// SPDX-License-Identifier: GPL-2.0-only
/* cpwd.c - driver implementation for hardware watchdog
* timers found on Sun Microsystems CP1400 and CP1500 boards.
*
* This device supports both the generic Linux watchdog
* interface and Solaris-compatible ioctls as best it is
* able.
*
* NOTE: CP1400 systems appear to have a defective intr_mask
* register on the PLD, preventing the disabling of
* timer interrupts. We use a timer to periodically
* reset 'stopped' watchdogs on affected platforms.
*
* Copyright (c) 2000 Eric Brower (ebrower@usa.net)
* Copyright (C) 2008 David S. Miller <davem@davemloft.net>
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/errno.h>
#include <linux/major.h>
#include <linux/miscdevice.h>
#include <linux/interrupt.h>
#include <linux/ioport.h>
#include <linux/timer.h>
#include <linux/compat.h>
#include <linux/slab.h>
#include <linux/mutex.h>
#include <linux/io.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/uaccess.h>
#include <asm/irq.h>
#include <asm/watchdog.h>
#define DRIVER_NAME "cpwd"
#define WD_OBPNAME "watchdog"
#define WD_BADMODEL "SUNW,501-5336"
#define WD_BTIMEOUT (jiffies + (HZ * 1000))
#define WD_BLIMIT 0xFFFF
#define WD0_MINOR 212
#define WD1_MINOR 213
#define WD2_MINOR 214
/* Internal driver definitions. */
#define WD0_ID 0
#define WD1_ID 1
#define WD2_ID 2
#define WD_NUMDEVS 3
#define WD_INTR_OFF 0
#define WD_INTR_ON 1
#define WD_STAT_INIT 0x01 /* Watchdog timer is initialized */
#define WD_STAT_BSTOP 0x02 /* Watchdog timer is brokenstopped */
#define WD_STAT_SVCD 0x04 /* Watchdog interrupt occurred */
/* Register value definitions
*/
#define WD0_INTR_MASK 0x01 /* Watchdog device interrupt masks */
#define WD1_INTR_MASK 0x02
#define WD2_INTR_MASK 0x04
#define WD_S_RUNNING 0x01 /* Watchdog device status running */
#define WD_S_EXPIRED 0x02 /* Watchdog device status expired */
struct cpwd {
void __iomem *regs;
spinlock_t lock;
unsigned int irq;
unsigned long timeout;
bool enabled;
bool reboot;
bool broken;
bool initialized;
struct {
struct miscdevice misc;
void __iomem *regs;
u8 intr_mask;
u8 runstatus;
u16 timeout;
} devs[WD_NUMDEVS];
};
static DEFINE_MUTEX(cpwd_mutex);
static struct cpwd *cpwd_device;
/* Sun uses Altera PLD EPF8820ATC144-4
* providing three hardware watchdogs:
*
* 1) RIC - sends an interrupt when triggered
* 2) XIR - asserts XIR_B_RESET when triggered, resets CPU
* 3) POR - asserts POR_B_RESET when triggered, resets CPU, backplane, board
*
*** Timer register block definition (struct wd_timer_regblk)
*
* dcntr and limit registers (halfword access):
* -------------------
* | 15 | ...| 1 | 0 |
* -------------------
* |- counter val -|
* -------------------
* dcntr - Current 16-bit downcounter value.
* When downcounter reaches '0' watchdog expires.
* Reading this register resets downcounter with
* 'limit' value.
* limit - 16-bit countdown value in 1/10th second increments.
* Writing this register begins countdown with input value.
* Reading from this register does not affect counter.
