/*
    amd756.c - Part of lm_sensors, Linux kernel modules for hardware
              monitoring

    Copyright (c) 1999 Merlin Hughes <merlin@merlin.org>

    Shamelessly ripped from i2c-piix4.c:

    Copyright (c) 1998, 1999  Frodo Looijaard <frodol@dds.nl> and
    Philip Edelbrock <phil@netroedge.com>

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that 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., 675 Mass Ave, Cambridge, MA 02139, USA.
*/

/*
   Supports AMD756 and AMD766.
   Note: we assume there can only be one device, with one SMBus interface.
*/

#include <linux/version.h>
#include <linux/module.h>
#include <linux/pci.h>
#include <asm/io.h>
#include <linux/kernel.h>
#include <linux/stddef.h>
#include <linux/sched.h>
#include <linux/ioport.h>
#include <linux/i2c.h>
#define LM_DATE "20011118"
#define LM_VERSION "2.6.2"
#include <linux/init.h>

#ifdef MODULE_LICENSE
MODULE_LICENSE("GPL");
#endif

#ifndef PCI_DEVICE_ID_AMD_756
#define PCI_DEVICE_ID_AMD_756 0x740B
#endif
#ifndef PCI_DEVICE_ID_AMD_766
#define PCI_DEVICE_ID_AMD_766 0x7413
#endif

static int supported[] = {PCI_DEVICE_ID_AMD_756,
                          PCI_DEVICE_ID_AMD_766,
                          0 };

/* AMD756 SMBus address offsets */
#define SMB_ADDR_OFFSET        0xE0
#define SMB_IOSIZE             16
#define SMB_GLOBAL_STATUS      (0x0 + amd756_smba)
#define SMB_GLOBAL_ENABLE      (0x2 + amd756_smba)
#define SMB_HOST_ADDRESS       (0x4 + amd756_smba)
#define SMB_HOST_DATA          (0x6 + amd756_smba)
#define SMB_HOST_COMMAND       (0x8 + amd756_smba)
#define SMB_HOST_BLOCK_DATA    (0x9 + amd756_smba)
#define SMB_HAS_DATA           (0xA + amd756_smba)
#define SMB_HAS_DEVICE_ADDRESS (0xC + amd756_smba)
#define SMB_HAS_HOST_ADDRESS   (0xE + amd756_smba)
#define SMB_SNOOP_ADDRESS      (0xF + amd756_smba)

/* PCI Address Constants */

/* address of I/O space */
#define SMBBA     0x058		/* mh */

/* general configuration */
#define SMBGCFG   0x041		/* mh */

/* silicon revision code */
#define SMBREV    0x008

/* Other settings */
#define MAX_TIMEOUT 100

/* AMD756 constants */
#define AMD756_QUICK        0x00
#define AMD756_BYTE         0x01
#define AMD756_BYTE_DATA    0x02
#define AMD756_WORD_DATA    0x03
#define AMD756_PROCESS_CALL 0x04
#define AMD756_BLOCK_DATA   0x05

/* insmod parameters */

#ifdef MODULE
static
#else
extern
#endif
int __init i2c_amd756_init(void);
static int __init amd756_cleanup(void);
static int amd756_setup(void);
static s32 amd756_access(struct i2c_adapter *adap, u16 addr,
			 unsigned short flags, char read_write,
			 u8 command, int size, union i2c_smbus_data *data);
static void amd756_do_pause(unsigned int amount);
static int amd756_transaction(void);
static void amd756_inc(struct i2c_adapter *adapter);
static void amd756_dec(struct i2c_adapter *adapter);
static u32 amd756_func(struct i2c_adapter *adapter);

#ifdef MODULE
extern int init_module(void);
extern int cleanup_module(void);
#endif				/* MODULE */

static struct i2c_algorithm smbus_algorithm = {
	/* name */ "Non-I2C SMBus adapter",
	/* id */ I2C_ALGO_SMBUS,
	/* master_xfer */ NULL,
	/* smbus_access */ amd756_access,
	/* slave;_send */ NULL,
	/* slave_rcv */ NULL,
	/* algo_control */ NULL,
	/* functionality */ amd756_func,
};

static struct i2c_adapter amd756_adapter = {
	"unset",
	I2C_ALGO_SMBUS | I2C_HW_SMBUS_AMD756,
	&smbus_algorithm,
	NULL,
	amd756_inc,
	amd756_dec,
	NULL,
	NULL,
};

static int __initdata amd756_initialized;
static unsigned short amd756_smba = 0;

