/*
 * Intel ICH6-10, Series 5 and 6 GPIO driver
 *
 * Copyright (C) 2010 Extreme Engineering Solutions.
 *
 * 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.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/pci.h>
#include <linux/gpio.h>
#include <linux/platform_device.h>
#include <linux/mfd/lpc_ich.h>

#define DRV_NAME "gpio_ich"

/*
 * GPIO register offsets in GPIO I/O space.
 * Each chunk of 32 GPIOs is manipulated via its own USE_SELx, IO_SELx, and
 * LVLx registers.  Logic in the read/write functions takes a register and
 * an absolute bit number and determines the proper register offset and bit
 * number in that register.  For example, to read the value of GPIO bit 50
 * the code would access offset ichx_regs[2(=GPIO_LVL)][1(=50/32)],
 * bit 18 (50%32).
 */
enum GPIO_REG {
        GPIO_USE_SEL = 0,
        GPIO_IO_SEL,
        GPIO_LVL,
};

static const u8 ichx_regs[3][3] = {
        {0x00, 0x30, 0x40},     /* USE_SEL[1-3] offsets */
        {0x04, 0x34, 0x44},     /* IO_SEL[1-3] offsets */
        {0x0c, 0x38, 0x48},     /* LVL[1-3] offsets */
};

static const u8 ichx_reglen[3] = {
        0x30, 0x10, 0x10,
};

#define ICHX_WRITE(val, reg, base_res)  outl(val, (reg) + (base_res)->start)
#define ICHX_READ(reg, base_res)        inl((reg) + (base_res)->start)

struct ichx_desc {
        /* Max GPIO pins the chipset can have */
        uint ngpio;

        /* Whether the chipset has GPIO in GPE0_STS in the PM IO region */
        bool uses_gpe0;

        /* USE_SEL is bogus on some chipsets, eg 3100 */
        u32 use_sel_ignore[3];

        /* Some chipsets have quirks, let these use their own request/get */
        int (*request)(struct gpio_chip *chip, unsigned offset);
        int (*get)(struct gpio_chip *chip, unsigned offset);
};

static struct {
        spinlock_t lock;
        struct platform_device *dev;
        struct gpio_chip chip;
        struct resource *gpio_base;     /* GPIO IO base */
        struct resource *pm_base;       /* Power Mangagment IO base */
        struct ichx_desc *desc; /* Pointer to chipset-specific description */
        u32 orig_gpio_ctrl;     /* Orig CTRL value, used to restore on exit */
        u8 use_gpio;            /* Which GPIO groups are usable */
} ichx_priv;

static int modparam_gpiobase = -1;      /* dynamic */
module_param_named(gpiobase, modparam_gpiobase, int, 0444);
MODULE_PARM_DESC(gpiobase, "The GPIO number base. -1 means dynamic, "
                           "which is the default.");

static int ichx_write_bit(int reg, unsigned nr, int val, int verify)
{
        unsigned long flags;
        u32 data, tmp;
        int reg_nr = nr / 32;
        int bit = nr & 0x1f;
        int ret = 0;

        spin_lock_irqsave(&ichx_priv.lock, flags);

        data = ICHX_READ(ichx_regs[reg][reg_nr], ichx_priv.gpio_base);
        if (val)
                data |= 1 << bit;
        else
                data &= ~(1 << bit);
        ICHX_WRITE(data, ichx_regs[reg][reg_nr], ichx_priv.gpio_base);
        tmp = ICHX_READ(ichx_regs[reg][reg_nr], ichx_priv.gpio_base);
        if (verify && data != tmp)
                ret = -EPERM;

        spin_unlock_irqrestore(&ichx_priv.lock, flags);

        return ret;
}

static int ichx_read_bit(int reg, unsigned nr)
{
        unsigned long flags;
        u32 data;
        int reg_nr = nr / 32;
        int bit = nr & 0x1f;

        spin_lock_irqsave(&ichx_priv.lock, flags);

        data = ICHX_READ(ichx_regs[reg][reg_nr], ichx_priv.gpio_base);

        spin_unlock_irqrestore(&ichx_priv.lock, flags);

        return data & (1 << bit) ? 1 : 0;
}

static int ichx_gpio_check_available(struct gpio_chip *gpio, unsigned nr)
{
        return (ichx_priv.use_gpio & (1 << (nr / 32))) ? 0 : -ENXIO;
}

static int ichx_gpio_direction_input(struct gpio_chip *gpio, unsigned nr)
{
        if (!ichx_gpio_check_available(gpio, nr))
                return -ENXIO;

        /*
         * Try setting pin as an input and verify it worked since many pins
         * are output-only.
         */
        if (ichx_write_bit(GPIO_IO_SEL, nr, 1, 1))
                return -EINVAL;

        return 0;
}

static int ichx_gpio_direction_output(struct gpio_chip *gpio, unsigned nr,
                                        int val)
{
        if (!ichx_gpio_check_available(gpio, nr))
                return -ENXIO;

        /* Set GPIO output value. */
        ichx_write_bit(GPIO_LVL, nr, val, 0);

