[U-Boot] [linux-sunxi] [RFC PATCH 7/8] sunxi: Add basic PSCI implementation for multi-cluster SoCs

[Chen-Yu Tsai <wens@csie.org>]

On Wed, Jun 7, 2017 at 8:47 AM, Icenowy Zheng <icenowy@aosc.io> wrote:
> From: Chen-Yu Tsai <wens@csie.org>
>
> Allwinner A80 and A83T SoCs have two clusters of CPU, each cluster
> contains 4 cores. A80 is Cortex-A15 + Cortex-A7 configuration, while
> A83T has two clusters of Cortex-A7.
>
> This patch adds a basic version that allows bringing up the four cores
> in the first cluster. The structure is based on existing sunxi PSCI code.
>
> Signed-off-by: Chen-Yu Tsai <wens@csie.org>
> [Icenowy: adapt for A83T]
> Signed-off-by: Icenowy Zheng <icenowy@aosc.io>
> ---
>  arch/arm/cpu/armv7/sunxi/Makefile    |   4 +
>  arch/arm/cpu/armv7/sunxi/psci-mcpm.c | 258 +++++++++++++++++++++++++++++++++++
>  2 files changed, 262 insertions(+)
>  create mode 100644 arch/arm/cpu/armv7/sunxi/psci-mcpm.c
>

I suggest using --find-copies and --find-copies-harder when you
generate the patch.
It should limit the patch to differences between psci.c and psci-mcpm.c.

