/*
   * Copyright (C) 2005 MIPS Technologies, Inc.  All rights reserved.
   *
   *  This program is free software; you can distribute it and/or modify it
   *  under the terms of the GNU General Public License (Version 2) as
   *  published by the Free Software Foundation.
   *
   *  This program is distributed in the hope 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.,
   *  59 Temple Place - Suite 330, Boston MA 02111-1307, USA.
   *
   */
  #include <linux/kernel.h>
  #include <linux/module.h>

  #include <linux/sched.h>

  #include <linux/unistd.h>
  #include <linux/file.h>

  #include <linux/fdtable.h>

  #include <linux/fs.h>
  #include <linux/syscalls.h>
  #include <linux/workqueue.h>
  #include <linux/errno.h>
  #include <linux/list.h>
  
  #include <asm/vpe.h>
  #include <asm/rtlx.h>
  #include <asm/kspd.h>

  static struct workqueue_struct *workqueue;

  static struct work_struct work;
  
  extern unsigned long cpu_khz;
  
  struct mtsp_syscall {
  	int cmd;
  	unsigned char abi;
  	unsigned char size;
  };
  
  struct mtsp_syscall_ret {
  	int retval;
  	int errno;
  };
  
  struct mtsp_syscall_generic {
  	int arg0;
  	int arg1;
  	int arg2;
  	int arg3;
  	int arg4;
  	int arg5;
  	int arg6;
  };
  
  static struct list_head kspd_notifylist;

  static int sp_stopping;

  
  /* these should match with those in the SDE kit */
  #define MTSP_SYSCALL_BASE	0
  #define MTSP_SYSCALL_EXIT	(MTSP_SYSCALL_BASE + 0)
  #define MTSP_SYSCALL_OPEN	(MTSP_SYSCALL_BASE + 1)
  #define MTSP_SYSCALL_READ	(MTSP_SYSCALL_BASE + 2)
  #define MTSP_SYSCALL_WRITE	(MTSP_SYSCALL_BASE + 3)
  #define MTSP_SYSCALL_CLOSE	(MTSP_SYSCALL_BASE + 4)
  #define MTSP_SYSCALL_LSEEK32	(MTSP_SYSCALL_BASE + 5)
  #define MTSP_SYSCALL_ISATTY	(MTSP_SYSCALL_BASE + 6)
  #define MTSP_SYSCALL_GETTIME	(MTSP_SYSCALL_BASE + 7)
  #define MTSP_SYSCALL_PIPEFREQ	(MTSP_SYSCALL_BASE + 8)
  #define MTSP_SYSCALL_GETTOD	(MTSP_SYSCALL_BASE + 9)

  #define MTSP_SYSCALL_IOCTL     (MTSP_SYSCALL_BASE + 10)

  
  #define MTSP_O_RDONLY		0x0000
  #define MTSP_O_WRONLY		0x0001
  #define MTSP_O_RDWR		0x0002
  #define MTSP_O_NONBLOCK		0x0004
  #define MTSP_O_APPEND		0x0008
  #define MTSP_O_SHLOCK		0x0010
  #define MTSP_O_EXLOCK		0x0020
  #define MTSP_O_ASYNC		0x0040

  /* XXX: check which of these is actually O_SYNC vs O_DSYNC */

  #define MTSP_O_FSYNC		O_SYNC
  #define MTSP_O_NOFOLLOW		0x0100
  #define MTSP_O_SYNC		0x0080
  #define MTSP_O_CREAT		0x0200
  #define MTSP_O_TRUNC		0x0400
  #define MTSP_O_EXCL		0x0800
  #define MTSP_O_BINARY		0x8000

  extern int tclimit;

  
  struct apsp_table  {
  	int sp;
  	int ap;
  };
  
  /* we might want to do the mode flags too */
  struct apsp_table open_flags_table[] = {
  	{ MTSP_O_RDWR, O_RDWR },
  	{ MTSP_O_WRONLY, O_WRONLY },
  	{ MTSP_O_CREAT, O_CREAT },
  	{ MTSP_O_TRUNC, O_TRUNC },
  	{ MTSP_O_NONBLOCK, O_NONBLOCK },
  	{ MTSP_O_APPEND, O_APPEND },
  	{ MTSP_O_NOFOLLOW, O_NOFOLLOW }
  };
  
  struct apsp_table syscall_command_table[] = {
  	{ MTSP_SYSCALL_OPEN, __NR_open },
  	{ MTSP_SYSCALL_CLOSE, __NR_close },
  	{ MTSP_SYSCALL_READ, __NR_read },
  	{ MTSP_SYSCALL_WRITE, __NR_write },

