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[PATCH v2 0/3] hw_random: timeriomem_rng: Migrate to new API and improve performance

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  [PATCH v2 0/3] hw_random: timeriomem_rng: Migrate to new API and improve performance Rick Altherr <raltherr@google.com> - 2017-04-06 01:30 +0200
    [PATCH v2 1/3] hw_random: Migrate timeriomem_rng to new API Rick Altherr <raltherr@google.com> - 2017-04-06 01:30 +0200
    [PATCH v2 2/3] hw_random: timeriomem_rng: Shorten verbose type and variable names Rick Altherr <raltherr@google.com> - 2017-04-06 01:30 +0200
    Re: [PATCH v2 0/3] hw_random: timeriomem_rng: Migrate to new API and  improve performance Herbert Xu <herbert@gondor.apana.org.au> - 2017-04-10 13:30 +0200

#1617421 — [PATCH v2 0/3] hw_random: timeriomem_rng: Migrate to new API and improve performance

AST2400 can generate 32-bits of random data every 1us.  Original driver
was limited to one 32-bit read every jiffie due to deprecated API and use
of timers.  Migrating to new hwrng API and switching to hrtimers
improves read performance of /dev/hwrng to 13Mb/s.

Changes in v2:
- Split API migration into separate patch
- Split type and variable renames into separate patch
- Split performance improvements into separate patch

Rick Altherr (3):
  hw_random: Migrate timeriomem_rng to new API
  hw_random: timeriomem_rng: Shorten verbose type and variable names
  hw_random: timeriomem_rng: Improve performance for sub-jiffie update
    periods

 drivers/char/hw_random/timeriomem-rng.c | 157 ++++++++++++++++----------------
 1 file changed, 80 insertions(+), 77 deletions(-)

-- 
2.12.2.715.g7642488e1d-goog

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#1617422 — [PATCH v2 1/3] hw_random: Migrate timeriomem_rng to new API

Preserves the existing behavior of only returning 32-bits per call.

Signed-off-by: Rick Altherr <raltherr@google.com>
---

Changes in v2:
- Split API migration into separate patch

 drivers/char/hw_random/timeriomem-rng.c | 60 ++++++++++++++++-----------------
 1 file changed, 30 insertions(+), 30 deletions(-)

diff --git a/drivers/char/hw_random/timeriomem-rng.c b/drivers/char/hw_random/timeriomem-rng.c
index cf37db263ecd..17574452fd35 100644
--- a/drivers/char/hw_random/timeriomem-rng.c
+++ b/drivers/char/hw_random/timeriomem-rng.c
@@ -20,18 +20,16 @@
  * 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/hw_random.h>
 #include <linux/io.h>
+#include <linux/jiffies.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
 #include <linux/slab.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 {
 	void __iomem		*io_base;
@@ -45,32 +43,36 @@ struct timeriomem_rng_private_data {
 	struct hwrng		timeriomem_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);
+	struct timeriomem_rng_private_data *priv =
+		container_of(hwrng, struct timeriomem_rng_private_data,
+				timeriomem_rng_ops);
+	unsigned long cur;
+	s32 delay;
 
-	if (!wait || priv->present)
-		return priv->present;
+	/* The RNG provides 32-bit per read.  Ensure there is enough space. */
+	if (max < sizeof(u32))
+		return 0;
 
-	wait_for_completion(&priv->completion);
+	/*
+	 * 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;
 
-	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;
+	wait_for_completion(&priv->completion);
 
-	*data = readl(priv->io_base);
+	*(u32 *)data = readl(priv->io_base);
 
+	/*
+	 * Block any new callers until the RNG has had time to generate new
+	 * data.
+	 */
 	cur = jiffies;
 
 	delay = cur - priv->expires;
@@ -154,9 +156,7 @@ static int timeriomem_rng_probe(struct platform_device *pdev)
 	setup_timer(&priv->timer, timeriomem_rng_trigger, (unsigned long)priv);
 
 	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;
+	priv->timeriomem_rng_ops.read		= timeriomem_rng_read;
 
 	priv->io_base = devm_ioremap_resource(&pdev->dev, res);
 	if (IS_ERR(priv->io_base)) {
-- 
2.12.2.715.g7642488e1d-goog

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#1617423 — [PATCH v2 2/3] hw_random: timeriomem_rng: Shorten verbose type and variable names

No functional changes.

