* Re: Add skeleton "generic IO mapping" infrastructure. [not found] <200409132206.i8DM6dSC030620@hera.kernel.org> @ 2004-09-14 8:55 ` David Woodhouse 2004-09-14 14:30 ` Jeff Garzik 0 siblings, 1 reply; 4+ messages in thread From: David Woodhouse @ 2004-09-14 8:55 UTC (permalink / raw) To: Linux Kernel Mailing List; +Cc: jgarzik On Mon, 2004-09-13 at 18:32 +0000, Linux Kernel Mailing List wrote: > ChangeSet 1.1869, 2004/09/13 11:32:00-07:00, torvalds@ppc970.osdl.org > > Add skeleton "generic IO mapping" infrastructure. > > Jeff wants to use this to clean up SATA and some network drivers. > + * Read/write from/to an (offsettable) iomem cookie. It might be a PIO > + * access or a MMIO access, these functions don't care. The info is > + * encoded in the hardware mapping set up by the mapping functions > + * (or the cookie itself, depending on implementation and hw). > + * > + * The generic routines don't assume any hardware mappings, and just > + * encode the PIO/MMIO as part of the cookie. They coldly assume that > + * the MMIO IO mappings are not in the low address range. > + * > + * Architectures for which this is not true can't use this generic > + * implementation and should do their own copy. > + * > + * We encode the physical PIO addresses (0-0xffff) into the > + * pointer by offsetting them with a constant (0x10000) and > + * assuming that all the low addresses are always PIO. That means > + * we can do some sanity checks on the low bits, and don't > + * need to just take things for granted. > + */ > +#define PIO_OFFSET 0x10000 > +#define PIO_MASK 0x0ffff > +#define PIO_RESERVED 0x40000 > +#define IO_COND(addr, is_pio, is_mmio) do { \ > + unsigned long port = (unsigned long __force)addr; \ > + if (port < PIO_RESERVED) { \ > + VERIFY_PIO(port); \ > + port &= PIO_MASK; \ > + is_pio; \ > + } else { \ > + is_mmio; \ > + } \ > +} while (0) Argh! Please no. You can't infer the IO space from the address. Provide a cookie containing {space, address} instead -- or indeed {bus, address}. Let some architectures optimise that by ignoring the bus and working it out from the address if you must, but don't put that in the generic version. -- dwmw2 ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: Add skeleton "generic IO mapping" infrastructure. 2004-09-14 8:55 ` Add skeleton "generic IO mapping" infrastructure David Woodhouse @ 2004-09-14 14:30 ` Jeff Garzik 2004-09-14 14:33 ` David Woodhouse 0 siblings, 1 reply; 4+ messages in thread From: Jeff Garzik @ 2004-09-14 14:30 UTC (permalink / raw) To: David Woodhouse; +Cc: Linux Kernel Mailing List David Woodhouse wrote: > On Mon, 2004-09-13 at 18:32 +0000, Linux Kernel Mailing List wrote: > >>ChangeSet 1.1869, 2004/09/13 11:32:00-07:00, torvalds@ppc970.osdl.org >> >> Add skeleton "generic IO mapping" infrastructure. >> >> Jeff wants to use this to clean up SATA and some network drivers. > > > >>+ * Read/write from/to an (offsettable) iomem cookie. It might be a PIO >>+ * access or a MMIO access, these functions don't care. The info is >>+ * encoded in the hardware mapping set up by the mapping functions >>+ * (or the cookie itself, depending on implementation and hw). >>+ * >>+ * The generic routines don't assume any hardware mappings, and just >>+ * encode the PIO/MMIO as part of the cookie. They coldly assume that >>+ * the MMIO IO mappings are not in the low address range. >>+ * >>+ * Architectures for which this is not true can't use this generic >>+ * implementation and should do their own copy. >>+ * >>+ * We encode the physical PIO addresses (0-0xffff) into the >>+ * pointer by offsetting them with a constant (0x10000) and >>+ * assuming that all the low addresses are always PIO. That means >>+ * we can do some sanity checks on the low bits, and don't >>+ * need to just take things for granted. >>+ */ >>+#define PIO_OFFSET 0x10000 >>+#define PIO_MASK 0x0ffff >>+#define PIO_RESERVED 0x40000 > > >>+#define IO_COND(addr, is_pio, is_mmio) do { \ >>+ unsigned long port = (unsigned long __force)addr; \ >>+ if (port < PIO_RESERVED) { \ >>+ VERIFY_PIO(port); \ >>+ port &= PIO_MASK; \ >>+ is_pio; \ >>+ } else { \ >>+ is_mmio; \ >>+ } \ >>+} while (0) > > > Argh! Please no. You can't infer the IO space from the address. Provide > a cookie containing {space, address} instead -- or indeed {bus, > address}. Let some architectures optimise that by ignoring the bus and > working it out from the address if you must, but don't put that in the > generic version. Override it in your arch if you don't like the generic version ;-) Jeff ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: Add skeleton "generic IO mapping" infrastructure. 2004-09-14 14:30 ` Jeff Garzik @ 2004-09-14 14:33 ` David Woodhouse 2004-09-14 15:06 ` Jeff Garzik 0 siblings, 1 reply; 4+ messages in thread From: David Woodhouse @ 2004-09-14 14:33 UTC (permalink / raw) To: Jeff Garzik; +Cc: Linux Kernel Mailing List On Tue, 2004-09-14 at 10:30 -0400, Jeff Garzik wrote: > Override it in your arch if you don't like the generic version ;-) If you must... but make it take a cookie with enough space to give the required information -- not just an unsigned long. -- dwmw2 ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: Add skeleton "generic IO mapping" infrastructure. 2004-09-14 14:33 ` David Woodhouse @ 2004-09-14 15:06 ` Jeff Garzik 0 siblings, 0 replies; 4+ messages in thread From: Jeff Garzik @ 2004-09-14 15:06 UTC (permalink / raw) To: David Woodhouse; +Cc: Linux Kernel Mailing List David Woodhouse wrote: > On Tue, 2004-09-14 at 10:30 -0400, Jeff Garzik wrote: > >>Override it in your arch if you don't like the generic version ;-) > > > If you must... but make it take a cookie with enough space to give the > required information -- not just an unsigned long. If you have (device, address) you should have all you need... Jeff ^ permalink raw reply [flat|nested] 4+ messages in thread
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2004-09-14 8:55 ` Add skeleton "generic IO mapping" infrastructure David Woodhouse
2004-09-14 14:30 ` Jeff Garzik
2004-09-14 14:33 ` David Woodhouse
2004-09-14 15:06 ` Jeff Garzik
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