[PATCH v2 0/5] hwrng: amd: rework of the amd hwrng driver

[PATCH v2 0/5] hwrng: amd: rework of the amd hwrng driver

[LABBE Corentin]

Changes since v1:
 - Keep the hwrng name as "amd"

LABBE Corentin (5):
  hwrng: amd: Fix style problem with blank line
  hwrng: amd: use the BIT macro
  hwrng: amd: Be consitent with the driver name
  hwrng: amd: Remove asm/io.h
  hwrng: amd: Rework of the amd768-hwrng driver

 drivers/char/hw_random/amd-rng.c | 173 ++++++++++++++++++++++++---------------
 1 file changed, 107 insertions(+), 66 deletions(-)

-- 
2.7.3

[PATCH v2 1/5] hwrng: amd: Fix style problem with blank line

[LABBE Corentin]

Some blank line are unncessary, and one is missing after declaration.
This patch fix thoses style problems.

Signed-off-by: LABBE Corentin <clabbe.montjoie@gmail.com>
---
 drivers/char/hw_random/amd-rng.c | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/drivers/char/hw_random/amd-rng.c b/drivers/char/hw_random/amd-rng.c
index 48f6a83..45b7965 100644
--- a/drivers/char/hw_random/amd-rng.c
+++ b/drivers/char/hw_random/amd-rng.c
@@ -31,10 +31,8 @@
 #include <linux/delay.h>
 #include <asm/io.h>
 
-
 #define PFX	KBUILD_MODNAME ": "
 
-
 /*
  * Data for PCI driver interface
  *
@@ -52,7 +50,6 @@ MODULE_DEVICE_TABLE(pci, pci_tbl);
 
 static struct pci_dev *amd_pdev;
 
-
 static int amd_rng_data_present(struct hwrng *rng, int wait)
 {
 	u32 pmbase = (u32)rng->priv;
@@ -100,7 +97,6 @@ static void amd_rng_cleanup(struct hwrng *rng)
 	pci_write_config_byte(amd_pdev, 0x40, rnen);
 }
 
-
 static struct hwrng amd_rng = {
 	.name		= "amd",
 	.init		= amd_rng_init,
@@ -109,7 +105,6 @@ static struct hwrng amd_rng = {
 	.data_read	= amd_rng_data_read,
 };
 
-
 static int __init mod_init(void)
 {
 	int err = -ENODEV;
@@ -157,6 +152,7 @@ out:
 static void __exit mod_exit(void)
 {
 	u32 pmbase = (unsigned long)amd_rng.priv;
+
 	release_region(pmbase + 0xF0, 8);
 	hwrng_unregister(&amd_rng);
 }
-- 
2.7.3

[PATCH v2 2/5] hwrng: amd: use the BIT macro

[LABBE Corentin]

This patch add usage of the BIT() macro

Signed-off-by: LABBE Corentin <clabbe.montjoie@gmail.com>
---
 drivers/char/hw_random/amd-rng.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/char/hw_random/amd-rng.c b/drivers/char/hw_random/amd-rng.c
index 45b7965..d0042f5 100644
--- a/drivers/char/hw_random/amd-rng.c
+++ b/drivers/char/hw_random/amd-rng.c
@@ -78,11 +78,11 @@ static int amd_rng_init(struct hwrng *rng)
 	u8 rnen;
 
 	pci_read_config_byte(amd_pdev, 0x40, &rnen);
-	rnen |= (1 << 7);	/* RNG on */
+	rnen |= BIT(7);	/* RNG on */
 	pci_write_config_byte(amd_pdev, 0x40, rnen);
 
 	pci_read_config_byte(amd_pdev, 0x41, &rnen);
-	rnen |= (1 << 7);	/* PMIO enable */
+	rnen |= BIT(7);	/* PMIO enable */
 	pci_write_config_byte(amd_pdev, 0x41, rnen);
 
 	return 0;
@@ -93,7 +93,7 @@ static void amd_rng_cleanup(struct hwrng *rng)
 	u8 rnen;
 
 	pci_read_config_byte(amd_pdev, 0x40, &rnen);
-	rnen &= ~(1 << 7);	/* RNG off */
+	rnen &= ~BIT(7);	/* RNG off */
 	pci_write_config_byte(amd_pdev, 0x40, rnen);
 }
 
-- 
2.7.3

[PATCH v2 3/5] hwrng: amd: Be consitent with the driver name

[LABBE Corentin]

The driver name is displayed each time differently.
This patch make use of the same name everywhere.

