[PATCH] lib: sbi: Align system suspend errors with spec

[Andrew Jones]

The spec says sbi_system_suspend() will return SBI_ERR_INVALID_PARAM
when "sleep_type is reserved or is platform-specific and unimplemented"
and SBI_ERR_NOT_SUPPORTED when sleep_type "is not reserved and is
implemented, but the platform does not support it due to one or more
missing dependencies." Ensure SBI_ERR_INVALID_PARAM is returned for
reserved sleep types and that the system suspend driver can choose
which of the two error types to return itself by returning an error
from its check function rather than a boolean.

Signed-off-by: Andrew Jones <ajones at ventanamicro.com>
---
 include/sbi/sbi_system.h |  9 ++++++++-
 lib/sbi/sbi_system.c     | 14 ++++++++------
 2 files changed, 16 insertions(+), 7 deletions(-)

diff --git a/include/sbi/sbi_system.h b/include/sbi/sbi_system.h
index 33ff7f1a44a6..0fdcc98cce5d 100644
--- a/include/sbi/sbi_system.h
+++ b/include/sbi/sbi_system.h
@@ -48,7 +48,14 @@ struct sbi_system_suspend_device {
 	/** Name of the system suspend device */
 	char name[32];
 
-	/* Check whether sleep type is supported by the device */
+	/**
+	 * Check whether sleep type is supported by the device
+	 *
+	 * Returns 0 when @sleep_type supported, SBI_ERR_INVALID_PARAM
+	 * when @sleep_type is reserved, or SBI_ERR_NOT_SUPPORTED when
+	 * @sleep_type is not reserved and is implemented, but the
+	 * platform doesn't support it due to missing dependencies.
+	 */
 	int (*system_suspend_check)(u32 sleep_type);
 
 	/**
diff --git a/lib/sbi/sbi_system.c b/lib/sbi/sbi_system.c
index 6933915a12ed..d803ffa84189 100644
--- a/lib/sbi/sbi_system.c
+++ b/lib/sbi/sbi_system.c
@@ -111,7 +111,7 @@ void sbi_system_suspend_set_device(struct sbi_system_suspend_device *dev)
 
 static int sbi_system_suspend_test_check(u32 sleep_type)
 {
-	return sleep_type == SBI_SUSP_SLEEP_TYPE_SUSPEND;
+	return sleep_type == SBI_SUSP_SLEEP_TYPE_SUSPEND ? 0 : SBI_EINVAL;
 }
 
 static int sbi_system_suspend_test_suspend(u32 sleep_type,
@@ -142,27 +142,29 @@ void sbi_system_suspend_test_enable(void)
 bool sbi_system_suspend_supported(u32 sleep_type)
 {
 	return suspend_dev && suspend_dev->system_suspend_check &&
-	       suspend_dev->system_suspend_check(sleep_type);
+	       suspend_dev->system_suspend_check(sleep_type) == 0;
 }
 
 int sbi_system_suspend(u32 sleep_type, ulong resume_addr, ulong opaque)
 {
-	int ret = SBI_ENOTSUPP;
 	const struct sbi_domain *dom = sbi_domain_thishart_ptr();
 	struct sbi_scratch *scratch = sbi_scratch_thishart_ptr();
 	void (*jump_warmboot)(void) = (void (*)(void))scratch->warmboot_addr;
 	unsigned int hartid = current_hartid();
 	unsigned long prev_mode;
 	unsigned long i;
+	int ret;
 
 	if (!dom || !dom->system_suspend_allowed)
 		return SBI_EFAIL;
 
-	if (!suspend_dev || !suspend_dev->system_suspend)
+	if (!suspend_dev || !suspend_dev->system_suspend ||
+	    !suspend_dev->system_suspend_check)
 		return SBI_EFAIL;
 
-	if (!sbi_system_suspend_supported(sleep_type))
-		return SBI_ENOTSUPP;
+	ret = suspend_dev->system_suspend_check(sleep_type);
+	if (ret != SBI_OK)
+		return ret;
 
 	prev_mode = (csr_read(CSR_MSTATUS) & MSTATUS_MPP) >> MSTATUS_MPP_SHIFT;
 	if (prev_mode != PRV_S && prev_mode != PRV_U)
-- 
2.40.1