1 files changed, 91 insertions, 125 deletions

diff --git a/drivers/char/hw_random/timeriomem-rng.c b/drivers/char/hw_random/timeriomem-rng.c
index d2120ba8f3f9..e61f06393209 100644
--- a/drivers/char/hw_random/timeriomem-rng.c
+++ b/drivers/char/hw_random/timeriomem-rng.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-only
 /*
  * drivers/char/hw_random/timeriomem-rng.c
  *
@@ -7,10 +8,6 @@
  *   Copyright 2005 (c) MontaVista Software, Inc.
  *   Author: Deepak Saxena <dsaxena@plexity.net>
  *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation.
- *
  * Overview:
  *   This driver is useful for platforms that have an IO range that provides
  *   periodic random data from a single IO memory address.  All the platform
@@ -20,84 +17,93 @@
  * TODO: add support for reading sizes other than 32bits and masking
  */
 
-#include <linux/module.h>
-#include <linux/kernel.h>
-#include <linux/platform_device.h>
-#include <linux/of.h>
+#include <linux/completion.h>
+#include <linux/delay.h>
+#include <linux/hrtimer.h>
 #include <linux/hw_random.h>
 #include <linux/io.h>
+#include <linux/ktime.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
 #include <linux/slab.h>
+#include <linux/time.h>
 #include <linux/timeriomem-rng.h>
-#include <linux/jiffies.h>
-#include <linux/sched.h>
-#include <linux/timer.h>
-#include <linux/completion.h>
 
-struct timeriomem_rng_private_data {
+struct timeriomem_rng_private {
 	void __iomem		*io_base;
-	unsigned int		expires;
-	unsigned int		period;
+	ktime_t			period;
 	unsigned int		present:1;
 
-	struct timer_list	timer;
+	struct hrtimer		timer;
 	struct completion	completion;
 
-	struct hwrng		timeriomem_rng_ops;
+	struct hwrng		rng_ops;
 };
 
-#define to_rng_priv(rng) \
-		((struct timeriomem_rng_private_data *)rng->priv)
-
-/*
- * have data return 1, however return 0 if we have nothing
- */
-static int timeriomem_rng_data_present(struct hwrng *rng, int wait)
+static int timeriomem_rng_read(struct hwrng *hwrng, void *data,
+				size_t max, bool wait)
 {
-	struct timeriomem_rng_private_data *priv = to_rng_priv(rng);
-
-	if (!wait || priv->present)
-		return priv->present;
+	struct timeriomem_rng_private *priv =
+		container_of(hwrng, struct timeriomem_rng_private, rng_ops);
+	int retval = 0;
+	int period_us = ktime_to_us(priv->period);
+
+	/*
+	 * There may not have been enough time for new data to be generated
+	 * since the last request.  If the caller doesn't want to wait, let them
+	 * bail out.  Otherwise, wait for the completion.  If the new data has
+	 * already been generated, the completion should already be available.
+	 */
+	if (!wait && !priv->present)
+		return 0;
 
 	wait_for_completion(&priv->completion);
 
-	return 1;
-}
-
-static int timeriomem_rng_data_read(struct hwrng *rng, u32 *data)
-{
-	struct timeriomem_rng_private_data *priv = to_rng_priv(rng);
-	unsigned long cur;
-	s32 delay;
-
-	*data = readl(priv->io_base);
-
-	cur = jiffies;
-
-	delay = cur - priv->expires;
-	delay = priv->period - (delay % priv->period);
-
-	priv->expires = cur + delay;
+	do {
+		/*
+		 * After the first read, all additional reads will need to wait
+		 * for the RNG to generate new data.  Since the period can have
+		 * a wide range of values (1us to 1s have been observed), allow
+		 * for 1% tolerance in the sleep time rather than a fixed value.
+		 */
+		if (retval > 0)
+			usleep_range(period_us,
+					period_us + max(1, period_us / 100));
+
+		*(u32 *)data = readl(priv->io_base);
+		retval += sizeof(u32);
+		data += sizeof(u32);
+		max -= sizeof(u32);
+	} while (wait && max > sizeof(u32));
+
+	/*
+	 * Block any new callers until the RNG has had time to generate new
+	 * data.
+	 */
 	priv->present = 0;
+	reinit_completion(&priv->completion);
+	hrtimer_forward_now(&priv->timer, priv->period);
+	hrtimer_restart(&priv->timer);
 
-	INIT_COMPLETION(priv->completion);
-	mod_timer(&priv->timer, priv->expires);
-
-	return 4;
+	return retval;
 }
 
-static void timeriomem_rng_trigger(unsigned long data)
+static enum hrtimer_restart timeriomem_rng_trigger(struct hrtimer *timer)
 {
-	struct timeriomem_rng_private_data *priv
-			= (struct timeriomem_rng_private_data *)data;
+	struct timeriomem_rng_private *priv
+		= container_of(timer, struct timeriomem_rng_private, timer);
 
 	priv->present = 1;
 	complete(&priv->completion);
+
+	return HRTIMER_NORESTART;
 }
 
 static int timeriomem_rng_probe(struct platform_device *pdev)
 {
 	struct timeriomem_rng_data *pdata = pdev->dev.platform_data;
-	struct timeriomem_rng_private_data *priv;
+	struct timeriomem_rng_private *priv;
 	struct resource *res;
 	int err = 0;
 	int period;
@@ -107,25 +113,24 @@ static int timeriomem_rng_probe(struct platform_device *pdev)
 		return -EINVAL;
 	}
 
