drm/i915/params: add i915 parameters to debugfs

Add a debugfs subdirectory i915_params with all the i915 module
parameters. This is a first step, with lots of boilerplate, and not much
benefit yet.

This will result in a new device specific debugfs directory at
/sys/kernel/debug/dri/<N>/i915_params duplicating the module specific
sysfs directory at /sys/module/i915/parameters/. Going forward, all
users of the parameters should use the debugfs, with the module
parameters being phased out.

Add debugfs permissions to I915_PARAMS_FOR_EACH(). This duplicates the
mode with module parameter sysfs, but the goal is to make the module
parameters read-only initial values for device specific parameters.

0 mode will bypass debugfs creation. Use it for verbose_state_checks
which will need special attention in follow-up work.

Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/600101c8433e7caf9303663fc85a9972fa1f05e7.1575560168.git.jani.nikula@intel.com

1 files changed, 233 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/i915_debugfs_params.c b/drivers/gpu/drm/i915/i915_debugfs_params.c
new file mode 100644
index 000000000000..7f1af5a35ca1
--- /dev/null
+++ b/drivers/gpu/drm/i915/i915_debugfs_params.c
@@ -0,0 +1,233 @@
+// SPDX-License-Identifier: MIT
+/*
+ * Copyright © 2019 Intel Corporation
+ */
+
+#include <linux/kernel.h>
+
+#include "i915_drv.h"
+#include "i915_params.h"
+
+/* int param */
+static int i915_param_int_show(struct seq_file *m, void *data)
+{
+	int *value = m->private;
+
+	seq_printf(m, "%d\n", *value);
+
+	return 0;
+}
+
+static int i915_param_int_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, i915_param_int_show, inode->i_private);
+}
+
+static ssize_t i915_param_int_write(struct file *file,
+				    const char __user *ubuf, size_t len,
+				    loff_t *offp)
+{
+	struct seq_file *m = file->private_data;
+	int *value = m->private;
+	int ret;
+
+	ret = kstrtoint_from_user(ubuf, len, 0, value);
+
+	return ret ?: len;
+}
+
+static const struct file_operations i915_param_int_fops = {
+	.owner = THIS_MODULE,
+	.open = i915_param_int_open,
+	.read = seq_read,
+	.write = i915_param_int_write,
+	.llseek = default_llseek,
+	.release = single_release,
+};
+
+static const struct file_operations i915_param_int_fops_ro = {
+	.owner = THIS_MODULE,
+	.open = i915_param_int_open,
+	.read = seq_read,
+	.llseek = default_llseek,
+	.release = single_release,
+};
+
+/* unsigned int param */
+static int i915_param_uint_show(struct seq_file *m, void *data)
+{
+	unsigned int *value = m->private;
+
+	seq_printf(m, "%u\n", *value);
+
+	return 0;
+}
+
+static int i915_param_uint_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, i915_param_uint_show, inode->i_private);
+}
+
+static ssize_t i915_param_uint_write(struct file *file,
+				     const char __user *ubuf, size_t len,
+				     loff_t *offp)
+{
+	struct seq_file *m = file->private_data;
+	unsigned int *value = m->private;
+	int ret;
+
+	ret = kstrtouint_from_user(ubuf, len, 0, value);
+
+	return ret ?: len;
+}
+
+static const struct file_operations i915_param_uint_fops = {
+	.owner = THIS_MODULE,
+	.open = i915_param_uint_open,
+	.read = seq_read,
+	.write = i915_param_uint_write,
+	.llseek = default_llseek,
+	.release = single_release,
+};
+
+static const struct file_operations i915_param_uint_fops_ro = {
+	.owner = THIS_MODULE,
+	.open = i915_param_uint_open,
+	.read = seq_read,
+	.llseek = default_llseek,
+	.release = single_release,
+};
+
+/* char * param */
+static int i915_param_charp_show(struct seq_file *m, void *data)
