/*
 * IDE host driver for AT91 (SAM9, CAP9, AT572D940HF) Static Memory Controller
 * with Compact Flash True IDE logic
 *
 * Copyright (c) 2008, 2009 Kelvatek Ltd.
 *
 *  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.
 *
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/clk.h>
#include <linux/err.h>
#include <linux/ide.h>
#include <linux/platform_device.h>

#include <mach/board.h>
#include <mach/gpio.h>
#include <mach/at91sam9_smc.h>

#define DRV_NAME "at91_ide"

#define perr(fmt, args...) pr_err(DRV_NAME ": " fmt, ##args)
#define pdbg(fmt, args...) pr_debug("%s " fmt, __func__, ##args)

/*
 * Access to IDE device is possible through EBI Static Memory Controller
 * with Compact Flash logic. For details see EBI and SMC datasheet sections
 * of any microcontroller from AT91SAM9 family.
 *
 * Within SMC chip select address space, lines A[23:21] distinguish Compact
 * Flash modes (I/O, common memory, attribute memory, True IDE). IDE modes are:
 *   0x00c0000 - True IDE
 *   0x00e0000 - Alternate True IDE (Alt Status Register)
 *
 * On True IDE mode Task File and Data Register are mapped at the same address.
 * To distinguish access between these two different bus data width is used:
 * 8Bit for Task File, 16Bit for Data I/O.
 *
 * After initialization we do 8/16 bit flipping (changes in SMC MODE register)
 * only inside IDE callback routines which are serialized by IDE layer,
 * so no additional locking needed.
 */

#define TASK_FILE       0x00c00000
#define ALT_MODE        0x00e00000
#define REGS_SIZE       8

#define enter_16bit(cs, mode) do {                                      \
        mode = at91_sys_read(AT91_SMC_MODE(cs));                        \
        at91_sys_write(AT91_SMC_MODE(cs), mode | AT91_SMC_DBW_16);      \
} while (0)

#define leave_16bit(cs, mode) at91_sys_write(AT91_SMC_MODE(cs), mode);

static void set_smc_timings(const u8 chipselect, const u16 cycle,
                            const u16 setup, const u16 pulse,
                            const u16 data_float, int use_iordy)
{
        unsigned long mode = AT91_SMC_READMODE | AT91_SMC_WRITEMODE |
                             AT91_SMC_BAT_SELECT;

        /* disable or enable waiting for IORDY signal */
        if (use_iordy)
                mode |= AT91_SMC_EXNWMODE_READY;

        /* add data float cycles if needed */
        if (data_float)
                mode |= AT91_SMC_TDF_(data_float);

        at91_sys_write(AT91_SMC_MODE(chipselect), mode);

        /* setup timings in SMC */
        at91_sys_write(AT91_SMC_SETUP(chipselect), AT91_SMC_NWESETUP_(setup) |
                                                   AT91_SMC_NCS_WRSETUP_(0) |
                                                   AT91_SMC_NRDSETUP_(setup) |
                                                   AT91_SMC_NCS_RDSETUP_(0));
        at91_sys_write(AT91_SMC_PULSE(chipselect), AT91_SMC_NWEPULSE_(pulse) |
                                                   AT91_SMC_NCS_WRPULSE_(cycle) |
                                                   AT91_SMC_NRDPULSE_(pulse) |
                                                   AT91_SMC_NCS_RDPULSE_(cycle));
        at91_sys_write(AT91_SMC_CYCLE(chipselect), AT91_SMC_NWECYCLE_(cycle) |
                                                   AT91_SMC_NRDCYCLE_(cycle));
}

static unsigned int calc_mck_cycles(unsigned int ns, unsigned int mck_hz)
{
        u64 tmp = ns;

        tmp *= mck_hz;
        tmp += 1000*1000*1000 - 1; /* round up */
        do_div(tmp, 1000*1000*1000);
        return (unsigned int) tmp;
}

static void apply_timings(const u8 chipselect, const u8 pio,
                          const struct ide_timing *timing, int use_iordy)
{
        unsigned int t0, t1, t2, t6z;
        unsigned int cycle, setup, pulse, data_float;
        unsigned int mck_hz;
        struct clk *mck;