/* Detect whether a AMD756 can be found, and initialize it, where necessary.
   Note the differences between kernels with the old PCI BIOS interface and
   newer kernels with the real PCI interface. In compat.h some things are
   defined to make the transition easier. */
int amd756_setup(void)
{
	unsigned char temp;
	int *num = supported;
	struct pci_dev *AMD756_dev = NULL;

	if (pci_present() == 0) {
		printk("i2c-amd756.o: Error: No PCI-bus found!\n");
		return(-ENODEV);
	}

	/* Look for the AMD756, function 3 */
	/* Note: we keep on searching until we have found 'function 3' */
	do {
		if((AMD756_dev = pci_find_device(PCI_VENDOR_ID_AMD,
					      *num, AMD756_dev))) {
			if(PCI_FUNC(AMD756_dev->devfn) != 3)
				continue;
			break;
		}
		num++;
	} while (*num != 0);

	if (AMD756_dev == NULL) {
		printk
		    ("i2c-amd756.o: Error: Can't detect AMD756, function 3!\n");
		return(-ENODEV);
	}


	pci_read_config_byte(AMD756_dev, SMBGCFG, &temp);
	if ((temp & 128) == 0) {
		printk
		  ("i2c-amd756.o: Error: SMBus controller I/O not enabled!\n");
		return(-ENODEV);
	}

	/* Determine the address of the SMBus areas */
	/* Technically it is a dword but... */
	pci_read_config_word(AMD756_dev, SMBBA, &amd756_smba);
	amd756_smba &= 0xff00;
	amd756_smba += SMB_ADDR_OFFSET;

	if (check_region(amd756_smba, SMB_IOSIZE)) {
		printk
		    ("i2c-amd756.o: SMB region 0x%x already in use!\n",
		     amd756_smba);
		return(-ENODEV);
	}

	/* Everything is happy, let's grab the memory and set things up. */
	request_region(amd756_smba, SMB_IOSIZE, "amd756-smbus");

#ifdef DEBUG
	pci_read_config_byte(AMD756_dev, SMBREV, &temp);
	printk("i2c-amd756.o: SMBREV = 0x%X\n", temp);
	printk("i2c-amd756.o: AMD756_smba = 0x%X\n", amd756_smba);
#endif				/* DEBUG */

	return 0;
}

/* 
  SMBUS event = I/O 28-29 bit 11
     see E0 for the status bits and enabled in E2
     
*/

/* Internally used pause function */
void amd756_do_pause(unsigned int amount)
{
	current->state = TASK_INTERRUPTIBLE;
	schedule_timeout(amount);
}

#define GS_ABRT_STS (1 << 0)
#define GS_COL_STS (1 << 1)
#define GS_PRERR_STS (1 << 2)
#define GS_HST_STS (1 << 3)
#define GS_HCYC_STS (1 << 4)
#define GS_TO_STS (1 << 5)
#define GS_SMB_STS (1 << 11)

#define GS_CLEAR_STS (GS_ABRT_STS | GS_COL_STS | GS_PRERR_STS | \
  GS_HCYC_STS | GS_TO_STS )

#define GE_CYC_TYPE_MASK (7)
#define GE_HOST_STC (1 << 3)

int amd756_transaction(void)
{
	int temp;
	int result = 0;
	int timeout = 0;

#ifdef DEBUG
	printk
	    ("i2c-amd756.o: Transaction (pre): GS=%04x, GE=%04x, ADD=%04x, DAT=%04x\n",
	     inw_p(SMB_GLOBAL_STATUS), inw_p(SMB_GLOBAL_ENABLE),
	     inw_p(SMB_HOST_ADDRESS), inb_p(SMB_HOST_DATA));
#endif

	/* Make sure the SMBus host is ready to start transmitting */
	if ((temp = inw_p(SMB_GLOBAL_STATUS)) & (GS_HST_STS | GS_SMB_STS)) {
#ifdef DEBUG
		printk
		    ("i2c-amd756.o: SMBus busy (%04x). Waiting... \n", temp);
#endif
		do {
			amd756_do_pause(1);
			temp = inw_p(SMB_GLOBAL_STATUS);
		} while ((temp & (GS_HST_STS | GS_SMB_STS)) &&
		         (timeout++ < MAX_TIMEOUT));
		/* If the SMBus is still busy, we give up */
		if (timeout >= MAX_TIMEOUT) {
			printk("i2c-amd756.o: Busy wait timeout! (%04x)\n",
			       temp);
			return(-1);
		}
		timeout = 0;
	}