Signed-off-by: LABBE Corentin <clabbe.montjoie@gmail.com>
---
 drivers/char/hw_random/amd-rng.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/drivers/char/hw_random/amd-rng.c b/drivers/char/hw_random/amd-rng.c
index d0042f5..93157af 100644
--- a/drivers/char/hw_random/amd-rng.c
+++ b/drivers/char/hw_random/amd-rng.c
@@ -31,7 +31,7 @@
 #include <linux/delay.h>
 #include <asm/io.h>
 
-#define PFX	KBUILD_MODNAME ": "
+#define DRV_NAME "AMD768-HWRNG"
 
 /*
  * Data for PCI driver interface
@@ -128,8 +128,8 @@ found:
 	pmbase &= 0x0000FF00;
 	if (pmbase == 0)
 		goto out;
-	if (!request_region(pmbase + 0xF0, 8, "AMD HWRNG")) {
-		dev_err(&pdev->dev, "AMD HWRNG region 0x%x already in use!\n",
+	if (!request_region(pmbase + 0xF0, 8, DRV_NAME)) {
+		dev_err(&pdev->dev, DRV_NAME " region 0x%x already in use!\n",
 			pmbase + 0xF0);
 		err = -EBUSY;
 		goto out;
@@ -137,11 +137,10 @@ found:
 	amd_rng.priv = (unsigned long)pmbase;
 	amd_pdev = pdev;
 
-	pr_info("AMD768 RNG detected\n");
+	pr_info(DRV_NAME " detected\n");
 	err = hwrng_register(&amd_rng);
 	if (err) {
-		pr_err(PFX "RNG registering failed (%d)\n",
-		       err);
+		pr_err(DRV_NAME " registering failed (%d)\n", err);
 		release_region(pmbase + 0xF0, 8);
 		goto out;
 	}
-- 
2.7.3

[PATCH v2 4/5] hwrng: amd: Remove asm/io.h

[LABBE Corentin]

checkpatch complains about <asm/io.h> used instead of linux/io.h.
In fact it is not needed.
This patch remove it, and in the process, alphabetize the other headers.

Signed-off-by: LABBE Corentin <clabbe.montjoie@gmail.com>
---
 drivers/char/hw_random/amd-rng.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/drivers/char/hw_random/amd-rng.c b/drivers/char/hw_random/amd-rng.c
index 93157af..de82fe3 100644
--- a/drivers/char/hw_random/amd-rng.c
+++ b/drivers/char/hw_random/amd-rng.c
@@ -24,12 +24,11 @@
  * warranty of any kind, whether express or implied.
  */
 
-#include <linux/module.h>
+#include <linux/delay.h>
+#include <linux/hw_random.h>
 #include <linux/kernel.h>
+#include <linux/module.h>
 #include <linux/pci.h>
-#include <linux/hw_random.h>
-#include <linux/delay.h>
-#include <asm/io.h>
 
 #define DRV_NAME "AMD768-HWRNG"
 
-- 
2.7.3

[PATCH v2 5/5] hwrng: amd: Rework of the amd768-hwrng driver

[LABBE Corentin]

This patch convert the hwrng interface used by amd768-rng to its new API
by replacing data_read()/data_present() by read().

Furthermore, Instead of having two global variable, it's better to use a
private struct. This will permit to remove amd_pdev variable.

Finally, Instead of accessing hw directly via pmbase, it's better to
access after ioport_map() via ioread32/iowrite32.

