* PPC beginner questions
@ 2006-08-21 13:51 Wade Maxfield
2006-08-21 14:14 ` Grant Likely
2006-08-22 8:53 ` David H. Lynch Jr.
0 siblings, 2 replies; 6+ messages in thread
From: Wade Maxfield @ 2006-08-21 13:51 UTC (permalink / raw)
To: ppc
[-- Attachment #1: Type: text/plain, Size: 778 bytes --]
I'm new to the PPC and I have a few questions. I have written a driver
in the past for the X86 family, using i/o ports, but it was kernel 2.0 and
i/o ports are not mmu handled.
I've been looking through the archive and I am slowly growing more
confused.
We are using Xilinx with PPC built in.
The PPC has a memory management unit. All of the IP we've added is
mapped to physical addresses.
1. Can I access the memory the peripherasl are mapped to directly within
the driver without going through functions?
if NOT, then Do I use
1. ioremap(),
2. request_mem_region(),
3. request_region()
4. something else?
2. Are there any gotcha's with the ppc 405 that Xilinx uses that I
should know about?
thanks,
wade
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^ permalink raw reply [flat|nested] 6+ messages in thread* Re: PPC beginner questions 2006-08-21 13:51 PPC beginner questions Wade Maxfield @ 2006-08-21 14:14 ` Grant Likely [not found] ` <45a1b53e0608210759p270c2f8dy694e91f409d57729@mail.gmail.com> 2006-08-22 8:53 ` David H. Lynch Jr. 1 sibling, 1 reply; 6+ messages in thread From: Grant Likely @ 2006-08-21 14:14 UTC (permalink / raw) To: Wade Maxfield; +Cc: ppc On 8/21/06, Wade Maxfield <wmaxfield@gmail.com> wrote: > > We are using Xilinx with PPC built in. > > The PPC has a memory management unit. All of the IP we've added is > mapped to physical addresses. > > 1. Can I access the memory the peripherasl are mapped to directly within > the driver without going through functions? No, you need to map them into virtual memory, then you can use the in* out* functions to read/write. (You can also directly use the virtual addresses as pointers, but in*/out* is more portable) > if NOT, then Do I use > 1. ioremap(), > 2. request_mem_region(), > 3. request_region() > 4. something else? ioremap > > 2. Are there any gotcha's with the ppc 405 that Xilinx uses that I > should know about? Yes, lots. :) Actually it's pretty straight forward. Mainline Linux 2.6 contains support for both the Virtex-II Pro and the Virtex 4, but not a lot of device drivers. The MontaVista 2.4 tree is supported by Xilinx with drivers, but then you have to use linux 2.4. :p Also, it's a good idea to read the Xilinx errata. have fun. g. -- Grant Likely, B.Sc. P.Eng. Secret Lab Technologies Ltd. grant.likely@secretlab.ca (403) 399-0195 ^ permalink raw reply [flat|nested] 6+ messages in thread
[parent not found: <45a1b53e0608210759p270c2f8dy694e91f409d57729@mail.gmail.com>]
* Re: PPC beginner questions [not found] ` <45a1b53e0608210759p270c2f8dy694e91f409d57729@mail.gmail.com> @ 2006-08-21 15:38 ` Grant Likely 2006-08-21 16:07 ` Wade Maxfield 0 siblings, 1 reply; 6+ messages in thread From: Grant Likely @ 2006-08-21 15:38 UTC (permalink / raw) To: Wade Maxfield; +Cc: linuxppc-embedded list On 8/21/06, Wade Maxfield <wmaxfield@gmail.com> wrote: > Hi Grant, > > Thanks! > > in* > out* > > I'm assuming inb() outb(), inw() outw()?? I've been googling and have > come up short with info that makes sense. It is almost all x86 centric. in_8, in_be16, in_be32, out_8, out_be16, out_be32 for big-endian device registers in_8, in_le16, in_le32, out_8, out_le16, out_le32 for little endian device registers > > We will not be porting these drivers, this is a captive box internal use > only, limited run (200 units or so), 10 to 20 year lifespan once it hits the > field. > > So, the virtual address I get back can be used directly. Can I cast to > short * and long * and char *? heh, yes you can; but if your writing new code why not use good practice from the start? :) > > I apologize for the basic questions, but I expect this will be a final > question for quite some time. No worries; ask away! Cheers, g. BTW, when on the mailing