On Wed, Aug 11, 2010 at 9:45 PM, MJ embd <mj.e...@gmail.com> wrote: > u can directly access GPIO registers in kernel, by ioremap of GPIO > memory mapped registers. > you might need to check > - muxing of gpio > > -mj >
Hi MJ, Thanks for the reply. I tried memory mapping but it fails, here is my code : #include <linux/module.h> #include <linux/errno.h> /* error codes */ #include <linux/mm.h> void __iomem *ioaddr = NULL; static __init int sample_module_init(void) { ioaddr = ioremap(0xFF400C00, 0x24); if(ioaddr == NULL) { printk(KERN_WARNING "ioremap failed\n"); } printk(KERN_WARNING "ioremap successed\n"); printk(KERN_WARNING "GP1DIR = %u\n", ioread32(ioaddr)); return 0; } static __exit void sample_module_exit(void) { iounmap(ioaddr); } MODULE_LICENSE("GPL"); module_init(sample_module_init); module_exit(sample_module_exit); As per the MPC8377ERDB data sheet default IMMRBAR address is 0xFF40_0000 and offset of GPIO1 is 0C00 and each GPIO has programmable registers that occupy 24 bytes of memory-mapped space, so I mapped from 24bytes (0x18) starting from 0xFF40_0C00 address. But when I tried to read the values from the mapped memory I get the following errors. Is there something I am missing. Any help with reference to MPC8377ERDB board will be highly appreciable. # tftp -l ~/immrbar.ko -r immrbar.ko -g 10.20.50.70 # insmod ./immrbar.ko [ 717.825241] ioremap successed [ 717.849215] Machine check in kernel mode. [ 717.853220] Caused by (from SRR1=41000): Transfer error ack signal [ 717.859405] Oops: Machine check, sig: 7 [#1] [ 717.863668] MPC837x RDB [ 717.866106] Modules linked in: immrbar(+) [ 717.870119] NIP: 00000900 LR: d1034054 CTR: c0014d50 [ 717.875079] REGS: cf895d00 TRAP: 0200 Not tainted (2.6.28.9) [ 717.880992] MSR: 00041000 <ME> CR: 24000082 XER: 20000000 [ 717.886578] TASK = cf8e8640[647] 'insmod' THREAD: cf894000 [ 717.891882] GPR00: d103404c cf895db0 cf8e8640 00000000 000023d5 ffffffff c01e 04f4 00020000 [ 717.900265] GPR08: 00000001 c0383f3c 000023d5 c0014d50 4c72ff56 10019100 1007 77e0 1007ea98 [ 717.908650] GPR16: 10077834 100a0000 100a0000 100a0000 bfaf4828 00000000 1009 f23c 10000cfc [ 717.917034] GPR24: 10000d00 10000d24 10012008 c03650e8 00000000 d1034000 1001 2018 d1030000 [ 717.925598] NIP [00000900] 0x900 [ 717.928828] LR [d1034054] sample_module_init+0x54/0xc0 [immrbar] [ 717.934828] Call Trace: [ 717.937273] [cf895db0] [d103404c] sample_module_init+0x4c/0xc0 [immrbar] (unr eliable) [ 717.945115] [cf895dc0] [c00038a0] do_one_initcall+0x64/0x18c [ 717.950780] [cf895f20] [c004d7b8] sys_init_module+0xac/0x19c [ 717.956441] [cf895f40] [c00122f0] ret_from_syscall+0x0/0x38 [ 717.962013] --- Exception: c01 at 0x48043f6c [ 717.962017] LR = 0x100009cc [ 717.969407] Instruction dump: [ 717.972370] 00000000 XXXXXXXX XXXXXXXX XXXXXXXX 00000000 XXXXXXXX XXXXXXXX XX XXXXXX [ 717.980140] 00000000 XXXXXXXX XXXXXXXX XXXXXXXX 7d5043a6 XXXXXXXX XXXXXXXX XX XXXXXX [ 717.987919] ---[ end trace a47be794e2873cef ]--- Thanks in advance Ravi Gupta
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