Signed-off-by: LABBE Corentin <clabbe.montjoie@gmail.com>
---
 drivers/char/hw_random/amd-rng.c | 151 +++++++++++++++++++++++++--------------
 1 file changed, 99 insertions(+), 52 deletions(-)

diff --git a/drivers/char/hw_random/amd-rng.c b/drivers/char/hw_random/amd-rng.c
index de82fe3..785bc3e 100644
--- a/drivers/char/hw_random/amd-rng.c
+++ b/drivers/char/hw_random/amd-rng.c
@@ -32,6 +32,14 @@
 
 #define DRV_NAME "AMD768-HWRNG"
 
+#define GEN_CFG_REG1	0x40
+#define GEN_CFG_REG2	0x41
+#define SMIO_SPACEPTR	0x58
+#define RNGDATA		0x00
+#define RNGDONE		0x04
+#define PMBASE_OFFSET	0xF0
+#define PMBASE_SIZE	8
+
 /*
  * Data for PCI driver interface
  *
@@ -39,6 +47,7 @@
  * PCI ids via MODULE_DEVICE_TABLE.  We do not actually
  * register a pci_driver, because someone else might one day
  * want to register another driver on the same PCI id.
+ * Like i2c-amd756
  */
 static const struct pci_device_id pci_tbl[] = {
 	{ PCI_VDEVICE(AMD, 0x7443), 0, },
@@ -47,112 +56,150 @@ static const struct pci_device_id pci_tbl[] = {
 };
 MODULE_DEVICE_TABLE(pci, pci_tbl);
 
-static struct pci_dev *amd_pdev;
+struct amd768_priv {
+	void __iomem *iobase;
+	struct pci_dev *pcidev;
+	u32 pmbase;
+};
 
-static int amd_rng_data_present(struct hwrng *rng, int wait)
+static int amd_rng_read(struct hwrng *rng, void *buf, size_t max, bool wait)
 {
-	u32 pmbase = (u32)rng->priv;
-	int data, i;
-
-	for (i = 0; i < 20; i++) {
-		data = !!(inl(pmbase + 0xF4) & 1);
-		if (data || !wait)
-			break;
-		udelay(10);
+	u32 *data = buf;
+	struct amd768_priv *priv = (struct amd768_priv *)rng->priv;
+	size_t read = 0;
+	/* We will wait at maximum one time per read */
+	int timeout = max / 4 + 1;
+
+	/*
+	 * RNG data is available when RNGDONE is set to 1
+	 * New random numbers are generated approximately 128 microseconds
+	 * after RNGDATA is read
+	 */
+	while (read < max) {
+		if (ioread32(priv->iobase + RNGDONE) == 0) {
+			if (wait) {
+				/* Delay given by datasheet */
+				usleep_range(128, 196);
+				if (timeout-- == 0)
+					return read;
+			} else {
+				return 0;
+			}
+		} else {
+			*data = ioread32(priv->iobase + RNGDATA);
+			data++;
+			read += 4;
+		}
 	}
-	return data;
-}
-
-static int amd_rng_data_read(struct hwrng *rng, u32 *data)
-{
-	u32 pmbase = (u32)rng->priv;
 
-	*data = inl(pmbase + 0xF0);
-
-	return 4;
+	return read;
 }
 
 static int amd_rng_init(struct hwrng *rng)
 {
 	u8 rnen;
+	struct amd768_priv *priv = (struct amd768_priv *)rng->priv;
 
-	pci_read_config_byte(amd_pdev, 0x40, &rnen);
+	pci_read_config_byte(priv->pcidev, GEN_CFG_REG1, &rnen);
 	rnen |= BIT(7);	/* RNG on */
-	pci_write_config_byte(amd_pdev, 0x40, rnen);
+	pci_write_config_byte(priv->pcidev, GEN_CFG_REG1, rnen);
 
