From 7faa13a9f90a7f73b3f8fd501f71e07ddca84192 Mon Sep 17 00:00:00 2001
From: Jeffrey Hugo <jeffrey.l.hugo@gmail.com>
Date: Thu, 31 Oct 2019 11:57:15 -0700
Subject: [PATCH] clk: qcom: Allow constant ratio freq tables for rcg

commit efd164b5520afd6fb2883b68e0d408a7de29c491 upstream.

Some RCGs (the gfx_3d_src_clk in msm8998 for example) are basically just
some constant ratio from the input across the entire frequency range.  It
would be great if we could specify the frequency table as a single entry
constant ratio instead of a long list, ie:

	{ .src = P_GPUPLL0_OUT_EVEN, .pre_div = 3 },
        { }

So, lets support that.

We need to fix a corner case in qcom_find_freq() where if the freq table
is non-null, but has no frequencies, we end up returning an "entry" before
the table array, which is bad.  Then, we need ignore the freq from the
table, and instead base everything on the requested freq.

Suggested-by: Stephen Boyd <sboyd@kernel.org>
Signed-off-by: Jeffrey Hugo <jeffrey.l.hugo@gmail.com>
Link: https://lkml.kernel.org/r/20191031185715.15504-1-jeffrey.l.hugo@gmail.com
Signed-off-by: Stephen Boyd <sboyd@kernel.org>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

diff --git a/drivers/clk/qcom/clk-rcg2.c b/drivers/clk/qcom/clk-rcg2.c
index 8c02bffe50df..106509a27515 100644
--- a/drivers/clk/qcom/clk-rcg2.c
+++ b/drivers/clk/qcom/clk-rcg2.c
@@ -220,6 +220,8 @@ static int _freq_tbl_determine_rate(struct clk_hw *hw, const struct freq_tbl *f,
 	if (clk_flags & CLK_SET_RATE_PARENT) {
 		rate = f->freq;
 		if (f->pre_div) {
+			if (!rate)
+				rate = req->rate;
 			rate /= 2;
 			rate *= f->pre_div + 1;
 		}
diff --git a/drivers/clk/qcom/common.c b/drivers/clk/qcom/common.c
index a6b2f86112d8..caac03fc4fab 100644
--- a/drivers/clk/qcom/common.c
+++ b/drivers/clk/qcom/common.c
@@ -29,6 +29,9 @@ struct freq_tbl *qcom_find_freq(const struct freq_tbl *f, unsigned long rate)
 	if (!f)
 		return NULL;
 
+	if (!f->freq)
+		return f;
+
 	for (; f->freq; f++)
 		if (rate <= f->freq)
 			return f;
-- 
2.7.4