-	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
-	if (!res)
-		return -ENXIO;
-
-	if (res->start % 4 != 0 || resource_size(res) != 4) {
-		dev_err(&pdev->dev,
-			"address must be four bytes wide and aligned\n");
-		return -EINVAL;
-	}
-
 	/* Allocate memory for the device structure (and zero it) */
-	priv = kzalloc(sizeof(struct timeriomem_rng_private_data), GFP_KERNEL);
-	if (!priv) {
-		dev_err(&pdev->dev, "failed to allocate device structure.\n");
+	priv = devm_kzalloc(&pdev->dev,
+			sizeof(struct timeriomem_rng_private), GFP_KERNEL);
+	if (!priv)
 		return -ENOMEM;
-	}
 
 	platform_set_drvdata(pdev, priv);
 
+	priv->io_base = devm_platform_get_and_ioremap_resource(pdev, 0, &res);
+	if (IS_ERR(priv->io_base))
+		return PTR_ERR(priv->io_base);
+
+	if (res->start % 4 != 0 || resource_size(res) < 4) {
+		dev_err(&pdev->dev,
+			"address must be at least four bytes wide and 32-bit aligned\n");
+		return -EINVAL;
+	}
+
 	if (pdev->dev.of_node) {
 		int i;
 
@@ -134,83 +139,45 @@ static int timeriomem_rng_probe(struct platform_device *pdev)
 			period = i;
 		else {
 			dev_err(&pdev->dev, "missing period\n");
-			err = -EINVAL;
-			goto out_free;
+			return -EINVAL;
 		}
-	} else
-		period = pdata->period;
 
-	priv->period = usecs_to_jiffies(period);
-	if (priv->period < 1) {
-		dev_err(&pdev->dev, "period is less than one jiffy\n");
-		err = -EINVAL;
-		goto out_free;
+		if (!of_property_read_u32(pdev->dev.of_node,
+						"quality", &i))
+			priv->rng_ops.quality = i;
+	} else {
+		period = pdata->period;
+		priv->rng_ops.quality = pdata->quality;
 	}
 
-	priv->expires	= jiffies;
-	priv->present	= 1;
-
+	priv->period = us_to_ktime(period);
 	init_completion(&priv->completion);
-	complete(&priv->completion);
+	hrtimer_setup(&priv->timer, timeriomem_rng_trigger, CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
 
-	setup_timer(&priv->timer, timeriomem_rng_trigger, (unsigned long)priv);
+	priv->rng_ops.name = dev_name(&pdev->dev);
+	priv->rng_ops.read = timeriomem_rng_read;
 
-	priv->timeriomem_rng_ops.name		= dev_name(&pdev->dev);
-	priv->timeriomem_rng_ops.data_present	= timeriomem_rng_data_present;
-	priv->timeriomem_rng_ops.data_read	= timeriomem_rng_data_read;
-	priv->timeriomem_rng_ops.priv		= (unsigned long)priv;
-
-	if (!request_mem_region(res->start, resource_size(res),
-				dev_name(&pdev->dev))) {
-		dev_err(&pdev->dev, "request_mem_region failed\n");
-		err = -EBUSY;
-		goto out_timer;
-	}
-
-	priv->io_base = ioremap(res->start, resource_size(res));
-	if (priv->io_base == NULL) {
-		dev_err(&pdev->dev, "ioremap failed\n");
-		err = -EIO;
-		goto out_release_io;
-	}
+	/* Assume random data is already available. */
+	priv->present = 1;
+	complete(&priv->completion);
 
-	err = hwrng_register(&priv->timeriomem_rng_ops);
+	err = devm_hwrng_register(&pdev->dev, &priv->rng_ops);
 	if (err) {
 		dev_err(&pdev->dev, "problem registering\n");
-		goto out;
+		return err;
 	}
 
 	dev_info(&pdev->dev, "32bits from 0x%p @ %dus\n",
 			priv->io_base, period);
 
 	return 0;
-
-out:
-	iounmap(priv->io_base);
-out_release_io:
-	release_mem_region(res->start, resource_size(res));
-out_timer:
-	del_timer_sync(&priv->timer);
-out_free:
-	kfree(priv);
-	return err;
 }
 
-static int timeriomem_rng_remove(struct platform_device *pdev)
+static void timeriomem_rng_remove(struct platform_device *pdev)
 {
-	struct timeriomem_rng_private_data *priv = platform_get_drvdata(pdev);
-	struct resource *res;
-
-	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	struct timeriomem_rng_private *priv = platform_get_drvdata(pdev);
 
-	hwrng_unregister(&priv->timeriomem_rng_ops);
-
-	del_timer_sync(&priv->timer);
-	iounmap(priv->io_base);
-	release_mem_region(res->start, resource_size(res));
-	kfree(priv);
-
-	return 0;
+	hrtimer_cancel(&priv->timer);
 }
 
 static const struct of_device_id timeriomem_rng_match[] = {
@@ -222,7 +189,6 @@ MODULE_DEVICE_TABLE(of, timeriomem_rng_match);
 static struct platform_driver timeriomem_rng_driver = {
 	.driver = {
 		.name		= "timeriomem_rng",
-		.owner		= THIS_MODULE,
 		.of_match_table	= timeriomem_rng_match,
 	},
 	.probe		= timeriomem_rng_probe,