ARM: omap2+: Revert omap-smp.c changes resetting CPU1 during boot

Commit 3251885285e1 ("ARM: OMAP4+: Reset CPU1 properly for kexec") started
unconditionally resetting CPU1 because of a kexec boot issue I was seeing
earlier on omap4 when doing kexec boot between two different kernel
versions.

This caused issues on some systems. We should only reset CPU1 as a last
resort option, and try to avoid it where possible. Doing an unconditional
CPU1 reset causes issues for example when booting a bootloader configured
secure OS running on CPU1 as reported by Andrew F. Davis <afd@ti.com>.

We can't completely remove the reset of CPU1 as it would break kexec
booting from older kernels. But we can limit the CPU1 reset to cases
where CPU1 is wrongly parked within the memory area used by the booting
kernel. Then later on we can add support for parking CPU1 for kexec out
of the SDRAM back to bootrom.

So let's first fix the regression reported by Andrew by making CPU1 reset
conditional. To do this, we need to:

1. Save configured AUX_CORE_BOOT_1 for later

2. Modify AUX_CORE_BOOT_0 reading code to for HS SoCs to return
   the whole register instead of the CPU mask

3. Check if CPU1 is wrongly parked into the booting kernel by the
   previous kernel and reset if needed

Fixes: 3251885285e1 ("ARM: OMAP4+: Reset CPU1 properly for kexec")
Reported-by: Andrew F. Davis <afd@ti.com>
Cc: Andrew F. Davis <afd@ti.com>
Cc: Keerthy <j-keerthy@ti.com>
Cc: Russell King <rmk+kernel@armlinux.org.uk>
Cc: Santosh Shilimkar <ssantosh@kernel.org>
Cc: Tero Kristo <t-kristo@ti.com>
Tested-by: Keerthy <j-keerthy@ti.com>
Tested-by: Andrew F. Davis <afd@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>

5 files changed, 96 insertions, 20 deletions

diff --git a/arch/arm/mach-omap2/common.h b/arch/arm/mach-omap2/common.h
index c4f2ace91ea2..3089d3bfa19b 100644
--- a/arch/arm/mach-omap2/common.h
+++ b/arch/arm/mach-omap2/common.h
@@ -270,6 +270,7 @@ extern const struct smp_operations omap4_smp_ops;
 extern int omap4_mpuss_init(void);
 extern int omap4_enter_lowpower(unsigned int cpu, unsigned int power_state);
 extern int omap4_hotplug_cpu(unsigned int cpu, unsigned int power_state);
+extern u32 omap4_get_cpu1_ns_pa_addr(void);
 #else
 static inline int omap4_enter_lowpower(unsigned int cpu,
                                         unsigned int power_state)
diff --git a/arch/arm/mach-omap2/omap-hotplug.c b/arch/arm/mach-omap2/omap-hotplug.c
index d3fb5661bb5d..433db6d0b073 100644
--- a/arch/arm/mach-omap2/omap-hotplug.c
+++ b/arch/arm/mach-omap2/omap-hotplug.c
@@ -50,7 +50,7 @@ void omap4_cpu_die(unsigned int cpu)
                 omap4_hotplug_cpu(cpu, PWRDM_POWER_OFF);
 
                 if (omap_secure_apis_support())
-                        boot_cpu = omap_read_auxcoreboot0();
+                        boot_cpu = omap_read_auxcoreboot0() >> 9;
                 else
                         boot_cpu =
                                 readl_relaxed(base + OMAP_AUX_CORE_BOOT_0) >> 5;
diff --git a/arch/arm/mach-omap2/omap-mpuss-lowpower.c b/arch/arm/mach-omap2/omap-mpuss-lowpower.c
index 113ab2dd2ee9..03ec6d307c82 100644
--- a/arch/arm/mach-omap2/omap-mpuss-lowpower.c
+++ b/arch/arm/mach-omap2/omap-mpuss-lowpower.c
@@ -64,6 +64,7 @@
 #include "prm-regbits-44xx.h"
 
 static void __iomem *sar_base;
+static u32 old_cpu1_ns_pa_addr;
 
 #if defined(CONFIG_PM) && defined(CONFIG_SMP)
 
@@ -212,6 +213,11 @@ static void __init save_l2x0_context(void)
 {}
 #endif
 
+u32 omap4_get_cpu1_ns_pa_addr(void)
+{
+        return old_cpu1_ns_pa_addr;
+}
+
 /**
  * omap4_enter_lowpower: OMAP4 MPUSS Low Power Entry Function
  * The purpose of this function is to manage low power programming
@@ -460,22 +466,30 @@ int __init omap4_mpuss_init(void)
 void __init omap4_mpuss_early_init(void)
 {
         unsigned long startup_pa;
+        void __iomem *ns_pa_addr;
 
