linux-kernel - [RFC 07/19] devfreq: imx8m-ddrc: Add late system sleep PM ops

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Date:   Fri, 19 Feb 2021 18:00:04 +0200
From:   Abel Vesa <abel.vesa@....com>
To:     Rob Herring <robh@...nel.org>, Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <kernel@...gutronix.de>,
        Lucas Stach <l.stach@...gutronix.de>,
        Fabio Estevam <festevam@...il.com>,
        Chanwoo Choi <cw00.choi@...sung.com>,
        Georgi Djakov <djakov@...nel.org>,
        Dong Aisheng <aisheng.dong@....com>,
        Peng Fan <peng.fan@....com>,
        Martin Kepplinger <martink@...teo.de>,
        devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-clk@...r.kernel.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Cc:     NXP Linux Team <linux-imx@....com>, Abel Vesa <abel.vesa@....com>
Subject: [RFC 07/19] devfreq: imx8m-ddrc: Add late system sleep PM ops

Seems that, in order to be able to resume from suspend, the dram rate
needs to be the highest one available. Therefore, add the late system
suspend/resume PM ops which set the highest rate on suspend and the
latest one used before suspending on resume.

Signed-off-by: Abel Vesa <abel.vesa@....com>
---
 drivers/devfreq/imx8m-ddrc.c | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/drivers/devfreq/imx8m-ddrc.c b/drivers/devfreq/imx8m-ddrc.c
index 33de83acfd8b..04347dee781b 100644
--- a/drivers/devfreq/imx8m-ddrc.c
+++ b/drivers/devfreq/imx8m-ddrc.c
@@ -72,6 +72,8 @@ struct imx8m_ddrc {
 	struct clk *dram_alt;
 	struct clk *dram_apb;
 
+	unsigned long suspend_rate;
+	unsigned long resume_rate;
 	int freq_count;
 	struct imx8m_ddrc_freq freq_table[IMX8M_DDRC_MAX_FREQ_COUNT];
 };
@@ -271,6 +273,22 @@ static int imx8m_ddrc_target(struct device *dev, unsigned long *freq, u32 flags)
 	return ret;
 }
 
+static int imx8m_ddrc_suspend(struct device *dev)
+{
+	struct imx8m_ddrc *priv = dev_get_drvdata(dev);
+
+	priv->resume_rate = clk_get_rate(priv->dram_core);
+
+	return imx8m_ddrc_target(dev, &priv->suspend_rate, 0);
+}
+
+static int imx8m_ddrc_resume(struct device *dev)
+{
+	struct imx8m_ddrc *priv = dev_get_drvdata(dev);
+
+	return imx8m_ddrc_target(dev, &priv->resume_rate, 0);
+}
+
 static int imx8m_ddrc_get_cur_freq(struct device *dev, unsigned long *freq)
 {
 	struct imx8m_ddrc *priv = dev_get_drvdata(dev);
@@ -336,6 +354,9 @@ static int imx8m_ddrc_init_freq_info(struct device *dev)
 
 		if (dev_pm_opp_add(dev, freq->rate * 250000, 0))
 			return -ENODEV;
+
+		if (index ==  0)
+			priv->suspend_rate = freq->rate * 250000;
 	}
 
 	return 0;
@@ -412,10 +433,15 @@ static const struct of_device_id imx8m_ddrc_of_match[] = {
 };
 MODULE_DEVICE_TABLE(of, imx8m_ddrc_of_match);
 
+static const struct dev_pm_ops imx8m_ddrc_pm_ops = {
+	SET_LATE_SYSTEM_SLEEP_PM_OPS(imx8m_ddrc_suspend, imx8m_ddrc_resume)
+};
+
 static struct platform_driver imx8m_ddrc_platdrv = {
 	.probe		= imx8m_ddrc_probe,
 	.driver = {
 		.name	= "imx8m-ddrc-devfreq",
+		.pm = &imx8m_ddrc_pm_ops,
 		.of_match_table = of_match_ptr(imx8m_ddrc_of_match),
 	},
 };
-- 
2.29.2