// SPDX-License-Identifier: GPL-2.0-only
/*
 * AMD CS5535/CS5536 GPIO driver
 * Copyright (C) 2006  Advanced Micro Devices, Inc.
 * Copyright (C) 2007-2009  Andres Salomon <dilinger@collabora.co.uk>
 */

#include <linux/kernel.h>
#include <linux/spinlock.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/gpio/driver.h>
#include <linux/io.h>
#include <linux/cs5535.h>
#include <asm/msr.h>

#define DRV_NAME "cs5535-gpio"

/*
 * Some GPIO pins
 *  31-29,23 : reserved (always mask out)
 *  28       : Power Button
 *  26       : PME#
 *  22-16    : LPC
 *  14,15    : SMBus
 *  9,8      : UART1
 *  7        : PCI INTB
 *  3,4      : UART2/DDC
 *  2        : IDE_IRQ0
 *  1        : AC_BEEP
 *  0        : PCI INTA
 *
 * If a mask was not specified, allow all except
 * reserved and Power Button
 */
#define GPIO_DEFAULT_MASK 0x0F7FFFFF

static ulong mask = GPIO_DEFAULT_MASK;
module_param_named(mask, mask, ulong, 0444);
MODULE_PARM_DESC(mask, "GPIO channel mask.");

/*
 * FIXME: convert this singleton driver to use the state container
 * design pattern, see Documentation/driver-api/driver-model/design-patterns.rst
 */
static struct cs5535_gpio_chip {
        struct gpio_chip chip;
        resource_size_t base;

        struct platform_device *pdev;
        spinlock_t lock;
} cs5535_gpio_chip;

/*
 * The CS5535/CS5536 GPIOs support a number of extra features not defined
 * by the gpio_chip API, so these are exported.  For a full list of the
 * registers, see include/linux/cs5535.h.
 */

static void errata_outl(struct cs5535_gpio_chip *chip, u32 val,
                unsigned int reg)
{
        unsigned long addr = chip->base + 0x80 + reg;

        /*
         * According to the CS5536 errata (#36), after suspend
         * a write to the high bank GPIO register will clear all
         * non-selected bits; the recommended workaround is a
         * read-modify-write operation.
         *
         * Don't apply this errata to the edge status GPIOs, as writing
         * to their lower bits will clear them.
         */
        if (reg != GPIO_POSITIVE_EDGE_STS && reg != GPIO_NEGATIVE_EDGE_STS) {
                if (val & 0xffff)
                        val |= (inl(addr) & 0xffff); /* ignore the high bits */
                else
                        val |= (inl(addr) ^ (val >> 16));
        }
        outl(val, addr);
}

static void __cs5535_gpio_set(struct cs5535_gpio_chip *chip, unsigned offset,
                unsigned int reg)
{
        if (offset < 16)
                /* low bank register */
                outl(1 << offset, chip->base + reg);
        else
                /* high bank register */
                errata_outl(chip, 1 << (offset - 16), reg);
}

void cs5535_gpio_set(unsigned offset, unsigned int reg)
{
        struct cs5535_gpio_chip *chip = &cs5535_gpio_chip;
        unsigned long flags;

        spin_lock_irqsave(&chip->lock, flags);
        __cs5535_gpio_set(chip, offset, reg);
        spin_unlock_irqrestore(&chip->lock, flags);
}
EXPORT_SYMBOL_GPL(cs5535_gpio_set);

static void __cs5535_gpio_clear(struct cs5535_gpio_chip *chip, unsigned offset,
                unsigned int reg)
{
        if (offset < 16)
                /* low bank register */
                outl(1 << (offset + 16), chip->base + reg);
        else
                /* high bank register */
                errata_outl(chip, 1 << offset, reg);
}

void cs5535_gpio_clear(unsigned offset, unsigned int reg)
{
        struct cs5535_gpio_chip *chip = &cs5535_gpio_chip;
        unsigned long flags;

        spin_lock_irqsave(&chip->lock, flags);
        __cs5535_gpio_clear(chip, offset, reg);
        spin_unlock_irqrestore(&chip->lock, flags);
}
EXPORT_SYMBOL_GPL(cs5535_gpio_clear);

