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Date:      Wed, 3 Jun 2020 17:29:26 +0300
From:      Andriy Gapon <avg@FreeBSD.org>
To:        Rajesh Kumar <rajfbsd@gmail.com>, freebsd-drivers@freebsd.org, FreeBSD Hackers <freebsd-hackers@freebsd.org>
Subject:   Re: Can we hook a device as device to two different parent devices?
Message-ID:  <c1b611bc-4fa7-7975-da3f-e7c68a26e92b@FreeBSD.org>
In-Reply-To: <CAAO%2BANOB8m6OjRY-FOVVHQi3vdcCEnHdjE2s3xoHdh0rjaTruQ@mail.gmail.com>
References:  <CAAO%2BANOB8m6OjRY-FOVVHQi3vdcCEnHdjE2s3xoHdh0rjaTruQ@mail.gmail.com>

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On 03/06/2020 14:20, Rajesh Kumar wrote:
> Hi,
> 
> Is it really possible to declare a module with two parents? Like the
> following declarations in the same driver.
> 
> devclass_t test_dev_devclass;
> static DEFINE_CLASS_0(test_dev, test_dev_driver, test_dev_methods,
> sizeof(struct test_dev_ctx));
> DRIVER_MODULE(test_dev, *device1*, test_dev_driver, test_dev_devclass,
> NULL, NULL);
> DRIVER_MODULE(test_dev, *device2*, test_dev_driver, test_dev_devclass,
> NULL, NULL);
> 
> I see similar references in other drivers attaching to both simpleus and
> ofwbus. So, If it's possible, how to get the reference for both the
> parents?  device_get_parent(test_dev) will give reference of one parent
> only right, so how to get the reference of the desired parent?

A device can have only one parent.
The declaration you quoted describes a _driver_ that can attach to devices
hanging off two different buses.  They would still be different devices.


-- 
Andriy Gapon



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