linux/drivers/watchdog/exar_wdt.c

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// SPDX-License-Identifier: GPL-2.0+
/*
* exar_wdt.c - Driver for the watchdog present in some
* Exar/MaxLinear UART chips like the XR28V38x.
*
* (c) Copyright 2022 D. Müller <d.mueller@elsoft.ch>.
*
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/io.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/watchdog.h>
#define DRV_NAME "exar_wdt"
static const unsigned short sio_config_ports[] = { 0x2e, 0x4e };
static const unsigned char sio_enter_keys[] = { 0x67, 0x77, 0x87, 0xA0 };
#define EXAR_EXIT_KEY 0xAA
#define EXAR_LDN 0x07
#define EXAR_DID 0x20
#define EXAR_VID 0x23
#define EXAR_WDT 0x26
#define EXAR_ACT 0x30
#define EXAR_RTBASE 0x60
#define EXAR_WDT_LDEV 0x08
#define EXAR_VEN_ID 0x13A8
#define EXAR_DEV_382 0x0382
#define EXAR_DEV_384 0x0384
/* WDT runtime registers */
#define WDT_CTRL 0x00
#define WDT_VAL 0x01
#define WDT_UNITS_10MS 0x0 /* the 10 millisec unit of the HW is not used */
#define WDT_UNITS_SEC 0x2
#define WDT_UNITS_MIN 0x4
/* default WDT control for WDTOUT signal activ / rearm by read */
#define EXAR_WDT_DEF_CONF 0
struct wdt_pdev_node {
struct list_head list;
struct platform_device *pdev;
const char name[16];
};
struct wdt_priv {
/* the lock for WDT io operations */
spinlock_t io_lock;
struct resource wdt_res;
struct watchdog_device wdt_dev;
unsigned short did;
unsigned short config_port;
unsigned char enter_key;
unsigned char unit;
unsigned char timeout;
};
#define WATCHDOG_TIMEOUT 60
static int timeout = WATCHDOG_TIMEOUT;
module_param(timeout, int, 0);
MODULE_PARM_DESC(timeout,
"Watchdog timeout in seconds. 1<=timeout<=15300, default="
__MODULE_STRING(WATCHDOG_TIMEOUT) ".");
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 exar_sio_enter(const unsigned short config_port,
const unsigned char key)
{
if (!request_muxed_region(config_port, 2, DRV_NAME))
return -EBUSY;
/* write the ENTER-KEY twice */
outb(key, config_port);
outb(key, config_port);
return 0;
}
static void exar_sio_exit(const unsigned short config_port)
{
outb(EXAR_EXIT_KEY, config_port);
release_region(config_port, 2);
}
static unsigned char exar_sio_read(const unsigned short config_port,
const unsigned char reg)
{
outb(reg, config_port);
return inb(config_port + 1);
}
static void exar_sio_write(const unsigned short config_port,
const unsigned char reg, const unsigned char val)
{
outb(reg, config_port);
outb(val, config_port + 1);
}
static unsigned short exar_sio_read16(const unsigned short config_port,
const unsigned char reg)
{
unsigned char msb, lsb;
msb = exar_sio_read(config_port, reg);
lsb = exar_sio_read(config_port, reg + 1);
return (msb << 8) | lsb;
}
static void exar_sio_select_wdt(const unsigned short config_port)
{
exar_sio_write(config_port, EXAR_LDN, EXAR_WDT_LDEV);
}
static void exar_wdt_arm(const struct wdt_priv *priv)
{
unsigned short rt_base = priv->wdt_res.start;
/* write timeout value twice to arm watchdog */
outb(priv->timeout, rt_base + WDT_VAL);
outb(priv->timeout, rt_base + WDT_VAL);
