Re: [PATCH v2 3/4] ARM: EXYNOS: add Exynos Dual Cluster Support

[Daniel Lezcano <daniel.lezcano@linaro.org>]

On 10/14/2013 05:08 PM, Vyacheslav Tyrtov wrote:
> From: Tarek Dakhran <t.dakhran@samsung.com>
>
> Add EDCS(Exynos Dual Cluster Support) for Samsung Exynos5410 SoC.
> This enables all 8 cores, 4 x A7 and 4 x A15 run at the same time.

IIUC, the 5410 has a CCI-400 bug preventing to use the two clusters at 
the same time. Right ? Could you explain how you fixed it ?

> Signed-off-by: Tarek Dakhran <t.dakhran@samsung.com>
> Signed-off-by: Vyacheslav Tyrtov <v.tyrtov@samsung.com>
> ---
>   arch/arm/mach-exynos/Makefile |   2 +
>   arch/arm/mach-exynos/edcs.c   | 270 ++++++++++++++++++++++++++++++++++++++++++
>   2 files changed, 272 insertions(+)
>   create mode 100644 arch/arm/mach-exynos/edcs.c
>
> diff --git a/arch/arm/mach-exynos/Makefile b/arch/arm/mach-exynos/Makefile
> index 5369615..ba6efdb 100644
> --- a/arch/arm/mach-exynos/Makefile
> +++ b/arch/arm/mach-exynos/Makefile
> @@ -34,3 +34,5 @@ AFLAGS_exynos-smc.o		:=-Wa,-march=armv7-a$(plus_sec)
>
>   obj-$(CONFIG_MACH_EXYNOS4_DT)		+= mach-exynos4-dt.o
>   obj-$(CONFIG_MACH_EXYNOS5_DT)		+= mach-exynos5-dt.o
> +
> +obj-$(CONFIG_SOC_EXYNOS5410)		+= edcs.o
> diff --git a/arch/arm/mach-exynos/edcs.c b/arch/arm/mach-exynos/edcs.c
> new file mode 100644
> index 0000000..e304bd9
> --- /dev/null
> +++ b/arch/arm/mach-exynos/edcs.c
> @@ -0,0 +1,270 @@
> +/*
> + * arch/arm/mach-exynos/edcs.c - exynos dual cluster power management support
> + *
> + * Copyright (c) 2013 Samsung Electronics Co., Ltd.
> + * Author: Tarek Dakhran <t.dakhran@samsung.com>
> + *
> + * 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.
> + *
> + * EDCS(exynos dual cluster support) for Exynos5410 SoC.
> + */
> +
> +#include <linux/init.h>
> +#include <linux/io.h>
> +#include <linux/of_address.h>
> +#include <linux/spinlock.h>
> +#include <linux/errno.h>
> +
> +#include <asm/mcpm.h>
> +#include <asm/proc-fns.h>
> +#include <asm/cacheflush.h>
> +#include <asm/cputype.h>
> +#include <asm/cp15.h>
> +
> +#include <linux/arm-cci.h>
> +#include <mach/regs-pmu.h>
> +
> +#define EDCS_CPUS_PER_CLUSTER	4
> +#define EDCS_CLUSTERS		2
> +
> +/* Exynos5410 power management registers */
> +#define EDCS_CORE_CONFIGURATION(_nr)	(S5P_ARM_CORE0_CONFIGURATION	\
> +						+ ((_nr) * 0x80))
> +#define EDCS_CORE_STATUS(_nr)		(EDCS_CORE_CONFIGURATION(_nr) + 0x4)
> +#define EDCS_CORE_OPTION(_nr)		(EDCS_CORE_CONFIGURATION(_nr) + 0x8)
> +
> +#define REG_CPU_STATE_ADDR0		(S5P_VA_SYSRAM_NS + 0x28)
> +#define REG_CPU_STATE_ADDR(_nr)		(REG_CPU_STATE_ADDR0 +	\
> +						 _nr * EDCS_CPUS_PER_CLUSTER)
> +
> +static arch_spinlock_t edcs_lock = __ARCH_SPIN_LOCK_UNLOCKED;
> +
> +static int edcs_use_count[EDCS_CPUS_PER_CLUSTER][EDCS_CLUSTERS];
> +static int core_count[EDCS_CLUSTERS];
> +
> +static void exynos_core_power_control(unsigned int cpu, unsigned int cluster,
> +				bool enable)
> +{
> +	unsigned int offset = cluster * EDCS_CPUS_PER_CLUSTER + cpu;
> +	int value = enable ? S5P_CORE_LOCAL_PWR_EN : 0;
> +
> +	if ((__raw_readl(EDCS_CORE_STATUS(offset)) & 0x3) != value)
> +		__raw_writel(value, EDCS_CORE_CONFIGURATION(offset));
> +}
> +
> +static void exynos_core_power_up(unsigned int cpu, unsigned int cluster)
> +{
> +	exynos_core_power_control(cpu, cluster, true);
> +}
> +
> +static void exynos_core_power_down(unsigned int cpu, unsigned int cluster)
> +{
> +	exynos_core_power_control(cpu, cluster, false);
> +}
> +
> +void set_boot_flag(unsigned int cpu, unsigned int mode)
> +{
> +	__raw_writel(mode, REG_CPU_STATE_ADDR(cpu));
> +}
> +
> +static int exynos_power_up(unsigned int cpu, unsigned int cluster)
> +{
> +	pr_debug("%s: cpu %u cluster %u\n", __func__, cpu, cluster);
> +	BUG_ON(cpu >= EDCS_CPUS_PER_CLUSTER || cluster >= EDCS_CLUSTERS);
> +
> +	local_irq_disable();
> +	arch_spin_lock(&edcs_lock);
> +
> +	edcs_use_count[cpu][cluster]++;
