How to interface a second sd card (that operates in SPI mode) under the 4.1 kernel?

[thom...@googlemail.com]

I am using the Digilent PmodSD as the second sd card for the BBB: http://www.digilentinc.com/Products/Detail.cfm?Prod=PMOD-SD

I've been following this forum: http://www.alteraforum.com/forum/showthread.php?t=19335&page=4

but assumes that i have the mmc_spi driver, which isnt found in the 4.1.2-ti-r4 kernel on my beaglebone: mmc_spi.c source file doesnt exist also.

root@beaglebone:~# find /lib/modules/`uname -r` -type f -name "*.ko" | grep mmc

/lib/modules/4.1.2-ti-r4/kernel/drivers/media/mmc/siano/smssdio.ko
/lib/modules/4.1.2-ti-r4/kernel/drivers/mmc/host/sdhci.ko
/lib/modules/4.1.2-ti-r4/kernel/drivers/mmc/host/vub300.ko
/lib/modules/4.1.2-ti-r4/kernel/drivers/mmc/host/dw_mmc-exynos.ko
/lib/modules/4.1.2-ti-r4/kernel/drivers/mmc/host/dw_mmc-pltfm.ko
/lib/modules/4.1.2-ti-r4/kernel/drivers/mmc/host/ushc.ko
/lib/modules/4.1.2-ti-r4/kernel/drivers/mmc/host/dw_mmc.ko
/lib/modules/4.1.2-ti-r4/kernel/drivers/mmc/host/sdhci-pltfm.ko
/lib/modules/4.1.2-ti-r4/kernel/drivers/mmc/host/rtsx_usb_sdmmc.ko
/lib/modules/4.1.2-ti-r4/kernel/drivers/mmc/card/sdio_uart.ko

 root@beaglebone:~# find /lib/modules/`uname -r` -type f -name "*.ko" | grep spi

/lib/modules/4.1.2-ti-r4/kernel/drivers/misc/ad525x_dpot-spi.ko
/lib/modules/4.1.2-ti-r4/kernel/drivers/spi/spi-butterfly.ko
/lib/modules/4.1.2-ti-r4/kernel/drivers/spi/spi-lm70llp.ko
/lib/modules/4.1.2-ti-r4/kernel/drivers/spi/spi-omap2-mcspi.ko
/lib/modules/4.1.2-ti-r4/kernel/drivers/mtd/spi-nor/spi-nor.ko
/lib/modules/4.1.2-ti-r4/kernel/drivers/scsi/scsi_transport_spi.ko
/lib/modules/4.1.2-ti-r4/kernel/drivers/net/wireless/ti/wl1251/wl1251_spi.ko
/lib/modules/4.1.2-ti-r4/kernel/drivers/net/wireless/ti/wlcore/wlcore_spi.ko
/lib/modules/4.1.2-ti-r4/kernel/drivers/net/can/spi/mcp251x.ko
/lib/modules/4.1.2-ti-r4/kernel/drivers/mfd/mc13xxx-spi.ko

 In another forum, a person solved this by actually interfacing the second SD to the mmc lines:  SPI-SD Card

I dont see how this will work since mmc1 lines on the p8 header are used by the board. And when i wire my sd card to these lines the Beaglebone doesnt boot up.  Also the mmc2 on the p8 header doesnt have a cmd mode pin (mmc2_cmd), so i cant use these lines.  There are another set of mmc2 lines on the p9 header but its also missing a mmc2_cmd and a  mmc2_clk mode pin. 

  Any insight on how to add a second SD card?

[Robert Nelson]

CONFIG_HIGHMEM=y i set...

472 config MMC_SPI
473 tristate "MMC/SD/SDIO over SPI"
474 depends on SPI_MASTER && !HIGHMEM && HAS_DMA
475 select CRC7
476 select CRC_ITU_T
477 help
478 Some systems access MMC/SD/SDIO cards using a SPI controller
479 instead of using a "native" MMC/SD/SDIO controller. This has a
480 disadvantage of being relatively high overhead, but a compensating
481 advantage of working on many systems without dedicated MMC/SD/SDIO
482 controllers.
483
484 If unsure, or if your system has no SPI master driver, say N.

So rebuild the kernel without HIGHMEM, then you can enable MMC_SPI..

