Re: [PATCH 1/8] ARM: SCU: Add common routines for secondary CPUbootup

From: Russell King - ARM Linux
Date: Thu Dec 02 2010 - 13:02:30 EST

On Thu, Dec 02, 2010 at 05:38:24PM +0000, Russell King - ARM Linux wrote:
> What if a platform, for what ever reason, wants to have 3 CPUs,
> numbered 0, 2, 3 ? That's the reason why the code which sets the
> possible and present maps isn't in the ARM core code - Eg, we don't
> know if a platform wants to keep CPU 1 in AMP mode to run some
> special software on it.
>
> I don't think it's worth it because I think trying to considate this
> is going to cripple the code structure in the future.

I don't think this is particularly worth it either:

8e511800fe64114d00b6a22c6e37a510b208785e
arch/arm/include/asm/smp.h | 14 ++++++-
arch/arm/kernel/smp.c | 71 ++++++++++++++++++++++++++++++++------
arch/arm/kernel/smp_scu.c | 2 +-
arch/arm/mach-omap2/omap-smp.c | 67 +++---------------------------------
arch/arm/mach-realview/platsmp.c | 71 ++++---------------------------------
arch/arm/mach-s5pv310/platsmp.c | 63 ++++-----------------------------
arch/arm/mach-tegra/platsmp.c | 39 ++-------------------
arch/arm/mach-ux500/platsmp.c | 55 +++--------------------------
arch/arm/mach-vexpress/platsmp.c | 69 +++++-------------------------------
9 files changed, 113 insertions(+), 338 deletions(-)

diff --git a/arch/arm/include/asm/smp.h b/arch/arm/include/asm/smp.h
index f93d0a6..99dd48b 100644
--- a/arch/arm/include/asm/smp.h
+++ b/arch/arm/include/asm/smp.h
@@ -46,9 +46,14 @@ asmlinkage void do_IPI(int ipinr, struct pt_regs *regs);
extern void smp_init_cpus(void);

/*
- * Move global data into per-processor storage.
+ * Initialize cpu_possible map for 0 .. CPUs.
*/
-extern void smp_store_cpu_info(unsigned int cpuid);
+void smp_init_cpu_possible(unsigned int);
+
+/*
+ * Initialize cpu_present map for 0 .. CPUs.
+ */
+void smp_init_cpu_present(unsigned int);

/*
* Raise an IPI cross call on CPUs in callmap.
@@ -73,6 +78,11 @@ asmlinkage void secondary_start_kernel(void);
extern void platform_secondary_init(unsigned int cpu);

/*
+ * Initialize cpu_possible map, and enable coherency
+ */
+extern void platform_smp_prepare_cpus(unsigned int);
+
+/*
* Initial data for bringing up a secondary CPU.
*/
struct secondary_data {
diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c
index 4c3ed4f..46af08f 100644
--- a/arch/arm/kernel/smp.c
+++ b/arch/arm/kernel/smp.c
@@ -296,6 +296,17 @@ void __ref cpu_die(void)
#endif /* CONFIG_HOTPLUG_CPU */

/*
+ * Called by both boot and secondaries to move global data into
+ * per-processor storage.
+ */
+static void __cpuinit smp_store_cpu_info(unsigned int cpuid)
+{
+ struct cpuinfo_arm *cpu_info = &per_cpu(cpu_data, cpuid);
+
+ cpu_info->loops_per_jiffy = loops_per_jiffy;
+}
+
+/*
* This is the secondary CPU boot entry. We're using this CPUs
* idle thread stack, but a set of temporary page tables.
*/
@@ -353,17 +364,6 @@ asmlinkage void __cpuinit secondary_start_kernel(void)
cpu_idle();
}

