linux-kernel - [PATCH v3 09/39] memory: tegra20-emc: Initialize MC timings

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Date:   Sun,  7 Jun 2020 21:55:00 +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:     Artur Świgoń <a.swigon@...sung.com>,
        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 v3 09/39] memory: tegra20-emc: Initialize MC timings

We're going to add interconnect support to the EMC driver. Once this
support will be added, the Tegra20 devfreq driver will no longer be
able to use clk_round_rate(emc) for building up OPP table. It's quite
handy that struct tegra_mc contains memory timings which could be used
by the devfreq drivers instead of the clk rate-rounding. The tegra_mc
timings are populated by the MC driver only for Tegra30+ SoCs, hence
the Tegra20 EMC could populate timings by itself.

Signed-off-by: Dmitry Osipenko <digetx@...il.com>
---
 drivers/memory/tegra/tegra20-emc.c | 47 ++++++++++++++++++++++++++++++
 1 file changed, 47 insertions(+)

diff --git a/drivers/memory/tegra/tegra20-emc.c b/drivers/memory/tegra/tegra20-emc.c
index 035d9251e28a..a95522020a25 100644
--- a/drivers/memory/tegra/tegra20-emc.c
+++ b/drivers/memory/tegra/tegra20-emc.c
@@ -15,12 +15,15 @@
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/of.h>
+#include <linux/of_device.h>
 #include <linux/platform_device.h>
 #include <linux/sort.h>
 #include <linux/types.h>
 
 #include <soc/tegra/fuse.h>
 
+#include "mc.h"
+
 #define EMC_INTSTATUS				0x000
 #define EMC_INTMASK				0x004
 #define EMC_DBG					0x008
@@ -650,6 +653,38 @@ static void tegra_emc_debugfs_init(struct tegra_emc *emc)
 			    emc, &tegra_emc_debug_max_rate_fops);
 }
 
+static int tegra_emc_init_mc_timings(struct tegra_emc *emc)
+{
+	struct tegra_mc_timing *timing;
+	struct platform_device *pdev;
+	struct device_node *np;
+	struct tegra_mc *mc;
+	unsigned int i;
+
+	np = of_find_compatible_node(NULL, NULL, "nvidia,tegra20-mc-gart");
+	if (!np)
+		return -ENOENT;
+
+	pdev = of_find_device_by_node(np);
+	of_node_put(np);
+	if (!pdev)
+		return -ENOENT;
+
+	mc = platform_get_drvdata(pdev);
+	if (!mc)
+		return -EPROBE_DEFER;
+
+	mc->timings = devm_kcalloc(mc->dev, emc->num_timings, sizeof(*timing),
+				   GFP_KERNEL);
+	if (!mc->timings)
+		return -ENOMEM;
+
+	for (i = 0; i < emc->num_timings; i++)
+		mc->timings[mc->num_timings++].rate = emc->timings[i].rate;
+
+	return 0;
+}
+
 static int tegra_emc_probe(struct platform_device *pdev)
 {
 	struct device_node *np;
@@ -705,6 +740,18 @@ static int tegra_emc_probe(struct platform_device *pdev)
 		return err;
 	}
 
+	/*
+	 * Only Tegra30+ SoCs are having Memory Controller timings initialized
+	 * by the MC driver. For Tegra20 we need to populate the MC timings
+	 * from here. The MC timings will be used by the Tegra20 devfreq driver.
+	 */
+	err = tegra_emc_init_mc_timings(emc);
+	if (err) {
+		dev_err(&pdev->dev, "failed to initialize mc timings: %d\n",
+			err);
+		return err;
+	}
+
 	tegra20_clk_set_emc_round_callback(emc_round_rate, emc);
 
 	emc->clk = devm_clk_get(&pdev->dev, "emc");
-- 
2.26.0