net: ipa: have ipa_clock_get() return a value

We currently assume no errors occur when enabling or disabling the
IPA core clock and interconnects.  And although this commit exposes
errors that could occur, we generally assume this won't happen in
practice.

This commit changes ipa_clock_get() and ipa_clock_put() so each
returns a value.  The values returned are meant to mimic what the
runtime power management functions return, so we can set up error
handling here before we make the switch.  Have ipa_clock_get()
increment the reference count even if it returns an error, to match
the behavior of pm_runtime_get().

More details follow.

When taking a reference in ipa_clock_get(), return 0 for the first
reference, 1 for subsequent references, or a negative error code if
an error occurs.  Note that if ipa_clock_get() returns an error, we
must not touch hardware; in some cases such errors now cause entire
blocks of code to be skipped.

When dropping a reference in ipa_clock_put(), we return 0 or an
error code.  The error would come from ipa_clock_disable(), which
now returns what ipa_interconnect_disable() returns (either 0 or a
negative error code).  For now, callers ignore the return value;
if an error occurs, a message will have already been logged, and
little more can actually be done to improve the situation.

Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 8 insertions, 4 deletions

diff --git a/drivers/net/ipa/ipa_uc.c b/drivers/net/ipa/ipa_uc.c
index f88ee02457d4..9c8818c39073 100644
--- a/drivers/net/ipa/ipa_uc.c
+++ b/drivers/net/ipa/ipa_uc.c
@@ -154,7 +154,7 @@ static void ipa_uc_response_hdlr(struct ipa *ipa, enum ipa_irq_id irq_id)
 	case IPA_UC_RESPONSE_INIT_COMPLETED:
 		if (ipa->uc_clocked) {
 			ipa->uc_loaded = true;
-			ipa_clock_put(ipa);
+			(void)ipa_clock_put(ipa);
 			ipa->uc_clocked = false;
 		} else {
 			dev_warn(dev, "unexpected init_completed response\n");
@@ -182,21 +182,25 @@ void ipa_uc_deconfig(struct ipa *ipa)
 	ipa_interrupt_remove(ipa->interrupt, IPA_IRQ_UC_1);
 	ipa_interrupt_remove(ipa->interrupt, IPA_IRQ_UC_0);
 	if (ipa->uc_clocked)
-		ipa_clock_put(ipa);
+		(void)ipa_clock_put(ipa);
 }
 
 /* Take a proxy clock reference for the microcontroller */
 void ipa_uc_clock(struct ipa *ipa)
 {
 	static bool already;
+	int ret;
 
 	if (already)
 		return;
 	already = true;		/* Only do this on first boot */
 
 	/* This clock reference dropped in ipa_uc_response_hdlr() above */
-	ipa_clock_get(ipa);
-	ipa->uc_clocked = true;
+	ret = ipa_clock_get(ipa);
+	if (WARN(ret < 0, "error %d getting proxy clock\n", ret))
+		(void)ipa_clock_put(ipa);
+
+	ipa->uc_clocked = ret >= 0;
 }
 
 /* Send a command to the microcontroller */