diff options
Diffstat (limited to 'drivers/memory/tegra/tegra20-emc.c')
| -rw-r--r-- | drivers/memory/tegra/tegra20-emc.c | 175 |
1 files changed, 175 insertions, 0 deletions
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: |