SCMI v2.0 adds support for "FastChannel" which do not use a message
header as they are specialized for a single message.

Only PERFORMANCE_LIMITS_{SET,GET} and PERFORMANCE_LEVEL_{SET,GET}
commands are supported over fastchannels. As they are optional, they
need to be discovered by PERFORMANCE_DESCRIBE_FASTCHANNEL command.
Further {LIMIT,LEVEL}_SET commands can have optional doorbell support.

Add support for making use of these fastchannels.

Cc: Ionela Voinescu <ionela.voine...@arm.com>
Cc: Chris Redpath <chris.redp...@arm.com>
Cc: Quentin Perret <quentin.per...@arm.com>
Signed-off-by: Sudeep Holla <sudeep.ho...@arm.com>
---
 drivers/firmware/arm_scmi/perf.c | 104 +++++++++++++++++++++++++++++--
 1 file changed, 100 insertions(+), 4 deletions(-)

diff --git a/drivers/firmware/arm_scmi/perf.c b/drivers/firmware/arm_scmi/perf.c
index 6cce3e82e81e..b9144efbd6fb 100644
--- a/drivers/firmware/arm_scmi/perf.c
+++ b/drivers/firmware/arm_scmi/perf.c
@@ -8,6 +8,7 @@
 #include <linux/bits.h>
 #include <linux/of.h>
 #include <linux/io.h>
+#include <linux/io-64-nonatomic-hi-lo.h>
 #include <linux/platform_device.h>
 #include <linux/pm_opp.h>
 #include <linux/sort.h>
@@ -293,7 +294,42 @@ scmi_perf_describe_levels_get(const struct scmi_handle 
*handle, u32 domain,
        return ret;
 }
 
-static int scmi_perf_limits_set(const struct scmi_handle *handle, u32 domain,
+#define SCMI_PERF_FC_RING_DB(doorbell, w)              \
+{                                                      \
+       u##w val = 0;                                   \
+       struct scmi_fc_db_info *db = doorbell;          \
+                                                       \
+       if ((db)->mask)                                 \
+               val = ioread##w(db->addr) & db->mask;   \
+       iowrite##w((u##w)db->set | val, db->addr);      \
+}
+
+static void scmi_perf_fc_ring_db(struct scmi_fc_db_info *db)
+{
+       if (!db || !db->addr)
+               return;
+
+       if (db->width == 1)
+               SCMI_PERF_FC_RING_DB(db, 8)
+       else if (db->width == 2)
+               SCMI_PERF_FC_RING_DB(db, 16)
+       else if (db->width == 4)
+               SCMI_PERF_FC_RING_DB(db, 32)
+       else /* db->width == 8 */
+#ifdef CONFIG_64BIT
+               SCMI_PERF_FC_RING_DB(db, 64)
+#else
+       {
+               u64 val = 0;
+
+               if (db->mask)
+                       val = ioread64_hi_lo(db->addr) & db->mask;
+               iowrite64_hi_lo(db->set, db->addr);
+       }
+#endif
+}
+
+static int scmi_perf_mb_limits_set(const struct scmi_handle *handle, u32 
domain,
                                   u32 max_perf, u32 min_perf)
 {
        int ret;
@@ -316,7 +352,23 @@ static int scmi_perf_limits_set(const struct scmi_handle 
*handle, u32 domain,
        return ret;
 }
 
-static int scmi_perf_limits_get(const struct scmi_handle *handle, u32 domain,
+static int scmi_perf_limits_set(const struct scmi_handle *handle, u32 domain,
+                               u32 max_perf, u32 min_perf)
+{
+       struct scmi_perf_info *pi = handle->perf_priv;
+       struct perf_dom_info *dom = pi->dom_info + domain;
+
+       if (dom->fc_info && dom->fc_info->limit_set_addr) {
+               iowrite32(max_perf, dom->fc_info->limit_set_addr);
+               iowrite32(min_perf, dom->fc_info->limit_set_addr + 4);
+               scmi_perf_fc_ring_db(dom->fc_info->limit_set_db);
+               return 0;
+       }
+
+       return scmi_perf_mb_limits_set(handle, domain, max_perf, min_perf);
+}
+
+static int scmi_perf_mb_limits_get(const struct scmi_handle *handle, u32 
domain,
                                   u32 *max_perf, u32 *min_perf)
 {
        int ret;
@@ -342,7 +394,22 @@ static int scmi_perf_limits_get(const struct scmi_handle 
*handle, u32 domain,
        return ret;
 }
 
-static int scmi_perf_level_set(const struct scmi_handle *handle, u32 domain,
+static int scmi_perf_limits_get(const struct scmi_handle *handle, u32 domain,
+                               u32 *max_perf, u32 *min_perf)
+{
+       struct scmi_perf_info *pi = handle->perf_priv;
+       struct perf_dom_info *dom = pi->dom_info + domain;
+
+       if (dom->fc_info && dom->fc_info->limit_get_addr) {
+               *max_perf = ioread32(dom->fc_info->limit_get_addr);
+               *min_perf = ioread32(dom->fc_info->limit_get_addr + 4);
+               return 0;
+       }
+
+       return scmi_perf_mb_limits_get(handle, domain, max_perf, min_perf);
+}
+
+static int scmi_perf_mb_level_set(const struct scmi_handle *handle, u32 domain,
                                  u32 level, bool poll)
 {
        int ret;
@@ -365,7 +432,22 @@ static int scmi_perf_level_set(const struct scmi_handle 
*handle, u32 domain,
        return ret;
 }
 
-static int scmi_perf_level_get(const struct scmi_handle *handle, u32 domain,
+static int scmi_perf_level_set(const struct scmi_handle *handle, u32 domain,
+                              u32 level, bool poll)
+{
+       struct scmi_perf_info *pi = handle->perf_priv;
+       struct perf_dom_info *dom = pi->dom_info + domain;
+
+       if (dom->fc_info && dom->fc_info->level_set_addr) {
+               iowrite32(level, dom->fc_info->level_set_addr);
+               scmi_perf_fc_ring_db(dom->fc_info->level_set_db);
+               return 0;
+       }
+
+       return scmi_perf_mb_level_set(handle, domain, level, poll);
+}
+
+static int scmi_perf_mb_level_get(const struct scmi_handle *handle, u32 domain,
                                  u32 *level, bool poll)
 {
        int ret;
@@ -387,6 +469,20 @@ static int scmi_perf_level_get(const struct scmi_handle 
*handle, u32 domain,
        return ret;
 }
 
+static int scmi_perf_level_get(const struct scmi_handle *handle, u32 domain,
+                              u32 *level, bool poll)
+{
+       struct scmi_perf_info *pi = handle->perf_priv;
+       struct perf_dom_info *dom = pi->dom_info + domain;
+
+       if (dom->fc_info && dom->fc_info->level_get_addr) {
+               *level = ioread32(dom->fc_info->level_get_addr);
+               return 0;
+       }
+
+       return scmi_perf_mb_level_get(handle, domain, level, poll);
+}
+
 static bool scmi_perf_fc_size_is_valid(u32 msg, u32 size)
 {
        if ((msg == PERF_LEVEL_GET || msg == PERF_LEVEL_SET) && size == 4)
-- 
2.17.1

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