-/*
- * Called by both boot and secondaries to move global data into
- * per-processor storage.
- */
-void __cpuinit smp_store_cpu_info(unsigned int cpuid)
-{
- struct cpuinfo_arm *cpu_info = &per_cpu(cpu_data, cpuid);
-
- cpu_info->loops_per_jiffy = loops_per_jiffy;
-}
-
void __init smp_cpus_done(unsigned int max_cpus)
{
int cpu;
@@ -386,6 +386,55 @@ void __init smp_prepare_boot_cpu(void)
per_cpu(cpu_data, cpu).idle = current;
}

+void __init smp_init_cpu_possible(unsigned int ncores)
+{
+ unsigned int i;
+
+ if (ncores > NR_CPUS) {
+ pr_warning("SMP: no. of cores (%u) greater than configured maximum of %u - clipping\n",
+ ncores, NR_CPUS);
+ ncores = NR_CPUS;
+ }
+
+ for (i = 0; i < ncores; i++)
+ set_cpu_possible(i, true);
+}
+
+void __init smp_init_cpu_present(unsigned int ncores)
+{
+ unsigned int i;
+
+ for (i = 0; i < ncores; i++)
+ set_cpu_present(i, true);
+}
+
+void __init smp_prepare_cpus(unsigned int max_cpus)
+{
+ unsigned int ncores = num_possible_cpus();
+
+ smp_store_cpu_info(smp_processor_id());
+
+ /*
+ * are we trying to boot more cores than exist?
+ */
+ if (max_cpus > ncores)
+ max_cpus = ncores;
+
+ if (max_cpus > 1) {
+ /*
+ * Enable the local timer or broadcast device for the
+ * boot CPU, but only if we have more than one CPU.
+ */
+ percpu_timer_setup();
+
+ /*
+ * Initialise the SCU if there are more than one CPU
+ * and let them know where to start.
+ */
+ platform_smp_prepare_cpus(max_cpus);
+ }
+}
+
static void send_ipi_message(const struct cpumask *mask, enum ipi_msg_type msg)
{
unsigned long flags;
diff --git a/arch/arm/kernel/smp_scu.c b/arch/arm/kernel/smp_scu.c
index 9ab4149..904b77b 100644
--- a/arch/arm/kernel/smp_scu.c
+++ b/arch/arm/kernel/smp_scu.c
@@ -11,8 +11,8 @@
#include <linux/init.h>
#include <linux/io.h>

-#include <asm/smp_scu.h>
#include <asm/cacheflush.h>
+#include <asm/smp_scu.h>

#define SCU_CTRL 0x00
#define SCU_CONFIG 0x04
diff --git a/arch/arm/mach-omap2/omap-smp.c b/arch/arm/mach-omap2/omap-smp.c
index 56a8bce..a123edf 100644
--- a/arch/arm/mach-omap2/omap-smp.c
+++ b/arch/arm/mach-omap2/omap-smp.c
@@ -21,7 +21,6 @@
#include <linux/io.h>

#include <asm/cacheflush.h>
-#include <asm/localtimer.h>
#include <asm/smp_scu.h>
#include <mach/hardware.h>
#include <mach/omap4-common.h>
@@ -29,16 +28,6 @@
/* SCU base address */
static void __iomem *scu_base;

-/*
- * Use SCU config register to count number of cores
- */
-static inline unsigned int get_core_count(void)
-{
- if (scu_base)
- return scu_get_core_count(scu_base);
- return 1;
-}
-
static DEFINE_SPINLOCK(boot_lock);

void __cpuinit platform_secondary_init(unsigned int cpu)
@@ -112,65 +101,19 @@ static void __init wakeup_secondary(void)
*/
void __init smp_init_cpus(void)
{
- unsigned int i, ncores;
-
/* Never released */
scu_base = ioremap(OMAP44XX_SCU_BASE, SZ_256);
BUG_ON(!scu_base);

- ncores = get_core_count();
-
- for (i = 0; i < ncores; i++)
- set_cpu_possible(i, true);
+ smp_init_cpu_possible(scu_get_core_count(scu_base));
}

