[PATCH v3 net-next] ravb: do not write 1 to reserved bits

From: Kazuya Mizuguchi <redacted>

EtherAVB hardware requires 0 to be written to status register bits in
order to clear them, however, care must be taken not to:

1. Clear other bits, by writing zero to them
2. Write one to reserved bits

This patch corrects the ravb driver with respect to the second point above.
This is done by defining reserved bit masks for the affected registers and,
after auditing the code, ensure all sites that may write a one to a
reserved bit use are suitably masked.

Signed-off-by: Kazuya Mizuguchi <redacted>
Signed-off-by: Simon Horman <redacted>
---
v3 [Simon Horman]
* Use GENMASK without cast nor the _ULL variant

v2 [Simon Horman]
* Cover ravb_timestamp_interrupt() by this change
* Use enum value rather than #define for reserved masks
* Reword changelog

v1 [Kazuya Mizuguchi]
---
 drivers/net/ethernet/renesas/ravb.h      |  5 +++++
 drivers/net/ethernet/renesas/ravb_main.c | 11 ++++++-----
 drivers/net/ethernet/renesas/ravb_ptp.c  |  2 +-
 3 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/drivers/net/ethernet/renesas/ravb.h b/drivers/net/ethernet/renesas/ravb.h
index 1470fc12282b..9b6bf557a2f5 100644
--- a/drivers/net/ethernet/renesas/ravb.h
+++ b/drivers/net/ethernet/renesas/ravb.h

@@ -428,6 +428,7 @@ enum EIS_BIT {
 	EIS_CULF1	= 0x00000080,
 	EIS_TFFF	= 0x00000100,
 	EIS_QFS		= 0x00010000,
+	EIS_RESERVED	= (GENMASK(31, 17) | GENMASK(15, 11)),
 };
 
 /* RIC0 */

@@ -472,6 +473,7 @@ enum RIS0_BIT {
 	RIS0_FRF15	= 0x00008000,
 	RIS0_FRF16	= 0x00010000,
 	RIS0_FRF17	= 0x00020000,
+	RIS0_RESERVED	= GENMASK(31, 18),
 };
 
 /* RIC1 */

@@ -528,6 +530,7 @@ enum RIS2_BIT {
 	RIS2_QFF16	= 0x00010000,
 	RIS2_QFF17	= 0x00020000,
 	RIS2_RFFF	= 0x80000000,
+	RIS2_RESERVED	= GENMASK(30, 18),
 };
 
 /* TIC */

@@ -544,6 +547,7 @@ enum TIS_BIT {
 	TIS_FTF1	= 0x00000002,	/* Undocumented? */
 	TIS_TFUF	= 0x00000100,
 	TIS_TFWF	= 0x00000200,
+	TIS_RESERVED	= (GENMASK(31, 20) | GENMASK(15, 12) | GENMASK(7, 4))
 };
 
 /* ISS */

@@ -617,6 +621,7 @@ enum GIC_BIT {
 enum GIS_BIT {
 	GIS_PTCF	= 0x00000001,	/* Undocumented? */
 	GIS_PTMF	= 0x00000004,
+	GIS_RESERVED	= GENMASK(15, 10),
 };
 
 /* GIE (R-Car Gen3 only) */

diff --git a/drivers/net/ethernet/renesas/ravb_main.c b/drivers/net/ethernet/renesas/ravb_main.c
index fb2a1125780d..cddb0c2856c8 100644
--- a/drivers/net/ethernet/renesas/ravb_main.c
+++ b/drivers/net/ethernet/renesas/ravb_main.c

@@ -739,10 +739,11 @@ static void ravb_error_interrupt(struct net_device *ndev)
 	u32 eis, ris2;
 
 	eis = ravb_read(ndev, EIS);
-	ravb_write(ndev, ~EIS_QFS, EIS);
+	ravb_write(ndev, ~(EIS_QFS | EIS_RESERVED), EIS);
 	if (eis & EIS_QFS) {
 		ris2 = ravb_read(ndev, RIS2);
-		ravb_write(ndev, ~(RIS2_QFF0 | RIS2_RFFF), RIS2);
+		ravb_write(ndev, ~(RIS2_QFF0 | RIS2_RFFF | RIS2_RESERVED),
+			   RIS2);
 
 		/* Receive Descriptor Empty int */
 		if (ris2 & RIS2_QFF0)

