
#include <linux/platform_device.h>
#include <linux/via-core.h>
#include "via-gpio.h"

/*
 * The ports we know about.  Note that the port-25 gpios are not
 * mentioned in the datasheet.
 */

struct viafb_gpio {
        char *vg_name;  /* Data sheet name */
        u16 vg_io_port;
        u8  vg_port_index;
        int  vg_mask_shift;
};

static struct viafb_gpio viafb_all_gpios[] = {
        {
                .vg_name = "VGPIO0",  /* Guess - not in datasheet */
                .vg_io_port = VIASR,
                .vg_port_index = 0x25,
                .vg_mask_shift = 1
        },
        {
                .vg_name = "VGPIO1",
                .vg_io_port = VIASR,
                .vg_port_index = 0x25,
                .vg_mask_shift = 0
        },
        {
                .vg_name = "VGPIO2",  /* aka DISPCLKI0 */
                .vg_io_port = VIASR,
                .vg_port_index = 0x2c,
                .vg_mask_shift = 1
        },
        {
                .vg_name = "VGPIO3",  /* aka DISPCLKO0 */
                .vg_io_port = VIASR,
                .vg_port_index = 0x2c,
                .vg_mask_shift = 0
        },
        {
                .vg_name = "VGPIO4",  /* DISPCLKI1 */
                .vg_io_port = VIASR,
                .vg_port_index = 0x3d,
                .vg_mask_shift = 1
        },
        {
                .vg_name = "VGPIO5",  /* DISPCLKO1 */
                .vg_io_port = VIASR,
                .vg_port_index = 0x3d,
                .vg_mask_shift = 0
        },
};

#define VIAFB_NUM_GPIOS ARRAY_SIZE(viafb_all_gpios)

/*
 * This structure controls the active GPIOs, which may be a subset
 * of those which are known.
 */

struct viafb_gpio_cfg {
        struct gpio_chip gpio_chip;
        struct viafb_dev *vdev;
        struct viafb_gpio *active_gpios[VIAFB_NUM_GPIOS];
        const char *gpio_names[VIAFB_NUM_GPIOS];
};

/*
 * GPIO access functions
 */
static int via_gpio_set(struct gpio_chip *chip, unsigned int nr, int value)
{
        struct viafb_gpio_cfg *cfg = gpiochip_get_data(chip);
        u8 reg;
        struct viafb_gpio *gpio;
        unsigned long flags;

        spin_lock_irqsave(&cfg->vdev->reg_lock, flags);
        gpio = cfg->active_gpios[nr];
        reg = via_read_reg(VIASR, gpio->vg_port_index);
        reg |= 0x40 << gpio->vg_mask_shift;  /* output enable */
        if (value)
                reg |= 0x10 << gpio->vg_mask_shift;
        else
                reg &= ~(0x10 << gpio->vg_mask_shift);
        via_write_reg(VIASR, gpio->vg_port_index, reg);
        spin_unlock_irqrestore(&cfg->vdev->reg_lock, flags);

        return 0;
}

static int via_gpio_dir_out(struct gpio_chip *chip, unsigned int nr,
                            int value)
{
        return via_gpio_set(chip, nr, value);
}

/*
 * Set the input direction.  I'm not sure this is right; we should
 * be able to do input without disabling output.
 */
static int via_gpio_dir_input(struct gpio_chip *chip, unsigned int nr)
{
        struct viafb_gpio_cfg *cfg = gpiochip_get_data(chip);
        struct viafb_gpio *gpio;
        unsigned long flags;

        spin_lock_irqsave(&cfg->vdev->reg_lock, flags);
        gpio = cfg->active_gpios[nr];
        via_write_reg_mask(VIASR, gpio->vg_port_index, 0,
                        0x40 << gpio->vg_mask_shift);
        spin_unlock_irqrestore(&cfg->vdev->reg_lock, flags);
        return 0;
}

static int via_gpio_get(struct gpio_chip *chip, unsigned int nr)
{
        struct viafb_gpio_cfg *cfg = gpiochip_get_data(chip);
        u8 reg;
        struct viafb_gpio *gpio;
        unsigned long flags;

        spin_lock_irqsave(&cfg->vdev->reg_lock, flags);
        gpio = cfg->active_gpios[nr];
        reg = via_read_reg(VIASR, gpio->vg_port_index);
        spin_unlock_irqrestore(&cfg->vdev->reg_lock, flags);
        return !!(reg & (0x04 << gpio->vg_mask_shift));
}


static struct viafb_gpio_cfg viafb_gpio_config = {
        .gpio_chip = {
                .label = "VIAFB onboard GPIO",
                .owner = THIS_MODULE,
                .direction_output = via_gpio_dir_out,
                .set = via_gpio_set,
                .direction_input = via_gpio_dir_input,
                .get = via_gpio_get,
                .base = -1,
                .ngpio = 0,
                .can_sleep = 0
        }
};