list, please use "reply to all" and put your comments below what you're commenting on. This keeps the thread on the mailing list for others to see, and it makes it blatentely obvious what you're commenting on. (just general list-etiquette) -- Grant Likely, B.Sc. P.Eng. Secret Lab Technologies Ltd. grant.likely@secretlab.ca (403) 399-0195 ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: PPC beginner questions 2006-08-21 15:38 ` Grant Likely @ 2006-08-21 16:07 ` Wade Maxfield 2006-08-21 16:24 ` Grant Likely 0 siblings, 1 reply; 6+ messages in thread From: Wade Maxfield @ 2006-08-21 16:07 UTC (permalink / raw) To: Grant Likely; +Cc: linuxppc-embedded list [-- Attachment #1: Type: text/plain, Size: 2008 bytes --] OK. I'm breaking my promise. :) A couple more questions. On 8/21/06, Grant Likely <grant.likely@secretlab.ca> wrote: > > On 8/21/06, Wade Maxfield <wmaxfield@gmail.com> wrote: > > Hi Grant, > > > > Thanks! > > > > in* > > out* > > > > I'm assuming inb() outb(), inw() outw()?? I've been googling and have > > come up short with info that makes sense. It is almost all x86 centric. > > in_8, in_be16, in_be32, out_8, out_be16, out_be32 for big-endian > device registers > in_8, in_le16, in_le32, out_8, out_le16, out_le32 for little endian > device registers -->Interesting. Do these functions do 'eieio' (Email, Internet, Electronic Information Officer functions (southpark cartoon), err, or Enforce In-Order Execution of Input/Output) for me, or do I have to do that? I'm still confused as to that Old MacDonald function. > > > We will not be porting these drivers, this is a captive box internal > use > > only, limited run (200 units or so), 10 to 20 year lifespan once it hits > the > > field. > > > > So, the virtual address I get back can be used directly. Can I cast > to > > short * and long * and char *? > > heh, yes you can; but if your writing new code why not use good > practice from the start? :) --> Ok, you win. How about ioread8() or inb() also? Are they not coded in PPC correctly? Or is the in_8() more modern? > > > I apologize for the basic questions, but I expect this will be a > final > > question for quite some time. > > No worries; ask away! --> is ioremap() equivalent to ioremap_nocache() on the PPC 405? THANKS AGAIN!!!! wade :) Cheers, > g. > > > BTW, when on the mailing list, please use "reply to all" and put your > comments below what you're commenting on. This keeps the thread on > the mailing list for others to see, and it makes it blatentely obvious > what you're commenting on. (just general list-etiquette) > > -- > Grant Likely, B.Sc. P.Eng. > Secret Lab Technologies Ltd. > grant.likely@secretlab.ca > (403) 399-0195 > [-- Attachment #2: Type: text/html, Size: 3184 bytes --] ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: PPC beginner questions 2006-08-21 16:07 ` Wade Maxfield @ 2006-08-21 16:24 ` Grant Likely 0 siblings, 0 replies; 6+ messages in thread From: Grant Likely @ 2006-08-21 16:24 UTC (permalink / raw) To: Wade Maxfield; +Cc: linuxppc-embedded list On 8/21/06, Wade Maxfield <wmaxfield@gmail.com> wrote: > On 8/21/06, Grant Likely <grant.likely@secretlab.ca > wrote: > > On 8/21/06, Wade Maxfield <wmaxfield@gmail.com > wrote: > > > I'm assuming inb() outb(), inw() outw()?? I've been googling and have > > > come up short with info that makes sense. It is almost all x86 centric. > > > > in_8, in_be16, in_be32, out_8, out_be16, out_be32 for big-endian > > device registers > > in_8, in_le16, in_le32, out_8, out_le16, out_le32 for little endian > > device registers > > > -->Interesting. Do these functions do 'eieio' (Email, Internet, Electronic > Information Officer functions (southpark cartoon), err, or Enforce In-Order > Execution of Input/Output) for me, or do I have to do that? I'm still > confused as to that Old MacDonald function. The in functions do isync The out functions do eieio > > > > heh, yes you can; but if your writing new code why not use good > > practice from the start? :) > > > --> Ok, you win. How about ioread8() or