Hi Guenter Roeck,
Thanks for the feedback.
> Subject: Re: [RFC 4/4] watchdog: Add Watchdog Timer driver for RZ/G2L
>
> On 11/4/21 9:08 AM, Biju Das wrote:
> > Add Watchdog Timer driver for RZ/G2L SoC.
> >
> > WDT IP block supports normal watchdog timer function and reset request
> > function due to CPU parity error.
> >
> > This driver currently supports normal watchdog timer function and
> > later will add support for reset request function due to CPU parity
> > error.
> >
> > Signed-off-by: Biju Das <biju.das.jz@xxxxxxxxxxxxxx>
> > ---
> > drivers/watchdog/Kconfig | 8 +
> > drivers/watchdog/Makefile | 1 +
> > drivers/watchdog/rzg2l_wdt.c | 281 +++++++++++++++++++++++++++++++++++
> > 3 files changed, 290 insertions(+)
> > create mode 100644 drivers/watchdog/rzg2l_wdt.c
> >
> > diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig index
> > bf59faeb3de1..34da309a7afd 100644
> > --- a/drivers/watchdog/Kconfig
> > +++ b/drivers/watchdog/Kconfig
> > @@ -895,6 +895,14 @@ config RENESAS_RZAWDT
> > This driver adds watchdog support for the integrated watchdogs in
> the
> > Renesas RZ/A SoCs. These watchdogs can be used to reset a system.
> >
> > +config RENESAS_RZG2LWDT
> > + tristate "Renesas RZ/G2L WDT Watchdog"
> > + depends on ARCH_RENESAS || COMPILE_TEST
> > + select WATCHDOG_CORE
> > + help
> > + This driver adds watchdog support for the integrated watchdogs in
> the
> > + Renesas RZ/G2L SoCs. These watchdogs can be used to reset a
> system.
> > +
> > config ASPEED_WATCHDOG
> > tristate "Aspeed BMC watchdog support"
> > depends on ARCH_ASPEED || COMPILE_TEST diff --git
> > a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile index
> > 1bd2d6f37c53..e7e8ce546814 100644
> > --- a/drivers/watchdog/Makefile
> > +++ b/drivers/watchdog/Makefile
> > @@ -85,6 +85,7 @@ obj-$(CONFIG_LPC18XX_WATCHDOG) += lpc18xx_wdt.o
> > obj-$(CONFIG_BCM7038_WDT) += bcm7038_wdt.o
> > obj-$(CONFIG_RENESAS_WDT) += renesas_wdt.o
> > obj-$(CONFIG_RENESAS_RZAWDT) += rza_wdt.o
> > +obj-$(CONFIG_RENESAS_RZG2LWDT) += rzg2l_wdt.o
> > obj-$(CONFIG_ASPEED_WATCHDOG) += aspeed_wdt.o
> > obj-$(CONFIG_STM32_WATCHDOG) += stm32_iwdg.o
> > obj-$(CONFIG_UNIPHIER_WATCHDOG) += uniphier_wdt.o diff --git
> > a/drivers/watchdog/rzg2l_wdt.c b/drivers/watchdog/rzg2l_wdt.c new file
> > mode 100644 index 000000000000..a477f7792be8
> > --- /dev/null
> > +++ b/drivers/watchdog/rzg2l_wdt.c
> > @@ -0,0 +1,281 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * Renesas RZ/G2L WDT Watchdog Driver
> > + *
> > + * Copyright (C) 2021 Renesas Electronics Corporation */ #include
> > +<linux/bitops.h> #include <linux/clk.h> #include <linux/delay.h>
> > +#include <linux/io.h> #include <linux/kernel.h> #include
> > +<linux/module.h> #include <linux/of.h> #include
> > +<linux/platform_device.h> #include <linux/pm_runtime.h> #include
> > +<linux/reset.h> #include <linux/watchdog.h>
> > +
> > +#define WDTCNT 0x00
> > +#define WDTSET 0x04
> > +#define WDTTIM 0x08
> > +#define WDTINT 0x0C
> > +#define WDTCNT_WDTEN BIT(0)
> > +#define WDTINT_INTDISP BIT(0)
> > +
> > +#define WDT_DEFAULT_TIMEOUT 60U
> > +
> > +/* Setting period time register only 12 bit set in WDTSET[31:20] */
> > +#define WDTSET_COUNTER_MASK (0xFFF00000)
> > +#define WDTSET_COUNTER_VAL(f) ((f) << 20)
> > +
> > +#define F2CYCLE_NSEC(f) (1000000000 / (f))
> > +#define WDT_CYCLE_MSEC(f, wdttime) ((1024 * 1024 * (((u64)wdttime)
> + 1)) / \
> > + ((f) / 1000000))
> > +
> > +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) ")");
> > +
> > +struct rzg2l_wdt_priv {
> > + void __iomem *base;
> > + struct watchdog_device wdev;
> > + struct reset_control *rstc;
> > + unsigned long osc_clk_rate;
> > + unsigned long pclk_rate;
>
> pclk_rate is only used in the probe function and thus not needed here.
