1 files changed, 143 insertions, 42 deletions

diff --git a/drivers/memory/tegra/tegra124-emc.c b/drivers/memory/tegra/tegra124-emc.c
index 464f0ceaee63..21f05240682b 100644
--- a/drivers/memory/tegra/tegra124-emc.c
+++ b/drivers/memory/tegra/tegra124-emc.c
@@ -467,12 +467,20 @@ struct tegra_emc {
 
 	void __iomem *regs;
 
+	struct clk *clk;
+
 	enum emc_dram_type dram_type;
 	unsigned int dram_num;
 
 	struct emc_timing last_timing;
 	struct emc_timing *timings;
 	unsigned int num_timings;
+
+	struct {
+		struct dentry *root;
+		unsigned long min_rate;
+		unsigned long max_rate;
+	} debugfs;
 };
 
 /* Timing change sequence functions */
@@ -998,38 +1006,51 @@ tegra_emc_find_node_by_ram_code(struct device_node *node, u32 ram_code)
 	return NULL;
 }
 
-/* Debugfs entry */
+/*
+ * 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 int emc_debug_rate_get(void *data, u64 *rate)
+static bool tegra_emc_validate_rate(struct tegra_emc *emc, unsigned long rate)
 {
-	struct clk *c = data;
-
-	*rate = clk_get_rate(c);
-
-	return 0;
-}
+	unsigned int i;
 
-static int emc_debug_rate_set(void *data, u64 rate)
-{
-	struct clk *c = data;
+	for (i = 0; i < emc->num_timings; i++)
+		if (rate == emc->timings[i].rate)
+			return true;
 
-	return clk_set_rate(c, rate);
+	return false;
 }
 
-DEFINE_SIMPLE_ATTRIBUTE(emc_debug_rate_fops, emc_debug_rate_get,
-			emc_debug_rate_set, "%lld\n");
-
-static int emc_debug_supported_rates_show(struct seq_file *s, void *data)
+static int tegra_emc_debug_available_rates_show(struct seq_file *s,
+						void *data)
 {
 	struct tegra_emc *emc = s->private;
 	const char *prefix = "";
 	unsigned int i;
 
 	for (i = 0; i < emc->num_timings; i++) {
-		struct emc_timing *timing = &emc->timings[i];
-
-		seq_printf(s, "%s%lu", prefix, timing->rate);
-
+		seq_printf(s, "%s%lu", prefix, emc->timings[i].rate);
 		prefix = " ";
 	}
 
@@ -1038,46 +1059,126 @@ static int emc_debug_supported_rates_show(struct seq_file *s, void *data)
 	return 0;
 }
 
-static int emc_debug_supported_rates_open(struct inode *inode,
-					  struct file *file)
+static int tegra_emc_debug_available_rates_open(struct inode *inode,
+						struct file *file)
 {
-	return single_open(file, emc_debug_supported_rates_show,
+	return single_open(file, tegra_emc_debug_available_rates_show,
 			   inode->i_private);
 }
 
-static const struct file_operations emc_debug_supported_rates_fops = {
-	.open = emc_debug_supported_rates_open,
+static const struct file_operations tegra_emc_debug_available_rates_fops = {
+	.open = tegra_emc_debug_available_rates_open,
 	.read = seq_read,
 	.llseek = seq_lseek,
 	.release = single_release,
 };
 
+static int tegra_emc_debug_min_rate_get(void *data, u64 *rate)
+{
+	struct tegra_emc *emc = data;
+
+	*rate = emc->debugfs.min_rate;
+
+	return 0;
+}
+
+static int tegra_emc_debug_min_rate_set(void *data, u64 rate)
+{
+	struct tegra_emc *emc = data;
+	int err;
+
+	if (!tegra_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(tegra_emc_debug_min_rate_fops,
+			tegra_emc_debug_min_rate_get,
+			tegra_emc_debug_min_rate_set, "%llu\n");
+
+static int tegra_emc_debug_max_rate_get(void *data, u64 *rate)
+{
+	struct tegra_emc *emc = data;
+
+	*rate = emc->debugfs.max_rate;
+
+	return 0;
+}
+
+static int tegra_emc_debug_max_rate_set(void *data, u64 rate)
+{
+	struct tegra_emc *emc = data;
+	int err;
+
+	if (!tegra_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(tegra_emc_debug_max_rate_fops,
+			tegra_emc_debug_max_rate_get,
+			tegra_emc_debug_max_rate_set, "%llu\n");
+
 static void emc_debugfs_init(struct device *dev, struct tegra_emc *emc)
 {
-	struct dentry *root, *file;
-	struct clk *clk;
+	unsigned int i;
+	int err;
 
-	root = debugfs_create_dir("emc", NULL);
-	if (!root) {
-		dev_err(dev, "failed to create debugfs directory\n");
-		return;
+	emc->clk = devm_clk_get(dev, "emc");
+	if (IS_ERR(emc->clk)) {
+		if (PTR_ERR(emc->clk) != -ENODEV) {
+			dev_err(dev, "failed to get EMC clock: %ld\n",
+				PTR_ERR(emc->clk));
+			return;
+		}
 	}
 
-	clk = clk_get_sys("tegra-clk-debug", "emc");
-	if (IS_ERR(clk)) {
-		dev_err(dev, "failed to get debug clock: %ld\n", PTR_ERR(clk));
+	emc->debugfs.min_rate = ULONG_MAX;
+	emc->debugfs.max_rate = 0;
+
+	for (i = 0; i < emc->num_timings; i++) {
+		if (emc->timings[i].rate < emc->debugfs.min_rate)
+			emc->debugfs.min_rate = emc->timings[i].rate;
+
+		if (emc->timings[i].rate > emc->debugfs.max_rate)
+			emc->debugfs.max_rate = emc->timings[i].rate;
+	}
+
+	err = clk_set_rate_range(emc->clk, emc->debugfs.min_rate,
+				 emc->debugfs.max_rate);
+	if (err < 0) {
+		dev_err(dev, "failed to set rate range [%lu-%lu] for %pC\n",
+			emc->debugfs.min_rate, emc->debugfs.max_rate,
+			emc->clk);
 		return;
 	}
 
-	file = debugfs_create_file("rate", S_IRUGO | S_IWUSR, root, clk,
-				   &emc_debug_rate_fops);
-	if (!file)
-		dev_err(dev, "failed to create debugfs entry\n");
+	emc->debugfs.root = debugfs_create_dir("emc", NULL);
+	if (!emc->debugfs.root) {
+		dev_err(dev, "failed to create debugfs directory\n");
+		return;
+	}
 
-	file = debugfs_create_file("supported_rates", S_IRUGO, root, emc,
-				   &emc_debug_supported_rates_fops);
-	if (!file)
-		dev_err(dev, "failed to create debugfs entry\n");
+	debugfs_create_file("available_rates", S_IRUGO, emc->debugfs.root, emc,
+			    &tegra_emc_debug_available_rates_fops);
+	debugfs_create_file("min_rate", S_IRUGO | S_IWUSR, emc->debugfs.root,
+			    emc, &tegra_emc_debug_min_rate_fops);
+	debugfs_create_file("max_rate", S_IRUGO | S_IWUSR, emc->debugfs.root,
+			    emc, &tegra_emc_debug_max_rate_fops);
 }
 
 static int tegra_emc_probe(struct platform_device *pdev)