Re: [PATCH v4 2/6] watchdog: npcm: Enable clock if provided

Guenter Roeck
2022-09-25T17:01:00Z

On Fri, Jun 10, 2022 at 09:21:37AM +0200, Jonathan Neuschäfer wrote:
> On the Nuvoton WPCM450 SoC, with its upcoming clock driver, peripheral
> clocks are individually gated and ungated. Therefore, the watchdog
> driver must be able to ungate the watchdog clock.
>
> Signed-off-by: Jonathan Neuschäfer <j.neuschaefer@gmx.net>

Reviewed-by: Guenter Roeck <linux@roeck-us.net>

> ---
>
> v4:
> - Don't disable clock in npcm_wdt_restart function
>
> v3:
> - https://lore.kernel.org/lkml/20220508194333.2170161-4-j.neuschaefer@gmx.net/
> - Add enable/disable calls to npcm_wdt_restart handler
> - Not applied due to the above change: Acked-by: Guenter Roeck <linux@roeck-us.net>
>
> v2:
> - https://lore.kernel.org/lkml/20220429172030.398011-4-j.neuschaefer@gmx.net/
> - Add clk_disable_unprepare call, suggested by Guenter Roeck
>
> v1:
> - https://lore.kernel.org/lkml/20220422183012.444674-4-j.neuschaefer@gmx.net/
> ---
> drivers/watchdog/npcm_wdt.c | 16 ++++++++++++++++
> 1 file changed, 16 insertions(+)
>
> --
> 2.35.1
>
> diff --git a/drivers/watchdog/npcm_wdt.c b/drivers/watchdog/npcm_wdt.c
> index 28a24caa2627c..a5dd1c2301374 100644
> --- a/drivers/watchdog/npcm_wdt.c
> +++ b/drivers/watchdog/npcm_wdt.c
> @@ -3,6 +3,7 @@
> // Copyright (c) 2018 IBM Corp.
>
> #include <linux/bitops.h>
> +#include <linux/clk.h>
> #include <linux/delay.h>
> #include <linux/interrupt.h>
> #include <linux/kernel.h>
> @@ -43,6 +44,7 @@
> struct npcm_wdt {
> struct watchdog_device wdd;
> void __iomem *reg;
> + struct clk *clk;
> };
>
> static inline struct npcm_wdt *to_npcm_wdt(struct watchdog_device *wdd)
> @@ -66,6 +68,9 @@ static int npcm_wdt_start(struct watchdog_device *wdd)
> struct npcm_wdt *wdt = to_npcm_wdt(wdd);
> u32 val;
>
> + if (wdt->clk)
> + clk_prepare_enable(wdt->clk);
> +
> if (wdd->timeout < 2)
> val = 0x800;
> else if (wdd->timeout < 3)
> @@ -100,6 +105,9 @@ static int npcm_wdt_stop(struct watchdog_device *wdd)
>
> writel(0, wdt->reg);
>
> + if (wdt->clk)
> + clk_disable_unprepare(wdt->clk);
> +
> return 0;
> }
>
> @@ -147,6 +155,10 @@ static int npcm_wdt_restart(struct watchdog_device *wdd,
> {
> struct npcm_wdt *wdt = to_npcm_wdt(wdd);
>
> + /* For reset, we start the WDT clock and leave it running. */
> + if (wdt->clk)
> + clk_prepare_enable(wdt->clk);
> +
> writel(NPCM_WTR | NPCM_WTRE | NPCM_WTE, wdt->reg);
> udelay(1000);
>
> @@ -191,6 +203,10 @@ static int npcm_wdt_probe(struct platform_device *pdev)
> if (IS_ERR(wdt->reg))
> return PTR_ERR(wdt->reg);
>
> + wdt->clk = devm_clk_get_optional(&pdev->dev, NULL);
> + if (IS_ERR(wdt->clk))
> + return PTR_ERR(wdt->clk);
> +
> irq = platform_get_irq(pdev, 0);
> if (irq < 0)
> return irq;