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/*
 * GPIO driver for NCT5104D
 *
 * Author: Tasanakorn Phaipool <tasanakorn@gmail.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/platform_device.h>
#include <linux/io.h>
#include <linux/gpio.h>
#include <linux/version.h>
#include <linux/dmi.h>
#include <linux/string.h>

#define DRVNAME "gpio-nct5104d"

/*
 * Super-I/O registers
 */
#define SIO_LDSEL               0x07    /* Logical device select */
#define SIO_CHIPID              0x20    /* Chaip ID (2 bytes) */
#define SIO_GPIO_ENABLE 0x30    /* GPIO enable */
#define SIO_GPIO1_MODE          0xE0    /* GPIO1 Mode OpenDrain/Push-Pull */
#define SIO_GPIO2_MODE          0xE1    /* GPIO2 Mode OpenDrain/Push-Pull */

#define SIO_LD_GPIO             0x07    /* GPIO logical device */
#define SIO_LD_GPIO_MODE        0x0F    /* GPIO mode control device */
#define SIO_UNLOCK_KEY          0x87    /* Key to enable Super-I/O */
#define SIO_LOCK_KEY            0xAA    /* Key to disable Super-I/O */

#define SIO_NCT5104D_ID                                 0x1061  /* Chip ID */
#define SIO_PCENGINES_APU_NCT5104D_ID1  0xc452  /* Chip ID */
#define SIO_PCENGINES_APU_NCT5104D_ID2  0xc453  /* Chip ID */

enum chips { nct5104d };

static const char * const nct5104d_names[] = {
        "nct5104d"
};

struct nct5104d_sio {
        int addr;
        enum chips type;
};

struct nct5104d_gpio_bank {
        struct gpio_chip chip;
        unsigned int regbase;
        struct nct5104d_gpio_data *data;
};

struct nct5104d_gpio_data {
        struct nct5104d_sio *sio;
        int nr_bank;
        struct nct5104d_gpio_bank *bank;
};

/*
 * Super-I/O functions.
 */

static inline int superio_inb(int base, int reg)
{
        outb(reg, base);
        return inb(base + 1);
}

static int superio_inw(int base, int reg)
{
        int val;

        outb(reg++, base);
        val = inb(base + 1) << 8;
        outb(reg, base);
        val |= inb(base + 1);

        return val;
}

static inline void superio_outb(int base, int reg, int val)
{
        outb(reg, base);
        outb(val, base + 1);
}

static inline int superio_enter(int base)
{
        /* Don't step on other drivers' I/O space by accident. */
        if (!request_muxed_region(base, 2, DRVNAME)) {
                pr_err(DRVNAME "I/O address 0x%04x already in use\n", base);
                return -EBUSY;
        }

        /* According to the datasheet the key must be send twice. */
        outb(SIO_UNLOCK_KEY, base);
        outb(SIO_UNLOCK_KEY, base);

        return 0;
}

static inline void superio_select(int base, int ld)
{
        outb(SIO_LDSEL, base);
        outb(ld, base + 1);
}

static inline void superio_exit(int base)
{
        outb(SIO_LOCK_KEY, base);
        release_region(base, 2);
}

/*
 * GPIO chip.
 */

static int nct5104d_gpio_direction_in(struct gpio_chip *chip, unsigned offset);
static int nct5104d_gpio_get(struct gpio_chip *chip, unsigned offset);
static int nct5104d_gpio_direction_out(struct gpio_chip *chip,
                                     unsigned offset, int value);
static void nct5104d_gpio_set(struct gpio_chip *chip, unsigned offset, int value);

#define NCT5104D_GPIO_BANK(_base, _ngpio, _regbase)                     \
        {                                                               \
                .chip = {                                               \
                        .label            = DRVNAME,                    \
                        .owner            = THIS_MODULE,                \
                        .direction_input  = nct5104d_gpio_direction_in, \
                        .get              = nct5104d_gpio_get,          \
                        .direction_output = nct5104d_gpio_direction_out,        \
                        .set              = nct5104d_gpio_set,          \
                        .base             = _base,                      \
                        .ngpio            = _ngpio,                     \
                        .can_sleep        = true,                       \
                },                                                      \
                .regbase = _regbase,                                    \
        }

