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/*
 *  A low-level PATA driver to handle a Compact Flash connected on the
 *  Mikrotik's RouterBoard 153 board.
 *
 *  Copyright (C) 2007-2008 Gabor Juhos <juhosg@openwrt.org>
 *
 *  This file was based on: drivers/ata/pata_ixp4xx_cf.c
 *      Copyright (C) 2006-07 Tower Technologies
 *      Author: Alessandro Zummo <a.zummo@towertech.it>
 *
 *  Also was based on the driver for Linux 2.4.xx published by Mikrotik for
 *  their RouterBoard 1xx and 5xx series devices. The original Mikrotik code
 *  seems not to have a license.
 *
 *  This program is free software; you can redistribute it and/or modify it
 *  under the terms of the GNU General Public License version 2 as published
 *  by the Free Software Foundation.
 *
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/io.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/gpio.h>
#include <linux/platform_device.h>

#include <linux/libata.h>
#include <scsi/scsi_host.h>

#define DRV_NAME        "pata-rb153-cf"
#define DRV_VERSION     "0.5.0"
#define DRV_DESC        "PATA driver for RouterBOARD 153 Compact Flash"

#define RB153_CF_MAXPORTS       1
#define RB153_CF_IO_DELAY       100

#define RB153_CF_REG_CMD        0x0800
#define RB153_CF_REG_CTRL       0x080E
#define RB153_CF_REG_DATA       0x0C00

struct rb153_cf_info {
        void __iomem    *iobase;
        unsigned int    gpio_line;
        int             frozen;
        unsigned int    irq;
};

static inline void rb153_pata_finish_io(struct ata_port *ap)
{
        struct rb153_cf_info *info = ap->host->private_data;

        /* FIXME: Keep previous delay. If this is merely a fence then
         * ata_sff_sync might be sufficient. */
        ata_sff_dma_pause(ap);
        ndelay(RB153_CF_IO_DELAY);

        irq_set_irq_type(info->irq, IRQ_TYPE_LEVEL_HIGH);
}

static void rb153_pata_exec_command(struct ata_port *ap,
                                        const struct ata_taskfile *tf)
{
        writeb(tf->command, ap->ioaddr.command_addr);
        rb153_pata_finish_io(ap);
}

static unsigned int rb153_pata_data_xfer(struct ata_device *adev,
                                        unsigned char *buf,
                                        unsigned int buflen,
                                        int write_data)
{
        void __iomem *ioaddr = adev->link->ap->ioaddr.data_addr;
        unsigned int t;

        t = buflen;
        if (write_data) {
                for (; t > 0; t--, buf++)
                        writeb(*buf, ioaddr);
        } else {
                for (; t > 0; t--, buf++)
                        *buf = readb(ioaddr);
        }

        rb153_pata_finish_io(adev->link->ap);
        return buflen;
}

static void rb153_pata_freeze(struct ata_port *ap)
{
        struct rb153_cf_info *info = ap->host->private_data;

        info->frozen = 1;
}

static void rb153_pata_thaw(struct ata_port *ap)
{
        struct rb153_cf_info *info = ap->host->private_data;

        info->frozen = 0;
}

static irqreturn_t rb153_pata_irq_handler(int irq, void *dev_instance)
{
        struct ata_host *ah = dev_instance;
        struct rb153_cf_info *info = ah->private_data;

        if (gpio_get_value(info->gpio_line)) {
                irq_set_irq_type(info->irq, IRQ_TYPE_LEVEL_LOW);
                if (!info->frozen)
                        ata_sff_interrupt(irq, dev_instance);
        } else {
                irq_set_irq_type(info->irq, IRQ_TYPE_LEVEL_HIGH);
        }

        return IRQ_HANDLED;
}

static struct ata_port_operations rb153_pata_port_ops = {
        .inherits               = &ata_sff_port_ops,
        .sff_exec_command       = rb153_pata_exec_command,
        .sff_data_xfer          = rb153_pata_data_xfer,
        .freeze                 = rb153_pata_freeze,
        .thaw                   = rb153_pata_thaw,
};