+{
+	const char **s = m->private;
+
+	seq_printf(m, "%s\n", *s);
+
+	return 0;
+}
+
+static int i915_param_charp_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, i915_param_charp_show, inode->i_private);
+}
+
+static ssize_t i915_param_charp_write(struct file *file,
+				      const char __user *ubuf, size_t len,
+				      loff_t *offp)
+{
+	struct seq_file *m = file->private_data;
+	char **s = m->private;
+	char *new, *old;
+
+	/* FIXME: remove locking after params aren't the module params */
+	kernel_param_lock(THIS_MODULE);
+
+	old = *s;
+	new = strndup_user(ubuf, PAGE_SIZE);
+	if (IS_ERR(new)) {
+		len = PTR_ERR(new);
+		goto out;
+	}
+
+	*s = new;
+
+	kfree(old);
+out:
+	kernel_param_unlock(THIS_MODULE);
+
+	return len;
+}
+
+static const struct file_operations i915_param_charp_fops = {
+	.owner = THIS_MODULE,
+	.open = i915_param_charp_open,
+	.read = seq_read,
+	.write = i915_param_charp_write,
+	.llseek = default_llseek,
+	.release = single_release,
+};
+
+static const struct file_operations i915_param_charp_fops_ro = {
+	.owner = THIS_MODULE,
+	.open = i915_param_charp_open,
+	.read = seq_read,
+	.llseek = default_llseek,
+	.release = single_release,
+};
+
+#define RO(mode) (((mode) & 0222) == 0)
+
+static struct dentry *
+i915_debugfs_create_int(const char *name, umode_t mode,
+			struct dentry *parent, int *value)
+{
+	return debugfs_create_file_unsafe(name, mode, parent, value,
+					  RO(mode) ? &i915_param_int_fops_ro :
+					  &i915_param_int_fops);
+}
+
+static struct dentry *
+i915_debugfs_create_uint(const char *name, umode_t mode,
+			 struct dentry *parent, unsigned int *value)
+{
+	return debugfs_create_file_unsafe(name, mode, parent, value,
+					  RO(mode) ? &i915_param_uint_fops_ro :
+					  &i915_param_uint_fops);
+}
+
+static struct dentry *
+i915_debugfs_create_charp(const char *name, umode_t mode,
+			  struct dentry *parent, char **value)
+{
+	return debugfs_create_file(name, mode, parent, value,
+				   RO(mode) ? &i915_param_charp_fops_ro :
+				   &i915_param_charp_fops);
+}
+
+static __always_inline void
+_i915_param_create_file(struct dentry *parent, const char *name,
+			const char *type, int mode, void *value)
+{
+	if (!mode)
+		return;
+
+	if (!__builtin_strcmp(type, "bool"))
+		debugfs_create_bool(name, mode, parent, value);
+	else if (!__builtin_strcmp(type, "int"))
+		i915_debugfs_create_int(name, mode, parent, value);
+	else if (!__builtin_strcmp(type, "unsigned int"))
+		i915_debugfs_create_uint(name, mode, parent, value);
+	else if (!__builtin_strcmp(type, "unsigned long"))
+		debugfs_create_ulong(name, mode, parent, value);
+	else if (!__builtin_strcmp(type, "char *"))
+		i915_debugfs_create_charp(name, mode, parent, value);
+	else
+		WARN(1, "no debugfs fops defined for param type %s (i915.%s)\n",
+		     type, name);
+}
+
+/* add a subdirectory with files for each i915 param */
+struct dentry *i915_debugfs_params(struct drm_i915_private *i915)
+{
+	struct drm_minor *minor = i915->drm.primary;
+	struct i915_params *params = &i915_modparams;
+	struct dentry *dir;
+
+	dir = debugfs_create_dir("i915_params", minor->debugfs_root);
+	if (IS_ERR(dir))
+		return dir;
+
+	/*
+	 * Note: We could create files for params needing special handling
+	 * here. Set mode in params to 0 to skip the generic create file, or
+	 * just let the generic create file fail silently with -EEXIST.
+	 */
+
+#define REGISTER(T, x, unused, mode, ...) _i915_param_create_file(dir, #x, #T, mode, &params->x);
+	I915_PARAMS_FOR_EACH(REGISTER);
+#undef REGISTER
+
+	return dir;
+}