Subject: [PATCH v2 3/3] watchdog: zx2967: add watchdog controller driver for ZTE's zx2967 family

From: [email-masked] (Shawn Guo)
Date: Fri, 20 Jan 2017 14:08:18 +0800

On Thu, Jan 19, 2017 at 09:59:52AM +0800, Baoyou Xie wrote:
> This patch adds watchdog controller driver for ZTE's zx2967 family.
> 
> Signed-off-by: Baoyou Xie <[email-masked]>
> ---
>  drivers/watchdog/Kconfig      |  10 ++
>  drivers/watchdog/Makefile     |   1 +
>  drivers/watchdog/zx2967_wdt.c | 383 ++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 394 insertions(+)
>  create mode 100644 drivers/watchdog/zx2967_wdt.c
> 
> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
> index acb00b5..05093a2 100644
> --- a/drivers/watchdog/Kconfig
> +++ b/drivers/watchdog/Kconfig
> @@ -714,6 +714,16 @@ config ASPEED_WATCHDOG
>  	  To compile this driver as a module, choose M here: the
>  	  module will be called aspeed_wdt.
>  
> +config ZX2967_WATCHDOG
> +	tristate "ZTE zx2967 SoCs watchdog support"
> +	depends on ARCH_ZX
> +	select WATCHDOG_CORE
> +	help
> +	  Say Y here to include support for the watchdog timer
> +	  in ZTE zx2967 SoCs.
> +	  To compile this driver as a module, choose M here: the
> +	  module will be called zx2967_wdt.
> +
>  # AVR32 Architecture
>  
>  config AT32AP700X_WDT
> diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
> index 0c3d35e..bf2d296 100644
> --- a/drivers/watchdog/Makefile
> +++ b/drivers/watchdog/Makefile
> @@ -82,6 +82,7 @@ obj-$(CONFIG_BCM7038_WDT) += bcm7038_wdt.o
>  obj-$(CONFIG_ATLAS7_WATCHDOG) += atlas7_wdt.o
>  obj-$(CONFIG_RENESAS_WDT) += renesas_wdt.o
>  obj-$(CONFIG_ASPEED_WATCHDOG) += aspeed_wdt.o
> +obj-$(CONFIG_ZX2967_WATCHDOG) += zx2967_wdt.o
>  
>  # AVR32 Architecture
>  obj-$(CONFIG_AT32AP700X_WDT) += at32ap700x_wdt.o
> diff --git a/drivers/watchdog/zx2967_wdt.c b/drivers/watchdog/zx2967_wdt.c
> new file mode 100644
> index 0000000..35eaecd
> --- /dev/null
> +++ b/drivers/watchdog/zx2967_wdt.c
> @@ -0,0 +1,383 @@
> +/*
> + * watchdog driver for ZTE's zx2967 family
> + *
> + * Copyright (C) 2017 ZTE Ltd.
> + *
> + * Author: Baoyou Xie <[email-masked]>
> + *
> + * License terms: GNU General Public License (GPL) version 2
> + */
> +
> +#include <linux/clk.h>
> +#include <linux/delay.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/reboot.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			0x3f
> +
> +#define ZX2967_WDT_CFG_DIV(n)			((((n) & 0xff) - 1) << 8)
> +#define ZX2967_WDT_START_EN			0x1
> +
> +#define ZX2967_WDT_WRITEKEY			0x12340000
> +
> +#define ZX2967_WDT_DIV_DEFAULT			16
> +#define ZX2967_WDT_DEFAULT_TIMEOUT		32
> +#define ZX2967_WDT_MIN_TIMEOUT			1
> +#define ZX2967_WDT_MAX_TIMEOUT			500
> +#define ZX2967_WDT_MAX_COUNT			0xffff
> +
> +#define ZX2967_WDT_FLAG_REBOOT_MON		(1 << 0)
> +
> +#define ZX2967_RESET_MASK_REG			0xb0
> +
> +struct zx2967_wdt {
> +	struct device		*dev;
> +	struct clk		*clock;
> +	void __iomem		*reg_base;
> +	unsigned int		conf;
> +	unsigned int		load;
> +	unsigned int		flags;
> +	struct watchdog_device	wdt_device;
> +	struct notifier_block	restart_handler;
> +	struct notifier_block	reboot_handler;
> +};
> +
> +#define zx2967_wdt_read_reg(r)                  readl_relaxed(r)
> +
> +static inline void
> +zx2967_wdt_write_reg(u32 val, void __iomem *addr)
> +{
> +	writel_relaxed(val | ZX2967_WDT_WRITEKEY, addr);
> +}

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);
}

This is what I would suggest to make the caller a bit easier.  Anyway,
it's just a suggestion, not a strong opinion.

