// SPDX-License-Identifier: GPL-2.0
/* apc - Driver implementation for power management functions
 * of Aurora Personality Chip (APC) on SPARCstation-4/5 and
 * derivatives.
 *
 * Copyright (c) 2002 Eric Brower (ebrower@usa.net)
 */

#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/miscdevice.h>
#include <linux/pm.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/module.h>

#include <asm/io.h>
#include <asm/oplib.h>
#include <linux/uaccess.h>
#include <asm/auxio.h>
#include <asm/apc.h>
#include <asm/processor.h>

/* Debugging
 * 
 * #define APC_DEBUG_LED
 */

#define APC_OBPNAME     "power-management"
#define APC_DEVNAME "apc"

static u8 __iomem *regs;
static int apc_no_idle = 0;

#define apc_readb(offs)         (sbus_readb(regs+offs))
#define apc_writeb(val, offs)   (sbus_writeb(val, regs+offs))

/* Specify "apc=noidle" on the kernel command line to 
 * disable APC CPU standby support.  Certain prototype
 * systems (SPARCstation-Fox) do not play well with APC
 * CPU idle, so disable this if your system has APC and 
 * crashes randomly.
 */
static int __init apc_setup(char *str) 
{
        if(!strncmp(str, "noidle", strlen("noidle"))) {
                apc_no_idle = 1;
                return 1;
        }
        return 0;
}
__setup("apc=", apc_setup);

/* 
 * CPU idle callback function
 * See .../arch/sparc/kernel/process.c
 */
static void apc_swift_idle(void)
{
#ifdef APC_DEBUG_LED
        set_auxio(0x00, AUXIO_LED); 
#endif

        apc_writeb(apc_readb(APC_IDLE_REG) | APC_IDLE_ON, APC_IDLE_REG);

#ifdef APC_DEBUG_LED
        set_auxio(AUXIO_LED, 0x00); 
#endif
} 

static inline void apc_free(struct platform_device *op)
{
        of_iounmap(&op->resource[0], regs, resource_size(&op->resource[0]));
}

static int apc_open(struct inode *inode, struct file *f)
{
        return 0;
}

static int apc_release(struct inode *inode, struct file *f)
{
        return 0;
}

static long apc_ioctl(struct file *f, unsigned int cmd, unsigned long __arg)
{
        __u8 inarg, __user *arg = (__u8 __user *) __arg;

        switch (cmd) {
        case APCIOCGFANCTL:
                if (put_user(apc_readb(APC_FANCTL_REG) & APC_REGMASK, arg))
                        return -EFAULT;
                break;

        case APCIOCGCPWR:
                if (put_user(apc_readb(APC_CPOWER_REG) & APC_REGMASK, arg))
                        return -EFAULT;
                break;

        case APCIOCGBPORT:
                if (put_user(apc_readb(APC_BPORT_REG) & APC_BPMASK, arg))
                        return -EFAULT;
                break;

        case APCIOCSFANCTL:
                if (get_user(inarg, arg))
                        return -EFAULT;
                apc_writeb(inarg & APC_REGMASK, APC_FANCTL_REG);
                break;

        case APCIOCSCPWR:
                if (get_user(inarg, arg))
                        return -EFAULT;
                apc_writeb(inarg & APC_REGMASK, APC_CPOWER_REG);
                break;

        case APCIOCSBPORT:
                if (get_user(inarg, arg))
                        return -EFAULT;
                apc_writeb(inarg & APC_BPMASK, APC_BPORT_REG);
                break;

        default:
                return -EINVAL;
        }

        return 0;
}

static const struct file_operations apc_fops = {
        .unlocked_ioctl =       apc_ioctl,
        .open =                 apc_open,
        .release =              apc_release,
        .llseek =               noop_llseek,
};

static struct miscdevice apc_miscdev = { MISC_DYNAMIC_MINOR, APC_DEVNAME, &apc_fops };

static int apc_probe(struct platform_device *op)
{
        int err;

        regs = of_ioremap(&op->resource[0], 0,
                          resource_size(&op->resource[0]), APC_OBPNAME);
        if (!regs) {
                printk(KERN_ERR "%s: unable to map registers\n", APC_DEVNAME);
                return -ENODEV;
        }

        err = misc_register(&apc_miscdev);
        if (err) {
                printk(KERN_ERR "%s: unable to register device\n", APC_DEVNAME);
                apc_free(op);
                return -ENODEV;
        }

        /* Assign power management IDLE handler */
        if (!apc_no_idle)
                sparc_idle = apc_swift_idle;

        printk(KERN_INFO "%s: power management initialized%s\n", 
               APC_DEVNAME, apc_no_idle ? " (CPU idle disabled)" : "");

        return 0;
}

static const struct of_device_id apc_match[] = {
        {
                .name = APC_OBPNAME,
        },
        {},
};
MODULE_DEVICE_TABLE(of, apc_match);

static struct platform_driver apc_driver = {
        .driver = {
                .name = "apc",
                .of_match_table = apc_match,
        },
        .probe          = apc_probe,
};

static int __init apc_init(void)
{
        return platform_driver_register(&apc_driver);
}

/* This driver is not critical to the boot process
 * and is easiest to ioremap when SBus is already
 * initialized, so we install ourselves thusly:
 */
__initcall(apc_init);