Dear zengshuai, zengshuai at sogou.com wrote: > i writed a led driver for PQ2FADS(a ppc board). > but i can't read/write 0x04500000 where led register addr locate in. > i tested two ways to do that. > first, > p=0x04500000; > *p=0x12; > .... > second, > outb(0x12,0x04500000); > ... > two ways both didn't work.they had a some wrong:kernel access of bad area. > how can i know which area is bad area or good area? > and what can i do next? thanks.
Do yourself a favor, read a book about Linux device driver development, for example one listed[1] in the excellent Denx's DLUG FAQ[2]. Getting some training on PowerPC development is a good idea too. [1] http://www.denx.de/wiki/view/DULG/MoreInformationBooks [2] http://www.denx.de/wiki/DULG/Manual Peruse also your chip data-sheet, and you will see that outb() is non-sense. If you are accessing the led register from kernel space, you'll find a solution using ioremap(). Otherwise, if you are accessing the led register from user space, this link[3] will help you, or this shorter one[4]. You can follow this thread[5] for more information. [3] http://www.denx.de/twiki/bin/view/PPCEmbedded/DeviceDrivers#Section_Acce ssingPeripheralsFromUserSpace [4] http://tinyurl.com/6c7th [5] http://lists.linuxppc.org/linuxppc-embedded/200403/msg00059.html Please next time, do ourselves a favor, try some searching first (google, whatever). Your question is a FAQ. Regards, -- Stephane
