From: Santosh Shilimkar <santosh.shilimkar@xxxxxx>
On OMAP4+ devices, GIC register context is lost when MPUSS hits
the OSWR(Open Switch Retention). On the CPU wakeup path, ROM code
gets executed and one of the steps in it is to restore the
saved context of the GIC. The ROM Code GIC distributor restoration
is split in two parts: CPU specific register done by each CPU and
common register done by only one CPU.
Below is the abstract flow.
...............................................................
- MPUSS in OSWR state.
- CPU0 wakes up on the event(interrupt) and start executing ROM code.
[..]
- CPU0 executes "GIC Restoration:"
[...]
- CPU0 swicthes to non-secure mode and jumps to OS resume code.
[...]
- CPU0 is online in OS
- CPU0 enables the GIC distributor. GICD.Enable Non-secure = 1
- CPU0 wakes up CPU1 with clock-domain force wakeup method.
- CPU0 continues it's execution.
[..]
- CPU1 wakes up and start executing ROM code.
[..]
- CPU1 executes "GIC Restoration:"
[..]
- CPU1 swicthes to non-secure mode and jumps to OS resume code.
[...]
- CPU1 is online in OS and start executing.
[...] -
GIC Restoration: /* Common routine for HS and GP devices */
{
if (GICD != 1) { /* This will be true in OSWR state */
if (GIC_SAR_BACKUP_STATE == SAVED)
- CPU restores GIC distributor
else
- reconfigure GIC distributor to boot values.
GICD.Enable secure = 1
}
if (GIC_SAR_BACKUP_STATE == SAVED)
- CPU restore its GIC CPU interface registers if saved.
else
- reconfigure its GIC CPU interface registers to boot
values.
}
...............................................................
So as mentioned in the flow, GICD != 1 condition decides how
the GIC registers are handled in ROM code wakeup path from
OSWR. As evident from the flow, ROM code relies on the entire
GICD register value and not specific register bits.
The assumption was valid till CortexA9 r1pX version since there
was only one banked bit to control secure and non-secure GICD.
Secure view which ROM code sees:
bit 0 == Enable Non-secure
Non-secure view which HLOS sees:
bit 0 == Enable secure
But GICD register has changed between CortexA9 r1pX and r2pX.
On r2pX GICD register is composed of 2 bits.
Secure view which ROM code sees:
bit 1 == Enable Non-secure
bit 0 == Enable secure
Non-secure view which HLOS sees:
bit 0 == Enable Non-secure
Hence on OMAP4460(r2pX) devices, if you go through the
above flow again during CPU1 wakeup, GICD == 3 and hence
ROM code fails to understand the real wakeup power state
and reconfigures GIC distributor to boot values. This is
nasty since you loose the entire interrupt controller
context in a live system.
The ROM code fix done on next OMAP4 device (OMAP4470 - r2px) is to
check "GICD.Enable secure != 1" for GIC restoration in OSWR wakeup path.
Since ROM code can't be fixed on OMAP4460 devices, a work around
needs to be implemented. As evident from the flow, as long as
CPU1 sees GICD == 1 in it's wakeup path from OSWR, the issue
won't happen. Below is the flow with the work-around.
...............................................................
- MPUSS in OSWR state.
- CPU0 wakes up on the event(interrupt) and start executing ROM code.
[..]
- CPU0 executes "GIC Restoration:"
[..]
- CPU0 swicthes to non-secure mode and jumps to OS resume code.
[..]
- CPU0 is online in OS.
- CPU0 does GICD.Enable Non-secure = 0
- CPU0 wakes up CPU1 with clock domain force wakeup method.
- CPU0 waits for GICD.Enable Non-secure = 1
- CPU0 coninues it's execution.
[..]
- CPU1 wakes up and start executing ROM code.
[..]
- CPU1 executes "GIC Restoration:"
[..]
- CPU1 swicthes to non-secure mode and jumps to OS resume code.
[..]
- CPU1 is online in OS
- CPU1 does GICD.Enable Non-secure = 1
- CPU1 start executing
[...]
...............................................................
With this procedure, the GIC configuration done between the
CPU0 wakeup and CPU1 wakeup will not be lost but during this
short windows, the CPU0 will not receive interrupts.
The BUG is applicable to only OMAP4460(r2pX) devices.
OMAP4470 (also r2pX) is not affected by this bug because
ROM code has been fixed.
