[U-Boot] [PATCH v3 02/11] Exynos542x: CPU: Power down all secondary cores
Akshay Saraswat
akshay.s at samsung.com
Wed Feb 18 13:06:11 CET 2015
Hi Lukasz,
>Hi Akshay,
>
>> 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.
>
>Could you provide exact names of those registers? I'm familiar with
>Samsung SoCs but I cannot recall which one those are.
>
As I have written in Step-2, these are addresses (SRAM) and not registers.
Our iROM code has a part where it reads 0x02020028 for a specific vlaue
FCBA0D10. If CPU finds that value then it extracts jump address from
0x02020004, else it follows normal boot path.
>It would provide more readability to this commit message. Please fix it
>globally.
>
>> 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 <kimoon.kim at samsung.com>
>> Signed-off-by: Akshay Saraswat <akshay.s at samsung.com>
>> ---
>> Changes since v2:
>> - No change.
>>
>> Changes since v1:
>> - Removed unnecessary macros.
>> - Changed names of few macros for better understanding.
>> - Added MPIDR bit assignment info comment in power_down_core.
>>
>> arch/arm/cpu/armv7/exynos/exynos5_setup.h | 3 ++
>> arch/arm/cpu/armv7/exynos/lowlevel_init.c | 69
>> ++++++++++++++++++++++++ arch/arm/include/asm/arch-exynos/cpu.h |
>> 5 ++ arch/arm/include/asm/arch-exynos/system.h | 87
>> +++++++++++++++++++++++++++++++ 4 files changed, 164 insertions(+)
>>
>> diff --git a/arch/arm/cpu/armv7/exynos/exynos5_setup.h
>> b/arch/arm/cpu/armv7/exynos/exynos5_setup.h index 2eea48a..9073f50
>> 100644 --- a/arch/arm/cpu/armv7/exynos/exynos5_setup.h
>> +++ b/arch/arm/cpu/armv7/exynos/exynos5_setup.h
>> @@ -700,6 +700,9 @@
>> #define CLK_DIV_CPERI1_VAL NOT_AVAILABLE
>>
>> #else
>> +
>> +#define CPU_CONFIG_STATUS_OFFSET 0x80
>> +#define CPU_RST_FLAG_VAL 0xFCBA0D10
>> #define PAD_RETENTION_DRAM_COREBLK_VAL 0x10000000
>>
>> /* APLL_CON1 */
>> diff --git a/arch/arm/cpu/armv7/exynos/lowlevel_init.c
>> b/arch/arm/cpu/armv7/exynos/lowlevel_init.c index 83e1dcf..e36f2fa
>> 100644 --- a/arch/arm/cpu/armv7/exynos/lowlevel_init.c
>> +++ b/arch/arm/cpu/armv7/exynos/lowlevel_init.c
>> @@ -31,7 +31,9 @@
>> #include <asm/arch/tzpc.h>
>> #include <asm/arch/periph.h>
>> #include <asm/arch/pinmux.h>
>> +#include <asm/arch/system.h>
>> #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) {
>> diff --git a/arch/arm/include/asm/arch-exynos/cpu.h
>> b/arch/arm/include/asm/arch-exynos/cpu.h index 29674ad..e739520 100644
>> --- a/arch/arm/include/asm/arch-exynos/cpu.h
>> +++ b/arch/arm/include/asm/arch-exynos/cpu.h
>> @@ -153,6 +153,10 @@
>> #define EXYNOS5420_CLOCK_BASE 0x10010000
>> #define EXYNOS5420_POWER_BASE 0x10040000
>> #define EXYNOS5420_SWRESET 0x10040400
>> +#define EXYNOS5420_INFORM_BASE 0x10040800
>> +#define EXYNOS5420_SPARE_BASE 0x10040900
>> +#define EXYNOS5420_CPU_CONFIG_BASE 0x10042000
>> +#define EXYNOS5420_CPU_STATUS_BASE 0x10042004
>> #define EXYNOS5420_SYSREG_BASE 0x10050000
>> #define EXYNOS5420_TZPC_BASE 0x100E0000
>> #define EXYNOS5420_WATCHDOG_BASE 0x101D0000
>> @@ -186,6 +190,7 @@
>> #define EXYNOS5420_USB3PHY_BASE DEVICE_NOT_AVAILABLE
>> #define EXYNOS5420_USB_HOST_XHCI_BASE DEVICE_NOT_AVAILABLE
>>
>> +
>> #ifndef __ASSEMBLY__
>> #include <asm/io.h>
>> /* CPU detection macros */
>> diff --git a/arch/arm/include/asm/arch-exynos/system.h
>> b/arch/arm/include/asm/arch-exynos/system.h index 4968d3d..86903c3
>> 100644 --- a/arch/arm/include/asm/arch-exynos/system.h
>> +++ b/arch/arm/include/asm/arch-exynos/system.h
>> @@ -37,6 +37,93 @@ struct exynos5_sysreg {
>>
>> #define USB20_PHY_CFG_HOST_LINK_EN (1 << 0)
>>
>> +#ifdef CONFIG_EXYNOS5420
>> +/*
>> + * Data Synchronization Barrier acts as a special kind of memory
>> barrier.