	/* start the transaction by setting the start bit */
	outw_p(inw(SMB_GLOBAL_ENABLE) | GE_HOST_STC, SMB_GLOBAL_ENABLE);

	/* We will always wait for a fraction of a second! */
	do {
		amd756_do_pause(1);
		temp = inw_p(SMB_GLOBAL_STATUS);
	} while ((temp & GS_HST_STS) && (timeout++ < MAX_TIMEOUT));

	/* If the SMBus is still busy, we give up */
	if (timeout >= MAX_TIMEOUT) {
		printk("i2c-amd756.o: Completion timeout!\n");
		return(-1);
	}

	if (temp & GS_PRERR_STS) {
		result = -1;
#ifdef DEBUG
		printk("i2c-amd756.o: SMBus Protocol error (no response)!\n");
#endif
	}

	if (temp & GS_COL_STS) {
		result = -1;
		printk("i2c-amd756.o: SMBus collision!\n");
		/* TODO: Clear Collision Status with a 1 */
	}

	if (temp & GS_TO_STS) {
		result = -1;
#ifdef DEBUG
		printk("i2c-amd756.o: SMBus protocol timeout!\n");
#endif
	}
#ifdef DEBUG
	if (temp & GS_HCYC_STS) {
		printk("i2c-amd756.o: SMBus protocol success!\n");
	}
#endif

	outw_p(GS_CLEAR_STS, SMB_GLOBAL_STATUS);

#ifdef DEBUG
	if (((temp = inw_p(SMB_GLOBAL_STATUS)) & GS_CLEAR_STS) != 0x00) {
		printk
		    ("i2c-amd756.o: Failed reset at end of transaction (%04x)\n",
		     temp);
	}
	printk
	    ("i2c-amd756.o: Transaction (post): GS=%04x, GE=%04x, ADD=%04x, DAT=%04x\n",
	     inw_p(SMB_GLOBAL_STATUS), inw_p(SMB_GLOBAL_ENABLE),
	     inw_p(SMB_HOST_ADDRESS), inb_p(SMB_HOST_DATA));
#endif

	return result;
}

/* Return -1 on error. See smbus.h for more information */
s32 amd756_access(struct i2c_adapter * adap, u16 addr,
		  unsigned short flags, char read_write,
		  u8 command, int size, union i2c_smbus_data * data)
{
	int i, len;

  /** TODO: Should I supporte the 10-bit transfers? */
	switch (size) {
	case I2C_SMBUS_PROC_CALL:
		printk
		    ("i2c-amd756.o: I2C_SMBUS_PROC_CALL not supported!\n");
		/* TODO: Well... It is supported, I'm just not sure what to do here... */
		return -1;
	case I2C_SMBUS_QUICK:
		outw_p(((addr & 0x7f) << 1) | (read_write & 0x01),
		       SMB_HOST_ADDRESS);
		size = AMD756_QUICK;
		break;
	case I2C_SMBUS_BYTE:
		outw_p(((addr & 0x7f) << 1) | (read_write & 0x01),
		       SMB_HOST_ADDRESS);
		/* TODO: Why only during write? */
		if (read_write == I2C_SMBUS_WRITE)
			outb_p(command, SMB_HOST_COMMAND);
		size = AMD756_BYTE;
		break;
	case I2C_SMBUS_BYTE_DATA:
		outw_p(((addr & 0x7f) << 1) | (read_write & 0x01),
		       SMB_HOST_ADDRESS);
		outb_p(command, SMB_HOST_COMMAND);
		if (read_write == I2C_SMBUS_WRITE)
			outw_p(data->byte, SMB_HOST_DATA);
		size = AMD756_BYTE_DATA;
		break;
	case I2C_SMBUS_WORD_DATA:
		outw_p(((addr & 0x7f) << 1) | (read_write & 0x01),
		       SMB_HOST_ADDRESS);
		outb_p(command, SMB_HOST_COMMAND);
		if (read_write == I2C_SMBUS_WRITE)
			outw_p(data->word, SMB_HOST_DATA);	/* TODO: endian???? */
		size = AMD756_WORD_DATA;
		break;
	case I2C_SMBUS_BLOCK_DATA:
		outw_p(((addr & 0x7f) << 1) | (read_write & 0x01),
		       SMB_HOST_ADDRESS);
		outb_p(command, SMB_HOST_COMMAND);
		if (read_write == I2C_SMBUS_WRITE) {
			len = data->block[0];
			if (len < 0)
				len = 0;
			if (len > 32)
				len = 32;
			outw_p(len, SMB_HOST_DATA);
			/* i = inw_p(SMBHSTCNT); Reset SMBBLKDAT */
			for (i = 1; i <= len; i++)
				outb_p(data->block[i],
				       SMB_HOST_BLOCK_DATA);
		}
		size = AMD756_BLOCK_DATA;
		break;
	}

