Re: [PATCH v3 1/2] watchdog: add Alphascale asm9260-wdt driver

Guenter Roeck
2015-11-25T03:22:15Z

On 11/24/2015 01:40 PM, Oleksij Rempel wrote:
> Add WD support for Alphascale asm9260 SoC. This driver
> provide support for different function modes:
> - HW mode to trigger SoC reset on timeout
> - SW mode do soft reset if needed
> - DEBUG mode
>
> Optional support for stopping watchdog. If reset binding are not provided
> this driver will work in nowayout mode.

I think this is no longer optional ?

>
> Signed-off-by: Oleksij Rempel <linux@rempel-privat.de>
> ---
> drivers/watchdog/Kconfig | 10 ++
> drivers/watchdog/Makefile | 1 +
> drivers/watchdog/asm9260_wdt.c | 400 +++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 411 insertions(+)
> create mode 100644 drivers/watchdog/asm9260_wdt.c
>
> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
> index c68edc1..9cd9b75 100644
> --- a/drivers/watchdog/Kconfig
> +++ b/drivers/watchdog/Kconfig
> @@ -173,6 +173,16 @@ config ARM_SP805_WATCHDOG
> ARM Primecell SP805 Watchdog timer. This will reboot your system when
> the timeout is reached.
>
> +config ASM9260_WATCHDOG
> + tristate "Alphascale ASM9260 watchdog"
> + depends on MACH_ASM9260
> + depends on OF
> + select WATCHDOG_CORE
> + select RESET_CONTROLLER
> + help
> + Watchdog timer embedded into Alphascale asm9260 chips. This will reboot your
> + system when the timeout is reached.
> +
> config AT91RM9200_WATCHDOG
> tristate "AT91RM9200 watchdog"
> depends on SOC_AT91RM9200 && MFD_SYSCON
> diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
> index 0c616e3..bd7b0cd 100644
> --- a/drivers/watchdog/Makefile
> +++ b/drivers/watchdog/Makefile
> @@ -30,6 +30,7 @@ obj-$(CONFIG_USBPCWATCHDOG) += pcwd_usb.o
>
> # ARM Architecture
> obj-$(CONFIG_ARM_SP805_WATCHDOG) += sp805_wdt.o
> +obj-$(CONFIG_ASM9260_WATCHDOG) += asm9260_wdt.o
> obj-$(CONFIG_AT91RM9200_WATCHDOG) += at91rm9200_wdt.o
> obj-$(CONFIG_AT91SAM9X_WATCHDOG) += at91sam9_wdt.o
> obj-$(CONFIG_CADENCE_WATCHDOG) += cadence_wdt.o
> diff --git a/drivers/watchdog/asm9260_wdt.c b/drivers/watchdog/asm9260_wdt.c
> new file mode 100644
> index 0000000..c8daeff
> --- /dev/null
> +++ b/drivers/watchdog/asm9260_wdt.c
> @@ -0,0 +1,400 @@
> +/*
> + * Watchdog driver for Alphascale ASM9260.
> + *
> + * Copyright (c) 2014 Oleksij Rempel <linux@rempel-privat.de>
> + *
> + * Licensed under GPLv2 or later.
> + */
> +
> +#include <linux/bitops.h>
> +#include <linux/clk.h>
> +#include <linux/delay.h>
> +#include <linux/interrupt.h>
> +#include <linux/io.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/platform_device.h>
> +#include <linux/reboot.h>
> +#include <linux/reset.h>
> +#include <linux/watchdog.h>
> +
> +#define CLOCK_FREQ 1000000
> +
> +/* Watchdog Mode register */
> +#define HW_WDMOD 0x00
> +/* Wake interrupt. Set by HW, can't be cleared. */
> +#define BM_MOD_WDINT BIT(3)
> +/* This bit set if timeout reached. Cleared by SW. */
> +#define BM_MOD_WDTOF BIT(2)
> +/* HW Reset on timeout */
> +#define BM_MOD_WDRESET BIT(1)
> +/* WD enable */
> +#define BM_MOD_WDEN BIT(0)
> +
> +/*
> + * Watchdog Timer Constant register
> + * Minimal value is 0xff, the meaning of this value
> + * depends on used clock: T = WDCLK * (0xff + 1) * 4
> + */
> +#define HW_WDTC 0x04