-	pci_read_config_byte(amd_pdev, 0x41, &rnen);
+	pci_read_config_byte(priv->pcidev, GEN_CFG_REG2, &rnen);
 	rnen |= BIT(7);	/* PMIO enable */
-	pci_write_config_byte(amd_pdev, 0x41, rnen);
-
+	pci_write_config_byte(priv->pcidev, GEN_CFG_REG2, rnen);
 	return 0;
 }
 
 static void amd_rng_cleanup(struct hwrng *rng)
 {
 	u8 rnen;
+	struct amd768_priv *priv = (struct amd768_priv *)rng->priv;
 
-	pci_read_config_byte(amd_pdev, 0x40, &rnen);
+	pci_read_config_byte(priv->pcidev, GEN_CFG_REG1, &rnen);
 	rnen &= ~BIT(7);	/* RNG off */
-	pci_write_config_byte(amd_pdev, 0x40, rnen);
+	pci_write_config_byte(priv->pcidev, GEN_CFG_REG1, rnen);
 }
 
 static struct hwrng amd_rng = {
 	.name		= "amd",
+	.read		= amd_rng_read,
 	.init		= amd_rng_init,
 	.cleanup	= amd_rng_cleanup,
-	.data_present	= amd_rng_data_present,
-	.data_read	= amd_rng_data_read,
 };
 
-static int __init mod_init(void)
+static int mod_init(void)
 {
-	int err = -ENODEV;
+	int err;
 	struct pci_dev *pdev = NULL;
 	const struct pci_device_id *ent;
 	u32 pmbase;
+	struct amd768_priv *priv;
 
 	for_each_pci_dev(pdev) {
 		ent = pci_match_id(pci_tbl, pdev);
 		if (ent)
 			goto found;
 	}
-	/* Device not found. */
-	goto out;
-
+	return -ENODEV;
 found:
-	err = pci_read_config_dword(pdev, 0x58, &pmbase);
+
+	err = pci_read_config_dword(pdev, SMIO_SPACEPTR, &pmbase);
 	if (err)
-		goto out;
-	err = -EIO;
+		return err;
+
 	pmbase &= 0x0000FF00;
-	if (pmbase == 0)
-		goto out;
-	if (!request_region(pmbase + 0xF0, 8, DRV_NAME)) {
-		dev_err(&pdev->dev, DRV_NAME " region 0x%x already in use!\n",
-			pmbase + 0xF0);
-		err = -EBUSY;
-		goto out;
+
+	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	if (!request_region(pmbase + PMBASE_OFFSET, PMBASE_SIZE, DRV_NAME)) {
+		pr_err(DRV_NAME "region 0x%x already in use!\n", pmbase);
+		goto err_pmbase;
+	}
+
+	priv->iobase = ioport_map(pmbase + PMBASE_OFFSET, PMBASE_SIZE);
+	if (!priv->iobase) {
+		pr_err(DRV_NAME "Cannot map ioport\n");
+		err = -EINVAL;
+		goto err_iomap;
 	}
-	amd_rng.priv = (unsigned long)pmbase;
-	amd_pdev = pdev;
+
+	amd_rng.priv = (unsigned long)priv;
+	priv->pmbase = pmbase;
+	priv->pcidev = pdev;
 
 	pr_info(DRV_NAME " detected\n");
+
 	err = hwrng_register(&amd_rng);
 	if (err) {
-		pr_err(DRV_NAME " registering failed (%d)\n", err);
-		release_region(pmbase + 0xF0, 8);
-		goto out;
+		pr_err(DRV_NAME "Cannot register HWRNG %d\n", err);
+		goto err_hwrng;
 	}
-out:
+	return 0;
+
+err_hwrng:
+	ioport_unmap(priv->iobase);
+err_iomap:
+	release_region(pmbase + PMBASE_OFFSET, PMBASE_SIZE);
+err_pmbase:
+	kfree(priv);
 	return err;
 }
 
-static void __exit mod_exit(void)
+static void mod_exit(void)
 {
-	u32 pmbase = (unsigned long)amd_rng.priv;
+	struct amd768_priv *priv;
+
+	priv = (struct amd768_priv *)amd_rng.priv;
 
