regulator: core: Add debugfs to show constraint flags

There are debugfs entries for voltage and current, but not for
the constraint flags. It's useful for debugging to be able to
see what these flags are so this patch adds a new debugfs file.
We can't use debugfs_create_bool for this because the flags are
bitfields, so as this needs a special read callback they have been
collected into a single file that lists all the flags.

Signed-off-by: Richard Fitzgerald <rf@opensource.wolfsonmicro.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/regulator/core.c

@@ -1272,6 +1272,55 @@ static void unset_regulator_supplies(struct regulator_dev *rdev)
 	}
 }
 
+#ifdef CONFIG_DEBUG_FS
+static ssize_t constraint_flags_read_file(struct file *file,
+					  char __user *user_buf,
+					  size_t count, loff_t *ppos)
+{
+	const struct regulator *regulator = file->private_data;
+	const struct regulation_constraints *c = regulator->rdev->constraints;
+	char *buf;
+	ssize_t ret;
+
+	if (!c)
+		return 0;
+
+	buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	ret = snprintf(buf, PAGE_SIZE,
+			"always_on: %u\n"
+			"boot_on: %u\n"
+			"apply_uV: %u\n"
+			"ramp_disable: %u\n"
+			"soft_start: %u\n"
+			"pull_down: %u\n"
+			"over_current_protection: %u\n",
+			c->always_on,
+			c->boot_on,
+			c->apply_uV,
+			c->ramp_disable,
+			c->soft_start,
+			c->pull_down,
+			c->over_current_protection);
+
+	ret = simple_read_from_buffer(user_buf, count, ppos, buf, ret);
+	kfree(buf);
+
+	return ret;
+}
+
+#endif
+
+static const struct file_operations constraint_flags_fops = {
+#ifdef CONFIG_DEBUG_FS
+	.open = simple_open,
+	.read = constraint_flags_read_file,
+	.llseek = default_llseek,
+#endif
+};
+
 #define REG_STR_SIZE	64
 
 static struct regulator *create_regulator(struct regulator_dev *rdev,
@@ -1327,6 +1376,9 @@ static struct regulator *create_regulator(struct regulator_dev *rdev,
 				   &regulator->min_uV);
 		debugfs_create_u32("max_uV", 0444, regulator->debugfs,
 				   &regulator->max_uV);
+		debugfs_create_file("constraint_flags", 0444,
+				    regulator->debugfs, regulator,
+				    &constraint_flags_fops);
 	}
 
 	/*