hwc_rw.c

这个linux源代码是很全面的~基本完整了~使用c编译的~由于时间问题我没有亲自测试~但就算用来做参考资料也是非常好的

/*
 *  drivers/s390/char/hwc_rw.c
 *     driver: reading from and writing to system console on S/390 via HWC
 *
 *  S390 version
 *    Copyright (C) 1999 IBM Deutschland Entwicklung GmbH, IBM Corporation
 *    Author(s): Martin Peschke <[e-mail]>
 *
 * 
 *
 * 
 * 
 * 
 */

#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/errno.h>
#include <linux/ctype.h>
#include <linux/mm.h>
#include <linux/timer.h>
#include <linux/bootmem.h>
#include <linux/module.h>

#include <asm/ebcdic.h>
#include <asm/uaccess.h>
#include <asm/types.h>
#include <asm/bitops.h>
#include <asm/setup.h>
#include <asm/page.h>
#include <asm/s390_ext.h>
#include <asm/irq.h>

#ifndef MIN
#define MIN(a,b) (((a<b) ? a : b))
#endif

extern void ctrl_alt_del (void);

#define HWC_RW_PRINT_HEADER "hwc low level driver: "

#define  USE_VM_DETECTION

#define  DEFAULT_CASE_DELIMITER '%'

#undef DUMP_HWC_INIT_ERROR

#undef DUMP_HWC_WRITE_ERROR

#undef DUMP_HWC_WRITE_LIST_ERROR

#undef DUMP_HWC_READ_ERROR

#undef DUMP_HWCB_INPUT

#undef BUFFER_STRESS_TEST

typedef struct {
	unsigned char *next;
	unsigned short int mto_char_sum;
	unsigned char mto_number;
	unsigned char times_lost;
	unsigned short int mto_number_lost;
	unsigned long int mto_char_sum_lost;
} __attribute__ ((packed)) 

hwcb_list_t;

#define MAX_HWCB_ROOM (PAGE_SIZE - sizeof(hwcb_list_t))

#define MAX_MESSAGE_SIZE (MAX_HWCB_ROOM - sizeof(write_hwcb_t))

#define BUF_HWCB hwc_data.hwcb_list_tail
#define OUT_HWCB hwc_data.hwcb_list_head
#define ALL_HWCB_MTO hwc_data.mto_number
#define ALL_HWCB_CHAR hwc_data.mto_char_sum

#define _LIST(hwcb) ((hwcb_list_t*)(&(hwcb)[PAGE_SIZE-sizeof(hwcb_list_t)]))

#define _HWCB_CHAR(hwcb) (_LIST(hwcb)->mto_char_sum)

#define _HWCB_MTO(hwcb) (_LIST(hwcb)->mto_number)

#define _HWCB_CHAR_LOST(hwcb) (_LIST(hwcb)->mto_char_sum_lost)

#define _HWCB_MTO_LOST(hwcb) (_LIST(hwcb)->mto_number_lost)

#define _HWCB_TIMES_LOST(hwcb) (_LIST(hwcb)->times_lost)

#define _HWCB_NEXT(hwcb) (_LIST(hwcb)->next)

#define BUF_HWCB_CHAR _HWCB_CHAR(BUF_HWCB)

#define BUF_HWCB_MTO _HWCB_MTO(BUF_HWCB)

#define BUF_HWCB_NEXT _HWCB_NEXT(BUF_HWCB)

#define OUT_HWCB_CHAR _HWCB_CHAR(OUT_HWCB)

#define OUT_HWCB_MTO _HWCB_MTO(OUT_HWCB)

#define OUT_HWCB_NEXT _HWCB_NEXT(OUT_HWCB)

#define BUF_HWCB_CHAR_LOST _HWCB_CHAR_LOST(BUF_HWCB)

#define BUF_HWCB_MTO_LOST _HWCB_MTO_LOST(BUF_HWCB)

#define OUT_HWCB_CHAR_LOST _HWCB_CHAR_LOST(OUT_HWCB)

#define OUT_HWCB_MTO_LOST _HWCB_MTO_LOST(OUT_HWCB)

#define BUF_HWCB_TIMES_LOST _HWCB_TIMES_LOST(BUF_HWCB)

#include  "hwc.h"

#define __HWC_RW_C__
#include "hwc_rw.h"
#undef __HWC_RW_C__

static unsigned char _obuf[MAX_HWCB_ROOM];

static unsigned char
 _page[PAGE_SIZE] __attribute__ ((aligned (PAGE_SIZE)));

typedef unsigned long kmem_pages_t;

#define MAX_KMEM_PAGES (sizeof(kmem_pages_t) << 3)

