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SubjectRe: [PATCH v3 5/7] watchdog: dw_wdt: Support devices with asynch clocks
On Tue, May 26, 2020 at 06:41:21PM +0300, Serge Semin wrote:
> DW Watchdog IP core can be synthesised with asynchronous timer/APB
> clocks support (WDT_ASYNC_CLK_MODE_ENABLE == 1). In this case
> separate clock signals are supposed to be used to feed watchdog timer
> and APB interface of the device. Currently the driver supports
> the synchronous mode only. Since there is no way to determine which
> mode was actually activated for device from its registers, we have to
> rely on the platform device configuration data. If optional "pclk"
> clock source is supplied, we consider the device working in asynchronous
> mode, otherwise the driver falls back to the synchronous configuration.
>
> Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
> Cc: Alexey Malahov <Alexey.Malahov@baikalelectronics.ru>
> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
> Cc: Arnd Bergmann <arnd@arndb.de>
> Cc: Rob Herring <robh+dt@kernel.org>
> Cc: linux-mips@vger.kernel.org
> Cc: devicetree@vger.kernel.org

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

> ---
>
> Changelog v2:
> - Rearrange SoBs.
> ---
> drivers/watchdog/dw_wdt.c | 48 +++++++++++++++++++++++++++++++++++----
> 1 file changed, 43 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/watchdog/dw_wdt.c b/drivers/watchdog/dw_wdt.c
> index 693c0d1fd796..efbc36872670 100644
> --- a/drivers/watchdog/dw_wdt.c
> +++ b/drivers/watchdog/dw_wdt.c
> @@ -68,6 +68,7 @@ struct dw_wdt_timeout {
> struct dw_wdt {
> void __iomem *regs;
> struct clk *clk;
> + struct clk *pclk;
> unsigned long rate;
> struct dw_wdt_timeout timeouts[DW_WDT_NUM_TOPS];
> struct watchdog_device wdd;
> @@ -274,6 +275,7 @@ static int dw_wdt_suspend(struct device *dev)
> dw_wdt->control = readl(dw_wdt->regs + WDOG_CONTROL_REG_OFFSET);
> dw_wdt->timeout = readl(dw_wdt->regs + WDOG_TIMEOUT_RANGE_REG_OFFSET);
>
> + clk_disable_unprepare(dw_wdt->pclk);
> clk_disable_unprepare(dw_wdt->clk);
>
> return 0;
> @@ -287,6 +289,12 @@ static int dw_wdt_resume(struct device *dev)
> if (err)
> return err;
>
> + err = clk_prepare_enable(dw_wdt->pclk);
> + if (err) {
> + clk_disable_unprepare(dw_wdt->clk);
> + return err;
> + }
> +
> writel(dw_wdt->timeout, dw_wdt->regs + WDOG_TIMEOUT_RANGE_REG_OFFSET);
> writel(dw_wdt->control, dw_wdt->regs + WDOG_CONTROL_REG_OFFSET);
>
> @@ -393,9 +401,18 @@ static int dw_wdt_drv_probe(struct platform_device *pdev)
> if (IS_ERR(dw_wdt->regs))
> return PTR_ERR(dw_wdt->regs);
>
> - dw_wdt->clk = devm_clk_get(dev, NULL);
> - if (IS_ERR(dw_wdt->clk))
> - return PTR_ERR(dw_wdt->clk);
> + /*
> + * Try to request the watchdog dedicated timer clock source. It must
> + * be supplied if asynchronous mode is enabled. Otherwise fallback
> + * to the common timer/bus clocks configuration, in which the very
> + * first found clock supply both timer and APB signals.
> + */
> + dw_wdt->clk = devm_clk_get(dev, "tclk");
> + if (IS_ERR(dw_wdt->clk)) {
> + dw_wdt->clk = devm_clk_get(dev, NULL);
> + if (IS_ERR(dw_wdt->clk))
> + return PTR_ERR(dw_wdt->clk);
> + }
>
> ret = clk_prepare_enable(dw_wdt->clk);
> if (ret)
> @@ -407,10 +424,27 @@ static int dw_wdt_drv_probe(struct platform_device *pdev)
> goto out_disable_clk;
> }
>
> + /*
> + * Request APB clock if device is configured with async clocks mode.
> + * In this case both tclk and pclk clocks are supposed to be specified.
> + * Alas we can't know for sure whether async mode was really activated,
> + * so the pclk phandle reference is left optional. If it couldn't be
> + * found we consider the device configured in synchronous clocks mode.
> + */
> + dw_wdt->pclk = devm_clk_get_optional(dev, "pclk");
> + if (IS_ERR(dw_wdt->pclk)) {
> + ret = PTR_ERR(dw_wdt->pclk);
> + goto out_disable_clk;
> + }
> +
> + ret = clk_prepare_enable(dw_wdt->pclk);
> + if (ret)
> + goto out_disable_clk;
> +
> dw_wdt->rst = devm_reset_control_get_optional_shared(&pdev->dev, NULL);
> if (IS_ERR(dw_wdt->rst)) {
> ret = PTR_ERR(dw_wdt->rst);
> - goto out_disable_clk;
> + goto out_disable_pclk;
> }
>
> reset_control_deassert(dw_wdt->rst);
> @@ -449,10 +483,13 @@ static int dw_wdt_drv_probe(struct platform_device *pdev)
>
> ret = watchdog_register_device(wdd);
> if (ret)
> - goto out_disable_clk;
> + goto out_disable_pclk;
>
> return 0;
>
> +out_disable_pclk:
> + clk_disable_unprepare(dw_wdt->pclk);
> +
> out_disable_clk:
> clk_disable_unprepare(dw_wdt->clk);
> return ret;
> @@ -464,6 +501,7 @@ static int dw_wdt_drv_remove(struct platform_device *pdev)
>
> watchdog_unregister_device(&dw_wdt->wdd);
> reset_control_assert(dw_wdt->rst);
> + clk_disable_unprepare(dw_wdt->pclk);
> clk_disable_unprepare(dw_wdt->clk);
>
> return 0;

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