Commit 8209eefa authored by Thierry Reding's avatar Thierry Reding
Browse files

memory: tegra: Implement EMC debugfs interface on Tegra20 



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: default avatarThierry Reding <treding@nvidia.com>
parent 6b9acd93

drivers/memory/tegra/tegra20-emc.c

+175 −0
Original line number Diff line number Diff line
@@ -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:

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