The SBI SRST extension provides a standard way to poweroff and reboot the system irrespective to whether Linux RISC-V S-mode is running natively (HS-mode) or inside Guest/VM (VS-mode).
The draft specification of SBI SRST extension is available in srbt_v1 branch of: https://github.com/avpatel/riscv-sbi-doc. This patch extends Linux RISC-V SBI implementation to detect and use SBI SRST extension. Signed-off-by: Anup Patel <[email protected]> --- Changes since v1: - Updated patch as-per latest SBI SRST extension draft spec where we have only one SBI call with "reset_type" parameter --- arch/riscv/include/asm/sbi.h | 11 +++++++++++ arch/riscv/kernel/sbi.c | 30 ++++++++++++++++++++++++++++++ 2 files changed, 41 insertions(+) diff --git a/arch/riscv/include/asm/sbi.h b/arch/riscv/include/asm/sbi.h index 653edb25d495..6ae1288d9c7e 100644 --- a/arch/riscv/include/asm/sbi.h +++ b/arch/riscv/include/asm/sbi.h @@ -27,6 +27,7 @@ enum sbi_ext_id { SBI_EXT_IPI = 0x735049, SBI_EXT_RFENCE = 0x52464E43, SBI_EXT_HSM = 0x48534D, + SBI_EXT_SRST = 0x53525354, }; enum sbi_ext_base_fid { @@ -70,6 +71,16 @@ enum sbi_hsm_hart_status { SBI_HSM_HART_STATUS_STOP_PENDING, }; +enum sbi_ext_srst_fid { + SBI_EXT_SRST_RESET = 0, +}; + +enum sbi_srst_reset_type { + SBI_SRST_RESET_TYPE_SHUTDOWN = 0, + SBI_SRST_RESET_TYPE_COLD_REBOOT, + SBI_SRST_RESET_TYPE_WARM_REBOOT, +}; + #define SBI_SPEC_VERSION_DEFAULT 0x1 #define SBI_SPEC_VERSION_MAJOR_SHIFT 24 #define SBI_SPEC_VERSION_MAJOR_MASK 0x7f diff --git a/arch/riscv/kernel/sbi.c b/arch/riscv/kernel/sbi.c index 226ccce0f9e0..18c27f1f8cf2 100644 --- a/arch/riscv/kernel/sbi.c +++ b/arch/riscv/kernel/sbi.c @@ -7,6 +7,7 @@ #include <linux/init.h> #include <linux/pm.h> +#include <linux/reboot.h> #include <asm/sbi.h> #include <asm/smp.h> @@ -501,6 +502,28 @@ int sbi_remote_hfence_vvma_asid(const unsigned long *hart_mask, } EXPORT_SYMBOL(sbi_remote_hfence_vvma_asid); +static void sbi_srst_reset(unsigned long type) +{ + sbi_ecall(SBI_EXT_SRST, SBI_EXT_SRST_RESET, type, 0, 0, 0, 0, 0); + pr_warn("%s: reset_type=%ld failed\n", __func__, type); +} + +static int sbi_srst_reboot(struct notifier_block *this, + unsigned long mode, void *cmd) +{ + sbi_srst_reset((mode == REBOOT_WARM || mode == REBOOT_SOFT) ? + SBI_SRST_RESET_TYPE_WARM_REBOOT : + SBI_SRST_RESET_TYPE_COLD_REBOOT); + return NOTIFY_DONE; +} + +static struct notifier_block sbi_srst_reboot_nb; + +static void sbi_srst_power_off(void) +{ + sbi_srst_reset(SBI_SRST_RESET_TYPE_SHUTDOWN); +} + /** * sbi_probe_extension() - Check if an SBI extension ID is supported or not. * @extid: The extension ID to be probed. @@ -593,6 +616,13 @@ int __init sbi_init(void) } else { __sbi_rfence = __sbi_rfence_v01; } + if (sbi_probe_extension(SBI_EXT_SRST) > 0) { + pr_info("SBI v0.2 SRST extension detected\n"); + pm_power_off = sbi_srst_power_off; + sbi_srst_reboot_nb.notifier_call = sbi_srst_reboot; + sbi_srst_reboot_nb.priority = 192; + register_restart_handler(&sbi_srst_reboot_nb); + } } else { __sbi_set_timer = __sbi_set_timer_v01; __sbi_send_ipi = __sbi_send_ipi_v01; -- 2.25.1
