[PATCH 3/5] sysreset: provide SBI based sysreset driver

[Sean Anderson <seanga2@gmail.com>]

On 3/4/21 12:00 PM, Heinrich Schuchardt wrote:
> Provide sysreset driver using the SBI system reset extension.
> 
> Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
> ---
>   MAINTAINERS                     |   1 +
>   arch/riscv/include/asm/sbi.h    |   1 +
>   arch/riscv/lib/sbi.c            |  21 +++++--
>   drivers/sysreset/Kconfig        |  11 ++++
>   drivers/sysreset/Makefile       |   1 +
>   drivers/sysreset/sysreset_sbi.c | 102 ++++++++++++++++++++++++++++++++
>   lib/efi_loader/Kconfig          |   2 +-
>   7 files changed, 134 insertions(+), 5 deletions(-)
>   create mode 100644 drivers/sysreset/sysreset_sbi.c
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index de499940e5..192db06ff9 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -985,6 +985,7 @@ T:	git https://source.denx.de/u-boot/custodians/u-boot-riscv.git
>   F:	arch/riscv/
>   F:	cmd/riscv/
>   F:	doc/usage/sbi.rst
> +F:	drivers/sysreset/sysreset_sbi.c
>   F:	drivers/timer/andes_plmt_timer.c
>   F:	drivers/timer/sifive_clint_timer.c
>   F:	tools/prelink-riscv.c
> diff --git a/arch/riscv/include/asm/sbi.h b/arch/riscv/include/asm/sbi.h
> index c598bb11ce..058e2e23a8 100644
> --- a/arch/riscv/include/asm/sbi.h
> +++ b/arch/riscv/include/asm/sbi.h
> @@ -150,5 +150,6 @@ void sbi_set_timer(uint64_t stime_value);
>   long sbi_get_spec_version(void);
>   int sbi_get_impl_id(void);
>   int sbi_probe_extension(int ext);
> +void sbi_srst_reset(unsigned long type, unsigned long reason);
> 
>   #endif
> diff --git a/arch/riscv/lib/sbi.c b/arch/riscv/lib/sbi.c
> index 77845a73ca..8508041f2a 100644
> --- a/arch/riscv/lib/sbi.c
> +++ b/arch/riscv/lib/sbi.c
> @@ -8,13 +8,14 @@
>    */
> 
>   #include <common.h>
> +#include <efi_loader.h>
>   #include <asm/encoding.h>
>   #include <asm/sbi.h>
> 
> -struct sbiret sbi_ecall(int ext, int fid, unsigned long arg0,
> -			unsigned long arg1, unsigned long arg2,
> -			unsigned long arg3, unsigned long arg4,
> -			unsigned long arg5)
> +struct sbiret __efi_runtime sbi_ecall(int ext, int fid, unsigned long arg0,
> +				      unsigned long arg1, unsigned long arg2,
> +				      unsigned long arg3, unsigned long arg4,
> +				      unsigned long arg5)
>   {
>   	struct sbiret ret;
> 
> @@ -108,6 +109,18 @@ int sbi_probe_extension(int extid)
>   	return -ENOTSUPP;
>   }
> 
> +/**
> + * sbi_srst_reset() - invoke system reset extension
> + *
> + * @type:	type of reset
> + * @reason:	reason for reset
> + */
