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SubjectRe: [PATCH V3 2/4] watchdog: Add i.MX7ULP watchdog support
On Tue, Aug 20, 2019 at 10:07:56PM -0400, Anson Huang wrote:
> The i.MX7ULP Watchdog Timer (WDOG) module is an independent timer
> that is available for system use.
> It provides a safety feature to ensure that software is executing
> as planned and that the CPU is not stuck in an infinite loop or
> executing unintended code. If the WDOG module is not serviced
> (refreshed) within a certain period, it resets the MCU.
>
> Add driver support for i.MX7ULP watchdog.
>
> Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
> ---
> Changes since V2:
> - add devm_add_action_or_reset to disable clk for remove action.
> ---
> drivers/watchdog/Kconfig | 13 +++
> drivers/watchdog/Makefile | 1 +
> drivers/watchdog/imx7ulp_wdt.c | 246 +++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 260 insertions(+)
> create mode 100644 drivers/watchdog/imx7ulp_wdt.c
>
> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
> index a8f5c81..d68e5b5 100644
> --- a/drivers/watchdog/Kconfig
> +++ b/drivers/watchdog/Kconfig
> @@ -724,6 +724,19 @@ config IMX_SC_WDT
> To compile this driver as a module, choose M here: the
> module will be called imx_sc_wdt.
>
> +config IMX7ULP_WDT
> + tristate "IMX7ULP Watchdog"
> + depends on ARCH_MXC || COMPILE_TEST
> + select WATCHDOG_CORE
> + help
> + This is the driver for the hardware watchdog on the Freescale
> + IMX7ULP and later processors. If you have one of these
> + processors and wish to have watchdog support enabled,
> + say Y, otherwise say N.
> +
> + To compile this driver as a module, choose M here: the
> + module will be called imx7ulp_wdt.
> +
> config UX500_WATCHDOG
> tristate "ST-Ericsson Ux500 watchdog"
> depends on MFD_DB8500_PRCMU
> diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
> index b5a0aed..2ee352b 100644
> --- a/drivers/watchdog/Makefile
> +++ b/drivers/watchdog/Makefile
> @@ -67,6 +67,7 @@ obj-$(CONFIG_TS4800_WATCHDOG) += ts4800_wdt.o
> obj-$(CONFIG_TS72XX_WATCHDOG) += ts72xx_wdt.o
> obj-$(CONFIG_IMX2_WDT) += imx2_wdt.o
> obj-$(CONFIG_IMX_SC_WDT) += imx_sc_wdt.o
> +obj-$(CONFIG_IMX7ULP_WDT) += imx7ulp_wdt.o
> obj-$(CONFIG_UX500_WATCHDOG) += ux500_wdt.o
> obj-$(CONFIG_RETU_WATCHDOG) += retu_wdt.o
> obj-$(CONFIG_BCM2835_WDT) += bcm2835_wdt.o
> diff --git a/drivers/watchdog/imx7ulp_wdt.c b/drivers/watchdog/imx7ulp_wdt.c
> new file mode 100644
> index 0000000..5d37957
> --- /dev/null
> +++ b/drivers/watchdog/imx7ulp_wdt.c
> @@ -0,0 +1,246 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright 2019 NXP.
> + */
> +
> +#include <linux/clk.h>
> +#include <linux/init.h>
> +#include <linux/io.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/platform_device.h>
> +#include <linux/reboot.h>
> +#include <linux/watchdog.h>
> +
> +#define WDOG_CS 0x0
> +#define WDOG_CS_CMD32EN BIT(13)
> +#define WDOG_CS_ULK BIT(11)
> +#define WDOG_CS_RCS BIT(10)
> +#define WDOG_CS_EN BIT(7)
> +#define WDOG_CS_UPDATE BIT(5)
> +
> +#define WDOG_CNT 0x4
> +#define WDOG_TOVAL 0x8
> +
> +#define REFRESH_SEQ0 0xA602