#define HWC_WTIMER_RUNS	1
#define HWC_FLUSH		2
#define HWC_INIT		4
#define HWC_BROKEN		8
#define HWC_INTERRUPT		16
#define HWC_PTIMER_RUNS	32

static struct {

	hwc_ioctls_t ioctls;

	hwc_ioctls_t init_ioctls;

	unsigned char *hwcb_list_head;

	unsigned char *hwcb_list_tail;

	unsigned short int mto_number;

	unsigned int mto_char_sum;

	unsigned char hwcb_count;

	unsigned long kmem_start;

	unsigned long kmem_end;

	kmem_pages_t kmem_pages;

	unsigned char *obuf;

	unsigned short int obuf_cursor;

	unsigned short int obuf_count;

	unsigned short int obuf_start;

	unsigned char *page;

	u32 current_servc;

	unsigned char *current_hwcb;

	unsigned char write_nonprio:1;
	unsigned char write_prio:1;
	unsigned char read_nonprio:1;
	unsigned char read_prio:1;
	unsigned char read_statechange:1;
	unsigned char sig_quiesce:1;

	unsigned char flags;

	hwc_high_level_calls_t *calls;

	hwc_request_t *request;

	spinlock_t lock;

	struct timer_list write_timer;

	struct timer_list poll_timer;
} hwc_data =
{
	{
	},
	{
		8,
		    0,
		    80,
		    1,
		    MAX_KMEM_PAGES,
		    MAX_KMEM_PAGES,

		    0,

		    0x6c

	},
	    NULL,
	    NULL,
	    0,
	    0,
	    0,
	    0,
	    0,
	    0,
	    _obuf,
	    0,
	    0,
	    0,
	    _page,
	    0,
	    NULL,
	    0,
	    0,
	    0,
	    0,
	    0,
	    0,
	    0,
	    NULL,
	    NULL

};

static unsigned long cr0 __attribute__ ((aligned (8)));
static unsigned long cr0_save __attribute__ ((aligned (8)));
static unsigned char psw_mask __attribute__ ((aligned (8)));

static ext_int_info_t ext_int_info_hwc;

#define DELAYED_WRITE 0
#define IMMEDIATE_WRITE 1

static signed int do_hwc_write (int from_user, unsigned char *,
				unsigned int,
				unsigned char);

unsigned char hwc_ip_buf[512];

static asmlinkage int 
internal_print (char write_time, char *fmt,...)
{
	va_list args;
	int i;

	va_start (args, fmt);
	i = vsprintf (hwc_ip_buf, fmt, args);
	va_end (args);
	return do_hwc_write (0, hwc_ip_buf, i, write_time);
}

int 
hwc_printk (const char *fmt,...)
{
	va_list args;
	int i;
	unsigned long flags;
	int retval;

	spin_lock_irqsave (&hwc_data.lock, flags);

	i = vsprintf (hwc_ip_buf, fmt, args);
	va_end (args);
	retval = do_hwc_write (0, hwc_ip_buf, i, IMMEDIATE_WRITE);

	spin_unlock_irqrestore (&hwc_data.lock, flags);

	return retval;
}

#ifdef DUMP_HWCB_INPUT

static void 
dump_storage_area (unsigned char *area, unsigned short int count)
{
	unsigned short int index;
	ioctl_nl_t old_final_nl;

	if (!area || !count)
		return;

	old_final_nl = hwc_data.ioctls.final_nl;
	hwc_data.ioctls.final_nl = 1;

	internal_print (DELAYED_WRITE, "\n%8x   ", area);

	for (index = 0; index < count; index++) {

		if (area[index] <= 0xF)
			internal_print (DELAYED_WRITE, "0%x", area[index]);
		else
			internal_print (DELAYED_WRITE, "%x", area[index]);

		if ((index & 0xF) == 0xF)
			internal_print (DELAYED_WRITE, "\n%8x   ",
					&area[index + 1]);
		else if ((index & 3) == 3)
			internal_print (DELAYED_WRITE, " ");
	}

	internal_print (IMMEDIATE_WRITE, "\n");

	hwc_data.ioctls.final_nl = old_final_nl;
}
#endif

static inline u32 
service_call (
		     u32 hwc_command_word,
		     unsigned char hwcb[])
{
	unsigned int condition_code = 1;

	__asm__ __volatile__ ("L 1, 0(%0) \n\t"
			      "LRA 2, 0(%1) \n\t"
			      ".long 0xB2200012 \n\t"
			      :
			      :"a" (&hwc_command_word), "a" (hwcb)
			      :"1", "2", "memory");

