[PATCHv8 5/5] ARM: OMAP4: retrigger localtimers after re-enabling gic

[Tero Kristo]

From: Colin Cross <ccross at android.com>

'Workaround for ROM bug because of CA9 r2pX gic control'
register change disables the gic distributor while the secondary
cpu is being booted.  If a localtimer interrupt on the primary cpu
occurs when the distributor is turned off, the interrupt is lost,
and the localtimer never fires again.

Make the primary cpu wait for the secondary cpu to reenable the
gic distributor (with interrupts off for safety), and then
check if the pending bit is set in the localtimer but not the
gic.  If so, ack it in the localtimer, and reset the timer with
the minimum timeout to trigger a new timer interrupt.

Signed-off-by: Colin Cross <ccross at android.com>
[s-jan at ti.com: adapted to k3.4 + validated functionality]
Signed-off-by: Sebastien Jan <s-jan at ti.com>
[t-kristo at ti.com: dropped generic ARM kernel exports from the code, rebased
 to mainline]
Signed-off-by: Tero Kristo <t-kristo at ti.com>
---
 arch/arm/mach-omap2/common.h       |    2 ++
 arch/arm/mach-omap2/omap-smp.c     |   13 ++++++++++++-
 arch/arm/mach-omap2/omap4-common.c |   32 ++++++++++++++++++++++++++++++++
 3 files changed, 46 insertions(+), 1 deletions(-)

diff --git a/arch/arm/mach-omap2/common.h b/arch/arm/mach-omap2/common.h
index edbf27d..6ea837a 100644
--- a/arch/arm/mach-omap2/common.h
+++ b/arch/arm/mach-omap2/common.h
@@ -269,6 +269,8 @@ static inline void __iomem *omap4_get_scu_base(void)
 
 extern void __init gic_init_irq(void);
 extern void gic_dist_disable(void);
+extern bool gic_dist_disabled(void);
+extern void gic_timer_retrigger(void);
 extern void omap_smc1(u32 fn, u32 arg);
 extern void __iomem *omap4_get_sar_ram_base(void);
 extern void omap_do_wfi(void);
diff --git a/arch/arm/mach-omap2/omap-smp.c b/arch/arm/mach-omap2/omap-smp.c
index 28d6201..b9738e2 100644
--- a/arch/arm/mach-omap2/omap-smp.c
+++ b/arch/arm/mach-omap2/omap-smp.c
@@ -134,11 +134,22 @@ int __cpuinit boot_secondary(unsigned int cpu, struct task_struct *idle)
 		 * 2) CPU1 must re-enable the GIC distributor on
 		 * it's wakeup path.
 		 */
-		if (IS_PM44XX_ERRATUM(PM_OMAP4_ROM_SMP_BOOT_ERRATUM_GICD))
+		if (IS_PM44XX_ERRATUM(PM_OMAP4_ROM_SMP_BOOT_ERRATUM_GICD)) {
+			local_irq_disable();
 			gic_dist_disable();
+		}
 
 		clkdm_wakeup(cpu1_clkdm);
 		clkdm_allow_idle(cpu1_clkdm);
+
+		if (IS_PM44XX_ERRATUM(PM_OMAP4_ROM_SMP_BOOT_ERRATUM_GICD)) {
+			while (gic_dist_disabled()) {
+				udelay(1);
+				cpu_relax();
+			}
+			gic_timer_retrigger();
+			local_irq_enable();
+		}
 	} else {
 		dsb_sev();
 		booted = true;
diff --git a/arch/arm/mach-omap2/omap4-common.c b/arch/arm/mach-omap2/omap4-common.c
index 91d42bb..852c010 100644
--- a/arch/arm/mach-omap2/omap4-common.c
+++ b/arch/arm/mach-omap2/omap4-common.c
@@ -14,6 +14,7 @@
 #include <linux/kernel.h>
 #include <linux/init.h>
 #include <linux/io.h>
+#include <linux/irq.h>
 #include <linux/platform_device.h>
 #include <linux/memblock.h>
 
@@ -21,6 +22,7 @@
 #include <asm/hardware/cache-l2x0.h>
 #include <asm/mach/map.h>
 #include <asm/memblock.h>
+#include <asm/smp_twd.h>
 #include <linux/of_irq.h>
 #include <linux/of_platform.h>
 
@@ -43,6 +45,7 @@ static void __iomem *l2cache_base;
 
 static void __iomem *sar_ram_base;
 static void __iomem *gic_dist_base_addr;
+static void __iomem *twd_base;
 
 #ifdef CONFIG_OMAP4_ERRATA_I688
 /* Used to implement memory barrier on DRAM path */
@@ -102,6 +105,9 @@ void __init gic_init_irq(void)
 	gic_dist_base_addr = ioremap(OMAP44XX_GIC_DIST_BASE, SZ_4K);
 	BUG_ON(!gic_dist_base_addr);
 
+	twd_base = ioremap(OMAP44XX_LOCAL_TWD_BASE, SZ_4K);
+	BUG_ON(!twd_base);
+
 	/* Static mapping, never released */
 	omap_irq_base = ioremap(OMAP44XX_GIC_CPU_BASE, SZ_512);
 	BUG_ON(!omap_irq_base);
@@ -117,6 +123,32 @@ void gic_dist_disable(void)
 		__raw_writel(0x0, gic_dist_base_addr + GIC_DIST_CTRL);
 }
 
+bool gic_dist_disabled(void)
+{
+	return !(__raw_readl(gic_dist_base_addr + GIC_DIST_CTRL) & 0x1);
+}
+
+void gic_timer_retrigger(void)
+{
+	u32 twd_int = __raw_readl(twd_base + TWD_TIMER_INTSTAT);
+	u32 gic_int = __raw_readl(gic_dist_base_addr + GIC_DIST_PENDING_SET);
+	u32 twd_ctrl = __raw_readl(twd_base + TWD_TIMER_CONTROL);
+
+	if (twd_int && !(gic_int & BIT(OMAP44XX_IRQ_LOCALTIMER))) {
+		/*
+		 * The local timer interrupt got lost while the distributor was
+		 * disabled.  Ack the pending interrupt, and retrigger it.
+		 */
+		pr_warn("%s: lost localtimer interrupt\n", __func__);
+		__raw_writel(1, twd_base + TWD_TIMER_INTSTAT);
+		if (!(twd_ctrl & TWD_TIMER_CONTROL_PERIODIC)) {
+			__raw_writel(1, twd_base + TWD_TIMER_COUNTER);
+			twd_ctrl |= TWD_TIMER_CONTROL_ENABLE;
+			__raw_writel(twd_ctrl, twd_base + TWD_TIMER_CONTROL);
+		}
+	}
+}
+
 #ifdef CONFIG_CACHE_L2X0
 
 void __iomem *omap4_get_l2cache_base(void)
-- 
1.7.4.1