> +#define REFRESH_SEQ1 0xB480
> +#define REFRESH ((REFRESH_SEQ1 << 16) | REFRESH_SEQ0)
> +
> +#define UNLOCK_SEQ0 0xC520
> +#define UNLOCK_SEQ1 0xD928
> +#define UNLOCK ((UNLOCK_SEQ1 << 16) | UNLOCK_SEQ0)
> +
> +#define DEFAULT_TIMEOUT 60
> +#define MAX_TIMEOUT 128
> +
> +static bool nowayout = WATCHDOG_NOWAYOUT;
> +module_param(nowayout, bool, 0000);
> +MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
> + __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
> +
> +struct imx7ulp_wdt_device {
> + struct notifier_block restart_handler;
> + struct watchdog_device wdd;
> + void __iomem *base;
> + struct clk *clk;
> + int rate;
> +};
> +
> +static inline void imx7ulp_wdt_enable(void __iomem *base, bool enable)
> +{
> + u32 val = readl(base + WDOG_CS);
> +
> + writel(UNLOCK, base + WDOG_CNT);
> + if (enable)
> + writel(val | WDOG_CS_EN, base + WDOG_CS);
> + else
> + writel(val & ~WDOG_CS_EN, base + WDOG_CS);
> +}
> +
> +static inline bool imx7ulp_wdt_is_enabled(void __iomem *base)
> +{
> + u32 val = readl(base + WDOG_CS);
> +
> + return val & WDOG_CS_EN;
> +}
> +
> +static int imx7ulp_wdt_ping(struct watchdog_device *wdog)
> +{
> + struct imx7ulp_wdt_device *wdt = watchdog_get_drvdata(wdog);
> +
> + writel(REFRESH, wdt->base + WDOG_CNT);
> +
> + return 0;
> +}
> +
> +static int imx7ulp_wdt_start(struct watchdog_device *wdog)
> +{
> + struct imx7ulp_wdt_device *wdt = watchdog_get_drvdata(wdog);
> +
> + imx7ulp_wdt_enable(wdt->base, true);
> +
> + return 0;
> +}
> +
> +static int imx7ulp_wdt_stop(struct watchdog_device *wdog)
> +{
> + struct imx7ulp_wdt_device *wdt = watchdog_get_drvdata(wdog);
> +
> + imx7ulp_wdt_enable(wdt->base, false);
> +
> + return 0;
> +}
> +
> +static int imx7ulp_wdt_set_timeout(struct watchdog_device *wdog,
> + unsigned int timeout)
> +{
> + struct imx7ulp_wdt_device *wdt = watchdog_get_drvdata(wdog);
> + u32 val = wdt->rate * timeout;
> +
> + writel(UNLOCK, wdt->base + WDOG_CNT);
> + writel(val, wdt->base + WDOG_TOVAL);
> +
> + wdog->timeout = timeout;
> +
> + return 0;
> +}
> +
> +static const struct watchdog_ops imx7ulp_wdt_ops = {
> + .owner = THIS_MODULE,
> + .start = imx7ulp_wdt_start,
> + .stop = imx7ulp_wdt_stop,
> + .ping = imx7ulp_wdt_ping,
> + .set_timeout = imx7ulp_wdt_set_timeout,
> +};
> +
> +static const struct watchdog_info imx7ulp_wdt_info = {
> + .identity = "i.MX7ULP watchdog timer",
> + .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
> + WDIOF_MAGICCLOSE,
> +};
> +
> +static inline void imx7ulp_wdt_init(void __iomem *base, unsigned int timeout)
> +{
> + u32 val;
> +
> + /* unlock the wdog for reconfiguration */
> + writel_relaxed(UNLOCK_SEQ0, base + WDOG_CNT);
> + writel_relaxed(UNLOCK_SEQ1, base + WDOG_CNT);
> +
> + /* set an initial timeout value in TOVAL */
> + writel(timeout, base + WDOG_TOVAL);
> + /* enable 32bit command sequence and reconfigure */
> + val = BIT(13) | BIT(8) | BIT(5);
> + writel(val, base + WDOG_CS);
> +}
> +
> +static void imx7ulp_wdt_action(void *data)
> +{
> + struct imx7ulp_wdt_device *imx7ulp_wdt = data;
> +
> + clk_disable_unprepare(imx7ulp_wdt->clk);