> diff --git a/arch/arm/cpu/armv7/sunxi/Makefile b/arch/arm/cpu/armv7/sunxi/Makefile
> index 8c026ff052..c789f686fd 100644
> --- a/arch/arm/cpu/armv7/sunxi/Makefile
> +++ b/arch/arm/cpu/armv7/sunxi/Makefile
> @@ -14,8 +14,12 @@ obj-$(CONFIG_MACH_SUN8I_H3)  += tzpc.o
>  obj-$(CONFIG_MACH_SUN8I_A83T)  += tzpc.o
>
>  ifndef CONFIG_SPL_BUILD
> +ifdef CONFIG_MACH_SUN8I_A83T
> +obj-$(CONFIG_ARMV7_PSCI)       += psci-mcpm.o
> +else
>  obj-$(CONFIG_ARMV7_PSCI)       += psci.o
>  endif
> +endif
>
>  ifdef CONFIG_SPL_BUILD
>  obj-y  += fel_utils.o
> diff --git a/arch/arm/cpu/armv7/sunxi/psci-mcpm.c b/arch/arm/cpu/armv7/sunxi/psci-mcpm.c
> new file mode 100644
> index 0000000000..ba8d669c7e
> --- /dev/null
> +++ b/arch/arm/cpu/armv7/sunxi/psci-mcpm.c
> @@ -0,0 +1,258 @@
> +/*
> + * Copyright (C) 2016
> + * Author: Chen-Yu Tsai <wens@csie.org>
> + *
> + * Based on assembly code by Marc Zyngier <marc.zyngier@arm.com>,
> + * which was based on code by Carl van Schaik <carl@ok-labs.com>.
> + *
> + * SPDX-License-Identifier:    GPL-2.0
> + */
> +#include <config.h>
> +#include <common.h>
> +
> +#include <asm/arch/cpu.h>
> +#include <asm/arch/cpucfg.h>
> +#include <asm/arch/prcm.h>
> +#include <asm/armv7.h>
> +#include <asm/io.h>
> +#include <asm/psci.h>
> +#include <asm/secure.h>
> +
> +#include <linux/bitops.h>
> +
> +/*
> + * NOTE dense CPU IDs (0~3 for first cluster of 4 cores, 4~7 for the
> + * second cluster) are used throughout the PSCI code. Any MPIDR style
> + * values must be converted.
> + */
> +
> +/*
> + * Provide a dense CPU ID for 2-cluster systems. This must be coded in
> + * assembly as it gets called from psci_stack_setup, when the stack isn't
> + * available yet.
> + *
> + * Only r0 and r3 is usable. r8 - r12 are available if this function is
> + * only called from psci_stack_setup, which we cannot guarantee.
> + */
> +u32 __secure __naked psci_get_cpu_id(void)
> +{
> +       asm volatile (
> +               "mrc    p15, 0, r3, c0, c0, 5   @ Get MPIDR\n"
> +               "lsr    r0, r3, #6\n"
> +               "and    r3, r3, #3\n"
> +               "and    r0, r0, #4\n"
> +               "orr    r0, r0, r3\n"
> +               "bx     lr\n"
> +       );
> +
> +       /*
> +        * The last five lines are the compiler generated assembly code for
> +        *
> +        *      return (reg & 0x3) | (((reg >> 8) & 0x1) << 2);
> +        *
> +        * We can't guarantee that all compilers correctly use only r0 and
> +        * r3, so we use inline assembly here.
> +        */
> +}
> +
> +static void __secure cp15_write_cntp_tval(u32 tval)
> +{
> +       asm volatile ("mcr p15, 0, %0, c14, c2, 0" : : "r" (tval));
> +}
> +
> +static void __secure cp15_write_cntp_ctl(u32 val)
> +{
> +       asm volatile ("mcr p15, 0, %0, c14, c2, 1" : : "r" (val));
> +}
> +
> +static u32 __secure cp15_read_cntp_ctl(void)
> +{
> +       u32 val;
> +
> +       asm volatile ("mrc p15, 0, %0, c14, c2, 1" : "=r" (val));
> +
> +       return val;
> +}
> +
> +#define ONE_US (COUNTER_FREQUENCY / 1000000)
> +
> +/* Use a different name to avoid clashing with the non-secure function */
> +static void __secure __udelay_sec(unsigned long us)
> +{
> +       u32 reg = ONE_US * us;
> +
> +       cp15_write_cntp_tval(reg);
> +       isb();
> +       cp15_write_cntp_ctl(3);
> +
> +       do {
> +               isb();
> +               reg = cp15_read_cntp_ctl();
> +       } while (!(reg & BIT(2)));
> +
> +       cp15_write_cntp_ctl(0);
> +       isb();
> +}
> +
> +static void __secure clamp_release(u32 *clamp)
> +{
> +       writel(0xff, clamp);
> +       __udelay_sec(10);
> +       writel(0xfe, clamp);
> +       __udelay_sec(10);
> +       writel(0xf8, clamp);
> +       __udelay_sec(10);
> +       writel(0xf0, clamp);
> +       __udelay_sec(10);
> +       writel(0x00, clamp);
> +}
> +
> +static void __secure clamp_set(u32 *clamp)
> +{
> +       writel(0xff, clamp);
> +}
> +
> +static void __secure sunxi_core_power_switch(u32 *clamp, u32 *pwroff,
> +                                            bool on, int cpu)
> +{
> +       if (on) {
> +               /* Release power clamp */
> +               clamp_release(clamp);
> +
> +               __udelay_sec(20);
> +
> +               /* Clear power gating */
> +               clrbits_le32(pwroff, BIT(cpu));
> +       } else {
> +               /* Set power gating */
> +               setbits_le32(pwroff, BIT(cpu));
> +
> +               __udelay_sec(20);
> +
> +               /* Activate power clamp */
> +               clamp_set(clamp);
> +       }
> +}
> +
> +static int __secure sunxi_cluster_is_a7(int cluster)
> +{
> +#ifdef CONFIG_MACH_SUN8I_A83T
> +       return 1;
> +#else
> +       return (clustter == 0);
> +#endif
> +}
> +
> +static void __secure sunxi_cpu_set_power(int cluster, int cpu, bool on)
> +{
> +       struct sunxi_prcm_reg *prcm =
> +               (struct sunxi_prcm_reg *)SUNXI_PRCM_BASE;
> +
> +       sunxi_core_power_switch(&prcm->cpu_pwr_clamp[cluster][cpu],
> +                               &prcm->cpu_pwroff[cluster], on, cpu);
> +}
> +
> +static u32 __secure cp15_read_scr(void)
> +{
> +       u32 scr;
> +
> +       asm volatile ("mrc p15, 0, %0, c1, c1, 0" : "=r" (scr));
> +
> +       return scr;
> +}
> +
> +static void __secure cp15_write_scr(u32 scr)
> +{
> +       asm volatile ("mcr p15, 0, %0, c1, c1, 0" : : "r" (scr));
> +       isb();
> +}
> +
> +int __secure psci_cpu_on(u32 __always_unused unused, u32 mpidr, u32 pc)
> +{
> +       struct sunxi_cpucfg_reg *cpucfg =
> +               (struct sunxi_cpucfg_reg *)SUNXI_CPUCFG_BASE;
> +#ifdef CONFIG_MACH_SUN8I_A83T
> +       struct sunxi_r_cpucfg_reg *r_cpucfg =
> +               (struct sunxi_r_cpucfg_reg *)SUNXI_R_CPUCFG_BASE;
> +#else
> +       struct sunxi_prcm_reg *prcm =
> +               (struct sunxi_prcm_reg *)SUNXI_PRCM_BASE;
> +#endif
> +       u32 cluster = (mpidr >> 8) & 0x1;
> +       u32 cpu = mpidr & 0x3;
> +       u32 cpuid = cpu | (cluster << 2);
> +
> +       /* TODO We don't support multi-cluster yet */
> +       if (cluster > 0)
> +               return ARM_PSCI_RET_INVAL;
> +
> +       /* store target PC */
> +       psci_save_target_pc(cpuid, pc);
> +
> +       /* Set secondary core power on PC */
> +#ifdef CONFIG_MACH_SUN8I_A83T
> +       writel((u32)&psci_cpu_entry, &r_cpucfg->priv0);
> +#else
> +       writel((u32)&psci_cpu_entry, &prcm->cpu_soft_entry);
> +#endif