#define gpio_dir(base) (base + 0)
#define gpio_data(base) (base + 1)

static struct nct5104d_gpio_bank nct5104d_gpio_bank[] = {
        NCT5104D_GPIO_BANK(0 , 8, 0xE0),
        NCT5104D_GPIO_BANK(10, 8, 0xE4)
};

static int nct5104d_gpio_direction_in(struct gpio_chip *chip, unsigned offset)
{
        int err;
        struct nct5104d_gpio_bank *bank =
                container_of(chip, struct nct5104d_gpio_bank, chip);
        struct nct5104d_sio *sio = bank->data->sio;
        u8 dir;

        err = superio_enter(sio->addr);
        if (err)
                return err;
        superio_select(sio->addr, SIO_LD_GPIO);

        dir = superio_inb(sio->addr, gpio_dir(bank->regbase));
        dir |= (1 << offset);
        superio_outb(sio->addr, gpio_dir(bank->regbase), dir);

        superio_exit(sio->addr);

        return 0;
}

static int nct5104d_gpio_get(struct gpio_chip *chip, unsigned offset)
{
        int err;
        struct nct5104d_gpio_bank *bank =
                container_of(chip, struct nct5104d_gpio_bank, chip);
        struct nct5104d_sio *sio = bank->data->sio;
        u8 data;

        err = superio_enter(sio->addr);
        if (err)
                return err;
        superio_select(sio->addr, SIO_LD_GPIO);

        data = superio_inb(sio->addr, gpio_data(bank->regbase));

        superio_exit(sio->addr);

        return !!(data & 1 << offset);
}

static int nct5104d_gpio_direction_out(struct gpio_chip *chip,
                                     unsigned offset, int value)
{
        int err;
        struct nct5104d_gpio_bank *bank =
                container_of(chip, struct nct5104d_gpio_bank, chip);
        struct nct5104d_sio *sio = bank->data->sio;
        u8 dir, data_out;

        err = superio_enter(sio->addr);
        if (err)
                return err;
        superio_select(sio->addr, SIO_LD_GPIO);

        data_out = superio_inb(sio->addr, gpio_data(bank->regbase));
        if (value)
                data_out |= (1 << offset);
        else
                data_out &= ~(1 << offset);
        superio_outb(sio->addr, gpio_data(bank->regbase), data_out);

        dir = superio_inb(sio->addr, gpio_dir(bank->regbase));
        dir &= ~(1 << offset);
        superio_outb(sio->addr, gpio_dir(bank->regbase), dir);

        superio_exit(sio->addr);

        return 0;
}

static void nct5104d_gpio_set(struct gpio_chip *chip, unsigned offset, int value)
{
        int err;
        struct nct5104d_gpio_bank *bank =
                container_of(chip, struct nct5104d_gpio_bank, chip);
        struct nct5104d_sio *sio = bank->data->sio;
        u8 data_out;

        err = superio_enter(sio->addr);
        if (err)
                return;
        superio_select(sio->addr, SIO_LD_GPIO);

        data_out = superio_inb(sio->addr, gpio_data(bank->regbase));
        if (value)
                data_out |= (1 << offset);
        else
                data_out &= ~(1 << offset);
        superio_outb(sio->addr, gpio_data(bank->regbase), data_out);

        superio_exit(sio->addr);
}

/*
 * Platform device and driver.
 */

static int nct5104d_gpio_probe(struct platform_device *pdev)
{
        int err;
        int i;
        struct nct5104d_sio *sio = pdev->dev.platform_data;
        struct nct5104d_gpio_data *data;

        data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
        if (!data)
                return -ENOMEM;

        switch (sio->type) {
        case nct5104d:
                data->nr_bank = ARRAY_SIZE(nct5104d_gpio_bank);
                data->bank = nct5104d_gpio_bank;
                break;
        default:
                return -ENODEV;
        }
        data->sio = sio;

        platform_set_drvdata(pdev, data);

        /* For each GPIO bank, register a GPIO chip. */
        for (i = 0; i < data->nr_bank; i++) {
                struct nct5104d_gpio_bank *bank = &data->bank[i];

#if LINUX_VERSION_CODE < KERNEL_VERSION(4,5,0)
                bank->chip.dev = &pdev->dev;
#else
                bank->chip.parent = &pdev->dev;
#endif
                bank->data = data;

                err = gpiochip_add(&bank->chip);
                if (err) {
                        dev_err(&pdev->dev,
                                "Failed to register gpiochip %d: %d\n",
                                i, err);
                        goto err_gpiochip;
                }
        }

        return 0;

err_gpiochip:
        for (i = i - 1; i >= 0; i--) {
                struct nct5104d_gpio_bank *bank = &data->bank[i];

#if LINUX_VERSION_CODE < KERNEL_VERSION(3,18,0)
                int rm_err = gpiochip_remove(&bank->chip);
                if (rm_err < 0)
                        dev_err(&pdev->dev,
                                "Failed to remove gpiochip %d: %d\n",
                                i, rm_err);
#else /* LINUX_VERSION_CODE < KERNEL_VERSION(3,18,0) */
                gpiochip_remove (&bank->chip);
#endif /* LINUX_VERSION_CODE < KERNEL_VERSION(3,18,0) */
        }

        return err;
}

static int nct5104d_gpio_remove(struct platform_device *pdev)
{
        int i;
        struct nct5104d_gpio_data *data = platform_get_drvdata(pdev);

        for (i = 0; i < data->nr_bank; i++) {
                struct nct5104d_gpio_bank *bank = &data->bank[i];