        /*
         * Try setting pin as an output and verify it worked since many pins
         * are input-only.
         */
        if (ichx_write_bit(GPIO_IO_SEL, nr, 0, 1))
                return -EINVAL;

        return 0;
}

static int ichx_gpio_get(struct gpio_chip *chip, unsigned nr)
{
        if (!ichx_gpio_check_available(chip, nr))
                return -ENXIO;

        return ichx_read_bit(GPIO_LVL, nr);
}

static int ich6_gpio_get(struct gpio_chip *chip, unsigned nr)
{
        unsigned long flags;
        u32 data;

        if (!ichx_gpio_check_available(chip, nr))
                return -ENXIO;

        /*
         * GPI 0 - 15 need to be read from the power management registers on
         * a ICH6/3100 bridge.
         */
        if (nr < 16) {
                if (!ichx_priv.pm_base)
                        return -ENXIO;

                spin_lock_irqsave(&ichx_priv.lock, flags);

                /* GPI 0 - 15 are latched, write 1 to clear*/
                ICHX_WRITE(1 << (16 + nr), 0, ichx_priv.pm_base);
                data = ICHX_READ(0, ichx_priv.pm_base);

                spin_unlock_irqrestore(&ichx_priv.lock, flags);

                return (data >> 16) & (1 << nr) ? 1 : 0;
        } else {
                return ichx_gpio_get(chip, nr);
        }
}

static int ichx_gpio_request(struct gpio_chip *chip, unsigned nr)
{
        /*
         * Note we assume the BIOS properly set a bridge's USE value.  Some
         * chips (eg Intel 3100) have bogus USE values though, so first see if
         * the chipset's USE value can be trusted for this specific bit.
         * If it can't be trusted, assume that the pin can be used as a GPIO.
         */
        if (ichx_priv.desc->use_sel_ignore[nr / 32] & (1 << (nr & 0x1f)))
                return 1;

        return ichx_read_bit(GPIO_USE_SEL, nr) ? 0 : -ENODEV;
}

static int ich6_gpio_request(struct gpio_chip *chip, unsigned nr)
{
        /*
         * Fixups for bits 16 and 17 are necessary on the Intel ICH6/3100
         * bridge as they are controlled by USE register bits 0 and 1.  See
         * "Table 704 GPIO_USE_SEL1 register" in the i3100 datasheet for
         * additional info.
         */
        if (nr == 16 || nr == 17)
                nr -= 16;

        return ichx_gpio_request(chip, nr);
}

static void ichx_gpio_set(struct gpio_chip *chip, unsigned nr, int val)
{
        ichx_write_bit(GPIO_LVL, nr, val, 0);
}

static void __devinit ichx_gpiolib_setup(struct gpio_chip *chip)
{
        chip->owner = THIS_MODULE;
        chip->label = DRV_NAME;
        chip->dev = &ichx_priv.dev->dev;

        /* Allow chip-specific overrides of request()/get() */
        chip->request = ichx_priv.desc->request ?
                ichx_priv.desc->request : ichx_gpio_request;
        chip->get = ichx_priv.desc->get ?
                ichx_priv.desc->get : ichx_gpio_get;

        chip->set = ichx_gpio_set;
        chip->direction_input = ichx_gpio_direction_input;
        chip->direction_output = ichx_gpio_direction_output;
        chip->base = modparam_gpiobase;
        chip->ngpio = ichx_priv.desc->ngpio;
        chip->can_sleep = 0;
        chip->dbg_show = NULL;
}

/* ICH6-based, 631xesb-based */
static struct ichx_desc ich6_desc = {
        /* Bridges using the ICH6 controller need fixups for GPIO 0 - 17 */
        .request = ich6_gpio_request,
        .get = ich6_gpio_get,

        /* GPIO 0-15 are read in the GPE0_STS PM register */
        .uses_gpe0 = true,

        .ngpio = 50,
};

/* Intel 3100 */
static struct ichx_desc i3100_desc = {
        /*
         * Bits 16,17, 20 of USE_SEL and bit 16 of USE_SEL2 always read 0 on
         * the Intel 3100.  See "Table 712. GPIO Summary Table" of 3100
         * Datasheet for more info.
         */
        .use_sel_ignore = {0x00130000, 0x00010000, 0x0},

        /* The 3100 needs fixups for GPIO 0 - 17 */
        .request = ich6_gpio_request,
        .get = ich6_gpio_get,

        /* GPIO 0-15 are read in the GPE0_STS PM register */
        .uses_gpe0 = true,

        .ngpio = 50,
};

/* ICH7 and ICH8-based */
static struct ichx_desc ich7_desc = {
        .ngpio = 50,
};

/* ICH9-based */
static struct ichx_desc ich9_desc = {
        .ngpio = 61,
};

/* ICH10-based - Consumer/corporate versions have different amount of GPIO */
static struct ichx_desc ich10_cons_desc = {
        .ngpio = 61,
};
static struct ichx_desc ich10_corp_desc = {
        .ngpio = 72,
};

