From mboxrd@z Thu Jan  1 00:00:00 1970
From: greg@kroah.com (Greg KH)
Date: Mon, 25 Jun 2018 08:50:20 +0800
Subject: How kernel derive irq number for particular irq line
In-Reply-To: <CAHJZ6qFmUOSXvqxAR9bt4c+0VK4B7a75bijZnJeL2WqhEN70Og@mail.gmail.com>
References: <CAHJZ6qFmUOSXvqxAR9bt4c+0VK4B7a75bijZnJeL2WqhEN70Og@mail.gmail.com>
Message-ID: <20180625005020.GA23869@kroah.com>
To: kernelnewbies@lists.kernelnewbies.org
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On Mon, Jun 25, 2018 at 12:17:06AM +0530, Abhinav Misra wrote:
> Hi Guys,
> 
> I want to know how the irq number is derived in linux kernel.

It all depends on your platform.  It either comes from the firmware/bios
or it is in the device tree information.  The kernel itself doesn't know
this information, it has to be told that from an external source.

Hope this helps,

greg k-h