linux-kernel - [PATCH 3/3] pwm: axi-pwmgen: add support for external clock

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Message-Id: <20250520-pwm-axi-pwmgen-add-external-clock-v1-3-6cd63cc001c8@baylibre.com>
Date: Tue, 20 May 2025 16:00:46 -0500
From: David Lechner <dlechner@...libre.com>
To: Michael Hennerich <michael.hennerich@...log.com>, 
 Nuno Sá <nuno.sa@...log.com>, 
 Trevor Gamblin <tgamblin@...libre.com>, 
 Uwe Kleine-König <ukleinek@...nel.org>, 
 Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, 
 Conor Dooley <conor+dt@...nel.org>
Cc: linux-pwm@...r.kernel.org, devicetree@...r.kernel.org, 
 linux-kernel@...r.kernel.org, David Lechner <dlechner@...libre.com>
Subject: [PATCH 3/3] pwm: axi-pwmgen: add support for external clock

Add support for external clock to the AXI PWM generator driver.

In most cases, there is a separate external clock that drives the PWM
output separate from the peripheral clock. This allows enabling both
clocks.

Signed-off-by: David Lechner <dlechner@...libre.com>
---
 drivers/pwm/pwm-axi-pwmgen.c | 23 ++++++++++++++++++++---
 1 file changed, 20 insertions(+), 3 deletions(-)

diff --git a/drivers/pwm/pwm-axi-pwmgen.c b/drivers/pwm/pwm-axi-pwmgen.c
index 4337c8f5acf055fc87dc134f2a70b99b0cb5ede6..67992a7561ec0440b1c1fa327f844a0602872771 100644
--- a/drivers/pwm/pwm-axi-pwmgen.c
+++ b/drivers/pwm/pwm-axi-pwmgen.c
@@ -280,9 +280,26 @@ static int axi_pwmgen_probe(struct platform_device *pdev)
 	ddata = pwmchip_get_drvdata(chip);
 	ddata->regmap = regmap;
 
-	clk = devm_clk_get_enabled(dev, NULL);
-	if (IS_ERR(clk))
-		return dev_err_probe(dev, PTR_ERR(clk), "failed to get clock\n");
+	/* When clock-names is present, there is a separate ext clock. */
+	if (device_property_present(dev, "clock-names")) {
+		struct clk *axi_clk;
+
+		axi_clk = devm_clk_get_enabled(dev, "axi");
+		if (IS_ERR(axi_clk))
+			return dev_err_probe(dev, PTR_ERR(axi_clk),
+					     "failed to get axi clock\n");
+
+		clk = devm_clk_get_enabled(dev, "ext");
+		if (IS_ERR(clk))
+			return dev_err_probe(dev, PTR_ERR(clk),
+					     "failed to get ext clock\n");
+	} else {
+		/* Otherwise, a single clock does everything. */
+		clk = devm_clk_get_enabled(dev, NULL);
+		if (IS_ERR(clk))
+			return dev_err_probe(dev, PTR_ERR(clk),
+					     "failed to get clock\n");
+	}
 
 	ret = devm_clk_rate_exclusive_get(dev, clk);
 	if (ret)

-- 
2.43.0