scx200_acb.c
// SPDX-License-Identifier: GPL-2.0-or-later
/*
Copyright (c) 2001,2002 Christer Weinigel <wingel@nano-system.com>
National Semiconductor SCx200 ACCESS.bus support
Also supports the AMD CS5535 and AMD CS5536
Based on i2c-keywest.c which is:
Copyright (c) 2001 Benjamin Herrenschmidt <benh@kernel.crashing.org>
Copyright (c) 2000 Philip Edelbrock <phil@stimpy.netroedge.com>
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/i2c.h>
#include <linux/pci.h>
#include <linux/platform_device.h>
#include <linux/delay.h>
#include <linux/mutex.h>
#include <linux/slab.h>
#include <linux/io.h>
#include <linux/scx200.h>
MODULE_AUTHOR("Christer Weinigel <wingel@nano-system.com>");
MODULE_DESCRIPTION("NatSemi SCx200 ACCESS.bus Driver");
MODULE_ALIAS("platform:cs5535-smb");
MODULE_LICENSE("GPL");
#define MAX_DEVICES 4
static int base[MAX_DEVICES] = { 0x820, 0x840 };
module_param_hw_array(base, int, ioport, NULL, 0);
MODULE_PARM_DESC(base, "Base addresses for the ACCESS.bus controllers");
#define POLL_TIMEOUT (HZ/5)
enum scx200_acb_state {
state_idle,
state_address,
state_command,
state_repeat_start,
state_quick,
state_read,
state_write,
};
static const char *scx200_acb_state_name[] = {
"idle",
"address",
"command",
"repeat_start",
"quick",
"read",
"write",
};
/* Physical interface */
struct scx200_acb_iface {
struct scx200_acb_iface *next;
struct i2c_adapter adapter;
unsigned base;
struct mutex mutex;
/* State machine data */
enum scx200_acb_state state;
int result;
u8 address_byte;
u8 command;
u8 *ptr;
char needs_reset;
unsigned len;
};
/* Register Definitions */
#define ACBSDA (iface->base + 0)
#define ACBST (iface->base + 1)
#define ACBST_SDAST 0x40 /* SDA Status */
#define ACBST_BER 0x20
#define ACBST_NEGACK 0x10 /* Negative Acknowledge */
#define ACBST_STASTR 0x08 /* Stall After Start */
#define ACBST_MASTER 0x02
#define ACBCST (iface->base + 2)
#define ACBCST_BB 0x02
#define ACBCTL1 (iface->base + 3)
#define ACBCTL1_STASTRE 0x80
#define ACBCTL1_NMINTE 0x40
#define ACBCTL1_ACK 0x10
#define ACBCTL1_STOP 0x02
#define ACBCTL1_START 0x01
#define ACBADDR (iface->base + 4)
#define ACBCTL2 (iface->base + 5)
#define ACBCTL2_ENABLE 0x01
/************************************************************************/
static void scx200_acb_machine(struct scx200_acb_iface *iface, u8 status)
{
const char *errmsg;
dev_dbg(&iface->adapter.dev, "state %s, status = 0x%02x\n",
scx200_acb_state_name[iface->state], status);
if (status & ACBST_BER) {
errmsg = "bus error";
goto error;
}
if (!(status & ACBST_MASTER)) {
errmsg = "not master";
goto error;
}
if (status & ACBST_NEGACK) {
dev_dbg(&iface->adapter.dev, "negative ack in state %s\n",
scx200_acb_state_name[iface->state]);
iface->state = state_idle;
iface->result = -ENXIO;
outb(inb(ACBCTL1) | ACBCTL1_STOP, ACBCTL1);
outb(ACBST_STASTR | ACBST_NEGACK, ACBST);
/* Reset the status register */
outb(0, ACBST);
return;
}
switch (iface->state) {
case state_idle:
dev_warn(&iface->adapter.dev, "interrupt in idle state\n");
break;
case state_address:
/* Do a pointer write first */
outb(iface->address_byte & ~1, ACBSDA);
