s390: Remove ioremap_wt() and pgprot_writethrough()

It turns out that while s390 architecture calls its memory-I/O mapping
variants write-through and write-back the implementation of ioremap_wt()
and pgprot_writethrough() does not match Linux notion of ioremap_wt().

In particular Linux expects ioremap_wt() to be weaker still than
ioremap_wc(), allowing not just gathering and re-ordering but also reads
to be served from cache. Instead s390's implementation is equivalent to
normal ioremap() while its ioremap_wc() allows re-ordering.

Note that there are no known users of ioremap_wt() on s390 and the
resulting behavior is in line with asm-generic defining ioremap_wt() as
ioremap(), if undefined, so no breakage is expected.

As s390 does not have a mapping type matching the Linux notion of
ioremap_wt() and pgprot_writethrough(), simply drop them and rely on the
asm-generic fallbacks instead.

Fixes: b02002cc4c0f ("s390/pci: Implement ioremap_wc/prot() with MIO")
Fixes: b43b3fff042d ("s390: mm: convert to GENERIC_IOREMAP")
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

diff --git a/arch/s390/include/asm/io.h b/arch/s390/include/asm/io.h
index fc9933a743d692196c322f77538d35b9a826a8ee..251e0372ccbd0a63fb859ebe2540c78d2a42a47b 100644 (file)
--- a/arch/s390/include/asm/io.h
+++ b/arch/s390/include/asm/io.h
@@ -34,8 +34,6 @@ void unxlate_dev_mem_ptr(phys_addr_t phys, void *addr);
 
 #define ioremap_wc(addr, size)  \
        ioremap_prot((addr), (size), pgprot_val(pgprot_writecombine(PAGE_KERNEL)))
-#define ioremap_wt(addr, size)  \
-       ioremap_prot((addr), (size), pgprot_val(pgprot_writethrough(PAGE_KERNEL)))
 
 static inline void __iomem *ioport_map(unsigned long port, unsigned int nr)
 {

diff --git a/arch/s390/include/asm/pgtable.h b/arch/s390/include/asm/pgtable.h
index fb757f5e220b0ec2fb7d15299573941ee8c43a10..e9c2d81f11f83fa3b3483383d3e0e7c680c2856a 100644 (file)
--- a/arch/s390/include/asm/pgtable.h
+++ b/arch/s390/include/asm/pgtable.h
@@ -1403,9 +1403,6 @@ void gmap_pmdp_idte_global(struct mm_struct *mm, unsigned long vmaddr);
 #define pgprot_writecombine    pgprot_writecombine
 pgprot_t pgprot_writecombine(pgprot_t prot);
 
-#define pgprot_writethrough    pgprot_writethrough
-pgprot_t pgprot_writethrough(pgprot_t prot);
-
 #define PFN_PTE_SHIFT          PAGE_SHIFT
 
 /*

diff --git a/arch/s390/mm/pgtable.c b/arch/s390/mm/pgtable.c
index e20fd4c14562cd9f5893d66ad00b84df536d8726..fa66246c185131df905d0d4441550e1484562336 100644 (file)
--- a/arch/s390/mm/pgtable.c
+++ b/arch/s390/mm/pgtable.c
@@ -36,16 +36,6 @@ pgprot_t pgprot_writecombine(pgprot_t prot)
 }
 EXPORT_SYMBOL_GPL(pgprot_writecombine);
 
-pgprot_t pgprot_writethrough(pgprot_t prot)
-{
-       /*
-        * mio_wb_bit_mask may be set on a different CPU, but it is only set
-        * once at init and only read afterwards.
-        */
-       return __pgprot(pgprot_val(prot) & ~mio_wb_bit_mask);
-}
-EXPORT_SYMBOL_GPL(pgprot_writethrough);
-
 static inline void ptep_ipte_local(struct mm_struct *mm, unsigned long addr,
                                   pte_t *ptep, int nodat)
 {