Re: [PATCH v3 5/8] ARM: mediatek: add smp bringup code for MT6580

[Scott Shu]

On Wed, 2015-08-05 at 18:47 +0200, Matthias Brugger wrote:
> On Tuesday, August 04, 2015 09:54:21 PM Scott Shu wrote:
> > Add support for cpu enable-method "mediatek,mt6580-smp" for booting
> > secondary CPUs on MT6580.
> > 
> > Signed-off-by: Scott Shu <scott.shu@xxxxxxxxxxxx>
> > ---
> >  arch/arm/mach-mediatek/platsmp.c |  137
> > ++++++++++++++++++++++++++++++++++++++ 1 file changed, 137 insertions(+)
> > 
> > diff --git a/arch/arm/mach-mediatek/platsmp.c
> > b/arch/arm/mach-mediatek/platsmp.c index a5bc108..94f7865 100644
> > --- a/arch/arm/mach-mediatek/platsmp.c
> > +++ b/arch/arm/mach-mediatek/platsmp.c
> > @@ -21,10 +21,16 @@
> >  #include <linux/of_address.h>
> >  #include <linux/string.h>
> >  #include <linux/threads.h>
> > +#include <linux/delay.h>
> > +#include <asm/cacheflush.h>
> > +
> > +#include <linux/soc/mediatek/scpsys.h>
> > 
> >  #define MTK_MAX_CPU		8
> >  #define MTK_SMP_REG_SIZE	0x1000
> > 
> > +static DEFINE_SPINLOCK(boot_lock);
> > +
> >  struct mtk_smp_boot_info {
> >  	unsigned long smp_base;
> >  	unsigned int jump_reg;
> > @@ -56,6 +62,126 @@ static const struct of_device_id mtk_smp_boot_infos[]
> > __initconst = { static void __iomem *mtk_smp_base;
> >  static const struct mtk_smp_boot_info *mtk_smp_info;
> > 
> > +#ifdef CONFIG_HOTPLUG_CPU
> > +static int mt6580_cpu_kill(unsigned cpu)
> > +{
> > +	int ret;
> > +
> > +	ret = spm_cpu_mtcmos_off(cpu, 1);
> 
> is this function ever called with wfi == 0?

Yes, wfi == 0 at MT6582 "special" dual-core platform, but for MT6580,
wfi is always 1.

> > +	if (ret < 0)
> > +		return 0;
> > +
> > +	return 1;
> > +}
> > +
> > +static void mt6580_cpu_die(unsigned int cpu)
> > +{
> > +	for (;;)
> > +		cpu_do_idle();
> > +}
> > +#endif
> > +
> > +static void write_pen_release(int val)
> > +{
> > +	pen_release = val;
> > +	/* Make sure this is visible to other CPUs */
> > +	smp_wmb();
> > +	sync_cache_w(&pen_release);
> > +}
> > +
> > +/*
> > + * Refer common "pen" secondary release method
> > + */
> > +static int mt6580_boot_secondary(unsigned int cpu, struct task_struct
> > *idle) +{
> > +	unsigned long timeout;
> > +	int ret;
> > +
> > +	/*
> > +	 * 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.
> > +	 *
> > +	 * Note that "pen_release" is the hardware CPU ID, whereas
> > +	 * "cpu" is Linux's internal ID.
> > +	 */
> > +	write_pen_release(cpu);
> > +
> > +	/*
> > +	 * CPU power on control by SPM
> > +	 */
> > +	ret = spm_cpu_mtcmos_on(cpu);
> > +	if (ret < 0) {
> > +		spin_unlock(&boot_lock);
> > +		return -ENXIO;
> > +	}
> > +
> > +	timeout = jiffies + (1 * HZ);
> > +	while (time_before(jiffies, timeout)) {
> > +		/* Read barrier */
> > +		smp_rmb();
> > +
> > +		if (pen_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 (pen_release != -1 ? -ENXIO : 0);
> > +}
> > +
> > +static void mt6580_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);
> > +}
> > +
> > +#define MT6580_INFRACFG_AO	0x10001000
> > +#define SW_ROM_PD		BIT(31)
> 
> Please put the defines on the beginning of the file.
> SW_ROM_PD bit is the same on other SoCs? I wasn't able to reveal that from the 
> data sheets. If this is MT6580 only, the define should be renamed.
> 

OK, fixed in next version. 

> > +
> > +static void __init mt6580_smp_prepare_cpus(unsigned int max_cpus)
> > +{
> > +	static void __iomem *infracfg_ao_base;
> > +
> > +	infracfg_ao_base = ioremap(MT6580_INFRACFG_AO, 0x1000);
> > +	if (!infracfg_ao_base) {
> > +		pr_err("%s: Unable to map I/O memory\n", __func__);
> > +		return;
> > +	}
> > +
> > +	/* Enable bootrom power down mode */
> > +	writel_relaxed(readl(infracfg_ao_base + 0x804) | SW_ROM_PD,
> > +		       infracfg_ao_base + 0x804);
> 
> Please use a define for the offset.
> I prefer to not cascade reads and writes but to use a temporary variable. But 
> if this is fine with the kernel coding style (I doubt, but I'm not sure) then 
> this is fine.
> 

OK, fixed in next version. 

Thanks,
Scott
> > +
> > +	/* Write the address of slave startup into boot address
> > +	   register for bootrom power down mode */
> > +	writel_relaxed(virt_to_phys(secondary_startup_arm),
> > +		       infracfg_ao_base + 0x800);
> > +
> > +	iounmap(infracfg_ao_base);
> > +}
> > +
> >  static int mtk_boot_secondary(unsigned int cpu, struct task_struct *idle)
> >  {
> >  	if (!mtk_smp_base)
> > @@ -142,3 +268,14 @@ static struct smp_operations mt6589_smp_ops __initdata
> > = { .smp_boot_secondary = mtk_boot_secondary,
> >  };
> >  CPU_METHOD_OF_DECLARE(mt6589_smp, "mediatek,mt6589-smp", &mt6589_smp_ops);
> > +
> > +static struct smp_operations mt6580_smp_ops __initdata = {
> > +	.smp_prepare_cpus = mt6580_smp_prepare_cpus,
> > +	.smp_secondary_init = mt6580_secondary_init,
> > +	.smp_boot_secondary = mt6580_boot_secondary,
> > +#ifdef CONFIG_HOTPLUG_CPU
> > +	.cpu_kill = mt6580_cpu_kill,
> > +	.cpu_die = mt6580_cpu_die,
> > +#endif
> > +};
> > +CPU_METHOD_OF_DECLARE(mt6580_smp, "mediatek,mt6580-smp", &mt6580_smp_ops);
> 


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