iface->state = state_command;
break;
case state_command:
outb(iface->command, ACBSDA);
if (iface->address_byte & 1)
iface->state = state_repeat_start;
else
iface->state = state_write;
break;
case state_repeat_start:
outb(inb(ACBCTL1) | ACBCTL1_START, ACBCTL1);
fallthrough;
case state_quick:
if (iface->address_byte & 1) {
if (iface->len == 1)
outb(inb(ACBCTL1) | ACBCTL1_ACK, ACBCTL1);
else
outb(inb(ACBCTL1) & ~ACBCTL1_ACK, ACBCTL1);
outb(iface->address_byte, ACBSDA);
iface->state = state_read;
} else {
outb(iface->address_byte, ACBSDA);
iface->state = state_write;
}
break;
case state_read:
/* Set ACK if _next_ byte will be the last one */
if (iface->len == 2)
outb(inb(ACBCTL1) | ACBCTL1_ACK, ACBCTL1);
else
outb(inb(ACBCTL1) & ~ACBCTL1_ACK, ACBCTL1);
if (iface->len == 1) {
iface->result = 0;
iface->state = state_idle;
outb(inb(ACBCTL1) | ACBCTL1_STOP, ACBCTL1);
}
*iface->ptr++ = inb(ACBSDA);
--iface->len;
break;
case state_write:
if (iface->len == 0) {
iface->result = 0;
iface->state = state_idle;
outb(inb(ACBCTL1) | ACBCTL1_STOP, ACBCTL1);
break;
}
outb(*iface->ptr++, ACBSDA);
--iface->len;
break;
}
return;
error:
dev_err(&iface->adapter.dev,
"%s in state %s (addr=0x%02x, len=%d, status=0x%02x)\n", errmsg,
scx200_acb_state_name[iface->state], iface->address_byte,
iface->len, status);
iface->state = state_idle;
iface->result = -EIO;
iface->needs_reset = 1;
}
static void scx200_acb_poll(struct scx200_acb_iface *iface)
{
u8 status;
unsigned long timeout;
timeout = jiffies + POLL_TIMEOUT;
while (1) {
status = inb(ACBST);
/* Reset the status register to avoid the hang */
outb(0, ACBST);
if ((status & (ACBST_SDAST|ACBST_BER|ACBST_NEGACK)) != 0) {
scx200_acb_machine(iface, status);
return;
}
if (time_after(jiffies, timeout))
break;
cpu_relax();
cond_resched();
}
dev_err(&iface->adapter.dev, "timeout in state %s\n",
scx200_acb_state_name[iface->state]);
iface->state = state_idle;
iface->result = -EIO;
iface->needs_reset = 1;
}
static void scx200_acb_reset(struct scx200_acb_iface *iface)
{
/* Disable the ACCESS.bus device and Configure the SCL
frequency: 16 clock cycles */
outb(0x70, ACBCTL2);
/* Polling mode */
outb(0, ACBCTL1);
/* Disable slave address */
outb(0, ACBADDR);
/* Enable the ACCESS.bus device */
outb(inb(ACBCTL2) | ACBCTL2_ENABLE, ACBCTL2);
/* Free STALL after START */
outb(inb(ACBCTL1) & ~(ACBCTL1_STASTRE | ACBCTL1_NMINTE), ACBCTL1);
/* Send a STOP */
outb(inb(ACBCTL1) | ACBCTL1_STOP, ACBCTL1);
/* Clear BER, NEGACK and STASTR bits */
outb(ACBST_BER | ACBST_NEGACK | ACBST_STASTR, ACBST);
/* Clear BB bit */
outb(inb(ACBCST) | ACBCST_BB, ACBCST);
}
static s32 scx200_acb_smbus_xfer(struct i2c_adapter *adapter,
u16 address, unsigned short flags,
char rw, u8 command, int size,
union i2c_smbus_data *data)
{
struct scx200_acb_iface *iface = i2c_get_adapdata(adapter);
int len;
u8 *buffer;
u16 cur_word;
int rc;
switch (size) {
case I2C_SMBUS_QUICK:
len = 0;
buffer = NULL;
break;
case I2C_SMBUS_BYTE:
len = 1;
buffer = rw ? &data->byte : &command;
break;
case I2C_SMBUS_BYTE_DATA:
len = 1;
buffer = &data->byte;
break;
