[PATCH NOT APPLY v2 4/4] clk: scmi: Support spread spectrum

Peng Fan (OSS)
2025-02-05T09:51:13Z

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

Support Spread Spectrum with adding scmi_clk_set_spread_spectrum

Signed-off-by: Peng Fan <peng.fan@nxp.com>
---
drivers/clk/clk-scmi.c | 47 +++++++++++++++++++++++++++++++++++++++++--
include/linux/scmi_protocol.h | 6 ++++++
2 files changed, 51 insertions(+), 2 deletions(-)

diff --git a/drivers/clk/clk-scmi.c b/drivers/clk/clk-scmi.c
index 15510c2ff21c0335f5cb30677343bd4ef59c0738..56b9d0166b0170807c1a83fff391033fecee2159 100644
--- a/drivers/clk/clk-scmi.c
+++ b/drivers/clk/clk-scmi.c
@@ -23,6 +23,7 @@ enum scmi_clk_feats {
SCMI_CLK_RATE_CTRL_SUPPORTED,
SCMI_CLK_PARENT_CTRL_SUPPORTED,
SCMI_CLK_DUTY_CYCLE_SUPPORTED,
+ SCMI_CLK_SSC_SUPPORTED,
SCMI_CLK_FEATS_COUNT
};

@@ -98,6 +99,36 @@ static int scmi_clk_set_parent(struct clk_hw *hw, u8 parent_index)
return scmi_proto_clk_ops->parent_set(clk->ph, clk->id, parent_index);
}

+static int scmi_clk_set_spread_spectrum(struct clk_hw *hw,
+ struct clk_spread_spectrum *clk_ss)
+{
+ struct scmi_clk *clk = to_scmi_clk(hw);
+ int ret;
+ u32 val;
+
+ /*
+ * extConfigValue[7:0] - spread percentage (%)
+ * extConfigValue[23:8] - Modulation Frequency (KHz)
+ * extConfigValue[24] - Enable/Disable
+ * extConfigValue[31:25] - Modulation method
+ */
+ val = FIELD_PREP(SCMI_CLOCK_EXT_SS_PERCENTAGE_MASK, clk_ss->spreaddepth);
+ val |= FIELD_PREP(SCMI_CLOCK_EXT_SS_MOD_FREQ_MASK, clk_ss->modfreq);
+ val |= FIELD_PREP(SCMI_CLOCK_EXT_SS_METHOD_MASK, clk_ss->method);
+ if (clk_ss->enable)
+ val |= SCMI_CLOCK_EXT_SS_ENABLE_MASK;
+ ret = scmi_proto_clk_ops->config_oem_set(clk->ph, clk->id,
+ SCMI_CLOCK_CFG_SSC,
+ val, false);
+ if (ret)
+ dev_warn(clk->dev,
+ "Failed to set spread spectrum(%u,%u,%u) for clock ID %d\n",
+ clk_ss->modfreq, clk_ss->spreaddepth, clk_ss->method,
+ clk->id);
+
+ return ret;
+}
+
static u8 scmi_clk_get_parent(struct clk_hw *hw)
{
struct scmi_clk *clk = to_scmi_clk(hw);
@@ -316,9 +347,17 @@ scmi_clk_ops_alloc(struct device *dev, unsigned long feats_key)
ops->set_duty_cycle = scmi_clk_set_duty_cycle;
}

+ if (feats_key & BIT(SCMI_CLK_SSC_SUPPORTED))
+ ops->set_spread_spectrum = scmi_clk_set_spread_spectrum;
+
return ops;
}

+static const char * const scmi_clk_imxlist[] = {
+ "fsl,imx95",
+ NULL
+};
+
/**
* scmi_clk_ops_select() - Select a proper set of clock operations
* @sclk: A reference to an SCMI clock descriptor
@@ -370,8 +409,12 @@ scmi_clk_ops_select(struct scmi_clk *sclk, bool atomic_capable,
if (!ci->parent_ctrl_forbidden)
feats_key |= BIT(SCMI_CLK_PARENT_CTRL_SUPPORTED);

- if (ci->extended_config)
- feats_key |= BIT(SCMI_CLK_DUTY_CYCLE_SUPPORTED);
+ if (ci->extended_config) {
+ if (of_machine_compatible_match(scmi_clk_imxlist))
+ feats_key |= BIT(SCMI_CLK_SSC_SUPPORTED);
+ else
+ feats_key |= BIT(SCMI_CLK_DUTY_CYCLE_SUPPORTED);
+ }

if (WARN_ON(feats_key >= db_size))
return NULL;
diff --git a/include/linux/scmi_protocol.h b/include/linux/scmi_protocol.h
index 688466a0e816247d24704f7ba109667a14226b67..a02a6d55568898ad0b5deed954e432415936dde2 100644
--- a/include/linux/scmi_protocol.h
+++ b/include/linux/scmi_protocol.h
@@ -79,10 +79,16 @@ struct scmi_protocol_handle;
enum scmi_clock_oem_config {
SCMI_CLOCK_CFG_DUTY_CYCLE = 0x1,
SCMI_CLOCK_CFG_PHASE,
+ SCMI_CLOCK_CFG_SSC,
SCMI_CLOCK_CFG_OEM_START = 0x80,
SCMI_CLOCK_CFG_OEM_END = 0xFF,
};

+#define SCMI_CLOCK_EXT_SS_PERCENTAGE_MASK GENMASK(7, 0)
+#define SCMI_CLOCK_EXT_SS_MOD_FREQ_MASK GENMASK(23, 8)
+#define SCMI_CLOCK_EXT_SS_ENABLE_MASK BIT(24)
+#define SCMI_CLOCK_EXT_SS_METHOD_MASK GENMASK(31, 25)
+
/**
* struct scmi_clk_proto_ops - represents the various operations provided
* by SCMI Clock Protocol

--
2.37.1