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/*
* Watchdog driver for TS-4800 based boards
*
* Copyright (c) 2015 - Savoir-faire Linux
*
* This file is licensed under the terms of the GNU General Public
* License version 2. This program is licensed "as is" without any
* warranty of any kind, whether express or implied.
*/
#include <linux/kernel.h>
#include <linux/mfd/syscon.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/regmap.h>
#include <linux/watchdog.h>
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) ")");
/* possible feed values */
#define TS4800_WDT_FEED_2S 0x1
#define TS4800_WDT_FEED_10S 0x2
#define TS4800_WDT_DISABLE 0x3
struct ts4800_wdt {
struct watchdog_device wdd;
struct regmap *regmap;
u32 feed_offset;
u32 feed_val;
};
/*
* TS-4800 supports the following timeout values:
*
* value desc
* ---------------------
* 0 feed for 338ms
* 1 feed for 2.706s
* 2 feed for 10.824s
* 3 disable watchdog
*
* Keep the regmap/timeout map ordered by timeout
*/
static const struct {
const int timeout;
const int regval;
} ts4800_wdt_map[] = {
{ 2, TS4800_WDT_FEED_2S },
{ 10, TS4800_WDT_FEED_10S },
};
#define MAX_TIMEOUT_INDEX (ARRAY_SIZE(ts4800_wdt_map) - 1)
static void ts4800_write_feed(struct ts4800_wdt *wdt, u32 val)
{
regmap_write(wdt->regmap, wdt->feed_offset, val);
}
static int ts4800_wdt_start(struct watchdog_device *wdd)
{
struct ts4800_wdt *wdt = watchdog_get_drvdata(wdd);
ts4800_write_feed(wdt, wdt->feed_val);
return 0;
}
static int ts4800_wdt_stop(struct watchdog_device *wdd)
{
struct ts4800_wdt *wdt = watchdog_get_drvdata(wdd);
ts4800_write_feed(wdt, TS4800_WDT_DISABLE);
return 0;
}
static int ts4800_wdt_set_timeout(struct watchdog_device *wdd,
unsigned int timeout)
{
struct ts4800_wdt *wdt = watchdog_get_drvdata(wdd);
int i;
for (i = 0; i < MAX_TIMEOUT_INDEX; i++) {
if (ts4800_wdt_map[i].timeout >= timeout)
break;
}
wdd->timeout = ts4800_wdt_map[i].timeout;
wdt->feed_val = ts4800_wdt_map[i].regval;
return 0;
}
static const struct watchdog_ops ts4800_wdt_ops = {
.owner = THIS_MODULE,
.start = ts4800_wdt_start,
.stop = ts4800_wdt_stop,
.set_timeout = ts4800_wdt_set_timeout,
};
static const struct watchdog_info ts4800_wdt_info = {
.options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING,
.identity = "TS-4800 Watchdog",
};
static int ts4800_wdt_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
struct device_node *np = dev->of_node;
struct device_node *syscon_np;
struct watchdog_device *wdd;
struct ts4800_wdt *wdt;
u32 reg;
int ret;
syscon_np = of_parse_phandle(np, "syscon", 0);
if (!syscon_np) {
dev_err(dev, "no syscon property\n");
return -ENODEV;
}
ret = of_property_read_u32_index(np, "syscon", 1, ®);
if (ret < 0) {
dev_err(dev, "no offset in syscon\n");
return ret;
}
/* allocate memory for watchdog struct */
wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
if (!wdt)
return -ENOMEM;
/* set regmap and offset to know where to write */
wdt->feed_offset = reg;
wdt->regmap = syscon_node_to_regmap(syscon_np);
of_node_put(syscon_np);
if (IS_ERR(wdt->regmap)) {
dev_err(dev, "cannot get parent's regmap\n");
return PTR_ERR(wdt->regmap);
}
/* Initialize struct watchdog_device */
wdd = &wdt->wdd;
wdd->parent = dev;
wdd->info = &ts4800_wdt_info;
wdd->ops = &ts4800_wdt_ops;
wdd->min_timeout = ts4800_wdt_map[0].timeout;
wdd->max_timeout = ts4800_wdt_map[MAX_TIMEOUT_INDEX].timeout;
watchdog_set_drvdata(wdd, wdt);
watchdog_set_nowayout(wdd, nowayout);
watchdog_init_timeout(wdd, 0, dev);
/*
* As this watchdog supports only a few values, ts4800_wdt_set_timeout
* must be called to initialize timeout and feed_val with valid values.
* Default to maximum timeout if none, or an invalid one, is provided in
* device tree.
*/
if (!wdd->timeout)
wdd->timeout = wdd->max_timeout;
ts4800_wdt_set_timeout(wdd, wdd->timeout);
/*
* The feed register is write-only, so it is not possible to determine
* watchdog's state. Disable it to be in a known state.
*/
ts4800_wdt_stop(wdd);
ret = devm_watchdog_register_device(dev, wdd);
if (ret)
return ret;
platform_set_drvdata(pdev, wdt);
dev_info(dev, "initialized (timeout = %d sec, nowayout = %d)\n",
wdd->timeout, nowayout);
return 0;
}
static const struct of_device_id ts4800_wdt_of_match[] = {
{ .compatible = "technologic,ts4800-wdt", },
{ },
};
MODULE_DEVICE_TABLE(of, ts4800_wdt_of_match);
static struct platform_driver ts4800_wdt_driver = {
.probe = ts4800_wdt_probe,
.driver = {
.name = "ts4800_wdt",
.of_match_table = ts4800_wdt_of_match,
},
};
module_platform_driver(ts4800_wdt_driver);
MODULE_AUTHOR("Damien Riegel <damien.riegel@savoirfairelinux.com>");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS("platform:ts4800_wdt");
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