-void __init smp_prepare_cpus(unsigned int max_cpus)
+void __init platform_smp_prepare_cpus(unsigned int max_cpus)
{
- unsigned int ncores = get_core_count();
- unsigned int cpu = smp_processor_id();
- int i;
-
- /* sanity check */
- if (ncores == 0) {
- printk(KERN_ERR
- "OMAP4: strange core count of 0? Default to 1\n");
- ncores = 1;
- }
-
- if (ncores > NR_CPUS) {
- printk(KERN_WARNING
- "OMAP4: no. of cores (%d) greater than configured "
- "maximum of %d - clipping\n",
- ncores, NR_CPUS);
- ncores = NR_CPUS;
- }
- smp_store_cpu_info(cpu);
-
- /*
- * are we trying to boot more cores than exist?
- */
- if (max_cpus > ncores)
- max_cpus = ncores;
+ smp_init_cpu_present(max_cpus);

/*
- * Initialise the present map, which describes the set of CPUs
- * actually populated at the present time.
+ * Wake up the secondary core using wakeup_secondary().
*/
- for (i = 0; i < max_cpus; i++)
- set_cpu_present(i, true);
-
- if (max_cpus > 1) {
- /*
- * Enable the local timer or broadcast device for the
- * boot CPU, but only if we have more than one CPU.
- */
- percpu_timer_setup();
-
- /*
- * Initialise the SCU and wake up the secondary core using
- * wakeup_secondary().
- */
- scu_enable(scu_base);
- wakeup_secondary();
- }
+ wakeup_secondary();
}
diff --git a/arch/arm/mach-realview/platsmp.c b/arch/arm/mach-realview/platsmp.c
index af3d909..b9908e4 100644
--- a/arch/arm/mach-realview/platsmp.c
+++ b/arch/arm/mach-realview/platsmp.c
@@ -19,7 +19,6 @@
#include <asm/cacheflush.h>
#include <mach/hardware.h>
#include <asm/mach-types.h>
-#include <asm/localtimer.h>
#include <asm/unified.h>

#include <mach/board-eb.h>
@@ -50,14 +49,6 @@ static void __iomem *scu_base_addr(void)
return (void __iomem *)0;
}

-static inline unsigned int get_core_count(void)
-{
- void __iomem *scu_base = scu_base_addr();
- if (scu_base)
- return scu_get_core_count(scu_base);
- return 1;
-}
-
static DEFINE_SPINLOCK(boot_lock);

void __cpuinit platform_secondary_init(unsigned int cpu)
@@ -158,64 +149,18 @@ static void __init poke_milo(void)
*/
void __init smp_init_cpus(void)
{
- unsigned int i, ncores = get_core_count();
+ void __iomem *scu_base = scu_base_addr();
+ unsigned int ncores;
+
+ ncores = scu_base ? scu_get_core_count(scu_base) : 1;

- for (i = 0; i < ncores; i++)
- set_cpu_possible(i, true);
+ smp_init_cpu_possible(ncores);
}

-void __init smp_prepare_cpus(unsigned int max_cpus)
+void __init platform_smp_prepare_cpus(unsigned int max_cpus)
{
- unsigned int ncores = get_core_count();
- unsigned int cpu = smp_processor_id();
- int i;
-
- /* sanity check */
- if (ncores == 0) {
- printk(KERN_ERR
- "Realview: strange CM count of 0? Default to 1\n");
-
- ncores = 1;
- }
-
- if (ncores > NR_CPUS) {
- printk(KERN_WARNING
- "Realview: no. of cores (%d) greater than configured "
- "maximum of %d - clipping\n",
- ncores, NR_CPUS);
- ncores = NR_CPUS;
- }
+ smp_init_cpu_present(max_cpus);