>> + * No instruction in program order after this instruction executes
>> until
>> + * this instruction completes. This instruction completes when:
>> + * - All explicit memory accesses before this instruction complete.
>> + * - All Cache, Branch predictor and TLB maintenance operations
>> before
>> + * this instruction complete.
>> + */
>> +#define dsb() __asm__ __volatile__ ("dsb\n\t" : : );
>> +
>> +/*
>> + * This instruction causes an event to be signaled to all cores
>> + * within a multiprocessor system. If SEV is implemented,
>> + * WFE must also be implemented.
>> + */
>> +#define sev() __asm__ __volatile__ ("sev\n\t" : : );
>> +/*
>> + * If the Event Register is not set, WFE suspends execution until
>> + * one of the following events occurs:
>> + * - an IRQ interrupt, unless masked by the CPSR I-bit
>> + * - an FIQ interrupt, unless masked by the CPSR F-bit
>> + * - an Imprecise Data abort, unless masked by the CPSR A-bit
>> + * - a Debug Entry request, if Debug is enabled
>> + * - an Event signaled by another processor using the SEV
>> instruction.
>> + * If the Event Register is set, WFE clears it and returns
>> immediately.
>> + * If WFE is implemented, SEV must also be implemented.
>> + */
>> +#define wfe() __asm__ __volatile__ ("wfe\n\t" : : );
>> +
>> +/* Move 0xd3 value to CPSR register to enable SVC mode */
>> +#define svc32_mode_en() __asm__
>> __volatile__ \
>> + ("@ I&F disable, Mode: 0x13 -
>> SVC\n\t" \
>> + "msr cpsr_c, #0x13|0xC0\n\t" : : )
>> +
>> +/* Set program counter with the given value */
>> +#define set_pc(x) __asm__ __volatile__ ("mov pc, %0\n\t" : :
>> "r"(x)) +
>> +/* Read Main Id register */
>> +#define mrc_midr(x) __asm__ __volatile__ \
>> + ("mrc p15, 0, %0, c0, c0, 0\n\t" :
>> "=r"(x) : ) +
>> +/* Read Multiprocessor Affinity Register */
>> +#define mrc_mpafr(x) __asm__ __volatile__ \
>> + ("mrc p15, 0, %0, c0, c0, 5\n\t" :
>> "=r"(x) : ) +
>> +/* Read System Control Register */
>> +#define mrc_sctlr(x) __asm__ __volatile__ \
>> + ("mrc p15, 0, %0, c1, c0, 0\n\t" :
>> "=r"(x) : ) +
>> +/* Read Auxiliary Control Register */
>> +#define mrc_auxr(x) __asm__ __volatile__ \
>> + ("mrc p15, 0, %0, c1, c0, 1\n\t" :
>> "=r"(x) : ) +
>> +/* Read L2 Control register */
>> +#define mrc_l2_ctlr(x) __asm__ __volatile__ \
>> + ("mrc p15, 1, %0, c9, c0, 2\n\t" :
>> "=r"(x) : ) +
>> +/* Read L2 Auxilliary Control register */
>> +#define mrc_l2_aux_ctlr(x) __asm__ __volatile__ \
>> + ("mrc p15, 1, %0, c15, c0, 0\n\t" :
>> "=r"(x) : ) +
>> +/* Write System Control Register */
>> +#define mcr_sctlr(x) __asm__ __volatile__ \
>> + ("mcr p15, 0, %0, c1, c0, 0\n\t" : :
>> "r"(x)) +
>> +/* Write Auxiliary Control Register */
>> +#define mcr_auxr(x) __asm__ __volatile__ \
>> + ("mcr p15, 0, %0, c1, c0, 1\n\t" : :
>> "r"(x)) +
>> +/* Invalidate all instruction caches to PoU */
>> +#define mcr_icache(x) __asm__ __volatile__ \
>> + ("mcr p15, 0, %0, c7, c5, 0\n\t" : :
>> "r"(x)) +
>> +/* Invalidate unified TLB */
>> +#define mcr_tlb(x) __asm__ __volatile__ \
>> + ("mcr p15, 0, %0, c8, c7, 0\n\t" : :
>> "r"(x)) +
>> +/* Write L2 Control register */
>> +#define mcr_l2_ctlr(x) __asm__ __volatile__ \
>> + ("mcr p15, 1, %0, c9, c0, 2\n\t" : :
>> "r"(x)) +
>> +/* Write L2 Auxilliary Control register */
>> +#define mcr_l2_aux_ctlr(x) __asm__ __volatile__ \
>> + ("mcr p15, 1, %0, c15, c0, 0\n\t" : :
>> "r"(x)) +#endif
>> +
>> void set_usbhost_mode(unsigned int mode);
>> void set_system_display_ctrl(void);
>> int exynos_lcd_early_init(const void *blob);
>
>--
>Best regards,
>
>Lukasz Majewski
>
>Samsung R&D Institute Poland (SRPOL) | Linux Platform Group
Regards,
Akshay Saraswat
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