> +	if (edcs_use_count[cpu][cluster] == 1) {
> +		++core_count[cluster];
> +		set_boot_flag(cpu, 0x2);
> +		exynos_core_power_up(cpu, cluster);
> +	} else if (edcs_use_count[cpu][cluster] != 2) {
> +		/*
> +		 * The only possible values are:
> +		 * 0 = CPU down
> +		 * 1 = CPU (still) up
> +		 * 2 = CPU requested to be up before it had a chance
> +		 *     to actually make itself down.
> +		 * Any other value is a bug.
> +		 */
> +		BUG();
> +	}
> +
> +	arch_spin_unlock(&edcs_lock);
> +	local_irq_enable();
> +
> +	return 0;
> +}
> +static void exynos_power_down(void)
> +{
> +	unsigned int mpidr, cpu, cluster;
> +	bool last_man = false, skip_wfi = false;
> +
> +	mpidr = read_cpuid_mpidr();
> +	cpu = MPIDR_AFFINITY_LEVEL(mpidr, 0);
> +	cluster = MPIDR_AFFINITY_LEVEL(mpidr, 1);
> +
> +	pr_debug("%s: cpu %u cluster %u\n", __func__, cpu, cluster);
> +	BUG_ON(cpu >= EDCS_CPUS_PER_CLUSTER  || cluster >= EDCS_CLUSTERS);
> +
> +	__mcpm_cpu_going_down(cpu, cluster);
> +
> +	arch_spin_lock(&edcs_lock);
> +	BUG_ON(__mcpm_cluster_state(cluster) != CLUSTER_UP);
> +	edcs_use_count[cpu][cluster]--;
> +	if (edcs_use_count[cpu][cluster] == 0) {
> +		--core_count[cluster];
> +		if (core_count[cluster] == 0)
> +			last_man = true;
> +	} else if (edcs_use_count[cpu][cluster] == 1) {
> +		/*
> +		 * A power_up request went ahead of us.
> +		 * Even if we do not want to shut this CPU down,
> +		 * the caller expects a certain state as if the WFI
> +		 * was aborted.  So let's continue with cache cleaning.
> +		 */
> +		skip_wfi = true;
> +	} else
> +		BUG();
> +
> +	if (last_man && __mcpm_outbound_enter_critical(cpu, cluster)) {
> +		arch_spin_unlock(&edcs_lock);
> +
> +		if (read_cpuid_part_number() == ARM_CPU_PART_CORTEX_A15) {
> +			/*
> +			 * On the Cortex-A15 we need to disable
> +			 * L2 prefetching before flushing the cache.
> +			 */
> +			asm volatile(
> +			"mcr	p15, 1, %0, c15, c0, 3\n\t"
> +			"isb\n\t"
> +			"dsb"
> +			: : "r" (0x400));
> +		}
> +
> +		/*
> +		 * We need to disable and flush the whole (L1 and L2) cache.
> +		 * Let's do it in the safest possible way i.e. with
> +		 * no memory access within the following sequence
> +		 * including the stack.
> +		 *
> +		 * Note: fp is preserved to the stack explicitly prior doing
> +		 * this since adding it to the clobber list is incompatible
> +		 * with having CONFIG_FRAME_POINTER=y.
> +		 */
> +		asm volatile(
> +		"str	fp, [sp, #-4]!\n\t"
> +		"mrc	p15, 0, r0, c1, c0, 0	@ get CR\n\t"
> +		"bic	r0, r0, #"__stringify(CR_C)"\n\t"
> +		"mcr	p15, 0, r0, c1, c0, 0	@ set CR\n\t"
> +		"isb\n\t"
> +		"bl	v7_flush_dcache_all\n\t"
> +		"clrex\n\t"
> +		"mrc	p15, 0, r0, c1, c0, 1	@ get AUXCR\n\t"
> +		"bic	r0, r0, #(1 << 6)	@ disable local coherency\n\t"
> +		"mcr	p15, 0, r0, c1, c0, 1	@ set AUXCR\n\t"
> +		"isb\n\t"
> +		"dsb\n\t"
> +		"ldr	fp, [sp], #4"
> +		: : : "r0", "r1", "r2", "r3", "r4", "r5", "r6", "r7",
> +			"r9", "r10", "lr", "memory");
> +
> +		cci_disable_port_by_cpu(mpidr);
> +
> +		__mcpm_outbound_leave_critical(cluster, CLUSTER_DOWN);
> +
> +	} else {
> +		arch_spin_unlock(&edcs_lock);
> +		/*
> +			* We need to disable and flush only the L1 cache.
> +			* Let's do it in the safest possible way as above.
> +		*/
> +		asm volatile(
> +		"str	fp, [sp, #-4]!\n\t"
> +		"mrc	p15, 0, r0, c1, c0, 0	@ get CR\n\t"
> +		"bic	r0, r0, #"__stringify(CR_C)"\n\t"
> +		"mcr	p15, 0, r0, c1, c0, 0	@ set CR\n\t"
> +		"isb\n\t"
> +		"bl	v7_flush_dcache_louis\n\t"
> +		"clrex\n\t"
> +		"mrc	p15, 0, r0, c1, c0, 1	@ get AUXCR\n\t"
> +		"bic	r0, r0, #(1 << 6)	@ disable local coherency\n\t"
> +		"mcr	p15, 0, r0, c1, c0, 1	@ set AUXCR\n\t"
> +		"isb\n\t"
> +		"dsb\n\t"
> +		"ldr	fp, [sp], #4"
> +		: : : "r0", "r1", "r2", "r3", "r4", "r5", "r6", "r7",
> +		      "r9", "r10", "lr", "memory");
> +
> +	}
> +	__mcpm_cpu_down(cpu, cluster);
> +
> +	if (!skip_wfi) {
> +		exynos_core_power_down(cpu, cluster);
> +		wfi();
> +	}
> +}

