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Date:   Fri, 14 Aug 2020 03:05:58 +0300
From:   Dmitry Osipenko <digetx@...il.com>
To:     Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Georgi Djakov <georgi.djakov@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Peter De Schrijver <pdeschrijver@...dia.com>,
        MyungJoo Ham <myungjoo.ham@...sung.com>,
        Kyungmin Park <kyungmin.park@...sung.com>,
        Chanwoo Choi <cw00.choi@...sung.com>,
        Mikko Perttunen <cyndis@...si.fi>
Cc:     linux-tegra@...r.kernel.org, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        devicetree@...r.kernel.org
Subject: [PATCH v5 13/36] PM / devfreq: tegra30: Use MC timings for building OPP table

The clk_round_rate() won't be usable for building OPP table once
interconnect support will be added to the EMC driver because that CLK API
function limits the rounded rate based on the clk rate that is imposed by
active clk-users, and thus, the rounding won't work as expected if
interconnect will set the minimum EMC clock rate before devfreq driver is
loaded. The struct tegra_mc contains memory timings which could be used by
the devfreq driver for building up OPP table instead of rounding clock
rate, this patch implements this idea.

Signed-off-by: Dmitry Osipenko <digetx@...il.com>
---
 drivers/devfreq/tegra30-devfreq.c | 93 +++++++++++++++++++++----------
 1 file changed, 65 insertions(+), 28 deletions(-)

diff --git a/drivers/devfreq/tegra30-devfreq.c b/drivers/devfreq/tegra30-devfreq.c
index 423dd35c95b3..6c2f56b34535 100644
--- a/drivers/devfreq/tegra30-devfreq.c
+++ b/drivers/devfreq/tegra30-devfreq.c
@@ -19,6 +19,8 @@
 #include <linux/reset.h>
 #include <linux/workqueue.h>
 
+#include <soc/tegra/mc.h>
+
 #include "governor.h"
 
 #define ACTMON_GLB_STATUS					0x0
@@ -153,6 +155,18 @@ struct tegra_devfreq_device {
 	unsigned long target_freq;
 };
 
+struct tegra_devfreq_soc_data {
+	const char *mc_compatible;
+};
+
+static const struct tegra_devfreq_soc_data tegra30_soc = {
+	.mc_compatible = "nvidia,tegra30-mc",
+};
+
+static const struct tegra_devfreq_soc_data tegra124_soc = {
+	.mc_compatible = "nvidia,tegra124-mc",
+};
+
 struct tegra_devfreq {
 	struct devfreq		*devfreq;
 
@@ -771,15 +785,49 @@ static struct devfreq_governor tegra_devfreq_governor = {
 	.interrupt_driven = true,
 };
 
+static struct tegra_mc *tegra_get_memory_controller(const char *compatible)
+{
+	struct platform_device *pdev;
+	struct device_node *np;
+	struct tegra_mc *mc;
+
+	np = of_find_compatible_node(NULL, NULL, compatible);
+	if (!np)
+		return ERR_PTR(-ENOENT);
+
+	pdev = of_find_device_by_node(np);
+	of_node_put(np);
+	if (!pdev)
+		return ERR_PTR(-ENODEV);
+
+	mc = platform_get_drvdata(pdev);
+	if (!mc)
+		return ERR_PTR(-EPROBE_DEFER);
+
+	return mc;
+}
+
 static int tegra_devfreq_probe(struct platform_device *pdev)
 {
+	const struct tegra_devfreq_soc_data *soc_data;
 	struct tegra_devfreq_device *dev;
 	struct tegra_devfreq *tegra;
 	struct devfreq *devfreq;
+	struct tegra_mc *mc;
 	unsigned int i;
-	long rate;
 	int err;
 
+	soc_data = of_device_get_match_data(&pdev->dev);
+
+	mc = tegra_get_memory_controller(soc_data->mc_compatible);
+	if (IS_ERR(mc))
+		return PTR_ERR(mc);
+
+	if (!mc->num_timings) {
+		dev_info(&pdev->dev, "memory controller has no timings\n");
+		return -ENODEV;
+	}
+
 	tegra = devm_kzalloc(&pdev->dev, sizeof(*tegra), GFP_KERNEL);
 	if (!tegra)
 		return -ENOMEM;
@@ -825,6 +873,20 @@ static int tegra_devfreq_probe(struct platform_device *pdev)
 		return err;
 	}
 
+	for (i = 0; i < mc->num_timings; i++) {
+		/*
+		 * Memory Controller timings are sorted in ascending clock
+		 * rate order, so the last timing will be the max freq.
+		 */
+		tegra->max_freq = mc->timings[i].rate / KHZ;
+
+		err = dev_pm_opp_add(&pdev->dev, tegra->max_freq, 0);
+		if (err) {
+			dev_err(&pdev->dev, "Failed to add OPP: %d\n", err);
+			goto remove_opps;
+		}
+	}
+
 	reset_control_assert(tegra->reset);
 
 	err = clk_prepare_enable(tegra->clock);
@@ -836,37 +898,12 @@ static int tegra_devfreq_probe(struct platform_device *pdev)
 
 	reset_control_deassert(tegra->reset);
 
-	rate = clk_round_rate(tegra->emc_clock, ULONG_MAX);
-	if (rate < 0) {
-		dev_err(&pdev->dev, "Failed to round clock rate: %ld\n", rate);
-		return rate;
-	}
-
-	tegra->max_freq = rate / KHZ;
-
 	for (i = 0; i < ARRAY_SIZE(actmon_device_configs); i++) {
 		dev = tegra->devices + i;
 		dev->config = actmon_device_configs + i;
 		dev->regs = tegra->regs + dev->config->offset;
 	}
 
-	for (rate = 0; rate <= tegra->max_freq * KHZ; rate++) {
-		rate = clk_round_rate(tegra->emc_clock, rate);
-
-		if (rate < 0) {
-			dev_err(&pdev->dev,
-				"Failed to round clock rate: %ld\n", rate);
-			err = rate;
-			goto remove_opps;
-		}
-
-		err = dev_pm_opp_add(&pdev->dev, rate / KHZ, 0);
-		if (err) {
-			dev_err(&pdev->dev, "Failed to add OPP: %d\n", err);
-			goto remove_opps;
-		}
-	}
-
 	platform_set_drvdata(pdev, tegra);
 
 	tegra->clk_rate_change_nb.notifier_call = tegra_actmon_clk_notify_cb;
@@ -921,8 +958,8 @@ static int tegra_devfreq_remove(struct platform_device *pdev)
 }
 
 static const struct of_device_id tegra_devfreq_of_match[] = {
-	{ .compatible = "nvidia,tegra30-actmon" },
-	{ .compatible = "nvidia,tegra124-actmon" },
+	{ .compatible = "nvidia,tegra30-actmon",  .data = &tegra30_soc, },
+	{ .compatible = "nvidia,tegra124-actmon", .data = &tegra124_soc, },
 	{ },
 };
 
-- 
2.27.0

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