linux-kernel - [PATCH 2/4] spi: qup: Parse OPP table for DVFS support

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Message-Id: <20230912-spi-qup-dvfs-v1-2-3e38aa09c2bd@kernkonzept.com>
Date:   Tue, 12 Sep 2023 16:30:37 +0200
From:   Stephan Gerhold <stephan.gerhold@...nkonzept.com>
To:     Mark Brown <broonie@...nel.org>
Cc:     Andy Gross <agross@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio <konrad.dybcio@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
        linux-arm-msm@...r.kernel.org, linux-spi@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        Stephan Gerhold <stephan.gerhold@...nkonzept.com>
Subject: [PATCH 2/4] spi: qup: Parse OPP table for DVFS support

Parse the OPP table from the device tree and use dev_pm_opp_set_rate()
instead of clk_set_rate() to allow making performance state for power
domains specified in the OPP table.

This is needed to guarantee correct behavior of the clock, especially
with the higher clock/SPI bus frequencies.

Signed-off-by: Stephan Gerhold <stephan.gerhold@...nkonzept.com>
---
 drivers/spi/spi-qup.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/drivers/spi/spi-qup.c b/drivers/spi/spi-qup.c
index 4b6f6b25219b..bf043be3a2a9 100644
--- a/drivers/spi/spi-qup.c
+++ b/drivers/spi/spi-qup.c
@@ -12,6 +12,7 @@
 #include <linux/module.h>
 #include <linux/of.h>
 #include <linux/platform_device.h>
+#include <linux/pm_opp.h>
 #include <linux/pm_runtime.h>
 #include <linux/spi/spi.h>
 #include <linux/dmaengine.h>
@@ -667,7 +668,7 @@ static int spi_qup_io_prep(struct spi_device *spi, struct spi_transfer *xfer)
 		return -EIO;
 	}
 
-	ret = clk_set_rate(controller->cclk, xfer->speed_hz);
+	ret = dev_pm_opp_set_rate(controller->dev, xfer->speed_hz);
 	if (ret) {
 		dev_err(controller->dev, "fail to set frequency %d",
 			xfer->speed_hz);
@@ -1027,6 +1028,15 @@ static int spi_qup_probe(struct platform_device *pdev)
 		return -ENXIO;
 	}
 
+	ret = devm_pm_opp_set_clkname(dev, "core");
+	if (ret)
+		return ret;
+
+	/* OPP table is optional */
+	ret = devm_pm_opp_of_add_table(dev);
+	if (ret && ret != -ENODEV)
+		return dev_err_probe(dev, ret, "invalid OPP table\n");
+
 	host = spi_alloc_host(dev, sizeof(struct spi_qup));
 	if (!host) {
 		dev_err(dev, "cannot allocate host\n");

-- 
2.39.2