Some NKM PLLs, frequency can be set above PLL working range.

Add a constraint for maximum supported rate. This way, drivers can
specify which is maximum allowed rate for PLL.

Signed-off-by: Jagan Teki <ja...@amarulasolutions.com>
Acked-by: Stephen Boyd <sb...@kernel.org>
Tested-by: Jagan Teki <ja...@amarulasolutions.com>
---
Changes for v3:
- collect Stephen Ack
- add tested credit
Changes for v2:
- none

 drivers/clk/sunxi-ng/ccu_nkm.c | 7 +++++++
 drivers/clk/sunxi-ng/ccu_nkm.h | 1 +
 2 files changed, 8 insertions(+)

diff --git a/drivers/clk/sunxi-ng/ccu_nkm.c b/drivers/clk/sunxi-ng/ccu_nkm.c
index d17539dc88dd..574fd2cd2a79 100644
--- a/drivers/clk/sunxi-ng/ccu_nkm.c
+++ b/drivers/clk/sunxi-ng/ccu_nkm.c
@@ -132,6 +132,13 @@ static unsigned long ccu_nkm_round_rate(struct 
ccu_mux_internal *mux,
                return rate;
        }
 
+       if (nkm->max_rate && rate > nkm->max_rate) {
+               rate = nkm->max_rate;
+               if (nkm->common.features & CCU_FEATURE_FIXED_POSTDIV)
+                       rate /= nkm->fixed_post_div;
+               return rate;
+       }
+
        ccu_nkm_find_best(*parent_rate, rate, &_nkm);
 
        rate = *parent_rate * _nkm.n * _nkm.k / _nkm.m;
diff --git a/drivers/clk/sunxi-ng/ccu_nkm.h b/drivers/clk/sunxi-ng/ccu_nkm.h
index ff5bd00f429f..c82590481188 100644
--- a/drivers/clk/sunxi-ng/ccu_nkm.h
+++ b/drivers/clk/sunxi-ng/ccu_nkm.h
@@ -36,6 +36,7 @@ struct ccu_nkm {
 
        unsigned int            fixed_post_div;
        unsigned int            min_rate;
+       unsigned int            max_rate;
 
        struct ccu_common       common;
 };
-- 
2.18.0.321.gffc6fa0e3

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