-        if (!(cpu_is_omap44xx() || soc_is_omap54xx()))
+        if (!(soc_is_omap44xx() || soc_is_omap54xx()))
                 return;
 
         sar_base = omap4_get_sar_ram_base();
 
-        if (cpu_is_omap443x())
+        /* Save old NS_PA_ADDR for validity checks later on */
+        if (soc_is_omap44xx())
+                ns_pa_addr = sar_base + CPU1_WAKEUP_NS_PA_ADDR_OFFSET;
+        else
+                ns_pa_addr = sar_base + OMAP5_CPU1_WAKEUP_NS_PA_ADDR_OFFSET;
+        old_cpu1_ns_pa_addr = readl_relaxed(ns_pa_addr);
+
+        if (soc_is_omap443x())
                 startup_pa = __pa_symbol(omap4_secondary_startup);
-        else if (cpu_is_omap446x())
+        else if (soc_is_omap446x())
                 startup_pa = __pa_symbol(omap4460_secondary_startup);
         else if ((__boot_cpu_mode & MODE_MASK) == HYP_MODE)
                 startup_pa = __pa_symbol(omap5_secondary_hyp_startup);
         else
                 startup_pa = __pa_symbol(omap5_secondary_startup);
 
-        if (cpu_is_omap44xx())
+        if (soc_is_omap44xx())
                 writel_relaxed(startup_pa, sar_base +
                                CPU1_WAKEUP_NS_PA_ADDR_OFFSET);
         else
diff --git a/arch/arm/mach-omap2/omap-smc.S b/arch/arm/mach-omap2/omap-smc.S
index fd90125bffc7..72506e6cf9e7 100644
--- a/arch/arm/mach-omap2/omap-smc.S
+++ b/arch/arm/mach-omap2/omap-smc.S
@@ -94,6 +94,5 @@ ENTRY(omap_read_auxcoreboot0)
         ldr     r12, =0x103
         dsb
         smc     #0
-        mov     r0, r0, lsr #9
         ldmfd   sp!, {r2-r12, pc}
 ENDPROC(omap_read_auxcoreboot0)
diff --git a/arch/arm/mach-omap2/omap-smp.c b/arch/arm/mach-omap2/omap-smp.c
index 003353b0b794..3faf454ba487 100644
--- a/arch/arm/mach-omap2/omap-smp.c
+++ b/arch/arm/mach-omap2/omap-smp.c
@@ -21,6 +21,7 @@
 #include <linux/io.h>
 #include <linux/irqchip/arm-gic.h>
 
+#include <asm/sections.h>
 #include <asm/smp_scu.h>
 #include <asm/virt.h>
 
@@ -40,10 +41,14 @@
 
 #define OMAP5_CORE_COUNT        0x2
 
+#define AUX_CORE_BOOT0_GP_RELEASE       0x020
+#define AUX_CORE_BOOT0_HS_RELEASE       0x200
+
 struct omap_smp_config {
         unsigned long cpu1_rstctrl_pa;
         void __iomem *cpu1_rstctrl_va;
         void __iomem *scu_base;
+        void __iomem *wakeupgen_base;
         void *startup_addr;
 };
 
@@ -140,7 +145,6 @@ static int omap4_boot_secondary(unsigned int cpu, struct task_struct *idle)
         static struct clockdomain *cpu1_clkdm;
         static bool booted;
         static struct powerdomain *cpu1_pwrdm;
-        void __iomem *base = omap_get_wakeupgen_base();
 
         /*
          * Set synchronisation state between this boot processor
@@ -155,9 +159,11 @@ static int omap4_boot_secondary(unsigned int cpu, struct task_struct *idle)
          * A barrier is added to ensure that write buffer is drained
          */
         if (omap_secure_apis_support())
-                omap_modify_auxcoreboot0(0x200, 0xfffffdff);
+                omap_modify_auxcoreboot0(AUX_CORE_BOOT0_HS_RELEASE,
+                                         0xfffffdff);
         else
-                writel_relaxed(0x20, base + OMAP_AUX_CORE_BOOT_0);
+                writel_relaxed(AUX_CORE_BOOT0_GP_RELEASE,
+                               cfg.wakeupgen_base + OMAP_AUX_CORE_BOOT_0);
 
         if (!cpu1_clkdm && !cpu1_pwrdm) {
                 cpu1_clkdm = clkdm_lookup("mpu1_clkdm");
@@ -261,9 +267,72 @@ static void __init omap4_smp_init_cpus(void)
                 set_cpu_possible(i, true);
 }
 
