/*
 * Copyright (c) 2010 Samsung Electronics Co., Ltd.
 *              http://www.samsung.com
 *
 * PATA driver for Samsung SoCs.
 * Supports CF Interface in True IDE mode. Currently only PIO mode has been
 * implemented; UDMA support has to be added.
 *
 * Based on:
 *      PATA driver for AT91SAM9260 Static Memory Controller
 *      PATA driver for Toshiba SCC controller
 *
 * 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/init.h>
#include <linux/clk.h>
#include <linux/libata.h>
#include <linux/platform_device.h>
#include <linux/slab.h>

#include <plat/ata.h>
#include <plat/regs-ata.h>

#define DRV_NAME "pata_samsung_cf"
#define DRV_VERSION "0.1"

enum s3c_cpu_type {
        TYPE_S3C64XX,
        TYPE_S5PC100,
        TYPE_S5PV210,
};

/*
 * struct s3c_ide_info - S3C PATA instance.
 * @clk: The clock resource for this controller.
 * @ide_addr: The area mapped for the hardware registers.
 * @sfr_addr: The area mapped for the special function registers.
 * @irq: The IRQ number we are using.
 * @cpu_type: The exact type of this controller.
 * @fifo_status_reg: The ATA_FIFO_STATUS register offset.
 */
struct s3c_ide_info {
        struct clk *clk;
        void __iomem *ide_addr;
        void __iomem *sfr_addr;
        unsigned int irq;
        enum s3c_cpu_type cpu_type;
        unsigned int fifo_status_reg;
};

static void pata_s3c_set_endian(void __iomem *s3c_ide_regbase, u8 mode)
{
        u32 reg = readl(s3c_ide_regbase + S3C_ATA_CFG);
        reg = mode ? (reg & ~S3C_ATA_CFG_SWAP) : (reg | S3C_ATA_CFG_SWAP);
        writel(reg, s3c_ide_regbase + S3C_ATA_CFG);
}

static void pata_s3c_cfg_mode(void __iomem *s3c_ide_sfrbase)
{
        /* Select true-ide as the internal operating mode */
        writel(readl(s3c_ide_sfrbase + S3C_CFATA_MUX) | S3C_CFATA_MUX_TRUEIDE,
                s3c_ide_sfrbase + S3C_CFATA_MUX);
}

static unsigned long
pata_s3c_setup_timing(struct s3c_ide_info *info, const struct ata_timing *ata)
{
        int t1 = ata->setup;
        int t2 = ata->act8b;
        int t2i = ata->rec8b;
        ulong piotime;

        piotime = ((t2i & 0xff) << 12) | ((t2 & 0xff) << 4) | (t1 & 0xf);

        return piotime;
}

static void pata_s3c_set_piomode(struct ata_port *ap, struct ata_device *adev)
{
        struct s3c_ide_info *info = ap->host->private_data;
        struct ata_timing timing;
        int cycle_time;
        ulong ata_cfg = readl(info->ide_addr + S3C_ATA_CFG);
        ulong piotime;

        /* Enables IORDY if mode requires it */
        if (ata_pio_need_iordy(adev))
                ata_cfg |= S3C_ATA_CFG_IORDYEN;
        else
                ata_cfg &= ~S3C_ATA_CFG_IORDYEN;

        cycle_time = (int)(1000000000UL / clk_get_rate(info->clk));

        ata_timing_compute(adev, adev->pio_mode, &timing,
                                        cycle_time * 1000, 0);

        piotime = pata_s3c_setup_timing(info, &timing);

        writel(ata_cfg, info->ide_addr + S3C_ATA_CFG);
        writel(piotime, info->ide_addr + S3C_ATA_PIO_TIME);
}

/*
 * Waits until the IDE controller is able to perform next read/write
 * operation to the disk. Needed for 64XX series boards only.
 */
static int wait_for_host_ready(struct s3c_ide_info *info)
{
        ulong timeout;
        void __iomem *fifo_reg = info->ide_addr + info->fifo_status_reg;