Could you take a look at the non-MCPM version and move the #ifdefs
into separate functions? Basically we want the main functions to
be as clean and descriptive as possible. You could also structure
it as two patches: the first adding the original A80 version, and
the second modifying it to support the A83T as well.

I'll send a fix for the non-MCPM version fixing the entry address.

Regards
ChenYu

> +
> +       /* Assert power-on reset on target CPU */
> +#ifdef CONFIG_MACH_SUN8I_A83T
> +       clrbits_le32(&r_cpucfg->cpu_rst[cluster], BIT(cpu));
> +#else
> +       clrbits_le32(&prcm->cpu_rst[cluster], BIT(cpu));
> +#endif
> +
> +       /* Cortex-A7: hold L1 cache reset disable signal low */
> +       if (sunxi_cluster_is_a7(cluster))
> +               clrbits_le32(&cpucfg->cluster[cluster].ctrl0,
> +                            CPUCFG_CX_CTRL0_L1_RST_DISABLE(cpu));
> +
> +       /* Lock CPU (Disable external debug access) */
> +       clrbits_le32(&cpucfg->cluster_reset[cluster],
> +                    CPUCFG_CX_RST_DBG(cpu));
> +
> +       /* Cortex-A7: Assert ETM reset */
> +       if (sunxi_cluster_is_a7(cluster))
> +               clrbits_le32(&cpucfg->cluster_reset[cluster],
> +                            CPUCFG_CX_RST_ETM(cpu));
> +
> +       /*
> +        * Allwinner code also asserts resets for NEON on A15. According
> +        * to ARM manuals, asserting power-on reset is sufficient.
> +        */
> +
> +       /* Power up target CPU */
> +       sunxi_cpu_set_power(cluster, cpu, true);
> +
> +       /* De-assert power-on reset on target CPU */
> +#ifdef CONFIG_MACH_SUN8I_A83T
> +       setbits_le32(&r_cpucfg->cpu_rst[cluster], BIT(cpu));
> +#else
> +       setbits_le32(&prcm->cpu_rst[cluster], BIT(cpu));
> +#endif
> +
> +       /* De-assert core reset on target CPU */
> +       setbits_le32(&cpucfg->cluster_reset[cluster],
> +                    CPUCFG_CX_RST_CORE(cpu));
> +
> +       /* Cortex-A7: De-assert ETM reset */
> +       if (sunxi_cluster_is_a7(cluster))
> +               setbits_le32(&cpucfg->cluster_reset[cluster],
> +                            CPUCFG_CX_RST_ETM(cpu));
> +
> +       /* Unlock CPU (Disable external debug access) */
> +       setbits_le32(&cpucfg->cluster_reset[cluster],
> +                    CPUCFG_CX_RST_DBG(cpu));
> +
> +       return ARM_PSCI_RET_SUCCESS;
> +}
> +
> +void __secure psci_arch_init(void)
> +{
> +       u32 reg;
> +
> +       reg = cp15_read_scr();
> +       reg &= ~BIT(0); /* Secure mode */
> +       cp15_write_scr(reg);
> +}
> --
> 2.12.2
>
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