arm: zynq: slcr: Use read-modify-write for register writes

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>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>

1 files changed, 8 insertions, 8 deletions

diff --git a/arch/arm/mach-zynq/slcr.c b/arch/arm/mach-zynq/slcr.c
index 44a4ab62e9a8..1836d5a34606 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);
 }
 
 /**