        /* see table 22 of Compact Flash standard 4.1 for the meaning,
         * we do not stretch active (t2) time, so setup (t1) + hold time (th)
         * assure at least minimal recovery (t2i) time */
        t0 = timing->cyc8b;
        t1 = timing->setup;
        t2 = timing->act8b;
        t6z = (pio < 5) ? 30 : 20;

        pdbg("t0=%u t1=%u t2=%u t6z=%u\n", t0, t1, t2, t6z);

        mck = clk_get(NULL, "mck");
        BUG_ON(IS_ERR(mck));
        mck_hz = clk_get_rate(mck);
        pdbg("mck_hz=%u\n", mck_hz);

        cycle = calc_mck_cycles(t0, mck_hz);
        setup = calc_mck_cycles(t1, mck_hz);
        pulse = calc_mck_cycles(t2, mck_hz);
        data_float = calc_mck_cycles(t6z, mck_hz);

        pdbg("cycle=%u setup=%u pulse=%u data_float=%u\n",
             cycle, setup, pulse, data_float);

        set_smc_timings(chipselect, cycle, setup, pulse, data_float, use_iordy);
}

static void at91_ide_input_data(ide_drive_t *drive, struct ide_cmd *cmd,
                                void *buf, unsigned int len)
{
        ide_hwif_t *hwif = drive->hwif;
        struct ide_io_ports *io_ports = &hwif->io_ports;
        u8 chipselect = hwif->select_data;
        unsigned long mode;

        pdbg("cs %u buf %p len %d\n", chipselect, buf, len);

        len++;

        enter_16bit(chipselect, mode);
        readsw((void __iomem *)io_ports->data_addr, buf, len / 2);
        leave_16bit(chipselect, mode);
}

static void at91_ide_output_data(ide_drive_t *drive, struct ide_cmd *cmd,
                                 void *buf, unsigned int len)
{
        ide_hwif_t *hwif = drive->hwif;
        struct ide_io_ports *io_ports = &hwif->io_ports;
        u8 chipselect = hwif->select_data;
        unsigned long mode;

        pdbg("cs %u buf %p len %d\n", chipselect,  buf, len);

        enter_16bit(chipselect, mode);
        writesw((void __iomem *)io_ports->data_addr, buf, len / 2);
        leave_16bit(chipselect, mode);
}

static void at91_ide_set_pio_mode(ide_hwif_t *hwif, ide_drive_t *drive)
{
        struct ide_timing *timing;
        u8 chipselect = hwif->select_data;
        int use_iordy = 0;
        const u8 pio = drive->pio_mode - XFER_PIO_0;

        pdbg("chipselect %u pio %u\n", chipselect, pio);

        timing = ide_timing_find_mode(XFER_PIO_0 + pio);
        BUG_ON(!timing);

        if (ide_pio_need_iordy(drive, pio))
                use_iordy = 1;

        apply_timings(chipselect, pio, timing, use_iordy);
}

static const struct ide_tp_ops at91_ide_tp_ops = {
        .exec_command   = ide_exec_command,
        .read_status    = ide_read_status,
        .read_altstatus = ide_read_altstatus,
        .write_devctl   = ide_write_devctl,

        .dev_select     = ide_dev_select,
        .tf_load        = ide_tf_load,
        .tf_read        = ide_tf_read,

        .input_data     = at91_ide_input_data,
        .output_data    = at91_ide_output_data,
};

static const struct ide_port_ops at91_ide_port_ops = {
        .set_pio_mode   = at91_ide_set_pio_mode,
};

static const struct ide_port_info at91_ide_port_info __initdata = {
        .port_ops       = &at91_ide_port_ops,
        .tp_ops         = &at91_ide_tp_ops,
        .host_flags     = IDE_HFLAG_MMIO | IDE_HFLAG_NO_DMA | IDE_HFLAG_SINGLE |
                          IDE_HFLAG_NO_IO_32BIT | IDE_HFLAG_UNMASK_IRQS,
        .pio_mask       = ATA_PIO6,
        .chipset        = ide_generic,
};

/*
 * If interrupt is delivered through GPIO, IRQ are triggered on falling
 * and rising edge of signal. Whereas IDE device request interrupt on high
 * level (rising edge in our case). This mean we have fake interrupts, so
 * we need to check interrupt pin and exit instantly from ISR when line
 * is on low level.
 */

irqreturn_t at91_irq_handler(int irq, void *dev_id)
{
        int ntries = 8;
        int pin_val1, pin_val2;