@@ -795,7 +796,7 @@ static bool ravb_timestamp_interrupt(struct net_device *ndev)
 	u32 tis = ravb_read(ndev, TIS);
 
 	if (tis & TIS_TFUF) {
-		ravb_write(ndev, ~TIS_TFUF, TIS);
+		ravb_write(ndev, ~(TIS_TFUF | TIS_RESERVED), TIS);
 		ravb_get_tx_tstamp(ndev);
 		return true;
 	}

@@ -930,7 +931,7 @@ static int ravb_poll(struct napi_struct *napi, int budget)
 		/* Processing RX Descriptor Ring */
 		if (ris0 & mask) {
 			/* Clear RX interrupt */
-			ravb_write(ndev, ~mask, RIS0);
+			ravb_write(ndev, ~(mask | RIS0_RESERVED), RIS0);
 			if (ravb_rx(ndev, &quota, q))
 				goto out;
 		}

@@ -938,7 +939,7 @@ static int ravb_poll(struct napi_struct *napi, int budget)
 		if (tis & mask) {
 			spin_lock_irqsave(&priv->lock, flags);
 			/* Clear TX interrupt */
-			ravb_write(ndev, ~mask, TIS);
+			ravb_write(ndev, ~(mask | TIS_RESERVED), TIS);
 			ravb_tx_free(ndev, q, true);
 			netif_wake_subqueue(ndev, q);
 			mmiowb();

diff --git a/drivers/net/ethernet/renesas/ravb_ptp.c b/drivers/net/ethernet/renesas/ravb_ptp.c
index 0721b5c35d91..dce2a40a31e3 100644
--- a/drivers/net/ethernet/renesas/ravb_ptp.c
+++ b/drivers/net/ethernet/renesas/ravb_ptp.c

@@ -315,7 +315,7 @@ void ravb_ptp_interrupt(struct net_device *ndev)
 		}
 	}
 
-	ravb_write(ndev, ~gis, GIS);
+	ravb_write(ndev, ~(gis | GIS_RESERVED), GIS);
 }
 
 void ravb_ptp_init(struct net_device *ndev, struct platform_device *pdev)

-- 
2.11.0

On 09/18/2018 01:22 PM, Simon Horman wrote:

From: Kazuya Mizuguchi <redacted>

EtherAVB hardware requires 0 to be written to status register bits in
order to clear them, however, care must be taken not to:

1. Clear other bits, by writing zero to them
2. Write one to reserved bits

This patch corrects the ravb driver with respect to the second point above.
This is done by defining reserved bit masks for the affected registers and,
after auditing the code, ensure all sites that may write a one to a
reserved bit use are suitably masked.

Signed-off-by: Kazuya Mizuguchi <redacted>
Signed-off-by: Simon Horman <redacted>

[...]

Reviewed-by: Sergei Shtylyov <redacted>

   Well, I'm not a big fan of BIT() and GENMASK() -- they still lack a macro
to #define a bit/field value. But if you prefer to use them, OK, let's be so...

[...]

MBR, Sergei

On 09/18/2018 01:22 PM, Simon Horman wrote:

From: Kazuya Mizuguchi <redacted>

EtherAVB hardware requires 0 to be written to status register bits in
order to clear them, however, care must be taken not to:

1. Clear other bits, by writing zero to them
2. Write one to reserved bits

This patch corrects the ravb driver with respect to the second point above.
This is done by defining reserved bit masks for the affected registers and,
after auditing the code, ensure all sites that may write a one to a
reserved bit use are suitably masked.

Signed-off-by: Kazuya Mizuguchi <redacted>
Signed-off-by: Simon Horman <redacted>

   BTW, perhaps this should be merged into net.git instead? DaveM, your call? :-)

MBR, Sergei

From: Simon Horman <redacted>
Date: Tue, 18 Sep 2018 12:22:26 +0200

From: Kazuya Mizuguchi <redacted>

EtherAVB hardware requires 0 to be written to status register bits in
order to clear them, however, care must be taken not to:

1. Clear other bits, by writing zero to them
2. Write one to reserved bits

This patch corrects the ravb driver with respect to the second point above.
This is done by defining reserved bit masks for the affected registers and,
after auditing the code, ensure all sites that may write a one to a
reserved bit use are suitably masked.

Signed-off-by: Kazuya Mizuguchi <redacted>
Signed-off-by: Simon Horman <redacted>

I've decided to apply this to 'net', let me know if this is a problem.

