Re: [PATCH 1/4] ARM: sun9i: Support SMP on A80 with Multi-Cluster Power Management (MCPM)

[Maxime Ripard]

Hi Chen-Yu,

On Tue, Jul 25, 2017 at 01:09:16PM +0800, Chen-Yu Tsai wrote:
> The A80 is a big.LITTLE SoC with 1 cluster of 4 Cortex-A7s and
> 1 cluster of 4 Cortex-A15s.
> 
> This patch adds support to bring up the second cluster and thus all
> cores using the common MCPM code. Core/cluster power down has not
> been implemented, thus CPU hotplugging and big.LITTLE switcher is
> not supported.
> 
> Signed-off-by: Chen-Yu Tsai <wens@xxxxxxxx>
> ---
>  arch/arm/mach-sunxi/Kconfig  |  10 ++
>  arch/arm/mach-sunxi/Makefile |   1 +
>  arch/arm/mach-sunxi/mcpm.c   | 391 +++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 402 insertions(+)
>  create mode 100644 arch/arm/mach-sunxi/mcpm.c
> 
> diff --git a/arch/arm/mach-sunxi/Kconfig b/arch/arm/mach-sunxi/Kconfig
> index 58153cdf025b..177380548d99 100644
> --- a/arch/arm/mach-sunxi/Kconfig
> +++ b/arch/arm/mach-sunxi/Kconfig
> @@ -47,5 +47,15 @@ config MACH_SUN9I
>  	bool "Allwinner (sun9i) SoCs support"
>  	default ARCH_SUNXI
>  	select ARM_GIC
> +	imply MCPM
> +
> +config SUN9I_A80_MCPM
> +	bool "Allwinner A80 Multi-Cluster PM support"
> +	depends on MCPM && MACH_SUN9I
> +	default MACH_SUN9I
> +	select ARM_CCI400_PORT_CTRL
> +	help
> +	  This is needed to provide CPU and cluster power management
> +	  on Allwinner A80 implementing big.LITTLE.

Do we really need an option for that? we don't provide the option to
disable the CPU SMP operations for the rest of the SoCs.

>  endif
> diff --git a/arch/arm/mach-sunxi/Makefile b/arch/arm/mach-sunxi/Makefile
> index 27b168f121a1..e8558912c714 100644
> --- a/arch/arm/mach-sunxi/Makefile
> +++ b/arch/arm/mach-sunxi/Makefile
> @@ -1,2 +1,3 @@
>  obj-$(CONFIG_ARCH_SUNXI) += sunxi.o
>  obj-$(CONFIG_SMP) += platsmp.o
> +obj-$(CONFIG_SUN9I_A80_MCPM) += mcpm.o
> diff --git a/arch/arm/mach-sunxi/mcpm.c b/arch/arm/mach-sunxi/mcpm.c
> new file mode 100644
> index 000000000000..4b6e1d6ae379
> --- /dev/null
> +++ b/arch/arm/mach-sunxi/mcpm.c
> @@ -0,0 +1,391 @@
> +/*
> + * Copyright (c) 2015 Chen-Yu Tsai
> + *
> + * Chen-Yu Tsai <wens@xxxxxxxx>
> + *
> + * arch/arm/mach-sunxi/mcpm.c
> + *
> + * Based on arch/arm/mach-exynos/mcpm-exynos.c and Allwinner code
> + *
> + * 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>
> +
> +#define SUNXI_CPUS_PER_CLUSTER		4
> +#define SUNXI_NR_CLUSTERS		2
> + 
> +#define SUN9I_A80_A15_CLUSTER		1

Don't we have a way to derive that from the DT ?

> +#define CPUCFG_CX_CTRL_REG0(c)		(0x10 * (c))
> +#define CPUCFG_CX_CTRL_REG0_L1_RST_DISABLE(n)	BIT(n)
> +#define CPUCFG_CX_CTRL_REG0_L1_RST_DISABLE_ALL	0xf
> +#define CPUCFG_CX_CTRL_REG0_L2_RST_DISABLE_A7	BIT(4)
> +#define CPUCFG_CX_CTRL_REG0_L2_RST_DISABLE_A15	BIT(0)
> +#define CPUCFG_CX_CTRL_REG1(c)		(0x10 * (c) + 0x4)
> +#define CPUCFG_CX_CTRL_REG1_ACINACTM	BIT(0)
> +#define CPUCFG_CX_RST_CTRL(c)		(0x80 + 0x4 * (c))
> +#define CPUCFG_CX_RST_CTRL_DBG_SOC_RST	BIT(24)
> +#define CPUCFG_CX_RST_CTRL_ETM_RST(n)	BIT(20 + (n))
> +#define CPUCFG_CX_RST_CTRL_ETM_RST_ALL	(0xf << 20)
> +#define CPUCFG_CX_RST_CTRL_DBG_RST(n)	BIT(16 + (n))
> +#define CPUCFG_CX_RST_CTRL_DBG_RST_ALL	(0xf << 16)
> +#define CPUCFG_CX_RST_CTRL_H_RST	BIT(12)
> +#define CPUCFG_CX_RST_CTRL_L2_RST	BIT(8)
> +#define CPUCFG_CX_RST_CTRL_CX_RST(n)	BIT(4 + (n))
> +#define CPUCFG_CX_RST_CTRL_CORE_RST(n)	BIT(n)
> +
> +#define PRCM_CPU_PO_RST_CTRL(c)		(0x4 + 0x4 * (c))
> +#define PRCM_CPU_PO_RST_CTRL_CORE(n)	BIT(n)
> +#define PRCM_CPU_PO_RST_CTRL_CORE_ALL	0xf
> +#define PRCM_PWROFF_GATING_REG(c)	(0x100 + 0x4 * (c))
> +#define PRCM_PWROFF_GATING_REG_CLUSTER	BIT(4)
> +#define PRCM_PWROFF_GATING_REG_CORE(n)	BIT(n)
> +#define PRCM_PWR_SWITCH_REG(c, cpu)	(0x140 + 0x10 * (c) + 0x4 * (cpu))
> +#define PRCM_CPU_SOFT_ENTRY_REG		0x164
> +
> +static void __iomem *cpucfg_base;
> +static void __iomem *prcm_base;
> +
> +static int sunxi_cpu_power_switch_set(unsigned int cpu, unsigned int cluster,
> +				      bool enable)
> +{
> +	u32 reg;
> +
> +	/* control sequence from Allwinner A80 user manual v1.2 PRCM section */
> +	reg = readl(prcm_base + PRCM_PWR_SWITCH_REG(cluster, cpu));
> +	if (enable) {
> +		if (reg == 0x00) {
> +			pr_debug("power clamp for cluster %u cpu %u already open\n",
> +				 cluster, cpu);
> +			return 0;
> +		}
> +
> +		writel(0xff, prcm_base + PRCM_PWR_SWITCH_REG(cluster, cpu));
> +		udelay(10);
> +		writel(0xfe, prcm_base + PRCM_PWR_SWITCH_REG(cluster, cpu));
> +		udelay(10);
> +		writel(0xf8, prcm_base + PRCM_PWR_SWITCH_REG(cluster, cpu));
> +		udelay(10);
> +		writel(0xf0, prcm_base + PRCM_PWR_SWITCH_REG(cluster, cpu));
> +		udelay(10);
> +		writel(0x00, prcm_base + PRCM_PWR_SWITCH_REG(cluster, cpu));
> +		udelay(10);
> +	} else {
> +		writel(0xff, prcm_base + PRCM_PWR_SWITCH_REG(cluster, cpu));
> +		udelay(10);
> +	}
> +
> +	return 0;
> +}
> +
> +static int sunxi_cpu_powerup(unsigned int cpu, unsigned int cluster)
> +{
> +	u32 reg;
> +
> +	pr_debug("%s: cpu %u cluster %u\n", __func__, cpu, cluster);
> +	if (cpu >= SUNXI_CPUS_PER_CLUSTER || cluster >= SUNXI_NR_CLUSTERS)
> +		return -EINVAL;
> +
> +	/* assert processor power-on reset */
> +	reg = readl(prcm_base + PRCM_CPU_PO_RST_CTRL(cluster));
> +	reg &= ~PRCM_CPU_PO_RST_CTRL_CORE(cpu);
> +	writel(reg, prcm_base + PRCM_CPU_PO_RST_CTRL(cluster));
> +
> +	/* Cortex-A7: hold L1 reset disable signal low */
> +	if (!(of_machine_is_compatible("allwinner,sun9i-a80") &&
> +			cluster == SUN9I_A80_A15_CLUSTER)) {
> +		reg = readl(cpucfg_base + CPUCFG_CX_CTRL_REG0(cluster));
> +		reg &= ~CPUCFG_CX_CTRL_REG0_L1_RST_DISABLE(cpu);
> +		writel(reg, cpucfg_base + CPUCFG_CX_CTRL_REG0(cluster));
> +	}
> +
> +	/* assert processor related resets */
> +	reg = readl(cpucfg_base + CPUCFG_CX_RST_CTRL(cluster));
> +	reg &= ~CPUCFG_CX_RST_CTRL_DBG_RST(cpu);
> +
> +	/*
> +	 * Allwinner code also asserts resets for NEON on A15. According
> +	 * to ARM manuals, asserting power-on reset is sufficient.
> +	 */
> +	if (!(of_machine_is_compatible("allwinner,sun9i-a80") &&
> +			cluster == SUN9I_A80_A15_CLUSTER)) {
> +		reg &= ~CPUCFG_CX_RST_CTRL_ETM_RST(cpu);