	__asm__ __volatile__ ("IPM %0 \n\t"
			      "SRL %0, 28 \n\t"
			      :"=r" (condition_code));

	return condition_code;
}

static inline unsigned long 
hwc_ext_int_param (void)
{
	u32 param;

	__asm__ __volatile__ ("L %0,128\n\t"
			      :"=r" (param));

	return (unsigned long) param;
}

static int 
prepare_write_hwcb (void)
{
	write_hwcb_t *hwcb;

	if (!BUF_HWCB)
		return -ENOMEM;

	BUF_HWCB_MTO = 0;
	BUF_HWCB_CHAR = 0;

	hwcb = (write_hwcb_t *) BUF_HWCB;

	memcpy (hwcb, &write_hwcb_template, sizeof (write_hwcb_t));

	return 0;
}

static int 
sane_write_hwcb (void)
{
	unsigned short int lost_msg;
	unsigned int lost_char;
	unsigned char lost_hwcb;
	unsigned char *bad_addr;
	unsigned long page;
	int page_nr;

	if (!OUT_HWCB)
		return -ENOMEM;

	if ((unsigned long) OUT_HWCB & 0xFFF) {

		bad_addr = OUT_HWCB;

#ifdef DUMP_HWC_WRITE_LIST_ERROR
		__asm__ ("LHI 1,0xe30\n\t"
			 "LRA 2,0(%0) \n\t"
			 "J .+0 \n\t"
	      :
	      :	 "a" (bad_addr)
	      :	 "1", "2");
#endif

		hwc_data.kmem_pages = 0;
		if ((unsigned long) BUF_HWCB & 0xFFF) {

			lost_hwcb = hwc_data.hwcb_count;
			lost_msg = ALL_HWCB_MTO;
			lost_char = ALL_HWCB_CHAR;

			OUT_HWCB = NULL;
			BUF_HWCB = NULL;
			ALL_HWCB_MTO = 0;
			ALL_HWCB_CHAR = 0;
			hwc_data.hwcb_count = 0;
		} else {

			lost_hwcb = hwc_data.hwcb_count - 1;
			lost_msg = ALL_HWCB_MTO - BUF_HWCB_MTO;
			lost_char = ALL_HWCB_CHAR - BUF_HWCB_CHAR;
			OUT_HWCB = BUF_HWCB;
			ALL_HWCB_MTO = BUF_HWCB_MTO;
			ALL_HWCB_CHAR = BUF_HWCB_CHAR;
			hwc_data.hwcb_count = 1;
			page = (unsigned long) BUF_HWCB;

			if (page >= hwc_data.kmem_start &&
			    page <= hwc_data.kmem_end) {

				page_nr = (int)
				    ((page - hwc_data.kmem_start) >> 12);
				set_bit (page_nr, &hwc_data.kmem_pages);
			}
		}

		internal_print (
				       DELAYED_WRITE,
				       HWC_RW_PRINT_HEADER
		       "found invalid HWCB at address 0x%lx. List corrupted. "
			   "Lost %i HWCBs with %i characters within up to %i "
			   "messages. Saved %i HWCB with last %i characters i"
				       "within up to %i messages.\n",
				       (unsigned long) bad_addr,
				       lost_hwcb, lost_char, lost_msg,
				       hwc_data.hwcb_count,
				       ALL_HWCB_CHAR, ALL_HWCB_MTO);
	}
	return 0;
}

static int 
reuse_write_hwcb (void)
{
	int retval;

	if (hwc_data.hwcb_count < 2)
#ifdef DUMP_HWC_WRITE_LIST_ERROR
		__asm__ ("LHI 1,0xe31\n\t"
			 "LRA 2,0(%0)\n\t"
			 "LRA 3,0(%1)\n\t"
			 "J .+0 \n\t"
	      :
	      :	 "a" (BUF_HWCB), "a" (OUT_HWCB)
	      :	 "1", "2", "3");
#else
		return -EPERM;
#endif

	if (hwc_data.current_hwcb == OUT_HWCB) {

		if (hwc_data.hwcb_count > 2) {

			BUF_HWCB_NEXT = OUT_HWCB_NEXT;

			BUF_HWCB = OUT_HWCB_NEXT;

			OUT_HWCB_NEXT = BUF_HWCB_NEXT;

			BUF_HWCB_NEXT = NULL;
		}
	} else {

		BUF_HWCB_NEXT = OUT_HWCB;

		BUF_HWCB = OUT_HWCB;

		OUT_HWCB = OUT_HWCB_NEXT;