> +#define BM_WDTC_MAX(freq) (0x7fffffff / (freq))
> +
> +/* Watchdog Feed register */
> +#define HW_WDFEED 0x08
> +
> +/* Watchdog Timer Value register */
> +#define HW_WDTV 0x0c
> +
> +#define ASM9260_WDT_DEFAULT_TIMEOUT 30
> +
> +enum asm9260_wdt_mode {
> + HW_RESET,
> + SW_RESET,
> + DEBUG,
> +};
> +
> +struct asm9260_wdt_priv {
> + struct device *dev;
> + struct watchdog_device wdd;
> + struct clk *clk;
> + struct clk *clk_ahb;
> + struct reset_control *rst;
> + struct notifier_block restart_handler;
> +
> + void __iomem *iobase;
> + int irq;
> + unsigned long wdt_freq;
> + enum asm9260_wdt_mode mode;
> +};
> +
> +static int asm9260_wdt_feed(struct watchdog_device *wdd)
> +{
> + struct asm9260_wdt_priv *priv = watchdog_get_drvdata(wdd);
> +
> + iowrite32(0xaa, priv->iobase + HW_WDFEED);
> + iowrite32(0x55, priv->iobase + HW_WDFEED);
> +
> + return 0;
> +}
> +
> +static unsigned int asm9260_wdt_gettimeleft(struct watchdog_device *wdd)
> +{
> + struct asm9260_wdt_priv *priv = watchdog_get_drvdata(wdd);
> + u32 counter;
> +
> + counter = ioread32(priv->iobase + HW_WDTV);
> +
> + return DIV_ROUND_CLOSEST(counter, priv->wdt_freq);
> +}
> +
> +static int asm9260_wdt_updatetimeout(struct watchdog_device *wdd)
> +{
> + struct asm9260_wdt_priv *priv = watchdog_get_drvdata(wdd);
> + u32 counter;
> +
> + counter = wdd->timeout * priv->wdt_freq;
> +
> + iowrite32(counter, priv->iobase + HW_WDTC);
> +
> + return 0;
> +}
> +
> +static int asm9260_wdt_enable(struct watchdog_device *wdd)
> +{
> + struct asm9260_wdt_priv *priv = watchdog_get_drvdata(wdd);
> + u32 mode = 0;
> +
> + if (priv->mode == HW_RESET)
> + mode = BM_MOD_WDRESET;
> +
> + iowrite32(BM_MOD_WDEN | mode, priv->iobase + HW_WDMOD);
> +
> + asm9260_wdt_updatetimeout(wdd);
> +
> + asm9260_wdt_feed(wdd);
> +
> + return 0;
> +}
> +
> +static int asm9260_wdt_disable(struct watchdog_device *wdd)
> +{
> + struct asm9260_wdt_priv *priv = watchdog_get_drvdata(wdd);
> +
> + /* The only way to disable WD is to reset it. */
> + reset_control_assert(priv->rst);
> + reset_control_deassert(priv->rst);
> +
> + return 0;
> +}
> +
> +static int asm9260_wdt_settimeout(struct watchdog_device *wdd, unsigned int to)
> +{
> + wdd->timeout = to;
> + asm9260_wdt_updatetimeout(wdd);
> +
> + return 0;
> +}
> +
> +static void asm9260_wdt_sys_reset(struct asm9260_wdt_priv *priv)
> +{
> + /* init WD if it was not started */
> +
> + iowrite32(BM_MOD_WDEN | BM_MOD_WDRESET, priv->iobase + HW_WDMOD);
> +
> + iowrite32(0xff, priv->iobase + HW_WDTC);
> + /* first pass correct sequence */
> + asm9260_wdt_feed(&priv->wdd);
> + /*
> + * Then write wrong pattern to the feed to trigger reset
> + * ASAP.
> + */
> + iowrite32(0xff, priv->iobase + HW_WDFEED);
> +
> + mdelay(1000);
> +}
> +
> +static irqreturn_t asm9260_wdt_irq(int irq, void *devid)
> +{
> + struct asm9260_wdt_priv *priv = devid;
> + u32 stat;
> +
> + stat = ioread32(priv->iobase + HW_WDMOD);
> + if (!(stat & BM_MOD_WDINT))
> + return IRQ_NONE;
> +
> + if (priv->mode == DEBUG)
> + dev_info(priv->dev, "Watchdog Timeout. Do nothing.\n");
> + else {
> + dev_info(priv->dev, "Watchdog Timeout. Doing SW Reset.\n");
> + asm9260_wdt_sys_reset(priv);
> + }
> +

coding style asks for { } in both branches of the if statement.