}
static void exar_wdt_disarm(const struct wdt_priv *priv)
{
unsigned short rt_base = priv->wdt_res.start;
/*
* use two accesses with different values to make sure
* that a combination of a previous single access and
* the ones below with the same value are not falsely
* interpreted as "arm watchdog"
*/
outb(0xFF, rt_base + WDT_VAL);
outb(0, rt_base + WDT_VAL);
}
static int exar_wdt_start(struct watchdog_device *wdog)
{
struct wdt_priv *priv = watchdog_get_drvdata(wdog);
unsigned short rt_base = priv->wdt_res.start;
spin_lock(&priv->io_lock);
exar_wdt_disarm(priv);
outb(priv->unit, rt_base + WDT_CTRL);
exar_wdt_arm(priv);
spin_unlock(&priv->io_lock);
return 0;
}
static int exar_wdt_stop(struct watchdog_device *wdog)
{
struct wdt_priv *priv = watchdog_get_drvdata(wdog);
spin_lock(&priv->io_lock);
exar_wdt_disarm(priv);
spin_unlock(&priv->io_lock);
return 0;
}
static int exar_wdt_keepalive(struct watchdog_device *wdog)
{
struct wdt_priv *priv = watchdog_get_drvdata(wdog);
unsigned short rt_base = priv->wdt_res.start;
spin_lock(&priv->io_lock);
/* reading the WDT_VAL reg will feed the watchdog */
inb(rt_base + WDT_VAL);
spin_unlock(&priv->io_lock);
return 0;
}
static int exar_wdt_set_timeout(struct watchdog_device *wdog, unsigned int t)
{
struct wdt_priv *priv = watchdog_get_drvdata(wdog);
bool unit_min = false;
/*
* if new timeout is bigger then 255 seconds, change the
* unit to minutes and round the timeout up to the next whole minute
*/
if (t > 255) {
unit_min = true;
t = DIV_ROUND_UP(t, 60);
}
/* save for later use in exar_wdt_start() */
priv->unit = unit_min ? WDT_UNITS_MIN : WDT_UNITS_SEC;
priv->timeout = t;
wdog->timeout = unit_min ? t * 60 : t;
if (watchdog_hw_running(wdog))
exar_wdt_start(wdog);
return 0;
}
static const struct watchdog_info exar_wdt_info = {
.options = WDIOF_KEEPALIVEPING |
WDIOF_SETTIMEOUT |
WDIOF_MAGICCLOSE,
.identity = "Exar/MaxLinear XR28V38x Watchdog",
};
static const struct watchdog_ops exar_wdt_ops = {
.owner = THIS_MODULE,
.start = exar_wdt_start,
.stop = exar_wdt_stop,
.ping = exar_wdt_keepalive,
.set_timeout = exar_wdt_set_timeout,
};
static int exar_wdt_config(struct watchdog_device *wdog,
const unsigned char conf)
{
struct wdt_priv *priv = watchdog_get_drvdata(wdog);
int ret;
ret = exar_sio_enter(priv->config_port, priv->enter_key);
if (ret)
return ret;
exar_sio_select_wdt(priv->config_port);
exar_sio_write(priv->config_port, EXAR_WDT, conf);
exar_sio_exit(priv->config_port);
return 0;
}
static int __init exar_wdt_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
struct wdt_priv *priv = dev->platform_data;
struct watchdog_device *wdt_dev = &priv->wdt_dev;
struct resource *res;
int ret;
res = platform_get_resource(pdev, IORESOURCE_IO, 0);
if (!res)
return -ENXIO;
spin_lock_init(&priv->io_lock);
wdt_dev->info = &exar_wdt_info;
wdt_dev->ops = &exar_wdt_ops;
wdt_dev->min_timeout = 1;
wdt_dev->max_timeout = 255 * 60;
watchdog_init_timeout(wdt_dev, timeout, NULL);
watchdog_set_nowayout(wdt_dev, nowayout);
watchdog_stop_on_reboot(wdt_dev);