	/* How about enabling interrupts... */
	outw_p(size & GE_CYC_TYPE_MASK, SMB_GLOBAL_ENABLE);

	if (amd756_transaction())	/* Error in transaction */
		return -1;

	if ((read_write == I2C_SMBUS_WRITE) || (size == AMD756_QUICK))
		return 0;


	switch (size) {
	case AMD756_BYTE:
		data->byte = inw_p(SMB_HOST_DATA);
		break;
	case AMD756_BYTE_DATA:
		data->byte = inw_p(SMB_HOST_DATA);
		break;
	case AMD756_WORD_DATA:
		data->word = inw_p(SMB_HOST_DATA);	/* TODO: endian???? */
		break;
	case AMD756_BLOCK_DATA:
		data->block[0] = inw_p(SMB_HOST_DATA & 63);
		/* i = inw_p(SMBHSTCNT); Reset SMBBLKDAT */
		for (i = 1; i <= data->block[0]; i++)
			data->block[i] = inb_p(SMB_HOST_BLOCK_DATA);
		break;
	}

	return 0;
}

void amd756_inc(struct i2c_adapter *adapter)
{
	MOD_INC_USE_COUNT;
}

void amd756_dec(struct i2c_adapter *adapter)
{

	MOD_DEC_USE_COUNT;
}

u32 amd756_func(struct i2c_adapter *adapter)
{
	return I2C_FUNC_SMBUS_QUICK | I2C_FUNC_SMBUS_BYTE |
	    I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_WORD_DATA |
	    I2C_FUNC_SMBUS_BLOCK_DATA | I2C_FUNC_SMBUS_PROC_CALL;
}

int __init i2c_amd756_init(void)
{
	int res;
	printk("i2c-amd756.o version %s (%s)\n", LM_VERSION, LM_DATE);
#ifdef DEBUG
/* PE- It might be good to make this a permanent part of the code! */
	if (amd756_initialized) {
		printk
		    ("i2c-amd756.o: Oops, amd756_init called a second time!\n");
		return -EBUSY;
	}
#endif
	amd756_initialized = 0;
	if ((res = amd756_setup())) {
		printk
		    ("i2c-amd756.o: AMD756/766 not detected, module not inserted.\n");
		amd756_cleanup();
		return res;
	}
	amd756_initialized++;
	sprintf(amd756_adapter.name, "SMBus AMD7X6 adapter at %04x",
		amd756_smba);
	if ((res = i2c_add_adapter(&amd756_adapter))) {
		printk
		    ("i2c-amd756.o: Adapter registration failed, module not inserted.\n");
		amd756_cleanup();
		return res;
	}
	amd756_initialized++;
	printk("i2c-amd756.o: AMD756/766 bus detected and initialized\n");
	return 0;
}

int __init amd756_cleanup(void)
{
	int res;
	if (amd756_initialized >= 2) {
		if ((res = i2c_del_adapter(&amd756_adapter))) {
			printk
			    ("i2c-amd756.o: i2c_del_adapter failed, module not removed\n");
			return res;
		} else
			amd756_initialized--;
	}
	if (amd756_initialized >= 1) {
		release_region(amd756_smba, SMB_IOSIZE);
		amd756_initialized--;
	}
	return 0;
}

EXPORT_NO_SYMBOLS;

#ifdef MODULE

MODULE_AUTHOR("Merlin Hughes <merlin@merlin.org>");
MODULE_DESCRIPTION("AMD756/766 SMBus driver");

int init_module(void)
{
	return i2c_amd756_init();
}

int cleanup_module(void)
{
	return amd756_cleanup();
}

#endif				/* MODULE */
