powerpc: Add Initiate Coprocessor Store Word (icswx) support

Icswx is a PowerPC instruction to send data to a co-processor. On Book-S
processors the LPAR_ID and process ID (PID) of the owning process are
registered in the window context of the co-processor at initialization
time. When the icswx instruction is executed the L2 generates a cop-reg
transaction on PowerBus. The transaction has no address and the
processor does not perform an MMU access to authenticate the transaction.
The co-processor compares the LPAR_ID and the PID included in the
transaction and the LPAR_ID and PID held in the window context to
determine if the process is authorized to generate the transaction.

The OS needs to assign a 16-bit PID for the process. This cop-PID needs
to be updated during context switch. The cop-PID needs to be destroyed
when the context is destroyed.

Signed-off-by: Sonny Rao <sonnyrao@linux.vnet.ibm.com>
Signed-off-by: Tseng-Hui (Frank) Lin <thlin@linux.vnet.ibm.com>
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

1 files changed, 6 insertions, 0 deletions

diff --git a/arch/powerpc/include/asm/mmu-hash64.h b/arch/powerpc/include/asm/mmu-hash64.h
index ae7b3efec8e5..d865bd909c7d 100644
--- a/arch/powerpc/include/asm/mmu-hash64.h
+++ b/arch/powerpc/include/asm/mmu-hash64.h
@@ -408,6 +408,7 @@ static inline void subpage_prot_init_new_context(struct mm_struct *mm) { }
 #endif /* CONFIG_PPC_SUBPAGE_PROT */
 
 typedef unsigned long mm_context_id_t;
+struct spinlock;
 
 typedef struct {
         mm_context_id_t id;
@@ -423,6 +424,11 @@ typedef struct {
 #ifdef CONFIG_PPC_SUBPAGE_PROT
         struct subpage_prot_table spt;
 #endif /* CONFIG_PPC_SUBPAGE_PROT */
+#ifdef CONFIG_PPC_ICSWX
+        struct spinlock *cop_lockp; /* guard acop and cop_pid */
+        unsigned long acop;     /* mask of enabled coprocessor types */
+        unsigned int cop_pid;   /* pid value used with coprocessors */
+#endif /* CONFIG_PPC_ICSWX */
 } mm_context_t;