On Thu, May 07, 2009 at 12:59:24PM +0530, Santosh Shilimkar wrote:
> +/*
> + * OMAP4 specific entry point for secondary CPU to jump from ROM
> + * code. This routine also provides a holding flag into which
> + * secondary core is held until we're ready for it to initialise.
> + * The primary core will update the this flag using a hardware
> + * register AuxCoreBoot1.
However, it's actually using the 'cpu_release' variable rather than
the AuxCoreBoot1 register. Maybe the comment needs updating, or the
code needs fixing?
> + */
> +ENTRY(omap_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
> +hold: ldr r7, [r6] @ read from AuxCoreBoot1
> + cmp r7, r0
> + bne hold
> +
> + /*
> + * we've been released from the holding pen: secondary_stack
> + * should now contain the SVC stack for this core
> + */
> + b secondary_startup
> +
> +1: .long .
> + .long cpu_release
> +
> diff --git a/arch/arm/mach-omap2/omap-smp.c b/arch/arm/mach-omap2/omap-smp.c
> new file mode 100644
> index 0000000..1d18acb
> --- /dev/null
> +++ b/arch/arm/mach-omap2/omap-smp.c
> @@ -0,0 +1,238 @@
> +/*
> + * OMAP4 SMP source file. It contains platform specific fucntions
> + * needed for the linux smp kernel.
> + *
> + * Copyright (C) 2009 Texas Instruments, Inc.
> + *
> + * Author:
> + * Santosh Shilimkar <[email protected]>
> + *
> + * Platform file needed for the OMAP4 SMP. This file is based on arm
> + * realview smp platform.
> + * * Copyright (c) 2002 ARM Limited.
> + *
> + * 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/init.h>
> +#include <linux/errno.h>
> +#include <linux/delay.h>
> +#include <linux/device.h>
> +#include <linux/jiffies.h>
> +#include <linux/smp.h>
> +#include <linux/io.h>
> +
> +#include <asm/cacheflush.h>
> +#include <mach/scu.h>
> +#include <mach/hardware.h>
> +#include <asm/mach-types.h>
> +
> +/* Registers used for communicating startup information */
> +#define OMAP4_AUXCOREBOOT_REG0 (OMAP44XX_VA_WKUPGEN_BASE +
> 0x800)
> +#define OMAP4_AUXCOREBOOT_REG1 (OMAP44XX_VA_WKUPGEN_BASE +
> 0x804)
> +
> +/* FIXME: Move to a common header file */
> +extern void omap_secondary_startup(void);
> +
> +/*
> + * Control for which core is the next to come out of the secondary
> + * boot "Auxcontrol_register"
> + */
> +int __cpuinitdata cpu_release = -1;
> +
> +/*
> + * Setup the SCU
> + */
> +static void scu_enable(void)
> +{
> + u32 scu_ctrl;
> + void __iomem *scu_base = OMAP44XX_VA_SCU_BASE;
> +
> + scu_ctrl = __raw_readl(scu_base + SCU_CTRL);
> + scu_ctrl |= 1;
> + __raw_writel(scu_ctrl, scu_base + SCU_CTRL);
> +}
> +
> +/*
> + * Use SCU config register to count number of cores
> + */
> +static unsigned int __init get_core_count(void)
> +{
> + unsigned int ncores;
> + void __iomem *scu_base = OMAP44XX_VA_SCU_BASE;
> +
> + if (scu_base) {
> + ncores = __raw_readl(scu_base + SCU_CONFIG);
> + ncores = (ncores & 0x03) + 1;
> + } else {
> + ncores = 1;
Too many tabs.
> + }
> +
> + return ncores;
> +}
> +
> +static DEFINE_SPINLOCK(boot_lock);
> +
> +void __cpuinit platform_secondary_init(unsigned int cpu)
> +{
> + trace_hardirqs_off();
> +
> + /*
> + * If any interrupts are already enabled for the primary
> + * core (e.g. timer irq), then they will not have been enabled
> + * for us: do so
> + */
> +
> + gic_cpu_init(0, IO_ADDRESS(OMAP44XX_GIC_CPU_BASE));
> +
> + /*
> + * Let the primary processor know we're out of the
> + * pen, then head off into the C entry point
> + */
> + cpu_release = -1;
> + smp_wmb();
> +
> + /*
> + * Synchronise with the boot thread.
> + */
> + spin_lock(&boot_lock);
> + spin_unlock(&boot_lock);
> +}
> +
> +int __cpuinit boot_secondary(unsigned int cpu, struct task_struct *idle)
> +{
> + unsigned long timeout;
> +
> + /*
> + * Set synchronisation state between this boot processor
> + * and the secondary one
> + */
> + spin_lock(&boot_lock);
> +
> + /*
> + * The secondary processor is waiting for an event to come out of
> + * wfe. Release it, then wait for it to flag that it has been
> + * released by resetting cpu_release.
> + *
> + * Singal the ROM code that the secondary core can be released
> + */
> + cpu_release = cpu;
> + __raw_writel(cpu, OMAP4_AUXCOREBOOT_REG1);
> + flush_cache_all();
> + /*
> + * Send a 'sev' to wake the secondary core again because
> + * ROM code will put core in WFE till the cpu_release
> + * flag is set.
Not sure this comment is accurate. Surely the ROM code doesn't know
about our own cpu_release flag.