> +	}
> +	writel(reg, cpucfg_base + CPUCFG_CX_RST_CTRL(cluster));
> +
> +	/* open power switch */
> +	sunxi_cpu_power_switch_set(cpu, cluster, true);
> +
> +	/* clear processor power gate */
> +	reg = readl(prcm_base + PRCM_PWROFF_GATING_REG(cluster));
> +	reg &= ~PRCM_PWROFF_GATING_REG_CORE(cpu);
> +	writel(reg, prcm_base + PRCM_PWROFF_GATING_REG(cluster));
> +	udelay(20);
> +
> +	/* de-assert processor power-on reset */
> +	reg = readl(prcm_base + PRCM_CPU_PO_RST_CTRL(cluster));
> +	reg |= PRCM_CPU_PO_RST_CTRL_CORE(cpu);
> +	writel(reg, prcm_base + PRCM_CPU_PO_RST_CTRL(cluster));
> +
> +	/* de-assert all processor resets */
> +	reg = readl(cpucfg_base + CPUCFG_CX_RST_CTRL(cluster));
> +	reg |= CPUCFG_CX_RST_CTRL_DBG_RST(cpu);
> +	reg |= CPUCFG_CX_RST_CTRL_CORE_RST(cpu);
> +	if (!(of_machine_is_compatible("allwinner,sun9i-a80") &&
> +			cluster == SUN9I_A80_A15_CLUSTER)) {
> +		reg |= CPUCFG_CX_RST_CTRL_ETM_RST(cpu);
> +	} else {
> +		reg |= CPUCFG_CX_RST_CTRL_CX_RST(cpu); /* NEON */
> +	}
> +	writel(reg, cpucfg_base + CPUCFG_CX_RST_CTRL(cluster));
> +
> +	return 0;
> +}
> +
> +static int sunxi_cluster_powerup(unsigned int cluster)
> +{
> +	u32 reg;
> +
> +	pr_debug("%s: cluster %u\n", __func__, cluster);
> +	if (cluster >= SUNXI_NR_CLUSTERS)
> +		return -EINVAL;
> +
> +	/* assert ACINACTM */
> +	reg = readl(cpucfg_base + CPUCFG_CX_CTRL_REG1(cluster));
> +	reg |= CPUCFG_CX_CTRL_REG1_ACINACTM;
> +	writel(reg, cpucfg_base + CPUCFG_CX_CTRL_REG1(cluster));
> +
> +	/* assert cluster processor power-on resets */
> +	reg = readl(prcm_base + PRCM_CPU_PO_RST_CTRL(cluster));
> +	reg &= ~PRCM_CPU_PO_RST_CTRL_CORE_ALL;
> +	writel(reg, prcm_base + PRCM_CPU_PO_RST_CTRL(cluster));
> +
> +	/* assert cluster resets */
> +	reg = readl(cpucfg_base + CPUCFG_CX_RST_CTRL(cluster));
> +	reg &= ~CPUCFG_CX_RST_CTRL_DBG_SOC_RST;
> +	reg &= ~CPUCFG_CX_RST_CTRL_DBG_RST_ALL;
> +	reg &= ~CPUCFG_CX_RST_CTRL_H_RST;
> +	reg &= ~CPUCFG_CX_RST_CTRL_L2_RST;
> +
> +	/*
> +	 * Allwinner code also asserts resets for NEON on A15. According
> +	 * to ARM manuals, asserting power-on reset is sufficient.
> +	 */
> +	if (!(of_machine_is_compatible("allwinner,sun9i-a80") &&
> +			cluster == SUN9I_A80_A15_CLUSTER)) {
> +		reg &= ~CPUCFG_CX_RST_CTRL_ETM_RST_ALL;
> +	}
> +	writel(reg, cpucfg_base + CPUCFG_CX_RST_CTRL(cluster));
> +
> +	/* hold L1/L2 reset disable signals low */
> +	reg = readl(cpucfg_base + CPUCFG_CX_CTRL_REG0(cluster));
> +	if (of_machine_is_compatible("allwinner,sun9i-a80") &&
> +			cluster == SUN9I_A80_A15_CLUSTER) {
> +		/* Cortex-A15: hold L2RSTDISABLE low */
> +		reg &= ~CPUCFG_CX_CTRL_REG0_L2_RST_DISABLE_A15;
> +	} else {
> +		/* Cortex-A7: hold L1RSTDISABLE and L2RSTDISABLE low */
> +		reg &= ~CPUCFG_CX_CTRL_REG0_L1_RST_DISABLE_ALL;
> +		reg &= ~CPUCFG_CX_CTRL_REG0_L2_RST_DISABLE_A7;
> +	}
> +	writel(reg, cpucfg_base + CPUCFG_CX_CTRL_REG0(cluster));
> +
> +	/* clear cluster power gate */
> +	reg = readl(prcm_base + PRCM_PWROFF_GATING_REG(cluster));
> +	reg &= ~PRCM_PWROFF_GATING_REG_CLUSTER;
> +	writel(reg, prcm_base + PRCM_PWROFF_GATING_REG(cluster));
> +	udelay(20);
> +
> +	/* de-assert cluster resets */
> +	reg = readl(cpucfg_base + CPUCFG_CX_RST_CTRL(cluster));
> +	reg |= CPUCFG_CX_RST_CTRL_DBG_SOC_RST;
> +	reg |= CPUCFG_CX_RST_CTRL_H_RST;
> +	reg |= CPUCFG_CX_RST_CTRL_L2_RST;
> +	writel(reg, cpucfg_base + CPUCFG_CX_RST_CTRL(cluster));
> +
> +	/* de-assert ACINACTM */
> +	reg = readl(cpucfg_base + CPUCFG_CX_CTRL_REG1(cluster));
> +	reg &= ~CPUCFG_CX_CTRL_REG1_ACINACTM;
> +	writel(reg, cpucfg_base + CPUCFG_CX_CTRL_REG1(cluster));
> +
> +	return 0;
> +}
> +