OK. It is not needed here.
> > + unsigned long delay;
> > +};
> > +
> > +static void rzg2l_wdt_wait_delay(struct rzg2l_wdt_priv *priv) {
> > + /* delay timer when change the setting register */
> > + ndelay(priv->delay);
> > +}
> > +
> > +static int rzg2l_wdt_write(struct rzg2l_wdt_priv *priv, u32 val,
> > +unsigned int reg) {
> > + int i;
> > +
> > + if (reg == WDTSET)
> > + val &= WDTSET_COUNTER_MASK;
> > +
> > + writel_relaxed(val, priv->base + reg);
> > +
> > + for (i = 0; i < 1000; i++) {
> > + if (readl_relaxed(priv->base + reg) == val)
> > + return 0;
> > + rzg2l_wdt_wait_delay(priv);
> > + }
>
> This needs some explanation. Under which circumstances does the chip
> refuse to update the register ?
Each register other than the WDT interrupt control register (WDTINT)
is always synchronized with WDTn_CLK (n =0, 1, 2) at regular intervals.
The timing at which the written data is reflected in the watchdog timer
operation is 6 × P0ϕ +9 × OSCCLK).
I will make this function as void and will remove all the occurrences
of rzg2l_wdt_wait_delay.
static void rzg2l_wdt_write(struct rzg2l_wdt_priv *priv, u32 val, unsigned int reg)
{
if (reg == WDTSET)
val &= WDTSET_COUNTER_MASK;
writel_relaxed(val, priv->base + reg);
/* Registers other than the WDTINT is always synchronized with WDT_CLK */
if (reg != WDTINT)
rzg2l_wdt_wait_delay(priv);
}
>
> > +
> > + return -ETIMEDOUT;
> > +}
> > +
> > +static int rzg2l_wdt_init_timeout(struct watchdog_device *wdev) {
> > + struct rzg2l_wdt_priv *priv = watchdog_get_drvdata(wdev);
> > + u32 time_out;
> > +
> > + /* Clear Lapsed Time Register and clear Interrupt */
> > + rzg2l_wdt_write(priv, WDTINT_INTDISP, WDTINT);
> > + /* Delay timer before setting watchdog counter*/
> > + rzg2l_wdt_wait_delay(priv);
> > + /* 2 consecutive overflow cycle needed to trigger reset */
> > + time_out = (wdev->timeout / 2 * 1000000) / WDT_CYCLE_MSEC(priv-
> >osc_clk_rate, 0);
> > + rzg2l_wdt_write(priv, WDTSET_COUNTER_VAL(time_out), WDTSET);
> > +
> > + return 0;
>
> rzg2l_wdt_write() returns an error which is ignored. This functions always
> returns 0, ignoring any errors, but then the calling code ignores the
> return value anyway. This doesn't make sense, or at least it is very
> inconsistent.
> Either check for errors and handle them, or if errors are ignored anyway
> there is no point of checking.
OK. I will make this void function as well, as rzg2l_wdt_write will be void
function as explained above.
>
> > +}
> > +
> > +static int rzg2l_wdt_start(struct watchdog_device *wdev) {
> > + struct rzg2l_wdt_priv *priv = watchdog_get_drvdata(wdev);
> > +
> > + reset_control_deassert(priv->rstc);
> > + pm_runtime_get_sync(wdev->parent);
> > +
> > + /* Initialize time out */
> > + rzg2l_wdt_init_timeout(wdev);
> > +
> > + rzg2l_wdt_wait_delay(priv);
> > + /* Initialize watchdog counter register */
> > + rzg2l_wdt_write(priv, 0, WDTTIM);
> > +
> > + /* Enable watchdog timer*/
> > + rzg2l_wdt_write(priv, WDTCNT_WDTEN, WDTCNT);
> > +
> > + set_bit(WDOG_HW_RUNNING, &wdev->status);
>
> This is only needed if the watchdog can not be stopped, which does not
> appear to be the case here.
