[Xen-devel] [PATCH v2 3/6] arm: parse PSCI node from the host device-tree

[Andre Przywara <andre.przywara@xxxxxxxxxx>]

The availability of a PSCI handler is advertised in the DTB.
Find and parse the node (described in the Linux device-tree binding)
and save the function number for bringing up a CPU for later usage.
We do some sanity checks, especially we deny using HVC as a calling
method, as it does not make much sense currently under Xen.

Signed-off-by: Andre Przywara <andre.przywara@xxxxxxxxxx>
---
 xen/arch/arm/Makefile      |  1 +
 xen/arch/arm/psci.c        | 64 ++++++++++++++++++++++++++++++++++++++++++++++
 xen/arch/arm/smpboot.c     |  7 +++++
 xen/include/asm-arm/psci.h |  6 +++++
 4 files changed, 78 insertions(+)
 create mode 100644 xen/arch/arm/psci.c

diff --git a/xen/arch/arm/Makefile b/xen/arch/arm/Makefile
index 11cf663..d70f6d5 100644
--- a/xen/arch/arm/Makefile
+++ b/xen/arch/arm/Makefile
@@ -5,6 +5,7 @@ subdir-y += platforms
 obj-$(EARLY_PRINTK) += early_printk.o
 obj-y += cpu.o
 obj-y += domain.o
+obj-y += psci.o
 obj-y += vpsci.o
 obj-y += domctl.o
 obj-y += sysctl.o
diff --git a/xen/arch/arm/psci.c b/xen/arch/arm/psci.c
new file mode 100644
index 0000000..9ff06cd
--- /dev/null
+++ b/xen/arch/arm/psci.c
@@ -0,0 +1,64 @@
+/*
+ * xen/arch/arm/psci.c
+ *
+ * PSCI host support
+ *
+ * Andre Przywara <andre.przywara@xxxxxxxxxx>
+ * Copyright (c) 2013 Linaro Limited.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+
+#include <xen/types.h>
+#include <xen/mm.h>
+#include <xen/smp.h>
+#include <asm/psci.h>
+
+int psci_available;
+
+static uint32_t psci_cpu_on_nr;
+
+int __init psci_init(void)
+{
+    struct dt_device_node *psci;
+    int ret;
+    const char *prop_str;
+
+    psci = dt_find_compatible_node(NULL, NULL, "arm,psci");
+    if ( !psci )
+        return -ENODEV;
+
+    ret = dt_property_read_string(psci, "method", &prop_str);
+    if ( ret )
+    {
+        printk("/psci node does not provide a method (%d)\n", ret);
+        return -EINVAL;
+    }
+
+    /* Since Xen runs in HYP all of the time, it does not make sense to
+     * let it call into HYP for PSCI handling, since the handler won't
+     * just be there. So bail out with an error if "smc" is not used.
+     */
+    if ( strcmp(prop_str, "smc") )
+    {
+        printk("/psci method must be smc, but is: \"%s\"\n", prop_str);
+        return -EINVAL;
+    }
+
+    if ( !dt_property_read_u32(psci, "cpu_on", &psci_cpu_on_nr) )
+    {
+        printk("/psci node is missing the \"cpu_on\" property\n");
+        return -ENOENT;
+    }
+
+    return 0;
+}
diff --git a/xen/arch/arm/smpboot.c b/xen/arch/arm/smpboot.c
index 52cef30..3a9be90 100644
--- a/xen/arch/arm/smpboot.c
+++ b/xen/arch/arm/smpboot.c
@@ -30,6 +30,7 @@
 #include <xen/irq.h>
 #include <xen/console.h>
 #include <asm/gic.h>
+#include <asm/psci.h>
 
 cpumask_t cpu_online_map;
 cpumask_t cpu_present_map;
@@ -105,6 +106,12 @@ void __init smp_init_cpus(void)
     bool_t bootcpu_valid = 0;
     int rc;
 
+    if ( psci_init() == 0 )
+    {
+        printk(XENLOG_INFO "Using PSCI for SMP bringup\n");
+        psci_available = 1;
+    }
+
     if ( (rc = arch_smp_init()) < 0 )
     {
         printk(XENLOG_WARNING "SMP init failed (%d)\n"
diff --git a/xen/include/asm-arm/psci.h b/xen/include/asm-arm/psci.h
index 67d4c35..2f37612 100644
--- a/xen/include/asm-arm/psci.h
+++ b/xen/include/asm-arm/psci.h
@@ -6,6 +6,12 @@
 #define PSCI_EINVAL  -2
 #define PSCI_DENIED  -3
 
+/* availability of PSCI on the host for SMP bringup */
+extern int psci_available;
+
+int psci_init(void);
+
+/* functions to handle guest PSCI requests */
 int do_psci_cpu_on(uint32_t vcpuid, register_t entry_point);
 int do_psci_cpu_off(uint32_t power_state);
 int do_psci_cpu_suspend(uint32_t power_state, register_t entry_point);
-- 
1.7.12.1


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