* NOTES: After watchdog reset, dcntr and limit contain '1'
*
* status register (byte access):
* ---------------------------
* | 7 | ... | 2 | 1 | 0 |
* --------------+------------
* |- UNUSED -| EXP | RUN |
* ---------------------------
* status- Bit 0 - Watchdog is running
* Bit 1 - Watchdog has expired
*
*** PLD register block definition (struct wd_pld_regblk)
*
* intr_mask register (byte access):
* ---------------------------------
* | 7 | ... | 3 | 2 | 1 | 0 |
* +-------------+------------------
* |- UNUSED -| WD3 | WD2 | WD1 |
* ---------------------------------
* WD3 - 1 == Interrupt disabled for watchdog 3
* WD2 - 1 == Interrupt disabled for watchdog 2
* WD1 - 1 == Interrupt disabled for watchdog 1
*
* pld_status register (byte access):
* UNKNOWN, MAGICAL MYSTERY REGISTER
*
*/
#define WD_TIMER_REGSZ 16
#define WD0_OFF 0
#define WD1_OFF (WD_TIMER_REGSZ * 1)
#define WD2_OFF (WD_TIMER_REGSZ * 2)
#define PLD_OFF (WD_TIMER_REGSZ * 3)
#define WD_DCNTR 0x00
#define WD_LIMIT 0x04
#define WD_STATUS 0x08
#define PLD_IMASK (PLD_OFF + 0x00)
#define PLD_STATUS (PLD_OFF + 0x04)
static struct timer_list cpwd_timer;
static int wd0_timeout;
static int wd1_timeout;
static int wd2_timeout;
module_param(wd0_timeout, int, 0);
MODULE_PARM_DESC(wd0_timeout, "Default watchdog0 timeout in 1/10secs");
module_param(wd1_timeout, int, 0);
MODULE_PARM_DESC(wd1_timeout, "Default watchdog1 timeout in 1/10secs");
module_param(wd2_timeout, int, 0);
MODULE_PARM_DESC(wd2_timeout, "Default watchdog2 timeout in 1/10secs");
MODULE_AUTHOR("Eric Brower <ebrower@usa.net>");
MODULE_DESCRIPTION("Hardware watchdog driver for Sun Microsystems CP1400/1500");
MODULE_LICENSE("GPL");
static void cpwd_writew(u16 val, void __iomem *addr)
{
writew(cpu_to_le16(val), addr);
}
static u16 cpwd_readw(void __iomem *addr)
{
u16 val = readw(addr);
return le16_to_cpu(val);
}
static void cpwd_writeb(u8 val, void __iomem *addr)
{
writeb(val, addr);
}
static u8 cpwd_readb(void __iomem *addr)
{
return readb(addr);
}
/* Enable or disable watchdog interrupts
* Because of the CP1400 defect this should only be
* called during initialzation or by wd_[start|stop]timer()
*
* index - sub-device index, or -1 for 'all'
* enable - non-zero to enable interrupts, zero to disable
*/
static void cpwd_toggleintr(struct cpwd *p, int index, int enable)
{
unsigned char curregs = cpwd_readb(p->regs + PLD_IMASK);
unsigned char setregs =
(index == -1) ?
(WD0_INTR_MASK | WD1_INTR_MASK | WD2_INTR_MASK) :
(p->devs[index].intr_mask);
if (enable == WD_INTR_ON)
curregs &= ~setregs;
else
curregs |= setregs;
cpwd_writeb(curregs, p->regs + PLD_IMASK);
}
/* Restarts timer with maximum limit value and
* does not unset 'brokenstop' value.
*/
static void cpwd_resetbrokentimer(struct cpwd *p, int index)
{
cpwd_toggleintr(p, index, WD_INTR_ON);
cpwd_writew(WD_BLIMIT, p->devs[index].regs + WD_LIMIT);
}
/* Timer method called to reset stopped watchdogs--
* because of the PLD bug on CP1400, we cannot mask
* interrupts within the PLD so me must continually
* reset the timers ad infinitum.