        /* wait for maximum of 20 msec */
        timeout = jiffies + msecs_to_jiffies(20);
        while (time_before(jiffies, timeout)) {
                if ((readl(fifo_reg) >> 28) == 0)
                        return 0;
        }
        return -EBUSY;
}

/*
 * Writes to one of the task file registers.
 */
static void ata_outb(struct ata_host *host, u8 addr, void __iomem *reg)
{
        struct s3c_ide_info *info = host->private_data;

        wait_for_host_ready(info);
        writeb(addr, reg);
}

/*
 * Reads from one of the task file registers.
 */
static u8 ata_inb(struct ata_host *host, void __iomem *reg)
{
        struct s3c_ide_info *info = host->private_data;
        u8 temp;

        wait_for_host_ready(info);
        (void) readb(reg);
        wait_for_host_ready(info);
        temp = readb(info->ide_addr + S3C_ATA_PIO_RDATA);
        return temp;
}

/*
 * pata_s3c_tf_load - send taskfile registers to host controller
 */
static void pata_s3c_tf_load(struct ata_port *ap,
                                const struct ata_taskfile *tf)
{
        struct ata_ioports *ioaddr = &ap->ioaddr;
        unsigned int is_addr = tf->flags & ATA_TFLAG_ISADDR;

        if (tf->ctl != ap->last_ctl) {
                ata_outb(ap->host, tf->ctl, ioaddr->ctl_addr);
                ap->last_ctl = tf->ctl;
                ata_wait_idle(ap);
        }

        if (is_addr && (tf->flags & ATA_TFLAG_LBA48)) {
                ata_outb(ap->host, tf->hob_feature, ioaddr->feature_addr);
                ata_outb(ap->host, tf->hob_nsect, ioaddr->nsect_addr);
                ata_outb(ap->host, tf->hob_lbal, ioaddr->lbal_addr);
                ata_outb(ap->host, tf->hob_lbam, ioaddr->lbam_addr);
                ata_outb(ap->host, tf->hob_lbah, ioaddr->lbah_addr);
        }

        if (is_addr) {
                ata_outb(ap->host, tf->feature, ioaddr->feature_addr);
                ata_outb(ap->host, tf->nsect, ioaddr->nsect_addr);
                ata_outb(ap->host, tf->lbal, ioaddr->lbal_addr);
                ata_outb(ap->host, tf->lbam, ioaddr->lbam_addr);
                ata_outb(ap->host, tf->lbah, ioaddr->lbah_addr);
        }

        if (tf->flags & ATA_TFLAG_DEVICE)
                ata_outb(ap->host, tf->device, ioaddr->device_addr);

        ata_wait_idle(ap);
}

/*
 * pata_s3c_tf_read - input device's ATA taskfile shadow registers
 */
static void pata_s3c_tf_read(struct ata_port *ap, struct ata_taskfile *tf)
{
        struct ata_ioports *ioaddr = &ap->ioaddr;

        tf->feature = ata_inb(ap->host, ioaddr->error_addr);
        tf->nsect = ata_inb(ap->host, ioaddr->nsect_addr);
        tf->lbal = ata_inb(ap->host, ioaddr->lbal_addr);
        tf->lbam = ata_inb(ap->host, ioaddr->lbam_addr);
        tf->lbah = ata_inb(ap->host, ioaddr->lbah_addr);
        tf->device = ata_inb(ap->host, ioaddr->device_addr);

        if (tf->flags & ATA_TFLAG_LBA48) {
                ata_outb(ap->host, tf->ctl | ATA_HOB, ioaddr->ctl_addr);
                tf->hob_feature = ata_inb(ap->host, ioaddr->error_addr);
                tf->hob_nsect = ata_inb(ap->host, ioaddr->nsect_addr);
                tf->hob_lbal = ata_inb(ap->host, ioaddr->lbal_addr);
                tf->hob_lbam = ata_inb(ap->host, ioaddr->lbam_addr);
                tf->hob_lbah = ata_inb(ap->host, ioaddr->lbah_addr);
                ata_outb(ap->host, tf->ctl, ioaddr->ctl_addr);
                ap->last_ctl = tf->ctl;
        }
}