I did not looked line by line but these functions looks very similar 
than the tc2_pm.c's function. no ?

May be some code consolidation could be considered here.

Added Nico and Lorenzo in Cc.

Thanks
   -- Daniel

> +static const struct mcpm_platform_ops exynos_power_ops = {
> +	.power_up	= exynos_power_up,
> +	.power_down	= exynos_power_down,
> +};
> +
> +static void __init edcs_data_init(void)
> +{
> +	unsigned int mpidr, cpu, cluster;
> +
> +	mpidr = read_cpuid_mpidr();
> +	cpu = MPIDR_AFFINITY_LEVEL(mpidr, 0);
> +	cluster = MPIDR_AFFINITY_LEVEL(mpidr, 1);
> +
> +	pr_debug("%s: cpu %u cluster %u\n", __func__, cpu, cluster);
> +	BUG_ON(cpu >= EDCS_CPUS_PER_CLUSTER  || cluster >= EDCS_CLUSTERS);
> +	edcs_use_count[cpu][cluster] = 1;
> +	++core_count[cluster];
> +}
> +
> +/*
> + * Enable cluster-level coherency, in preparation for turning on the MMU.
> + */
> +static void __naked edcs_power_up_setup(unsigned int affinity_level)
> +{
> +	asm volatile ("\n"
> +	"b	cci_enable_port_for_self");
> +}
> +
> +static int __init edcs_init(void)
> +{
> +	int ret;
> +	struct device_node *node;
> +
> +	node = of_find_compatible_node(NULL, NULL, "samsung,exynos5410");
> +	if (!node)
> +		return -ENODEV;
> +
> +	if (!cci_probed())
> +		return -ENODEV;
> +
> +	/*
> +	 * Future entries into the kernel can now go
> +	 * through the cluster entry vectors.
> +	 */
> +	__raw_writel(virt_to_phys(mcpm_entry_point),
> +				S5P_VA_SYSRAM_NS + 0x1c);
> +
> +	edcs_data_init();
> +	mcpm_smp_set_ops();
> +
> +	ret = mcpm_platform_register(&exynos_power_ops);
> +	if (!ret) {
> +		mcpm_sync_init(edcs_power_up_setup);
> +		pr_info("EDCS power management initialized\n");
> +	}
> +	return ret;
> +}
> +
> +early_initcall(edcs_init);
>


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