From ac0d98cd557e0939bd0f10ff68e2e648a74bbea6 Mon Sep 17 00:00:00 2001 From: Akshay Saraswat Date: Fri, 20 Feb 2015 13:27:12 +0530 Subject: Exynos542x: CPU: Power down all secondary cores This patch adds code to shutdown secondary cores. When U-boot comes up, all secondary cores appear powered on, which is undesirable and causes side effects while initializing these cores in kernel. Secondary core power down happens in following steps: Step-1: After Exynos power-on, primary core starts executing first. Step-2: In iROM code every core has to check 2 flags i.e. addresses 0x02020028 & 0x02020004. Step-3: Initially 0x02020028 is 0 for all cores and 0x02020004 has a jump address for primary core and 0 for all secondary cores. Step-4: Therefore, primary core follows normal iROM execution and jumps to BL1 eventually, whereas all secondary cores enter WFE. Step-5: When primary core comes into function secondary_cores_configure, it puts pointer to function power_down_core into 0x02020004 and provides DSB and SEV for all cores so that they may come out of WFE and jump to power_down_core function. Step-6: And ultimately because of power_down_core all secondary cores shut-down. Signed-off-by: Kimoon Kim Signed-off-by: Akshay Saraswat Signed-off-by: Minkyu Kang --- arch/arm/cpu/armv7/exynos/lowlevel_init.c | 69 +++++++++++++++++++++++++++++++ 1 file changed, 69 insertions(+) (limited to 'arch/arm/cpu/armv7/exynos/lowlevel_init.c') diff --git a/arch/arm/cpu/armv7/exynos/lowlevel_init.c b/arch/arm/cpu/armv7/exynos/lowlevel_init.c index 83e1dcfc1e..e36f2fad6d 100644 --- a/arch/arm/cpu/armv7/exynos/lowlevel_init.c +++ b/arch/arm/cpu/armv7/exynos/lowlevel_init.c @@ -31,7 +31,9 @@ #include #include #include +#include #include "common_setup.h" +#include "exynos5_setup.h" /* These are the things we can do during low-level init */ enum { @@ -42,6 +44,68 @@ enum { DO_POWER = 1 << 4, }; +#ifdef CONFIG_EXYNOS5420 +/* + * Pointer to this function is stored in iRam which is used + * for jump and power down of a specific core. + */ +static void power_down_core(void) +{ + uint32_t tmp, core_id, core_config; + + /* Get the unique core id */ + /* + * Multiprocessor Affinity Register + * [11:8] Cluster ID + * [1:0] CPU ID + */ + mrc_mpafr(core_id); + tmp = core_id & 0x3; + core_id = (core_id >> 6) & ~3; + core_id |= tmp; + core_id &= 0x3f; + + /* Set the status of the core to low */ + core_config = (core_id * CPU_CONFIG_STATUS_OFFSET); + core_config += EXYNOS5420_CPU_CONFIG_BASE; + writel(0x0, core_config); + + /* Core enter WFI */ + wfi(); +} + +/* + * Configurations for secondary cores are inapt at this stage. + * Reconfigure secondary cores. Shutdown and change the status + * of all cores except the primary core. + */ +static void secondary_cores_configure(void) +{ + uint32_t core_id; + + /* Store jump address for power down of secondary cores */ + writel((uint32_t)&power_down_core, CONFIG_PHY_IRAM_BASE + 0x4); + + /* Need all core power down check */ + dsb(); + sev(); + + /* + * Power down all cores(secondary) while primary core must + * wait for all cores to go down. + */ + for (core_id = 1; core_id != CONFIG_CORE_COUNT; core_id++) { + while ((readl(EXYNOS5420_CPU_STATUS_BASE + + (core_id * CPU_CONFIG_STATUS_OFFSET)) + & 0xff) != 0x0) { + isb(); + sev(); + } + isb(); + } +} +#endif + int do_lowlevel_init(void) { uint32_t reset_status; @@ -49,6 +113,11 @@ int do_lowlevel_init(void) arch_cpu_init(); +#ifdef CONFIG_EXYNOS5420 + /* Reconfigure secondary cores */ + secondary_cores_configure(); +#endif + reset_status = get_reset_status(); switch (reset_status) { -- cgit v1.2.1