[meta-xilinx] Recipes for MicroZed

[Nathan Rossi]

> -----Original Message-----
> From: meta-xilinx-bounces at yoctoproject.org [mailto:meta-xilinx-
> bounces at yoctoproject.org] On Behalf Of Anders Berndtsson
> Sent: Monday, January 13, 2014 10:11 PM
> To: meta-xilinx at yoctoproject.org
> Subject: [meta-xilinx] Recipes for MicroZed
> 
> Hallo all,
> 
> I have made recipes for the MiroZed board, based on the current Master
> branch.
> 
> During the development I had problem to access the SD cards.
> 
> Finally I found a solution at the Elphel project where the clocks
> frequency are changed in the device tree generator for the ps7_sd_0 as
> follows.
> 
> 
> 
>                                 ps7_sd_0: ps7-sdio at e0100000 {
> 
>                                                 clock-frequency =
> <0x7735940>;
> 
>                                                 clock-names = "ref_clk",
> "aper_clk";
> 
>                                                 clocks = <&clkc 21>,
> <&clkc 32>;
> 
>                                                 compatible = "xlnx,ps7-
> sdio-1.00.a", "generic-sdhci"  , "arasan,sdhci-8.9a";
> 
>                                                 interrupt-parent =
> <&ps7_scugic_0>;
> 
>                                                 interrupts = <0 24 4>;
> 
>                                                 reg = <0xe0100000 0x1000>;
> 
>                                                 xlnx,has-cd = <0x0>;
> 
>                                                 xlnx,has-power = <0x0>;
> 
>                                                 xlnx,has-wp = <0x0>;
> 
>                                                 xlnx,sdio-clk-freq-hz =
> <0x3f93e10>;
> 
>                                 } ;
> 
> 
> 
> I have now following questions.
> 
> 1.       Why is it working with this frequencies? In Xilinx-Zynq manual
> max frequency for the SD core is 50Mhz and also the zedboard is using 50
> MHz.

For all Zynq boards in meta-xilinx we stick with 50 MHz and we do not have any issues. It is indeed interesting that you are having issues, but I suspect it may be board or card specific? Try a different brand/type of card and see if you get different results.

Unfortunately I don't know much about the MicroZed, does it have any external board or MIO changes such that it is forced to operate at a different clock?

> 
> 2.       On the zed board the WP and CD are connected to MDIO 46 and 47,
> on microzed there is no WP and CD is connected to MDIO 46. In the device
> tree generator I disabled all signals but it seems that the CD works
> anyway, how come?

The "xlnx,has-cd" and "xlnx,has-wp" properties are not actually used by the Linux kernel, they are merely generated from the device tree generator as the information is available.

Check the drivers there may be a different property you can use to disable WP. Although I imagine just disabling it via the MIO is enough?

> 
> 3.       Where can I find the source code for the ps7_sd_0 driver?

Depends on which kernel you are using, the newer kernels use the arasan driver, older kernels use the xilinxps driver.

https://github.com/Xilinx/linux-xlnx/blob/xlnx_3.8/drivers/mmc/host/sdhci-of-xilinxps.c
https://github.com/Xilinx/linux-xlnx/blob/master/drivers/mmc/host/sdhci-of-arasan.c


Regards,
Nathan

> 
> 
> 
> My images seems to work well and stable, but I'm a newbie for both linux
> and Yocto so I will not publish anything official.
> 
> If someone is interested to test out this recipes and do the work I'm glad
> to chair my code. Just send a mail.
> 
> 
> 
> Regards
> 
> Anders