int cs5535_gpio_isset(unsigned offset, unsigned int reg)
{
        struct cs5535_gpio_chip *chip = &cs5535_gpio_chip;
        unsigned long flags;
        long val;

        spin_lock_irqsave(&chip->lock, flags);
        if (offset < 16)
                /* low bank register */
                val = inl(chip->base + reg);
        else {
                /* high bank register */
                val = inl(chip->base + 0x80 + reg);
                offset -= 16;
        }
        spin_unlock_irqrestore(&chip->lock, flags);

        return (val & (1 << offset)) ? 1 : 0;
}
EXPORT_SYMBOL_GPL(cs5535_gpio_isset);

int cs5535_gpio_set_irq(unsigned group, unsigned irq)
{
        uint32_t lo, hi;

        if (group > 7 || irq > 15)
                return -EINVAL;

        rdmsr(MSR_PIC_ZSEL_HIGH, lo, hi);

        lo &= ~(0xF << (group * 4));
        lo |= (irq & 0xF) << (group * 4);

        wrmsr(MSR_PIC_ZSEL_HIGH, lo, hi);
        return 0;
}
EXPORT_SYMBOL_GPL(cs5535_gpio_set_irq);

void cs5535_gpio_setup_event(unsigned offset, int pair, int pme)
{
        struct cs5535_gpio_chip *chip = &cs5535_gpio_chip;
        uint32_t shift = (offset % 8) * 4;
        unsigned long flags;
        uint32_t val;

        if (offset >= 24)
                offset = GPIO_MAP_W;
        else if (offset >= 16)
                offset = GPIO_MAP_Z;
        else if (offset >= 8)
                offset = GPIO_MAP_Y;
        else
                offset = GPIO_MAP_X;

        spin_lock_irqsave(&chip->lock, flags);
        val = inl(chip->base + offset);

        /* Clear whatever was there before */
        val &= ~(0xF << shift);

        /* Set the new value */
        val |= ((pair & 7) << shift);

        /* Set the PME bit if this is a PME event */
        if (pme)
                val |= (1 << (shift + 3));

        outl(val, chip->base + offset);
        spin_unlock_irqrestore(&chip->lock, flags);
}
EXPORT_SYMBOL_GPL(cs5535_gpio_setup_event);

/*
 * Generic gpio_chip API support.
 */

static int chip_gpio_request(struct gpio_chip *c, unsigned offset)
{
        struct cs5535_gpio_chip *chip = gpiochip_get_data(c);
        unsigned long flags;

        spin_lock_irqsave(&chip->lock, flags);

        /* check if this pin is available */
        if ((mask & (1 << offset)) == 0) {
                dev_info(&chip->pdev->dev,
                        "pin %u is not available (check mask)\n", offset);
                spin_unlock_irqrestore(&chip->lock, flags);
                return -EINVAL;
        }

        /* disable output aux 1 & 2 on this pin */
        __cs5535_gpio_clear(chip, offset, GPIO_OUTPUT_AUX1);
        __cs5535_gpio_clear(chip, offset, GPIO_OUTPUT_AUX2);

        /* disable input aux 1 on this pin */
        __cs5535_gpio_clear(chip, offset, GPIO_INPUT_AUX1);

        spin_unlock_irqrestore(&chip->lock, flags);

        return 0;
}

static int chip_gpio_get(struct gpio_chip *chip, unsigned offset)
{
        return cs5535_gpio_isset(offset, GPIO_READ_BACK);
}

static void chip_gpio_set(struct gpio_chip *chip, unsigned offset, int val)
{
        if (val)
                cs5535_gpio_set(offset, GPIO_OUTPUT_VAL);
        else
                cs5535_gpio_clear(offset, GPIO_OUTPUT_VAL);
}

static int chip_direction_input(struct gpio_chip *c, unsigned offset)
{
        struct cs5535_gpio_chip *chip = gpiochip_get_data(c);
        unsigned long flags;

        spin_lock_irqsave(&chip->lock, flags);
        __cs5535_gpio_set(chip, offset, GPIO_INPUT_ENABLE);
        __cs5535_gpio_clear(chip, offset, GPIO_OUTPUT_ENABLE);
        spin_unlock_irqrestore(&chip->lock, flags);

        return 0;
}

static int chip_direction_output(struct gpio_chip *c, unsigned offset, int val)
{
        struct cs5535_gpio_chip *chip = gpiochip_get_data(c);
        unsigned long flags;

        spin_lock_irqsave(&chip->lock, flags);