> + return IRQ_HANDLED;
> +}
> +
> +static int asm9260_restart_handler(struct notifier_block *this,
> + unsigned long mode, void *cmd)
> +{
> + struct asm9260_wdt_priv *priv =
> + container_of(this, struct asm9260_wdt_priv, restart_handler);
> +
> + asm9260_wdt_sys_reset(priv);
> +
> + return NOTIFY_DONE;
> +}
> +
> +static const struct watchdog_info asm9260_wdt_ident = {
> + .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING
> + | WDIOF_MAGICCLOSE,
> + .identity = "Alphascale asm9260 Watchdog",
> +};
> +
> +static struct watchdog_ops asm9260_wdt_ops = {
> + .owner = THIS_MODULE,
> + .start = asm9260_wdt_enable,
> + .stop = asm9260_wdt_disable,
> + .get_timeleft = asm9260_wdt_gettimeleft,
> + .ping = asm9260_wdt_feed,
> + .set_timeout = asm9260_wdt_settimeout,
> +};
> +
> +static int __init asm9260_wdt_get_dt_clks(struct asm9260_wdt_priv *priv)
> +{
> + int err;
> + unsigned long clk;
> +
> + priv->clk = devm_clk_get(priv->dev, "mod");
> + if (IS_ERR(priv->clk)) {
> + dev_err(priv->dev, "Failed to get \"mod\" clk\n");
> + return PTR_ERR(priv->clk);
> + }
> +
> + /* configure AHB clock */
> + priv->clk_ahb = devm_clk_get(priv->dev, "ahb");
> + if (IS_ERR(priv->clk_ahb)) {
> + dev_err(priv->dev, "Failed to get \"ahb\" clk\n");
> + return PTR_ERR(priv->clk_ahb);
> + }
> +
> + err = clk_prepare_enable(priv->clk_ahb);
> + if (err) {
> + dev_err(priv->dev, "Failed to enable ahb_clk!\n");
> + return err;
> + }
> +
> + err = clk_set_rate(priv->clk, CLOCK_FREQ);
> + if (err) {
> + clk_disable_unprepare(priv->clk_ahb);
> + dev_err(priv->dev, "Failed to set rate!\n");
> + return err;
> + }
> +
> + err = clk_prepare_enable(priv->clk);
> + if (err) {
> + clk_disable_unprepare(priv->clk_ahb);
> + dev_err(priv->dev, "Failed to enable clk!\n");
> + return err;
> + }
> +
> + /* wdt has internal divider */
> + clk = clk_get_rate(priv->clk);
> + if (!clk) {
> + clk_disable_unprepare(priv->clk);
> + clk_disable_unprepare(priv->clk_ahb);
> + dev_err(priv->dev, "Failed, clk is 0!\n");
> + return -EINVAL;
> + }
> +
> + priv->wdt_freq = clk / 2;
> +
> + return 0;
> +}
> +
> +static void __init asm9260_wdt_get_dt_mode(struct asm9260_wdt_priv *priv)
> +{
> + const char *tmp;
> + int ret;
> +
> + /* default mode */
> + priv->mode = HW_RESET;
> +
> + ret = of_property_read_string(priv->dev->of_node,
> + "alphascale,mode", &tmp);
> + if (ret < 0)
> + return;
> +
> + if (!strcmp(tmp, "hw"))
> + priv->mode = HW_RESET;
> + else if (!strcmp(tmp, "sw"))
> + priv->mode = SW_RESET;
> + else if (!strcmp(tmp, "debug"))
> + priv->mode = DEBUG;
> + else
> + dev_warn(priv->dev, "unknown reset-type: %s. Using default \"hw\" mode.",
> + tmp);
> +}
> +
> +static int __init asm9260_wdt_probe(struct platform_device *pdev)
> +{
> + struct asm9260_wdt_priv *priv;
> + struct watchdog_device *wdd;
> + struct resource *res;
> + int ret;
> +
> + priv = devm_kzalloc(&pdev->dev, sizeof(struct asm9260_wdt_priv),
> + GFP_KERNEL);
> + if (!priv)
> + return -ENOMEM;
> +
> + priv->dev = &pdev->dev;
> +
> + res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> + priv->iobase = devm_ioremap_resource(&pdev->dev, res);
> + if (IS_ERR(priv->iobase))
> + return PTR_ERR(priv->iobase);
> +
> + ret = asm9260_wdt_get_dt_clks(priv);
> + if (ret)
> + return ret;
> +
> + priv->rst = devm_reset_control_get(&pdev->dev, "wdt_rst");
> + if (IS_ERR(priv->rst))
> + return PTR_ERR(priv->rst);
> +
> + wdd = &priv->wdd;
> + wdd->info = &asm9260_wdt_ident;
> + wdd->ops = &asm9260_wdt_ops;
> + wdd->min_timeout = 1;
> + wdd->max_timeout = BM_WDTC_MAX(priv->wdt_freq);
> + wdd->parent = &pdev->dev;
> +
> + watchdog_set_drvdata(wdd, priv);
> +
> + /*
> + * If 'timeout-sec' unspecified in devicetree, assume a 30 second
> + * default, unless the max timeout is less than 30 seconds, then use
> + * the max instead.
> + */
> + wdd->timeout = ASM9260_WDT_DEFAULT_TIMEOUT;
> + watchdog_init_timeout(wdd, 0, &pdev->dev);
> +
> + asm9260_wdt_get_dt_mode(priv);
> +
> + if (priv->mode != HW_RESET)
> + priv->irq = platform_get_irq(pdev, 0);
> +
> + if (priv->irq > 0) {
> + /*
> + * Not all supported platforms specify an interrupt for the
> + * watchdog, so let's make it optional.
> + */
> + ret = devm_request_irq(&pdev->dev, priv->irq,
> + asm9260_wdt_irq, IRQF_SHARED,
> + pdev->name, priv);
> + if (ret < 0)
> + dev_warn(&pdev->dev, "failed to request IRQ\n");
> + }
> +
> + ret = watchdog_register_device(wdd);
> + if (ret)
> + goto clk_off;
> +
> + platform_set_drvdata(pdev, priv);
> +
> + priv->restart_handler.notifier_call = asm9260_restart_handler;
> + priv->restart_handler.priority = 128;
> + ret = register_restart_handler(&priv->restart_handler);
> + if (ret)
> + dev_warn(&pdev->dev, "cannot register restart handler\n");
> +
> + dev_info(&pdev->dev, "Watchdog enabled (to=%d, mode=%d)\n",

