The startup code in arm/cpu/arm926ejs preserves the link register across the call to lowlevel_init by using r4:
mov r4, lr /* perserve link reg across call */ bl lowlevel_init /* go setup pll,mux,memory */ mov lr, r4 /* restore link */
The lowlevel_init function for at91 machines based on the same CPU uses r4 and hence corrupts it causing a data abort when it returns to the startup code. This patch fixes this by using r6 instead of r4 in the lowlevel_init function.
Discovered and the fix was tested on a AT91SAM9261 based board.
Signed-off-by: Martin Townsend martin@rufilla.com --- arch/arm/mach-at91/arm926ejs/lowlevel_init.S | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-)
diff --git a/arch/arm/mach-at91/arm926ejs/lowlevel_init.S b/arch/arm/mach-at91/arm926ejs/lowlevel_init.S index 71d7582ce0..994f42eb4a 100644 --- a/arch/arm/mach-at91/arm926ejs/lowlevel_init.S +++ b/arch/arm/mach-at91/arm926ejs/lowlevel_init.S @@ -71,10 +71,10 @@ POS1: str r0, [r1]
/* Reading the PMC Status to detect when the Main Oscillator is enabled */ - mov r4, #AT91_PMC_IXR_MOSCS + mov r6, #AT91_PMC_IXR_MOSCS MOSCS_Loop: ldr r3, [r2] - and r3, r4, r3 + and r3, r6, r3 cmp r3, #AT91_PMC_IXR_MOSCS bne MOSCS_Loop
@@ -89,10 +89,10 @@ MOSCS_Loop: str r0, [r1]
/* Reading the PMC Status register to detect when the PLLA is locked */ - mov r4, #AT91_PMC_IXR_LOCKA + mov r6, #AT91_PMC_IXR_LOCKA MOSCS_Loop1: ldr r3, [r2] - and r3, r4, r3 + and r3, r6, r3 cmp r3, #AT91_PMC_IXR_LOCKA bne MOSCS_Loop1
@@ -109,10 +109,10 @@ MOSCS_Loop1: str r0, [r1]
/* Reading the PMC Status to detect when the Master clock is ready */ - mov r4, #AT91_PMC_IXR_MCKRDY + mov r6, #AT91_PMC_IXR_MCKRDY MCKRDY_Loop: ldr r3, [r2] - and r3, r4, r3 + and r3, r6, r3 cmp r3, #AT91_PMC_IXR_MCKRDY bne MCKRDY_Loop
@@ -120,10 +120,10 @@ MCKRDY_Loop: str r0, [r1]
/* Reading the PMC Status to detect when the Master clock is ready */ - mov r4, #AT91_PMC_IXR_MCKRDY + mov r6, #AT91_PMC_IXR_MCKRDY MCKRDY_Loop1: ldr r3, [r2] - and r3, r4, r3 + and r3, r6, r3 cmp r3, #AT91_PMC_IXR_MCKRDY bne MCKRDY_Loop1 PLL_setup_end: