Hi Oleksandr, On Thu, Sep 28, 2017 at 10:53 AM, Oleksandr Shamray <oleksandrs@xxxxxxxxxxxx> wrote: >> [My attention was drawn by >> https://emea01.safelinks.protection.outlook.com/?url=https%3A%2F%2Flwn.net >> %2FArticles%2F734440%2F&data=02%7C01%7Coleksandrs%40mellanox.com%7 >> C97b8ba88686a42daaace08d5064b92eb%7Ca652971c7d2e4d9ba6a4d149256f >> 461b%7C0%7C0%7C636421844026854216&sdata=TeHD4a3%2FBN6a5XG3Jizf5 >> pmsyJHJjzkEzkpnqsXC6S0%3D&reserved=0] >> [CC linux-spi, which was never included, while linux-serial was] >> >> On Thu, Sep 21, 2017 at 11:25 AM, Oleksandr Shamray >> <oleksandrs@xxxxxxxxxxxx> wrote: >> > When a need raise up to use JTAG interface for system's devices >> > programming or CPU debugging, usually the user layer application >> > implements jtag protocol by bit-bang or using a proprietary connection >> > to vendor hardware. >> > This method can be slow and not generic. >> > > > > [..] > >> > >> > Initial version provides the system calls set for: >> > - SIR (Scan Instruction Register, IEEE 1149.1 Data Register scan); >> > - SDR (Scan Data Register, IEEE 1149.1 Instruction Register scan); >> > - RUNTEST (Forces the IEEE 1149.1 bus to a run state for a specified >> > number of clocks. >> > >> > SoC which are not equipped with JTAG master interface, can be built on >> > top of JTAG core driver infrastructure, by applying bit-banging of >> > TDI, TDO, TCK and TMS pins within the hardware specific driver. >> >> Or by using an SPI master? >> > > I think it depends on how flexible the SPI interface is. If you can set it to transfer > from 1 to n bits at a time, and you control the TMS line in software, you should > be able to use it. If the SPI interface can only transfer a multiple of 8 bits > at a time, then in general it would not be suitable for JTAG. Sure, that depends on the actual SPI master interface. But I guess you can write a generic JTAG-over-SPI driver, and use a tms-gpios property in DT to specify how to control TMS. Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
