1 files changed, 293 insertions, 0 deletions
diff --git a/drivers/memory/tegra/tegra186-emc.c b/drivers/memory/tegra/tegra186-emc.c
new file mode 100644
index 000000000000..97f26bc77ad4
--- /dev/null
+++ b/drivers/memory/tegra/tegra186-emc.c
@@ -0,0 +1,293 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2019 NVIDIA CORPORATION.  All rights reserved.
+ */
+
+#include <linux/clk.h>
+#include <linux/debugfs.h>
+#include <linux/module.h>
+#include <linux/mod_devicetable.h>
+#include <linux/platform_device.h>
+
+#include <soc/tegra/bpmp.h>
+
+struct tegra186_emc_dvfs {
+	unsigned long latency;
+	unsigned long rate;
+};
+
+struct tegra186_emc {
+	struct tegra_bpmp *bpmp;
+	struct device *dev;
+	struct clk *clk;
+
+	struct tegra186_emc_dvfs *dvfs;
+	unsigned int num_dvfs;
+
+	struct {
+		struct dentry *root;
+		unsigned long min_rate;
+		unsigned long max_rate;
+	} debugfs;
+};
+
+/*
+ * debugfs interface
+ *
+ * The memory controller driver exposes some files in debugfs that can be used
+ * to control the EMC frequency. The top-level directory can be found here:
+ *
+ *   /sys/kernel/debug/emc
+ *
+ * It contains the following files:
+ *
+ *   - available_rates: This file contains a list of valid, space-separated
+ *     EMC frequencies.
+ *
+ *   - min_rate: Writing a value to this file sets the given frequency as the
+ *       floor of the permitted range. If this is higher than the currently
+ *       configured EMC frequency, this will cause the frequency to be
+ *       increased so that it stays within the valid range.
+ *
+ *   - max_rate: Similarily to the min_rate file, writing a value to this file
+ *       sets the given frequency as the ceiling of the permitted range. If
+ *       the value is lower than the currently configured EMC frequency, this
+ *       will cause the frequency to be decreased so that it stays within the
+ *       valid range.
+ */
+
+static bool tegra186_emc_validate_rate(struct tegra186_emc *emc,
+				       unsigned long rate)
+{
+	unsigned int i;
+
+	for (i = 0; i < emc->num_dvfs; i++)
+		if (rate == emc->dvfs[i].rate)
+			return true;
+
+	return false;
+}
+
+static int tegra186_emc_debug_available_rates_show(struct seq_file *s,
+						   void *data)
+{
+	struct tegra186_emc *emc = s->private;
+	const char *prefix = "";
+	unsigned int i;
+
+	for (i = 0; i < emc->num_dvfs; i++) {
+		seq_printf(s, "%s%lu", prefix, emc->dvfs[i].rate);
+		prefix = " ";
+	}
+
+	seq_puts(s, "\n");
+
+	return 0;
+}
+
+static int tegra186_emc_debug_available_rates_open(struct inode *inode,
+						   struct file *file)
+{
+	return single_open(file, tegra186_emc_debug_available_rates_show,
+			   inode->i_private);
+}
+
+static const struct file_operations tegra186_emc_debug_available_rates_fops = {
+	.open = tegra186_emc_debug_available_rates_open,
+	.read = seq_read,
+	.llseek = seq_lseek,
+	.release = single_release,
+};
+
+static int tegra186_emc_debug_min_rate_get(void *data, u64 *rate)
+{
+	struct tegra186_emc *emc = data;
+
+	*rate = emc->debugfs.min_rate;
+
+	return 0;
+}
+
+static int tegra186_emc_debug_min_rate_set(void *data, u64 rate)
+{
+	struct tegra186_emc *emc = data;
+	int err;
+
+	if (!tegra186_emc_validate_rate(emc, rate))
+		return -EINVAL;
+
+	err = clk_set_min_rate(emc->clk, rate);
+	if (err < 0)
+		return err;
+
+	emc->debugfs.min_rate = rate;
+
+	return 0;
+}
+
+DEFINE_SIMPLE_ATTRIBUTE(tegra186_emc_debug_min_rate_fops,
+			tegra186_emc_debug_min_rate_get,
+			tegra186_emc_debug_min_rate_set, "%llu\n");
+
+static int tegra186_emc_debug_max_rate_get(void *data, u64 *rate)
+{
+	struct tegra186_emc *emc = data;
+
+	*rate = emc->debugfs.max_rate;
+
+	return 0;
+}
+
+static int tegra186_emc_debug_max_rate_set(void *data, u64 rate)
+{
+	struct tegra186_emc *emc = data;
+	int err;
+
+	if (!tegra186_emc_validate_rate(emc, rate))
+		return -EINVAL;
+
+	err = clk_set_max_rate(emc->clk, rate);