-	release_region(pmbase + 0xF0, 8);
 	hwrng_unregister(&amd_rng);
+
+	ioport_unmap(priv->iobase);
+
+	release_region(priv->pmbase + PMBASE_OFFSET, PMBASE_SIZE);
+
+	kfree(priv);
 }
 
 module_init(mod_init);
-- 
2.7.3

Re: [PATCH v2 5/5] hwrng: amd: Rework of the amd768-hwrng driver

[Jason Cooper]

Hi Corentin,

On Thu, Aug 25, 2016 at 02:16:35PM +0200, LABBE Corentin wrote:
> This patch convert the hwrng interface used by amd768-rng to its new API
> by replacing data_read()/data_present() by read().
> 
> Furthermore, Instead of having two global variable, it's better to use a
> private struct. This will permit to remove amd_pdev variable.
> 
> Finally, Instead of accessing hw directly via pmbase, it's better to
> access after ioport_map() via ioread32/iowrite32.

I was going to recommend a better $subject line, but now I see why it's
vague. :(  I would recommend breaking this patch up into three:

  hwrng: amd - Access hardware via ioread32/iowrite32
  hwrng: amd - Replace global variable with private struct
  hwrng: amd - Convert to new hwrng read() API

thx,

Jason.

Re: [PATCH v2 5/5] hwrng: amd: Rework of the amd768-hwrng driver

[LABBE Corentin]

On Thu, Aug 25, 2016 at 02:56:38PM +0000, Jason Cooper wrote:
> Hi Corentin,
> 
> On Thu, Aug 25, 2016 at 02:16:35PM +0200, LABBE Corentin wrote:
> > This patch convert the hwrng interface used by amd768-rng to its new API
> > by replacing data_read()/data_present() by read().
> > 
> > Furthermore, Instead of having two global variable, it's better to use a
> > private struct. This will permit to remove amd_pdev variable.
> > 
> > Finally, Instead of accessing hw directly via pmbase, it's better to
> > access after ioport_map() via ioread32/iowrite32.
> 
> I was going to recommend a better $subject line, but now I see why it's
> vague. :(  I would recommend breaking this patch up into three:
> 
>   hwrng: amd - Access hardware via ioread32/iowrite32
>   hwrng: amd - Replace global variable with private struct
>   hwrng: amd - Convert to new hwrng read() API
> 

That was my first idea, but believed that it wasnt worth it.

Anyway I will do it.

Regards
LABBE Corentin

Re: [PATCH v2 5/5] hwrng: amd: Rework of the amd768-hwrng driver

[Jason Cooper]

Hi Corentin,

On Fri, Aug 26, 2016 at 10:38:02AM +0200, LABBE Corentin wrote:
> On Thu, Aug 25, 2016 at 02:56:38PM +0000, Jason Cooper wrote:
> > On Thu, Aug 25, 2016 at 02:16:35PM +0200, LABBE Corentin wrote:
> > > This patch convert the hwrng interface used by amd768-rng to its new API
> > > by replacing data_read()/data_present() by read().
> > > 
> > > Furthermore, Instead of having two global variable, it's better to use a
> > > private struct. This will permit to remove amd_pdev variable.
> > > 
> > > Finally, Instead of accessing hw directly via pmbase, it's better to
> > > access after ioport_map() via ioread32/iowrite32.
> > 
> > I was going to recommend a better $subject line, but now I see why it's
> > vague. :(  I would recommend breaking this patch up into three:
> > 
> >   hwrng: amd - Access hardware via ioread32/iowrite32
> >   hwrng: amd - Replace global variable with private struct
> >   hwrng: amd - Convert to new hwrng read() API
> > 
> 
> That was my first idea, but believed that it wasnt worth it.

When working with crypto/rng code, I'm a firm believer in moving
cautiously and deliberately. :-)

> Anyway I will do it.

Thanks!

thx,

Jason.