Linux Kernel MMC Storage driver Overview

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Outline
0 Storage Devices on mobile platform
(smart phones, tablets etc.)
0 RAM
0 Internal Storage Devices
0 External Stor...

Storage Devices on Mobile Platforms
0 Mobile Platforms will have mainly Three storage devices for applications/users to
st...

What is Flash Memory ?
0 Flash Memory is a non-volatile, solid state storage device i.e. keeps
its data without power.
0 F...

Internal Storage Device
0 Internal Storage mostly holds the android operating
system so that the android device is able to...

Internal Storage Devices
0 Following are the storage devices which are mainly used for
main storage devices on mobile plat...

External Storage Device
0 Android devices may support
the capability of adding more
external storage via removable
cards l...

How to identify SD card’s class?
Preferable card: class 10 or UHS-I cards
Class
Minimum
Serial Data
Writing
Speed
Symbol o...

SD Memory card architecture
Card Info
registers
Usage
CID Card identification number
RCA Relative card address published b...

SD and SPI protocol
SPI Protocol SD Protocol
Design simple Complex
Loss of performance: 1bit mode Wide bus option. Support...

Storage Device Driver for
eMMC and SD devices
0 Storage Device Driver ($kernel/drivers/mmc) is common
for eMMC devices (in...

mmc Device Driver Top View
Kernel
Space
User Space
Virtual File System Layer
Generic Block Layer
mmc device driver
Hardwar...

mmc Device Driver block diagram
Kernel
Space
Virtual File System Layer
Generic Block Layer
Hardware
devices
eMMC device SD...

mmc device driver overview
0 mmc queue receives block read/write/erase
requests from the generic core block layer
0 mmc qu...

mmc queue layer
(/drivers/mmc/card/queue.c)
0 Important functions:
0 mmc_init_queue()
0 initializes the device queue
0 Cre...

mmc block layer (/drivers/mmc/card/block.c)
0 Important functions: 1) mmc_blk_probe()
0 Calls the mmc_queue_initialize() t...

mmc core layer
(/drivers/mmc/core/*)
0 It Implements all SD/eMMC-dependent functionality, entire
communication protocol is...

mmc host layer (drivers/mmc/host/*)
0 It implements the driver for most known platform controllers and
is platform depende...

SD Host controller role @Data Transfer
0 Data location of system memory  DMA_SYSTEM_ADDR (If DMA supported)
0 Set Block s...

Mmc driver features
0 Host-Device interface is reliable when FREQ limits upto 50MHz
0 SD: High speed (HS) SD cards, class ...

SDMMC devices registration
0 Device registration requires both device name and driver name should
match
0 Device registrat...

SDHCI probe()
Probe() is called when device is recognized by the platform
Driver’s init function gives kernel a list of de...

How to enable SDHCI controller:
MMC/SD Card support Configuration
0 Configure below variables for mmc devices (eMMC
and SD...

Conclusion
0 eMMC device is used for internal storage on mobile platforms
0 SD device (external SD cards) is used for exte...

References
1. Wikipedia:
https://en.wikipedia.org/wiki/Secure_Digital
2. TEACH-ICT – The very best KS3, GCSE and A Level
C...

THANK YOU 
Have a look at
My PPTs:
http://www.slideshare.net/rampalliraj/
My Blog: http://practicepeople.blogspot.in/

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Q4.11: Introduction to eMMC by Linaro 60994 views

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