> +static void sunxi_cpu_cache_disable(void)
> +{
> +	/* Disable and flush the local CPU cache. */
> +	v7_exit_coherency_flush(louis);
> +}
> +
> +/*
> + * This bit is shared between the initial mcpm_sync_init call to enable
> + * CCI-400 and proper cluster cache disable before power down.
> + */
> +static void sunxi_cluster_cache_disable_without_axi(void)
> +{
> +	if (read_cpuid_part() == 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"
> +		"isb\n"
> +		"dsb"
> +		: : "r" (0x400));
> +	}
> +
> +	/* Flush all cache levels for this cluster. */
> +	v7_exit_coherency_flush(all);
> +
> +	/*
> +	 * Disable cluster-level coherency by masking
> +	 * incoming snoops and DVM messages:
> +	 */
> +	cci_disable_port_by_cpu(read_cpuid_mpidr());
> +}
> +
> +static void sunxi_cluster_cache_disable(void)
> +{
> +	unsigned int cluster = MPIDR_AFFINITY_LEVEL(read_cpuid_mpidr(), 1);
> +	u32 reg;
> +
> +	pr_info("%s: cluster %u\n", __func__, cluster);
> +
> +	sunxi_cluster_cache_disable_without_axi();
> +
> +	/* last man standing, assert ACINACTM */
> +	reg = readl(cpucfg_base + CPUCFG_CX_CTRL_REG1(cluster));
> +	reg |= CPUCFG_CX_CTRL_REG1_ACINACTM;
> +	writel(reg, cpucfg_base + CPUCFG_CX_CTRL_REG1(cluster));
> +}
> +
> +static const struct mcpm_platform_ops sunxi_power_ops = {
> +	.cpu_powerup		= sunxi_cpu_powerup,
> +	.cluster_powerup	= sunxi_cluster_powerup,
> +	.cpu_cache_disable	= sunxi_cpu_cache_disable,
> +	.cluster_cache_disable	= sunxi_cluster_cache_disable,
> +};
> +
> +/*
> + * Enable cluster-level coherency, in preparation for turning on the MMU.
> + *
> + * Also enable regional clock gating and L2 data latency settings for
> + * Cortex-A15.
> + */
> +static void __naked sunxi_power_up_setup(unsigned int affinity_level)
> +{
> +	asm volatile (
> +		"mrc	p15, 0, r1, c0, c0, 0\n"
> +		"movw	r2, #" __stringify(ARM_CPU_PART_MASK & 0xffff) "\n"
> +		"movt	r2, #" __stringify(ARM_CPU_PART_MASK >> 16) "\n"
> +		"and	r1, r1, r2\n"
> +		"movw	r2, #" __stringify(ARM_CPU_PART_CORTEX_A15 & 0xffff) "\n"
> +		"movt	r2, #" __stringify(ARM_CPU_PART_CORTEX_A15 >> 16) "\n"
> +		"cmp	r1, r2\n"
> +		"bne	not_a15\n"
> +
> +		/* The following is Cortex-A15 specific */
> +
> +		/* L2CTRL: Enable CPU regional clock gates */
> +		"mrc p15, 1, r1, c15, c0, 4\n"
> +		"orr r1, r1, #(0x1<<31)\n"
> +		"mcr p15, 1, r1, c15, c0, 4\n"
> +
> +		/* L2ACTLR */
> +		"mrc p15, 1, r1, c15, c0, 0\n"
> +		/* Enable L2, GIC, and Timer regional clock gates */
> +		"orr r1, r1, #(0x1<<26)\n"
> +		/* Disable clean/evict from being pushed to external */
> +		"orr r1, r1, #(0x1<<3)\n"
> +		"mcr p15, 1, r1, c15, c0, 0\n"
> +
> +		/* L2 data RAM latency */
> +		"mrc p15, 1, r1, c9, c0, 2\n"
> +		"bic r1, r1, #(0x7<<0)\n"
> +		"orr r1, r1, #(0x3<<0)\n"
> +		"mcr p15, 1, r1, c9, c0, 2\n"
> +
> +		/* End of Cortex-A15 specific setup */
> +		"not_a15:\n"
> +
> +		"cmp	r0, #1\n"
> +		"bxne	lr\n"
> +		"b	cci_enable_port_for_self"
> +	);
> +}
> +
> +static void sunxi_mcpm_setup_entry_point(void)
> +{
> +	__raw_writel(virt_to_phys(mcpm_entry_point),
> +		     prcm_base + PRCM_CPU_SOFT_ENTRY_REG);
> +}
> +
> +static int __init sunxi_mcpm_init(void)
> +{
> +	struct device_node *node;
> +	int ret;
> +
> +	if (!of_machine_is_compatible("allwinner,sun9i-a80"))
> +		return -ENODEV;
> +
> +	if (!cci_probed())
> +		return -ENODEV;
> +
> +	node = of_find_compatible_node(NULL, NULL,
> +			"allwinner,sun9i-a80-cpucfg");
> +	if (!node)
> +		return -ENODEV;
> +
> +	cpucfg_base = of_iomap(node, 0);
> +	of_node_put(node);
> +	if (!cpucfg_base) {
> +		pr_err("%s: failed to map CPUCFG registers\n", __func__);
> +		return -ENOMEM;
> +	}