  	{ MTSP_SYSCALL_LSEEK32, __NR_lseek },
  	{ MTSP_SYSCALL_IOCTL, __NR_ioctl }

  };
  
  static int sp_syscall(int num, int arg0, int arg1, int arg2, int arg3)
  {

  	register long int _num  __asm__("$2") = num;
  	register long int _arg0  __asm__("$4") = arg0;
  	register long int _arg1  __asm__("$5") = arg1;
  	register long int _arg2  __asm__("$6") = arg2;
  	register long int _arg3  __asm__("$7") = arg3;

  
  	mm_segment_t old_fs;
  
  	old_fs = get_fs();
   	set_fs(KERNEL_DS);
  
    	__asm__ __volatile__ (
   	"	syscall					
  "
   	: "=r" (_num), "=r" (_arg3)
   	: "r" (_num), "r" (_arg0), "r" (_arg1), "r" (_arg2), "r" (_arg3));
  
  	set_fs(old_fs);
  
  	/* $a3 is error flag */
  	if (_arg3)
  		return -_num;
  
  	return _num;
  }
  
  static int translate_syscall_command(int cmd)
  {
  	int i;
  	int ret = -1;
  
  	for (i = 0; i < ARRAY_SIZE(syscall_command_table); i++) {
  		if ((cmd == syscall_command_table[i].sp))
  			return syscall_command_table[i].ap;
  	}
  
  	return ret;
  }
  
  static unsigned int translate_open_flags(int flags)
  {
  	int i;
  	unsigned int ret = 0;

  	for (i = 0; i < ARRAY_SIZE(open_flags_table); i++) {

  		if( (flags & open_flags_table[i].sp) ) {
  			ret |= open_flags_table[i].ap;
  		}
  	}
  
  	return ret;
  }

  static int sp_setfsuidgid(uid_t uid, gid_t gid)

  {

  	struct cred *new;

  	new = prepare_creds();
  	if (!new)
  		return -ENOMEM;
  
  	new->fsuid = uid;
  	new->fsgid = gid;
  
  	commit_creds(new);
  
  	return 0;

  }
  
  /*
   * Expects a request to be on the sysio channel. Reads it.  Decides whether
   * its a linux syscall and runs it, or whatever.  Puts the return code back
   * into the request and sends the whole thing back.
   */
  void sp_work_handle_request(void)
  {
  	struct mtsp_syscall sc;
  	struct mtsp_syscall_generic generic;
  	struct mtsp_syscall_ret ret;
  	struct kspd_notifications *n;

  	unsigned long written;
  	mm_segment_t old_fs;

  	struct timeval tv;
  	struct timezone tz;

  	int err, cmd;

  
  	char *vcwd;

  	int size;
  
  	ret.retval = -1;

  	old_fs = get_fs();
  	set_fs(KERNEL_DS);
  
  	if (!rtlx_read(RTLX_CHANNEL_SYSIO, &sc, sizeof(struct mtsp_syscall))) {
  		set_fs(old_fs);

  		printk(KERN_ERR "Expected request but nothing to read
  ");
  		return;
  	}
  
  	size = sc.size;
  
  	if (size) {

  		if (!rtlx_read(RTLX_CHANNEL_SYSIO, &generic, size)) {
  			set_fs(old_fs);

  			printk(KERN_ERR "Expected request but nothing to read
  ");
  			return;
  		}
  	}

  	/* Run the syscall at the privilege of the user who loaded the

  	   SP program */

  	if (vpe_getuid(tclimit)) {
  		err = sp_setfsuidgid(vpe_getuid(tclimit), vpe_getgid(tclimit));
  		if (!err)
  			pr_err("Change of creds failed
  ");
  	}

  
  	switch (sc.cmd) {
  	/* needs the flags argument translating from SDE kit to
  	   linux */
   	case MTSP_SYSCALL_PIPEFREQ:
   		ret.retval = cpu_khz * 1000;
   		ret.errno = 0;
   		break;
  
   	case MTSP_SYSCALL_GETTOD:
   		memset(&tz, 0, sizeof(tz));
   		if ((ret.retval = sp_syscall(__NR_gettimeofday, (int)&tv,

  					     (int)&tz, 0, 0)) == 0)

  			ret.retval = tv.tv_sec;

  		break;
  
   	case MTSP_SYSCALL_EXIT:
  		list_for_each_entry(n, &kspd_notifylist, list)

  			n->kspd_sp_exit(tclimit);

  		sp_stopping = 1;
  
  		printk(KERN_DEBUG "KSPD got exit syscall from SP exitcode %d
  ",
  		       generic.arg0);
   		break;
  
   	case MTSP_SYSCALL_OPEN:
   		generic.arg1 = translate_open_flags(generic.arg1);

  		vcwd = vpe_getcwd(tclimit);

