[PATCH 2/5] ARM: shmobile: apmu: Add debug resource reset for secondary CPU boot

[Simon Horman]

From: Geert Uytterhoeven <geert+rene...@glider.be>

In debug mode (MD21=1), reset requests derived from power-shutoff to the
AP-system CPU cores must be enabled before the AP-system CPU cores
resume from power-shutoff for the first time. Else resume may fail,
causing the system to hang during boot.

As setting these bits is a no-op in normal mode, there's no need to
check the actual state of MD21 first.

Inspired by CPU-specific patches in the BSP by Hisashi Nakamura
<hisashi.nakamura...@renesas.com>.

Signed-off-by: Geert Uytterhoeven <geert+rene...@glider.be>
Tested-by: Hiep Cao Minh <cm-h...@jinso.co.jp>
Signed-off-by: Simon Horman <horms+rene...@verge.net.au>
---
 arch/arm/mach-shmobile/platsmp-apmu.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/arch/arm/mach-shmobile/platsmp-apmu.c 
b/arch/arm/mach-shmobile/platsmp-apmu.c
index 933f9b902405..7e4ca6788be5 100644
--- a/arch/arm/mach-shmobile/platsmp-apmu.c
+++ b/arch/arm/mach-shmobile/platsmp-apmu.c
@@ -35,12 +35,18 @@ static struct {
 #define PSTR_OFFS       0x40           /* Power Status Register */
 #define CPUNCR_OFFS(n) (0x100 + (0x10 * (n)))
                                        /* CPUn Power Status Control Register */
+#define DBGRCR_OFFS    0x180           /* Debug Resource Reset Control Reg. */
 
 /* Power Status Register */
 #define CPUNST(r, n)   (((r) >> (n * 4)) & 3)  /* CPUn Status Bit */
 #define CPUST_RUN      0               /* Run Mode */
 #define CPUST_STANDBY  3               /* CoreStandby Mode */
 
+/* Debug Resource Reset Control Register */
+#define DBGCPUREN      BIT(24)         /* CPU Other Reset Request Enable */
+#define DBGCPUNREN(n)  BIT((n) + 20)   /* CPUn Reset Request Enable */
+#define DBGCPUPREN     BIT(19)         /* CPU Peripheral Reset Req. Enable */
+
 static int __maybe_unused apmu_power_on(void __iomem *p, int bit)
 {
        /* request power on */
@@ -84,6 +90,8 @@ static int __maybe_unused apmu_wrap(int cpu, int (*fn)(void 
__iomem *p, int cpu)
 #ifdef CONFIG_SMP
 static void apmu_init_cpu(struct resource *res, int cpu, int bit)
 {
+       u32 x;
+
        if ((cpu >= ARRAY_SIZE(apmu_cpus)) || apmu_cpus[cpu].iomem)
                return;
 
@@ -91,6 +99,11 @@ static void apmu_init_cpu(struct resource *res, int cpu, int 
bit)
        apmu_cpus[cpu].bit = bit;
 
        pr_debug("apmu ioremap %d %d %pr\n", cpu, bit, res);
+
+       /* Setup for debug mode */
+       x = readl(apmu_cpus[cpu].iomem + DBGRCR_OFFS);
+       x |= DBGCPUREN | DBGCPUNREN(bit) | DBGCPUPREN;
+       writel(x, apmu_cpus[cpu].iomem + DBGRCR_OFFS);
 }
 
 static void apmu_parse_cfg(void (*fn)(struct resource *res, int cpu, int bit),
-- 
2.7.0.rc3.207.g0ac5344