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

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Message-Id: <20250205-clk-ssc-v2-4-fa73083caa92@nxp.com>
Date: Wed, 05 Feb 2025 17:49:54 +0800
From: "Peng Fan (OSS)" <peng.fan@....nxp.com>
To: Michael Turquette <mturquette@...libre.com>, 
 Stephen Boyd <sboyd@...nel.org>, Russell King <linux@...linux.org.uk>, 
 Sudeep Holla <sudeep.holla@....com>, 
 Cristian Marussi <cristian.marussi@....com>, 
 Abel Vesa <abelvesa@...nel.org>
Cc: linux-clk@...r.kernel.org, linux-kernel@...r.kernel.org, 
 arm-scmi@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, 
 Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk@...nel.org>, 
 Dario Binacchi <dario.binacchi@...rulasolutions.com>, 
 Shawn Guo <shawnguo@...nel.org>, Sascha Hauer <s.hauer@...gutronix.de>, 
 Pengutronix Kernel Team <kernel@...gutronix.de>, 
 Fabio Estevam <festevam@...il.com>, imx@...ts.linux.dev, 
 Peng Fan <peng.fan@....com>
Subject: [PATCH NOT APPLY v2 4/4] clk: scmi: Support spread spectrum

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

Support Spread Spectrum with adding scmi_clk_set_spread_spectrum

Signed-off-by: Peng Fan <peng.fan@....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