> +
> +static void zx2967_wdt_refresh(struct zx2967_wdt *wdt)
> +{
> +	u32 val;
> +
> +	val = zx2967_wdt_read_reg(wdt->reg_base + ZX2967_WDT_REFRESH_REG);
> +	val ^= ZX2967_WDT_REFRESH_MASK;
> +	zx2967_wdt_write_reg(val, wdt->reg_base + ZX2967_WDT_REFRESH_REG);
> +}
> +
> +static unsigned int
> +__zx2967_wdt_set_timeout(struct zx2967_wdt *wdt, unsigned int timeout)
> +{
> +	unsigned int freq = clk_get_rate(wdt->clock);
> +	unsigned int divisor = ZX2967_WDT_DIV_DEFAULT;
> +	unsigned int count;
> +
> +	count = timeout * 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_write_reg(ZX2967_WDT_CFG_DIV(divisor),
> +			     wdt->reg_base + ZX2967_WDT_CFG_REG);
> +	zx2967_wdt_write_reg(count, wdt->reg_base + ZX2967_WDT_LOAD_REG);
> +	zx2967_wdt_refresh(wdt);
> +	wdt->load = count;
> +
> +	return (count * divisor) / freq;
> +}
> +
> +static int zx2967_wdt_set_timeout(struct watchdog_device *wdd,
> +				  unsigned int timeout)
> +{
> +	struct zx2967_wdt *wdt = watchdog_get_drvdata(wdd);
> +
> +	if (watchdog_timeout_invalid(&wdt->wdt_device, timeout)) {
> +		dev_err(wdt->dev, "timeout %d is invalid\n", timeout);
> +		return -EINVAL;
> +	}
> +
> +	wdd->timeout = __zx2967_wdt_set_timeout(wdt, timeout);
> +
> +	return 0;
> +}
> +
> +static void __zx2967_wdt_start(struct zx2967_wdt *wdt)
> +{
> +	u32 val;
> +
> +	val = zx2967_wdt_read_reg(wdt->reg_base + ZX2967_WDT_START_REG);
> +	val |= ZX2967_WDT_START_EN;
> +	zx2967_wdt_write_reg(val, wdt->reg_base + ZX2967_WDT_START_REG);
> +}
> +
> +static void __zx2967_wdt_stop(struct zx2967_wdt *wdt)
> +{
> +	u32 val;
> +
> +	val = zx2967_wdt_read_reg(wdt->reg_base + ZX2967_WDT_START_REG);
> +	val &= ~ZX2967_WDT_START_EN;
> +	zx2967_wdt_write_reg(val, wdt->reg_base + ZX2967_WDT_START_REG);
> +}
> +
> +static int zx2967_wdt_start(struct watchdog_device *wdd)
> +{
> +	struct zx2967_wdt *wdt = watchdog_get_drvdata(wdd);
> +
> +	__zx2967_wdt_stop(wdt);
> +	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,
> +	.firmware_version =	0,
> +	.identity         =	"zx2967 watchdog",
> +};
> +
> +static 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_fix_sysdown(struct zx2967_wdt *wdt)
> +{
> +	__zx2967_wdt_stop(wdt);
> +	__zx2967_wdt_set_timeout(wdt, 15);
> +	__zx2967_wdt_start(wdt);
> +}
> +
> +static int zx2967_wdt_notify_sys(struct notifier_block *this,
> +			     unsigned long code, void *unused)
> +{
> +	struct zx2967_wdt *wdt = container_of(this, struct zx2967_wdt,
> +					      reboot_handler);
> +
> +	wdt->flags |= ZX2967_WDT_FLAG_REBOOT_MON;
> +	switch (code) {
> +	case SYS_HALT:
> +	case SYS_POWER_OFF:
> +	case SYS_RESTART:
> +		zx2967_wdt_fix_sysdown(wdt);
> +		break;
> +	default:
> +		break;
> +	}
> +
> +	return 0;
> +}
> +
> +static int zx2967_wdt_restart(struct notifier_block *this,
> +			      unsigned long mode, void *cmd)
> +{
> +	struct zx2967_wdt *wdt;
> +
> +	wdt = container_of(this, struct zx2967_wdt, restart_handler);
> +
> +	zx2967_wdt_stop(&wdt->wdt_device);
> +
> +	zx2967_wdt_write_reg(0x80, wdt->reg_base + ZX2967_WDT_LOAD_REG);
> +	zx2967_wdt_refresh(wdt);
> +	zx2967_wdt_write_reg(ZX2967_WDT_START_EN,
> +			     wdt->reg_base + ZX2967_WDT_START_REG);
> +
> +	zx2967_wdt_start(&wdt->wdt_device);
> +	/* wait for reset*/
> +	mdelay(500);
> +
> +	return NOTIFY_DONE;
> +}
> +
> +static void zx2967_wdt_reset_sysctrl(struct device *dev)
> +{
> +	int ret;
> +	struct device_node *np = NULL;
> +	void __iomem *regmap;
> +	unsigned int  val, mask, config;
> +	struct of_phandle_args out_args;
> +
> +	ret = of_parse_phandle_with_fixed_args(dev->of_node,
> +			"wdt-reset-sysctrl", 2, 0, &out_args);
> +	if (ret) {
> +		dev_info(dev, "have no wdt-reset-sysctrl node");

wdt-reset-sysctrl is not a node but a property.  Also, the call can fail
on other reasons, e.g. the arguments are not two.  So I suggest the
message like "failed to parse wdt-reset-sysctrl".

