[PATCH RFC 8/9] powerpc/pseries: Enable hvpipe with ibm,set-system-parameter RTAS

[Haren Myneni <haren@linux.ibm.com>]

The partition uses “Hypervisor Pipe OS Enablement Notification”
system parameter token (value = 64) to enable / disable hvpipe in
the hypervisor. Once hvpipe is enabled, the hypervisor notifies
OS if the payload is pending for that partition from any source.
This system parameter token takes 1 byte length of data with
1 = Enable and 0 = Disable.

Enable hvpipe in the hypervisor with ibm,set-system-parameter
RTAS after registering hvpipe event source interrupt.

Signed-off-by: Haren Myneni <haren@linux.ibm.com>
---
 arch/powerpc/include/asm/papr-sysparm.h      |  1 +
 arch/powerpc/platforms/pseries/papr-hvpipe.c | 29 +++++++++++++++++++-
 2 files changed, 29 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/include/asm/papr-sysparm.h b/arch/powerpc/include/asm/papr-sysparm.h
index c3cd5b131033..11430e5a7224 100644
--- a/arch/powerpc/include/asm/papr-sysparm.h
+++ b/arch/powerpc/include/asm/papr-sysparm.h
@@ -21,6 +21,7 @@ typedef struct {
 #define PAPR_SYSPARM_COOP_MEM_OVERCOMMIT_ATTRS     mk_papr_sysparm(44)
 #define PAPR_SYSPARM_TLB_BLOCK_INVALIDATE_ATTRS    mk_papr_sysparm(50)
 #define PAPR_SYSPARM_LPAR_NAME                     mk_papr_sysparm(55)
+#define PAPR_SYS_PARAM_HVPIPE_ENABLE               mk_papr_sysparm(64)
 
 /**
  * struct papr_sysparm_buf - RTAS work area layout for system parameter functions.
diff --git a/arch/powerpc/platforms/pseries/papr-hvpipe.c b/arch/powerpc/platforms/pseries/papr-hvpipe.c
index ebccd6a70ab6..b103dde7d584 100644
--- a/arch/powerpc/platforms/pseries/papr-hvpipe.c
+++ b/arch/powerpc/platforms/pseries/papr-hvpipe.c
@@ -15,6 +15,7 @@
 #include <asm/machdep.h>
 #include <asm/rtas.h>
 #include <asm/rtas-work-area.h>
+#include <asm/papr-sysparm.h>
 #include <uapi/asm/papr-hvpipe.h>
 #include "pseries.h"
 #include "papr-hvpipe.h"
@@ -639,6 +640,32 @@ static irqreturn_t hvpipe_event_interrupt(int irq, void *dev_id)
 	return IRQ_HANDLED;
 }
 
+/*
+ * Enable hvpipe by system parameter set with parameter
+ * token = 64 and with 1 byte buffer data:
+ * 0 = hvpipe not in use/disabled
+ * 1 = hvpipe in use/enabled
+ */
+static int set_hvpipe_sys_param(u8 val)
+{
+	struct papr_sysparm_buf *buf;
+	int ret;
+
+	buf = papr_sysparm_buf_alloc();
+	if (!buf)
+		return -ENOMEM;
+
+	buf->len = cpu_to_be16(1);
+	buf->val[0] = val;
+	ret = papr_sysparm_set(PAPR_SYS_PARAM_HVPIPE_ENABLE, buf);
+	if (!ret)
+		pr_err("Can not enable hvpipe %d\n", ret);
+
+	papr_sysparm_buf_free(buf);
+
+	return ret;
+}
+
 static int __init enable_hvpipe_IRQ(void)
 {
 	struct device_node *np;
@@ -695,7 +722,7 @@ static int __init papr_hvpipe_init(void)
 		goto out;
 	}
 
-	if (!enable_hvpipe_IRQ()) {
+	if (!enable_hvpipe_IRQ() && !set_hvpipe_sys_param(1)) {
 		ret = misc_register(&papr_hvpipe_dev);
 		if (!ret) {
 			pr_info("hvpipe feature is enabled\n");
-- 
2.43.5