Signed-off-by: Rick Altherr <raltherr@google.com>
---

Changes in v2:
- Split type and variable renames into separate patch

 drivers/char/hw_random/timeriomem-rng.c | 27 +++++++++++++--------------
 1 file changed, 13 insertions(+), 14 deletions(-)

diff --git a/drivers/char/hw_random/timeriomem-rng.c b/drivers/char/hw_random/timeriomem-rng.c
index 17574452fd35..024bdff7999f 100644
--- a/drivers/char/hw_random/timeriomem-rng.c
+++ b/drivers/char/hw_random/timeriomem-rng.c
@@ -31,7 +31,7 @@
 #include <linux/timeriomem-rng.h>
 #include <linux/timer.h>
 
-struct timeriomem_rng_private_data {
+struct timeriomem_rng_private {
 	void __iomem		*io_base;
 	unsigned int		expires;
 	unsigned int		period;
@@ -40,15 +40,14 @@ struct timeriomem_rng_private_data {
 	struct timer_list	timer;
 	struct completion	completion;
 
-	struct hwrng		timeriomem_rng_ops;
+	struct hwrng		rng_ops;
 };
 
 static int timeriomem_rng_read(struct hwrng *hwrng, void *data,
 				size_t max, bool wait)
 {
-	struct timeriomem_rng_private_data *priv =
-		container_of(hwrng, struct timeriomem_rng_private_data,
-				timeriomem_rng_ops);
+	struct timeriomem_rng_private *priv =
+		container_of(hwrng, struct timeriomem_rng_private, rng_ops);
 	unsigned long cur;
 	s32 delay;
 
@@ -89,8 +88,8 @@ static int timeriomem_rng_read(struct hwrng *hwrng, void *data,
 
 static void timeriomem_rng_trigger(unsigned long data)
 {
-	struct timeriomem_rng_private_data *priv
-			= (struct timeriomem_rng_private_data *)data;
+	struct timeriomem_rng_private *priv
+			= (struct timeriomem_rng_private *)data;
 
 	priv->present = 1;
 	complete(&priv->completion);
@@ -99,7 +98,7 @@ static void timeriomem_rng_trigger(unsigned long data)
 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;
@@ -121,7 +120,7 @@ static int timeriomem_rng_probe(struct platform_device *pdev)
 
 	/* Allocate memory for the device structure (and zero it) */
 	priv = devm_kzalloc(&pdev->dev,
-			sizeof(struct timeriomem_rng_private_data), GFP_KERNEL);
+			sizeof(struct timeriomem_rng_private), GFP_KERNEL);
 	if (!priv)
 		return -ENOMEM;
 
@@ -155,8 +154,8 @@ static int timeriomem_rng_probe(struct platform_device *pdev)
 
 	setup_timer(&priv->timer, timeriomem_rng_trigger, (unsigned long)priv);
 
-	priv->timeriomem_rng_ops.name		= dev_name(&pdev->dev);
-	priv->timeriomem_rng_ops.read		= timeriomem_rng_read;
+	priv->rng_ops.name = dev_name(&pdev->dev);
+	priv->rng_ops.read = timeriomem_rng_read;
 
 	priv->io_base = devm_ioremap_resource(&pdev->dev, res);
 	if (IS_ERR(priv->io_base)) {
@@ -164,7 +163,7 @@ static int timeriomem_rng_probe(struct platform_device *pdev)
 		goto out_timer;
 	}
 
-	err = hwrng_register(&priv->timeriomem_rng_ops);
+	err = hwrng_register(&priv->rng_ops);
 	if (err) {
 		dev_err(&pdev->dev, "problem registering\n");
 		goto out_timer;
@@ -182,9 +181,9 @@ static int timeriomem_rng_probe(struct platform_device *pdev)
 
 static int timeriomem_rng_remove(struct platform_device *pdev)
 {
-	struct timeriomem_rng_private_data *priv = platform_get_drvdata(pdev);
+	struct timeriomem_rng_private *priv = platform_get_drvdata(pdev);
 
-	hwrng_unregister(&priv->timeriomem_rng_ops);
+	hwrng_unregister(&priv->rng_ops);
 
 	del_timer_sync(&priv->timer);
 
-- 
2.12.2.715.g7642488e1d-goog

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#1619841 — Re: [PATCH v2 0/3] hw_random: timeriomem_rng: Migrate to new API and improve performance

On Wed, Apr 05, 2017 at 04:20:57PM -0700, Rick Altherr wrote:
> AST2400 can generate 32-bits of random data every 1us.  Original driver
> was limited to one 32-bit read every jiffie due to deprecated API and use
> of timers.  Migrating to new hwrng API and switching to hrtimers
> improves read performance of /dev/hwrng to 13Mb/s.
> 
> Changes in v2:
> - Split API migration into separate patch
> - Split type and variable renames into separate patch
> - Split performance improvements into separate patch

All applied.  Thanks.
-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt

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