> +		return;
> +	}
> +	config = out_args.args[0];
> +	mask = out_args.args[1];
> +
> +	regmap = syscon_node_to_regmap(out_args.np);
> +	if (IS_ERR(regmap))
> +		goto out;
> +
> +	ret = regmap_read(regmap, ZX2967_RESET_MASK_REG, &val);

I think this register offset can also be an argument of phandle in
device tree.

> +
> +	val &= ~mask;
> +	val |= config;
> +	regmap_write(regmap, ZX2967_RESET_MASK_REG, val);

regmap_update_bits() can be used.

> +out:
> +	of_node_put(np);
> +}
> +
> +static int zx2967_wdt_probe(struct platform_device *pdev)
> +{
> +	struct device *dev;
> +	struct zx2967_wdt *wdt;
> +	struct resource *base;
> +	int err, ret = 0;
> +	unsigned int rate;
> +
> +	struct reset_control *rstc;
> +
> +	dev = &pdev->dev;
> +
> +	wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
> +	if (!wdt)
> +		return -ENOMEM;
> +
> +	platform_set_drvdata(pdev, wdt);
> +
> +	wdt->dev = dev;
> +	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 = &pdev->dev;
> +
> +	base = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	wdt->reg_base = devm_ioremap_resource(dev, base);
> +	if (IS_ERR(wdt->reg_base)) {
> +		dev_err(dev, "ioremap failed\n");
> +		return PTR_ERR(wdt->reg_base);
> +	}
> +
> +	zx2967_wdt_reset_sysctrl(dev);
> +
> +	wdt->reboot_handler.notifier_call = zx2967_wdt_notify_sys;
> +	ret = register_reboot_notifier(&wdt->reboot_handler);
> +	wdt->clock = devm_clk_get(dev, "wdtclk");

devm_clk_get(dev, NULL), so that clock-names can be saved from DT.

> +	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;
> +	}
> +
> +	rate = clk_get_rate(wdt->clock);
> +	if (rate == 24000000)
> +		clk_set_rate(wdt->clock, 32768);

What's the logic behind this?  We need to set the frequency to 32768
only when it's 24000000?  Any other frequency will just work?

> +
> +	rstc = devm_reset_control_get(dev, "wdtrst");

devm_reset_control_get(dev, NULL), so that reset-names can be saved.

> +	if (!rstc) {
> +		dev_err(dev, "rstc get failed");

Will it still work if "reset" property is missing?  If yes, the property
should be documented as optional, not required.  If no, we should stop
probing and return error right here.

> +	} else {
> +		reset_control_assert(rstc);
> +		mdelay(10);
> +		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);
> +
> +	zx2967_wdt_stop(&wdt->wdt_device);
> +
> +	err = watchdog_register_device(&wdt->wdt_device);

Why not use 'ret' directly?

Shawn

> +	if (unlikely(err)) {
> +		ret = err;
> +		goto fail_register;
> +	}
> +
> +	wdt->restart_handler.notifier_call = zx2967_wdt_restart;
> +	wdt->restart_handler.priority = 128;
> +	ret = register_restart_handler(&wdt->restart_handler);
> +	if (ret) {
> +		dev_err(dev, "cannot register restart handler, %d\n", ret);
> +		goto fail_restart;
> +	}
> +
> +	dev_info(dev, "watchdog enabled (timeout=%d sec, nowayout=%d)",
> +		 wdt->wdt_device.timeout, WATCHDOG_NOWAYOUT);
> +
> +	return 0;
> +
> +fail_restart:
> +	watchdog_unregister_device(&wdt->wdt_device);
> +fail_register:
> +	clk_disable_unprepare(wdt->clock);
> +	return ret;
> +}
> +
> +static int zx2967_wdt_remove(struct platform_device *pdev)
> +{
> +	struct zx2967_wdt *wdt = platform_get_drvdata(pdev);
> +
> +	unregister_restart_handler(&wdt->restart_handler);
> +	watchdog_unregister_device(&wdt->wdt_device);
> +	clk_disable_unprepare(wdt->clock);
> +
> +	return 0;
> +}
> +
> +static void zx2967_wdt_shutdown(struct platform_device *pdev)
> +{
> +	struct zx2967_wdt *wdt = platform_get_drvdata(pdev);
> +
> +	if (!(wdt->flags & ZX2967_WDT_FLAG_REBOOT_MON))
> +		zx2967_wdt_stop(&wdt->wdt_device);
> +}
> +
> +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,
> +	.remove		= zx2967_wdt_remove,
> +	.shutdown	= zx2967_wdt_shutdown,
> +	.driver		= {
> +		.name	= "zx2967-wdt",
> +		.of_match_table	= of_match_ptr(zx2967_wdt_match),
> +	},
> +};
> +module_platform_driver(zx2967_wdt_driver);
> +
> +MODULE_AUTHOR("Baoyou Xie <[email-masked]>");
> +MODULE_DESCRIPTION("ZTE zx2967 Watchdog Device Driver");
> +MODULE_LICENSE("GPL v2");
> -- 
> 2.7.4
>