/*
 * (C) Copyright 2009-2010
 * Nokia Siemens Networks, michael.lawnick.ext@nsn.com
 *
 * Portions Copyright (C) 2010 - 2016 Cavium, Inc.
 *
 * This is a driver for the i2c adapter in Cavium Networks' OCTEON processors.
 *
 * This file is licensed under the terms of the GNU General Public
 * License version 2. This program is licensed "as is" without any
 * warranty of any kind, whether express or implied.
 */

#include <linux/atomic.h>
#include <linux/delay.h>
#include <linux/i2c.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/sched.h>
#include <linux/slab.h>

#include <asm/octeon/octeon.h>
#include "i2c-octeon-core.h"

#define DRV_NAME "i2c-octeon"

/**
 * octeon_i2c_int_enable - enable the CORE interrupt
 * @i2c: The struct octeon_i2c
 *
 * The interrupt will be asserted when there is non-STAT_IDLE state in
 * the SW_TWSI_EOP_TWSI_STAT register.
 */
static void octeon_i2c_int_enable(struct octeon_i2c *i2c)
{
        octeon_i2c_write_int(i2c, TWSI_INT_CORE_EN);
}

/* disable the CORE interrupt */
static void octeon_i2c_int_disable(struct octeon_i2c *i2c)
{
        /* clear TS/ST/IFLG events */
        octeon_i2c_write_int(i2c, 0);
}

/**
 * octeon_i2c_int_enable78 - enable the CORE interrupt
 * @i2c: The struct octeon_i2c
 *
 * The interrupt will be asserted when there is non-STAT_IDLE state in the
 * SW_TWSI_EOP_TWSI_STAT register.
 */
static void octeon_i2c_int_enable78(struct octeon_i2c *i2c)
{
        atomic_inc_return(&i2c->int_enable_cnt);
        enable_irq(i2c->irq);
}

static void __octeon_i2c_irq_disable(atomic_t *cnt, int irq)
{
        int count;

        /*
         * The interrupt can be disabled in two places, but we only
         * want to make the disable_irq_nosync() call once, so keep
         * track with the atomic variable.
         */
        count = atomic_dec_if_positive(cnt);
        if (count >= 0)
                disable_irq_nosync(irq);
}

/* disable the CORE interrupt */
static void octeon_i2c_int_disable78(struct octeon_i2c *i2c)
{
        __octeon_i2c_irq_disable(&i2c->int_enable_cnt, i2c->irq);
}

/**
 * octeon_i2c_hlc_int_enable78 - enable the ST interrupt
 * @i2c: The struct octeon_i2c
 *
 * The interrupt will be asserted when there is non-STAT_IDLE state in
 * the SW_TWSI_EOP_TWSI_STAT register.
 */
static void octeon_i2c_hlc_int_enable78(struct octeon_i2c *i2c)
{
        atomic_inc_return(&i2c->hlc_int_enable_cnt);
        enable_irq(i2c->hlc_irq);
}

/* disable the ST interrupt */
static void octeon_i2c_hlc_int_disable78(struct octeon_i2c *i2c)
{
        __octeon_i2c_irq_disable(&i2c->hlc_int_enable_cnt, i2c->hlc_irq);
}

/* HLC interrupt service routine */
static irqreturn_t octeon_i2c_hlc_isr78(int irq, void *dev_id)
{
        struct octeon_i2c *i2c = dev_id;

        i2c->hlc_int_disable(i2c);
        wake_up(&i2c->queue);

        return IRQ_HANDLED;
}

static void octeon_i2c_hlc_int_enable(struct octeon_i2c *i2c)
{
        octeon_i2c_write_int(i2c, TWSI_INT_ST_EN);
}

static u32 octeon_i2c_functionality(struct i2c_adapter *adap)
{
        return I2C_FUNC_I2C | (I2C_FUNC_SMBUS_EMUL & ~I2C_FUNC_SMBUS_QUICK) |
               I2C_FUNC_SMBUS_READ_BLOCK_DATA | I2C_SMBUS_BLOCK_PROC_CALL;
}

static const struct i2c_algorithm octeon_i2c_algo = {
        .master_xfer = octeon_i2c_xfer,
        .functionality = octeon_i2c_functionality,
};

static const struct i2c_adapter octeon_i2c_ops = {
        .owner = THIS_MODULE,
        .name = "OCTEON adapter",
        .algo = &octeon_i2c_algo,
};

static int octeon_i2c_probe(struct platform_device *pdev)
{
        struct device_node *node = pdev->dev.of_node;
        int irq, result = 0, hlc_irq = 0;
        struct octeon_i2c *i2c;
        bool cn78xx_style;

        cn78xx_style = of_device_is_compatible(node, "cavium,octeon-7890-twsi");
        if (cn78xx_style) {
                hlc_irq = platform_get_irq(pdev, 0);
                if (hlc_irq < 0)
                        return hlc_irq;

