[U-Boot] [PATCHv6 5/6] ARMv8/PSCI: Fixup the device tree for PSCI

[york sun]

On 06/21/2016 08:42 PM, Zhiqiang Hou wrote:
> From: Hou Zhiqiang <Zhiqiang.Hou at nxp.com>
>
> Set the enable-method in the cpu node to PSCI, and create device
> node for PSCI, when PSCI was enabled.
>
> Signed-off-by: Hou Zhiqiang <Zhiqiang.Hou at nxp.com>
> ---
> V6:
>   - Removed PSCI version 0.1 support.
>
> V5:
>   - Moved the weak func sec_firmware_support_psci_version to sec_firmware.c.
>   - Correct the PSCI version value in switch-case. The right version format is marjor[31:16]:minor[15:0].
>
>   arch/arm/cpu/armv8/Makefile |   1 +
>   arch/arm/cpu/armv8/cpu-dt.c | 122 ++++++++++++++++++++++++++++++++++++++++++++
>   arch/arm/lib/bootm-fdt.c    |   2 +-
>   3 files changed, 124 insertions(+), 1 deletion(-)
>   create mode 100644 arch/arm/cpu/armv8/cpu-dt.c
>
> diff --git a/arch/arm/cpu/armv8/Makefile b/arch/arm/cpu/armv8/Makefile
> index ee9e009..33e6db0 100644
> --- a/arch/arm/cpu/armv8/Makefile
> +++ b/arch/arm/cpu/armv8/Makefile
> @@ -15,6 +15,7 @@ obj-y	+= cache.o
>   obj-y	+= tlb.o
>   obj-y	+= transition.o
>   obj-y	+= fwcall.o
> +obj-y	+= cpu-dt.o
>   obj-$(CONFIG_ARMV8_SEC_FIRMWARE_SUPPORT) += sec_firmware.o sec_firmware_asm.o
>
>   obj-$(CONFIG_FSL_LAYERSCAPE) += fsl-layerscape/
> diff --git a/arch/arm/cpu/armv8/cpu-dt.c b/arch/arm/cpu/armv8/cpu-dt.c
> new file mode 100644
> index 0000000..6b9aa77
> --- /dev/null
> +++ b/arch/arm/cpu/armv8/cpu-dt.c
> @@ -0,0 +1,122 @@
> +/*
> + * Copyright 2016 NXP Semiconductor, Inc.
> + *
> + * SPDX-License-Identifier:	GPL-2.0+
> + */
> +
> +#include <common.h>
> +#include <libfdt.h>
> +#include <fdt_support.h>
> +#include <linux/sizes.h>
> +#include <linux/kernel.h>
> +#ifdef CONFIG_ARMV8_SEC_FIRMWARE_SUPPORT
> +#include <asm/armv8/sec_firmware.h>
> +#endif
> +
> +#ifdef CONFIG_MP
> +DECLARE_GLOBAL_DATA_PTR;
> +
> +#if defined(CONFIG_ARMV8_PSCI)
> +static int cpu_update_dt_psci(void *fdt)
> +{
> +	int nodeoff;
> +	unsigned int psci_ver;
> +	char *psci_compt;
> +	int tmp;
> +
> +	nodeoff = fdt_path_offset(fdt, "/cpus");
> +	if (nodeoff < 0) {
> +		printf("couldn't find /cpus\n");
> +		return nodeoff;
> +	}
> +
> +	/* add 'enable-method = "psci"' to each cpu node */
> +	for (tmp = fdt_first_subnode(fdt, nodeoff);
> +	     tmp >= 0;
> +	     tmp = fdt_next_subnode(fdt, tmp)) {
> +		const struct fdt_property *prop;
> +		int len;
> +
> +		prop = fdt_get_property(fdt, tmp, "device_type", &len);
> +		if (!prop)
> +			continue;
> +		if (len < 4)
> +			continue;
> +		if (strcmp(prop->data, "cpu"))
> +			continue;
> +
> +		/*
> +		 * Not checking rv here, our approach is to skip over errors in
> +		 * individual cpu nodes, hopefully some of the nodes are
