From: Thierry Reding <treding@xxxxxxxxxx>
A common debugfs interface is already available on Tegra124, Tegra186
and Tegra194. Implement the same interface on Tegra20 to enable testing
of the EMC frequency scaling code using a unified interface.
Signed-off-by: Thierry Reding <treding@xxxxxxxxxx>
---
drivers/memory/tegra/tegra20-emc.c | 175 +++++++++++++++++++++++++++++
1 file changed, 175 insertions(+)
diff --git a/drivers/memory/tegra/tegra20-emc.c b/drivers/memory/tegra/tegra20-emc.c
index 1b23b1c34476..8ae474d9bfb9 100644
--- a/drivers/memory/tegra/tegra20-emc.c
+++ b/drivers/memory/tegra/tegra20-emc.c
@@ -8,6 +8,7 @@
#include <linux/clk.h>
#include <linux/clk/tegra.h>
#include <linux/completion.h>
+#include <linux/debugfs.h>
#include <linux/err.h>
#include <linux/interrupt.h>
#include <linux/io.h>
@@ -150,6 +151,12 @@ struct tegra_emc {
struct emc_timing *timings;
unsigned int num_timings;
+
+ struct {
+ struct dentry *root;
+ unsigned long min_rate;
+ unsigned long max_rate;
+ } debugfs;
};
static irqreturn_t tegra_emc_isr(int irq, void *data)
@@ -478,6 +485,171 @@ static long emc_round_rate(unsigned long rate,
return timing->rate;
}
+/*
+ * 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 tegra_emc_validate_rate(struct tegra_emc *emc, unsigned long rate)
+{
+ unsigned int i;
+
+ for (i = 0; i < emc->num_timings; i++)
+ if (rate == emc->timings[i].rate)
+ return true;
+
+ return false;
+}
+
+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++) {
+ seq_printf(s, "%s%lu", prefix, emc->timings[i].rate);
+ prefix = " ";
+ }
+
+ seq_puts(s, "\n");
+
+ return 0;
+}
+
+static int tegra_emc_debug_available_rates_open(struct inode *inode,
+ struct file *file)
+{
+ return single_open(file, tegra_emc_debug_available_rates_show,
+ inode->i_private);
+}
+
+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 tegra_emc_debugfs_init(struct tegra_emc *emc)
+{
+ struct device *dev = emc->dev;
+ unsigned int i;
+ int err;
+
+ 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);
+ }
+
+ emc->debugfs.root = debugfs_create_dir("emc", NULL);
+ if (!emc->debugfs.root) {
+ dev_err(emc->dev, "failed to create debugfs directory\n");
+ return;
+ }
+
+ 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)
{
struct device_node *np;
@@ -550,6 +722,9 @@ static int tegra_emc_probe(struct platform_device *pdev)
goto unset_cb;
}
+ platform_set_drvdata(pdev, emc);
+ tegra_emc_debugfs_init(emc);
+
return 0;
unset_cb:
--
2.24.1