OK. I will remove this, As I can stop the watchdog by putting the module
to reset state.
>
> > +
> > + return 0;
> > +}
> > +
> > +static int rzg2l_wdt_stop(struct watchdog_device *wdev) {
> > + struct rzg2l_wdt_priv *priv = watchdog_get_drvdata(wdev);
> > +
> > + pm_runtime_put(wdev->parent);
> > + reset_control_assert(priv->rstc);
> > +
> > + return 0;
> > +}
> > +
> > +static int rzg2l_wdt_restart(struct watchdog_device *wdev,
> > + unsigned long action, void *data) {
> > + struct rzg2l_wdt_priv *priv = watchdog_get_drvdata(wdev);
> > +
> > + /* Reset the module before we modify any register */
> > + reset_control_reset(priv->rstc);
> > + pm_runtime_get_sync(wdev->parent);
> > +
> > + /* smallest counter value to reboot soon */
> > + rzg2l_wdt_write(priv, WDTSET_COUNTER_VAL(1), WDTSET);
> > +
> > + rzg2l_wdt_wait_delay(priv);
> > + /* Enable watchdog timer*/
> > + rzg2l_wdt_write(priv, WDTCNT_WDTEN, WDTCNT);
> > +
> > + return 0;
> > +}
> > +
> > +static const struct watchdog_info rzg2l_wdt_ident = {
> > + .options = WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING |
> WDIOF_SETTIMEOUT,
> > + .identity = "Renesas RZ/G2L WDT Watchdog", };
> > +
> > +static int rzg2l_wdt_ping(struct watchdog_device *wdev) {
> > + struct rzg2l_wdt_priv *priv = watchdog_get_drvdata(wdev);
> > +
> > + rzg2l_wdt_write(priv, WDTINT_INTDISP, WDTINT);
> > +
> > + return 0;
> > +}
> > +
> > +static const struct watchdog_ops rzg2l_wdt_ops = {
> > + .owner = THIS_MODULE,
> > + .start = rzg2l_wdt_start,
> > + .stop = rzg2l_wdt_stop,
> > + .ping = rzg2l_wdt_ping,
> > + .restart = rzg2l_wdt_restart,
> > +};
> > +
> > +static void rzg2l_wdt_reset_assert_clock_disable(void *data) {
> > + struct rzg2l_wdt_priv *priv = watchdog_get_drvdata(data);
> > +
> > + reset_control_assert(priv->rstc);
> > +}
> > +
> > +static int rzg2l_wdt_probe(struct platform_device *pdev) {
> > + struct device *dev = &pdev->dev;
> > + struct rzg2l_wdt_priv *priv;
> > + struct clk *wdt_clk;
> > + int ret;
> > +
> > + priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
> > + if (!priv)
> > + return -ENOMEM;
> > +
> > + priv->base = devm_platform_ioremap_resource(pdev, 0);
> > + if (IS_ERR(priv->base))
> > + return PTR_ERR(priv->base);
> > +
> > + /* Get watchdog main clock */
> > + wdt_clk = devm_clk_get(&pdev->dev, "oscclk");
> > + if (IS_ERR(wdt_clk))
> > + return dev_err_probe(&pdev->dev, PTR_ERR(wdt_clk), "no
> oscclk");
> > +
> > + priv->osc_clk_rate = clk_get_rate(wdt_clk);
> > + if (!priv->osc_clk_rate)
> > + return dev_err_probe(&pdev->dev, -EINVAL, "oscclk rate is 0");
> > +
> > + /* Get Peripheral clock */
> > + wdt_clk = devm_clk_get(&pdev->dev, "pclk");
> > + if (IS_ERR(wdt_clk))
> > + return dev_err_probe(&pdev->dev, PTR_ERR(wdt_clk), "no pclk");
> > +
> > + priv->pclk_rate = clk_get_rate(wdt_clk);
> > + if (!priv->pclk_rate)
> > + return dev_err_probe(&pdev->dev, -EINVAL, "pclk rate is 0");
> > +
> > + priv->delay = F2CYCLE_NSEC(priv->osc_clk_rate) * 6 +
> > +F2CYCLE_NSEC(priv->pclk_rate) * 9;
> > +
> > + priv->rstc = devm_reset_control_get(&pdev->dev, NULL);
> > + if (IS_ERR(priv->rstc))
