/* Linux driver for Disk-On-Chip devices			*/
/* Probe routines common to all DoC devices			*/
/* (c) 1999 Machine Vision Holdings, Inc.			*/
/* Author: David Woodhouse <dwmw2@infradead.org>		*/
/* $Id: docprobe.c,v 1.30 2001/10/02 15:05:13 dwmw2 Exp $	*/



/* DOC_PASSIVE_PROBE:
   In order to ensure that the BIOS checksum is correct at boot time, and 
   hence that the onboard BIOS extension gets executed, the DiskOnChip 
   goes into reset mode when it is read sequentially: all registers 
   return 0xff until the chip is woken up again by writing to the 
   DOCControl register. 

   Unfortunately, this means that the probe for the DiskOnChip is unsafe, 
   because one of the first things it does is write to where it thinks 
   the DOCControl register should be - which may well be shared memory 
   for another device. I've had machines which lock up when this is 
   attempted. Hence the possibility to do a passive probe, which will fail 
   to detect a chip in reset mode, but is at least guaranteed not to lock
   the machine.

   If you have this problem, uncomment the following line:
#define DOC_PASSIVE_PROBE
*/


/* DOC_SINGLE_DRIVER:
   Millennium driver has been merged into DOC2000 driver.

   The newly-merged driver doesn't appear to work for writing. It's the
   same with the DiskOnChip 2000 and the Millennium. If you have a 
   Millennium and you want write support to work, remove the definition
   of DOC_SINGLE_DRIVER below to use the old doc2001-specific driver.

   Otherwise, it's left on in the hope that it'll annoy someone with
   a Millennium enough that they go through and work out what the 
   difference is :)
*/
#define DOC_SINGLE_DRIVER

#include <linux/config.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <asm/errno.h>
#include <asm/io.h>
#include <asm/uaccess.h>
#include <linux/miscdevice.h>
#include <linux/pci.h>
#include <linux/delay.h>
#include <linux/slab.h>
#include <linux/sched.h>
#include <linux/init.h>
#include <linux/types.h>

#include <linux/mtd/mtd.h>
#include <linux/mtd/nand.h>
#include <linux/mtd/doc2000.h>

/* Where to look for the devices? */
#ifndef CONFIG_MTD_DOCPROBE_ADDRESS
#define CONFIG_MTD_DOCPROBE_ADDRESS 0
#endif


static unsigned long doc_config_location = CONFIG_MTD_DOCPROBE_ADDRESS;
MODULE_PARM(doc_config_location, "l");


static unsigned long __initdata doc_locations[] = {
#if defined (__alpha__) || defined(__i386__) || defined(__x86_64__)
#ifdef CONFIG_MTD_DOCPROBE_HIGH
	0xfffc8000, 0xfffca000, 0xfffcc000, 0xfffce000, 
	0xfffd0000, 0xfffd2000, 0xfffd4000, 0xfffd6000,
	0xfffd8000, 0xfffda000, 0xfffdc000, 0xfffde000, 
	0xfffe0000, 0xfffe2000, 0xfffe4000, 0xfffe6000, 
	0xfffe8000, 0xfffea000, 0xfffec000, 0xfffee000,
#else /*  CONFIG_MTD_DOCPROBE_HIGH */
	0xc8000, 0xca000, 0xcc000, 0xce000, 
	0xd0000, 0xd2000, 0xd4000, 0xd6000,
	0xd8000, 0xda000, 0xdc000, 0xde000, 
	0xe0000, 0xe2000, 0xe4000, 0xe6000, 
	0xe8000, 0xea000, 0xec000, 0xee000,
#endif /*  CONFIG_MTD_DOCPROBE_HIGH */
#elif defined(__ppc__)
	0xe4000000,
#elif defined(CONFIG_MOMENCO_OCELOT)
	0x2f000000,
#else
#warning Unknown architecture for DiskOnChip. No default probe locations defined
#endif
	0 };

/* doccheck: Probe a given memory window to see if there's a DiskOnChip present */

static inline int __init doccheck(unsigned long potential, unsigned long physadr)
{
	unsigned long window=potential;
	unsigned char tmp, ChipID;
#ifndef DOC_PASSIVE_PROBE
	unsigned char tmp2;
#endif

	/* Routine copied from the Linux DOC driver */

#ifdef CONFIG_MTD_DOCPROBE_55AA
	/* Check for 0x55 0xAA signature at beginning of window,
	   this is no longer true once we remove the IPL (for Millennium */
	if (ReadDOC(window, Sig1) != 0x55 || ReadDOC(window, Sig2) != 0xaa)
		return 0;
#endif /* CONFIG_MTD_DOCPROBE_55AA */

#ifndef DOC_PASSIVE_PROBE	
	/* It's not possible to cleanly detect the DiskOnChip - the
	 * bootup procedure will put the device into reset mode, and
	 * it's not possible to talk to it without actually writing
	 * to the DOCControl register. So we store the current contents
	 * of the DOCControl register's location, in case we later decide
	 * that it's not a DiskOnChip, and want to put it back how we
	 * found it. 
	 */
	tmp2 = ReadDOC(window, DOCControl);
	
	/* Reset the DiskOnChip ASIC */
	WriteDOC(DOC_MODE_CLR_ERR | DOC_MODE_MDWREN | DOC_MODE_RESET, 
		 window, DOCControl);
	WriteDOC(DOC_MODE_CLR_ERR | DOC_MODE_MDWREN | DOC_MODE_RESET, 
		 window, DOCControl);
	
