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SubjectRe: [RFC PATCH v3] watchdog: sp805: Add clock-frequency property
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On 07/11/2018 06:22 AM, Srinath Mannam wrote:
> Hi Guenter,
>
> Thank you very much for all the help with your feedback and review
> comments to complete the changes very fast.
>
> About the documentation..
> I have gone through few similar patches available in the kernel are
> listed in the mail of previous version.
> No documentation available in Linux for the properties used in those
> patches also.

" No documentation available _in Linux_"

Emphasis mine. Yes, I noticed this as well. I was asking for a reference
to documentation _outside_ Linux. Sorry for not being more specific.

Guenter

> For example,
> 1: "src-clock-hz" property added in the part of ACPI support with the
> below patch.
> Patch details: commit 515da746983bc6382e380ba8b1ce9345a9550ffe
> Author: Naveen Kaje <nkaje@codeaurora.org>
> Date: Tue Oct 11 10:27:56 2016 -0600
>
> i2c: qup: add ACPI support
> 2: "amd,dma-freq" property added in the part of ACPI support with the
> below patch
> commit 82a19035d000c8b4fd7d6f61b614f63dec75d389
> Author: Lendacky, Thomas <Thomas.Lendacky@amd.com>
> Date: Fri Jan 16 12:47:16 2015 -0600
>
> amd-xgbe: Add ACPI support
>
> Regards,
> Srinath.
>
>
>
>
> On Wed, Jul 11, 2018 at 3:05 AM, Guenter Roeck <linux@roeck-us.net> wrote:
>> On Tue, Jul 10, 2018 at 02:14:39PM +0530, 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>
>>
>> I am ok with the patch itself. All that is missing now is a
>> reference to the _DSD property documentation. Is that published
>> somewhere or is it all wild-wild-west ?
>>
>> Thanks,
>> Guenter
>>
>>> ---
>>> drivers/watchdog/sp805_wdt.c | 35 +++++++++++++++++++++++++----------
>>> 1 file changed, 25 insertions(+), 10 deletions(-)
>>>
>>> diff --git a/drivers/watchdog/sp805_wdt.c b/drivers/watchdog/sp805_wdt.c
>>> index 9849db0..a896b1c 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
>>> @@ -228,11 +229,25 @@ 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)) {
>>> - dev_warn(&adev->dev, "Clock not found\n");
>>> - ret = PTR_ERR(wdt->clk);
>>> - goto err;
>>> + if (adev->dev.of_node) {
>>> + wdt->clk = devm_clk_get(&adev->dev, NULL);
>>> + if (IS_ERR(wdt->clk)) {
>>> + dev_err(&adev->dev, "Clock not found\n");
>>> + return PTR_ERR(wdt->clk);
>>> + }
>>> + wdt->rate = clk_get_rate(wdt->clk);
>>> + } 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);
>>> + if (!wdt->rate) {
>>> + dev_err(&adev->dev, "no clock-frequency property\n");
>>> + return -ENODEV;
>>> + }
>>> }
>>>
>>> wdt->adev = adev;
>>> --
>>> 2.7.4
>>>
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