[Linux bottom layer] u-boot EMMC driver

In the era of copycat phones, many young people may not be familiar with the fact that a SD card is installed on the phone for storage expansion. The current smartphones will have an EMMC chip soldered on the PCB board for large-capacity data storage, which is much more secure. If the phone is lost, there is no need to worry about the leakage of photos or data.

1. EMMC Features

- Compliant with JEDEC/MMC Standard Version 5.0

- Advanced 12-signal interface

- x1, x4 and x8 I/O, selectable by host

-SDR/DDR mode, up to 52MHz clock speed

-HS200/HS400 mode

-Command class: class 0 (basic); class 2 (blockread); class 4 (block write); class 5 (erase); class 6 (write protection); class 7 (lock card)

Follow the WeChat public account and reply “EMMC information” to download the chip manual package for free.

2. Block diagram, MMC controller and NAND storage;

3. MMC model parameters, corresponding selection table

4. Pin Description

Some pins marked with shading are valid pins, and other pins are left floating;

After reading the above, does the pin introduction feel very similar to that of an SD card? Yes, including the control commands, it is the same as an SD card, just treat it as an SD card and it will be OK;

5. Functional block diagram

Just deal with the above registers.

6. Hardware wiring diagram reference: 8-wire data transmission, fast speed;

7. Device Tree

mmc0: mmc@f0000000 {

u-boot,dm-pre-reloc;

pinctrl-0 = <&pinctrl_mmc0_clk_cmd_dat0 &pinctrl_mmc0_dat1_3

&pinctrl_mmc0_dat4_7 &pinctrl_mmc0_cd>; //IO pin definition, please refer to the hardware schematic diagram for details

vmmc-supply = <&vcc_mmc0_reg>; //Controller used

vqmmc-supply = <&vcc_3v3_reg>;

status = "okay";

slot@0 {

reg = <0>;

bus-width = <8>; //The number of data lines must be correct

cd-gpios = <&pioE 0 GPIO_ACTIVE_LOW>; //

};

};

8. Usage Summary

EMMC chips, I have used Samsung chips, as well as some domestic EMMCs, all have a common feature, that is, the models are updated very quickly. After a few months, it is found that the chips from the previous batch are no longer available and are no longer in production. Here I would like to remind you that if you use EMMC to make products, it is best to stock more, or compare the parameters in the selection to find manufacturers and models with better replacement.