umem.c

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/*
 * mm.c - Micro Memory(tm) PCI memory board block device driver - v2.3
 *
 * (C) 2001 San Mehat <[e-mail]>
 * (C) 2001 Johannes Erdfelt <[e-mail]>
 * (C) 2001 NeilBrown <[e-mail]>
 *
 * This driver for the Micro Memory PCI Memory Module with Battery Backup
 * is Copyright Micro Memory Inc 2001-2002.  All rights reserved.
 *
 * This driver is released to the public under the terms of the
 *  GNU GENERAL PUBLIC LICENSE version 2
 * See the file COPYING for details.
 *
 * This driver provides a standard block device interface for Micro Memory(tm)
 * PCI based RAM boards.
 * 10/05/01: Phap Nguyen - Rebuilt the driver
 * 10/22/01: Phap Nguyen - v2.1 Added disk partitioning
 * 29oct2001:NeilBrown   - Use make_request_fn instead of request_fn
 *                       - use stand disk partitioning (so fdisk works).
 * 08nov2001:NeilBrown	 - change driver name from "mm" to "umem"
 *			 - incorporate into main kernel
 * 08apr2002:NeilBrown   - Move some of interrupt handle to tasklet
 *			 - use spin_lock_bh instead of _irq
 *			 - Never block on make_request.  queue
 *			   bh's instead.
 *			 - unregister umem from devfs at mod unload
 *			 - Change version to 2.3
 * 07Nov2001:Phap Nguyen - Select pci read command: 06, 12, 15 (Decimal)
 * 07Jan2002: P. Nguyen  - Used PCI Memory Write & Invalidate for DMA
 * 15May2002:NeilBrown   - convert to bio for 2.5
 * 17May2002:NeilBrown   - remove init_mem initialisation.  Instead detect
 *			 - a sequence of writes that cover the card, and
 *			 - set initialised bit then.
 */

#undef DEBUG	/* #define DEBUG if you want debugging info (pr_debug) */
#include <linux/fs.h>
#include <linux/bio.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/mman.h>
#include <linux/ioctl.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/timer.h>
#include <linux/pci.h>
#include <linux/slab.h>
#include <linux/dma-mapping.h>

#include <linux/fcntl.h>        /* O_ACCMODE */
#include <linux/hdreg.h>  /* HDIO_GETGEO */

#include "umem.h"

#include <asm/uaccess.h>
#include <asm/io.h>

#define MM_MAXCARDS 4
#define MM_RAHEAD 2      /* two sectors */
#define MM_BLKSIZE 1024  /* 1k blocks */
#define MM_HARDSECT 512  /* 512-byte hardware sectors */
#define MM_SHIFT 6       /* max 64 partitions on 4 cards  */

/*
 * Version Information
 */

#define DRIVER_NAME	"umem"
#define DRIVER_VERSION	"v2.3"
#define DRIVER_AUTHOR	"San Mehat, Johannes Erdfelt, NeilBrown"
#define DRIVER_DESC	"Micro Memory(tm) PCI memory board block driver"

static int debug;
/* #define HW_TRACE(x)     writeb(x,cards[0].csr_remap + MEMCTRLSTATUS_MAGIC) */
#define HW_TRACE(x)

#define DEBUG_LED_ON_TRANSFER	0x01
#define DEBUG_BATTERY_POLLING	0x02

module_param(debug, int, 0644);
MODULE_PARM_DESC(debug, "Debug bitmask");

static int pci_read_cmd = 0x0C;		/* Read Multiple */
module_param(pci_read_cmd, int, 0);
MODULE_PARM_DESC(pci_read_cmd, "PCI read command");

static int pci_write_cmd = 0x0F;	/* Write and Invalidate */
module_param(pci_write_cmd, int, 0);
MODULE_PARM_DESC(pci_write_cmd, "PCI write command");

static int pci_cmds;

static int major_nr;