On Tue, Sep 18, 2018 at 08:10:26PM -0700, David Miller wrote:

From: Simon Horman <redacted>
Date: Tue, 18 Sep 2018 12:22:26 +0200

quoted

From: Kazuya Mizuguchi <redacted>

EtherAVB hardware requires 0 to be written to status register bits in
order to clear them, however, care must be taken not to:

1. Clear other bits, by writing zero to them
2. Write one to reserved bits

This patch corrects the ravb driver with respect to the second point above.
This is done by defining reserved bit masks for the affected registers and,
after auditing the code, ensure all sites that may write a one to a
reserved bit use are suitably masked.

Signed-off-by: Kazuya Mizuguchi <redacted>
Signed-off-by: Simon Horman <redacted>

I've decided to apply this to 'net', let me know if this is a problem.

Thanks Dave, 'net' is fine by me.

Hi Sergei,

On Tue, Sep 18, 2018 at 6:55 PM Sergei Shtylyov
[off-list ref] wrote:

On 09/18/2018 01:22 PM, Simon Horman wrote:

quoted

From: Kazuya Mizuguchi <redacted>
EtherAVB hardware requires 0 to be written to status register bits in
order to clear them, however, care must be taken not to:

1. Clear other bits, by writing zero to them
2. Write one to reserved bits

This patch corrects the ravb driver with respect to the second point above.
This is done by defining reserved bit masks for the affected registers and,
after auditing the code, ensure all sites that may write a one to a
reserved bit use are suitably masked.

Signed-off-by: Kazuya Mizuguchi <redacted>
Signed-off-by: Simon Horman <redacted>

[...]

Reviewed-by: Sergei Shtylyov <redacted>

quoted

diff --git a/drivers/net/ethernet/renesas/ravb.h b/drivers/net/ethernet/renesas/ravb.h
index 1470fc12282b..9b6bf557a2f5 100644
--- a/drivers/net/ethernet/renesas/ravb.h
+++ b/drivers/net/ethernet/renesas/ravb.h

@@ -428,6 +428,7 @@ enum EIS_BIT {
      EIS_CULF1       = 0x00000080,
      EIS_TFFF        = 0x00000100,
      EIS_QFS         = 0x00010000,
+     EIS_RESERVED    = (GENMASK(31, 17) | GENMASK(15, 11)),

   Well, I'm not a big fan of BIT() and GENMASK() -- they still lack a macro
to #define a bit/field value. But if you prefer to use them, OK, let's be so...

FIELD_PREP()?

Perhaps the other bit definitions should be converted to BIT()?
That way it becomes much easier to match valid EIS_* bits with EIS_RESERVED.

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

On Tue, Oct 09, 2018 at 11:28:40AM +0200, Geert Uytterhoeven wrote:

Hi Sergei,

On Tue, Sep 18, 2018 at 6:55 PM Sergei Shtylyov
[off-list ref] wrote:

quoted

On 09/18/2018 01:22 PM, Simon Horman wrote:

quoted

From: Kazuya Mizuguchi <redacted>
EtherAVB hardware requires 0 to be written to status register bits in
order to clear them, however, care must be taken not to:

1. Clear other bits, by writing zero to them
2. Write one to reserved bits

This patch corrects the ravb driver with respect to the second point above.
This is done by defining reserved bit masks for the affected registers and,
after auditing the code, ensure all sites that may write a one to a
reserved bit use are suitably masked.

Signed-off-by: Kazuya Mizuguchi <redacted>
Signed-off-by: Simon Horman <redacted>

[...]

Reviewed-by: Sergei Shtylyov <redacted>

quoted

diff --git a/drivers/net/ethernet/renesas/ravb.h b/drivers/net/ethernet/renesas/ravb.h
index 1470fc12282b..9b6bf557a2f5 100644
--- a/drivers/net/ethernet/renesas/ravb.h
+++ b/drivers/net/ethernet/renesas/ravb.h

@@ -428,6 +428,7 @@ enum EIS_BIT {
      EIS_CULF1       = 0x00000080,
      EIS_TFFF        = 0x00000100,
      EIS_QFS         = 0x00010000,
+     EIS_RESERVED    = (GENMASK(31, 17) | GENMASK(15, 11)),

   Well, I'm not a big fan of BIT() and GENMASK() -- they still lack a macro
to #define a bit/field value. But if you prefer to use them, OK, let's be so...

FIELD_PREP()?

Perhaps the other bit definitions should be converted to BIT()?
That way it becomes much easier to match valid EIS_* bits with EIS_RESERVED.

+1