/*
 * Manage the software enable bit.
 */
static void viafb_gpio_enable(struct viafb_gpio *gpio)
{
        via_write_reg_mask(VIASR, gpio->vg_port_index, 0x02, 0x02);
}

static void viafb_gpio_disable(struct viafb_gpio *gpio)
{
        via_write_reg_mask(VIASR, gpio->vg_port_index, 0, 0x02);
}

#ifdef CONFIG_PM

static int viafb_gpio_suspend(void *private)
{
        return 0;
}

static int viafb_gpio_resume(void *private)
{
        int i;

        for (i = 0; i < viafb_gpio_config.gpio_chip.ngpio; i += 2)
                viafb_gpio_enable(viafb_gpio_config.active_gpios[i]);
        return 0;
}

static struct viafb_pm_hooks viafb_gpio_pm_hooks = {
        .suspend = viafb_gpio_suspend,
        .resume = viafb_gpio_resume
};
#endif /* CONFIG_PM */

static struct gpiod_lookup_table viafb_gpio_table = {
        .dev_id = "viafb-camera",
        .table = {
                GPIO_LOOKUP("via-gpio", 2, "VGPIO2", GPIO_ACTIVE_LOW),
                GPIO_LOOKUP("via-gpio", 3, "VGPIO3", GPIO_ACTIVE_HIGH),
                { }
        },
};

/*
 * Platform device stuff.
 */
static int viafb_gpio_probe(struct platform_device *platdev)
{
        struct viafb_dev *vdev = platdev->dev.platform_data;
        struct via_port_cfg *port_cfg = vdev->port_cfg;
        int i, ngpio = 0, ret;
        struct viafb_gpio *gpio;
        unsigned long flags;

        /*
         * Set up entries for all GPIOs which have been configured to
         * operate as such (as opposed to as i2c ports).
         */
        for (i = 0; i < VIAFB_NUM_PORTS; i++) {
                if (port_cfg[i].mode != VIA_MODE_GPIO)
                        continue;
                for (gpio = viafb_all_gpios;
                     gpio < viafb_all_gpios + VIAFB_NUM_GPIOS; gpio++)
                        if (gpio->vg_port_index == port_cfg[i].ioport_index) {
                                viafb_gpio_config.active_gpios[ngpio] = gpio;
                                viafb_gpio_config.gpio_names[ngpio] =
                                        gpio->vg_name;
                                ngpio++;
                        }
        }
        viafb_gpio_config.gpio_chip.ngpio = ngpio;
        viafb_gpio_config.gpio_chip.names = viafb_gpio_config.gpio_names;
        viafb_gpio_config.vdev = vdev;
        if (ngpio == 0) {
                printk(KERN_INFO "viafb: no GPIOs configured\n");
                return 0;
        }
        /*
         * Enable the ports.  They come in pairs, with a single
         * enable bit for both.
         */
        spin_lock_irqsave(&viafb_gpio_config.vdev->reg_lock, flags);
        for (i = 0; i < ngpio; i += 2)
                viafb_gpio_enable(viafb_gpio_config.active_gpios[i]);
        spin_unlock_irqrestore(&viafb_gpio_config.vdev->reg_lock, flags);
        /*
         * Get registered.
         */
        viafb_gpio_config.gpio_chip.base = -1;  /* Dynamic */
        viafb_gpio_config.gpio_chip.label = "via-gpio";
        ret = gpiochip_add_data(&viafb_gpio_config.gpio_chip,
                                &viafb_gpio_config);
        if (ret) {
                printk(KERN_ERR "viafb: failed to add gpios (%d)\n", ret);
                viafb_gpio_config.gpio_chip.ngpio = 0;
        }

        gpiod_add_lookup_table(&viafb_gpio_table);

#ifdef CONFIG_PM
        viafb_pm_register(&viafb_gpio_pm_hooks);
#endif
        return ret;
}


static void viafb_gpio_remove(struct platform_device *platdev)
{
        unsigned long flags;
        int i;

#ifdef CONFIG_PM
        viafb_pm_unregister(&viafb_gpio_pm_hooks);
#endif

        /*
         * Get unregistered.
         */
        if (viafb_gpio_config.gpio_chip.ngpio > 0) {
                gpiochip_remove(&viafb_gpio_config.gpio_chip);
        }
        /*
         * Disable the ports.
         */
        spin_lock_irqsave(&viafb_gpio_config.vdev->reg_lock, flags);
        for (i = 0; i < viafb_gpio_config.gpio_chip.ngpio; i += 2)
                viafb_gpio_disable(viafb_gpio_config.active_gpios[i]);
        viafb_gpio_config.gpio_chip.ngpio = 0;
        spin_unlock_irqrestore(&viafb_gpio_config.vdev->reg_lock, flags);
}

static struct platform_driver via_gpio_driver = {
        .driver = {
                .name = "viafb-gpio",
        },
        .probe = viafb_gpio_probe,
        .remove = viafb_gpio_remove,
};

int viafb_gpio_init(void)
{
        return platform_driver_register(&via_gpio_driver);
}

void viafb_gpio_exit(void)
{
        platform_driver_unregister(&via_gpio_driver);
}