static struct scsi_host_template rb153_pata_sht = {
        ATA_PIO_SHT(DRV_NAME),
};

static void rb153_pata_setup_port(struct ata_host *ah)
{
        struct rb153_cf_info *info = ah->private_data;
        struct ata_port *ap;

        ap = ah->ports[0];

        ap->ops         = &rb153_pata_port_ops;
        ap->pio_mask    = 0x1f; /* PIO4 */

        ap->ioaddr.cmd_addr     = info->iobase + RB153_CF_REG_CMD;
        ap->ioaddr.ctl_addr     = info->iobase + RB153_CF_REG_CTRL;
        ap->ioaddr.altstatus_addr = info->iobase + RB153_CF_REG_CTRL;

        ata_sff_std_ports(&ap->ioaddr);

        ap->ioaddr.data_addr = info->iobase + RB153_CF_REG_DATA;
}

static int rb153_pata_driver_probe(struct platform_device *pdev)
{
        unsigned int irq;
        int gpio;
        struct resource *res;
        struct ata_host *ah;
        struct rb153_cf_info *info;
        int ret;

        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        if (!res) {
                dev_err(&pdev->dev, "no IOMEM resource found\n");
                return -EINVAL;
        }

        irq = platform_get_irq(pdev, 0);
        if (irq <= 0) {
                dev_err(&pdev->dev, "no IRQ resource found\n");
                return -ENOENT;
        }

        gpio = irq_to_gpio(irq);
        if (gpio < 0) {
                dev_err(&pdev->dev, "no GPIO found for irq%d\n", irq);
                return -ENOENT;
        }

        ret = gpio_request(gpio, DRV_NAME);
        if (ret) {
                dev_err(&pdev->dev, "GPIO request failed\n");
                return ret;
        }

        ah = ata_host_alloc(&pdev->dev, RB153_CF_MAXPORTS);
        if (!ah)
                return -ENOMEM;

        platform_set_drvdata(pdev, ah);

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

        ah->private_data = info;
        info->gpio_line = gpio;
        info->irq = irq;

        info->iobase = devm_ioremap_nocache(&pdev->dev, res->start,
                                res->end - res->start + 1);
        if (!info->iobase)
                return -ENOMEM;

        ret = gpio_direction_input(gpio);
        if (ret) {
                dev_err(&pdev->dev, "unable to set GPIO direction, err=%d\n",
                                ret);
                goto err_free_gpio;
        }

        rb153_pata_setup_port(ah);

        ret = ata_host_activate(ah, irq, rb153_pata_irq_handler,
                                IRQF_TRIGGER_LOW, &rb153_pata_sht);
        if (ret)
                goto err_free_gpio;

        return 0;

err_free_gpio:
        gpio_free(gpio);

        return ret;
}

static int rb153_pata_driver_remove(struct platform_device *pdev)
{
        struct ata_host *ah = platform_get_drvdata(pdev);
        struct rb153_cf_info *info = ah->private_data;

        ata_host_detach(ah);
        gpio_free(info->gpio_line);

        return 0;
}

static struct platform_driver rb153_pata_platform_driver = {
        .probe          = rb153_pata_driver_probe,
        .remove         = rb153_pata_driver_remove,
        .driver  = {
                .name   = DRV_NAME,
                .owner  = THIS_MODULE,
        },
};

/* ------------------------------------------------------------------------ */

#define DRV_INFO DRV_DESC " version " DRV_VERSION

static int __init rb153_pata_module_init(void)
{
        printk(KERN_INFO DRV_INFO "\n");

        return platform_driver_register(&rb153_pata_platform_driver);
}

static void __exit rb153_pata_module_exit(void)
{
        platform_driver_unregister(&rb153_pata_platform_driver);
}

MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org>");
MODULE_DESCRIPTION(DRV_DESC);
MODULE_VERSION(DRV_VERSION);
MODULE_LICENSE("GPL v2");

module_init(rb153_pata_module_init);
module_exit(rb153_pata_module_exit);