+	if (err < 0)
+		return err;
+
+	emc->debugfs.max_rate = rate;
+
+	return 0;
+}
+
+DEFINE_SIMPLE_ATTRIBUTE(tegra186_emc_debug_max_rate_fops,
+			tegra186_emc_debug_max_rate_get,
+			tegra186_emc_debug_max_rate_set, "%llu\n");
+
+static int tegra186_emc_probe(struct platform_device *pdev)
+{
+	struct mrq_emc_dvfs_latency_response response;
+	struct tegra_bpmp_message msg;
+	struct tegra186_emc *emc;
+	unsigned int i;
+	int err;
+
+	emc = devm_kzalloc(&pdev->dev, sizeof(*emc), GFP_KERNEL);
+	if (!emc)
+		return -ENOMEM;
+
+	emc->bpmp = tegra_bpmp_get(&pdev->dev);
+	if (IS_ERR(emc->bpmp)) {
+		err = PTR_ERR(emc->bpmp);
+
+		if (err != -EPROBE_DEFER)
+			dev_err(&pdev->dev, "failed to get BPMP: %d\n", err);
+
+		return err;
+	}
+
+	emc->clk = devm_clk_get(&pdev->dev, "emc");
+	if (IS_ERR(emc->clk)) {
+		err = PTR_ERR(emc->clk);
+		dev_err(&pdev->dev, "failed to get EMC clock: %d\n", err);
+		return err;
+	}
+
+	platform_set_drvdata(pdev, emc);
+	emc->dev = &pdev->dev;
+
+	memset(&msg, 0, sizeof(msg));
+	msg.mrq = MRQ_EMC_DVFS_LATENCY;
+	msg.tx.data = NULL;
+	msg.tx.size = 0;
+	msg.rx.data = &response;
+	msg.rx.size = sizeof(response);
+
+	err = tegra_bpmp_transfer(emc->bpmp, &msg);
+	if (err < 0) {
+		dev_err(&pdev->dev, "failed to EMC DVFS pairs: %d\n", err);
+		return err;
+	}
+
+	emc->debugfs.min_rate = ULONG_MAX;
+	emc->debugfs.max_rate = 0;
+
+	emc->num_dvfs = response.num_pairs;
+
+	emc->dvfs = devm_kmalloc_array(&pdev->dev, emc->num_dvfs,
+				       sizeof(*emc->dvfs), GFP_KERNEL);
+	if (!emc->dvfs)
+		return -ENOMEM;
+
+	dev_dbg(&pdev->dev, "%u DVFS pairs:\n", emc->num_dvfs);
+
+	for (i = 0; i < emc->num_dvfs; i++) {
+		emc->dvfs[i].rate = response.pairs[i].freq * 1000;
+		emc->dvfs[i].latency = response.pairs[i].latency;
+
+		if (emc->dvfs[i].rate < emc->debugfs.min_rate)
+			emc->debugfs.min_rate = emc->dvfs[i].rate;
+
+		if (emc->dvfs[i].rate > emc->debugfs.max_rate)
+			emc->debugfs.max_rate = emc->dvfs[i].rate;
+
+		dev_dbg(&pdev->dev, "  %2u: %lu Hz -> %lu us\n", i,
+			emc->dvfs[i].rate, emc->dvfs[i].latency);
+	}
+
+	err = clk_set_rate_range(emc->clk, emc->debugfs.min_rate,
+				 emc->debugfs.max_rate);
+	if (err < 0) {
+		dev_err(&pdev->dev,
+			"failed to set rate range [%lu-%lu] for %pC\n",
+			emc->debugfs.min_rate, emc->debugfs.max_rate,
+			emc->clk);
+		return err;
+	}
+
+	emc->debugfs.root = debugfs_create_dir("emc", NULL);
+	if (!emc->debugfs.root) {
+		dev_err(&pdev->dev, "failed to create debugfs directory\n");
+		return 0;
+	}
+
+	debugfs_create_file("available_rates", S_IRUGO, emc->debugfs.root,
+			    emc, &tegra186_emc_debug_available_rates_fops);
+	debugfs_create_file("min_rate", S_IRUGO | S_IWUSR, emc->debugfs.root,
+			    emc, &tegra186_emc_debug_min_rate_fops);
+	debugfs_create_file("max_rate", S_IRUGO | S_IWUSR, emc->debugfs.root,
+			    emc, &tegra186_emc_debug_max_rate_fops);
+
+	return 0;
+}
+
+static int tegra186_emc_remove(struct platform_device *pdev)
+{
+	struct tegra186_emc *emc = platform_get_drvdata(pdev);
+
+	debugfs_remove_recursive(emc->debugfs.root);
+	tegra_bpmp_put(emc->bpmp);
+
+	return 0;
+}
+
+static const struct of_device_id tegra186_emc_of_match[] = {
+#if defined(CONFIG_ARCH_TEGRA186_SOC)
+	{ .compatible = "nvidia,tegra186-emc" },
+#endif
+#if defined(CONFIG_ARCH_TEGRA194_SOC)
+	{ .compatible = "nvidia,tegra194-emc" },
+#endif
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, tegra186_emc_of_match);
+
+static struct platform_driver tegra186_emc_driver = {
+	.driver = {
+		.name = "tegra186-emc",
+		.of_match_table = tegra186_emc_of_match,
+		.suppress_bind_attrs = true,
+	},
+	.probe = tegra186_emc_probe,
+	.remove = tegra186_emc_remove,
+};
+module_platform_driver(tegra186_emc_driver);
+
+MODULE_AUTHOR("Thierry Reding <treding@nvidia.com>");
+MODULE_DESCRIPTION("NVIDIA Tegra186 External Memory Controller driver");
+MODULE_LICENSE("GPL v2");