[RFC 1/6] powerpc/hv-24x7: Add rtas call in hv-24x7 driver to get processor details

[Kajol Jain <kjain@linux.ibm.com>]

For hv_24x7 socket/chip level events, specific chip-id to which
the data requested should be added as part of pmu events.
But number of chips/socket in the system details are not exposed.

Patch implements read_sys_info_pseries() to get system
parameter values like number of sockets and chips per socket.
Rtas_call with token "PROCESSOR_MODULE_INFO"
is used to get these values.

Patch also make these parameters default to 1.

Signed-off-by: Kajol Jain <kjain@linux.ibm.com>
---
 arch/powerpc/perf/hv-24x7.c              | 68 ++++++++++++++++++++++++
 arch/powerpc/platforms/pseries/pseries.h |  3 ++
 2 files changed, 71 insertions(+)

diff --git a/arch/powerpc/perf/hv-24x7.c b/arch/powerpc/perf/hv-24x7.c
index 573e0b309c0c..64d9fc526d68 100644
--- a/arch/powerpc/perf/hv-24x7.c
+++ b/arch/powerpc/perf/hv-24x7.c
@@ -19,6 +19,8 @@
 #include <asm/hvcall.h>
 #include <asm/io.h>
 #include <linux/byteorder/generic.h>
+#include <asm/rtas.h>
+#include <../../platforms/pseries/pseries.h>
 
 #include "hv-24x7.h"
 #include "hv-24x7-catalog.h"
@@ -57,6 +59,68 @@ static bool is_physical_domain(unsigned domain)
 	}
 }
 
+#ifdef CONFIG_PPC_RTAS
+#define PROCESSOR_MODULE_INFO   43
+#define PROCESSOR_MAX_LENGTH	(8 * 1024)
+
+static int strbe16toh(const char *buf, int offset)
+{
+	return (buf[offset] << 8) + buf[offset + 1];
+}
+
+static u32		physsockets;	/* Physical sockets */
+static u32		physchips;	/* Physical chips */
+
+/* Function read_sys_info_pseries() make a rtas_call which require
+ * data buffer of size 8K. As standard 'rtas_data_buf' is of size
+ * 4K, we are adding new local buffer 'rtas_local_data_buf'.
+ */
+char rtas_local_data_buf[PROCESSOR_MAX_LENGTH] __cacheline_aligned;
+
+/*
+ * read_sys_info_pseries()
+ * Retrieve the number of sockets and chips per socket details
+ * through the get-system-parameter rtas call.
+ */
+void read_sys_info_pseries(void)
+{
+	int call_status, len, ntypes;
+
+	/*
+	 * Making system parameter: chips and sockets default to 1.
+	 */
+	physsockets = 1;
+	physchips = 1;
+	memset(rtas_local_data_buf, 0, PROCESSOR_MAX_LENGTH);
+	spin_lock(&rtas_data_buf_lock);
+
+	call_status = rtas_call(rtas_token("ibm,get-system-parameter"), 3, 1,
+				NULL,
+				PROCESSOR_MODULE_INFO,
+				__pa(rtas_local_data_buf),
+				PROCESSOR_MAX_LENGTH);
+
+	spin_unlock(&rtas_data_buf_lock);
+
+	if (call_status != 0) {
+		pr_info("%s %s Error calling get-system-parameter (0x%x)\n",
+			__FILE__, __func__, call_status);
+	} else {
+		rtas_local_data_buf[PROCESSOR_MAX_LENGTH - 1] = '\0';
+		len = strbe16toh(rtas_local_data_buf, 0);
+		if (len < 6)
+			return;
+
+		ntypes = strbe16toh(rtas_local_data_buf, 2);
+
+		if (!ntypes)
+			return;
+		physsockets = strbe16toh(rtas_local_data_buf, 4);
+		physchips = strbe16toh(rtas_local_data_buf, 6);
+	}
+}
+#endif /* CONFIG_PPC_RTAS */
+
 /* Domains for which more than one result element are returned for each event. */
 static bool domain_needs_aggregation(unsigned int domain)
 {
@@ -1615,6 +1679,10 @@ static int hv_24x7_init(void)
 	if (r)
 		return r;
 
+#ifdef CONFIG_PPC_RTAS
+	read_sys_info_pseries();
+#endif
+
 	return 0;
 }
 
diff --git a/arch/powerpc/platforms/pseries/pseries.h b/arch/powerpc/platforms/pseries/pseries.h
index 13fa370a87e4..1727559ce304 100644
--- a/arch/powerpc/platforms/pseries/pseries.h
+++ b/arch/powerpc/platforms/pseries/pseries.h
@@ -19,6 +19,9 @@ extern void request_event_sources_irqs(struct device_node *np,
 struct pt_regs;
 
 extern int pSeries_system_reset_exception(struct pt_regs *regs);
+#ifdef CONFIG_PPC_RTAS
+extern void read_sys_info_pseries(void);
+#endif
 extern int pSeries_machine_check_exception(struct pt_regs *regs);
 extern long pseries_machine_check_realmode(struct pt_regs *regs);
 
-- 
2.18.1