#include <linux/blkdev.h>
#include <linux/blkpg.h>

struct cardinfo {
	struct pci_dev	*dev;

	unsigned char	__iomem *csr_remap;
	unsigned int	mm_size;  /* size in kbytes */

	unsigned int	init_size; /* initial segment, in sectors,
				    * that we know to
				    * have been written
				    */
	struct bio	*bio, *currentbio, **biotail;
	int		current_idx;
	sector_t	current_sector;

	struct request_queue *queue;

	struct mm_page {
		dma_addr_t		page_dma;
		struct mm_dma_desc	*desc;
		int	 		cnt, headcnt;
		struct bio		*bio, **biotail;
		int			idx;
	} mm_pages[2];
#define DESC_PER_PAGE ((PAGE_SIZE*2)/sizeof(struct mm_dma_desc))

	int  Active, Ready;

	struct tasklet_struct	tasklet;
	unsigned int dma_status;

	struct {
		int		good;
		int		warned;
		unsigned long	last_change;
	} battery[2];

	spinlock_t 	lock;
	int		check_batteries;

	int		flags;
};

static struct cardinfo cards[MM_MAXCARDS];
static struct block_device_operations mm_fops;
static struct timer_list battery_timer;

static int num_cards;

static struct gendisk *mm_gendisk[MM_MAXCARDS];

static void check_batteries(struct cardinfo *card);

static int get_userbit(struct cardinfo *card, int bit)
{
	unsigned char led;

	led = readb(card->csr_remap + MEMCTRLCMD_LEDCTRL);
	return led & bit;
}

static int set_userbit(struct cardinfo *card, int bit, unsigned char state)
{
	unsigned char led;

	led = readb(card->csr_remap + MEMCTRLCMD_LEDCTRL);
	if (state)
		led |= bit;
	else
		led &= ~bit;
	writeb(led, card->csr_remap + MEMCTRLCMD_LEDCTRL);

	return 0;
}

/*
 * NOTE: For the power LED, use the LED_POWER_* macros since they differ
 */
static void set_led(struct cardinfo *card, int shift, unsigned char state)
{
	unsigned char led;

	led = readb(card->csr_remap + MEMCTRLCMD_LEDCTRL);
	if (state == LED_FLIP)
		led ^= (1<<shift);
	else {
		led &= ~(0x03 << shift);
		led |= (state << shift);
	}
	writeb(led, card->csr_remap + MEMCTRLCMD_LEDCTRL);

}

#ifdef MM_DIAG
static void dump_regs(struct cardinfo *card)
{
	unsigned char *p;
	int i, i1;

	p = card->csr_remap;
	for (i = 0; i < 8; i++) {
		printk(KERN_DEBUG "%p   ", p);

		for (i1 = 0; i1 < 16; i1++)
			printk("%02x ", *p++);

		printk("\n");
	}
}
#endif

static void dump_dmastat(struct cardinfo *card, unsigned int dmastat)
{
	dev_printk(KERN_DEBUG, &card->dev->dev, "DMAstat - ");
	if (dmastat & DMASCR_ANY_ERR)
		printk(KERN_CONT "ANY_ERR ");
	if (dmastat & DMASCR_MBE_ERR)
		printk(KERN_CONT "MBE_ERR ");
	if (dmastat & DMASCR_PARITY_ERR_REP)
		printk(KERN_CONT "PARITY_ERR_REP ");
	if (dmastat & DMASCR_PARITY_ERR_DET)
		printk(KERN_CONT "PARITY_ERR_DET ");
	if (dmastat & DMASCR_SYSTEM_ERR_SIG)
		printk(KERN_CONT "SYSTEM_ERR_SIG ");
	if (dmastat & DMASCR_TARGET_ABT)
		printk(KERN_CONT "TARGET_ABT ");
	if (dmastat & DMASCR_MASTER_ABT)
		printk(KERN_CONT "MASTER_ABT ");
	if (dmastat & DMASCR_CHAIN_COMPLETE)
		printk(KERN_CONT "CHAIN_COMPLETE ");
	if (dmastat & DMASCR_DMA_COMPLETE)
		printk(KERN_CONT "DMA_COMPLETE ");
	printk("\n");
}

/*
 * Theory of request handling
 *
 * Each bio is assigned to one mm_dma_desc - which may not be enough FIXME
 * We have two pages of mm_dma_desc, holding about 64 descriptors
 * each.  These are allocated at init time.
 * One page is "Ready" and is either full, or can have request added.
 * The other page might be "Active", which DMA is happening on it.
 *
 * Whenever IO on the active page completes, the Ready page is activated
 * and the ex-Active page is clean out and made Ready.
 * Otherwise the Ready page is only activated when it becomes full, or
 * when mm_unplug_device is called via the unplug_io_fn.
 *
 * If a request arrives while both pages a full, it is queued, and b_rdev is
 * overloaded to record whether it was a read or a write.
 *
 * The interrupt handler only polls the device to clear the interrupt.
 * The processing of the result is done in a tasklet.
 */

static void mm_start_io(struct cardinfo *card)
{
	/* we have the lock, we know there is
	 * no IO active, and we know that card->Active
	 * is set
	 */
	struct mm_dma_desc *desc;
	struct mm_page *page;
	int offset;

