[PATCH 01/16] ARM: scu: Provide support for parsing SCU device node to enable SCU

[Pankaj Dubey]

Many platforms are duplicating code for enabling SCU, lets add
common code to enable SCU by parsing SCU device node so the duplication
in each platform can be avoided.

CC: Krzysztof Kozlowski <krzk@xxxxxxxxxx>
CC: Jisheng Zhang <jszhang@xxxxxxxxxxx>
CC: Russell King <linux@xxxxxxxxxxxxxxx>
CC: Dinh Nguyen <dinguyen@xxxxxxxxxxxxxxxxxxxxx>
CC: Patrice Chotard <patrice.chotard@xxxxxx>
CC: Linus Walleij <linus.walleij@xxxxxxxxxx>
CC: Liviu Dudau <liviu.dudau@xxxxxxx>
CC: Ray Jui <rjui@xxxxxxxxxxxx>
CC: Stephen Warren <swarren@xxxxxxxxxxxxx>
CC: Heiko Stuebner <heiko@xxxxxxxxx>
CC: Shawn Guo <shawnguo@xxxxxxxxxx>
CC: Michal Simek <michal.simek@xxxxxxxxxx>
CC: Wei Xu <xuwei5@xxxxxxxxxxxxx>
CC: Andrew Lunn <andrew@xxxxxxx>
CC: Jun Nie <jun.nie@xxxxxxxxxx> 
Suggested-by: Arnd Bergmann <arnd@xxxxxxxx>
Signed-off-by: Pankaj Dubey <pankaj.dubey@xxxxxxxxxxx>
---
 arch/arm/include/asm/smp_scu.h |  4 +++
 arch/arm/kernel/smp_scu.c      | 56 ++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 60 insertions(+)

diff --git a/arch/arm/include/asm/smp_scu.h b/arch/arm/include/asm/smp_scu.h
index bfe163c..fdeec07 100644
--- a/arch/arm/include/asm/smp_scu.h
+++ b/arch/arm/include/asm/smp_scu.h
@@ -39,8 +39,12 @@ static inline int scu_power_mode(void __iomem *scu_base, unsigned int mode)
 
 #if defined(CONFIG_SMP) && defined(CONFIG_HAVE_ARM_SCU)
 void scu_enable(void __iomem *scu_base);
+void __iomem *of_scu_get_base(void);
+int of_scu_enable(void);
 #else
 static inline void scu_enable(void __iomem *scu_base) {}
+static inline void __iomem *of_scu_get_base(void) {return NULL; }
+static inline int of_scu_enable(void) {return 0; }
 #endif
 
 #endif
diff --git a/arch/arm/kernel/smp_scu.c b/arch/arm/kernel/smp_scu.c
index 72f9241..d0ac3ed 100644
--- a/arch/arm/kernel/smp_scu.c
+++ b/arch/arm/kernel/smp_scu.c
@@ -10,6 +10,7 @@
  */
 #include <linux/init.h>
 #include <linux/io.h>
+#include <linux/of_address.h>
 
 #include <asm/smp_plat.h>
 #include <asm/smp_scu.h>
@@ -70,6 +71,61 @@ void scu_enable(void __iomem *scu_base)
 	 */
 	flush_cache_all();
 }
+
+static const struct of_device_id scu_match[] = {
+	{ .compatible = "arm,cortex-a9-scu", },
+	{ .compatible = "arm,cortex-a5-scu", },
+	{ }
+};
+
+/*
+ * Helper API to get SCU base address
+ * In case platform DT do not have SCU node, or iomap fails
+ * this call will fallback and will try to map via call to
+ * scu_a9_get_base.
+ * This will return ownership of scu_base to the caller
+ */
+void __iomem *of_scu_get_base(void)
+{
+	unsigned long base = 0;
+	struct device_node *np;
+	void __iomem *scu_base;
+
+	np = of_find_matching_node(NULL, scu_match);
+	scu_base = of_iomap(np, 0);
+	of_node_put(np);
+	if (!scu_base) {
+		pr_err("%s failed to map scu_base via DT\n", __func__);
+		if (scu_a9_has_base()) {
+			base = scu_a9_get_base();
+			scu_base = ioremap(base, SZ_4K);
+		}
+		if (!scu_base) {
+			pr_err("%s failed to map scu_base\n", __func__);
+			return IOMEM_ERR_PTR(-ENOMEM);
+		}
+	}
+	return scu_base;
+}
+
+/*
+ * Enable SCU via mapping scu_base DT
+ * If scu_base mapped successfully scu will be enabled and in case of
+ * failure if will return non-zero error code
+ */
+int of_scu_enable(void)
+{
+	void __iomem *scu_base;
+
+	scu_base = of_scu_get_base();
+	if (!IS_ERR(scu_base)) {
+		scu_enable(scu_base);
+		iounmap(scu_base);
+		return 0;
+	}
+	return PTR_ERR(scu_base);
+}
+
 #endif
 
 /*
-- 
2.7.4