*/
static void cpwd_brokentimer(struct timer_list *unused)
{
struct cpwd *p = cpwd_device;
int id, tripped = 0;
/* kill a running timer instance, in case we
* were called directly instead of by kernel timer
*/
if (timer_pending(&cpwd_timer))
del_timer(&cpwd_timer);
for (id = 0; id < WD_NUMDEVS; id++) {
if (p->devs[id].runstatus & WD_STAT_BSTOP) {
++tripped;
cpwd_resetbrokentimer(p, id);
}
}
if (tripped) {
/* there is at least one timer brokenstopped-- reschedule */
cpwd_timer.expires = WD_BTIMEOUT;
add_timer(&cpwd_timer);
}
}
/* Reset countdown timer with 'limit' value and continue countdown.
* This will not start a stopped timer.
*/
static void cpwd_pingtimer(struct cpwd *p, int index)
{
if (cpwd_readb(p->devs[index].regs + WD_STATUS) & WD_S_RUNNING)
cpwd_readw(p->devs[index].regs + WD_DCNTR);
}
/* Stop a running watchdog timer-- the timer actually keeps
* running, but the interrupt is masked so that no action is
* taken upon expiration.
*/
static void cpwd_stoptimer(struct cpwd *p, int index)
{
if (cpwd_readb(p->devs[index].regs + WD_STATUS) & WD_S_RUNNING) {
cpwd_toggleintr(p, index, WD_INTR_OFF);
if (p->broken) {
p->devs[index].runstatus |= WD_STAT_BSTOP;
cpwd_brokentimer(NULL);
}
}
}
/* Start a watchdog timer with the specified limit value
* If the watchdog is running, it will be restarted with
* the provided limit value.
*
* This function will enable interrupts on the specified
* watchdog.
*/
static void cpwd_starttimer(struct cpwd *p, int index)
{
if (p->broken)
p->devs[index].runstatus &= ~WD_STAT_BSTOP;
p->devs[index].runstatus &= ~WD_STAT_SVCD;
cpwd_writew(p->devs[index].timeout, p->devs[index].regs + WD_LIMIT);
cpwd_toggleintr(p, index, WD_INTR_ON);
}
static int cpwd_getstatus(struct cpwd *p, int index)
{
unsigned char stat = cpwd_readb(p->devs[index].regs + WD_STATUS);
unsigned char intr = cpwd_readb(p->devs[index].regs + PLD_IMASK);
unsigned char ret = WD_STOPPED;
/* determine STOPPED */
if (!stat)
return ret;
/* determine EXPIRED vs FREERUN vs RUNNING */
else if (WD_S_EXPIRED & stat) {
ret = WD_EXPIRED;
} else if (WD_S_RUNNING & stat) {
if (intr & p->devs[index].intr_mask) {
ret = WD_FREERUN;
} else {
/* Fudge WD_EXPIRED status for defective CP1400--
* IF timer is running
* AND brokenstop is set
* AND an interrupt has been serviced
* we are WD_EXPIRED.
*
* IF timer is running
* AND brokenstop is set
* AND no interrupt has been serviced
* we are WD_FREERUN.
*/
if (p->broken &&
(p->devs[index].runstatus & WD_STAT_BSTOP)) {
if (p->devs[index].runstatus & WD_STAT_SVCD) {
ret = WD_EXPIRED;
} else {
/* we could as well pretend
* we are expired */
ret = WD_FREERUN;
}
} else {
ret = WD_RUNNING;
}
}
}
/* determine SERVICED */
if (p->devs[index].runstatus & WD_STAT_SVCD)
ret |= WD_SERVICED;
return ret;
}
static irqreturn_t cpwd_interrupt(int irq, void *dev_id)
{
struct cpwd *p = dev_id;
/* Only WD0 will interrupt-- others are NMI and we won't
* see them here....