  		/* change to cwd of the process that loaded the SP program */

  		old_fs = get_fs();
  		set_fs(KERNEL_DS);
  		sys_chdir(vcwd);
  		set_fs(old_fs);
  
   		sc.cmd = __NR_open;
  
  		/* fall through */
  
    	default:
   		if ((sc.cmd >= __NR_Linux) &&
  		    (sc.cmd <= (__NR_Linux +  __NR_Linux_syscalls)) )
  			cmd = sc.cmd;
  		else
  			cmd = translate_syscall_command(sc.cmd);
  
  		if (cmd >= 0) {
  			ret.retval = sp_syscall(cmd, generic.arg0, generic.arg1,
  			                        generic.arg2, generic.arg3);

  		} else
   			printk(KERN_WARNING
  			       "KSPD: Unknown SP syscall number %d
  ", sc.cmd);
  		break;
   	} /* switch */

  	if (vpe_getuid(tclimit)) {
  		err = sp_setfsuidgid(0, 0);
  		if (!err)
  			pr_err("restoring old creds failed
  ");
  	}

  	old_fs = get_fs();
  	set_fs(KERNEL_DS);
  	written = rtlx_write(RTLX_CHANNEL_SYSIO, &ret, sizeof(ret));
  	set_fs(old_fs);
  	if (written < sizeof(ret))

  		printk("KSPD: sp_work_handle_request failed to send to SP
  ");
  }
  
  static void sp_cleanup(void)
  {
  	struct files_struct *files = current->files;
  	int i, j;
  	struct fdtable *fdt;
  
  	j = 0;
  
  	/*
  	 * It is safe to dereference the fd table without RCU or
  	 * ->file_lock
  	 */
  	fdt = files_fdtable(files);
  	for (;;) {
  		unsigned long set;
  		i = j * __NFDBITS;

  		if (i >= fdt->max_fds)

  			break;
  		set = fdt->open_fds->fds_bits[j++];
  		while (set) {
  			if (set & 1) {
  				struct file * file = xchg(&fdt->fd[i], NULL);
  				if (file)
  					filp_close(file, files);
  			}
  			i++;
  			set >>= 1;
  		}
  	}

  
  	/* Put daemon cwd back to root to avoid umount problems */
  	sys_chdir("/");

  }

  static int channel_open;

  
  /* the work handler */

  static void sp_work(struct work_struct *unused)

  {
  	if (!channel_open) {
  		if( rtlx_open(RTLX_CHANNEL_SYSIO, 1) != 0) {
  			printk("KSPD: unable to open sp channel
  ");
  			sp_stopping = 1;
  		} else {
  			channel_open++;
  			printk(KERN_DEBUG "KSPD: SP channel opened
  ");
  		}
  	} else {
  		/* wait for some data, allow it to sleep */
  		rtlx_read_poll(RTLX_CHANNEL_SYSIO, 1);
  
  		/* Check we haven't been woken because we are stopping */
  		if (!sp_stopping)
  			sp_work_handle_request();
  	}
  
  	if (!sp_stopping)
  		queue_work(workqueue, &work);
  	else
  		sp_cleanup();
  }
  
  static void startwork(int vpe)
  {
  	sp_stopping = channel_open = 0;
  
  	if (workqueue == NULL) {
  		if ((workqueue = create_singlethread_workqueue("kspd")) == NULL) {
  			printk(KERN_ERR "unable to start kspd
  ");
  			return;
  		}

  		INIT_WORK(&work, sp_work);

  	}

  	queue_work(workqueue, &work);

  }
  
  static void stopwork(int vpe)
  {
  	sp_stopping = 1;
  
  	printk(KERN_DEBUG "KSPD: SP stopping
  ");
  }
  
  void kspd_notify(struct kspd_notifications *notify)
  {
  	list_add(&notify->list, &kspd_notifylist);
  }
  
  static struct vpe_notifications notify;
  static int kspd_module_init(void)
  {
  	INIT_LIST_HEAD(&kspd_notifylist);
  
  	notify.start = startwork;
  	notify.stop = stopwork;

  	vpe_notify(tclimit, &notify);

  
  	return 0;
  }
  
  static void kspd_module_exit(void)
  {
  
  }
  
  module_init(kspd_module_init);
  module_exit(kspd_module_exit);
  
  MODULE_DESCRIPTION("MIPS KSPD");
  MODULE_AUTHOR("Elizabeth Oldham, MIPS Technologies, Inc.");
  MODULE_LICENSE("GPL");