Re: [PATCH edk2-platforms 3/8] Silicon/NXP/Pcf8563RealTimeClockLib: avoid driver binding protocol

[Ard Biesheuvel <ard.biesheuvel@linaro.org>]

On 25 January 2018 at 12:54, Leif Lindholm <leif.lindholm@linaro.org> wrote:
> On Thu, Jan 25, 2018 at 12:27:31PM +0000, Ard Biesheuvel wrote:
>> Instead of registering a notification callback on the driver binding
>> protocol, and attempting to connect our I2C master handle each time
>> a new driver is registered, switch to the more obvious approach of
>> registering a notification callback on the I2C master protocol directly.
>>
>> The original code was written under the assumption that it would make
>> the RTC available at an earlier time, but given that all handles that
>> are created during the execution of a driver entry point are connected
>> by DXE core right away (i.e., before StartImage() returns), this is not
>> really necessary, and in fact, may result in the driver already having
>> been connected by the time we attempt to connect it.
>>
>> Note that it is now up to the platform to ensure that ConnectController()
>> is called for the handle if DXE core does not call it by itself, or does
>> call it but at a time when no I2C master protocol driver is available
>> yet.
>
> Presumably the platforms in edk2-platforms using this library already
> follow these constraints?
>

There aren't any. But I did CC the NXP guys on this patch when I sent
it the first time around, to give them the head's up that they
probably shouldn't copy the original pattern.

> If so:
> Reviewed-by: Leif Lindholm <leif.lindholm@linaro.org>
>

Thanks.

>> Contributed-under: TianoCore Contribution Agreement 1.1
>> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
>> ---
>>  Silicon/NXP/Library/Pcf8563RealTimeClockLib/Pcf8563RealTimeClockLib.c   | 31 ++++++++------------
>>  Silicon/NXP/Library/Pcf8563RealTimeClockLib/Pcf8563RealTimeClockLib.inf |  1 -
>>  2 files changed, 13 insertions(+), 19 deletions(-)
>>
>> diff --git a/Silicon/NXP/Library/Pcf8563RealTimeClockLib/Pcf8563RealTimeClockLib.c b/Silicon/NXP/Library/Pcf8563RealTimeClockLib/Pcf8563RealTimeClockLib.c
>> index 6bc4aef28849..fb58e1feb424 100644
>> --- a/Silicon/NXP/Library/Pcf8563RealTimeClockLib/Pcf8563RealTimeClockLib.c
>> +++ b/Silicon/NXP/Library/Pcf8563RealTimeClockLib/Pcf8563RealTimeClockLib.c
>> @@ -41,7 +41,7 @@
>>  #define EPOCH_BASE                2000
>>
>>  STATIC EFI_HANDLE                 mI2cMasterHandle;
>> -STATIC VOID                       *mDriverEventRegistration;
>> +STATIC VOID                       *mI2cMasterEventRegistration;
>>  STATIC EFI_I2C_MASTER_PROTOCOL    *mI2cMaster;
>>  STATIC EFI_EVENT                  mRtcVirtualAddrChangeEvent;
>>
>> @@ -263,12 +263,12 @@ LibSetWakeupTime (
>>
>>  STATIC
>>  VOID
>> -DriverRegistrationEvent (
>> +I2cMasterRegistrationEvent (
>>    IN  EFI_EVENT       Event,
>>    IN  VOID            *Context
>>    )
>>  {
>> -  EFI_HANDLE                Handle[2];
>> +  EFI_HANDLE                Handle;
>>    UINTN                     BufferSize;
>>    EFI_STATUS                Status;
>>    EFI_I2C_MASTER_PROTOCOL   *I2cMaster;
>> @@ -280,10 +280,10 @@ DriverRegistrationEvent (
>>    do {
>>      BufferSize = sizeof (EFI_HANDLE);
>>      Status = gBS->LocateHandle (ByRegisterNotify,
>> -                                &gEfiDriverBindingProtocolGuid,
>> -                                mDriverEventRegistration,
>> +                                &gEfiI2cMasterProtocolGuid,
>> +                                mI2cMasterEventRegistration,
>>                                  &BufferSize,
>> -                                Handle);
>> +                                &Handle);
>>      if (EFI_ERROR (Status)) {
>>        if (Status != EFI_NOT_FOUND) {
>>          DEBUG ((DEBUG_WARN, "%a: gBS->LocateHandle () returned %r\n",
>> @@ -292,12 +292,7 @@ DriverRegistrationEvent (
>>        break;
>>      }
>>
>> -    //
>> -    // Check if we can connect our handle to this driver.
>> -    //
>> -    Handle[1] = NULL;
>> -    Status = gBS->ConnectController (mI2cMasterHandle, Handle, NULL, FALSE);
>> -    if (EFI_ERROR (Status)) {
>> +    if (Handle != mI2cMasterHandle) {
>>        continue;
>>      }
>>
>> @@ -378,16 +373,16 @@ LibRtcInitialize (
>>    ASSERT_EFI_ERROR (Status);
>>
>>    //
>> -  // Register a protocol registration notification callback on the driver
>> -  // binding protocol so we can attempt to connect our I2C master to it
>> -  // as soon as it appears.
>> +  // Register a protocol registration notification callback on the I2C master
>> +  // protocol. This will notify us even if the protocol instance we are looking
>> +  // for has already been installed.
>>    //
>>    EfiCreateProtocolNotifyEvent (
>> -    &gEfiDriverBindingProtocolGuid,
>> +    &gEfiI2cMasterProtocolGuid,
>>      TPL_CALLBACK,
>> -    DriverRegistrationEvent,
>> +    I2cMasterRegistrationEvent,
>>      NULL,
>> -    &mDriverEventRegistration);
>> +    &mI2cMasterEventRegistration);
>>
>>    //
>>    // Register for the virtual address change event
>> diff --git a/Silicon/NXP/Library/Pcf8563RealTimeClockLib/Pcf8563RealTimeClockLib.inf b/Silicon/NXP/Library/Pcf8563RealTimeClockLib/Pcf8563RealTimeClockLib.inf
>> index 1a9a6f6c9cf3..e232902c6b5d 100644
>> --- a/Silicon/NXP/Library/Pcf8563RealTimeClockLib/Pcf8563RealTimeClockLib.inf
>> +++ b/Silicon/NXP/Library/Pcf8563RealTimeClockLib/Pcf8563RealTimeClockLib.inf
>> @@ -40,7 +40,6 @@ [Guids]
>>    gEfiEventVirtualAddressChangeGuid
>>
>>  [Protocols]
>> -  gEfiDriverBindingProtocolGuid                   ## CONSUMES
>>    gEfiI2cMasterProtocolGuid                       ## CONSUMES
>>    gPcf8563RealTimeClockLibI2cMasterProtocolGuid   ## CONSUMES
>>
>> --
>> 2.11.0
>>