// SPDX-License-Identifier: GPL-2.0-only
/*
 *  arch/arm/mac-sa1100/jornada720_ssp.c
 *
 *  Copyright (C) 2006/2007 Kristoffer Ericson <Kristoffer.Ericson@gmail.com>
 *   Copyright (C) 2006 Filip Zyzniewski <filip.zyzniewski@tefnet.pl>
 *
 *  SSP driver for the HP Jornada 710/720/728
 */

#include <linux/delay.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/sched.h>
#include <linux/io.h>

#include <mach/hardware.h>
#include <mach/jornada720.h>
#include <asm/hardware/ssp.h>

static DEFINE_SPINLOCK(jornada_ssp_lock);
static unsigned long jornada_ssp_flags;

/**
 * jornada_ssp_reverse - reverses input byte
 * @byte: input byte to reverse
 *
 * we need to reverse all data we receive from the mcu due to its physical location
 * returns : 01110111 -> 11101110
 */
inline u8 jornada_ssp_reverse(u8 byte)
{
        return
                ((0x80 & byte) >> 7) |
                ((0x40 & byte) >> 5) |
                ((0x20 & byte) >> 3) |
                ((0x10 & byte) >> 1) |
                ((0x08 & byte) << 1) |
                ((0x04 & byte) << 3) |
                ((0x02 & byte) << 5) |
                ((0x01 & byte) << 7);
};
EXPORT_SYMBOL(jornada_ssp_reverse);

/**
 * jornada_ssp_byte - waits for ready ssp bus and sends byte
 * @byte: input byte to transmit
 *
 * waits for fifo buffer to clear and then transmits, if it doesn't then we will
 * timeout after <timeout> rounds. Needs mcu running before its called.
 *
 * returns : %mcu output on success
 *         : %-ETIMEDOUT on timeout
 */
int jornada_ssp_byte(u8 byte)
{
        int timeout = 400000;
        u16 ret;

        while ((GPLR & GPIO_GPIO10)) {
                if (!--timeout) {
                        printk(KERN_WARNING "SSP: timeout while waiting for transmit\n");
                        return -ETIMEDOUT;
                }
                cpu_relax();
        }

        ret = jornada_ssp_reverse(byte) << 8;

        ssp_write_word(ret);
        ssp_read_word(&ret);

        return jornada_ssp_reverse(ret);
};
EXPORT_SYMBOL(jornada_ssp_byte);

/**
 * jornada_ssp_inout - decide if input is command or trading byte
 * @byte: input byte to send (may be %TXDUMMY)
 *
 * returns : (jornada_ssp_byte(byte)) on success
 *         : %-ETIMEDOUT on timeout failure
 */
int jornada_ssp_inout(u8 byte)
{
        int ret, i;

        /* true means command byte */
        if (byte != TXDUMMY) {
                ret = jornada_ssp_byte(byte);
                /* Proper return to commands is TxDummy */
                if (ret != TXDUMMY) {
                        for (i = 0; i < 256; i++)/* flushing bus */
                                if (jornada_ssp_byte(TXDUMMY) == -1)
                                        break;
                        return -ETIMEDOUT;
                }
        } else /* Exchange TxDummy for data */
                ret = jornada_ssp_byte(TXDUMMY);

        return ret;
};
EXPORT_SYMBOL(jornada_ssp_inout);

/**
 * jornada_ssp_start - enable mcu
 *
 */
void jornada_ssp_start(void)
{
        spin_lock_irqsave(&jornada_ssp_lock, jornada_ssp_flags);
        GPCR = GPIO_GPIO25;
        udelay(50);
        return;
};
EXPORT_SYMBOL(jornada_ssp_start);

/**
 * jornada_ssp_end - disable mcu and turn off lock
 *
 */
void jornada_ssp_end(void)
{
        GPSR = GPIO_GPIO25;
        spin_unlock_irqrestore(&jornada_ssp_lock, jornada_ssp_flags);
        return;
};
EXPORT_SYMBOL(jornada_ssp_end);

static int jornada_ssp_probe(struct platform_device *dev)
{
        int ret;

        GPSR = GPIO_GPIO25;

        ret = ssp_init();

        /* worked fine, lets not bother with anything else */
        if (!ret) {
                printk(KERN_INFO "SSP: device initialized with irq\n");
                return ret;
        }

        printk(KERN_WARNING "SSP: initialization failed, trying non-irq solution \n");

        /* init of Serial 4 port */
        Ser4MCCR0 = 0;
        Ser4SSCR0 = 0x0387;
        Ser4SSCR1 = 0x18;

        /* clear out any left over data */
        ssp_flush();

        /* enable MCU */
        jornada_ssp_start();

        /* see if return value makes sense */
        ret = jornada_ssp_inout(GETBRIGHTNESS);

        /* seems like it worked, just feed it with TxDummy to get rid of data */
        if (ret == TXDUMMY)
                jornada_ssp_inout(TXDUMMY);

        jornada_ssp_end();

        /* failed, lets just kill everything */
        if (ret == -ETIMEDOUT) {
                printk(KERN_WARNING "SSP: attempts failed, bailing\n");
                ssp_exit();
                return -ENODEV;
        }

        /* all fine */
        printk(KERN_INFO "SSP: device initialized\n");
        return 0;
};

static void jornada_ssp_remove(struct platform_device *dev)
{
        /* Note that this doesn't actually remove the driver, since theres nothing to remove
         * It just makes sure everything is turned off */
        GPSR = GPIO_GPIO25;
        ssp_exit();
};

struct platform_driver jornadassp_driver = {
        .probe  = jornada_ssp_probe,
        .remove = jornada_ssp_remove,
        .driver = {
                .name   = "jornada_ssp",
        },
};

static int __init jornada_ssp_init(void)
{
        return platform_driver_register(&jornadassp_driver);
}

module_init(jornada_ssp_init);