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@xxxxxx>
Signed-off-by: Tero Kristo <t-kristo@xxxxxx>
---
arch/arm/mach-omap2/common.h | 2 +
arch/arm/mach-omap2/omap-headsmp.S | 38 +++++++++++++++++++++++++++++
arch/arm/mach-omap2/omap-mpuss-lowpower.c | 9 ++++++-
arch/arm/mach-omap2/omap-smp.c | 28 ++++++++++++++++++++-
arch/arm/mach-omap2/omap4-common.c | 8 +++++-
arch/arm/mach-omap2/pm.h | 2 +
6 files changed, 84 insertions(+), 3 deletions(-)
diff --git a/arch/arm/mach-omap2/common.h b/arch/arm/mach-omap2/common.h
index be9dfd1..a793ab3 100644
--- a/arch/arm/mach-omap2/common.h
+++ b/arch/arm/mach-omap2/common.h
@@ -246,6 +246,7 @@ static inline void __iomem *omap4_get_scu_base(void)
#endif
extern void __init gic_init_irq(void);
+extern void gic_dist_disable(void);
extern void omap_smc1(u32 fn, u32 arg);
extern void __iomem *omap4_get_sar_ram_base(void);
extern void omap_do_wfi(void);
@@ -253,6 +254,7 @@ extern void omap_do_wfi(void);
#ifdef CONFIG_SMP
/* Needed for secondary core boot */
extern void omap_secondary_startup(void);
+extern void omap_secondary_startup_4460(void);
extern u32 omap_modify_auxcoreboot0(u32 set_mask, u32 clear_mask);
extern void omap_auxcoreboot_addr(u32 cpu_addr);
extern u32 omap_read_auxcoreboot0(void);
diff --git a/arch/arm/mach-omap2/omap-headsmp.S b/arch/arm/mach-omap2/omap-headsmp.S
index 503ac77..7bbb66e 100644
--- a/arch/arm/mach-omap2/omap-headsmp.S
+++ b/arch/arm/mach-omap2/omap-headsmp.S
@@ -18,6 +18,8 @@
#include <linux/linkage.h>
#include <linux/init.h>
+#include <plat/omap44xx.h>
+
__CPUINIT
/*
* OMAP4 specific entry point for secondary CPU to jump from ROM
@@ -43,3 +45,39 @@ hold: ldr r12,=0x103
b secondary_startup
ENDPROC(omap_secondary_startup)
+ENTRY(omap_secondary_startup_4460)
+hold_2: ldr r12,=0x103
+ dsb
+ smc #0 @ read from AuxCoreBoot0
+ mov r0, r0, lsr #9
+ mrc p15, 0, r4, c0, c0, 5
+ and r4, r4, #0x0f
+ cmp r0, r4
+ bne hold_2
+
+ /*
+ * GIC distributor control register has changed between
+ * CortexA9 r1pX and r2pX. The Control Register secure
+ * banked version is now composed of 2 bits:
+ * bit 0 == Secure Enable
+ * bit 1 == Non-Secure Enable
+ * The Non-Secure banked register has not changed
+ * Because the ROM Code is based on the r1pX GIC, the CPU1
+ * GIC restoration will cause a problem to CPU0 Non-Secure SW.
+ * The workaround must be:
+ * 1) Before doing the CPU1 wakeup, CPU0 must disable
+ * the GIC distributor
+ * 2) CPU1 must re-enable the GIC distributor on
+ * it's wakeup path.
+ */
+ ldr r1, =OMAP44XX_GIC_DIST_BASE
+ ldr r0, [r1]
+ orr r0, #1
+ str r0, [r1]
+
+ /*
+ * we've been released from the wait loop,secondary_stack
+ * should now contain the SVC stack for this core
+ */
+ b secondary_startup
+ENDPROC(omap_secondary_startup_4460)
diff --git a/arch/arm/mach-omap2/omap-mpuss-lowpower.c b/arch/arm/mach-omap2/omap-mpuss-lowpower.c
index c79cc0f..0e5f81b 100644
--- a/arch/arm/mach-omap2/omap-mpuss-lowpower.c
+++ b/arch/arm/mach-omap2/omap-mpuss-lowpower.c
@@ -68,6 +68,7 @@ struct omap4_cpu_pm_info {
void __iomem *scu_sar_addr;
void __iomem *wkup_sar_addr;
void __iomem *l2x0_sar_addr;
+ void (*secondary_startup)(void);
};
static DEFINE_PER_CPU(struct omap4_cpu_pm_info, omap4_pm_info);
@@ -301,6 +302,7 @@ int omap4_enter_lowpower(unsigned int cpu, unsigned int power_state)
int __cpuinit omap4_hotplug_cpu(unsigned int cpu, unsigned int power_state)
{
unsigned int cpu_state = 0;
+ struct omap4_cpu_pm_info *pm_info = &per_cpu(omap4_pm_info, cpu);
if (omap_rev() == OMAP4430_REV_ES1_0)
return -ENXIO;
@@ -310,7 +312,7 @@ int __cpuinit omap4_hotplug_cpu(unsigned int cpu, unsigned int power_state)
clear_cpu_prev_pwrst(cpu);
set_cpu_next_pwrst(cpu, power_state);
- set_cpu_wakeup_addr(cpu, virt_to_phys(omap_secondary_startup));
+ set_cpu_wakeup_addr(cpu, virt_to_phys(pm_info->secondary_startup));
scu_pwrst_prepare(cpu, power_state);
/*
@@ -361,6 +363,11 @@ int __init omap4_mpuss_init(void)
pm_info->scu_sar_addr = sar_base + SCU_OFFSET1;
pm_info->wkup_sar_addr = sar_base + CPU1_WAKEUP_NS_PA_ADDR_OFFSET;
pm_info->l2x0_sar_addr = sar_base + L2X0_SAVE_OFFSET1;
+ if (cpu_is_omap446x())
+ pm_info->secondary_startup = omap_secondary_startup_4460;
+ else
+ pm_info->secondary_startup = omap_secondary_startup;
+
pm_info->pwrdm = pwrdm_lookup("cpu1_pwrdm");
if (!pm_info->pwrdm) {
pr_err("Lookup failed for CPU1 pwrdm\n");
diff --git a/arch/arm/mach-omap2/omap-smp.c b/arch/arm/mach-omap2/omap-smp.c
index deffbf1..88e2a19 100644
--- a/arch/arm/mach-omap2/omap-smp.c
+++ b/arch/arm/mach-omap2/omap-smp.c
@@ -30,6 +30,7 @@
#include "iomap.h"
#include "common.h"
#include "clockdomain.h"
+#include "pm.h"
/* SCU base address */
static void __iomem *scu_base;
@@ -104,6 +105,24 @@ int __cpuinit boot_secondary(unsigned int cpu, struct task_struct *idle)
* 4.3.4.2 Power States of CPU0 and CPU1
*/
if (booted) {
+ /*
+ * GIC distributor control register has changed between
+ * CortexA9 r1pX and r2pX. The Control Register secure
+ * banked version is now composed of 2 bits:
+ * bit 0 == Secure Enable
+ * bit 1 == Non-Secure Enable
+ * The Non-Secure banked register has not changed
+ * Because the ROM Code is based on the r1pX GIC, the CPU1
+ * GIC restoration will cause a problem to CPU0 Non-Secure SW.