> +void __efi_runtime sbi_srst_reset(unsigned long type, unsigned long reason)
> +{
> +	sbi_ecall(SBI_EXT_SRST, SBI_EXT_SRST_RESET, type, reason,
> +		  0, 0, 0, 0);
> +}
> +
>   #ifdef CONFIG_SBI_V01
> 
>   /**
> diff --git a/drivers/sysreset/Kconfig b/drivers/sysreset/Kconfig
> index 0e5c7c9971..05a7e26300 100644
> --- a/drivers/sysreset/Kconfig
> +++ b/drivers/sysreset/Kconfig
> @@ -79,6 +79,17 @@ config SYSRESET_PSCI
>   	  Enable PSCI SYSTEM_RESET function call.  To use this, PSCI firmware
>   	  must be running on your system.
> 
> +config SYSRESET_SBI
> +	bool "Enable support for SBI System Reset"
> +	depends on RISCV_SMODE && SBI_V02
> +	select SYSRESET_CMD_POWEROFF if CMD_POWEROFF
> +	help
> +	  Enable system reset and poweroff via the SBI system reset extension.
> +	  If the SBI implemention provides the extension, is board specific.
> +	  The extension was introduced in version 0.3 of the SBI specification.
> +	  The SBI system reset driver supports the UEFI ResetSystem() service
> +	  at runtime.
> +
>   config SYSRESET_SOCFPGA
>   	bool "Enable support for Intel SOCFPGA family"
>   	depends on ARCH_SOCFPGA && (TARGET_SOCFPGA_GEN5 || TARGET_SOCFPGA_ARRIA10)
> diff --git a/drivers/sysreset/Makefile b/drivers/sysreset/Makefile
> index de81c399d7..8e00be0779 100644
> --- a/drivers/sysreset/Makefile
> +++ b/drivers/sysreset/Makefile
> @@ -13,6 +13,7 @@ obj-$(CONFIG_SYSRESET_MPC83XX) += sysreset_mpc83xx.o
>   obj-$(CONFIG_SYSRESET_MICROBLAZE) += sysreset_microblaze.o
>   obj-$(CONFIG_SYSRESET_OCTEON) += sysreset_octeon.o
>   obj-$(CONFIG_SYSRESET_PSCI) += sysreset_psci.o
> +obj-$(CONFIG_SYSRESET_SBI) += sysreset_sbi.o
>   obj-$(CONFIG_SYSRESET_SOCFPGA) += sysreset_socfpga.o
>   obj-$(CONFIG_SYSRESET_SOCFPGA_SOC64) += sysreset_socfpga_soc64.o
>   obj-$(CONFIG_SYSRESET_TI_SCI) += sysreset-ti-sci.o
> diff --git a/drivers/sysreset/sysreset_sbi.c b/drivers/sysreset/sysreset_sbi.c
> new file mode 100644
> index 0000000000..87fbc3ea3e
> --- /dev/null
> +++ b/drivers/sysreset/sysreset_sbi.c
> @@ -0,0 +1,102 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * Copyright 2021, Heinrich Schuchardt <xypron.glpk@gmx.de>
> + */
> +
> +#include <common.h>
> +#include <dm.h>
> +#include <errno.h>
> +#include <efi_loader.h>
> +#include <log.h>
> +#include <sysreset.h>
> +#include <asm/sbi.h>
> +
> +static long __efi_runtime_data have_reset;
> +
> +static int sbi_sysreset_request(struct udevice *dev, enum sysreset_t type)
> +{
> +	enum sbi_srst_reset_type reset_type;
> +
> +	if (!have_reset)
> +		return -ENOENT;