Wonder who will know what "to" means. How about "timeout" ?

Also, would it possibly make more sense to spell out the mode ?
Users won't know what 0/1/2 means.

> + wdd->timeout, priv->mode);
> + return 0;
> +
> +clk_off:
> + clk_disable_unprepare(priv->clk);
> + clk_disable_unprepare(priv->clk_ahb);

The interrupt is still enabled here. Is this safe ?

> + return ret;
> +}
> +
> +static void asm9260_wdt_shutdown(struct platform_device *pdev)
> +{
> + struct asm9260_wdt_priv *priv = platform_get_drvdata(pdev);
> +
> + asm9260_wdt_disable(&priv->wdd);
> +}
> +
> +static int __exit asm9260_wdt_remove(struct platform_device *pdev)
> +{
> + struct asm9260_wdt_priv *priv = platform_get_drvdata(pdev);
> +
> + asm9260_wdt_disable(&priv->wdd);
> +
> + unregister_restart_handler(&priv->restart_handler);

watchdog_unregister_device() ?

> + clk_disable_unprepare(priv->clk);
> + clk_disable_unprepare(priv->clk_ahb);

The interrupt is still enabled here, and the handler may be called
since it is a shared interrupt. Is this safe ?

> +
> + return 0;
> +}
> +
> +static const struct of_device_id asm9260_wdt_of_match[] = {
> + { .compatible = "alphascale,asm9260-wdt"},
> + {},
> +};
> +MODULE_DEVICE_TABLE(of, asm9260_wdt_of_match);
> +
> +static struct platform_driver asm9260_wdt_driver = {
> + .driver = {
> + .name = "asm9260-wdt",
> + .owner = THIS_MODULE,
> + .of_match_table = asm9260_wdt_of_match,
> + },
> + .probe = asm9260_wdt_probe,
> + .remove = asm9260_wdt_remove,
> + .shutdown = asm9260_wdt_shutdown,
> +};
> +module_platform_driver(asm9260_wdt_driver);
> +
> +MODULE_DESCRIPTION("asm9260 WatchDog Timer Driver");
> +MODULE_AUTHOR("Oleksij Rempel <linux@rempel-privat.de>");
> +MODULE_LICENSE("GPL");
>