User:Knuxify/Draft:Qualcomm/Adding a new SoC to mainline Linux: Difference between revisions
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In order to begin mainlining your SoC, you need to have the following bits of information: | In order to begin mainlining your SoC, you need to have the following bits of information: | ||
* The | * The '''codenames''' of the SoC. Qualcomm SoCs appear to have two codenames<ref>The names of these codenames have been sourced from [https://wiki.postmarketos.org/wiki/Qualcomm_Snapdragon_8_Gen_1/8%2B_Gen_1/7%2B_Gen_2_(SM8450/SM8475/SM7475) the postmarketOS wiki page for the Snapdragon 8 Gen 1], not sure where that is sourced from.</ref>: | ||
* A copy of the downstream kernel; preferably the one for your device, but you can also use the kernel from another device with the same SoC, or - as a last resort - any kernel with the relevant SoC drivers (hint: search by codename). | ** '''Board codename''' ("DTS nickname"?) - you'll find it in the driver names on the device, as well as in the main compatible string of the devicetree. This is what's used across most of the downstream kernel. | ||
* A copy of the <code>qcom_proprietary_devicetree</code> or similar repo with the DTSI source files (because they're not in the kernel repo for whatever reason...). Search for <code>(codename).dtsi</code> on GitHub and you'll find the right repository eventually. | ** '''Platform codename''' - presumably shared between multiple SoCs from the same family. | ||
* An extracted DTB from your device. Dump this from a running device using FDT (todo: instructions, would probably be good on a generic page, maybe subpage of [[Devicetree]]? | ** Since SM7635 ("Volcano"/"Milos") getting upstreamed, Qualcomm appears to have changed their policy around driver/compatible naming in mainline and now expects developers to use the platform codename instead of the model number<ref>https://lore.kernel.org/lkml/[email protected]/</ref>. If you're unsure of the platform codename for your device, you can send the Qualcomm folks an email and ask them directly<ref>I ended up getting [https://lore.kernel.org/lkml/c379aad4-96f6-4134-8b90-[email protected]/ a public reply to my query for SM7435].</ref>, or just use the model name for now and let them correct you (as was done in the Milos case). | ||
* Find a similar SoC that is already supported. Usually flagship SoCs are available in mainline; try to find a flagship from around the same time as the SoC you're mainlining. Find its DTSIs as well; then you can compare the differences between downstream and mainline for the upstreamed SoC, and correlate them with differences in your SoC. | * A copy of the '''downstream kernel'''; preferably the one for your device, but you can also use the kernel from another device with the same SoC, or - as a last resort - any kernel with the relevant SoC drivers (hint: search by downstream codename). | ||
* A copy of the '''<code>qcom_proprietary_devicetree</code>''' or similar repo with the DTSI source files (because they're not in the kernel repo for whatever reason...). Search for <code>(downstream codename).dtsi</code> on GitHub and you'll find the right repository eventually. | |||
* An '''extracted DTB from your device'''. Dump this from a running device using FDT (todo: instructions, would probably be good on a generic page, maybe subpage of [[Devicetree]])? | |||
* Find a similar SoC that is already supported. Usually flagship SoCs are available in mainline; try to find a flagship from around the same time as the SoC you're mainlining. Find its DTSIs as well; then you can compare the differences between downstream and mainline for the upstreamed SoC, and correlate them with differences in your SoC. You'll also be able to check the other SoC's drivers and use them as a base for your own drivers. | |||
== Adding the DTSI == | == Adding the DTSI == | ||
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Qualcomm devices use ''multiple'' PMICs for different purposes. Often, the PMIC is paired with an SoC or series of SoCs. | Qualcomm devices use ''multiple'' PMICs for different purposes. Often, the PMIC is paired with an SoC or series of SoCs. | ||
== References == | |||