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Message-ID: <20220514141443.GA1319155@roeck-us.net>
Date: Sat, 14 May 2022 07:14:43 -0700
From: Guenter Roeck <linux@...ck-us.net>
To: Jean-Jacques Hiblot <jjhiblot@...phandler.com>
Cc: wim@...ux-watchdog.org, geert+renesas@...der.be,
tzungbi@...nel.org, linux-watchdog@...r.kernel.org,
linux-renesas-soc@...r.kernel.org, linux-kernel@...r.kernel.org,
Phil Edworthy <phil.edworthy@...esas.com>
Subject: Re: [PATCH v7 2/2] watchdog: Add Renesas RZ/N1 Watchdog driver
On Wed, Apr 27, 2022 at 03:55:31PM +0200, Jean-Jacques Hiblot 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>
> Reviewed-by: Tzung-Bi Shih <tzungbi@...nel.org>
Reviewed-by: Guenter Roeck <linux@...ck-us.net>
> ---
> drivers/watchdog/Kconfig | 8 ++
> drivers/watchdog/Makefile | 1 +
> drivers/watchdog/rzn1_wdt.c | 203 ++++++++++++++++++++++++++++++++++++
> 3 files changed, 212 insertions(+)
> create mode 100644 drivers/watchdog/rzn1_wdt.c
>
> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
> index c4e82a8d863f..4d5e503c8950 100644
> --- a/drivers/watchdog/Kconfig
> +++ b/drivers/watchdog/Kconfig
> @@ -883,6 +883,14 @@ 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_RZN1WDT
> + tristate "Renesas RZ/N1 watchdog"
> + depends on ARCH_RENESAS || COMPILE_TEST
> + select WATCHDOG_CORE
> + help
> + This driver adds watchdog support for the integrated watchdogs in the
> + Renesas RZ/N1 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
> diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
> index f7da867e8782..38d38564f47b 100644
> --- a/drivers/watchdog/Makefile
> +++ b/drivers/watchdog/Makefile
> @@ -84,6 +84,7 @@ 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-$(CONFIG_RENESAS_RZN1WDT) += rzn1_wdt.o
> obj-$(CONFIG_RENESAS_RZG2LWDT) += rzg2l_wdt.o
> obj-$(CONFIG_ASPEED_WATCHDOG) += aspeed_wdt.o
> obj-$(CONFIG_STM32_WATCHDOG) += stm32_iwdg.o
> diff --git a/drivers/watchdog/rzn1_wdt.c b/drivers/watchdog/rzn1_wdt.c
> new file mode 100644
> index 000000000000..55ab384b9965
> --- /dev/null
> +++ b/drivers/watchdog/rzn1_wdt.c
> @@ -0,0 +1,203 @@
> +// 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/reboot.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 wdtdev;
> + void __iomem *base;
> + unsigned long clk_rate_khz;
> +};
> +
> +static inline uint32_t max_heart_beat_ms(unsigned long clk_rate_khz)
> +{
> + return (RZN1_WDT_MAX * RZN1_WDT_PRESCALER) / clk_rate_khz;
> +}
> +
> +static inline uint32_t compute_reload_value(uint32_t tick_ms,
> + unsigned long clk_rate_khz)
> +{
> + return (tick_ms * clk_rate_khz) / RZN1_WDT_PRESCALER;
> +}
> +
> +static int rzn1_wdt_ping(struct watchdog_device *w)
> +{
> + struct rzn1_watchdog *wdt = watchdog_get_drvdata(w);
> +
> + /* Any value retrigggers the watchdog */
> + writel(0, wdt->base + RZN1_WDT_RETRIGGER);
> +
> + return 0;
> +}
> +
> +static int rzn1_wdt_start(struct watchdog_device *w)
> +{
> + struct rzn1_watchdog *wdt = watchdog_get_drvdata(w);
> + u32 val;
> +
> + /*
> + * The hardware allows you to write to this reg only once.
> + * Since this includes the reload value, there is no way to change the
> + * timeout once started. Also note that the WDT clock is half the bus
> + * fabric clock rate, so if the bus fabric clock rate is changed after
> + * the WDT is started, the WDT interval will be wrong.
> + */
> + val = RZN1_WDT_RETRIGGER_WDSI;
> + val |= RZN1_WDT_RETRIGGER_ENABLE;
> + val |= RZN1_WDT_RETRIGGER_PRESCALE;
> + val |= compute_reload_value(w->max_hw_heartbeat_ms, wdt->clk_rate_khz);
> + writel(val, wdt->base + RZN1_WDT_RETRIGGER);
> +
> + return 0;
> +}
> +
> +static irqreturn_t rzn1_wdt_irq(int irq, void *_wdt)
> +{
> + pr_crit("RZN1 Watchdog. Initiating system reboot\n");
> + emergency_restart();
> +
> + return IRQ_HANDLED;
> +}
> +
> +static struct watchdog_info rzn1_wdt_info = {
> + .identity = "RZ/N1 Watchdog",
> + .options = WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
> +};
> +
> +static const struct watchdog_ops rzn1_wdt_ops = {
> + .owner = THIS_MODULE,
> + .start = rzn1_wdt_start,
> + .ping = rzn1_wdt_ping,
> +};
> +
> +static void rzn1_wdt_clk_disable_unprepare(void *data)
> +{
> + clk_disable_unprepare(data);
> +}
> +
> +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;
> + unsigned long clk_rate;
> + int ret;
> + int irq;
> +
> + wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
> + if (!wdt)
> + return -ENOMEM;
> +
> + 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)
> + 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)
> + return ret;
> +
> + clk_rate = clk_get_rate(clk);
> + if (!clk_rate) {
> + dev_err(dev, "failed to get the clock rate\n");
> + return -EINVAL;
> + }
> +
> + wdt->clk_rate_khz = clk_rate / 1000;
> + wdt->wdtdev.info = &rzn1_wdt_info,
> + wdt->wdtdev.ops = &rzn1_wdt_ops,
> + wdt->wdtdev.status = WATCHDOG_NOWAYOUT_INIT_STATUS,
> + wdt->wdtdev.parent = dev;
> + /*
> + * 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->wdtdev.max_hw_heartbeat_ms = max_heart_beat_ms(wdt->clk_rate_khz);
> + if (wdt->wdtdev.max_hw_heartbeat_ms > 1000)
> + wdt->wdtdev.max_hw_heartbeat_ms = 1000;
> +
> + wdt->wdtdev.timeout = DEFAULT_TIMEOUT;
> + ret = watchdog_init_timeout(&wdt->wdtdev, 0, dev);
> + if (ret)
> + return ret;
> +
> + watchdog_set_drvdata(&wdt->wdtdev, wdt);
> +
> + return devm_watchdog_register_device(dev, &wdt->wdtdev);
> +}
> +
> +
> +static const struct of_device_id rzn1_wdt_match[] = {
> + { .compatible = "renesas,rzn1-wdt" },
> + {},
> +};
> +MODULE_DEVICE_TABLE(of, rzn1_wdt_match);
> +
> +static struct platform_driver rzn1_wdt_driver = {
> + .probe = rzn1_wdt_probe,
> + .driver = {
> + .name = KBUILD_MODNAME,
> + .of_match_table = rzn1_wdt_match,
> + },
> +};
> +
> +module_platform_driver(rzn1_wdt_driver);
> +
> +MODULE_DESCRIPTION("Renesas RZ/N1 hardware watchdog");
> +MODULE_AUTHOR("Phil Edworthy <phil.edworthy@...esas.com>");
> +MODULE_LICENSE("GPL");
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