case I2C_SMBUS_WORD_DATA:
len = 2;
cur_word = cpu_to_le16(data->word);
buffer = (u8 *)&cur_word;
break;
case I2C_SMBUS_I2C_BLOCK_DATA:
len = data->block[0];
if (len == 0 || len > I2C_SMBUS_BLOCK_MAX)
return -EINVAL;
buffer = &data->block[1];
break;
default:
return -EINVAL;
}
dev_dbg(&adapter->dev,
"size=%d, address=0x%x, command=0x%x, len=%d, read=%d\n",
size, address, command, len, rw);
if (!len && rw == I2C_SMBUS_READ) {
dev_dbg(&adapter->dev, "zero length read\n");
return -EINVAL;
}
mutex_lock(&iface->mutex);
iface->address_byte = (address << 1) | rw;
iface->command = command;
iface->ptr = buffer;
iface->len = len;
iface->result = -EINVAL;
iface->needs_reset = 0;
outb(inb(ACBCTL1) | ACBCTL1_START, ACBCTL1);
if (size == I2C_SMBUS_QUICK || size == I2C_SMBUS_BYTE)
iface->state = state_quick;
else
iface->state = state_address;
while (iface->state != state_idle)
scx200_acb_poll(iface);
if (iface->needs_reset)
scx200_acb_reset(iface);
rc = iface->result;
mutex_unlock(&iface->mutex);
if (rc == 0 && size == I2C_SMBUS_WORD_DATA && rw == I2C_SMBUS_READ)
data->word = le16_to_cpu(cur_word);
#ifdef DEBUG
dev_dbg(&adapter->dev, "transfer done, result: %d", rc);
if (buffer) {
int i;
printk(" data:");
for (i = 0; i < len; ++i)
printk(" %02x", buffer[i]);
}
printk("\n");
#endif
return rc;
}
static u32 scx200_acb_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_I2C_BLOCK;
}
/* For now, we only handle combined mode (smbus) */
static const struct i2c_algorithm scx200_acb_algorithm = {
.smbus_xfer = scx200_acb_smbus_xfer,
.functionality = scx200_acb_func,
};
static struct scx200_acb_iface *scx200_acb_list;
static DEFINE_MUTEX(scx200_acb_list_mutex);
static int scx200_acb_probe(struct scx200_acb_iface *iface)
{
u8 val;
/* Disable the ACCESS.bus device and Configure the SCL
frequency: 16 clock cycles */
outb(0x70, ACBCTL2);
if (inb(ACBCTL2) != 0x70) {
pr_debug("ACBCTL2 readback failed\n");
return -ENXIO;
}
outb(inb(ACBCTL1) | ACBCTL1_NMINTE, ACBCTL1);
val = inb(ACBCTL1);
if (val) {
pr_debug("disabled, but ACBCTL1=0x%02x\n", val);
return -ENXIO;
}
outb(inb(ACBCTL2) | ACBCTL2_ENABLE, ACBCTL2);
outb(inb(ACBCTL1) | ACBCTL1_NMINTE, ACBCTL1);
val = inb(ACBCTL1);
if ((val & ACBCTL1_NMINTE) != ACBCTL1_NMINTE) {
pr_debug("enabled, but NMINTE won't be set, ACBCTL1=0x%02x\n",
val);
return -ENXIO;
}
return 0;
}
static struct scx200_acb_iface *scx200_create_iface(const char *text,
struct device *dev, int index)
{
struct scx200_acb_iface *iface;
struct i2c_adapter *adapter;
iface = kzalloc(sizeof(*iface), GFP_KERNEL);
if (!iface)
return NULL;
adapter = &iface->adapter;
i2c_set_adapdata(adapter, iface);
snprintf(adapter->name, sizeof(adapter->name), "%s ACB%d", text, index);
adapter->owner = THIS_MODULE;
adapter->algo = &scx200_acb_algorithm;
adapter->class = I2C_CLASS_HWMON | I2C_CLASS_SPD;
adapter->dev.parent = dev;
mutex_init(&iface->mutex);
return iface;
}
static int scx200_acb_create(struct scx200_acb_iface *iface)
{
struct i2c_adapter *adapter;
int rc;
adapter = &iface->adapter;
rc = scx200_acb_probe(iface);
if (rc) {
pr_warn("probe failed\n");
return rc;
