path: root/arch/s390/include/asm/clp.h
diff options
authorNiklas Schnelle <schnelle@linux.ibm.com>2020-07-13 14:12:49 +0200
committerVasily Gorbik <gor@linux.ibm.com>2020-09-14 10:30:07 +0200
commitb02002cc4c0f8a2340d07690f58cae0c04ba2325 (patch)
treebdafb59b1cc746044018cbfd15f4e164aa230cfb /arch/s390/include/asm/clp.h
parent4d4a3caaf36246520d61c17a9fd86ce3893f6595 (diff)
s390/pci: Implement ioremap_wc/prot() with MIO
With our current support for the new MIO PCI instructions, write combining/write back MMIO memory can be obtained via the pci_iomap_wc() and pci_iomap_wc_range() functions. This is achieved by using the write back address for a specific bar as provided in clp_store_query_pci_fn() These functions are however not widely used and instead drivers often rely on ioremap_wc() and ioremap_prot(), which on other platforms enable write combining using a PTE flag set through the pgrprot value. While we do not have a write combining flag in the low order flag bits of the PTE like x86_64 does, with MIO support, there is a write back bit in the physical address (bit 1 on z15) and thus also the PTE. Which bit is used to toggle write back and whether it is available at all, is however not fixed in the architecture. Instead we get this information from the CLP Store Logical Processor Characteristics for PCI command. When the write back bit is not provided we fall back to the existing behavior. Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com> Reviewed-by: Pierre Morel <pmorel@linux.ibm.com> Reviewed-by: Gerald Schaefer <gerald.schaefer@linux.ibm.com> Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Diffstat (limited to 'arch/s390/include/asm/clp.h')
1 files changed, 3 insertions, 0 deletions
diff --git a/arch/s390/include/asm/clp.h b/arch/s390/include/asm/clp.h
index 3925b0f085b7..10919eeb7533 100644
--- a/arch/s390/include/asm/clp.h
+++ b/arch/s390/include/asm/clp.h
@@ -5,6 +5,9 @@
/* CLP common request & response block size */
+/* Call Logical Processor - Command Code */
+#define CLP_SLPC 0x0001
#define CLP_LPS_BASE 0
#define CLP_LPS_PCI 2

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