	/* make the last descriptor end the chain */
	page = &card->mm_pages[card->Active];
	pr_debug("start_io: %d %d->%d\n",
		card->Active, page->headcnt, page->cnt - 1);
	desc = &page->desc[page->cnt-1];

	desc->control_bits |= cpu_to_le32(DMASCR_CHAIN_COMP_EN);
	desc->control_bits &= ~cpu_to_le32(DMASCR_CHAIN_EN);
	desc->sem_control_bits = desc->control_bits;


	if (debug & DEBUG_LED_ON_TRANSFER)
		set_led(card, LED_REMOVE, LED_ON);

	desc = &page->desc[page->headcnt];
	writel(0, card->csr_remap + DMA_PCI_ADDR);
	writel(0, card->csr_remap + DMA_PCI_ADDR + 4);

	writel(0, card->csr_remap + DMA_LOCAL_ADDR);
	writel(0, card->csr_remap + DMA_LOCAL_ADDR + 4);

	writel(0, card->csr_remap + DMA_TRANSFER_SIZE);
	writel(0, card->csr_remap + DMA_TRANSFER_SIZE + 4);

	writel(0, card->csr_remap + DMA_SEMAPHORE_ADDR);
	writel(0, card->csr_remap + DMA_SEMAPHORE_ADDR + 4);

	offset = ((char *)desc) - ((char *)page->desc);
	writel(cpu_to_le32((page->page_dma+offset) & 0xffffffff),
	       card->csr_remap + DMA_DESCRIPTOR_ADDR);
	/* Force the value to u64 before shifting otherwise >> 32 is undefined C
	 * and on some ports will do nothing ! */
	writel(cpu_to_le32(((u64)page->page_dma)>>32),
	       card->csr_remap + DMA_DESCRIPTOR_ADDR + 4);

	/* Go, go, go */
	writel(cpu_to_le32(DMASCR_GO | DMASCR_CHAIN_EN | pci_cmds),
	       card->csr_remap + DMA_STATUS_CTRL);
}

static int add_bio(struct cardinfo *card);

static void activate(struct cardinfo *card)
{
	/* if No page is Active, and Ready is
	 * not empty, then switch Ready page
	 * to active and start IO.
	 * Then add any bh's that are available to Ready
	 */

	do {
		while (add_bio(card))
			;

		if (card->Active == -1 &&
		    card->mm_pages[card->Ready].cnt > 0) {
			card->Active = card->Ready;
			card->Ready = 1-card->Ready;
			mm_start_io(card);
		}

	} while (card->Active == -1 && add_bio(card));
}

static inline void reset_page(struct mm_page *page)
{
	page->cnt = 0;
	page->headcnt = 0;
	page->bio = NULL;
	page->biotail = &page->bio;
}

static void mm_unplug_device(struct request_queue *q)
{
	struct cardinfo *card = q->queuedata;
	unsigned long flags;

	spin_lock_irqsave(&card->lock, flags);
	if (blk_remove_plug(q))
		activate(card);
	spin_unlock_irqrestore(&card->lock, flags);
}

/*
 * If there is room on Ready page, take
 * one bh off list and add it.
 * return 1 if there was room, else 0.
 */
static int add_bio(struct cardinfo *card)
{
	struct mm_page *p;
	struct mm_dma_desc *desc;
	dma_addr_t dma_handle;
	int offset;
	struct bio *bio;
	struct bio_vec *vec;
	int idx;
	int rw;
	int len;

	bio = card->currentbio;
	if (!bio && card->bio) {
		card->currentbio = card->bio;
		card->current_idx = card->bio->bi_idx;
		card->current_sector = card->bio->bi_sector;
		card->bio = card->bio->bi_next;
		if (card->bio == NULL)
			card->biotail = &card->bio;
		card->currentbio->bi_next = NULL;
		return 1;
	}
	if (!bio)
		return 0;
	idx = card->current_idx;

	rw = bio_rw(bio);
	if (card->mm_pages[card->Ready].cnt >= DESC_PER_PAGE)
		return 0;