[PATCH 4.2 29/54] ARM: ux500: simplify secondary CPU boot

From: Greg Kroah-Hartman
Date: Fri Oct 23 2015 - 14:26:48 EST

4.2-stable review patch. If anyone has any objections, please let me know.

------------------

From: Linus Walleij <linus.walleij@xxxxxxxxxx>

commit c00def71efd919e8ae835a25f4f4c80a4b2d36d3 upstream.

This removes a lot of ancient cruft from the Ux500 SMP boot.
Instead of the pen grab/release, just point the ROM to
secondary_boot() and start the second CPU there, then send
the IPI.

Use our own SMP enable method. This enables us to remove the
last static mapping and get both CPUs booting properly.

Tested this and it just works.

Signed-off-by: Linus Walleij <linus.walleij@xxxxxxxxxx>
Signed-off-by: Olof Johansson <olof@xxxxxxxxx>
Signed-off-by: Kevin Hilman <khilman@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
arch/arm/mach-ux500/Makefile | 2
arch/arm/mach-ux500/cpu-db8500.c | 1
arch/arm/mach-ux500/headsmp.S | 37 ----------
arch/arm/mach-ux500/platsmp.c | 132 +++++++++++----------------------------
arch/arm/mach-ux500/setup.h | 1
5 files changed, 40 insertions(+), 133 deletions(-)

--- a/arch/arm/mach-ux500/Makefile
+++ b/arch/arm/mach-ux500/Makefile
@@ -7,7 +7,7 @@ obj-$(CONFIG_CACHE_L2X0) += cache-l2x0.o
obj-$(CONFIG_UX500_SOC_DB8500) += cpu-db8500.o
obj-$(CONFIG_MACH_MOP500) += board-mop500-regulators.o \
board-mop500-audio.o
-obj-$(CONFIG_SMP) += platsmp.o headsmp.o
+obj-$(CONFIG_SMP) += platsmp.o
obj-$(CONFIG_HOTPLUG_CPU) += hotplug.o
obj-$(CONFIG_PM_GENERIC_DOMAINS) += pm_domains.o

--- a/arch/arm/mach-ux500/cpu-db8500.c
+++ b/arch/arm/mach-ux500/cpu-db8500.c
@@ -154,7 +154,6 @@ static const char * stericsson_dt_platfo
};

DT_MACHINE_START(U8500_DT, "ST-Ericsson Ux5x0 platform (Device Tree Support)")
- .smp = smp_ops(ux500_smp_ops),
.map_io = u8500_map_io,
.init_irq = ux500_init_irq,
/* we re-use nomadik timer here */
--- a/arch/arm/mach-ux500/headsmp.S
+++ /dev/null
@@ -1,37 +0,0 @@
-/*
- * Copyright (c) 2009 ST-Ericsson
- * This file is based ARM Realview platform
- * Copyright (c) 2003 ARM Limited
- * All Rights Reserved
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation.
- */
-#include <linux/linkage.h>
-#include <linux/init.h>
-
-/*
- * U8500 specific entry point for secondary CPUs.
- */
-ENTRY(u8500_secondary_startup)
- mrc p15, 0, r0, c0, c0, 5
- and r0, r0, #15
- adr r4, 1f
- ldmia r4, {r5, r6}
- sub r4, r4, r5
- add r6, r6, r4
-pen: ldr r7, [r6]
- cmp r7, r0
- bne pen
-
- /*
- * we've been released from the holding pen: secondary_stack
- * should now contain the SVC stack for this core
- */
- b secondary_startup
-ENDPROC(u8500_secondary_startup)
-
- .align 2
-1: .long .
- .long pen_release
--- a/arch/arm/mach-ux500/platsmp.c
+++ b/arch/arm/mach-ux500/platsmp.c
@@ -28,135 +28,81 @@
#include "db8500-regs.h"
#include "id.h"

-static void __iomem *scu_base;
-static void __iomem *backupram;
-
-/* This is called from headsmp.S to wakeup the secondary core */
-extern void u8500_secondary_startup(void);
-
-/*
- * Write pen_release in a way that is guaranteed to be visible to all
- * observers, irrespective of whether they're taking part in coherency
- * or not. This is necessary for the hotplug code to work reliably.
- */
-static void write_pen_release(int val)
-{
- pen_release = val;
- smp_wmb();
- sync_cache_w(&pen_release);
-}
-
-static DEFINE_SPINLOCK(boot_lock);
-
-static void ux500_secondary_init(unsigned int cpu)
-{
- /*
- * let the primary processor know we're out of the
- * pen, then head off into the C entry point
- */
- write_pen_release(-1);
-
- /*
- * Synchronise with the boot thread.
- */
- spin_lock(&boot_lock);
- spin_unlock(&boot_lock);
-}
+/* Magic triggers in backup RAM */
+#define UX500_CPU1_JUMPADDR_OFFSET 0x1FF4
+#define UX500_CPU1_WAKEMAGIC_OFFSET 0x1FF0