inb() also? Are they not coded in > PPC correctly? Or is the in_8() more modern? read include/asm/io.h. All the IO routines are defined there. read[bwl] and write[bwl] are just macros to in_* out_*, as are inb, outb, etc. Cheers, g. -- Grant Likely, B.Sc. P.Eng. Secret Lab Technologies Ltd. grant.likely@secretlab.ca (403) 399-0195 ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: PPC beginner questions 2006-08-21 13:51 PPC beginner questions Wade Maxfield 2006-08-21 14:14 ` Grant Likely @ 2006-08-22 8:53 ` David H. Lynch Jr. 1 sibling, 0 replies; 6+ messages in thread From: David H. Lynch Jr. @ 2006-08-22 8:53 UTC (permalink / raw) To: Wade Maxfield; +Cc: ppc [-- Attachment #1: Type: text/plain, Size: 2994 bytes --] Wade Maxfield wrote: > > I'm new to the PPC and I have a few questions. I have written a > driver in the past for the X86 family, using i/o ports, but it was > kernel 2.0 and i/o ports are not mmu handled. > I've been looking through the archive and I am slowly growing more > confused. The PPC MMU is pretty simple compared to the x86. Basically the MMU unit is a peice of hardware that maps "virtual" addresses to "physical" addresses. Its use is enabled/disabled by two bits in the PPC Machine Status register - 1 for instructions, 1 for data. The MMU itself is basically a 64 entry lookup table. Virtual address X corresponds to physical address Y. When a request is made for an address that is not in the 64 entry MMU table things become more complex - an exception is generated and code inside Linux searches its tables to find the correct entry to stuff into the MMU. NORMALLY there is no correspondence between physical addresses and virtual ones. But it is possible (and might be useful for debugging) to stuff an entry where physical=virtual. If you look inside head_4xx.S for CONFIG_SERIAL_TEXT_DEBUG or something like that you should see how to do it. However manually stuffed entries in the MMU will eventually get blown away. I spent a week trying to trace a problem caused by that down. > > We are using Xilinx with PPC built in. > > The PPC has a memory management unit. All of the IP we've added is > mapped to physical addresses. > > 1. Can I access the memory the peripherasl are mapped to directly > within the driver without going through functions? > if NOT, then Do I use > 1. ioremap(), Once you have done the ioremap(), you can use the address returned exactly the way you would have used the physical address previously. > 2. request_mem_region(), > 3. request_region() > 4. something else? > > 2. Are there any gotcha's with the ppc 405 that Xilinx uses that I > should know about? Are you doing board bringup ? If you are not bringing up a new board - then the big gotcha's should already be covered. If you are doing board bringup - I would recommend following the existing xilinx packages closely. > > > thanks, > wade > > > ------------------------------------------------------------------------ > > _______________________________________________ > Linuxppc-embedded mailing list > Linuxppc-embedded@ozlabs.org > https://ozlabs.org/mailman/listinfo/linuxppc-embedded -- Dave Lynch DLA Systems Software Development: Embedded Linux 717.627.3770 dhlii@dlasys.net http://www.dlasys.net fax: 1.253.369.9244 Cell: 1.717.587.7774 Over 25 years' experience in platforms, languages, and technologies too numerous to list. "Any intelligent fool can make things bigger and more complex... It takes a touch of genius - and a lot of courage to move in the opposite direction." Albert Einstein [-- Attachment #2: Type: text/html, Size: 4574 bytes --] ^ permalink raw reply [flat|nested] 6+ messages in thread
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2006-08-21 13:51 PPC beginner questions Wade Maxfield
2006-08-21 14:14 ` Grant Likely
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2006-08-21 15:38 ` Grant Likely
2006-08-21 16:07 ` Wade Maxfield
2006-08-21 16:24 ` Grant Likely
2006-08-22 8:53 ` David H. Lynch Jr.
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