+/*
+ * For now, just make sure the start-up address is not within the booting
+ * kernel space as that means we just overwrote whatever secondary_startup()
+ * code there was.
+ */
+static bool __init omap4_smp_cpu1_startup_valid(unsigned long addr)
+{
+        if ((addr >= __pa(PAGE_OFFSET)) && (addr <= __pa(__bss_start)))
+                return false;
+
+        return true;
+}
+
+/*
+ * We may need to reset CPU1 before configuring, otherwise kexec boot can end
+ * up trying to use old kernel startup address or suspend-resume will
+ * occasionally fail to bring up CPU1 on 4430 if CPU1 fails to enter deeper
+ * idle states.
+ */
+static void __init omap4_smp_maybe_reset_cpu1(struct omap_smp_config *c)
+{
+        unsigned long cpu1_startup_pa, cpu1_ns_pa_addr;
+        bool needs_reset = false;
+        u32 released;
+
+        if (omap_secure_apis_support())
+                released = omap_read_auxcoreboot0() & AUX_CORE_BOOT0_HS_RELEASE;
+        else
+                released = readl_relaxed(cfg.wakeupgen_base +
+                                         OMAP_AUX_CORE_BOOT_0) &
+                                                AUX_CORE_BOOT0_GP_RELEASE;
+        if (released) {
+                pr_warn("smp: CPU1 not parked?\n");
+
+                return;
+        }
+
+        cpu1_startup_pa = readl_relaxed(cfg.wakeupgen_base +
+                                        OMAP_AUX_CORE_BOOT_1);
+        cpu1_ns_pa_addr = omap4_get_cpu1_ns_pa_addr();
+
+        /* Did the configured secondary_startup() get overwritten? */
+        if (!omap4_smp_cpu1_startup_valid(cpu1_startup_pa))
+                needs_reset = true;
+
+        /*
+         * If omap4 or 5 has NS_PA_ADDR configured, CPU1 may be in a
+         * deeper idle state in WFI and will wake to an invalid address.
+         */
+        if ((soc_is_omap44xx() || soc_is_omap54xx()) &&
+            !omap4_smp_cpu1_startup_valid(cpu1_ns_pa_addr))
+                needs_reset = true;
+
+        if (!needs_reset || !c->cpu1_rstctrl_va)
+                return;
+
+        pr_info("smp: CPU1 parked within kernel, needs reset (0x%lx 0x%lx)\n",
+                cpu1_startup_pa, cpu1_ns_pa_addr);
+
+        writel_relaxed(1, c->cpu1_rstctrl_va);
+        readl_relaxed(c->cpu1_rstctrl_va);
+        writel_relaxed(0, c->cpu1_rstctrl_va);
+}
+
 static void __init omap4_smp_prepare_cpus(unsigned int max_cpus)
 {
-        void __iomem *base = omap_get_wakeupgen_base();
         const struct omap_smp_config *c = NULL;
 
         if (soc_is_omap443x())
@@ -281,6 +350,7 @@ static void __init omap4_smp_prepare_cpus(unsigned int max_cpus)
         /* Must preserve cfg.scu_base set earlier */
         cfg.cpu1_rstctrl_pa = c->cpu1_rstctrl_pa;
         cfg.startup_addr = c->startup_addr;
+        cfg.wakeupgen_base = omap_get_wakeupgen_base();
 
         if (soc_is_dra74x() || soc_is_omap54xx()) {
                 if ((__boot_cpu_mode & MODE_MASK) == HYP_MODE)
@@ -299,15 +369,7 @@ static void __init omap4_smp_prepare_cpus(unsigned int max_cpus)
         if (cfg.scu_base)
                 scu_enable(cfg.scu_base);
 
-        /*
-         * Reset CPU1 before configuring, otherwise kexec will
-         * end up trying to use old kernel startup address.
-         */
-        if (cfg.cpu1_rstctrl_va) {
-                writel_relaxed(1, cfg.cpu1_rstctrl_va);
-                readl_relaxed(cfg.cpu1_rstctrl_va);
-                writel_relaxed(0, cfg.cpu1_rstctrl_va);
-        }
+        omap4_smp_maybe_reset_cpu1(&cfg);
 
         /*
          * Write the address of secondary startup routine into the
@@ -319,7 +381,7 @@ static void __init omap4_smp_prepare_cpus(unsigned int max_cpus)
                 omap_auxcoreboot_addr(__pa_symbol(cfg.startup_addr));
         else
                 writel_relaxed(__pa_symbol(cfg.startup_addr),
-                               base + OMAP_AUX_CORE_BOOT_1);
+                               cfg.wakeupgen_base + OMAP_AUX_CORE_BOOT_1);
 }
 
 const struct smp_operations omap4_smp_ops __initconst = {