Is this necessary? This should never be called if there is no reset,
since we just fail to probe.

> +
> +	switch (type) {
> +	case SYSRESET_WARM:
> +		reset_type = SBI_SRST_RESET_TYPE_WARM_REBOOT;
> +		break;
> +	case SYSRESET_COLD:
> +		reset_type = SBI_SRST_RESET_TYPE_COLD_REBOOT;
> +		break;
> +	case SYSRESET_POWER_OFF:
> +		reset_type = SBI_SRST_RESET_TYPE_SHUTDOWN;
> +		break;
> +	default:
> +		log_err("SBI has no system reset extension\n");
> +		return -ENOSYS;
> +	}
> +
> +	sbi_srst_reset(reset_type, SBI_SRST_RESET_REASON_NONE);
> +
> +	return -EINPROGRESS;
> +}
> +
> +efi_status_t efi_reset_system_init(void)
> +{
> +	return EFI_SUCCESS;
> +}
> +
> +void __efi_runtime EFIAPI efi_reset_system(enum efi_reset_type type,
> +					   efi_status_t reset_status,
> +					   unsigned long data_size,
> +					   void *reset_data)

As an aside, is there a reason why the generic (weak) efi_reset_system
does not just call sysreset_walk_halt(type)?

> +{
> +	enum sbi_srst_reset_type reset_type;
> +
> +	if (have_reset)
> +		switch (type) {
> +		case SYSRESET_WARM:
> +			reset_type = SBI_SRST_RESET_TYPE_WARM_REBOOT;
> +			break;
> +		case SYSRESET_COLD:
> +			reset_type = SBI_SRST_RESET_TYPE_COLD_REBOOT;
> +			break;
> +		case SYSRESET_POWER_OFF:
> +			reset_type = SBI_SRST_RESET_TYPE_SHUTDOWN;
> +			break;
> +		default:
> +			goto hang;

Why do we hang by default? For comparison, sysreset_x86 has

	if (reset_type == EFI_RESET_COLD ||
		 reset_type == EFI_RESET_PLATFORM_SPECIFIC)
		value = SYS_RST | RST_CPU | FULL_RST;
	else /* assume EFI_RESET_WARM since we cannot return an error */
		value = SYS_RST | RST_CPU;

> +	}
> +
> +	sbi_srst_reset(reset_type, SBI_SRST_RESET_REASON_NONE);

Should we instead do

	enum sbi_srst_reset_reason reset_reason;
	if (reset_status == EFI_SUCCESS)
		reset_reason = SBI_SRST_RESET_REASON_NONE;
	else
		reset_reason = SBI_SRST_RESET_REASON_SYS_FAILURE;
	sbi_srst_reset(reset_type, reset_status == EFI_SUCCESS ? SBI_SRST_RESET_REASON_NONE : SBI_SRST_RESET_REASON_SYS_FAILURE);

since we have reset status available?

> +
> +hang:
> +	while (1)
> +		;
> +}
> +
> +static int sbi_sysreset_probe(struct udevice *dev)
> +{
> +	have_reset = sbi_probe_extension(SBI_EXT_SRST);
> +	if (have_reset)
> +		return 0;
> +
> +	log_err("SBI has no system reset extension\n");

Is this an error? It's perfectly normal for SBI implementations to lack
support for some extensions. Perhaps a warning/info would be better.

> +	return -ENOENT;
> +}
> +
> +static const struct udevice_id sbi_sysreset_ids[] = {
> +	{ .compatible = "riscv" },

This compatible string is already in-use for RISC-V CPUs. And if this
isn't supposed to have a device tree binding, do we even need of_match?

> +	{ }
> +};
> +
> +static struct sysreset_ops sbi_sysreset_ops = {
> +	.request = sbi_sysreset_request,
> +};
> +
> +U_BOOT_DRIVER(sbi_sysreset) = {
> +	.name = "sbi-sysreset",
> +	.id = UCLASS_SYSRESET,
> +	.of_match = sbi_sysreset_ids,
> +	.ops = &sbi_sysreset_ops,
> +	.probe = sbi_sysreset_probe,
> +};
> diff --git a/lib/efi_loader/Kconfig b/lib/efi_loader/Kconfig
> index e729f727df..7e76435339 100644
> --- a/lib/efi_loader/Kconfig
> +++ b/lib/efi_loader/Kconfig
> @@ -277,7 +277,7 @@ config EFI_HAVE_RUNTIME_RESET
>   	bool
>   	default y
>   	depends on ARCH_BCM283X || FSL_LAYERSCAPE || PSCI_RESET || \
> -		   SANDBOX || SYSRESET_X86
> +		   SANDBOX || SYSRESET_SBI || SYSRESET_X86

As a general note, perhaps it is better to set this from other Kconfigs?
How long will this list get?

--Sean

> 
>   config EFI_GRUB_ARM32_WORKAROUND
>   	bool "Workaround for GRUB on 32bit ARM"
> --
> 2.30.1
>