        __cs5535_gpio_set(chip, offset, GPIO_INPUT_ENABLE);
        __cs5535_gpio_set(chip, offset, GPIO_OUTPUT_ENABLE);
        if (val)
                __cs5535_gpio_set(chip, offset, GPIO_OUTPUT_VAL);
        else
                __cs5535_gpio_clear(chip, offset, GPIO_OUTPUT_VAL);

        spin_unlock_irqrestore(&chip->lock, flags);

        return 0;
}

static const char * const cs5535_gpio_names[] = {
        "GPIO0", "GPIO1", "GPIO2", "GPIO3",
        "GPIO4", "GPIO5", "GPIO6", "GPIO7",
        "GPIO8", "GPIO9", "GPIO10", "GPIO11",
        "GPIO12", "GPIO13", "GPIO14", "GPIO15",
        "GPIO16", "GPIO17", "GPIO18", "GPIO19",
        "GPIO20", "GPIO21", "GPIO22", NULL,
        "GPIO24", "GPIO25", "GPIO26", "GPIO27",
        "GPIO28", NULL, NULL, NULL,
};

static struct cs5535_gpio_chip cs5535_gpio_chip = {
        .chip = {
                .owner = THIS_MODULE,
                .label = DRV_NAME,

                .base = 0,
                .ngpio = 32,
                .names = cs5535_gpio_names,
                .request = chip_gpio_request,

                .get = chip_gpio_get,
                .set = chip_gpio_set,

                .direction_input = chip_direction_input,
                .direction_output = chip_direction_output,
        },
};

static int cs5535_gpio_probe(struct platform_device *pdev)
{
        struct resource *res;
        int err = -EIO;
        ulong mask_orig = mask;

        /* There are two ways to get the GPIO base address; one is by
         * fetching it from MSR_LBAR_GPIO, the other is by reading the
         * PCI BAR info.  The latter method is easier (especially across
         * different architectures), so we'll stick with that for now.  If
         * it turns out to be unreliable in the face of crappy BIOSes, we
         * can always go back to using MSRs.. */

        res = platform_get_resource(pdev, IORESOURCE_IO, 0);
        if (!res) {
                dev_err(&pdev->dev, "can't fetch device resource info\n");
                return err;
        }

        if (!devm_request_region(&pdev->dev, res->start, resource_size(res),
                                 pdev->name)) {
                dev_err(&pdev->dev, "can't request region\n");
                return err;
        }

        /* set up the driver-specific struct */
        cs5535_gpio_chip.base = res->start;
        cs5535_gpio_chip.pdev = pdev;
        spin_lock_init(&cs5535_gpio_chip.lock);

        dev_info(&pdev->dev, "reserved resource region %pR\n", res);

        /* mask out reserved pins */
        mask &= 0x1F7FFFFF;

        /* do not allow pin 28, Power Button, as there's special handling
         * in the PMC needed. (note 12, p. 48) */
        mask &= ~(1 << 28);

        if (mask_orig != mask)
                dev_info(&pdev->dev, "mask changed from 0x%08lX to 0x%08lX\n",
                                mask_orig, mask);

        /* finally, register with the generic GPIO API */
        return devm_gpiochip_add_data(&pdev->dev, &cs5535_gpio_chip.chip,
                                      &cs5535_gpio_chip);
}

static struct platform_driver cs5535_gpio_driver = {
        .driver = {
                .name = DRV_NAME,
        },
        .probe = cs5535_gpio_probe,
};

module_platform_driver(cs5535_gpio_driver);

MODULE_AUTHOR("Andres Salomon <dilinger@queued.net>");
MODULE_DESCRIPTION("AMD CS5535/CS5536 GPIO driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:" DRV_NAME);