On Fri, 2 May 2014, Abhilash Kesavan wrote: > Add machine-dependent MCPM call-backs for Exynos5420. These are used > to power up/down the secondary CPUs during boot, shutdown, s2r and > switching. > > Signed-off-by: Thomas Abraham <thomas.ab@xxxxxxxxxxx> > Signed-off-by: Inderpal Singh <inderpal.s@xxxxxxxxxxx> > Signed-off-by: Andrew Bresticker <abrestic@xxxxxxxxxxxx> > Signed-off-by: Abhilash Kesavan <a.kesavan@xxxxxxxxxxx> OK.... There is still a detail wrong. At least we are converging. > --- > arch/arm/mach-exynos/Kconfig | 8 + > arch/arm/mach-exynos/Makefile | 2 + > arch/arm/mach-exynos/mcpm-exynos.c | 345 ++++++++++++++++++++++++++++++++++++ > arch/arm/mach-exynos/regs-pmu.h | 3 + > 4 files changed, 358 insertions(+) > create mode 100644 arch/arm/mach-exynos/mcpm-exynos.c > > diff --git a/arch/arm/mach-exynos/Kconfig b/arch/arm/mach-exynos/Kconfig > index 5c34dc2..138070e 100644 > --- a/arch/arm/mach-exynos/Kconfig > +++ b/arch/arm/mach-exynos/Kconfig > @@ -73,4 +73,12 @@ config SOC_EXYNOS5440 > > endmenu > > +config EXYNOS5420_MCPM > + bool "Exynos5420 Multi-Cluster PM support" > + depends on MCPM && SOC_EXYNOS5420 > + select ARM_CCI > + help > + This is needed to provide CPU and cluster power management > + on Exynos5420 implementing big.LITTLE. > + > endif > diff --git a/arch/arm/mach-exynos/Makefile b/arch/arm/mach-exynos/Makefile > index a656dbe..01bc9b9 100644 > --- a/arch/arm/mach-exynos/Makefile > +++ b/arch/arm/mach-exynos/Makefile > @@ -29,3 +29,5 @@ obj-$(CONFIG_ARCH_EXYNOS) += firmware.o > > plus_sec := $(call as-instr,.arch_extension sec,+sec) > AFLAGS_exynos-smc.o :=-Wa,-march=armv7-a$(plus_sec) > + > +obj-$(CONFIG_EXYNOS5420_MCPM) += mcpm-exynos.o > diff --git a/arch/arm/mach-exynos/mcpm-exynos.c b/arch/arm/mach-exynos/mcpm-exynos.c > new file mode 100644 > index 0000000..d0f7461 > --- /dev/null > +++ b/arch/arm/mach-exynos/mcpm-exynos.c > @@ -0,0 +1,345 @@ > +/* > + * Copyright (c) 2014 Samsung Electronics Co., Ltd. > + * http://www.samsung.com > + * > + * arch/arm/mach-exynos/mcpm-exynos.c > + * > + * Based on arch/arm/mach-vexpress/dcscb.c > + * > + * 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/arm-cci.h> > +#include <linux/delay.h> > +#include <linux/io.h> > +#include <linux/of_address.h> > + > +#include <asm/cputype.h> > +#include <asm/cp15.h> > +#include <asm/mcpm.h> > + > +#include "regs-pmu.h" > +#include "common.h" > + > +#define EXYNOS5420_CPUS_PER_CLUSTER 4 > +#define EXYNOS5420_NR_CLUSTERS 2 > + > +/* Non-secure iRAM base address */ > +static void __iomem *ns_sram_base_addr; > + > +/* > + * The common v7_exit_coherency_flush API could not be used because of the > + * Erratum 799270 workaround. This macro is the same as the common one (in > + * arch/arm/include/asm/cacheflush.h) except for the erratum handling. > + */ > +#define exynos_v7_exit_coherency_flush(level) \ > + asm volatile( \ > + "stmfd sp!, {fp, ip}\n\t"\ > + "mrc p15, 0, r0, c1, c0, 0 @ get SCTLR\n\t" \ > + "bic r0, r0, #"__stringify(CR_C)"\n\t" \ > + "mcr p15, 0, r0, c1, c0, 0 @ set SCTLR\n\t" \ > + "isb\n\t"\ > + "bl v7_flush_dcache_"__stringify(level)"\n\t" \ > + "clrex\n\t"\ > + "mrc p15, 0, r0, c1, c0, 1 @ get ACTLR\n\t" \ > + "bic r0, r0, #(1 << 6) @ disable local coherency\n\t" \ > + /* Dummy Load of a device register to avoid Erratum 799270 */ \ > + "ldr r4, [%0]\n\t" \ > + "and r4, r4, #0\n\t" \ > + "orr r0, r0, r4\n\t" \ > + "mcr p15, 0, r0, c1, c0, 1 @ set ACTLR\n\t" \ > + "isb\n\t" \ > + "dsb\n\t" \ > + "ldmfd sp!, {fp, ip}" \ > + : \ > + : "Ir" (S5P_INFORM0) \ > + : "r0", "r1", "r2", "r3", "r4", "r5", "r6", "r7", \ > + "r9", "r10", "lr", "memory") > + > +/* > + * We can't use regular spinlocks. In the switcher case, it is possible > + * for an outbound CPU to call power_down() after its inbound counterpart > + * is already live using the same logical CPU number which trips lockdep > + * debugging. > + */ > +static arch_spinlock_t exynos_mcpm_lock = __ARCH_SPIN_LOCK_UNLOCKED; > +static int > +cpu_use_count[EXYNOS5420_CPUS_PER_CLUSTER][EXYNOS5420_NR_CLUSTERS]; > + > +#define exynos_cluster_unused(cluster) \ > + (!cpu_use_count[0][cluster] && \ > + !cpu_use_count[1][cluster] && \ > + !cpu_use_count[2][cluster] && \ > + !cpu_use_count[3][cluster]) > + > +static int exynos_cluster_power_control(unsigned int cluster, int enable) > +{ > + unsigned int tries = 100; > + unsigned int val; > + > + if (enable) { > + exynos_cluster_powerup(cluster); > + val = S5P_CORE_LOCAL_PWR_EN; > + } else { > + exynos_cluster_powerdown(cluster); > + val = 0; > + } > + > + /* Wait until cluster power control is applied */ > + while (tries--) { > + if (exynos_cluster_power_state(cluster) == val) > + return 0; > + > + cpu_relax(); > + } > + pr_warn("timed out waiting for cluster %u to power %s\n", cluster, > + enable ? "on" : "off"); > + > + return -ETIMEDOUT; > +} > + > +static int exynos_power_up(unsigned int cpu, unsigned int cluster) > +{ > + unsigned int cpunr = cpu + (cluster * EXYNOS5420_CPUS_PER_CLUSTER); > + int err = 0; > + > + pr_debug("%s: cpu %u cluster %u\n", __func__, cpu, cluster); > + if (cpu >= EXYNOS5420_CPUS_PER_CLUSTER || > + cluster >= EXYNOS5420_NR_CLUSTERS) > + return -EINVAL; > + > + /* > + * Since this is called with IRQs enabled, and no arch_spin_lock_irq > + * variant exists, we need to disable IRQs manually here. > + */ > + local_irq_disable(); > + arch_spin_lock(&exynos_mcpm_lock); > + > + cpu_use_count[cpu][cluster]++; > + if (cpu_use_count[cpu][cluster] == 1) { > + bool was_cluster_down = > + __mcpm_cluster_state(cluster) == CLUSTER_DOWN; This is racy. I probably made this comment already. The MCPM cluster state may change in mcpm-head.S where concurrency protection is achieved with a different mechanism. What you should do instead is to redefine exynos_cluster_unused() into exynos_cluster_usecnt() and simply add all counts together. You could even have: #define exynos_cluster_unused(cluster) !exynos_cluster_usecnt(cluster) Yet, here you should use: bool was_cluster_down = (exynos_cluster_usecnt(cluster) == 1); > + > + /* > + * Turn on the cluster (L2/COMMON) and then power on the > + * cores. > + */ > + if (was_cluster_down) > + err = exynos_cluster_power_control(cluster, 1); > + > + if (!err) > + exynos_cpu_powerup(cpunr); > + else > + exynos_cluster_power_control(cluster, 0); > + } else if (cpu_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(&exynos_mcpm_lock); > + local_irq_enable(); > + > + return err; > +} > + > +static void exynos_power_down(void) > +{ > + unsigned int mpidr, cpu, cluster; > + bool last_man = false, skip_wfi = false; > + unsigned int cpunr; > + > + mpidr = read_cpuid_mpidr(); > + cpu = MPIDR_AFFINITY_LEVEL(mpidr, 0); > + cluster = MPIDR_AFFINITY_LEVEL(mpidr, 1); > + cpunr = cpu + (cluster * EXYNOS5420_CPUS_PER_CLUSTER); > + > + pr_debug("%s: cpu %u cluster %u\n", __func__, cpu, cluster); > + BUG_ON(cpu >= EXYNOS5420_CPUS_PER_CLUSTER || > + cluster >= EXYNOS5420_NR_CLUSTERS); > + > + __mcpm_cpu_going_down(cpu, cluster); > + > + arch_spin_lock(&exynos_mcpm_lock); > + BUG_ON(__mcpm_cluster_state(cluster) != CLUSTER_UP); > + cpu_use_count[cpu][cluster]--; > + if (cpu_use_count[cpu][cluster] == 0) { > + exynos_cpu_powerdown(cpunr); > + > + if (exynos_cluster_unused(cluster)) > + last_man = true; > + } else if (cpu_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(); > + } > + > + /* > + * TODO: Turn off the clusters when all cores in the cluster > + * are down to achieve significant power savings. > + */ This comment should actually be located right after the "if (exynos_cluster_unused(cluster))" above. That is where the cluster control should be applied, assuming it'll be effective only when WFI is executed. > + if (last_man && __mcpm_outbound_enter_critical(cpu, cluster)) { > + arch_spin_unlock(&exynos_mcpm_lock); > + > + /* Flush all cache levels for this cluster. */ > + exynos_v7_exit_coherency_flush(all); > + > + /* > + * Disable cluster-level coherency by masking > + * incoming snoops and DVM messages: > + */ > + cci_disable_port_by_cpu(mpidr); > + > + __mcpm_outbound_leave_critical(cluster, CLUSTER_DOWN); > + } else { > + arch_spin_unlock(&exynos_mcpm_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)); > + } This doesn't belong here. That is for the last_man only to do, right before the "Flush all cache levels for this cluster" comment. The rest looks fine to me. Nicolas -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
