clk: qcom: Allow constant ratio freq tables for rcg

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>

diff --git a/drivers/clk/qcom/clk-rcg2.c b/drivers/clk/qcom/clk-rcg2.c
index 99c4bfa5365f20c38b622b66aee6e85558e50e49..8f4b9bec29565b0ca93f8f0e1c6ce60c5338b3eb 100644 (file)
--- 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 caba81d18c7003a74fc66276ac1603efedce604d..60d2a78d1395071fa344895d7e037f792f1e805b 100644 (file)
--- 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;