#if LINUX_VERSION_CODE < KERNEL_VERSION(3,18,0)
                int err = gpiochip_remove(&bank->chip);
                if (err) {
                        dev_err(&pdev->dev,
                                "Failed to remove GPIO gpiochip %d: %d\n",
                                i, err);
                        return err;
                }
#else /* LINUX_VERSION_CODE < KERNEL_VERSION(3,18,0) */
                gpiochip_remove (&bank->chip);
#endif /* LINUX_VERSION_CODE < KERNEL_VERSION(3,18,0) */
        }

        return 0;
}

static int __init nct5104d_find(int addr, struct nct5104d_sio *sio)
{
        int err;
        u16 devid;
        u8 gpio_cfg;

        err = superio_enter(addr);
        if (err)
                return err;

        err = -ENODEV;

        devid = superio_inw(addr, SIO_CHIPID);
        switch (devid) {
        case SIO_NCT5104D_ID:
        case SIO_PCENGINES_APU_NCT5104D_ID1:
        case SIO_PCENGINES_APU_NCT5104D_ID2:
                sio->type = nct5104d;
                /* enable GPIO0 and GPIO1 */
                superio_select(addr, SIO_LD_GPIO);
                gpio_cfg = superio_inb(addr, SIO_GPIO_ENABLE);
                gpio_cfg |= 0x03;
                superio_outb(addr, SIO_GPIO_ENABLE, gpio_cfg);
                break;
        default:
                pr_info(DRVNAME ": Unsupported device 0x%04x\n", devid);
                goto err;
        }
        sio->addr = addr;
        err = 0;

        pr_info(DRVNAME ": Found %s at %#x chip id 0x%04x\n",
                nct5104d_names[sio->type],
                (unsigned int) addr,
                (int) superio_inw(addr, SIO_CHIPID));

        superio_select(sio->addr, SIO_LD_GPIO_MODE);
        superio_outb(sio->addr, SIO_GPIO1_MODE, 0x0);
        superio_outb(sio->addr, SIO_GPIO2_MODE, 0x0);

err:
        superio_exit(addr);
        return err;
}

static struct platform_device *nct5104d_gpio_pdev;

static int __init
nct5104d_gpio_device_add(const struct nct5104d_sio *sio)
{
        int err;

        nct5104d_gpio_pdev = platform_device_alloc(DRVNAME, -1);
        if (!nct5104d_gpio_pdev)
                pr_err(DRVNAME ": Error platform_device_alloc\n");
        if (!nct5104d_gpio_pdev)
                return -ENOMEM;

        err = platform_device_add_data(nct5104d_gpio_pdev,
                                       sio, sizeof(*sio));
        if (err) {
                pr_err(DRVNAME "Platform data allocation failed\n");
                goto err;
        }

        err = platform_device_add(nct5104d_gpio_pdev);
        if (err) {
                pr_err(DRVNAME "Device addition failed\n");
                goto err;
        }
        pr_info(DRVNAME ": Device added\n");
        return 0;

err:
        platform_device_put(nct5104d_gpio_pdev);

        return err;
}

/*
 */

static struct platform_driver nct5104d_gpio_driver = {
        .driver = {
                .owner  = THIS_MODULE,
                .name   = DRVNAME,
        },
        .probe          = nct5104d_gpio_probe,
        .remove         = nct5104d_gpio_remove,
};

static int __init nct5104d_gpio_init(void)
{
        int err;
        struct nct5104d_sio sio;
        const char *board_vendor = dmi_get_system_info(DMI_BOARD_VENDOR);
        const char *board_name = dmi_get_system_info(DMI_BOARD_NAME);

        if (nct5104d_find(0x2e, &sio) &&
            nct5104d_find(0x4e, &sio))
                return -ENODEV;

        err = platform_driver_register(&nct5104d_gpio_driver);
        if (!err) {
                pr_info(DRVNAME ": platform_driver_register\n");
                err = nct5104d_gpio_device_add(&sio);
                if (err)
                        platform_driver_unregister(&nct5104d_gpio_driver);
        }

        return err;
}
subsys_initcall(nct5104d_gpio_init);

static void __exit nct5104d_gpio_exit(void)
{
        platform_device_unregister(nct5104d_gpio_pdev);
        platform_driver_unregister(&nct5104d_gpio_driver);
}
module_exit(nct5104d_gpio_exit);

MODULE_DESCRIPTION("GPIO driver for Super-I/O chips NCT5104D");
MODULE_AUTHOR("Tasanakorn Phaipool <tasanakorn@gmail.com>");
MODULE_LICENSE("GPL");