supervisor: Add an example on the HSM extension

The HSM extension from SBI v2.0 allows a supervisor to manage the state
of harts on the system. Moreover, it also guarantees that only one hart
makes it into the booting stages of the supervisor, and it's up to the
supervisor to wake up the rest through the HSM extension.

I have added an example which showcases this extension in different
ways, and it finally shuts down the machine.

Signed-off-by: Miquel Sabaté Solà <mikisabate@gmail.com>

1 files changed, 73 insertions, 0 deletions

diff --git a/arch/riscv/supervisor/hsm/sbi.h b/arch/riscv/supervisor/hsm/sbi.h
new file mode 100644
index 0000000..7891f76
--- /dev/null
+++ b/arch/riscv/supervisor/hsm/sbi.h
@@ -0,0 +1,73 @@
+#ifndef __SBI_H__
+#define __SBI_H__
+
+enum sbi_ret_error {
+	SBI_SUCCESS = 0,
+	SBI_ERR_FAILED = -1,
+	SBI_ERR_NOT_SUPPORTED = -2,
+	SBI_ERR_INVALID_PARAM = -3,
+	SBI_ERR_DENIED = -4,
+	SBI_ERR_INVALID_ADDRESS = -5,
+	SBI_ERR_ALREADY_AVAILABLE = -6,
+	SBI_ERR_ALREADY_STARTED = -7,
+	SBI_ERR_ALREADY_STOPPED = -8,
+	SBI_ERR_NO_SHMEM = -9,
+};
+
+enum sbi_ext {
+	HSM_EXT = 0x0048534D,
+	DBCN_EXT = 0x4442434E,
+	SRST_EXT = 0x53525354,
+};
+
+enum hsm_actions {
+	HSM_HART_START = 0x00,
+	HSM_HART_STOP = 0x01,
+	HSM_HART_GET_STATUS = 0x02,
+	HSM_HART_SUSPEND = 0x03,
+};
+
+enum hsm_states {
+	HSM_HART_STARTED = 0,
+	HSM_HART_STOPPED = 1,
+	HSM_HART_START_PENDING = 2,
+	HSM_HART_STOP_PENDING = 3,
+	HSM_HART_SUSPENDED = 4,
+	HSM_HART_SUSPEND_PENDING = 5,
+	HSM_HART_RESUME_PENDING = 6,
+};
+
+enum dbcn_actions {
+	DBCN_WRITE = 0x00,
+};
+
+enum srst_actions {
+	SRST_RESET = 0,
+};
+
+enum srst_type {
+	SRST_SHUTDOWN = 0,
+	SRST_COLD_REBOOT = 1,
+	SRST_WARM_REBOOT = 2,
+};
+
+enum srst_reason {
+	SRST_NO_REASON = 0,
+	SRST_SYS_FAILURE = 1,
+};
+
+struct sbi_ret {
+	long error;
+	long value;
+};
+
+struct sbi_ret __sbi_ecall(unsigned long arg0, unsigned long arg1, unsigned long arg2,
+						   unsigned long arg3, unsigned long arg4, unsigned long arg5, int fid,
+						   int ext);
+
+#define sbi_ecall0(ext, fid) __sbi_ecall(0, 0, 0, 0, 0, 0, fid, ext)
+#define sbi_ecall1(ext, fid, arg0) __sbi_ecall(arg0, 0, 0, 0, 0, 0, fid, ext)
+#define sbi_ecall2(ext, fid, arg0, arg1) __sbi_ecall(arg0, arg1, 0, 0, 0, 0, fid, ext)
+#define sbi_ecall3(ext, fid, arg0, arg1, arg2) __sbi_ecall(arg0, arg1, arg2, 0, 0, 0, fid, ext)
+
+#endif // __SBI_H__