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

[Dmitry Osipenko <digetx-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

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-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
---
 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