> > + return dev_err_probe(&pdev->dev, PTR_ERR(priv->rstc),
> > + "failed to get cpg reset");
> > +
> > + reset_control_deassert(priv->rstc);
> > + ret = devm_add_action_or_reset(&pdev->dev,
> > + rzg2l_wdt_reset_assert_clock_disable,
> > + &priv->wdev);
> > + if (ret < 0)
> > + return dev_err_probe(&pdev->dev, ret, "failed to get reset");
> > +
> > + pm_runtime_enable(&pdev->dev);
> > + ret = pm_runtime_resume_and_get(&pdev->dev);
> > + if (ret < 0) {
> > + dev_err(dev, "pm_runtime_resume_and_get failed");
> > + goto out_pm_get;
> > + }
> > +
> > + priv->wdev.info = &rzg2l_wdt_ident;
> > + priv->wdev.ops = &rzg2l_wdt_ops;
> > + priv->wdev.parent = dev;
> > + priv->wdev.min_timeout = 1;
> > + priv->wdev.max_timeout = WDT_CYCLE_MSEC(priv->osc_clk_rate, 0xfff);
> > + priv->wdev.timeout = WDT_DEFAULT_TIMEOUT;
> > +
> > + platform_set_drvdata(pdev, priv);
>
> Is this used anywhere ?
Not used. It is supposed to use in remove function, for unregistering
watchdog device(in case, if we use watchdog_register_device)
But I am planning to use devm_watchdog_register_device.
So will remove both platform_set_drvdata and remove function.
>
> > + watchdog_set_drvdata(&priv->wdev, priv);
> > + watchdog_set_nowayout(&priv->wdev, nowayout);
> > + watchdog_set_restart_priority(&priv->wdev, 0);
>
> 0 is the default restart priority (ie this is a reset of last resort).
> It does not have to be set explicitly.
Agreed. Will remove this.
>
> > + watchdog_stop_on_unregister(&priv->wdev);
> > +
> > + ret = watchdog_init_timeout(&priv->wdev, 0, dev);
> > + if (ret)
> > + dev_warn(dev, "Specified timeout invalid, using default");
> > +
> > + ret = devm_watchdog_register_device(&pdev->dev, &priv->wdev);
> > + if (ret < 0)
> > + goto out_pm_disable;
> > +
> > + return 0;
> > +
> > +out_pm_disable:
> > + pm_runtime_put(dev);
> > +out_pm_get:
> > + pm_runtime_disable(dev);
> > +
> > + return ret;
> > +}
> > +
> > +static int rzg2l_wdt_remove(struct platform_device *pdev) {
> > + pm_runtime_put(&pdev->dev);
> > + pm_runtime_disable(&pdev->dev);
> > +
>
> This is the wrong order. The watchdog device has to be removed first,
> meaning you can not use devm_watchdog_register_device(), or you would have
> to use devm_add_action_or_reset() to call the runtime pm put/disable
> functions.
OK, will use devm_watchdog_register_device and will put runtime pm put/disable
to devm_add_action_or_reset. After this remove function is empty, and will remove it.
Regards,
Biju
>
> > + return 0;
> > +}
> > +
> > +static const struct of_device_id rzg2l_wdt_ids[] = {
> > + { .compatible = "renesas,rzg2l-wdt", },
> > + { /* sentinel */ }
> > +};
> > +MODULE_DEVICE_TABLE(of, rzg2l_wdt_ids);
> > +
> > +static struct platform_driver rzg2l_wdt_driver = {
> > + .driver = {
> > + .name = "rzg2l_wdt",
> > + .of_match_table = rzg2l_wdt_ids,
> > + },
> > + .probe = rzg2l_wdt_probe,
> > + .remove = rzg2l_wdt_remove,
> > +};
> > +module_platform_driver(rzg2l_wdt_driver);
> > +
> > +MODULE_DESCRIPTION("Renesas RZ/G2L WDT Watchdog Driver");
> > +MODULE_AUTHOR("Biju Das <biju.das.jz@xxxxxxxxxxxxxx>");
> > +MODULE_LICENSE("GPL v2");
> >