/*
 * pata_s3c_exec_command - issue ATA command to host controller
 */
static void pata_s3c_exec_command(struct ata_port *ap,
                                const struct ata_taskfile *tf)
{
        ata_outb(ap->host, tf->command, ap->ioaddr.command_addr);
        ata_sff_pause(ap);
}

/*
 * pata_s3c_check_status - Read device status register
 */
static u8 pata_s3c_check_status(struct ata_port *ap)
{
        return ata_inb(ap->host, ap->ioaddr.status_addr);
}

/*
 * pata_s3c_check_altstatus - Read alternate device status register
 */
static u8 pata_s3c_check_altstatus(struct ata_port *ap)
{
        return ata_inb(ap->host, ap->ioaddr.altstatus_addr);
}

/*
 * pata_s3c_data_xfer - Transfer data by PIO
 */
unsigned int pata_s3c_data_xfer(struct ata_device *dev, unsigned char *buf,
                                unsigned int buflen, int rw)
{
        struct ata_port *ap = dev->link->ap;
        struct s3c_ide_info *info = ap->host->private_data;
        void __iomem *data_addr = ap->ioaddr.data_addr;
        unsigned int words = buflen >> 1, i;
        u16 *data_ptr = (u16 *)buf;

        /* Requires wait same as in ata_inb/ata_outb */
        if (rw == READ)
                for (i = 0; i < words; i++, data_ptr++) {
                        wait_for_host_ready(info);
                        (void) readw(data_addr);
                        wait_for_host_ready(info);
                        *data_ptr = readw(info->ide_addr
                                        + S3C_ATA_PIO_RDATA);
                }
        else
                for (i = 0; i < words; i++, data_ptr++) {
                        wait_for_host_ready(info);
                        writew(*data_ptr, data_addr);
                }

        if (buflen & 0x01)
                dev_err(ap->dev, "unexpected trailing data\n");

        return words << 1;
}

/*
 * pata_s3c_dev_select - Select device on ATA bus
 */
static void pata_s3c_dev_select(struct ata_port *ap, unsigned int device)
{
        u8 tmp = ATA_DEVICE_OBS;

        if (device != 0)
                tmp |= ATA_DEV1;

        ata_outb(ap->host, tmp, ap->ioaddr.device_addr);
        ata_sff_pause(ap);
}

/*
 * pata_s3c_devchk - PATA device presence detection
 */
static unsigned int pata_s3c_devchk(struct ata_port *ap,
                                unsigned int device)
{
        struct ata_ioports *ioaddr = &ap->ioaddr;
        u8 nsect, lbal;

        pata_s3c_dev_select(ap, device);

        ata_outb(ap->host, 0x55, ioaddr->nsect_addr);
        ata_outb(ap->host, 0xaa, ioaddr->lbal_addr);

        ata_outb(ap->host, 0xaa, ioaddr->nsect_addr);
        ata_outb(ap->host, 0x55, ioaddr->lbal_addr);

        ata_outb(ap->host, 0x55, ioaddr->nsect_addr);
        ata_outb(ap->host, 0xaa, ioaddr->lbal_addr);

        nsect = ata_inb(ap->host, ioaddr->nsect_addr);
        lbal = ata_inb(ap->host, ioaddr->lbal_addr);

        if ((nsect == 0x55) && (lbal == 0xaa))
                return 1;       /* we found a device */

        return 0;               /* nothing found */
}

/*
 * pata_s3c_wait_after_reset - wait for devices to become ready after reset
 */
static int pata_s3c_wait_after_reset(struct ata_link *link,
                unsigned long deadline)
{
        int rc;

        ata_msleep(link->ap, ATA_WAIT_AFTER_RESET);

        /* always check readiness of the master device */
        rc = ata_sff_wait_ready(link, deadline);
        /* -ENODEV means the odd clown forgot the D7 pulldown resistor
         * and TF status is 0xff, bail out on it too.
         */
        if (rc)
                return rc;

        return 0;
}

/*
 * pata_s3c_bus_softreset - PATA device software reset
 */
static unsigned int pata_s3c_bus_softreset(struct ata_port *ap,
                unsigned long deadline)
{
        struct ata_ioports *ioaddr = &ap->ioaddr;

