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/*

 *      Sky CPU State Driver

 *

 *      Copyright (C) 2002 Brian Waite

 *

 *      This driver allows use of the CPU state bits

 *      It exports the /dev/sky_cpustate and also

 *      /proc/sky_cpustate pseudo-file for status information.

 *

 *      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.

 *

 */

#include <linux/module.h>

#include <linux/kernel.h>

#include <linux/spinlock.h>

#include <linux/miscdevice.h>

#include <linux/proc_fs.h>

#include <linux/hdpu_features.h>

#include <linux/platform_device.h>

#include <asm/uaccess.h>

#include <linux/seq_file.h>

#include <asm/io.h>

#define SKY_CPUSTATE_VERSION            "1.1"

static int hdpu_cpustate_probe(struct platform_device *pdev);

static int hdpu_cpustate_remove(struct platform_device *pdev);

static unsigned char cpustate_get_state(void);

static int cpustate_proc_open(struct inode *inode, struct file *file);

static int cpustate_proc_read(struct seq_file *seq, void *offset);

static struct cpustate_t cpustate;

static const struct file_operations proc_cpustate = {

        .open = cpustate_proc_open,

        .read = seq_read,

        .llseek = seq_lseek,

        .release = single_release,

        .owner = THIS_MODULE,

};

static int cpustate_proc_open(struct inode *inode, struct file *file)

{

        return single_open(file, cpustate_proc_read, NULL);

}

static int cpustate_proc_read(struct seq_file *seq, void *offset)

{

        seq_printf(seq, "CPU State: %04x\n", cpustate_get_state());

        return 0;

}

static int cpustate_get_ref(int excl)

{

        int retval = -EBUSY;

        spin_lock(&cpustate.lock);

        if (cpustate.excl)

                goto out_busy;

        if (excl) {

                if (cpustate.open_count)

                        goto out_busy;

                cpustate.excl = 1;

        }

        cpustate.open_count++;

        retval = 0;

      out_busy:

        spin_unlock(&cpustate.lock);

        return retval;

}

static int cpustate_free_ref(void)

{

        spin_lock(&cpustate.lock);

        cpustate.excl = 0;

        cpustate.open_count--;

        spin_unlock(&cpustate.lock);

        return 0;

}

static unsigned char cpustate_get_state(void)

{

        return cpustate.cached_val;

}

static void cpustate_set_state(unsigned char new_state)

{

        unsigned int state = (new_state << 21);

#ifdef DEBUG_CPUSTATE

        printk("CPUSTATE -> 0x%x\n", new_state);

#endif

        spin_lock(&cpustate.lock);

        cpustate.cached_val = new_state;

        writel((0xff << 21), cpustate.clr_addr);

        writel(state, cpustate.set_addr);

        spin_unlock(&cpustate.lock);

}

/*

 *      Now all the various file operations that we export.

 */

static ssize_t cpustate_read(struct file *file, char *buf,

                             size_t count, loff_t * ppos)

{

        unsigned char data;

        if (count < 0)

                return -EFAULT;

        if (count == 0)

                return 0;

        data = cpustate_get_state();

        if (copy_to_user(buf, &data, sizeof(unsigned char)))

                return -EFAULT;

        return sizeof(unsigned char);

}

static ssize_t cpustate_write(struct file *file, const char *buf,

                              size_t count, loff_t * ppos)

{

        unsigned char data;

        if (count < 0)

                return -EFAULT;

        if (count == 0)

                return 0;

        if (copy_from_user((unsigned char *)&data, buf, sizeof(unsigned char)))

                return -EFAULT;

        cpustate_set_state(data);

        return sizeof(unsigned char);

}

static int cpustate_open(struct inode *inode, struct file *file)

{

        return cpustate_get_ref((file->f_flags & O_EXCL));

}

static int cpustate_release(struct inode *inode, struct file *file)

{

        return cpustate_free_ref();

}

static struct platform_driver hdpu_cpustate_driver = {

        .probe = hdpu_cpustate_probe,

        .remove = hdpu_cpustate_remove,

        .driver = {

                .name = HDPU_CPUSTATE_NAME,

        },

};

/*

 *      The various file operations we support.

 */

static const struct file_operations cpustate_fops = {

      .owner    = THIS_MODULE,

      .open     = cpustate_open,

      .release  = cpustate_release,

      .read     = cpustate_read,

      .write    = cpustate_write,

      .llseek   = no_llseek,

};

static struct miscdevice cpustate_dev = {

        .minor  = MISC_DYNAMIC_MINOR,

        .name   = "sky_cpustate",

        .fops   = &cpustate_fops,

};

static int hdpu_cpustate_probe(struct platform_device *pdev)

{

        struct resource *res;

        struct proc_dir_entry *proc_de;

        int ret;

        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);

        if (!res) {

                printk(KERN_ERR "sky_cpustate: "

                       "Invalid memory resource.\n");

                return -EINVAL;

        }

        cpustate.set_addr = (unsigned long *)res->start;

        cpustate.clr_addr = (unsigned long *)res->end - 1;

        ret = misc_register(&cpustate_dev);

        if (ret) {

                printk(KERN_WARNING "sky_cpustate: "

                       "Unable to register misc device.\n");

                cpustate.set_addr = NULL;

                cpustate.clr_addr = NULL;

                return ret;

        }

        proc_de = create_proc_entry("sky_cpustate", 0666, &proc_root);

        if (!proc_de) {

                printk(KERN_WARNING "sky_cpustate: "

                       "Unable to create proc entry\n");

        } else {

                proc_de->proc_fops = &proc_cpustate;

                proc_de->owner = THIS_MODULE;

        }

        printk(KERN_INFO "Sky CPU State Driver v" SKY_CPUSTATE_VERSION "\n");

        return 0;

}

static int hdpu_cpustate_remove(struct platform_device *pdev)

{

        cpustate.set_addr = NULL;

        cpustate.clr_addr = NULL;

        remove_proc_entry("sky_cpustate", NULL);

        misc_deregister(&cpustate_dev);

        return 0;

}

static int __init cpustate_init(void)

{

        return platform_driver_register(&hdpu_cpustate_driver);

}

static void __exit cpustate_exit(void)

{

        platform_driver_unregister(&hdpu_cpustate_driver);

}

module_init(cpustate_init);

module_exit(cpustate_exit);

MODULE_AUTHOR("Brian Waite");

MODULE_LICENSE("GPL");