Messages in this thread | | | From | Geert Uytterhoeven <> | Date | Mon, 7 Feb 2022 17:35:59 +0100 | Subject | Re: [PATCH 6/6] watchdog: Add Renesas RZ/N1 Watchdog driver |
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Hi Jean-Jacques,
On Fri, Feb 4, 2022 at 5:18 PM Jean-Jacques Hiblot <jjhiblot@traphandler.com> wrote: > From: Phil Edworthy <phil.edworthy@renesas.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@renesas.com> > Signed-off-by: Jean-Jacques Hiblot <jjhiblot@traphandler.com>
Thanks for your patch!
> --- /dev/null > +++ b/drivers/watchdog/rzn1_wdt.c > @@ -0,0 +1,197 @@ > +// 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 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 BIT(14)
"BIT(14)" is a bit strange, as this is used as a scalar, never as a bitmask.
> +static int rzn1_wdt_set_timeout(struct watchdog_device *w, unsigned int t) > +{ > + struct rzn1_watchdog *wdt = to_rzn1_watchdog(w); > + > + w->timeout = t; > + > + wdt->reload_val = (t * wdt->clk_rate) / RZN1_WDT_PRESCALER;
I guess the multiplication can overflow in 32-bit arithmetic?
> + > + return 0; > +}
> +static int rzn1_wdt_probe(struct platform_device *pdev) > +{ > + struct rzn1_watchdog *wdt; > + int ret; > + struct device_node *np = pdev->dev.of_node; > + int err; > + struct clk *clk; > + > + wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL); > + if (!wdt) > + return -ENOMEM; > + wdt->dev = &pdev->dev; > + wdt->wdt = rzn1_wdt_dev; > + platform_set_drvdata(pdev, wdt); > + > + wdt->base = devm_platform_ioremap_resource(pdev, 0); > + if (IS_ERR(wdt->base)) { > + dev_err(wdt->dev, "unable to get register bank\n");
No need to print an error message, __devm_ioremap_resource() takes care of that.
> + return PTR_ERR(wdt->base); > + } > + wdt->irq = irq_of_parse_and_map(np, 0); > + if (wdt->irq == NO_IRQ) { > + dev_err(wdt->dev, "failed to get IRQ from DT\n"); > + return -EINVAL; > + }
Please use platform_get_irq() instead. Note that on error, it prints an error message, and returns a negative value. So you cannot assign it to wdt->irq before checking, as the latter is unsigned:
ret = platform_get_irq(pdev, 0); if (ret < 0) return ret;
wdt->irq = ret;
> + wdt->reload_val = RZN1_WDT_MAX; > + wdt->wdt.max_hw_heartbeat_ms = (RZN1_WDT_MAX * 1000) / > + (wdt->clk_rate / RZN1_WDT_PRESCALER);
To avoid loss of precision, it's better to reorder operations. As the dividend doesn't fit in 32-bit, you have to use a 64-bit-by-unsigned-long division:
div64_ul(RZN1_WDT_MAX * 1000ULL * RZN1_WDT_PRESCALER, wdt->clk_rate);
> + > + ret = watchdog_init_timeout(&wdt->wdt, 0, &pdev->dev); > + if (ret) > + dev_warn(&pdev->dev, "Specified timeout invalid, using default"); > + > + ret = devm_watchdog_register_device(&pdev->dev, &wdt->wdt);
"return devm_watchdog_register_device(...);"?
> + if (ret) > + goto error; > + > + dev_info(wdt->dev, "Initialized\n"); > + > + return 0;
Gr{oetje,eeting}s,
Geert
-- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-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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