*/
spin_lock_irq(&p->lock);
cpwd_stoptimer(p, WD0_ID);
p->devs[WD0_ID].runstatus |= WD_STAT_SVCD;
spin_unlock_irq(&p->lock);
return IRQ_HANDLED;
}
static int cpwd_open(struct inode *inode, struct file *f)
{
struct cpwd *p = cpwd_device;
mutex_lock(&cpwd_mutex);
switch (iminor(inode)) {
case WD0_MINOR:
case WD1_MINOR:
case WD2_MINOR:
break;
default:
mutex_unlock(&cpwd_mutex);
return -ENODEV;
}
/* Register IRQ on first open of device */
if (!p->initialized) {
if (request_irq(p->irq, &cpwd_interrupt,
IRQF_SHARED, DRIVER_NAME, p)) {
pr_err("Cannot register IRQ %d\n", p->irq);
mutex_unlock(&cpwd_mutex);
return -EBUSY;
}
p->initialized = true;
}
mutex_unlock(&cpwd_mutex);
return stream_open(inode, f);
}
static int cpwd_release(struct inode *inode, struct file *file)
{
return 0;
}
static long cpwd_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
static const struct watchdog_info info = {
.options = WDIOF_SETTIMEOUT,
.firmware_version = 1,
.identity = DRIVER_NAME,
};
void __user *argp = (void __user *)arg;
struct inode *inode = file_inode(file);
int index = iminor(inode) - WD0_MINOR;
struct cpwd *p = cpwd_device;
int setopt = 0;
switch (cmd) {
/* Generic Linux IOCTLs */
case WDIOC_GETSUPPORT:
if (copy_to_user(argp, &info, sizeof(struct watchdog_info)))
return -EFAULT;
break;
case WDIOC_GETSTATUS:
case WDIOC_GETBOOTSTATUS:
if (put_user(0, (int __user *)argp))
return -EFAULT;
break;
case WDIOC_KEEPALIVE:
cpwd_pingtimer(p, index);
break;
case WDIOC_SETOPTIONS:
if (copy_from_user(&setopt, argp, sizeof(unsigned int)))
return -EFAULT;
if (setopt & WDIOS_DISABLECARD) {
if (p->enabled)
return -EINVAL;
cpwd_stoptimer(p, index);
} else if (setopt & WDIOS_ENABLECARD) {
cpwd_starttimer(p, index);
} else {
return -EINVAL;
}
break;
/* Solaris-compatible IOCTLs */
case WIOCGSTAT:
setopt = cpwd_getstatus(p, index);
if (copy_to_user(argp, &setopt, sizeof(unsigned int)))
return -EFAULT;
break;
case WIOCSTART:
cpwd_starttimer(p, index);
break;
case WIOCSTOP:
if (p->enabled)
return -EINVAL;
cpwd_stoptimer(p, index);
break;
default:
return -EINVAL;
}
return 0;
}
static long cpwd_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
return cpwd_ioctl(file, cmd, (unsigned long)compat_ptr(arg));
}
static ssize_t cpwd_write(struct file *file, const char __user *buf,
size_t count, loff_t *ppos)
{
struct inode *inode = file_inode(file);
struct cpwd *p = cpwd_device;
int index = iminor(inode);
if (count) {
cpwd_pingtimer(p, index);
return 1;
}
return 0;
}
static ssize_t cpwd_read(struct file *file, char __user *buffer,
size_t count, loff_t *ppos)
{
return -EINVAL;
}
static const struct file_operations cpwd_fops = {
.owner = THIS_MODULE,
.unlocked_ioctl = cpwd_ioctl,
.compat_ioctl = cpwd_compat_ioctl,
.open = cpwd_open,
.write = cpwd_write,
.read = cpwd_read,
.release = cpwd_release,
.llseek = no_llseek,
};
static int cpwd_probe(struct platform_device *op)
{
struct device_node *options;
const char *str_prop;
const void *prop_val;
int i, err = -EINVAL;
struct cpwd *p;
if (cpwd_device)
return -EINVAL;
p = devm_kzalloc(&op->dev, sizeof(*p), GFP_KERNEL);
if (!p)
return -ENOMEM;
p->irq = op->archdata.irqs[0];
spin_lock_init(&p->lock);
p->regs = of_ioremap(&op->resource[0], 0,
4 * WD_TIMER_REGSZ, DRIVER_NAME);
if (!p->regs) {
pr_err("Unable to map registers\n");
return -ENOMEM;
}
options = of_find_node_by_path("/options");
if (!options) {
err = -ENODEV;
pr_err("Unable to find /options node\n");
goto out_iounmap;
}
prop_val = of_get_property(options, "watchdog-enable?", NULL);
p->enabled = (prop_val ? true : false);
prop_val = of_get_property(options, "watchdog-reboot?", NULL);
p->reboot = (prop_val ? true : false);
str_prop = of_get_property(options, "watchdog-timeout", NULL);
if (str_prop)
p->timeout = simple_strtoul(str_prop, NULL, 10);
of_node_put(options);
/* CP1400s seem to have broken PLD implementations-- the
* interrupt_mask register cannot be written, so no timer
* interrupts can be masked within the PLD.
