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CellularModem » ModemProtocols » Samsung-ipc »

XMMUpstreaming » History » Version 8

Denis 'GNUtoo' Carikli, 01/31/2022 07:48 PM
Select Samsung-ipc as parent page because this is samsung-ipc specific

1 1 Denis 'GNUtoo' Carikli 
h1. XMMUpstreaming
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{{toc}}





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h2. Analysis of Replicant 9 Linux 5.2 modem branch





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These were cleaned up and ported from forkbomb's code:





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<pre>





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b4c2df98ed6f misc: xmm6262: Add Samsung IPC USB modem firmware download module





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77b55273bd6e net: usb: add Samsung IPC-over-HSIC driver





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f9ae2d1697fa net: add Samsung IPC interface driver





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7806adad4507 HACK: usb: host: ehci-exynos: add ehci_power sysfs node





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82c317b0da5e HACK: add modem power on/off driver





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28e5b460f920 HACK: usb: ehci_exynos: enable OHCI_SUSP_LEGACY





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e7c122b770c1 ARM: dts: EXYNOS: add 3G modem nodes to midas boards





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c3201527f7ea ARM: dts: split Exynos 4412 N710x boards up





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5b55f03cda8c ARM: dts: EXYNOS: add Samsung IPC modem support





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eca381876d5e ARM: dts: EXYNOS: enable HSIC0 on midas boards





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7ec9129e3221 replicant_*_defconfig: extend cmdline to get IMSI and other information





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54c196380507 replicant_*_defconfig: Add modem support





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[...]





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0ecfebd2b524 Linux 5.2





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</pre>





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If we look at the drivers only (not the dts or config changes, or hacks in pre-existing code, we are left with):





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<pre>





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b4c2df98ed6f misc: xmm6262: Add Samsung IPC USB modem firmware download module





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77b55273bd6e net: usb: add Samsung IPC-over-HSIC driver





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f9ae2d1697fa net: add Samsung IPC interface driver





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82c317b0da5e HACK: add modem power on/off driver





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</pre>





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We'd also need to find a way to fix these:





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<pre>





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7806adad4507 HACK: usb: host: ehci-exynos: add ehci_power sysfs node





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28e5b460f920 HACK: usb: ehci_exynos: enable OHCI_SUSP_LEGACY





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</pre>





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So we'd probably need to have something like that instead:





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    Denis 'GNUtoo'  Carikli
    
1. A driver for the SIPC (Samsung IPC) protocol (f9ae2d1697fa net: add Samsung IPC interface driver)





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2. A driver for the SIPC (Samsung IPC) transport on top of HSIC and the protocol (77b55273bd6e net: usb: add Samsung IPC-over-HSIC driver).





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    Denis 'GNUtoo'  Carikli
    
3. A modem driver with:





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** The GPIO handling like drivers/hsi/clients/nokia-modem.c (some GPIOs probably cannot be handled in userspace like gpio_pda_active (see [[XMMBoot#GPIOs-usage]] for more details) (82c317b0da5e HACK: add modem power on/off driver)





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** The firmware loading code (b4c2df98ed6f misc: xmm6262: Add Samsung IPC USB modem firmware download module)





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** Probably some of the hacks here. For instance GPIO input IRQ -> hsic bus reset





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So we have: Userspace <-> SIPC protocol <-> SIPC transport <-> HSIC





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However I'm not sure about certain things:





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* The SIPC protocol is huge and has different userspace interfaces. Maybe it could be split?





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* The SIPC transport driver uses an USB id table (the modem ID once booted). => Should we keep the IDs in it or move them in the modem driver instead?





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    Denis 'GNUtoo'  Carikli
    
Also look at the motorolla cpcap driver for the droid4. The architecture is different though: While it uses USB, it's tied to Qualcomm modem drivers (CDC) which probably doesn't have a specific protocol beside the multiplexing of the UART lines and network interfaces, though CDC could be seen as a specific protocol