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/*
* watchdog driver for ZTE's zx2967 family
*
* Copyright (C) 2017 ZTE Ltd.
*
* Author: Baoyou Xie <baoyou.xie@linaro.org>
*
* License terms: GNU General Public License (GPL) version 2
*/
#include <linux/clk.h>
#include <linux/io.h>
#include <linux/mfd/syscon.h>
#include <linux/module.h>
#include <linux/of_address.h>
#include <linux/platform_device.h>
#include <linux/regmap.h>
#include <linux/reset.h>
#include <linux/watchdog.h>
#define ZX2967_WDT_CFG_REG 0x4
#define ZX2967_WDT_LOAD_REG 0x8
#define ZX2967_WDT_REFRESH_REG 0x18
#define ZX2967_WDT_START_REG 0x1c
#define ZX2967_WDT_REFRESH_MASK GENMASK(5, 0)
#define ZX2967_WDT_CFG_DIV(n) ((((n) & 0xff) - 1) << 8)
#define ZX2967_WDT_START_EN 0x1
/*
* Hardware magic number.
* When watchdog reg is written, the lowest 16 bits are valid, but
* the highest 16 bits should be always this number.
*/
#define ZX2967_WDT_WRITEKEY (0x1234 << 16)
#define ZX2967_WDT_VAL_MASK GENMASK(15, 0)
#define ZX2967_WDT_DIV_DEFAULT 16
#define ZX2967_WDT_DEFAULT_TIMEOUT 32
#define ZX2967_WDT_MIN_TIMEOUT 1
#define ZX2967_WDT_MAX_TIMEOUT 524
#define ZX2967_WDT_MAX_COUNT 0xffff
#define ZX2967_WDT_CLK_FREQ 0x8000
#define ZX2967_WDT_FLAG_REBOOT_MON BIT(0)
struct zx2967_wdt {
struct watchdog_device wdt_device;
void __iomem *reg_base;
struct clk *clock;
};
static inline u32 zx2967_wdt_readl(struct zx2967_wdt *wdt, u16 reg)
{
return readl_relaxed(wdt->reg_base + reg);
}
static inline void zx2967_wdt_writel(struct zx2967_wdt *wdt, u16 reg, u32 val)
{
writel_relaxed(val | ZX2967_WDT_WRITEKEY, wdt->reg_base + reg);
}
static void zx2967_wdt_refresh(struct zx2967_wdt *wdt)
{
u32 val;
val = zx2967_wdt_readl(wdt, ZX2967_WDT_REFRESH_REG);
/*
* Bit 4-5, 1 and 2: refresh config info
* Bit 2-3, 1 and 2: refresh counter
* Bit 0-1, 1 and 2: refresh int-value
* we shift each group value between 1 and 2 to refresh all data.
*/
val ^= ZX2967_WDT_REFRESH_MASK;
zx2967_wdt_writel(wdt, ZX2967_WDT_REFRESH_REG,
val & ZX2967_WDT_VAL_MASK);
}
static int
zx2967_wdt_set_timeout(struct watchdog_device *wdd, unsigned int timeout)
{
struct zx2967_wdt *wdt = watchdog_get_drvdata(wdd);
unsigned int divisor = ZX2967_WDT_DIV_DEFAULT;
u32 count;
count = timeout * ZX2967_WDT_CLK_FREQ;
if (count > divisor * ZX2967_WDT_MAX_COUNT)
divisor = DIV_ROUND_UP(count, ZX2967_WDT_MAX_COUNT);
count = DIV_ROUND_UP(count, divisor);
zx2967_wdt_writel(wdt, ZX2967_WDT_CFG_REG,
ZX2967_WDT_CFG_DIV(divisor) & ZX2967_WDT_VAL_MASK);
zx2967_wdt_writel(wdt, ZX2967_WDT_LOAD_REG,
count & ZX2967_WDT_VAL_MASK);
zx2967_wdt_refresh(wdt);
wdd->timeout = (count * divisor) / ZX2967_WDT_CLK_FREQ;
return 0;
}
static void __zx2967_wdt_start(struct zx2967_wdt *wdt)
{
u32 val;
val = zx2967_wdt_readl(wdt, ZX2967_WDT_START_REG);
val |= ZX2967_WDT_START_EN;
zx2967_wdt_writel(wdt, ZX2967_WDT_START_REG,
val & ZX2967_WDT_VAL_MASK);
}
static void __zx2967_wdt_stop(struct zx2967_wdt *wdt)
{
u32 val;
val = zx2967_wdt_readl(wdt, ZX2967_WDT_START_REG);
val &= ~ZX2967_WDT_START_EN;
zx2967_wdt_writel(wdt, ZX2967_WDT_START_REG,
val & ZX2967_WDT_VAL_MASK);
}
static int zx2967_wdt_start(struct watchdog_device *wdd)
{
struct zx2967_wdt *wdt = watchdog_get_drvdata(wdd);
zx2967_wdt_set_timeout(wdd, wdd->timeout);
__zx2967_wdt_start(wdt);
return 0;
}
static int zx2967_wdt_stop(struct watchdog_device *wdd)
{
struct zx2967_wdt *wdt = watchdog_get_drvdata(wdd);
