[PATCH 1/2] can: sja1000: add documentation for Technologic Systems version

[PATCH 1/2] can: sja1000: add documentation for Technologic Systems version

[Damien Riegel]

This commit adds documentation for the Technologic Systems version of
SJA1000. The difference with the NXP version is in the way the registers
are accessed.

Signed-off-by: Damien Riegel <damien.riegel@savoirfairelinux.com>
---
 Documentation/devicetree/bindings/net/can/sja1000.txt | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/Documentation/devicetree/bindings/net/can/sja1000.txt b/Documentation/devicetree/bindings/net/can/sja1000.txt
index b4a6d53..7a158d5 100644
--- a/Documentation/devicetree/bindings/net/can/sja1000.txt
+++ b/Documentation/devicetree/bindings/net/can/sja1000.txt
@@ -2,7 +2,7 @@ Memory mapped SJA1000 CAN controller from NXP (formerly Philips)
 
 Required properties:
 
-- compatible : should be "nxp,sja1000".
+- compatible : should be one of "nxp,sja1000", "technologic,sja1000".
 
 - reg : should specify the chip select, address offset and size required
 	to map the registers of the SJA1000. The size is usually 0x80.
@@ -14,6 +14,7 @@ Optional properties:
 
 - reg-io-width : Specify the size (in bytes) of the IO accesses that
 	should be performed on the device.  Valid value is 1, 2 or 4.
+	Must be set to 2 for technologic version.
 	Default to 1 (8 bits).
 
 - nxp,external-clock-frequency : Frequency of the external oscillator
-- 
2.5.0

[PATCH 2/2] can: sja1000: of: add compatibility with Technologic Systems version

[Damien Riegel]

Technologic Systems provides an IP compatible with the SJA1000,
instantiated in an FPGA. Because of some bus widths issue, access to
registers is made through a "window" that works like this:

    base + 0x0: address to read/write
    base + 0x2: 8-bit register value

This commit adds a new compatible device, "technologic,sja1000", with
read and write functions using the window mechanism.

Signed-off-by: Damien Riegel <damien.riegel@savoirfairelinux.com>
---
 drivers/net/can/sja1000/sja1000_platform.c | 30 ++++++++++++++++++++++++++++--
 1 file changed, 28 insertions(+), 2 deletions(-)

diff --git a/drivers/net/can/sja1000/sja1000_platform.c b/drivers/net/can/sja1000/sja1000_platform.c
index 0552ed4..6cbf251 100644
--- a/drivers/net/can/sja1000/sja1000_platform.c
+++ b/drivers/net/can/sja1000/sja1000_platform.c
@@ -70,6 +70,18 @@ static void sp_write_reg32(const struct sja1000_priv *priv, int reg, u8 val)
 	iowrite8(val, priv->reg_base + reg * 4);
 }
 
+static u8 ts4800_read_reg16(const struct sja1000_priv *priv, int reg)
+{
+	sp_write_reg16(priv, 0,  reg);
+	return sp_read_reg16(priv, 2);
+}
+
+static void ts4800_write_reg16(const struct sja1000_priv *priv, int reg, u8 val)
+{
+	sp_write_reg16(priv, 0, reg);
+	sp_write_reg16(priv, 2, val);
+}
+
 static void sp_populate(struct sja1000_priv *priv,
 			struct sja1000_platform_data *pdata,
 			unsigned long resource_mem_flags)
@@ -98,21 +110,34 @@ static void sp_populate(struct sja1000_priv *priv,
 
 static void sp_populate_of(struct sja1000_priv *priv, struct device_node *of)
 {
+	int is_technologic;
 	int err;
 	u32 prop;
 
+	is_technologic = of_device_is_compatible(of, "technologic,sja1000");
+
 	err = of_property_read_u32(of, "reg-io-width", &prop);
 	if (err)
 		prop = 1; /* 8 bit is default */
 
+	if (is_technologic && prop != 2) {
+		netdev_warn(priv->dev, "forcing reg-io-width to 2\n");
+		prop = 2;
+	}
+
 	switch (prop) {
 	case 4:
 		priv->read_reg = sp_read_reg32;
 		priv->write_reg = sp_write_reg32;
 		break;
 	case 2:
-		priv->read_reg = sp_read_reg16;
-		priv->write_reg = sp_write_reg16;
+		if (is_technologic) {
+			priv->read_reg = ts4800_read_reg16;
+			priv->write_reg = ts4800_write_reg16;
+		} else {
+			priv->read_reg = sp_read_reg16;
+			priv->write_reg = sp_write_reg16;
+		}
 		break;
 	case 1:	/* fallthrough */
 	default:
@@ -244,6 +269,7 @@ static int sp_remove(struct platform_device *pdev)
 
 static const struct of_device_id sp_of_table[] = {
 	{.compatible = "nxp,sja1000"},
+	{.compatible = "technologic,sja1000"},
 	{},
 };
 MODULE_DEVICE_TABLE(of, sp_of_table);
-- 
2.5.0