> +		 * processed correctly and those will boot
> +		 */
> +		fdt_setprop_string(fdt, tmp, "enable-method", "psci");
> +	}
> +
> +	/*
> +	 * The PSCI node might be called "/psci" or might be called something
> +	 * else but contain either of the compatible strings
> +	 * "arm,psci"/"arm,psci-0.2"
> +	 */
> +	nodeoff = fdt_path_offset(fdt, "/psci");
> +	if (nodeoff >= 0)
> +		goto init_psci_node;
> +
> +	nodeoff = fdt_node_offset_by_compatible(fdt, -1, "arm,psci");
> +	if (nodeoff >= 0)
> +		goto init_psci_node;
> +
> +	nodeoff = fdt_node_offset_by_compatible(fdt, -1, "arm,psci-0.2");
> +	if (nodeoff >= 0)
> +		goto init_psci_node;
> +
> +	nodeoff = fdt_node_offset_by_compatible(fdt, -1, "arm,psci-1.0");
> +	if (nodeoff >= 0)
> +		goto init_psci_node;
> +
> +	nodeoff = fdt_path_offset(fdt, "/");
> +	if (nodeoff < 0)
> +		return nodeoff;
> +
> +	nodeoff = fdt_add_subnode(fdt, nodeoff, "psci");
> +	if (nodeoff < 0)
> +		return nodeoff;
> +
> +init_psci_node:
> +#ifdef CONFIG_ARMV8_SEC_FIRMWARE_SUPPORT
> +	psci_ver = sec_firmware_support_psci_version();
> +#endif
> +	switch (psci_ver) {
> +	case 0x00010000:
> +		psci_compt = "arm,psci-1.0";
> +		break;
> +	case 0x00000002:
> +		psci_compt = "arm,psci-0.2";
> +		break;
> +	default:
> +		psci_compt = "arm,psci-0.2";
> +		break;
> +	}
> +
> +	tmp = fdt_setprop_string(fdt, nodeoff, "compatible", psci_compt);
> +	if (tmp)
> +		return tmp;
> +
> +	tmp = fdt_setprop_string(fdt, nodeoff, "method", "smc");
> +	if (tmp)
> +		return tmp;
> +
> +	return 0;
> +}
> +#endif
> +#endif
> +
> +int psci_update_dt(void *fdt)
> +{
> +#ifdef CONFIG_MP
> +#if defined(CONFIG_ARMV8_PSCI)
> +	cpu_update_dt_psci(fdt);
> +#endif
> +#endif
> +	return 0;
> +}
> diff --git a/arch/arm/lib/bootm-fdt.c b/arch/arm/lib/bootm-fdt.c
> index 7677358..c642ff8 100644
> --- a/arch/arm/lib/bootm-fdt.c
> +++ b/arch/arm/lib/bootm-fdt.c
> @@ -42,7 +42,7 @@ int arch_fixup_fdt(void *blob)
>   	}
>
>   	ret = fdt_fixup_memory_banks(blob, start, size, CONFIG_NR_DRAM_BANKS);
> -#ifdef CONFIG_ARMV7_NONSEC
> +#if defined(CONFIG_ARMV7_NONSEC) || defined(CONFIG_ARMV8_PSCI)
>   	if (ret)
>   		return ret;
>
>

As far as CONFIG_ARMV8_PSCI is defined, psci_update_dt(blob) is called. 
Regardless if ppa is running, the psci node is always created and cpu 
boot method is always updated with "psci". Then previous patch (4th in 
this set) detects psci version. If it is 0xffffffff, psci node is 
removed, and cpu boot method is updated again with spin-table. Do I 
understand your flow correctly?

If my understand is correct, I suggest to add a check of psci_version 
before calling cpu_update_dt_psci(fdt). It avoids unnecessary setting 
and helps to understand the flow.

York