[PATCH 2/3] clk: conf: Support assigned-clock-sscs
From: Peng Fan <peng.fan@nxp.com>
Date: 2025-08-12 12:18:44
Also in:
arm-scmi, linux-clk, lkml
Subsystem:
common clk framework, the rest · Maintainers:
Michael Turquette, Stephen Boyd, Linus Torvalds
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 spreaddepth 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 | 70 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 70 insertions(+)
diff --git a/drivers/clk/clk-conf.c b/drivers/clk/clk-conf.c
index 303a0bb26e54a95655ce094a35b989c97ebc6fd8..81a2c1f8ca4c44df2c54c1e51f800f533c9453b3 100644
--- a/drivers/clk/clk-conf.c
+++ b/drivers/clk/clk-conf.c@@ -155,6 +155,72 @@ 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_hz = sscs[index * 3], spread_bp = sscs[index * 3 + 1]; + u32 method = sscs[index * 3 + 2]; + struct clk_hw *hw; + + if (modfreq_hz || spread_bp || 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); + } + + hw = __clk_get_hw(clk); + rc = clk_hw_set_spread_spectrum(hw, modfreq_hz, spread_bp, method); + if (rc < 0) + pr_err("clk: couldn't set %s clk spread spectrum %u %u %u: %d\n", + __clk_get_name(clk), modfreq_hz, spread_bp, 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 +240,10 @@ 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;
--
2.37.1