        /* software reset.  causes dev0 to be selected */
        ata_outb(ap->host, ap->ctl, ioaddr->ctl_addr);
        udelay(20);
        ata_outb(ap->host, ap->ctl | ATA_SRST, ioaddr->ctl_addr);
        udelay(20);
        ata_outb(ap->host, ap->ctl, ioaddr->ctl_addr);
        ap->last_ctl = ap->ctl;

        return pata_s3c_wait_after_reset(&ap->link, deadline);
}

/*
 * pata_s3c_softreset - reset host port via ATA SRST
 */
static int pata_s3c_softreset(struct ata_link *link, unsigned int *classes,
                         unsigned long deadline)
{
        struct ata_port *ap = link->ap;
        unsigned int devmask = 0;
        int rc;
        u8 err;

        /* determine if device 0 is present */
        if (pata_s3c_devchk(ap, 0))
                devmask |= (1 << 0);

        /* select device 0 again */
        pata_s3c_dev_select(ap, 0);

        /* issue bus reset */
        rc = pata_s3c_bus_softreset(ap, deadline);
        /* if link is occupied, -ENODEV too is an error */
        if (rc && rc != -ENODEV) {
                ata_link_printk(link, KERN_ERR, "SRST failed (errno=%d)\n", rc);
                return rc;
        }

        /* determine by signature whether we have ATA or ATAPI devices */
        classes[0] = ata_sff_dev_classify(&ap->link.device[0],
                                          devmask & (1 << 0), &err);

        return 0;
}

/*
 * pata_s3c_set_devctl - Write device control register
 */
static void pata_s3c_set_devctl(struct ata_port *ap, u8 ctl)
{
        ata_outb(ap->host, ctl, ap->ioaddr.ctl_addr);
}

static struct scsi_host_template pata_s3c_sht = {
        ATA_PIO_SHT(DRV_NAME),
};

static struct ata_port_operations pata_s3c_port_ops = {
        .inherits               = &ata_sff_port_ops,
        .sff_check_status       = pata_s3c_check_status,
        .sff_check_altstatus    = pata_s3c_check_altstatus,
        .sff_tf_load            = pata_s3c_tf_load,
        .sff_tf_read            = pata_s3c_tf_read,
        .sff_data_xfer          = pata_s3c_data_xfer,
        .sff_exec_command       = pata_s3c_exec_command,
        .sff_dev_select         = pata_s3c_dev_select,
        .sff_set_devctl         = pata_s3c_set_devctl,
        .softreset              = pata_s3c_softreset,
        .set_piomode            = pata_s3c_set_piomode,
};

static struct ata_port_operations pata_s5p_port_ops = {
        .inherits               = &ata_sff_port_ops,
        .set_piomode            = pata_s3c_set_piomode,
};

static void pata_s3c_enable(void *s3c_ide_regbase, bool state)
{
        u32 temp = readl(s3c_ide_regbase + S3C_ATA_CTRL);
        temp = state ? (temp | 1) : (temp & ~1);
        writel(temp, s3c_ide_regbase + S3C_ATA_CTRL);
}

static irqreturn_t pata_s3c_irq(int irq, void *dev_instance)
{
        struct ata_host *host = dev_instance;
        struct s3c_ide_info *info = host->private_data;
        u32 reg;

        reg = readl(info->ide_addr + S3C_ATA_IRQ);
        writel(reg, info->ide_addr + S3C_ATA_IRQ);

        return ata_sff_interrupt(irq, dev_instance);
}

static void pata_s3c_hwinit(struct s3c_ide_info *info,
                                struct s3c_ide_platdata *pdata)
{
        switch (info->cpu_type) {
        case TYPE_S3C64XX:
                /* Configure as big endian */
                pata_s3c_cfg_mode(info->sfr_addr);
                pata_s3c_set_endian(info->ide_addr, 1);
                pata_s3c_enable(info->ide_addr, true);
                msleep(100);

