From: "Gautham R. Shenoy" <redacted>

On POWER8 and POWER9, the PMSR and the PMCR registers define pstates
to be 8-bit wide values. The device-tree exports pstates as 32-bit
wide values of which the lower byte is the actual pstate.

The current implementation in the kernel treats pstates as integer
type, since it used to use the sign of the pstate for performing some
boundary-checks. This is no longer required after the patch
"powernv-cpufreq: Fix pstate_to_idx() to handle non-continguous
pstates".

So, in this patch, we modify the powernv-cpufreq driver to uniformly
treat pstates as opaque 8-bit values obtained from the device-tree or
the PMCR. This simplifies the extract_pstate() helper function since
we no longer no longer require to worry about the sign-extentions.

Signed-off-by: Gautham R. Shenoy <redacted>
---
 drivers/cpufreq/powernv-cpufreq.c | 47 ++++++++++++++++-----------------------
 1 file changed, 19 insertions(+), 28 deletions(-)

diff --git a/drivers/cpufreq/powernv-cpufreq.c b/drivers/cpufreq/powernv-cpufreq.c
index 8e3dbca..8a4e2ce 100644
--- a/drivers/cpufreq/powernv-cpufreq.c
+++ b/drivers/cpufreq/powernv-cpufreq.c

@@ -110,12 +110,11 @@ struct global_pstate_info {
  *         hashtable
  */
 struct pstate_idx_revmap_data {
-       int pstate_id;
+       u8 pstate_id;
        unsigned int cpufreq_table_idx;
        struct hlist_node hentry;
 };

-u32 pstate_sign_prefix;
 static bool rebooting, throttled, occ_reset;

 static const char * const throttle_reason[] = {

@@ -170,14 +169,9 @@ enum throttle_reason_type {
        bool wof_enabled;
 } powernv_pstate_info;

-static inline int extract_pstate(u64 pmsr_val, unsigned int shift)
+static inline u8 extract_pstate(u64 pmsr_val, unsigned int shift)
 {
-       int ret = ((pmsr_val >> shift) & 0xFF);
-
-       if (!ret)
-               return ret;
-
-       return (pstate_sign_prefix | ret);
+       return ((pmsr_val >> shift) & 0xFF);
 }