Regards,

--
Robert Nelson
https://rcn-ee.com/

[Robert Nelson]

Note it's been depended on !HIGHMEM since it's initial upstreaming..

https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=15a0580ced081a0f7dc2deea8a4812bdc5e9a109

[thom...@googlemail.com]

I've managed to disable HIGHMEM from within the kernel.  However im having trouble compiling.  The usual 'make clean' and 'make all' gives me errors:

root@beaglebone:/usr/src/linux-headers-4.1.2-ti-r4# make all

  CHK     include/config/kernel.release

  UPD     include/config/kernel.release

  CHK     include/generated/uapi/linux/version.h

  CHK     include/generated/utsrelease.h

  UPD     include/generated/utsrelease.h

make[1]: *** No rule to make target 'arch/arm/tools/gen-mach-types', needed by 'include/generated/mach-types.h'.  Stop.

arch/arm/Makefile:297: recipe for target 'archprepare' failed

make: *** [archprepare] Error 2

How do i compile the kernel with the changes made to .config?

[Robert Nelson]

On Tue, Aug 4, 2015 at 7:32 PM, <thom...@googlemail.com> wrote:
> I've managed to disable HIGHMEM from within the kernel. However im having
> trouble compiling. The usual 'make clean' and 'make all' gives me errors:
>
> root@beaglebone:/usr/src/linux-headers-4.1.2-ti-r4# make all
> CHK include/config/kernel.release
> UPD include/config/kernel.release
> CHK include/generated/uapi/linux/version.h
> CHK include/generated/utsrelease.h
> UPD include/generated/utsrelease.h
> make[1]: *** No rule to make target 'arch/arm/tools/gen-mach-types', needed
> by 'include/generated/mach-types.h'. Stop.
> arch/arm/Makefile:297: recipe for target 'archprepare' failed
> make: *** [archprepare] Error 2

Sorry, that's "headers"....

> root@beaglebone:/usr/src/linux-"headers"-4.1.2-ti-r4# make all

Grab the source via:

git clone -b 4.1.2-ti-r4 https://github.com/beagleboard/linux --depth=1

[thom...@googlemail.com]

RCNelson, Thanks for you help so far.

When trying to compile the 4.1 kernel i'm running into an ftrace error:

...

arch/arm/kernel/ftrace.c: In function ‘ftrace_arch_code_modify_post_process’:

arch/arm/kernel/ftrace.c:93:2: error: implicit declaration of function ‘flush_tlb_all’ [-Werror=implicit-function-declaration]

  flush_tlb_all();

  ^

cc1: some warnings being treated as errors

scripts/Makefile.build:258: recipe for target 'arch/arm/kernel/ftrace.o' failed

make[1]: *** [arch/arm/kernel/ftrace.o] Error 1

Makefile:946: recipe for target 'arch/arm/kernel' failed

make: *** [arch/arm/kernel] Error 2

Is there any kernel patch i can install to fix this error?

Also I decided to use the mmc2 lines for the sd card instead of using the spi bus.  I believe that the pin configuration is correct but the beaglebone is still not detecting the sd card.

In the am335x-bone-common.dtsi file:

mmc2_pins: pinmux_mmc2_pins {

                pinctrl-single,pins = <

                        0x078 (PIN_OUTPUT_PULLUP | MUX_MODE3)           /* mmc2_dat3---CS, p9_12*/

                        0x044 (PIN_INPUT_PULLUP | MUX_MODE3)            /* mmc2_dat0---DO---MISO, p9_23 */

                        0x088 (PIN_OUTPUT_PULLUP | MUX_MODE3)           /* mmc2_cmd---T13---MOSI */

                        0x08c (PIN_OUTPUT_PULLUP | MUX_MODE3)           /* mmc2_clk, p8_18 */

                        0x040 (PIN_OUTPUT_PULLUP | MUX_MODE7)           /* R13 which is tied to T13, p9_15*/

                        0x074 (PIN_INPUT_PULLUP | MUX_MODE4)            /* mmc2_sdcd, p9_13 */

                        0x048 (PIN_INPUT_PULLUP | MUX_MODE3)            /* mmc2_dat1, p9_14 */

                        0x04c (PIN_INPUT_PULLUP | MUX_MODE3)            /* mmc2_dat2, p9_16 */

                >;

        };

&mmc2 {

        status = "okay";

        bus-width = <0x4>;

        pinctrl-names = "default";

        pinctrl-0 = <&mmc2_pins>;

};

I figured out that mmc2_cmd pin is the T13 ZCZ Ball: http://www.ti.com/product/AM3358/datasheet/terminal_configuration_and_functions#bc_15x15_T13

and that the T13 line is tied to the R13 line, so i configured R13 to GPIO output pullup and T13 as mode 3 output pullup. 

Is there anything else in the device tree that needs to be edited in order to get mmc2 detected by the OS on the beaglebone?