lkml.org 
[lkml]   [2020]   [Mar]   [15]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 5/7] watchdog: dw_wdt: Support devices with asynch clocks
On Fri, Mar 06, 2020 at 04:27:45PM +0300, Sergey.Semin@baikalelectronics.ru wrote:
> From: Serge Semin <Sergey.Semin@baikalelectronics.ru>
>
> 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>
> Signed-off-by: Alexey Malahov <Alexey.Malahov@baikalelectronics.ru>
> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
> Cc: Paul Burton <paulburton@kernel.org>
> Cc: Ralf Baechle <ralf@linux-mips.org>
> ---
> 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 4a57b7d777dc..eb909c63a1b5 100644
> --- a/drivers/watchdog/dw_wdt.c
> +++ b/drivers/watchdog/dw_wdt.c
> @@ -61,6 +61,7 @@ MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
> struct dw_wdt {
> void __iomem *regs;
> struct clk *clk;
> + struct clk *pclk;
> unsigned long rate;
> unsigned int max_top;
> unsigned int timeouts[DW_WDT_NUM_TOPS];
> @@ -270,6 +271,7 @@ 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;
> @@ -283,6 +285,12 @@ 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);
>
> @@ -344,9 +352,18 @@ 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 clocks 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)
> @@ -358,10 +375,27 @@ static int dw_wdt_drv_probe(struct platform_device *pdev)
> goto out_disable_clk;
> }
>
> + /*
> + * Request APB clocks 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 reference is left optional. If it it's failed to 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);

Not every implementation of clk_enable() checks for a NULL parameter.
Some return an error. This can not be trusted to work on all platforms /
architectures.

> + 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);
> @@ -399,10 +433,13 @@ 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;
> @@ -414,6 +451,7 @@ 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;

\
 
 \ /
  Last update: 2020-03-15 15:23    [W:0.071 / U:6.176 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site