UM0851 datasheet(140/245 Pages) STMICROELECTRONICS

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Non-volatile memory device drivers

UM0851

140/245

Doc ID 16604 Rev 2

For transactions that are not supported, an AHB Error is generated on the bus and an

interrupt is raised. The interrupt flag can be checked in the IRQ register.

The data phase (the data bus along with the control signals) is extended until the EMI_ACK#

is asserted low by the external peripheral. If this feature is not used (depending on the

configuration in the Ack_reg), this signal is ignored.

5.2.2

Software overview

The EMI driver handles the initialization and timing settings for the EMI controller. The

parallel NOR Flash driver is a application sample based on the EMI driver. The parallel NOR

Flash driver is a part of the Common Flash Interface driver and provides all necessary

functions for a filesystem via the standard Linux MTD interface.

Figure 36.

EMI system software architecture

Once U-Boot and Linux startup has completed, the EMI driver attempts to initialize the bus

bandwidth and acknowledge signal functionality of the EMI controller according to the

system boot option. Its timing is set based on a table in U-Boot.

const struct cust_emi_para emi_timing_m28w640hc = {

.tap

= 0x10,

.tsdp

= 0x05,

.tdpw

= 0x0a,

8 bit

32 bit

No (AHB Error, Interrupt)

8 bit

16 bit

No (AHB Error, Interrupt)

8 bit

Yes

Table 40.

Supported transactions

Peripheral connected

AHB access

Support

CFI driver

NAND driver

Linux MTD layer

YAFFS2

JFFS2

VFS

FSMC

EMI

controller

Application

User space

Kernel space

Hardware

NOR

Flash

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