	/* Enable the DiskOnChip ASIC */
	WriteDOC(DOC_MODE_CLR_ERR | DOC_MODE_MDWREN | DOC_MODE_NORMAL, 
		 window, DOCControl);
	WriteDOC(DOC_MODE_CLR_ERR | DOC_MODE_MDWREN | DOC_MODE_NORMAL, 
		 window, DOCControl);
#endif /* !DOC_PASSIVE_PROBE */	

	ChipID = ReadDOC(window, ChipID);
  
	switch (ChipID) {
	case DOC_ChipID_Doc2k:
		/* Check the TOGGLE bit in the ECC register */
		tmp = ReadDOC(window, 2k_ECCStatus) & DOC_TOGGLE_BIT;
		if ((ReadDOC(window, 2k_ECCStatus) & DOC_TOGGLE_BIT) != tmp)
				return ChipID;
		break;
		
	case DOC_ChipID_DocMil:
		/* Check the TOGGLE bit in the ECC register */
		tmp = ReadDOC(window, ECCConf) & DOC_TOGGLE_BIT;
		if ((ReadDOC(window, ECCConf) & DOC_TOGGLE_BIT) != tmp)
				return ChipID;
		break;
		
	default:
#ifndef CONFIG_MTD_DOCPROBE_55AA
		printk(KERN_WARNING "Possible DiskOnChip with unknown ChipID %2.2X found at 0x%lx\n",
		       ChipID, physadr);
#endif
#ifndef DOC_PASSIVE_PROBE
		/* Put back the contents of the DOCControl register, in case it's not
		 * actually a DiskOnChip.
		 */
		WriteDOC(tmp2, window, DOCControl);
#endif
		return 0;
	}

	printk(KERN_WARNING "DiskOnChip failed TOGGLE test, dropping.\n");

#ifndef DOC_PASSIVE_PROBE
	/* Put back the contents of the DOCControl register: it's not a DiskOnChip */
	WriteDOC(tmp2, window, DOCControl);
#endif
	return 0;
}   

static int docfound;

static void __init DoC_Probe(unsigned long physadr)
{
	unsigned long docptr;
	struct DiskOnChip *this;
	struct mtd_info *mtd;
	int ChipID;
	char namebuf[15];
	char *name = namebuf;
	char *im_funcname = NULL;
	char *im_modname = NULL;
	void (*initroutine)(struct mtd_info *) = NULL;

	docptr = (unsigned long)ioremap(physadr, DOC_IOREMAP_LEN);
	
	if (!docptr)
		return;
	
	if ((ChipID = doccheck(docptr, physadr))) {
		docfound = 1;
		mtd = kmalloc(sizeof(struct DiskOnChip) + sizeof(struct mtd_info), GFP_KERNEL);

		if (!mtd) {
			printk(KERN_WARNING "Cannot allocate memory for data structures. Dropping.\n");
			iounmap((void *)docptr);
			return;
		}
		
		this = (struct DiskOnChip *)(&mtd[1]);
		
		memset((char *)mtd,0, sizeof(struct mtd_info));
		memset((char *)this, 0, sizeof(struct DiskOnChip));

		mtd->priv = this;
		this->virtadr = docptr;
		this->physadr = physadr;
		this->ChipID = ChipID;
		sprintf(namebuf, "with ChipID %2.2X", ChipID);

		switch(ChipID) {
		case DOC_ChipID_Doc2k:
			name="2000";
			im_funcname = "DoC2k_init";
			im_modname = "doc2000";
			break;
			
		case DOC_ChipID_DocMil:
			name="Millennium";
#ifdef DOC_SINGLE_DRIVER
			im_funcname = "DoC2k_init";
			im_modname = "doc2000";
#else
			im_funcname = "DoCMil_init";
			im_modname = "doc2001";
#endif /* DOC_SINGLE_DRIVER */
			break;
		}

		if (im_funcname)
			initroutine = inter_module_get_request(im_funcname, im_modname);

		if (initroutine) {
			(*initroutine)(mtd);
			inter_module_put(im_funcname);
			return;
		}
		printk(KERN_NOTICE "Cannot find driver for DiskOnChip %s at 0x%lX\n", name, physadr);
	}
	iounmap((void *)docptr);
}


/****************************************************************************
 *
 * Module stuff
 *
 ****************************************************************************/

int __init init_doc(void)
{
	int i;
	
	if (doc_config_location) {
		printk(KERN_INFO "Using configured DiskOnChip probe address 0x%lx\n", doc_config_location);
		DoC_Probe(doc_config_location);
	} else {
		for (i=0; doc_locations[i]; i++) {
			DoC_Probe(doc_locations[i]);
		}
	}
	/* No banner message any more. Print a message if no DiskOnChip
	   found, so the user knows we at least tried. */
	if (!docfound)
		printk(KERN_INFO "No recognised DiskOnChip devices found\n");
	/* So it looks like we've been used and we get unloaded */
	MOD_INC_USE_COUNT;
	MOD_DEC_USE_COUNT;
	return 0;
	
}

module_init(init_doc);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
MODULE_DESCRIPTION("Probe code for DiskOnChip 2000 and Millennium devices");