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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* GE watchdog userspace interface
*
* Author: Martyn Welch <martyn.welch@ge.com>
*
* Copyright 2008 GE Intelligent Platforms Embedded Systems, Inc.
*
* Based on: mv64x60_wdt.c (MV64X60 watchdog userspace interface)
* Author: James Chapman <jchapman@katalix.com>
*/
/* TODO:
* This driver does not provide support for the hardwares capability of sending
* an interrupt at a programmable threshold.
*
* This driver currently can only support 1 watchdog - there are 2 in the
* hardware that this driver supports. Thus one could be configured as a
* process-based watchdog (via /dev/watchdog), the second (using the interrupt
* capabilities) a kernel-based watchdog.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/kernel.h>
#include <linux/compiler.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/miscdevice.h>
#include <linux/watchdog.h>
#include <linux/fs.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/of_platform.h>
#include <linux/io.h>
#include <linux/uaccess.h>
#include <sysdev/fsl_soc.h>
/*
* The watchdog configuration register contains a pair of 2-bit fields,
* 1. a reload field, bits 27-26, which triggers a reload of
* the countdown register, and
* 2. an enable field, bits 25-24, which toggles between
* enabling and disabling the watchdog timer.
* Bit 31 is a read-only field which indicates whether the
* watchdog timer is currently enabled.
*
* The low 24 bits contain the timer reload value.
*/
#define GEF_WDC_ENABLE_SHIFT 24
#define GEF_WDC_SERVICE_SHIFT 26
#define GEF_WDC_ENABLED_SHIFT 31
#define GEF_WDC_ENABLED_TRUE 1
#define GEF_WDC_ENABLED_FALSE 0
/* Flags bits */
#define GEF_WDOG_FLAG_OPENED 0
static unsigned long wdt_flags;
static int wdt_status;
static void __iomem *gef_wdt_regs;
static int gef_wdt_timeout;
static int gef_wdt_count;
static unsigned int bus_clk;
static char expect_close;
static DEFINE_SPINLOCK(gef_wdt_spinlock);
static bool nowayout = WATCHDOG_NOWAYOUT;
module_param(nowayout, bool, 0);
MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
static int gef_wdt_toggle_wdc(int enabled_predicate, int field_shift)
{
u32 data;
u32 enabled;
int ret = 0;
spin_lock(&gef_wdt_spinlock);
data = ioread32be(gef_wdt_regs);
enabled = (data >> GEF_WDC_ENABLED_SHIFT) & 1;
/* only toggle the requested field if enabled state matches predicate */
if ((enabled ^ enabled_predicate) == 0) {
/* We write a 1, then a 2 -- to the appropriate field */
data = (1 << field_shift) | gef_wdt_count;
iowrite32be(data, gef_wdt_regs);
data = (2 << field_shift) | gef_wdt_count;
iowrite32be(data, gef_wdt_regs);
ret = 1;
}
spin_unlock(&gef_wdt_spinlock);
return ret;
}
static void gef_wdt_service(void)
{
gef_wdt_toggle_wdc(GEF_WDC_ENABLED_TRUE,
GEF_WDC_SERVICE_SHIFT);
}
static void gef_wdt_handler_enable(void)
{
if (gef_wdt_toggle_wdc(GEF_WDC_ENABLED_FALSE,
GEF_WDC_ENABLE_SHIFT)) {
gef_wdt_service();
pr_notice("watchdog activated\n");
}
}
static void gef_wdt_handler_disable(void)
{
if (gef_wdt_toggle_wdc(GEF_WDC_ENABLED_TRUE,
GEF_WDC_ENABLE_SHIFT))
pr_notice("watchdog deactivated\n");
}
static void gef_wdt_set_timeout(unsigned int timeout)
{
/* maximum bus cycle count is 0xFFFFFFFF */
if (timeout > 0xFFFFFFFF / bus_clk)
timeout = 0xFFFFFFFF / bus_clk;
/* Register only holds upper 24 bits, bit shifted into lower 24 */
gef_wdt_count = (timeout * bus_clk) >> 8;
gef_wdt_timeout = timeout;
}
static ssize_t gef_wdt_write(struct file *file, const char __user *data,
size_t len, loff_t *ppos)
{