- smp_store_cpu_info(cpu);
-
- /*
- * are we trying to boot more cores than exist?
- */
- if (max_cpus > ncores)
- max_cpus = ncores;
-
- /*
- * Initialise the present map, which describes the set of CPUs
- * actually populated at the present time.
- */
- for (i = 0; i < max_cpus; i++)
- set_cpu_present(i, true);
-
- /*
- * Initialise the SCU if there are more than one CPU and let
- * them know where to start. Note that, on modern versions of
- * MILO, the "poke" doesn't actually do anything until each
- * individual core is sent a soft interrupt to get it out of
- * WFI
- */
- if (max_cpus > 1) {
- /*
- * Enable the local timer or broadcast device for the
- * boot CPU, but only if we have more than one CPU.
- */
- percpu_timer_setup();
-
- scu_enable(scu_base_addr());
+ if (num_present_cpus() > 1)
poke_milo();
- }
}
diff --git a/arch/arm/mach-s5pv310/platsmp.c b/arch/arm/mach-s5pv310/platsmp.c
index d474426..407c825 100644
--- a/arch/arm/mach-s5pv310/platsmp.c
+++ b/arch/arm/mach-s5pv310/platsmp.c
@@ -22,7 +22,6 @@
#include <linux/io.h>

#include <asm/cacheflush.h>
-#include <asm/localtimer.h>
#include <asm/smp_scu.h>
#include <asm/unified.h>

@@ -125,68 +124,22 @@ int __cpuinit boot_secondary(unsigned int cpu, struct task_struct *idle)
void __init smp_init_cpus(void)
{
void __iomem *scu_base = scu_base_addr();
- unsigned int i, ncores;
+ unsigned int ncores;

ncores = scu_base ? scu_get_core_count(scu_base) : 1;

- /* sanity check */
- if (ncores == 0) {
- printk(KERN_ERR
- "S5PV310: strange CM count of 0? Default to 1\n");
-
- ncores = 1;
- }
-
- if (ncores > NR_CPUS) {
- printk(KERN_WARNING
- "S5PV310: no. of cores (%d) greater than configured "
- "maximum of %d - clipping\n",
- ncores, NR_CPUS);
- ncores = NR_CPUS;
- }
-
- for (i = 0; i < ncores; i++)
- set_cpu_possible(i, true);
+ smp_init_cpu_possible(ncores);
}

-void __init smp_prepare_cpus(unsigned int max_cpus)
+void __init platform_smp_prepare_cpus(unsigned int max_cpus)
{
- unsigned int ncores = num_possible_cpus();
- unsigned int cpu = smp_processor_id();
- int i;
-
- smp_store_cpu_info(cpu);
-
- /* are we trying to boot more cores than exist? */
- if (max_cpus > ncores)
- max_cpus = ncores;
+ smp_init_cpu_present(max_cpus);

/*
- * Initialise the present map, which describes the set of CPUs
- * actually populated at the present time.
+ * Write the address of secondary startup into the
+ * system-wide flags register. The boot monitor waits
+ * until it receives a soft interrupt, and then the
+ * secondary CPU branches to this address.
*/
- for (i = 0; i < max_cpus; i++)
- set_cpu_present(i, true);
-
- /*
- * Initialise the SCU if there are more than one CPU and let
- * them know where to start.
- */
- if (max_cpus > 1) {
- /*
- * Enable the local timer or broadcast device for the
- * boot CPU, but only if we have more than one CPU.
- */
- percpu_timer_setup();
-
- scu_enable(scu_base_addr());
-
- /*
- * Write the address of secondary startup into the
- * system-wide flags register. The boot monitor waits
- * until it receives a soft interrupt, and then the
- * secondary CPU branches to this address.
- */
__raw_writel(BSYM(virt_to_phys(s5pv310_secondary_startup)), S5P_VA_SYSRAM);
- }
}
diff --git a/arch/arm/mach-tegra/platsmp.c b/arch/arm/mach-tegra/platsmp.c
index 1c0fd92..abbb97b 100644
--- a/arch/arm/mach-tegra/platsmp.c
+++ b/arch/arm/mach-tegra/platsmp.c
@@ -22,7 +22,6 @@
#include <asm/cacheflush.h>
#include <mach/hardware.h>
#include <asm/mach-types.h>
-#include <asm/localtimer.h>
#include <asm/smp_scu.h>

