Direct Interface to Compact Flash

Oct 10, 2005 1 Replies
G

I am writing software for an embedded Linux system that has a compact flash device directly wired to a general-purpose peripheral bus. This is a PowerPC 440GP-based system. The IDE interface chip select will appear at some physical memory location that I program into the peripheral bus controller.



Is there a standard way to configure a Linux IDE driver to recognize this memory-mapped IDE device? It seems that the ide driver in Linux wants to talk to an IDE interface chip rather than directly to an IDE device. For example, Documentation/ide.txt refers to IDE chipsets, I/O ports, and the PCI bus.



Thanks,



Gregg


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G

I've do last year somethings like that. I've written a little driver that listen to an input port, detecting the insertion of a CF in the slot. When it detects a device, look at the CIS structure and, if classified as an IDE disk, do the following:

Sets the CF register to IO mapper or memory mapped mode. Based on this choice (depends on your hardware), calls:

#include .... #if CF_ACCESS_MODE == CF_MEMORY_MODE cf_hd = ide_register ( CFMEM_BASE, CFMEM_BASE8+0x00E, IRQ_COMPACTFLASH ); #endif #if CF_ACCESS_MODE == CF_IOMODE_CONTINUOUS cf_hd = ide_register ( CFIO_BASE, CFIO_BASE8+0xE, IRQ_COMPACTFLASH ); #endif

#if CF_ACCESS_MODE == CF_IOMODE_PRIMARY cf_hd = ide_register ( CFIO_BASE+x1F0, CFIO_BASE8+0x3F6, IRQ_COMPACTFLASH ); #endif

#if CF_ACCESS_MODE == CF_IOMODE_SECONDARY cf_hd = ide_register ( CFIO_BASE+0x170, CFIO_BASE8+0x376, IRQ_COMPACTFLASH ); #endif

CFIO_BASE is the base address to reach your device. The offsets depends on your bus with (8, 16 or 32). CF_IOMODE_xxxx must be defined depending on CF modality IRQ_COMPACTFLASH is the irq.

This works fine in a 2.4.18 kernel. I hope that may help. By Gabriele

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