linux-kernel - Re: [PATCH v5] mfd: syscon: Add hardware spinlock support

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Date:   Thu, 30 Nov 2017 18:45:35 +0800
From:   Baolin Wang <baolin.wang@...aro.org>
To:     Vladimir Zapolskiy <vladimir_zapolskiy@...tor.com>
Cc:     Lee Jones <lee.jones@...aro.org>, Arnd Bergmann <arnd@...db.de>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Mark Brown <broonie@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        DTML <devicetree@...r.kernel.org>
Subject: Re: [PATCH v5] mfd: syscon: Add hardware spinlock support

On 30 November 2017 at 18:38, Vladimir Zapolskiy
<vladimir_zapolskiy@...tor.com> wrote:
> On 11/30/2017 11:10 AM, Baolin Wang wrote:
>> Some system control registers need hardware spinlock to synchronize
>> between the multiple subsystems, so we should add hardware spinlock
>> support for syscon.
>>
>> Signed-off-by: Baolin Wang <baolin.wang@...aro.org>
>> Acked-by: Rob Herring <robh@...nel.org>
>> ---
>> Changes since v4:
>>  - Add one exapmle to show how to add hwlock.
>>  - Fix the coding style issue.
>>
>> Changes since v3:
>>  - Add error handling for of_hwspin_lock_get_id()
>>
>> Changes since v2:
>>  - Add acked tag from Rob.
>>
>> Changes since v1:
>>  - Remove timeout configuration.
>>  - Modify the binding file to add hwlocks.
>> ---
>>  Documentation/devicetree/bindings/mfd/syscon.txt |    8 ++++++++
>>  drivers/mfd/syscon.c                             |   21 +++++++++++++++++++++
>>  2 files changed, 29 insertions(+)
>>
>> diff --git a/Documentation/devicetree/bindings/mfd/syscon.txt b/Documentation/devicetree/bindings/mfd/syscon.txt
>> index 8b92d45..25d9e9c 100644
>> --- a/Documentation/devicetree/bindings/mfd/syscon.txt
>> +++ b/Documentation/devicetree/bindings/mfd/syscon.txt
>> @@ -16,9 +16,17 @@ Required properties:
>>  Optional property:
>>  - reg-io-width: the size (in bytes) of the IO accesses that should be
>>    performed on the device.
>> +- hwlocks: reference to a phandle of a hardware spinlock provider node.
>>
>>  Examples:
>>  gpr: iomuxc-gpr@...0000 {
>>       compatible = "fsl,imx6q-iomuxc-gpr", "syscon";
>>       reg = <0x020e0000 0x38>;
>> +     hwlocks = <&hwlock1 1>;
>> +};
>> +
>> +hwlock1: hwspinlock@...00000 {
>> +     ...
>> +     reg = <0x40500000 0x1000>;
>> +     #hwlock-cells = <1>;
>>  };
>> diff --git a/drivers/mfd/syscon.c b/drivers/mfd/syscon.c
>> index b93fe4c..5b67dbc 100644
>> --- a/drivers/mfd/syscon.c
>> +++ b/drivers/mfd/syscon.c
>> @@ -13,6 +13,7 @@
>>   */
>>
>>  #include <linux/err.h>
>> +#include <linux/hwspinlock.h>
>>  #include <linux/io.h>
>>  #include <linux/module.h>
>>  #include <linux/list.h>
>> @@ -87,6 +88,26 @@ static struct syscon *of_syscon_register(struct device_node *np)
>>       if (ret)
>>               reg_io_width = 4;
>>
>> +     ret = of_hwspin_lock_get_id(np, 0);
>> +     if (ret > 0) {
>> +             syscon_config.hwlock_id = ret;
>> +             syscon_config.hwlock_mode = HWLOCK_IRQSTATE;
>> +     } else {
>> +             switch (ret) {
>> +             case -ENOENT:
>> +                     /* Ignore missing hwlock, it's optional. */
>> +                     break;
>> +             case 0:
>> +                     ret = -EINVAL;
>> +                     /* fall-through */
>
> It breaks the execution on all kernels without CONFIG_HWSPINLOCK enabled.

Ah, your are correct. Sorry, I missed this case. I will fix this in
next version. Thanks.

-- 
Baolin.wang
Best Regards