memory: tegra: Implement EMC debugfs interface on Tegra30

A common debugfs interface is already available on Tegra20, Tegra124,
Tegra186 and Tegra194. Implement the same interface on Tegra30 to enable
testing of the EMC frequency scaling code using a unified interface.

Signed-off-by: Thierry Reding <treding@nvidia.com>

diff --git a/drivers/memory/tegra/tegra30-emc.c b/drivers/memory/tegra/tegra30-emc.c
index 0b6a5e451ea36ac682ce59332cf6e10d44815714..d61cb74cb52b00b5c1fb608ebed3553bfbc43134 100644 (file)
--- a/drivers/memory/tegra/tegra30-emc.c
+++ b/drivers/memory/tegra/tegra30-emc.c
@@ -12,6 +12,7 @@
 #include <linux/clk.h>
 #include <linux/clk/tegra.h>
 #include <linux/completion.h>
+#include <linux/debugfs.h>
 #include <linux/delay.h>
 #include <linux/err.h>
 #include <linux/interrupt.h>
@@ -347,6 +348,12 @@ struct tegra_emc {
        bool dll_on : 1;
        bool prepared : 1;
        bool bad_state : 1;
+
+       struct {
+               struct dentry *root;
+               unsigned long min_rate;
+               unsigned long max_rate;
+       } debugfs;
 };
 
 static irqreturn_t tegra_emc_isr(int irq, void *data)
@@ -1083,6 +1090,171 @@ 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 platform_device *mc;
@@ -1169,6 +1341,7 @@ static int tegra_emc_probe(struct platform_device *pdev)
        }
 
        platform_set_drvdata(pdev, emc);
+       tegra_emc_debugfs_init(emc);
 
        return 0;