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SubjectRe: [RFC PATCH v2] watchdog: sp805: Add clock-frequency property
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On 07/09/2018 03:19 AM, Srinath Mannam wrote:
> When using ACPI node, binding clock devices are
> not available as device tree, So clock-frequency
> property given in _DSD object of ACPI device is
> used to calculate Watchdog rate.
>
> Signed-off-by: Srinath Mannam <srinath.mannam@broadcom.com>
> ---
> drivers/watchdog/sp805_wdt.c | 34 ++++++++++++++++++++++++++--------
> 1 file changed, 26 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/watchdog/sp805_wdt.c b/drivers/watchdog/sp805_wdt.c
> index 9849db0..ad5ed64 100644
> --- a/drivers/watchdog/sp805_wdt.c
> +++ b/drivers/watchdog/sp805_wdt.c
> @@ -11,6 +11,7 @@
> * warranty of any kind, whether express or implied.
> */
>
> +#include <linux/acpi.h>
> #include <linux/device.h>
> #include <linux/resource.h>
> #include <linux/amba/bus.h>
> @@ -22,6 +23,7 @@
> #include <linux/math64.h>
> #include <linux/module.h>
> #include <linux/moduleparam.h>
> +#include <linux/of.h>
> #include <linux/pm.h>
> #include <linux/slab.h>
> #include <linux/spinlock.h>
> @@ -65,6 +67,7 @@ struct sp805_wdt {
> spinlock_t lock;
> void __iomem *base;
> struct clk *clk;
> + u64 rate;
> struct amba_device *adev;
> unsigned int load_val;
> };
> @@ -80,7 +83,7 @@ static int wdt_setload(struct watchdog_device *wdd, unsigned int timeout)
> struct sp805_wdt *wdt = watchdog_get_drvdata(wdd);
> u64 load, rate;
>
> - rate = clk_get_rate(wdt->clk);
> + rate = wdt->rate;
>
> /*
> * sp805 runs counter with given value twice, after the end of first
> @@ -106,9 +109,7 @@ static int wdt_setload(struct watchdog_device *wdd, unsigned int timeout)
> static unsigned int wdt_timeleft(struct watchdog_device *wdd)
> {
> struct sp805_wdt *wdt = watchdog_get_drvdata(wdd);
> - u64 load, rate;
> -
> - rate = clk_get_rate(wdt->clk);
> + u64 load;
>
> spin_lock(&wdt->lock);
> load = readl_relaxed(wdt->base + WDTVALUE);
> @@ -118,7 +119,7 @@ static unsigned int wdt_timeleft(struct watchdog_device *wdd)
> load += wdt->load_val + 1;
> spin_unlock(&wdt->lock);
>
> - return div_u64(load, rate);
> + return div_u64(load, wdt->rate);
> }
>
> static int
> @@ -228,10 +229,27 @@ sp805_wdt_probe(struct amba_device *adev, const struct amba_id *id)
> if (IS_ERR(wdt->base))
> return PTR_ERR(wdt->base);
>
> - wdt->clk = devm_clk_get(&adev->dev, NULL);
> - if (IS_ERR(wdt->clk)) {
> + if (adev->dev.of_node) {
> + wdt->clk = devm_clk_get(&adev->dev, NULL);
> + if (IS_ERR(wdt->clk)) {
> + ret = PTR_ERR(wdt->clk);
> + wdt->clk = NULL;

Clearing wdt->clk is useless.

> + } else
> + wdt->rate = clk_get_rate(wdt->clk);

The else branch should be in { } as well per coding style.

> + } else if (has_acpi_companion(&adev->dev)) {
> + /*
> + * When Driver probe with ACPI device, clock devices
> + * are not available, so watchdog rate get from
> + * clock-frequency property given in _DSD object.
> + */
> + device_property_read_u64(&adev->dev, "clock-frequency",
> + &wdt->rate);

Continuation line alignment is off.

Still not documented. Maybe that is common for ACPI devices nowadays.
If so, I'll need at least a pointer to a document or something declaring
that ACPI devices do not use well documented properties, and a confirmation
that using such properties is acceptable in the Linux kernel.

> + if (!wdt->rate)
> + ret = -ENODEV;
> + }
> +
> + if (ret) {
> dev_warn(&adev->dev, "Clock not found\n");
> - ret = PTR_ERR(wdt->clk);
> goto err;
> }

Please move the error handling to where the error occurs. While doing that,
please change the message to dev_err() - this is an error, not a warning -
and change the second error message to match the error (it did not find
the property).

Also, return directly - the goto just generates another error message
which is ridiculous.

Thanks,
Guenter

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