/* Intel 5 series, 6 series, 3400 series, and C200 series */
static struct ichx_desc intel5_desc = {
        .ngpio = 76,
};

static int __devinit ichx_gpio_request_regions(struct resource *res_base,
                                                const char *name, u8 use_gpio)
{
        int i;

        if (!res_base || !res_base->start || !res_base->end)
                return -ENODEV;

        for (i = 0; i < ARRAY_SIZE(ichx_regs[0]); i++) {
                if (!(use_gpio & (1 << i)))
                        continue;
                if (!request_region(res_base->start + ichx_regs[0][i],
                                    ichx_reglen[i], name))
                        goto request_err;
        }
        return 0;

request_err:
        /* Clean up: release already requested regions, if any */
        for (i--; i >= 0; i--) {
                if (!(use_gpio & (1 << i)))
                        continue;
                release_region(res_base->start + ichx_regs[0][i],
                               ichx_reglen[i]);
        }
        return -EBUSY;
}

static void ichx_gpio_release_regions(struct resource *res_base, u8 use_gpio)
{
        int i;

        for (i = 0; i < ARRAY_SIZE(ichx_regs[0]); i++) {
                if (!(use_gpio & (1 << i)))
                        continue;
                release_region(res_base->start + ichx_regs[0][i],
                               ichx_reglen[i]);
        }
}

static int __devinit ichx_gpio_probe(struct platform_device *pdev)
{
        struct resource *res_base, *res_pm;
        int err;
        struct lpc_ich_info *ich_info = pdev->dev.platform_data;

        if (!ich_info)
                return -ENODEV;

        ichx_priv.dev = pdev;

        switch (ich_info->gpio_version) {
        case ICH_I3100_GPIO:
                ichx_priv.desc = &i3100_desc;
                break;
        case ICH_V5_GPIO:
                ichx_priv.desc = &intel5_desc;
                break;
        case ICH_V6_GPIO:
                ichx_priv.desc = &ich6_desc;
                break;
        case ICH_V7_GPIO:
                ichx_priv.desc = &ich7_desc;
                break;
        case ICH_V9_GPIO:
                ichx_priv.desc = &ich9_desc;
                break;
        case ICH_V10CORP_GPIO:
                ichx_priv.desc = &ich10_corp_desc;
                break;
        case ICH_V10CONS_GPIO:
                ichx_priv.desc = &ich10_cons_desc;
                break;
        default:
                return -ENODEV;
        }

        res_base = platform_get_resource(pdev, IORESOURCE_IO, ICH_RES_GPIO);
        ichx_priv.use_gpio = ich_info->use_gpio;
        err = ichx_gpio_request_regions(res_base, pdev->name,
                                        ichx_priv.use_gpio);
        if (err)
                return err;

        ichx_priv.gpio_base = res_base;

        /*
         * If necessary, determine the I/O address of ACPI/power management
         * registers which are needed to read the the GPE0 register for GPI pins
         * 0 - 15 on some chipsets.
         */
        if (!ichx_priv.desc->uses_gpe0)
                goto init;

        res_pm = platform_get_resource(pdev, IORESOURCE_IO, ICH_RES_GPE0);
        if (!res_pm) {
                pr_warn("ACPI BAR is unavailable, GPI 0 - 15 unavailable\n");
                goto init;
        }

        if (!request_region(res_pm->start, resource_size(res_pm),
                        pdev->name)) {
                pr_warn("ACPI BAR is busy, GPI 0 - 15 unavailable\n");
                goto init;
        }

        ichx_priv.pm_base = res_pm;

init:
        ichx_gpiolib_setup(&ichx_priv.chip);
        err = gpiochip_add(&ichx_priv.chip);
        if (err) {
                pr_err("Failed to register GPIOs\n");
                goto add_err;
        }

        pr_info("GPIO from %d to %d on %s\n", ichx_priv.chip.base,
               ichx_priv.chip.base + ichx_priv.chip.ngpio - 1, DRV_NAME);

        return 0;

add_err:
        ichx_gpio_release_regions(ichx_priv.gpio_base, ichx_priv.use_gpio);
        if (ichx_priv.pm_base)
                release_region(ichx_priv.pm_base->start,
                                resource_size(ichx_priv.pm_base));
        return err;
}

static int __devexit ichx_gpio_remove(struct platform_device *pdev)
{
        int err;

        err = gpiochip_remove(&ichx_priv.chip);
        if (err) {
                dev_err(&pdev->dev, "%s failed, %d\n",
                                "gpiochip_remove()", err);
                return err;
        }

        ichx_gpio_release_regions(ichx_priv.gpio_base, ichx_priv.use_gpio);
        if (ichx_priv.pm_base)
                release_region(ichx_priv.pm_base->start,
                                resource_size(ichx_priv.pm_base));

        return 0;
}

static struct platform_driver ichx_gpio_driver = {
        .driver         = {
                .owner  = THIS_MODULE,
                .name   = DRV_NAME,
        },
        .probe          = ichx_gpio_probe,
        .remove         = __devexit_p(ichx_gpio_remove),
};

module_platform_driver(ichx_gpio_driver);

MODULE_AUTHOR("Peter Tyser <ptyser@xes-inc.com>");
MODULE_DESCRIPTION("GPIO interface for Intel ICH series");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:"DRV_NAME);