        /* additional deglitch, line can be noisy in badly designed PCB */
        do {
                pin_val1 = at91_get_gpio_value(irq);
                pin_val2 = at91_get_gpio_value(irq);
        } while (pin_val1 != pin_val2 && --ntries > 0);

        if (pin_val1 == 0 || ntries <= 0)
                return IRQ_HANDLED;

        return ide_intr(irq, dev_id);
}

static int __init at91_ide_probe(struct platform_device *pdev)
{
        int ret;
        struct ide_hw hw, *hws[] = { &hw };
        struct ide_host *host;
        struct resource *res;
        unsigned long tf_base = 0, ctl_base = 0;
        struct at91_cf_data *board = pdev->dev.platform_data;

        if (!board)
                return -ENODEV;

        if (board->det_pin && at91_get_gpio_value(board->det_pin) != 0) {
                perr("no device detected\n");
                return -ENODEV;
        }

        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        if (!res) {
                perr("can't get memory resource\n");
                return -ENODEV;
        }

        if (!devm_request_mem_region(&pdev->dev, res->start + TASK_FILE,
                                     REGS_SIZE, "ide") ||
            !devm_request_mem_region(&pdev->dev, res->start + ALT_MODE,
                                     REGS_SIZE, "alt")) {
                perr("memory resources in use\n");
                return -EBUSY;
        }

        pdbg("chipselect %u irq %u res %08lx\n", board->chipselect,
             board->irq_pin, (unsigned long) res->start);

        tf_base = (unsigned long) devm_ioremap(&pdev->dev, res->start + TASK_FILE,
                                               REGS_SIZE);
        ctl_base = (unsigned long) devm_ioremap(&pdev->dev, res->start + ALT_MODE,
                                                REGS_SIZE);
        if (!tf_base || !ctl_base) {
                perr("can't map memory regions\n");
                return -EBUSY;
        }

        memset(&hw, 0, sizeof(hw));

        if (board->flags & AT91_IDE_SWAP_A0_A2) {
                /* workaround for stupid hardware bug */
                hw.io_ports.data_addr   = tf_base + 0;
                hw.io_ports.error_addr  = tf_base + 4;
                hw.io_ports.nsect_addr  = tf_base + 2;
                hw.io_ports.lbal_addr   = tf_base + 6;
                hw.io_ports.lbam_addr   = tf_base + 1;
                hw.io_ports.lbah_addr   = tf_base + 5;
                hw.io_ports.device_addr = tf_base + 3;
                hw.io_ports.command_addr = tf_base + 7;
                hw.io_ports.ctl_addr    = ctl_base + 3;
        } else
                ide_std_init_ports(&hw, tf_base, ctl_base + 6);

        hw.irq = board->irq_pin;
        hw.dev = &pdev->dev;

        host = ide_host_alloc(&at91_ide_port_info, hws, 1);
        if (!host) {
                perr("failed to allocate ide host\n");
                return -ENOMEM;
        }

        /* setup Static Memory Controller - PIO 0 as default */
        apply_timings(board->chipselect, 0, ide_timing_find_mode(XFER_PIO_0), 0);

        /* with GPIO interrupt we have to do quirks in handler */
        if (board->irq_pin >= PIN_BASE)
                host->irq_handler = at91_irq_handler;

        host->ports[0]->select_data = board->chipselect;

        ret = ide_host_register(host, &at91_ide_port_info, hws);
        if (ret) {
                perr("failed to register ide host\n");
                goto err_free_host;
        }
        platform_set_drvdata(pdev, host);
        return 0;

err_free_host:
        ide_host_free(host);
        return ret;
}

static int __exit at91_ide_remove(struct platform_device *pdev)
{
        struct ide_host *host = platform_get_drvdata(pdev);

        ide_host_remove(host);
        return 0;
}

static struct platform_driver at91_ide_driver = {
        .driver = {
                .name = DRV_NAME,
                .owner = THIS_MODULE,
        },
        .remove = __exit_p(at91_ide_remove),
};

static int __init at91_ide_init(void)
{
        return platform_driver_probe(&at91_ide_driver, at91_ide_probe);
}

static void __exit at91_ide_exit(void)
{
        platform_driver_unregister(&at91_ide_driver);
}

module_init(at91_ide_init);
module_exit(at91_ide_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Stanislaw Gruszka <stf_xl@wp.pl>");