Can't we request the region as well?

> +
> +	node = of_find_compatible_node(NULL, NULL,
> +			"allwinner,sun9i-a80-prcm");
> +	if (!node)
> +		return -ENODEV;
> +
> +	prcm_base = of_iomap(node, 0);
> +
> +	of_node_put(node);
> +	if (!prcm_base) {
> +		pr_err("%s: failed to map PRCM registers\n", __func__);
> +		iounmap(prcm_base);
> +		return -ENOMEM;
> +	}
> +
> +	ret = mcpm_platform_register(&sunxi_power_ops);
> +	if (!ret)
> +		ret = mcpm_sync_init(sunxi_power_up_setup);
> +	if (!ret)
> +		/* do not disable AXI master as no one will re-enable it */
> +		ret = mcpm_loopback(sunxi_cluster_cache_disable_without_axi);
> +	if (ret) {
> +		iounmap(cpucfg_base);
> +		iounmap(prcm_base);
> +		return ret;
> +	}
> +
> +	mcpm_smp_set_ops();
> +
> +	pr_info("sunxi MCPM support installed\n");
> +
> +	sunxi_mcpm_setup_entry_point();
> +
> +	return ret;
> +}

It looks mostly good, and I would replace the sunxi by sun9i, and call
that file sun9i-mcpm.c

Thanks!
Maxime

-- 
Maxime Ripard, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com

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