[PATCH 2/2] ARM: zynq: Add support for Zynq-7000S devices

[Michal Simek]

Patch adds detection of Zynq-7000 base silicon configuration,
namely Dual or Single CPU. Device trees attempting to enable DUAL CORE
behavior on SINGLE CPU Zynq-7000S devices are prevented from corrupting
system behavior.

Detection of Dual or Single CPU is done via eFuses.

Signed-off-by: Michal Simek <michal.simek at xilinx.com>
Acked-by: Sören Brinkmann <soren.brinkmann at xilinx.com>
---

 arch/arm/boot/dts/zynq-7000.dtsi |  5 +++
 arch/arm/mach-zynq/Makefile      |  2 +-
 arch/arm/mach-zynq/common.c      |  1 +
 arch/arm/mach-zynq/common.h      |  3 ++
 arch/arm/mach-zynq/efuse.c       | 75 ++++++++++++++++++++++++++++++++++++++++
 arch/arm/mach-zynq/platsmp.c     |  3 ++
 6 files changed, 88 insertions(+), 1 deletion(-)
 create mode 100644 arch/arm/mach-zynq/efuse.c

diff --git a/arch/arm/boot/dts/zynq-7000.dtsi b/arch/arm/boot/dts/zynq-7000.dtsi
index f3ac9bfe580e..ac37d46b2eab 100644
--- a/arch/arm/boot/dts/zynq-7000.dtsi
+++ b/arch/arm/boot/dts/zynq-7000.dtsi
@@ -305,6 +305,11 @@
 			syscon = <&slcr>;
 		};
 
+		efuse: efuse at f800d000 {
+			compatible = "xlnx,zynq-efuse";
+			reg = <0xf800d000 0x20>;
+		};
+
 		global_timer: timer at f8f00200 {
 			compatible = "arm,cortex-a9-global-timer";
 			reg = <0xf8f00200 0x20>;
diff --git a/arch/arm/mach-zynq/Makefile b/arch/arm/mach-zynq/Makefile
index b03a97eb7501..1fc2d4b53a5e 100644
--- a/arch/arm/mach-zynq/Makefile
+++ b/arch/arm/mach-zynq/Makefile
@@ -3,5 +3,5 @@
 #
 
 # Common support
-obj-y				:= common.o slcr.o pm.o
+obj-y				:= common.o efuse.o slcr.o pm.o
 obj-$(CONFIG_SMP)		+= headsmp.o platsmp.o
diff --git a/arch/arm/mach-zynq/common.c b/arch/arm/mach-zynq/common.c
index 6aba9ebf8041..5f28f7220d48 100644
--- a/arch/arm/mach-zynq/common.c
+++ b/arch/arm/mach-zynq/common.c
@@ -182,6 +182,7 @@ static void __init zynq_map_io(void)
 
 static void __init zynq_irq_init(void)
 {
+	zynq_early_efuse_init();
 	zynq_early_slcr_init();
 	irqchip_init();
 }
diff --git a/arch/arm/mach-zynq/common.h b/arch/arm/mach-zynq/common.h
index e771933db7e8..33742c3308e0 100644
--- a/arch/arm/mach-zynq/common.h
+++ b/arch/arm/mach-zynq/common.h
@@ -25,6 +25,9 @@
 extern void zynq_slcr_cpu_state_write(int cpu, bool die);
 extern u32 zynq_slcr_get_device_id(void);
 
+extern bool zynq_efuse_cpu_state(int cpu);
+extern int zynq_early_efuse_init(void);
+
 #ifdef CONFIG_SMP
 extern char zynq_secondary_trampoline;
 extern char zynq_secondary_trampoline_jump;
diff --git a/arch/arm/mach-zynq/efuse.c b/arch/arm/mach-zynq/efuse.c
new file mode 100644
index 000000000000..d31a5822ec65
--- /dev/null
+++ b/arch/arm/mach-zynq/efuse.c
@@ -0,0 +1,75 @@
+/*
+ * Xilinx EFUSE driver
+ *
+ * Copyright (c) 2016 Xilinx Inc.
+ *
+ * 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.
+ */
+
+#include <linux/io.h>
+#include <linux/of_address.h>
+#include "common.h"
+
+#define EFUSE_STATUS_OFFSET	0x10
+
+/* 0 means cpu1 is working, 1 means cpu1 is broken */
+#define EFUSE_STATUS_CPU_BIT	BIT(7)
+
+void __iomem *zynq_efuse_base;
+
+/**
+ * zynq_efuse_cpu_state - Read/write cpu state
+ * @cpu:	cpu number
+ *
+ * Return: true if cpu is running, false if cpu is broken
+ */
+bool zynq_efuse_cpu_state(int cpu)
+{
+	u32 state;
+
+	if (!cpu)
+		return true;
+
+	state = readl(zynq_efuse_base + EFUSE_STATUS_OFFSET);
+	state &= EFUSE_STATUS_CPU_BIT;
+
+	if (!state)
+		return true;
+
+	return false;
+}
+
+/**
+ * zynq_early_efuse_init - Early efuse init function
+ *
+ * Return:	0 on success, negative errno otherwise.
+ *
+ * Called very early during boot from platform code.
+ */
+int __init zynq_early_efuse_init(void)
+{
+	struct device_node *np;
+
+	np = of_find_compatible_node(NULL, NULL, "xlnx,zynq-efuse");
+	if (!np) {
+		pr_err("%s: no efuse node found\n", __func__);
+		BUG();
+	}
+
+	zynq_efuse_base = of_iomap(np, 0);
+	if (!zynq_efuse_base) {
+		pr_err("%s: Unable to map I/O memory\n", __func__);
+		BUG();
+	}
+
+	np->data = (__force void *)zynq_efuse_base;
+
+	pr_info("%s mapped to %p\n", np->name, zynq_efuse_base);
+
+	of_node_put(np);
+
+	return 0;
+}
diff --git a/arch/arm/mach-zynq/platsmp.c b/arch/arm/mach-zynq/platsmp.c
index caa6d5fe9078..3d81e0f2972f 100644
--- a/arch/arm/mach-zynq/platsmp.c
+++ b/arch/arm/mach-zynq/platsmp.c
@@ -89,6 +89,9 @@ int zynq_cpun_start(u32 address, int cpu)
 
 static int zynq_boot_secondary(unsigned int cpu, struct task_struct *idle)
 {
+	if (!zynq_efuse_cpu_state(cpu))
+		return -1;
+
 	return zynq_cpun_start(__pa_symbol(secondary_startup), cpu);
 }
 
-- 
1.9.1