bus: mhi: Fix pm_state conversion to string

commit 64f93a9 upstream.

On big endian architectures the mhi debugfs files which report pm state
give "Invalid State" for all states.  This is caused by using
find_last_bit which takes an unsigned long* while the state is passed in
as an enum mhi_pm_state which will be of int size.

Fix by using __fls to pass the value of state instead of find_last_bit.

Also the current API expects "mhi_pm_state" enumerator as the function
argument but the function only works with bitmasks. So as Alex suggested,
let's change the argument to u32 to avoid confusion.

Fixes: a6e2e35 ("bus: mhi: core: Add support for PM state transitions")
Cc: stable@vger.kernel.org
[mani: changed the function argument to u32]
Reviewed-by: Manivannan Sadhasivam <mani@kernel.org>
Reviewed-by: Hemant Kumar <hemantk@codeaurora.org>
Reviewed-by: Alex Elder <elder@linaro.org>
Signed-off-by: Paul Davey <paul.davey@alliedtelesis.co.nz>
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/r/20220301160308.107452-3-manivannan.sadhasivam@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/bus/mhi/core/init.c

@@ -77,12 +77,14 @@ static const char * const mhi_pm_state_str[] = {
 	[MHI_PM_STATE_LD_ERR_FATAL_DETECT] = "Linkdown or Error Fatal Detect",
 };
 
-const char *to_mhi_pm_state_str(enum mhi_pm_state state)
+const char *to_mhi_pm_state_str(u32 state)
 {
-	unsigned long pm_state = state;
-	int index = find_last_bit(&pm_state, 32);
+	int index;
 
-	if (index >= ARRAY_SIZE(mhi_pm_state_str))
+	if (state)
+		index = __fls(state);
+
+	if (!state || index >= ARRAY_SIZE(mhi_pm_state_str))
 		return "Invalid State";
 
 	return mhi_pm_state_str[index];

drivers/bus/mhi/core/internal.h

@@ -622,7 +622,7 @@ void mhi_free_bhie_table(struct mhi_controller *mhi_cntrl,
 enum mhi_pm_state __must_check mhi_tryset_pm_state(
 					struct mhi_controller *mhi_cntrl,
 					enum mhi_pm_state state);
-const char *to_mhi_pm_state_str(enum mhi_pm_state state);
+const char *to_mhi_pm_state_str(u32 state);
 int mhi_queue_state_transition(struct mhi_controller *mhi_cntrl,
 			       enum dev_st_transition state);
 void mhi_pm_st_worker(struct work_struct *work);