lib: sbi: Add system suspend skeleton

Add the SUSP extension probe and ecall support, but for now the
system suspend function is just a stub.

Signed-off-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Anup Patel <anup@brainfault.org>

lib/sbi/Kconfig

@@ -22,6 +22,10 @@ config SBI_ECALL_SRST
 	bool "System Reset extension"
 	default y
 
+config SBI_ECALL_SUSP
+	bool "System Suspend extension"
+	default y
+
 config SBI_ECALL_PMU
 	bool "Performance Monitoring Unit extension"
 	default y

lib/sbi/objects.mk

@@ -34,6 +34,9 @@ libsbi-objs-$(CONFIG_SBI_ECALL_HSM) += sbi_ecall_hsm.o
 carray-sbi_ecall_exts-$(CONFIG_SBI_ECALL_SRST) += ecall_srst
 libsbi-objs-$(CONFIG_SBI_ECALL_SRST) += sbi_ecall_srst.o
 
+carray-sbi_ecall_exts-$(CONFIG_SBI_ECALL_SUSP) += ecall_susp
+libsbi-objs-$(CONFIG_SBI_ECALL_SUSP) += sbi_ecall_susp.o
+
 carray-sbi_ecall_exts-$(CONFIG_SBI_ECALL_PMU) += ecall_pmu
 libsbi-objs-$(CONFIG_SBI_ECALL_PMU) += sbi_ecall_pmu.o
 

lib/sbi/sbi_ecall_susp.c

@@ -0,0 +1,48 @@
+// SPDX-License-Identifier: BSD-2-Clause
+#include <sbi/sbi_ecall.h>
+#include <sbi/sbi_ecall_interface.h>
+#include <sbi/sbi_error.h>
+#include <sbi/sbi_trap.h>
+#include <sbi/sbi_system.h>
+
+static int sbi_ecall_susp_handler(unsigned long extid, unsigned long funcid,
+				  const struct sbi_trap_regs *regs,
+				  unsigned long *out_val,
+				  struct sbi_trap_info *out_trap)
+{
+	int ret = SBI_ENOTSUPP;
+
+	if (funcid == SBI_EXT_SUSP_SUSPEND)
+		ret = sbi_system_suspend(regs->a0, regs->a1, regs->a2);
+
+	if (ret >= 0) {
+		*out_val = ret;
+		ret = 0;
+	}
+
+	return ret;
+}
+
+static int sbi_ecall_susp_probe(unsigned long extid, unsigned long *out_val)
+{
+	u32 type, count = 0;
+
+	/*
+	 * At least one suspend type should be supported by the
+	 * platform for the SBI SUSP extension to be usable.
+	 */
+	for (type = 0; type <= SBI_SUSP_SLEEP_TYPE_LAST; type++) {
+		if (sbi_system_suspend_supported(type))
+			count++;
+	}
+
+	*out_val = count ? 1 : 0;
+	return 0;
+}
+
+struct sbi_ecall_extension ecall_susp = {
+	.extid_start = SBI_EXT_SUSP,
+	.extid_end = SBI_EXT_SUSP,
+	.handle = sbi_ecall_susp_handler,
+	.probe = sbi_ecall_susp_probe,
+};

lib/sbi/sbi_init.c

@@ -69,6 +69,7 @@ static void sbi_boot_print_general(struct sbi_scratch *scratch)
 	const struct sbi_timer_device *tdev;
 	const struct sbi_console_device *cdev;
 	const struct sbi_system_reset_device *srdev;
+	const struct sbi_system_suspend_device *susp_dev;
 	const struct sbi_platform *plat = sbi_platform_ptr(scratch);
 
 	if (scratch->options & SBI_SCRATCH_NO_BOOT_PRINTS)
@@ -103,6 +104,9 @@ static void sbi_boot_print_general(struct sbi_scratch *scratch)
 	srdev = sbi_system_reset_get_device(SBI_SRST_RESET_TYPE_SHUTDOWN, 0);
 	sbi_printf("Platform Shutdown Device  : %s\n",
 		   (srdev) ? srdev->name : "---");
+	susp_dev = sbi_system_suspend_get_device();
+	sbi_printf("Platform Suspend Device   : %s\n",
+		   (susp_dev) ? susp_dev->name : "---");
 
 	/* Firmware details */
 	sbi_printf("Firmware Base             : 0x%lx\n", scratch->fw_start);

lib/sbi/sbi_system.c

@@ -92,3 +92,29 @@ void __noreturn sbi_system_reset(u32 reset_type, u32 reset_reason)
 	/* If platform specific reset did not work then do sbi_exit() */
 	sbi_exit(scratch);
 }
+
+static const struct sbi_system_suspend_device *suspend_dev = NULL;
+
+const struct sbi_system_suspend_device *sbi_system_suspend_get_device(void)
+{
+	return suspend_dev;
+}
+
+void sbi_system_suspend_set_device(struct sbi_system_suspend_device *dev)
+{
+	if (!dev || suspend_dev)
+		return;
+
+	suspend_dev = dev;
+}
+
+bool sbi_system_suspend_supported(u32 sleep_type)
+{
+	return suspend_dev && suspend_dev->system_suspend_check &&
+	       suspend_dev->system_suspend_check(sleep_type);
+}
+
+int sbi_system_suspend(u32 sleep_type, ulong resume_addr, ulong opaque)
+{
+	return 0;
+}