}
scx200_acb_reset(iface);
if (i2c_add_adapter(adapter) < 0) {
pr_err("failed to register\n");
return -ENODEV;
}
if (!adapter->dev.parent) {
/* If there's no dev, we're tracking (ISA) ifaces manually */
mutex_lock(&scx200_acb_list_mutex);
iface->next = scx200_acb_list;
scx200_acb_list = iface;
mutex_unlock(&scx200_acb_list_mutex);
}
return 0;
}
static struct scx200_acb_iface *scx200_create_dev(const char *text,
unsigned long base, int index, struct device *dev)
{
struct scx200_acb_iface *iface;
int rc;
iface = scx200_create_iface(text, dev, index);
if (iface == NULL)
return NULL;
if (!request_region(base, 8, iface->adapter.name)) {
pr_err("can't allocate io 0x%lx-0x%lx\n", base, base + 8 - 1);
goto errout_free;
}
iface->base = base;
rc = scx200_acb_create(iface);
if (rc == 0)
return iface;
release_region(base, 8);
errout_free:
kfree(iface);
return NULL;
}
static int scx200_probe(struct platform_device *pdev)
{
struct scx200_acb_iface *iface;
struct resource *res;
res = platform_get_resource(pdev, IORESOURCE_IO, 0);
if (!res) {
dev_err(&pdev->dev, "can't fetch device resource info\n");
return -ENODEV;
}
iface = scx200_create_dev("CS5535", res->start, 0, &pdev->dev);
if (!iface)
return -EIO;
dev_info(&pdev->dev, "SCx200 device '%s' registered\n",
iface->adapter.name);
platform_set_drvdata(pdev, iface);
return 0;
}
static void scx200_cleanup_iface(struct scx200_acb_iface *iface)
{
i2c_del_adapter(&iface->adapter);
release_region(iface->base, 8);
kfree(iface);
}
static int scx200_remove(struct platform_device *pdev)
{
struct scx200_acb_iface *iface;
iface = platform_get_drvdata(pdev);
scx200_cleanup_iface(iface);
return 0;
}
static struct platform_driver scx200_pci_driver = {
.driver = {
.name = "cs5535-smb",
},
.probe = scx200_probe,
.remove = scx200_remove,
};
static const struct pci_device_id scx200_isa[] = {
{ PCI_DEVICE(PCI_VENDOR_ID_NS, PCI_DEVICE_ID_NS_SCx200_BRIDGE) },
{ PCI_DEVICE(PCI_VENDOR_ID_NS, PCI_DEVICE_ID_NS_SC1100_BRIDGE) },
{ 0, }
};
static __init void scx200_scan_isa(void)
{
int i;
if (!pci_dev_present(scx200_isa))
return;
for (i = 0; i < MAX_DEVICES; ++i) {
if (base[i] == 0)
continue;
/* XXX: should we care about failures? */
scx200_create_dev("SCx200", base[i], i, NULL);
}
}
static int __init scx200_acb_init(void)
{
pr_debug("NatSemi SCx200 ACCESS.bus Driver\n");
/* First scan for ISA-based devices */
scx200_scan_isa(); /* XXX: should we care about errors? */
/* If at least one bus was created, init must succeed */
if (scx200_acb_list)
return 0;
/* No ISA devices; register the platform driver for PCI-based devices */
return platform_driver_register(&scx200_pci_driver);
}
static void __exit scx200_acb_cleanup(void)
{
struct scx200_acb_iface *iface;
platform_driver_unregister(&scx200_pci_driver);
mutex_lock(&scx200_acb_list_mutex);
while ((iface = scx200_acb_list) != NULL) {
scx200_acb_list = iface->next;
mutex_unlock(&scx200_acb_list_mutex);
scx200_cleanup_iface(iface);
mutex_lock(&scx200_acb_list_mutex);
}
mutex_unlock(&scx200_acb_list_mutex);
}
module_init(scx200_acb_init);
module_exit(scx200_acb_cleanup);