If you had passed imx7ulp_wdt->clk as parameter, the dereference here
would not be necessary.

> +}
> +
> +static int imx7ulp_wdt_probe(struct platform_device *pdev)
> +{
> + struct imx7ulp_wdt_device *imx7ulp_wdt;
> + struct device *dev = &pdev->dev;
> + struct watchdog_device *wdog;
> + int ret;
> +
> + imx7ulp_wdt = devm_kzalloc(dev, sizeof(*imx7ulp_wdt), GFP_KERNEL);
> + if (!imx7ulp_wdt)
> + return -ENOMEM;
> +
> + platform_set_drvdata(pdev, imx7ulp_wdt);
> +
> + imx7ulp_wdt->base = devm_platform_ioremap_resource(pdev, 0);
> + if (IS_ERR(imx7ulp_wdt->base))
> + return PTR_ERR(imx7ulp_wdt->base);
> +
> + imx7ulp_wdt->clk = devm_clk_get(dev, NULL);
> + if (IS_ERR(imx7ulp_wdt->clk)) {
> + dev_err(dev, "Failed to get watchdog clock\n");
> + return PTR_ERR(imx7ulp_wdt->clk);
> + }
> +
> + ret = clk_prepare_enable(imx7ulp_wdt->clk);
> + if (ret)
> + return ret;
> +
> + ret = devm_add_action_or_reset(dev, imx7ulp_wdt_action, imx7ulp_wdt);
> + if (ret)
> + return ret;
> +
> + imx7ulp_wdt->rate = 1000;

I forgot to ask (sorry, I had noticed, but I guess I forgot).

Why not clk_get_rate() ? If the clock rate is fixed, why bother with a 'rate'
variable ? You could use a constant instead whereever it is used.

Thanks
Guenter

> + wdog = &imx7ulp_wdt->wdd;
> + wdog->info = &imx7ulp_wdt_info;
> + wdog->ops = &imx7ulp_wdt_ops;
> + wdog->min_timeout = 1;
> + wdog->max_timeout = MAX_TIMEOUT;
> + wdog->parent = dev;
> + wdog->timeout = DEFAULT_TIMEOUT;
> +
> + watchdog_init_timeout(wdog, 0, dev);
> + watchdog_stop_on_reboot(wdog);
> + watchdog_stop_on_unregister(wdog);
> + watchdog_set_drvdata(wdog, imx7ulp_wdt);
> + imx7ulp_wdt_init(imx7ulp_wdt->base, wdog->timeout * imx7ulp_wdt->rate);
> +
> + return devm_watchdog_register_device(dev, wdog);
> +}
> +
> +static int __maybe_unused imx7ulp_wdt_suspend(struct device *dev)
> +{
> + struct imx7ulp_wdt_device *imx7ulp_wdt = dev_get_drvdata(dev);
> +
> + if (watchdog_active(&imx7ulp_wdt->wdd))
> + imx7ulp_wdt_stop(&imx7ulp_wdt->wdd);
> +
> + clk_disable_unprepare(imx7ulp_wdt->clk);
> +
> + return 0;
> +}
> +
> +static int __maybe_unused imx7ulp_wdt_resume(struct device *dev)
> +{
> + struct imx7ulp_wdt_device *imx7ulp_wdt = dev_get_drvdata(dev);
> + u32 timeout = imx7ulp_wdt->wdd.timeout * imx7ulp_wdt->rate;
> + int ret;
> +
> + ret = clk_prepare_enable(imx7ulp_wdt->clk);
> + if (ret)
> + return ret;
> +
> + if (imx7ulp_wdt_is_enabled(imx7ulp_wdt->base))
> + imx7ulp_wdt_init(imx7ulp_wdt->base, timeout);
> +
> + if (watchdog_active(&imx7ulp_wdt->wdd))
> + imx7ulp_wdt_start(&imx7ulp_wdt->wdd);
> +
> + return 0;
> +}
> +
> +static SIMPLE_DEV_PM_OPS(imx7ulp_wdt_pm_ops, imx7ulp_wdt_suspend,
> + imx7ulp_wdt_resume);
> +
> +static const struct of_device_id imx7ulp_wdt_dt_ids[] = {
> + { .compatible = "fsl,imx7ulp-wdt", },
> + { /* sentinel */ }
> +};
> +MODULE_DEVICE_TABLE(of, imx7ulp_wdt_dt_ids);
> +
> +static struct platform_driver imx7ulp_wdt_driver = {
> + .probe = imx7ulp_wdt_probe,
> + .driver = {
> + .name = "imx7ulp-wdt",
> + .pm = &imx7ulp_wdt_pm_ops,
> + .of_match_table = imx7ulp_wdt_dt_ids,
> + },
> +};
> +module_platform_driver(imx7ulp_wdt_driver);
> +
> +MODULE_AUTHOR("Anson Huang <Anson.Huang@nxp.com>");
> +MODULE_DESCRIPTION("Freescale i.MX7ULP watchdog driver");
> +MODULE_LICENSE("GPL v2");
> --
> 2.7.4
>

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