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Subject[PATCH 3/3] arm: zynq: slcr: Use read-modify-write for register writes
Date
zynq_slcr_cpu_start/stop() ignored the current register state when
writing to a register. Fixing this by implementing proper
read-modify-write.

Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com>
---
arch/arm/mach-zynq/slcr.c | 16 ++++++++--------
1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/arch/arm/mach-zynq/slcr.c b/arch/arm/mach-zynq/slcr.c
index 44a4ab6..1836d5a 100644
--- a/arch/arm/mach-zynq/slcr.c
+++ b/arch/arm/mach-zynq/slcr.c
@@ -61,11 +61,11 @@ void zynq_slcr_system_reset(void)
*/
void zynq_slcr_cpu_start(int cpu)
{
- /* enable CPUn */
- writel(SLCR_A9_CPU_CLKSTOP << cpu,
- zynq_slcr_base + SLCR_A9_CPU_RST_CTRL_OFFSET);
- /* enable CLK for CPUn */
- writel(0x0 << cpu, zynq_slcr_base + SLCR_A9_CPU_RST_CTRL_OFFSET);
+ u32 reg = readl(zynq_slcr_base + SLCR_A9_CPU_RST_CTRL_OFFSET);
+ reg &= ~(SLCR_A9_CPU_RST << cpu);
+ writel(reg, zynq_slcr_base + SLCR_A9_CPU_RST_CTRL_OFFSET);
+ reg &= ~(SLCR_A9_CPU_CLKSTOP << cpu);
+ writel(reg, zynq_slcr_base + SLCR_A9_CPU_RST_CTRL_OFFSET);
}

/**
@@ -74,9 +74,9 @@ void zynq_slcr_cpu_start(int cpu)
*/
void zynq_slcr_cpu_stop(int cpu)
{
- /* stop CLK and reset CPUn */
- writel((SLCR_A9_CPU_CLKSTOP | SLCR_A9_CPU_RST) << cpu,
- zynq_slcr_base + SLCR_A9_CPU_RST_CTRL_OFFSET);
+ u32 reg = readl(zynq_slcr_base + SLCR_A9_CPU_RST_CTRL_OFFSET);
+ reg |= (SLCR_A9_CPU_CLKSTOP | SLCR_A9_CPU_RST) << cpu;
+ writel(reg, zynq_slcr_base + SLCR_A9_CPU_RST_CTRL_OFFSET);
}

/**
--
1.8.3.3


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