path: root/drivers/sn/ioc3.c

/*
 * SGI IOC3 master driver and IRQ demuxer
 *
 * Copyright (c) 2005 Stanislaw Skowronek <skylark@linux-mips.org>
 * Heavily based on similar work by:
 *   Brent Casavant <bcasavan@sgi.com> - IOC4 master driver
 *   Pat Gefre <pfg@sgi.com> - IOC3 serial port IRQ demuxer
 */

#include <linux/errno.h>
#include <linux/module.h>
#include <linux/pci.h>
#include <linux/dma-mapping.h>
#include <linux/interrupt.h>
#include <linux/spinlock.h>
#include <linux/delay.h>
#include <linux/ioc3.h>
#include <linux/rwsem.h>

#define IOC3_PCI_SIZE 0x100000

static LIST_HEAD(ioc3_devices);
static int ioc3_counter;
static DECLARE_RWSEM(ioc3_devices_rwsem);

static struct ioc3_submodule *ioc3_submodules[IOC3_MAX_SUBMODULES];
static struct ioc3_submodule *ioc3_ethernet;
static DEFINE_RWLOCK(ioc3_submodules_lock);

/* NIC probing code */

#define GPCR_MLAN_EN    0x00200000      /* enable MCR to pin 8 */

static inline unsigned mcr_pack(unsigned pulse, unsigned sample)
{
	return (pulse << 10) | (sample << 2);
}

static int nic_wait(struct ioc3_driver_data *idd)
{
	unsigned mcr;

        do {
                mcr = readl(&idd->vma->mcr);
        } while (!(mcr & 2));

        return mcr & 1;
}

static int nic_reset(struct ioc3_driver_data *idd)
{
        int presence;
	unsigned long flags;

	local_irq_save(flags);
	writel(mcr_pack(500, 65), &idd->vma->mcr);
	presence = nic_wait(idd);
	local_irq_restore(flags);

	udelay(500);

        return presence;
}

static int nic_read_bit(struct ioc3_driver_data *idd)
{
	int result;
	unsigned long flags;

	local_irq_save(flags);
	writel(mcr_pack(6, 13), &idd->vma->mcr);
	result = nic_wait(idd);
	local_irq_restore(flags);

	udelay(500);

	return result;
}

static void nic_write_bit(struct ioc3_driver_data *idd, int bit)
{
	if (bit)
		writel(mcr_pack(6, 110), &idd->vma->mcr);
	else
		writel(mcr_pack(80, 30), &idd->vma->mcr);

	nic_wait(idd);
}

static unsigned nic_read_byte(struct ioc3_driver_data *idd)
{
	unsigned result = 0;
	int i;

	for (i = 0; i < 8; i++)
		result = (result >> 1) | (nic_read_bit(idd) << 7);

	return result;
}

static void nic_write_byte(struct ioc3_driver_data *idd, int byte)
{
	int i, bit;

	for (i = 8; i; i--) {
		bit = byte & 1;
		byte >>= 1;

		nic_write_bit(idd, bit);
	}
}

static unsigned long
nic_find(struct ioc3_driver_data *idd, int *last, unsigned long addr)
{
	int a, b, index, disc;

	nic_reset(idd);

	/* Search ROM.  */
	nic_write_byte(idd, 0xF0);

	/* Algorithm from ``Book of iButton Standards''.  */
	for (index = 0, disc = 0; index < 64; index++) {
		a = nic_read_bit(idd);
		b = nic_read_bit(idd);

		if (a && b) {
			printk(KERN_WARNING "IOC3 NIC search failed.\n");
			*last = 0;
			return 0;
		}

		if (!a && !b) {
			if (index == *last) {
				addr |= 1UL << index;
			} else if (index > *last) {
				addr &= ~(1UL << index);
				disc = index;
			} else if ((addr & (1UL << index)) == 0)
				disc = index;
			nic_write_bit(idd, (addr>>index)&1);
			continue;
		} else {
			if (a)
				addr |= 1UL << index;
			else
				addr &= ~(1UL << index);
			nic_write_bit(idd, a);
			continue;
		}
	}
	*last = disc;
	return addr;
}

static void nic_addr(struct ioc3_driver_data *idd, unsigned long addr)
{
	int index;

	nic_reset(idd);
	nic_write_byte(idd, 0xF0);
	for (index = 0; index < 64; index++) {
		nic_read_bit(idd);
		nic_read_bit(idd);
		nic_write_bit(idd, (addr>>index)&1);
	}
}

static void crc16_byte(unsigned int *crc, unsigned char db)
{
	int i;

	for(i=0;i<8;i++) {
		*crc <<= 1;
		if((db^(*crc>>16)) & 1)
			*crc ^= 0x8005;
		db >>= 1;
	}
	*crc &= 0xFFFF;