[U-Boot] [PATCH 5/6] ARM: Introduce function to switch to hypervisor mode

Keerthy
2016-09-14T05:13:32Z

On some of the SoCs one cannot enable hypervisor mode directly from the
u-boot because the ROM code puts the chip to supervisor mode after it
jumps to boot loader. Hence introduce a weak function which can be
overridden based on the SoC type and switch to hypervisor mode in a
custom way.

Cc: beagleboard-x15 at googlegroups.com
Signed-off-by: Keerthy <j-keerthy@ti.com>
---
arch/arm/cpu/armv7/start.S | 21 +++++++++++++++++++++
arch/arm/include/asm/system.h | 4 ++++
2 files changed, 25 insertions(+)

diff --git a/arch/arm/cpu/armv7/start.S b/arch/arm/cpu/armv7/start.S
index 691e5d3..7eee54b 100644
--- a/arch/arm/cpu/armv7/start.S
+++ b/arch/arm/cpu/armv7/start.S
@@ -17,6 +17,7 @@
#include <config.h>
#include <asm/system.h>
#include <linux/linkage.h>
+#include <asm/armv7.h>

/*************************************************************************
*
@@ -30,11 +31,24 @@

.globl reset
.globl save_boot_params_ret
+#ifdef CONFIG_ARMV7_LPAE
+ .global switch_to_hypervisor_ret
+#endif

reset:
/* Allow the board to save important registers */
b save_boot_params
save_boot_params_ret:
+#ifdef CONFIG_ARMV7_LPAE
+/*
+ * check for Hypervisor support
+ */
+ mrc p15, 0, r0, c0, c1, 1 @ read ID_PFR1
+ and r0, r0, #CPUID_ARM_VIRT_MASK @ mask virtualization bits
+ cmp r0, #(1 << CPUID_ARM_VIRT_SHIFT)
+ beq switch_to_hypervisor
+switch_to_hypervisor_ret:
+#endif
/*
* disable interrupts (FIQ and IRQ), also set the cpu to SVC32 mode,
* except if in HYP mode already
@@ -103,6 +117,13 @@ ENTRY(save_boot_params)
ENDPROC(save_boot_params)
.weak save_boot_params

+#ifdef CONFIG_ARMV7_LPAE
+ENTRY(switch_to_hypervisor)
+ b switch_to_hypervisor_ret
+ENDPROC(switch_to_hypervisor)
+ .weak switch_to_hypervisor
+#endif
+
/*************************************************************************
*
* cpu_init_cp15
diff --git a/arch/arm/include/asm/system.h b/arch/arm/include/asm/system.h
index 7b7b867..c18e1e3 100644
--- a/arch/arm/include/asm/system.h
+++ b/arch/arm/include/asm/system.h
@@ -223,6 +223,10 @@ void __noreturn psci_system_reset(bool smc);
*/
void save_boot_params_ret(void);

+#ifdef CONFIG_ARMV7_LPAE
+void switch_to_hypervisor_ret(void);
+#endif
+
#define nop() __asm__ __volatile__("mov\tr0,r0\t@ nop\n\t");

#ifdef __ARM_ARCH_7A__
--
1.9.1