#include <mach/iomap.h>
@@ -115,42 +114,10 @@ int __cpuinit boot_secondary(unsigned int cpu, struct task_struct *idle)
*/
void __init smp_init_cpus(void)
{
- unsigned int i, ncores = scu_get_core_count(scu_base);
-
- for (i = 0; i < ncores; i++)
- cpu_set(i, cpu_possible_map);
+ smp_init_cpu_possible(scu_get_core_count(scu_base));
}

-void __init smp_prepare_cpus(unsigned int max_cpus)
+void __init platform_smp_prepare_cpus(unsigned int max_cpus)
{
- unsigned int ncores = scu_get_core_count(scu_base);
- unsigned int cpu = smp_processor_id();
- int i;
-
- smp_store_cpu_info(cpu);
-
- /*
- * are we trying to boot more cores than exist?
- */
- if (max_cpus > ncores)
- max_cpus = ncores;
-
- /*
- * Initialise the present map, which describes the set of CPUs
- * actually populated at the present time.
- */
- for (i = 0; i < max_cpus; i++)
- set_cpu_present(i, true);
-
- /*
- * Initialise the SCU if there are more than one CPU and let
- * them know where to start. Note that, on modern versions of
- * MILO, the "poke" doesn't actually do anything until each
- * individual core is sent a soft interrupt to get it out of
- * WFI
- */
- if (max_cpus > 1) {
- percpu_timer_setup();
- scu_enable(scu_base);
- }
+ smp_init_cpu_present(max_cpus);
}
diff --git a/arch/arm/mach-ux500/platsmp.c b/arch/arm/mach-ux500/platsmp.c
index b8987bd..e03a5d0 100644
--- a/arch/arm/mach-ux500/platsmp.c
+++ b/arch/arm/mach-ux500/platsmp.c
@@ -18,7 +18,6 @@
#include <linux/io.h>

#include <asm/cacheflush.h>
-#include <asm/localtimer.h>
#include <asm/smp_scu.h>
#include <mach/hardware.h>

@@ -28,11 +27,6 @@
*/
volatile int __cpuinitdata pen_release = -1;

-static unsigned int __init get_core_count(void)
-{
- return scu_get_core_count(__io_address(UX500_SCU_BASE));
-}
-
static DEFINE_SPINLOCK(boot_lock);

void __cpuinit platform_secondary_init(unsigned int cpu)
@@ -126,55 +120,18 @@ static void __init wakeup_secondary(void)
*/
void __init smp_init_cpus(void)
{
- unsigned int i, ncores = get_core_count();
+ unsigned int ncores = scu_get_core_count(__io_address(UX500_SCU_BASE));

- for (i = 0; i < ncores; i++)
- set_cpu_possible(i, true);
+ smp_init_cpu_possible(ncores);
}

void __init smp_prepare_cpus(unsigned int max_cpus)
{
- unsigned int ncores = get_core_count();
- unsigned int cpu = smp_processor_id();
- int i;
-
- /* sanity check */
- if (ncores == 0) {
- printk(KERN_ERR
- "U8500: strange CM count of 0? Default to 1\n");
- ncores = 1;
- }
-
- if (ncores > num_possible_cpus()) {
- printk(KERN_WARNING
- "U8500: no. of cores (%d) greater than configured "
- "maximum of %d - clipping\n",
- ncores, num_possible_cpus());
- ncores = num_possible_cpus();
- }
-
- smp_store_cpu_info(cpu);
+ smp_init_cpu_present(max_cpus);