*/
str_prop = of_get_property(op->dev.of_node, "model", NULL);
p->broken = (str_prop && !strcmp(str_prop, WD_BADMODEL));
if (!p->enabled)
cpwd_toggleintr(p, -1, WD_INTR_OFF);
for (i = 0; i < WD_NUMDEVS; i++) {
static const char *cpwd_names[] = { "RIC", "XIR", "POR" };
static int *parms[] = { &wd0_timeout,
&wd1_timeout,
&wd2_timeout };
struct miscdevice *mp = &p->devs[i].misc;
mp->minor = WD0_MINOR + i;
mp->name = cpwd_names[i];
mp->fops = &cpwd_fops;
p->devs[i].regs = p->regs + (i * WD_TIMER_REGSZ);
p->devs[i].intr_mask = (WD0_INTR_MASK << i);
p->devs[i].runstatus &= ~WD_STAT_BSTOP;
p->devs[i].runstatus |= WD_STAT_INIT;
p->devs[i].timeout = p->timeout;
if (*parms[i])
p->devs[i].timeout = *parms[i];
err = misc_register(&p->devs[i].misc);
if (err) {
pr_err("Could not register misc device for dev %d\n",
i);
goto out_unregister;
}
}
if (p->broken) {
timer_setup(&cpwd_timer, cpwd_brokentimer, 0);
cpwd_timer.expires = WD_BTIMEOUT;
pr_info("PLD defect workaround enabled for model %s\n",
WD_BADMODEL);
}
platform_set_drvdata(op, p);
cpwd_device = p;
return 0;
out_unregister:
for (i--; i >= 0; i--)
misc_deregister(&p->devs[i].misc);
out_iounmap:
of_iounmap(&op->resource[0], p->regs, 4 * WD_TIMER_REGSZ);
return err;
}
static void cpwd_remove(struct platform_device *op)
{
struct cpwd *p = platform_get_drvdata(op);
int i;
for (i = 0; i < WD_NUMDEVS; i++) {
misc_deregister(&p->devs[i].misc);
if (!p->enabled) {
cpwd_stoptimer(p, i);
if (p->devs[i].runstatus & WD_STAT_BSTOP)
cpwd_resetbrokentimer(p, i);
}
}
if (p->broken)
del_timer_sync(&cpwd_timer);
if (p->initialized)
free_irq(p->irq, p);
of_iounmap(&op->resource[0], p->regs, 4 * WD_TIMER_REGSZ);
cpwd_device = NULL;
}
static const struct of_device_id cpwd_match[] = {
{
.name = "watchdog",
},
{},
};
MODULE_DEVICE_TABLE(of, cpwd_match);
static struct platform_driver cpwd_driver = {
.driver = {
.name = DRIVER_NAME,
.of_match_table = cpwd_match,
},
.probe = cpwd_probe,
.remove_new = cpwd_remove,
};
module_platform_driver(cpwd_driver);