[PATCH 2/3] clk: conf: Support assigned-clock-sscs

Peng Fan (OSS)
2025-01-24T13:19:16Z

From: Peng Fan <peng.fan@nxp.com>

Parse the Spread Spectrum Configuration(SSC) from device tree and configure
them before using the clock.

Each SSC is three u32 elements which means '<modfreq spreadpercent
modmethod>', so assigned-clock-sscs is an array of multiple three u32
elements.

Signed-off-by: Peng Fan <peng.fan@nxp.com>
---
drivers/clk/clk-conf.c | 68 ++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 68 insertions(+)

diff --git a/drivers/clk/clk-conf.c b/drivers/clk/clk-conf.c
index 303a0bb26e54a95655ce094a35b989c97ebc6fd8..1ca4222caa829223d65dd37c7a776d43dc421944 100644
--- a/drivers/clk/clk-conf.c
+++ b/drivers/clk/clk-conf.c
@@ -155,6 +155,70 @@ static int __set_clk_rates(struct device_node *node, bool clk_supplier)
return 0;
}

+static int __set_clk_spread_spectrum(struct device_node *node, bool clk_supplier)
+{
+ u32 *sscs __free(kfree) = NULL;
+ u32 elem_size = sizeof(u32) * 3;
+ struct of_phandle_args clkspec;
+ int rc, count, index;
+ struct clk *clk;
+
+ /* modfreq, spreadPercent, modmethod */
+ count = of_property_count_elems_of_size(node, "assigned-clock-sscs", elem_size);
+ if (count > 0) {
+ sscs = kcalloc(count, elem_size, GFP_KERNEL);
+ if (!sscs)
+ return -ENOMEM;
+ rc = of_property_read_u32_array(node,
+ "assigned-clock-sscs",
+ sscs, count * 3);
+ } else {
+ return 0;
+ }
+
+ if (rc)
+ return rc;
+
+ for (index = 0; index < count; index++) {
+ u32 modfreq = sscs[index * 3], spreadpercent = sscs[index * 3 + 1];
+ u32 method = sscs[index * 3 + 2];
+
+ if (modfreq || spreadpercent || method) {
+ rc = of_parse_phandle_with_args(node, "assigned-clocks",
+ "#clock-cells", index, &clkspec);
+ if (rc < 0) {
+ /* skip empty (null) phandles */
+ if (rc == -ENOENT)
+ continue;
+ else
+ return rc;
+ }
+
+ if (clkspec.np == node && !clk_supplier) {
+ of_node_put(clkspec.np);
+ return 0;
+ }
+
+ clk = of_clk_get_from_provider(&clkspec);
+ of_node_put(clkspec.np);
+ if (IS_ERR(clk)) {
+ if (PTR_ERR(clk) != -EPROBE_DEFER)
+ pr_warn("clk: couldn't get clock %d for %pOF\n",
+ index, node);
+ return PTR_ERR(clk);
+ }
+
+ rc = clk_set_spread_spectrum(clk, modfreq, spreadpercent, method, true);
+ if (rc < 0)
+ pr_err("clk: couldn't set %s clk spread spectrum %u %u %u: %d\n",
+ __clk_get_name(clk), modfreq, spreadpercent, method, rc);
+ clk_put(clk);
+ }
+ }
+
+ return 0;
+}
+
/**
* of_clk_set_defaults() - parse and set assigned clocks configuration
* @node: device node to apply clock settings for
@@ -174,6 +238,10 @@ int of_clk_set_defaults(struct device_node *node, bool clk_supplier)
if (!node)
return 0;

+ rc = __set_clk_spread_spectrum(node, clk_supplier);
+ if (rc < 0)
+ return rc;
+
rc = __set_clk_parents(node, clk_supplier);
if (rc < 0)
return rc;

--
2.35.3