powerpc/pseries: Export data from new hcall H_EM_GET_PARMS

Add support for H_EM_GET_PARMS hcall that will return data
related to power modes from the platform.  Export the data
directly to user space for administrative tools to interpret
and use.

cat /proc/powerpc/lparcfg will export power mode data
Signed-off-by: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/include/asm/hvcall.h

@@ -228,6 +228,7 @@
 #define H_JOIN			0x298
 #define H_VASI_STATE            0x2A4
 #define H_ENABLE_CRQ		0x2B0
+#define H_GET_EM_PARMS		0x2B8
 #define H_SET_MPP		0x2D0
 #define H_GET_MPP		0x2D4
 #define MAX_HCALL_OPCODE	H_GET_MPP

arch/powerpc/kernel/lparcfg.c

@@ -38,7 +38,7 @@
 #include <asm/vio.h>
 #include <asm/mmu.h>
 
-#define MODULE_VERS "1.8"
+#define MODULE_VERS "1.9"
 #define MODULE_NAME "lparcfg"
 
 /* #define LPARCFG_DEBUG */
@@ -487,6 +487,14 @@ static void splpar_dispatch_data(struct seq_file *m)
 	seq_printf(m, "dispatch_dispersions=%lu\n", dispatch_dispersions);
 }
 
+static void parse_em_data(struct seq_file *m)
+{
+	unsigned long retbuf[PLPAR_HCALL_BUFSIZE];
+
+	if (plpar_hcall(H_GET_EM_PARMS, retbuf) == H_SUCCESS)
+		seq_printf(m, "power_mode_data=%016lx\n", retbuf[0]);
+}
+
 static int pseries_lparcfg_data(struct seq_file *m, void *v)
 {
 	int partition_potential_processors;
@@ -541,6 +549,8 @@ static int pseries_lparcfg_data(struct seq_file *m, void *v)
 
 	seq_printf(m, "slb_size=%d\n", mmu_slb_size);
 
+	parse_em_data(m);
+
 	return 0;
 }