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Message-ID: <CAMuHMdV4PM9gC2wDZJKXKUt7AG2wS+adub=M+d0BrOedZ9ENPg@mail.gmail.com>
Date: Wed, 9 Feb 2022 09:28:42 +0100
From: Geert Uytterhoeven <geert@...ux-m68k.org>
To: Jean-Jacques Hiblot <jjhiblot@...phandler.com>
Cc: Linux-Renesas <linux-renesas-soc@...r.kernel.org>,
Wim Van Sebroeck <wim@...ux-watchdog.org>,
Guenter Roeck <linux@...ck-us.net>,
Phil Edworthy <phil.edworthy@...esas.com>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Linux Watchdog Mailing List <linux-watchdog@...r.kernel.org>
Subject: Re: [PATCH v2 5/6] watchdog: Add Renesas RZ/N1 Watchdog driver
Hi Jean-Jacques,
On Tue, Feb 8, 2022 at 7:35 PM Jean-Jacques Hiblot
<jjhiblot@...phandler.com> wrote:
> From: Phil Edworthy <phil.edworthy@...esas.com>
>
> This is a driver for the standard WDT on the RZ/N1 devices. This WDT has
> very limited timeout capabilities. However, it can reset the device.
> To do so, the corresponding bits in the SysCtrl RSTEN register need to
> be enabled. This is not done by this driver.
>
> Signed-off-by: Phil Edworthy <phil.edworthy@...esas.com>
> Signed-off-by: Jean-Jacques Hiblot <jjhiblot@...phandler.com>
Thanks for your patch!
> --- /dev/null
> +++ b/drivers/watchdog/rzn1_wdt.c
> @@ -0,0 +1,208 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Renesas RZ/N1 Watchdog timer.
> + * This is a 12-bit timer driver from a (62.5/16384) MHz clock. It can't even
> + * cope with 2 seconds.
> + *
> + * Copyright 2018 Renesas Electronics Europe Ltd.
> + *
> + * Derived from Ralink RT288x watchdog timer.
> + */
> +
> +#include <linux/clk.h>
> +#include <linux/interrupt.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/of_address.h>
> +#include <linux/of_irq.h>
> +#include <linux/platform_device.h>
> +#include <linux/watchdog.h>
> +
> +#define DEFAULT_TIMEOUT 60
> +
> +#define RZN1_WDT_RETRIGGER 0x0
> +#define RZN1_WDT_RETRIGGER_RELOAD_VAL 0
> +#define RZN1_WDT_RETRIGGER_RELOAD_VAL_MASK 0xfff
> +#define RZN1_WDT_RETRIGGER_PRESCALE BIT(12)
> +#define RZN1_WDT_RETRIGGER_ENABLE BIT(13)
> +#define RZN1_WDT_RETRIGGER_WDSI (0x2 << 14)
> +
> +#define RZN1_WDT_PRESCALER 16384
> +#define RZN1_WDT_MAX 4095
> +
> +struct rzn1_watchdog {
> + struct watchdog_device wdt;
> + void __iomem *base;
> + unsigned long clk_rate;
> +};
> +
> +#define to_rzn1_watchdog(_ptr) \
> + container_of(_ptr, struct rzn1_watchdog, wdt)
> +
> +static inline uint32_t get_max_heart_beat(uint32_t clk_rate)
unsigned long clk_rate
> +{
> + return (RZN1_WDT_MAX * RZN1_WDT_PRESCALER) / (clk_rate / 1000);
Is clk_rate always a multiple of 1000? If not, you want to reorder
this to avoid losing precision.
> +}
> +static inline uint32_t compute_reload_value(uint32_t tick_ms, uint32_t clk)
unsigned long clk_rate
> +{
> + return (tick_ms * (clk / 1000)) / RZN1_WDT_PRESCALER;
Likewise.
> +}
> +static int rzn1_wdt_probe(struct platform_device *pdev)
> +{
> + struct device *dev = &pdev->dev;
> + struct rzn1_watchdog *wdt;
> + struct device_node *np = dev->of_node;
> + struct clk *clk;
> + int ret;
> + int irq;
> +
> + wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
> + if (!wdt)
> + return -ENOMEM;
> +
> + wdt->wdt = rzn1_wdt;
> + wdt->wdt.parent = dev;
> +
> + wdt->base = devm_platform_ioremap_resource(pdev, 0);
> + if (IS_ERR(wdt->base))
> + return PTR_ERR(wdt->base);
> +
> + irq = platform_get_irq(pdev, 0);
> + if (irq < 0) {
> + dev_err(dev, "failed to get the irq\n");
No need to print a message, platform_get_irq() already does that.
> + return irq;
> + }
> +
> + ret = devm_request_irq(dev, irq, rzn1_wdt_irq, 0,
> + np->name, wdt);
> + if (ret) {
> + dev_err(dev, "failed to request irq %d\n", irq);
> + return ret;
> + }
> +
> + clk = devm_clk_get(dev, NULL);
> + if (IS_ERR(clk)) {
> + dev_err(dev, "failed to get the clock\n");
> + return PTR_ERR(clk);
> + }
> +
> + ret = clk_prepare_enable(clk);
> + if (ret) {
> + dev_err(dev, "failed to prepare/enable the clock\n");
> + return ret;
> + }
> +
> + ret = devm_add_action_or_reset(dev, rzn1_wdt_clk_disable_unprepare,
> + clk);
> + if (ret) {
> + dev_err(dev, "failed to register clock unprepare callback\n");
> + clk_disable_unprepare(clk);
Please drop this, as devm_add_action_or_reset() calls the
action on failure.
> + return ret;
> + }
> +
> + wdt->clk_rate = clk_get_rate(clk);
> + if (!wdt->clk_rate) {
> + dev_err(dev, "failed to get the clock rate\n");
> + return -EINVAL;
> + }
> +
> + /*
> + * The period of the watchdog cannot be changed once set
> + * and is limited to a very short period.
> + * Configure it for a 1s period once and for all, and
> + * rely on the heart-beat provided by the watchdog core
> + * to make this usable by the user-space.
> + */
> + wdt->wdt.max_hw_heartbeat_ms = get_max_heart_beat(wdt->clk_rate);
> + if (wdt->wdt.max_hw_heartbeat_ms > 1000)
> + wdt->wdt.max_hw_heartbeat_ms = 1000;
> +
> + wdt->wdt.timeout = DEFAULT_TIMEOUT;
> + ret = watchdog_init_timeout(&wdt->wdt, 0, dev);
> +
> + return devm_watchdog_register_device(dev, &wdt->wdt);
> +}
> +
> +
> +static const struct of_device_id rzn1_wdt_match[] = {
> + { .compatible = "renesas,r9a06g032-wdt" },
No need to match on the soc-specific compatible value, as the
family-specific value should be present in the DTB, too.
> + { .compatible = "renesas,rzn1-wdt" },
> + {},
> +};
> +MODULE_DEVICE_TABLE(of, rzn1_wdt_match);
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
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