> + */
> + set_event();
> + mb();
> +
> + timeout = jiffies + (1 * HZ);
> + while (time_before(jiffies, timeout)) {
> + smp_rmb();
> + if (cpu_release == -1)
> + break;
> +
> + udelay(10);
> + }
> +
> + /*
> + * Now the secondary core is starting up let it run its
> + * calibrations, then wait for it to finish
> + */
> + spin_unlock(&boot_lock);
> +
> + return cpu_release != -1 ? -ENOSYS : 0;
> +}
> +
> +static void __init wakeup_secondary(void)
> +{
> +
> + /* cpu is not to be released from the hold yet */
> + cpu_release = -1;
> +
> + /*
> + * write the address of secondary startup into the system-wide
> + * AuxCoreBoot0 where ROM code will jump and start executing
> + * on secondary core
> + */
> + __raw_writel(virt_to_phys(omap_secondary_startup), \
> + OMAP4_AUXCOREBOOT_REG0);
> + /*
> + * Send a 'sev' to wake the secondary core from WFE.
> + */
> + set_event();
> + mb();
> +}
> +
> +/*
> + * Initialise the CPU possible map early - this describes the CPUs
> + * which may be present or become present in the system.
> + */
> +void __init smp_init_cpus(void)
> +{
> + unsigned int i, ncores = get_core_count();
> +
> + for (i = 0; i < ncores; i++)
> + cpu_set(i, cpu_possible_map);
> +}
> +
> +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
> + "OMAP4: strange core count of 0? Default to 1\n");
> + ncores = 1;
> + }
> +
> + if (ncores > num_possible_cpus()) {
> + printk(KERN_WARNING
> + "OMAP4: 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);
> +
> + /*
> + * are we trying to boot more cores than exist?
> + */
> + if (max_cpus > ncores)
> + max_cpus = ncores;
> +
> +#ifdef CONFIG_LOCAL_TIMERS
> + /*
> + * Enable the local timer for primary CPU. If the device is
> + * dummy (!CONFIG_LOCAL_TIMERS), it was already registers in
> + * omap_timer_init
> + */
> + local_timer_setup();
> +#endif
> +
> + /*
> + * Initialise the present map, which describes the set of CPUs
> + * actually populated at the present time.
> + */
> + for (i = 0; i < max_cpus; i++)
> + cpu_set(i, cpu_present_map);
> +
> + /*
> + * Initialise the SCU and wake up the secondary core using
> + * wakeup_secondary().
> + */
> + if (max_cpus > 1) {
> + scu_enable();
> + /*
> + * Ensure that the data accessed by CPU0 before the SCU was
> + * initialised is visible to CPU1.
> + */
> + flush_cache_all();
> + wakeup_secondary();
> + }
> +}
> diff --git a/arch/arm/plat-omap/include/mach/scu.h
> b/arch/arm/plat-omap/include/mach/scu.h
> new file mode 100644
> index 0000000..2ee6660
> --- /dev/null
> +++ b/arch/arm/plat-omap/include/mach/scu.h
> @@ -0,0 +1,28 @@
> +/*
> + * SCU regsiter header.
> + *
> + * Copyright (C) 2009 Texas Instruments, Inc.
> + *
> + *
> + * Author:
> + * Santosh Shilimkar <[email protected]>
> + *
> + * Snoop Control Unit Registers. This file is based on arm
> + * realview smp platform.
> + * Copyright (c) 2003 ARM Limited.
> + *
> + * 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.
> + */
> +#ifndef __OMAP_ARCH_SCU_H
> +#define __OMAP_ARCH_SCU_H
> +/*
> + * SCU registers
> + */
> +#define SCU_CTRL 0x00
> +#define SCU_CONFIG 0x04
> +#define SCU_CPU_STATUS 0x08
> +#define SCU_INVALIDATE 0x0c
> +
> +#endif
> diff --git a/arch/arm/plat-omap/include/mach/smp.h
> b/arch/arm/plat-omap/include/mach/smp.h
> new file mode 100644
> index 0000000..b6a3e67
> --- /dev/null
> +++ b/arch/arm/plat-omap/include/mach/smp.h
> @@ -0,0 +1,56 @@
> +/*
> + * OMAP4 machine specific smp.h
> + *
> + * Copyright (C) 2009 Texas Instruments, Inc.
> + *
> + * Author:
> + * Santosh Shilimkar <[email protected]>
> + *
> + * Interface functions needed for the SMP. This file is based on arm
> + * realview smp platform.
> + * Copyright (c) 2003 ARM Limited.
> + *
> + * 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.
> + */
> +#ifndef OMAP_ARCH_SMP_H
> +#define OMAP_ARCH_SMP_H
> +
> +
> +#include <asm/hardware/gic.h>
> +
> +/*
> + * set_event() is used to wake up secondary core from wfe using sev. ROM
> + * code puts the second core into wfe(standby).
> + *
> + */
> + #define set_event() __asm__ __volatile__ ("sev" : : : "memory")
> +
> +/*
> + * We use Soft IRQ1 as the IPI
> + */
> +static inline void smp_cross_call(cpumask_t callmap)
> +{
> + gic_raise_softirq(callmap, 1);
> +}
> +
> +/*
> + * Can be useful for WFI boot strategy.
> + */
> +static inline void smp_cross_call_done(cpumask_t callmap)
> +{
> +}
> +
> +/*
> + * Read MPIDR: Multiprocessor affinity register
> + */
> +#define hard_smp_processor_id() \
> + ({ \
> + unsigned int cpunum; \
> + __asm__("mrc p15, 0, %0, c0, c0, 5" \
> + : "=r" (cpunum)); \
> + cpunum &= 0x0F; \
> + })
> +
> +#endif
> --
> 1.5.4.7
>
>
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