if (len) {
if (!nowayout) {
size_t i;
expect_close = 0;
for (i = 0; i != len; i++) {
char c;
if (get_user(c, data + i))
return -EFAULT;
if (c == 'V')
expect_close = 42;
}
}
gef_wdt_service();
}
return len;
}
static long gef_wdt_ioctl(struct file *file, unsigned int cmd,
unsigned long arg)
{
int timeout;
int options;
void __user *argp = (void __user *)arg;
static const struct watchdog_info info = {
.options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE |
WDIOF_KEEPALIVEPING,
.firmware_version = 0,
.identity = "GE watchdog",
};
switch (cmd) {
case WDIOC_GETSUPPORT:
if (copy_to_user(argp, &info, sizeof(info)))
return -EFAULT;
break;
case WDIOC_GETSTATUS:
case WDIOC_GETBOOTSTATUS:
if (put_user(wdt_status, (int __user *)argp))
return -EFAULT;
wdt_status &= ~WDIOF_KEEPALIVEPING;
break;
case WDIOC_SETOPTIONS:
if (get_user(options, (int __user *)argp))
return -EFAULT;
if (options & WDIOS_DISABLECARD)
gef_wdt_handler_disable();
if (options & WDIOS_ENABLECARD)
gef_wdt_handler_enable();
break;
case WDIOC_KEEPALIVE:
gef_wdt_service();
wdt_status |= WDIOF_KEEPALIVEPING;
break;
case WDIOC_SETTIMEOUT:
if (get_user(timeout, (int __user *)argp))
return -EFAULT;
gef_wdt_set_timeout(timeout);
/* Fall through */
case WDIOC_GETTIMEOUT:
if (put_user(gef_wdt_timeout, (int __user *)argp))
return -EFAULT;
break;
default:
return -ENOTTY;
}
return 0;
}
static int gef_wdt_open(struct inode *inode, struct file *file)
{
if (test_and_set_bit(GEF_WDOG_FLAG_OPENED, &wdt_flags))
return -EBUSY;
if (nowayout)
__module_get(THIS_MODULE);
gef_wdt_handler_enable();
return stream_open(inode, file);
}
static int gef_wdt_release(struct inode *inode, struct file *file)
{
if (expect_close == 42)
gef_wdt_handler_disable();
else {
pr_crit("unexpected close, not stopping timer!\n");
gef_wdt_service();
}
expect_close = 0;
clear_bit(GEF_WDOG_FLAG_OPENED, &wdt_flags);
return 0;
}
static const struct file_operations gef_wdt_fops = {
.owner = THIS_MODULE,
.llseek = no_llseek,
.write = gef_wdt_write,
.unlocked_ioctl = gef_wdt_ioctl,
.open = gef_wdt_open,
.release = gef_wdt_release,
};
static struct miscdevice gef_wdt_miscdev = {
.minor = WATCHDOG_MINOR,
.name = "watchdog",
.fops = &gef_wdt_fops,
};
static int gef_wdt_probe(struct platform_device *dev)
{
int timeout = 10;
u32 freq;
bus_clk = 133; /* in MHz */
freq = fsl_get_sys_freq();
if (freq != -1)
bus_clk = freq;
/* Map devices registers into memory */
gef_wdt_regs = of_iomap(dev->dev.of_node, 0);
if (gef_wdt_regs == NULL)
return -ENOMEM;
gef_wdt_set_timeout(timeout);
gef_wdt_handler_disable(); /* in case timer was already running */
return misc_register(&gef_wdt_miscdev);
}
static int gef_wdt_remove(struct platform_device *dev)
{
misc_deregister(&gef_wdt_miscdev);
gef_wdt_handler_disable();
iounmap(gef_wdt_regs);
return 0;
}
static const struct of_device_id gef_wdt_ids[] = {
{
.compatible = "gef,fpga-wdt",
},
{},
};
MODULE_DEVICE_TABLE(of, gef_wdt_ids);
static struct platform_driver gef_wdt_driver = {
.driver = {
.name = "gef_wdt",
.of_match_table = gef_wdt_ids,
},
.probe = gef_wdt_probe,
.remove = gef_wdt_remove,
};
static int __init gef_wdt_init(void)
{
pr_info("GE watchdog driver\n");
return platform_driver_register(&gef_wdt_driver);
}
static void __exit gef_wdt_exit(void)
{
platform_driver_unregister(&gef_wdt_driver);
}
module_init(gef_wdt_init);
module_exit(gef_wdt_exit);
MODULE_AUTHOR("Martyn Welch <martyn.welch@ge.com>");
MODULE_DESCRIPTION("GE watchdog driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:gef_wdt");
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