1 Scope of Document
This document describes TF hardware design
2 Requiremen
2.1 Function Requirement
Enumerate tf card , support boot from tf and can mount in rootfs when nand boot.
2.2 Performance Requirement
Support common capacity tf card
3 Hardware Overview
tf interface,pin map:
// data signal
AM335X_MMC0_DAT3----------MMC0_DAT3
AM335X_MMC0_DAT2----------MMC0_DAT2
AM335X_MMC0_DAT1----------MMC0_DAT1
AM335X_MMC0_DAT0----------MMC0_DAT0
// clk/cmd signal
AM335X_MMC0_CLK-----------MMC0_CLK
AM335X_MMC0_CMD----------MMC0_CMD
// card detect signal
AM335X_MCASP0_ACLK-----MCASP0_ACLKR (gpio3_18)
Figure 1 tf interface block diagram
4 Functional Description
4.1 Functional Block Diagram
Figure 2 inter block diagram
4.2 TF
4.2.1 Overview
AM335x has 3 instances MMC/SD/SDIO host controller, which provides an interface between microprocessor and either MMC, SD memory cards, or SDIO cards.
The MMC/SD driver is implemented as a block driver on top of host controller as a HSMMC controller driver and supports SD, SD High Speed and SDHC cards. The driver only supports for 4 bit modes(no SPI mode, 1/8 Bit). Both DMA & polled mode of data transfer is supported.
5 Porting
5.1 Uboot porting
Index: u-boot-2018.01/include/configs/am335x_evm.h
===================================================================
--- am335x_evm.h (revision 4)
+++ am335x_evm.h (revision 5)
@@ -17,6 +17,7 @@
#define __CONFIG_AM335X_EVM_H
#include <configs/ti_am335x_common.h>
+#define CONFIG_SD_BOOT
#ifndef CONFIG_SPL_BUILD
# define CONFIG_TIMESTAMPKernel porting
Nand to do pin mux in board/ti/am335x/mux.c
configure_module_pin_mux(mmc0_pin_mux_sk_evm);
5.2 Kernel porting
Device Drivers --->
<*> MMC/SD/SDIO card support --->
<*> MMC block device driver
<*> TI OMAP High Speed Multimedia Card Interface support
<M> MMC/SD/SDIO card support --->
<M> MMC block device driver
<M> TI OMAP High Speed Multimedia Card Interface support
Dts file change:
regulators {
compatible = "simple-bus";
vcc3v3: fixedregulator1 {
compatible = "regulator-fixed";
regulator-name = "vcc3v3";
regulator-min-microvolt = <3300000>;
regulator-max-microvolt = <3300000>;
regulator-boot-on;
};
};
mmc1_pins: pinmux_mmc1_pins {
pinctrl-single,pins = <
AM33XX_IOPAD(0x8fc, PIN_INPUT_PULLUP | MUX_MODE0) /* mmc0_dat0.mmc0_dat0 */
AM33XX_IOPAD(0x8f8, PIN_INPUT_PULLUP | MUX_MODE0) /* mmc0_dat1.mmc0_dat1 */
AM33XX_IOPAD(0x8f4, PIN_INPUT_PULLUP | MUX_MODE0) /* mmc0_dat2.mmc0_dat2 */
AM33XX_IOPAD(0x8f0, PIN_INPUT_PULLUP | MUX_MODE0) /* mmc0_dat3.mmc0_dat3 */
AM33XX_IOPAD(0x904, PIN_INPUT_PULLUP | MUX_MODE0) /* mmc0_cmd.mmc0_cmd */
AM33XX_IOPAD(0x900, PIN_INPUT_PULLUP | MUX_MODE0) /* mmc0_clk.mmc0_clk */
AM33XX_IOPAD(0x9a0, PIN_INPUT_PULLUP | MUX_MODE7) /* mcasp0_aclkr.mmc0_sdwp */
>;
};
&mmc1 {
status = "okay";
/*vmmc-supply = <&vmmc_reg>;*/
vmmc-supply = <&vcc3v3>;
bus-width = <4>;
pinctrl-names = "default";
pinctrl-0 = <&mmc1_pins>;
cd-gpios = <&gpio3 18 GPIO_ACTIVE_LOW>;
};
[ 1.272256] omap_hsmmc 48060000.mmc: using lookup tables for GPIO lookup
[ 1.272266] omap_hsmmc 48060000.mmc: lookup for GPIO wp failed
[ 1.513463] mmc0: host does not support reading read-only switch, assuming write-enable
[ 1.532796] mmc0: new high speed SDHC card at address 0007
[ 1.542753] mmcblk0: mmc0:0007 SD16G 14.5 GiB
[ 1.554116] mmcblk0: p1
6 Follow-up
We can do some optimize: for example fs check function
Manual fs check :
root@am335x-evm:~# fsck /dev/mmcblk0p1
fsck from util-linux 2.30
CP437: Invalid argument
fsck.fat 4.1 (2017-01-24)
0x41: Dirty bit is set. Fs was not properly unmounted and some data may be corrupt.
1) Remove dirty bit
2) No action
? 1
Perform changes ? (y/n) y
/dev/mmcblk0p1: 10 files, 35768/1901241 clusters
Auto fs check:
root@am335x-evm:/etc# vi /etc/fstab
# stock fstab - you probably want to override this with a machine specific one
/dev/root / auto defaults 1 1
proc /proc proc defaults 0 0
devpts /dev/pts devpts mode=0620,gid=5 0 0
usbdevfs /proc/bus/usb usbdevfs noauto 0 0
tmpfs /run tmpfs mode=0755,nodev,nosuid,strictatime 0 0
tmpfs /var/volatile tmpfs defaults,size=50M 0 0
tmpfs /media/ram tmpfs defaults,size=16M 0 0
# uncomment this if your device has a SD/MMC/Transflash slot
/dev/mmcblk0p1 /media/card auto defaults,sync,noauto 0 1