__zx2967_wdt_stop(wdt);
return 0;
}
static int zx2967_wdt_keepalive(struct watchdog_device *wdd)
{
struct zx2967_wdt *wdt = watchdog_get_drvdata(wdd);
zx2967_wdt_refresh(wdt);
return 0;
}
#define ZX2967_WDT_OPTIONS \
(WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE)
static const struct watchdog_info zx2967_wdt_ident = {
.options = ZX2967_WDT_OPTIONS,
.identity = "zx2967 watchdog",
};
static const struct watchdog_ops zx2967_wdt_ops = {
.owner = THIS_MODULE,
.start = zx2967_wdt_start,
.stop = zx2967_wdt_stop,
.ping = zx2967_wdt_keepalive,
.set_timeout = zx2967_wdt_set_timeout,
};
static void zx2967_wdt_reset_sysctrl(struct device *dev)
{
int ret;
void __iomem *regmap;
unsigned int offset, mask, config;
struct of_phandle_args out_args;
ret = of_parse_phandle_with_fixed_args(dev->of_node,
"zte,wdt-reset-sysctrl", 3, 0, &out_args);
if (ret)
return;
offset = out_args.args[0];
config = out_args.args[1];
mask = out_args.args[2];
regmap = syscon_node_to_regmap(out_args.np);
if (IS_ERR(regmap)) {
of_node_put(out_args.np);
return;
}
regmap_update_bits(regmap, offset, mask, config);
of_node_put(out_args.np);
}
static void zx2967_clk_disable_unprepare(void *data)
{
clk_disable_unprepare(data);
}
static int zx2967_wdt_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
struct zx2967_wdt *wdt;
int ret;
struct reset_control *rstc;
wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
if (!wdt)
return -ENOMEM;
platform_set_drvdata(pdev, wdt);
wdt->wdt_device.info = &zx2967_wdt_ident;
wdt->wdt_device.ops = &zx2967_wdt_ops;
wdt->wdt_device.timeout = ZX2967_WDT_DEFAULT_TIMEOUT;
wdt->wdt_device.max_timeout = ZX2967_WDT_MAX_TIMEOUT;
wdt->wdt_device.min_timeout = ZX2967_WDT_MIN_TIMEOUT;
wdt->wdt_device.parent = dev;
wdt->reg_base = devm_platform_ioremap_resource(pdev, 0);
if (IS_ERR(wdt->reg_base))
return PTR_ERR(wdt->reg_base);
zx2967_wdt_reset_sysctrl(dev);
wdt->clock = devm_clk_get(dev, NULL);
if (IS_ERR(wdt->clock)) {
dev_err(dev, "failed to find watchdog clock source\n");
return PTR_ERR(wdt->clock);
}
ret = clk_prepare_enable(wdt->clock);
if (ret < 0) {
dev_err(dev, "failed to enable clock\n");
return ret;
}
ret = devm_add_action_or_reset(dev, zx2967_clk_disable_unprepare,
wdt->clock);
if (ret)
return ret;
clk_set_rate(wdt->clock, ZX2967_WDT_CLK_FREQ);
rstc = devm_reset_control_get_exclusive(dev, NULL);
if (IS_ERR(rstc)) {
dev_err(dev, "failed to get rstc");
return PTR_ERR(rstc);
}
reset_control_assert(rstc);
reset_control_deassert(rstc);
watchdog_set_drvdata(&wdt->wdt_device, wdt);
watchdog_init_timeout(&wdt->wdt_device,
ZX2967_WDT_DEFAULT_TIMEOUT, dev);
watchdog_set_nowayout(&wdt->wdt_device, WATCHDOG_NOWAYOUT);
ret = devm_watchdog_register_device(dev, &wdt->wdt_device);
if (ret)
return ret;
dev_info(dev, "watchdog enabled (timeout=%d sec, nowayout=%d)",
wdt->wdt_device.timeout, WATCHDOG_NOWAYOUT);
return 0;
}
static const struct of_device_id zx2967_wdt_match[] = {
{ .compatible = "zte,zx296718-wdt", },
{}
};
MODULE_DEVICE_TABLE(of, zx2967_wdt_match);
static struct platform_driver zx2967_wdt_driver = {
.probe = zx2967_wdt_probe,
.driver = {
.name = "zx2967-wdt",
.of_match_table = of_match_ptr(zx2967_wdt_match),
},
};
module_platform_driver(zx2967_wdt_driver);
MODULE_AUTHOR("Baoyou Xie <baoyou.xie@linaro.org>");
MODULE_DESCRIPTION("ZTE zx2967 Watchdog Device Driver");
MODULE_LICENSE("GPL v2");
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