                irq = platform_get_irq(pdev, 2);
                if (irq < 0)
                        return irq;
        } else {
                /* All adaptors have an irq.  */
                irq = platform_get_irq(pdev, 0);
                if (irq < 0)
                        return irq;
        }

        i2c = devm_kzalloc(&pdev->dev, sizeof(*i2c), GFP_KERNEL);
        if (!i2c) {
                result = -ENOMEM;
                goto out;
        }
        i2c->dev = &pdev->dev;

        i2c->roff.sw_twsi = 0x00;
        i2c->roff.twsi_int = 0x10;
        i2c->roff.sw_twsi_ext = 0x18;

        i2c->twsi_base = devm_platform_ioremap_resource(pdev, 0);
        if (IS_ERR(i2c->twsi_base)) {
                result = PTR_ERR(i2c->twsi_base);
                goto out;
        }

        /*
         * "clock-rate" is a legacy binding, the official binding is
         * "clock-frequency".  Try the official one first and then
         * fall back if it doesn't exist.
         */
        if (of_property_read_u32(node, "clock-frequency", &i2c->twsi_freq) &&
            of_property_read_u32(node, "clock-rate", &i2c->twsi_freq)) {
                dev_err(i2c->dev,
                        "no I2C 'clock-rate' or 'clock-frequency' property\n");
                result = -ENXIO;
                goto out;
        }

        i2c->sys_freq = octeon_get_io_clock_rate();

        init_waitqueue_head(&i2c->queue);

        i2c->irq = irq;

        if (cn78xx_style) {
                i2c->hlc_irq = hlc_irq;

                i2c->int_enable = octeon_i2c_int_enable78;
                i2c->int_disable = octeon_i2c_int_disable78;
                i2c->hlc_int_enable = octeon_i2c_hlc_int_enable78;
                i2c->hlc_int_disable = octeon_i2c_hlc_int_disable78;

                irq_set_status_flags(i2c->irq, IRQ_NOAUTOEN);
                irq_set_status_flags(i2c->hlc_irq, IRQ_NOAUTOEN);

                result = devm_request_irq(&pdev->dev, i2c->hlc_irq,
                                          octeon_i2c_hlc_isr78, 0,
                                          DRV_NAME, i2c);
                if (result < 0) {
                        dev_err(i2c->dev, "failed to attach interrupt\n");
                        goto out;
                }
        } else {
                i2c->int_enable = octeon_i2c_int_enable;
                i2c->int_disable = octeon_i2c_int_disable;
                i2c->hlc_int_enable = octeon_i2c_hlc_int_enable;
                i2c->hlc_int_disable = octeon_i2c_int_disable;
        }

        result = devm_request_irq(&pdev->dev, i2c->irq,
                                  octeon_i2c_isr, 0, DRV_NAME, i2c);
        if (result < 0) {
                dev_err(i2c->dev, "failed to attach interrupt\n");
                goto out;
        }

        if (OCTEON_IS_MODEL(OCTEON_CN38XX))
                i2c->broken_irq_check = true;

        result = octeon_i2c_init_lowlevel(i2c);
        if (result) {
                dev_err(i2c->dev, "init low level failed\n");
                goto  out;
        }

        octeon_i2c_set_clock(i2c);

        i2c->adap = octeon_i2c_ops;
        i2c->adap.timeout = msecs_to_jiffies(2);
        i2c->adap.retries = 5;
        i2c->adap.bus_recovery_info = &octeon_i2c_recovery_info;
        i2c->adap.dev.parent = &pdev->dev;
        i2c->adap.dev.of_node = node;
        i2c_set_adapdata(&i2c->adap, i2c);
        platform_set_drvdata(pdev, i2c);

        result = i2c_add_adapter(&i2c->adap);
        if (result < 0)
                goto out;
        dev_info(i2c->dev, "probed\n");
        return 0;

out:
        return result;
};

static int octeon_i2c_remove(struct platform_device *pdev)
{
        struct octeon_i2c *i2c = platform_get_drvdata(pdev);

        i2c_del_adapter(&i2c->adap);
        return 0;
};

static const struct of_device_id octeon_i2c_match[] = {
        { .compatible = "cavium,octeon-3860-twsi", },
        { .compatible = "cavium,octeon-7890-twsi", },
        {},
};
MODULE_DEVICE_TABLE(of, octeon_i2c_match);

static struct platform_driver octeon_i2c_driver = {
        .probe          = octeon_i2c_probe,
        .remove         = octeon_i2c_remove,
        .driver         = {
                .name   = DRV_NAME,
                .of_match_table = octeon_i2c_match,
        },
};

module_platform_driver(octeon_i2c_driver);

MODULE_AUTHOR("Michael Lawnick <michael.lawnick.ext@nsn.com>");
MODULE_DESCRIPTION("I2C-Bus adapter for Cavium OCTEON processors");
MODULE_LICENSE("GPL");