-static int ux500_boot_secondary(unsigned int cpu, struct task_struct *idle)
+static void wakeup_secondary(void)
{
- unsigned long timeout;
-
- /*
- * set synchronisation state between this boot processor
- * and the secondary one
- */
- spin_lock(&boot_lock);
-
- /*
- * The secondary processor is waiting to be released from
- * the holding pen - release it, then wait for it to flag
- * that it has been released by resetting pen_release.
- */
- write_pen_release(cpu_logical_map(cpu));
-
- arch_send_wakeup_ipi_mask(cpumask_of(cpu));
+ struct device_node *np;
+ static void __iomem *backupram;

- timeout = jiffies + (1 * HZ);
- while (time_before(jiffies, timeout)) {
- if (pen_release == -1)
- break;
+ np = of_find_compatible_node(NULL, NULL, "ste,dbx500-backupram");
+ if (!np) {
+ pr_err("No backupram base address\n");
+ return;
+ }
+ backupram = of_iomap(np, 0);
+ of_node_put(np);
+ if (!backupram) {
+ pr_err("No backupram remap\n");
+ return;
}

/*
- * now the secondary core is starting up let it run its
- * calibrations, then wait for it to finish
- */
- spin_unlock(&boot_lock);
-
- return pen_release != -1 ? -ENOSYS : 0;
-}
-
-static void __init wakeup_secondary(void)
-{
- /*
* write the address of secondary startup into the backup ram register
* at offset 0x1FF4, then write the magic number 0xA1FEED01 to the
* backup ram register at offset 0x1FF0, which is what boot rom code
- * is waiting for. This would wake up the secondary core from WFE
+ * is waiting for. This will wake up the secondary core from WFE.
*/
-#define UX500_CPU1_JUMPADDR_OFFSET 0x1FF4
- __raw_writel(virt_to_phys(u8500_secondary_startup),
- backupram + UX500_CPU1_JUMPADDR_OFFSET);
-
-#define UX500_CPU1_WAKEMAGIC_OFFSET 0x1FF0
- __raw_writel(0xA1FEED01,
- backupram + UX500_CPU1_WAKEMAGIC_OFFSET);
+ writel(virt_to_phys(secondary_startup),
+ backupram + UX500_CPU1_JUMPADDR_OFFSET);
+ writel(0xA1FEED01,
+ backupram + UX500_CPU1_WAKEMAGIC_OFFSET);

/* make sure write buffer is drained */
mb();
+ iounmap(backupram);
}

-/*
- * Initialise the CPU possible map early - this describes the CPUs
- * which may be present or become present in the system.
- */
-static void __init ux500_smp_init_cpus(void)
+static void __init ux500_smp_prepare_cpus(unsigned int max_cpus)
{
- unsigned int i, ncores;
struct device_node *np;
+ static void __iomem *scu_base;
+ unsigned int ncores;
+ int i;

np = of_find_compatible_node(NULL, NULL, "arm,cortex-a9-scu");
+ if (!np) {
+ pr_err("No SCU base address\n");
+ return;
+ }
scu_base = of_iomap(np, 0);
of_node_put(np);
- if (!scu_base)
+ if (!scu_base) {
+ pr_err("No SCU remap\n");
return;
- backupram = ioremap(U8500_BACKUPRAM0_BASE, SZ_8K);
- ncores = scu_get_core_count(scu_base);
-
- /* sanity check */
- if (ncores > nr_cpu_ids) {
- pr_warn("SMP: %u cores greater than maximum (%u), clipping\n",
- ncores, nr_cpu_ids);
- ncores = nr_cpu_ids;
}

+ scu_enable(scu_base);
+ ncores = scu_get_core_count(scu_base);
for (i = 0; i < ncores; i++)
set_cpu_possible(i, true);
+ iounmap(scu_base);
}

-static void __init ux500_smp_prepare_cpus(unsigned int max_cpus)
+static int ux500_boot_secondary(unsigned int cpu, struct task_struct *idle)
{
- scu_enable(scu_base);
wakeup_secondary();
+ arch_send_wakeup_ipi_mask(cpumask_of(cpu));
+ return 0;
}

struct smp_operations ux500_smp_ops __initdata = {
- .smp_init_cpus = ux500_smp_init_cpus,
.smp_prepare_cpus = ux500_smp_prepare_cpus,
- .smp_secondary_init = ux500_secondary_init,
.smp_boot_secondary = ux500_boot_secondary,
#ifdef CONFIG_HOTPLUG_CPU
.cpu_die = ux500_cpu_die,
#endif
};
+CPU_METHOD_OF_DECLARE(ux500_smp, "ste,dbx500-smp", &ux500_smp_ops);
--- a/arch/arm/mach-ux500/setup.h
+++ b/arch/arm/mach-ux500/setup.h
@@ -26,7 +26,6 @@ extern struct device *ux500_soc_device_i

extern void ux500_timer_init(void);

-extern struct smp_operations ux500_smp_ops;
extern void ux500_cpu_die(unsigned int cpu);

#endif /* __ASM_ARCH_SETUP_H */


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