		BUF_HWCB_NEXT = NULL;
	}

	BUF_HWCB_TIMES_LOST += 1;
	BUF_HWCB_CHAR_LOST += BUF_HWCB_CHAR;
	BUF_HWCB_MTO_LOST += BUF_HWCB_MTO;
	ALL_HWCB_MTO -= BUF_HWCB_MTO;
	ALL_HWCB_CHAR -= BUF_HWCB_CHAR;

	retval = prepare_write_hwcb ();

	if (hwc_data.hwcb_count == hwc_data.ioctls.max_hwcb)
		internal_print (
				       DELAYED_WRITE,
				       HWC_RW_PRINT_HEADER
				       "reached my own limit of "
			    "allowed buffer space for output (%i HWCBs = %li "
			  "bytes), skipped content of oldest HWCB %i time(s) "
				       "(%i lines = %i characters)\n",
				       hwc_data.ioctls.max_hwcb,
				       hwc_data.ioctls.max_hwcb * PAGE_SIZE,
				       BUF_HWCB_TIMES_LOST,
				       BUF_HWCB_MTO_LOST,
				       BUF_HWCB_CHAR_LOST);
	else
		internal_print (
				       DELAYED_WRITE,
				       HWC_RW_PRINT_HEADER
				       "page allocation failed, "
			   "could not expand buffer for output (currently in "
			     "use: %i HWCBs = %li bytes), skipped content of "
			"oldest HWCB %i time(s) (%i lines = %i characters)\n",
				       hwc_data.hwcb_count,
				       hwc_data.hwcb_count * PAGE_SIZE,
				       BUF_HWCB_TIMES_LOST,
				       BUF_HWCB_MTO_LOST,
				       BUF_HWCB_CHAR_LOST);

	return retval;
}

static int 
allocate_write_hwcb (void)
{
	unsigned char *page;
	int page_nr;

	if (hwc_data.hwcb_count == hwc_data.ioctls.max_hwcb)
		return -ENOMEM;

	page_nr = find_first_zero_bit (&hwc_data.kmem_pages, MAX_KMEM_PAGES);
	if (page_nr < hwc_data.ioctls.kmem_hwcb) {

		page = (unsigned char *)
		    (hwc_data.kmem_start + (page_nr << 12));
		set_bit (page_nr, &hwc_data.kmem_pages);
	} else
		page = (unsigned char *) __get_free_page (GFP_ATOMIC | GFP_DMA);

	if (!page)
		return -ENOMEM;

	if (!OUT_HWCB)
		OUT_HWCB = page;
	else
		BUF_HWCB_NEXT = page;

	BUF_HWCB = page;

	BUF_HWCB_NEXT = NULL;

	hwc_data.hwcb_count++;

	prepare_write_hwcb ();

	BUF_HWCB_TIMES_LOST = 0;
	BUF_HWCB_MTO_LOST = 0;
	BUF_HWCB_CHAR_LOST = 0;

#ifdef BUFFER_STRESS_TEST

	internal_print (
			       DELAYED_WRITE,
			       "*** " HWC_RW_PRINT_HEADER
			    "page #%i at 0x%x for buffering allocated. ***\n",
			       hwc_data.hwcb_count, page);

#endif

	return 0;
}

static int 
release_write_hwcb (void)
{
	unsigned long page;
	int page_nr;

	if (!hwc_data.hwcb_count)
		return -ENODATA;

	if (hwc_data.hwcb_count == 1) {

		prepare_write_hwcb ();

		ALL_HWCB_CHAR = 0;
		ALL_HWCB_MTO = 0;
		BUF_HWCB_TIMES_LOST = 0;
		BUF_HWCB_MTO_LOST = 0;
		BUF_HWCB_CHAR_LOST = 0;
	} else {
		page = (unsigned long) OUT_HWCB;

		ALL_HWCB_MTO -= OUT_HWCB_MTO;
		ALL_HWCB_CHAR -= OUT_HWCB_CHAR;
		hwc_data.hwcb_count--;

		OUT_HWCB = OUT_HWCB_NEXT;

		if (page >= hwc_data.kmem_start &&
		    page <= hwc_data.kmem_end) {
			/*memset((void *) page, 0, PAGE_SIZE); */

			page_nr = (int) ((page - hwc_data.kmem_start) >> 12);
			clear_bit (page_nr, &hwc_data.kmem_pages);
		} else
			free_page (page);
#ifdef BUFFER_STRESS_TEST

		internal_print (
				       DELAYED_WRITE,
				       "*** " HWC_RW_PRINT_HEADER
			 "page at 0x%x released, %i pages still in use ***\n",
				       page, hwc_data.hwcb_count);

#endif
	}
	return 0;
}