                /* Remove IRQ Status */
                writel(0x1f, info->ide_addr + S3C_ATA_IRQ);
                writel(0x1b, info->ide_addr + S3C_ATA_IRQ_MSK);
                break;

        case TYPE_S5PC100:
                pata_s3c_cfg_mode(info->sfr_addr);
                /* FALLTHROUGH */

        case TYPE_S5PV210:
                /* Configure as little endian */
                pata_s3c_set_endian(info->ide_addr, 0);
                pata_s3c_enable(info->ide_addr, true);
                msleep(100);

                /* Remove IRQ Status */
                writel(0x3f, info->ide_addr + S3C_ATA_IRQ);
                writel(0x3f, info->ide_addr + S3C_ATA_IRQ_MSK);
                break;

        default:
                BUG();
        }
}

static int __init pata_s3c_probe(struct platform_device *pdev)
{
        struct s3c_ide_platdata *pdata = pdev->dev.platform_data;
        struct device *dev = &pdev->dev;
        struct s3c_ide_info *info;
        struct resource *res;
        struct ata_port *ap;
        struct ata_host *host;
        enum s3c_cpu_type cpu_type;
        int ret;

        cpu_type = platform_get_device_id(pdev)->driver_data;

        info = devm_kzalloc(dev, sizeof(*info), GFP_KERNEL);
        if (!info) {
                dev_err(dev, "failed to allocate memory for device data\n");
                return -ENOMEM;
        }

        info->irq = platform_get_irq(pdev, 0);

        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        if (res == NULL) {
                dev_err(dev, "failed to get mem resource\n");
                return -EINVAL;
        }

        if (!devm_request_mem_region(dev, res->start,
                                resource_size(res), DRV_NAME)) {
                dev_err(dev, "error requesting register region\n");
                return -EBUSY;
        }

        info->ide_addr = devm_ioremap(dev, res->start, resource_size(res));
        if (!info->ide_addr) {
                dev_err(dev, "failed to map IO base address\n");
                return -ENOMEM;
        }

        info->clk = clk_get(&pdev->dev, "cfcon");
        if (IS_ERR(info->clk)) {
                dev_err(dev, "failed to get access to cf controller clock\n");
                ret = PTR_ERR(info->clk);
                info->clk = NULL;
                return ret;
        }

        clk_enable(info->clk);

        /* init ata host */
        host = ata_host_alloc(dev, 1);
        if (!host) {
                dev_err(dev, "failed to allocate ide host\n");
                ret = -ENOMEM;
                goto stop_clk;
        }

        ap = host->ports[0];
        ap->flags |= ATA_FLAG_MMIO;
        ap->pio_mask = ATA_PIO4;

        if (cpu_type == TYPE_S3C64XX) {
                ap->ops = &pata_s3c_port_ops;
                info->sfr_addr = info->ide_addr + 0x1800;
                info->ide_addr += 0x1900;
                info->fifo_status_reg = 0x94;
        } else if (cpu_type == TYPE_S5PC100) {
                ap->ops = &pata_s5p_port_ops;
                info->sfr_addr = info->ide_addr + 0x1800;
                info->ide_addr += 0x1900;
                info->fifo_status_reg = 0x84;
        } else {
                ap->ops = &pata_s5p_port_ops;
                info->fifo_status_reg = 0x84;
        }

        info->cpu_type = cpu_type;

        if (info->irq <= 0) {
                ap->flags |= ATA_FLAG_PIO_POLLING;
                info->irq = 0;
                ata_port_desc(ap, "no IRQ, using PIO polling\n");
        }

