summaryrefslogtreecommitdiffstats
path: root/drivers/clk
diff options
context:
space:
mode:
authorPeng Fan <peng.fan@nxp.com>2020-02-19 15:59:48 +0800
committerShawn Guo <shawnguo@kernel.org>2020-03-10 14:02:02 +0800
commitc88a4c797a50574c90ca11f72ab10dbded7d768e (patch)
tree1147b84efb58e8fe21b516d6f6ff1ab717e3e6ad /drivers/clk
parent8ffe9c7bb9e47745b8a678629b22f57b23b8dac5 (diff)
downloadlinux-c88a4c797a50574c90ca11f72ab10dbded7d768e.tar.gz
linux-c88a4c797a50574c90ca11f72ab10dbded7d768e.tar.bz2
linux-c88a4c797a50574c90ca11f72ab10dbded7d768e.zip
clk: imx: pfdv2: determine best parent rate
pfdv2 is only used in i.MX7ULP. To get best pfd output, the i.MX7ULP Datasheet defines two best PLL rate and pfd frac. Per Datasheel All PLLs on i.MX 7ULP either have VCO base frequency of 480 MHz or 528 MHz. So when determine best rate, we also determine best parent rate which could match the requirement. For some reason the current parent might not be 480MHz or 528MHz, so we still take current parent rate as a choice. And we also enable flag CLK_SET_RATE_PARENT to let parent rate to be configured. Signed-off-by: Peng Fan <peng.fan@nxp.com> Signed-off-by: Shawn Guo <shawnguo@kernel.org>
Diffstat (limited to 'drivers/clk')
-rw-r--r--drivers/clk/imx/clk-pfdv2.c50
1 files changed, 33 insertions, 17 deletions
diff --git a/drivers/clk/imx/clk-pfdv2.c b/drivers/clk/imx/clk-pfdv2.c
index 28b5f208ced9..78e1f7641aaa 100644
--- a/drivers/clk/imx/clk-pfdv2.c
+++ b/drivers/clk/imx/clk-pfdv2.c
@@ -101,24 +101,40 @@ static unsigned long clk_pfdv2_recalc_rate(struct clk_hw *hw,
static int clk_pfdv2_determine_rate(struct clk_hw *hw,
struct clk_rate_request *req)
{
- u64 tmp = req->best_parent_rate;
- u64 rate = req->rate;
+ unsigned long parent_rates[] = {
+ 480000000,
+ 528000000,
+ req->best_parent_rate
+ };
+ unsigned long best_rate = -1UL, rate = req->rate;
+ unsigned long best_parent_rate = req->best_parent_rate;
+ u64 tmp;
u8 frac;
+ int i;
+
+ for (i = 0; i < ARRAY_SIZE(parent_rates); i++) {
+ tmp = parent_rates[i];
+ tmp = tmp * 18 + rate / 2;
+ do_div(tmp, rate);
+ frac = tmp;
+
+ if (frac < 12)
+ frac = 12;
+ else if (frac > 35)
+ frac = 35;
+
+ tmp = parent_rates[i];
+ tmp *= 18;
+ do_div(tmp, frac);
+
+ if (abs(tmp - req->rate) < abs(best_rate - req->rate)) {
+ best_rate = tmp;
+ best_parent_rate = parent_rates[i];
+ }
+ }
- tmp = tmp * 18 + rate / 2;
- do_div(tmp, rate);
- frac = tmp;
-
- if (frac < 12)
- frac = 12;
- else if (frac > 35)
- frac = 35;
-
- tmp = req->best_parent_rate;
- tmp *= 18;
- do_div(tmp, frac);
-
- req->rate = tmp;
+ req->best_parent_rate = best_parent_rate;
+ req->rate = best_rate;
return 0;
}
@@ -198,7 +214,7 @@ struct clk_hw *imx_clk_hw_pfdv2(const char *name, const char *parent_name,
init.ops = &clk_pfdv2_ops;
init.parent_names = &parent_name;
init.num_parents = 1;
- init.flags = CLK_SET_RATE_GATE;
+ init.flags = CLK_SET_RATE_GATE | CLK_SET_RATE_PARENT;
pfd->hw.init = &init;