/*
- * are we trying to boot more cores than exist?
+ * Enable the local timer or broadcast device for the
+ * boot CPU, but only if we have more than one CPU.
*/
- if (max_cpus > ncores)
- max_cpus = ncores;
-
- /*
- * Initialise the present map, which describes the set of CPUs
- * actually populated at the present time.
- */
- for (i = 0; i < max_cpus; i++)
- set_cpu_present(i, true);
-
- if (max_cpus > 1) {
- /*
- * Enable the local timer or broadcast device for the
- * boot CPU, but only if we have more than one CPU.
- */
- percpu_timer_setup();
- scu_enable(__io_address(UX500_SCU_BASE));
- wakeup_secondary();
- }
+ wakeup_secondary();
}
diff --git a/arch/arm/mach-vexpress/platsmp.c b/arch/arm/mach-vexpress/platsmp.c
index 276f916..92ef7cb 100644
--- a/arch/arm/mach-vexpress/platsmp.c
+++ b/arch/arm/mach-vexpress/platsmp.c
@@ -17,7 +17,6 @@
#include <linux/io.h>

#include <asm/cacheflush.h>
-#include <asm/localtimer.h>
#include <asm/smp_scu.h>
#include <asm/unified.h>

@@ -119,72 +118,24 @@ int __cpuinit boot_secondary(unsigned int cpu, struct task_struct *idle)
void __init smp_init_cpus(void)
{
void __iomem *scu_base = scu_base_addr();
- unsigned int i, ncores;
+ unsigned int ncores;

ncores = scu_base ? scu_get_core_count(scu_base) : 1;

- /* sanity check */
- if (ncores == 0) {
- printk(KERN_ERR
- "vexpress: strange CM count of 0? Default to 1\n");
-
- ncores = 1;
- }
-
- if (ncores > NR_CPUS) {
- printk(KERN_WARNING
- "vexpress: no. of cores (%d) greater than configured "
- "maximum of %d - clipping\n",
- ncores, NR_CPUS);
- ncores = NR_CPUS;
- }
-
- for (i = 0; i < ncores; i++)
- set_cpu_possible(i, true);
+ smp_init_cpu_possible(ncores);
}

void __init smp_prepare_cpus(unsigned int max_cpus)
{
- unsigned int ncores = num_possible_cpus();
- unsigned int cpu = smp_processor_id();
- int i;
-
- smp_store_cpu_info(cpu);
+ smp_init_cpu_present(max_cpus);

/*
- * are we trying to boot more cores than exist?
+ * Write the address of secondary startup into the
+ * system-wide flags register. The boot monitor waits
+ * until it receives a soft interrupt, and then the
+ * secondary CPU branches to this address.
*/
- if (max_cpus > ncores)
- max_cpus = ncores;
-
- /*
- * Initialise the present map, which describes the set of CPUs
- * actually populated at the present time.
- */
- for (i = 0; i < max_cpus; i++)
- set_cpu_present(i, true);
-
- /*
- * Initialise the SCU if there are more than one CPU and let
- * them know where to start.
- */
- if (max_cpus > 1) {
- /*
- * Enable the local timer or broadcast device for the
- * boot CPU, but only if we have more than one CPU.
- */
- percpu_timer_setup();
-
- scu_enable(scu_base_addr());
-
- /*
- * Write the address of secondary startup into the
- * system-wide flags register. The boot monitor waits
- * until it receives a soft interrupt, and then the
- * secondary CPU branches to this address.
- */
- writel(~0, MMIO_P2V(V2M_SYS_FLAGSCLR));
- writel(BSYM(virt_to_phys(vexpress_secondary_startup)),
- MMIO_P2V(V2M_SYS_FLAGSSET));
- }
+ writel(~0, MMIO_P2V(V2M_SYS_FLAGSCLR));
+ writel(BSYM(virt_to_phys(vexpress_secondary_startup)),
+ MMIO_P2V(V2M_SYS_FLAGSSET));
}

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