linux-kernel - [PATCH v5 09/36] memory: tegra20-emc: Initialize MC timings

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Date:   Fri, 14 Aug 2020 03:05:54 +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 09/36] 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/Kconfig       |  2 +-
 drivers/memory/tegra/tegra20-emc.c | 54 ++++++++++++++++++++++++++++++
 2 files changed, 55 insertions(+), 1 deletion(-)

diff --git a/drivers/memory/tegra/Kconfig b/drivers/memory/tegra/Kconfig
index c1cad4ce6251..5bf75b316a2f 100644
--- a/drivers/memory/tegra/Kconfig
+++ b/drivers/memory/tegra/Kconfig
@@ -10,7 +10,7 @@ config TEGRA_MC
 config TEGRA20_EMC
 	tristate "NVIDIA Tegra20 External Memory Controller driver"
 	default y
-	depends on ARCH_TEGRA_2x_SOC
+	depends on TEGRA_MC && ARCH_TEGRA_2x_SOC
 	help
 	  This driver is for the External Memory Controller (EMC) found on
 	  Tegra20 chips. The EMC controls the external DRAM on the board.
diff --git a/drivers/memory/tegra/tegra20-emc.c b/drivers/memory/tegra/tegra20-emc.c
index 5aa3a1da2975..a02ffc09c39e 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 +653,45 @@ 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;
+
+	if (!emc->num_timings)
+		return 0;
+
+	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;
+
+	/* shouldn't happen */
+	WARN_ON(mc->num_timings);
+	WARN_ON(mc->timings);
+
+	mc->timings = devm_kcalloc(emc->dev, emc->num_timings, sizeof(*timing),
+				   GFP_KERNEL);
+	if (!mc->timings)
+		return -ENOMEM;
+
+	for (i = 0; i < emc->num_timings; i++, mc->num_timings++)
+		mc->timings[i].rate = emc->timings[i].rate;
+
+	return 0;
+}
+
 static int tegra_emc_probe(struct platform_device *pdev)
 {
 	struct device_node *np;
@@ -721,6 +763,18 @@ static int tegra_emc_probe(struct platform_device *pdev)
 		goto unset_cb;
 	}
 
+	/*
+	 * 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);
+		goto unset_cb;
+	}
+
 	platform_set_drvdata(pdev, emc);
 	tegra_emc_debugfs_init(emc);
 
-- 
2.27.0