[SPARC64]: Add hypervisor API negotiation and fix console bugs.

Hypervisor interfaces need to be negotiated in order to use
some API calls reliably.  So add a small set of interfaces
to request API versions and query current settings.

This allows us to fix some bugs in the hypervisor console:

1) If we can negotiate API group CORE of at least major 1
   minor 1 we can use con_read and con_write which can improve
   console performance quite a bit.

2) When we do a console write request, we should hold the
   spinlock around the whole request, not a byte at a time.
   What would happen is that it's easy for output from
   different cpus to get mixed with each other.

3) Use consistent udelay() based polling, udelay(1) each
   loop with a limit of 1000 polls to handle stuck hypervisor
   console.

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 94 insertions, 0 deletions

diff --git a/arch/sparc64/kernel/entry.S b/arch/sparc64/kernel/entry.S
index c15a3edcb826..732b77cb71f8 100644
--- a/arch/sparc64/kernel/entry.S
+++ b/arch/sparc64/kernel/entry.S
@@ -1843,3 +1843,97 @@ sun4v_cpu_state:
         mov     %o1, %o0
 1:      retl
          nop
+
+        /* %o0: API group number
+         * %o1: pointer to unsigned long major number storage
+         * %o2: pointer to unsigned long minor number storage
+         *
+         * returns %o0: status
+         */
+        .globl  sun4v_get_version
+sun4v_get_version:
+        mov     HV_CORE_GET_VER, %o5
+        mov     %o1, %o3
+        mov     %o2, %o4
+        ta      HV_CORE_TRAP
+        stx     %o1, [%o3]
+        retl
+         stx    %o2, [%o4]
+
+        /* %o0: API group number
+         * %o1: desired major number
+         * %o2: desired minor number
+         * %o3: pointer to unsigned long actual minor number storage
+         *
+         * returns %o0: status
+         */
+        .globl  sun4v_set_version
+sun4v_set_version:
+        mov     HV_CORE_SET_VER, %o5
+        mov     %o3, %o4
+        ta      HV_CORE_TRAP
+        retl
+         stx    %o1, [%o4]
+
+        /* %o0: pointer to unsigned long status
+         *
+         * returns %o0: signed character
+         */
+        .globl  sun4v_con_getchar
+sun4v_con_getchar:
+        mov     %o0, %o4
+        mov     HV_FAST_CONS_GETCHAR, %o5
+        clr     %o0
+        clr     %o1
+        ta      HV_FAST_TRAP
+        stx     %o0, [%o4]
+        retl
+         sra    %o1, 0, %o0
+
+        /* %o0: signed long character
+         *
+         * returns %o0: status
+         */
+        .globl  sun4v_con_putchar
+sun4v_con_putchar:
+        mov     HV_FAST_CONS_PUTCHAR, %o5
+        ta      HV_FAST_TRAP
+        retl
+         sra    %o0, 0, %o0
+
+        /* %o0: buffer real address
+         * %o1: buffer size
+         * %o2: pointer to unsigned long bytes_read
+         *
+         * returns %o0: status
+         */
+        .globl  sun4v_con_read
+sun4v_con_read:
+        mov     %o2, %o4
+        mov     HV_FAST_CONS_READ, %o5
+        ta      HV_FAST_TRAP
+        brnz    %o0, 1f
+         cmp    %o1, -1         /* break */
+        be,a,pn %icc, 1f
+         mov    %o1, %o0
+        cmp     %o1, -2         /* hup */
+        be,a,pn %icc, 1f
+         mov    %o1, %o0
+        stx     %o1, [%o4]
+1:      retl
+         nop
+
+        /* %o0: buffer real address
+         * %o1: buffer size
+         * %o2: pointer to unsigned long bytes_written
+         *
+         * returns %o0: status
+         */
+        .globl  sun4v_con_write
+sun4v_con_write:
+        mov     %o2, %o4
+        mov     HV_FAST_CONS_WRITE, %o5
+        ta      HV_FAST_TRAP
+        stx     %o1, [%o4]
+        retl
+         nop