watchdog_stop_on_unregister(wdt_dev);
watchdog_set_drvdata(wdt_dev, priv);
ret = exar_wdt_config(wdt_dev, EXAR_WDT_DEF_CONF);
if (ret)
return ret;
exar_wdt_set_timeout(wdt_dev, timeout);
/* Make sure that the watchdog is not running */
exar_wdt_stop(wdt_dev);
ret = devm_watchdog_register_device(dev, wdt_dev);
if (ret)
return ret;
dev_info(dev, "XR28V%X WDT initialized. timeout=%d sec (nowayout=%d)\n",
priv->did, timeout, nowayout);
return 0;
}
static unsigned short __init exar_detect(const unsigned short config_port,
const unsigned char key,
unsigned short *rt_base)
{
int ret;
unsigned short base = 0;
unsigned short vid, did;
ret = exar_sio_enter(config_port, key);
if (ret)
return 0;
vid = exar_sio_read16(config_port, EXAR_VID);
did = exar_sio_read16(config_port, EXAR_DID);
/* check for the vendor and device IDs we currently know about */
if (vid == EXAR_VEN_ID &&
(did == EXAR_DEV_382 ||
did == EXAR_DEV_384)) {
exar_sio_select_wdt(config_port);
/* is device active? */
if (exar_sio_read(config_port, EXAR_ACT) == 0x01)
base = exar_sio_read16(config_port, EXAR_RTBASE);
}
exar_sio_exit(config_port);
if (base) {
pr_debug("Found a XR28V%X WDT (conf: 0x%x / rt: 0x%04x)\n",
did, config_port, base);
*rt_base = base;
return did;
}
return 0;
}
static struct platform_driver exar_wdt_driver = {
.driver = {
.name = DRV_NAME,
},
};
static LIST_HEAD(pdev_list);
static int __init exar_wdt_register(struct wdt_priv *priv, const int idx)
{
struct wdt_pdev_node *n;
n = kzalloc(sizeof(*n), GFP_KERNEL);
if (!n)
return -ENOMEM;
INIT_LIST_HEAD(&n->list);
scnprintf((char *)n->name, sizeof(n->name), DRV_NAME ".%d", idx);
priv->wdt_res.name = n->name;
n->pdev = platform_device_register_resndata(NULL, DRV_NAME, idx,
&priv->wdt_res, 1,
priv, sizeof(*priv));
if (IS_ERR(n->pdev)) {
int err = PTR_ERR(n->pdev);
kfree(n);
return err;
}
list_add_tail(&n->list, &pdev_list);
return 0;
}
static void exar_wdt_unregister(void)
{
struct wdt_pdev_node *n, *t;
list_for_each_entry_safe(n, t, &pdev_list, list) {
platform_device_unregister(n->pdev);
list_del(&n->list);
kfree(n);
}
}
static int __init exar_wdt_init(void)
{
int ret, i, j, idx = 0;
/* search for active Exar watchdogs on all possible locations */
for (i = 0; i < ARRAY_SIZE(sio_config_ports); i++) {
for (j = 0; j < ARRAY_SIZE(sio_enter_keys); j++) {
unsigned short did, rt_base = 0;
did = exar_detect(sio_config_ports[i],
sio_enter_keys[j],
&rt_base);
if (did) {
struct wdt_priv priv = {
.wdt_res = DEFINE_RES_IO(rt_base, 2),
.did = did,
.config_port = sio_config_ports[i],
.enter_key = sio_enter_keys[j],
};
ret = exar_wdt_register(&priv, idx);
if (!ret)
idx++;
}
}
}
if (!idx)
return -ENODEV;
ret = platform_driver_probe(&exar_wdt_driver, exar_wdt_probe);
if (ret)
exar_wdt_unregister();
return ret;
}
static void __exit exar_wdt_exit(void)
{
exar_wdt_unregister();
platform_driver_unregister(&exar_wdt_driver);
}
module_init(exar_wdt_init);
module_exit(exar_wdt_exit);
MODULE_AUTHOR("David Müller <d.mueller@elsoft.ch>");
MODULE_DESCRIPTION("Exar/MaxLinear Watchdog Driver");
MODULE_LICENSE("GPL");