+ * The workaround must be:
+ * 1) Before doing the CPU1 wakeup, CPU0 must disable
+ * the GIC distributor
+ * 2) CPU1 must re-enable the GIC distributor on
+ * it's wakeup path.
+ */
+ if (IS_PM44XX_ERRATUM(PM_OMAP4_ROM_SMP_BOOT_ERRATUM_GICD))
+ gic_dist_disable();
+
clkdm_wakeup(cpu1_clkdm);
clkdm_allow_idle(cpu1_clkdm);
} else {
@@ -124,13 +143,20 @@ int __cpuinit boot_secondary(unsigned int cpu, struct task_struct *idle)
static void __init wakeup_secondary(void)
{
+ void *startup_addr = omap_secondary_startup;
+
/*
* Write the address of secondary startup routine into the
* AuxCoreBoot1 where ROM code will jump and start executing
* on secondary core once out of WFE
* A barrier is added to ensure that write buffer is drained
*/
- omap_auxcoreboot_addr(virt_to_phys(omap_secondary_startup));
+ if (cpu_is_omap446x()) {
+ startup_addr = omap_secondary_startup_4460;
+ pm44xx_errata |= PM_OMAP4_ROM_SMP_BOOT_ERRATUM_GICD;
+ }
+
+ omap_auxcoreboot_addr(virt_to_phys(startup_addr));
smp_wmb();
/*
diff --git a/arch/arm/mach-omap2/omap4-common.c b/arch/arm/mach-omap2/omap4-common.c
index a8161e5..07ca05b 100644
--- a/arch/arm/mach-omap2/omap4-common.c
+++ b/arch/arm/mach-omap2/omap4-common.c
@@ -40,6 +40,7 @@ static void __iomem *l2cache_base;
#endif
static void __iomem *sar_ram_base;
+static void __iomem *gic_dist_base_addr;
#ifdef CONFIG_OMAP4_ERRATA_I688
/* Used to implement memory barrier on DRAM path */
@@ -94,7 +95,6 @@ void __init omap_barriers_init(void)
void __init gic_init_irq(void)
{
void __iomem *omap_irq_base;
- void __iomem *gic_dist_base_addr;
/* Static mapping, never released */
gic_dist_base_addr = ioremap(OMAP44XX_GIC_DIST_BASE, SZ_4K);
@@ -109,6 +109,12 @@ void __init gic_init_irq(void)
gic_init(0, 29, gic_dist_base_addr, omap_irq_base);
}
+void gic_dist_disable(void)
+{
+ if (gic_dist_base_addr)
+ __raw_writel(0x0, gic_dist_base_addr + GIC_DIST_CTRL);
+}
+
#ifdef CONFIG_CACHE_L2X0
void __iomem *omap4_get_l2cache_base(void)
diff --git a/arch/arm/mach-omap2/pm.h b/arch/arm/mach-omap2/pm.h
index 46ab9d9..d95d1d0 100644
--- a/arch/arm/mach-omap2/pm.h
+++ b/arch/arm/mach-omap2/pm.h
@@ -88,6 +88,8 @@ extern void enable_omap3630_toggle_l2_on_restore(void);
static inline void enable_omap3630_toggle_l2_on_restore(void) { }
#endif /* defined(CONFIG_PM) && defined(CONFIG_ARCH_OMAP3) */
+#define PM_OMAP4_ROM_SMP_BOOT_ERRATUM_GICD (1 << 0)
+
#if defined(CONFIG_ARCH_OMAP4)
extern u16 pm44xx_errata;
#define IS_PM44XX_ERRATUM(id) (pm44xx_errata & (id))
--
1.7.4.1
--
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