        ap->ioaddr.cmd_addr =  info->ide_addr + S3C_ATA_CMD;
        ap->ioaddr.data_addr = info->ide_addr + S3C_ATA_PIO_DTR;
        ap->ioaddr.error_addr = info->ide_addr + S3C_ATA_PIO_FED;
        ap->ioaddr.feature_addr = info->ide_addr + S3C_ATA_PIO_FED;
        ap->ioaddr.nsect_addr = info->ide_addr + S3C_ATA_PIO_SCR;
        ap->ioaddr.lbal_addr = info->ide_addr + S3C_ATA_PIO_LLR;
        ap->ioaddr.lbam_addr = info->ide_addr + S3C_ATA_PIO_LMR;
        ap->ioaddr.lbah_addr = info->ide_addr + S3C_ATA_PIO_LHR;
        ap->ioaddr.device_addr = info->ide_addr + S3C_ATA_PIO_DVR;
        ap->ioaddr.status_addr = info->ide_addr + S3C_ATA_PIO_CSD;
        ap->ioaddr.command_addr = info->ide_addr + S3C_ATA_PIO_CSD;
        ap->ioaddr.altstatus_addr = info->ide_addr + S3C_ATA_PIO_DAD;
        ap->ioaddr.ctl_addr = info->ide_addr + S3C_ATA_PIO_DAD;

        ata_port_desc(ap, "mmio cmd 0x%llx ",
                        (unsigned long long)res->start);

        host->private_data = info;

        if (pdata && pdata->setup_gpio)
                pdata->setup_gpio();

        /* Set endianness and enable the interface */
        pata_s3c_hwinit(info, pdata);

        platform_set_drvdata(pdev, host);

        return ata_host_activate(host, info->irq,
                        info->irq ? pata_s3c_irq : NULL,
                        0, &pata_s3c_sht);

stop_clk:
        clk_disable(info->clk);
        clk_put(info->clk);
        return ret;
}

static int __exit pata_s3c_remove(struct platform_device *pdev)
{
        struct ata_host *host = platform_get_drvdata(pdev);
        struct s3c_ide_info *info = host->private_data;

        ata_host_detach(host);

        clk_disable(info->clk);
        clk_put(info->clk);

        return 0;
}

#ifdef CONFIG_PM
static int pata_s3c_suspend(struct device *dev)
{
        struct platform_device *pdev = to_platform_device(dev);
        struct ata_host *host = platform_get_drvdata(pdev);

        return ata_host_suspend(host, PMSG_SUSPEND);
}

static int pata_s3c_resume(struct device *dev)
{
        struct platform_device *pdev = to_platform_device(dev);
        struct ata_host *host = platform_get_drvdata(pdev);
        struct s3c_ide_platdata *pdata = pdev->dev.platform_data;
        struct s3c_ide_info *info = host->private_data;

        pata_s3c_hwinit(info, pdata);
        ata_host_resume(host);

        return 0;
}

static const struct dev_pm_ops pata_s3c_pm_ops = {
        .suspend        = pata_s3c_suspend,
        .resume         = pata_s3c_resume,
};
#endif

/* driver device registration */
static struct platform_device_id pata_s3c_driver_ids[] = {
        {
                .name           = "s3c64xx-pata",
                .driver_data    = TYPE_S3C64XX,
        }, {
                .name           = "s5pc100-pata",
                .driver_data    = TYPE_S5PC100,
        }, {
                .name           = "s5pv210-pata",
                .driver_data    = TYPE_S5PV210,
        },
        { }
};

MODULE_DEVICE_TABLE(platform, pata_s3c_driver_ids);

static struct platform_driver pata_s3c_driver = {
        .remove         = __exit_p(pata_s3c_remove),
        .id_table       = pata_s3c_driver_ids,
        .driver         = {
                .name   = DRV_NAME,
                .owner  = THIS_MODULE,
#ifdef CONFIG_PM
                .pm     = &pata_s3c_pm_ops,
#endif
        },
};

static int __init pata_s3c_init(void)
{
        return platform_driver_probe(&pata_s3c_driver, pata_s3c_probe);
}

static void __exit pata_s3c_exit(void)
{
        platform_driver_unregister(&pata_s3c_driver);
}

module_init(pata_s3c_init);
module_exit(pata_s3c_exit);

MODULE_AUTHOR("Abhilash Kesavan, <a.kesavan@samsung.com>");
MODULE_DESCRIPTION("low-level driver for Samsung PATA controller");
MODULE_LICENSE("GPL");
MODULE_VERSION(DRV_VERSION);