Re: [PATCH 2/2] can: sja1000: of: add compatibility with Technologic Systems version

[Marc Kleine-Budde]

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On 12/18/2015 09:17 PM, Damien Riegel wrote:
> Technologic Systems provides an IP compatible with the SJA1000,
> instantiated in an FPGA. Because of some bus widths issue, access to
> registers is made through a "window" that works like this:
> 
>     base + 0x0: address to read/write
>     base + 0x2: 8-bit register value
> 
> This commit adds a new compatible device, "technologic,sja1000", with
> read and write functions using the window mechanism.
> 
> Signed-off-by: Damien Riegel <damien.riegel@savoirfairelinux.com>
> ---
>  drivers/net/can/sja1000/sja1000_platform.c | 30 ++++++++++++++++++++++++++++--
>  1 file changed, 28 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/can/sja1000/sja1000_platform.c b/drivers/net/can/sja1000/sja1000_platform.c
> index 0552ed4..6cbf251 100644
> --- a/drivers/net/can/sja1000/sja1000_platform.c
> +++ b/drivers/net/can/sja1000/sja1000_platform.c
> @@ -70,6 +70,18 @@ static void sp_write_reg32(const struct sja1000_priv *priv, int reg, u8 val)
>  	iowrite8(val, priv->reg_base + reg * 4);
>  }
>  
> +static u8 ts4800_read_reg16(const struct sja1000_priv *priv, int reg)
> +{
> +	sp_write_reg16(priv, 0,  reg);
> +	return sp_read_reg16(priv, 2);

This is racy, please add a spinlock.

> +}
> +
> +static void ts4800_write_reg16(const struct sja1000_priv *priv, int reg, u8 val)
> +{
> +	sp_write_reg16(priv, 0, reg);
> +	sp_write_reg16(priv, 2, val);

This is racy, too.

Have a look at https://marc.info/?l=linux-can&m=137149497403825&w=2

Marc

> +}
> +
>  static void sp_populate(struct sja1000_priv *priv,
>  			struct sja1000_platform_data *pdata,
>  			unsigned long resource_mem_flags)
> @@ -98,21 +110,34 @@ static void sp_populate(struct sja1000_priv *priv,
>  
>  static void sp_populate_of(struct sja1000_priv *priv, struct device_node *of)
>  {
> +	int is_technologic;
>  	int err;
>  	u32 prop;
>  
> +	is_technologic = of_device_is_compatible(of, "technologic,sja1000");
> +
>  	err = of_property_read_u32(of, "reg-io-width", &prop);
>  	if (err)
>  		prop = 1; /* 8 bit is default */
>  
> +	if (is_technologic && prop != 2) {
> +		netdev_warn(priv->dev, "forcing reg-io-width to 2\n");
> +		prop = 2;
> +	}
> +
>  	switch (prop) {
>  	case 4:
>  		priv->read_reg = sp_read_reg32;
>  		priv->write_reg = sp_write_reg32;
>  		break;
>  	case 2:
> -		priv->read_reg = sp_read_reg16;
> -		priv->write_reg = sp_write_reg16;
> +		if (is_technologic) {
> +			priv->read_reg = ts4800_read_reg16;
> +			priv->write_reg = ts4800_write_reg16;
> +		} else {
> +			priv->read_reg = sp_read_reg16;
> +			priv->write_reg = sp_write_reg16;
> +		}
>  		break;
>  	case 1:	/* fallthrough */
>  	default:
> @@ -244,6 +269,7 @@ static int sp_remove(struct platform_device *pdev)
>  
>  static const struct of_device_id sp_of_table[] = {
>  	{.compatible = "nxp,sja1000"},
> +	{.compatible = "technologic,sja1000"},
>  	{},
>  };
>  MODULE_DEVICE_TABLE(of, sp_of_table);
> 


-- 
Pengutronix e.K.                  | Marc Kleine-Budde           |
Industrial Linux Solutions        | Phone: +49-231-2826-924     |
Vertretung West/Dortmund          | Fax:   +49-5121-206917-5555 |
Amtsgericht Hildesheim, HRA 2686  | http://www.pengutronix.de   |


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Re: [PATCH 2/2] can: sja1000: of: add compatibility with Technologic Systems version

[Damien Riegel]

On Fri, Dec 18, 2015 at 09:41:47PM +0100, Marc Kleine-Budde wrote:
> On 12/18/2015 09:17 PM, Damien Riegel wrote:
> > Technologic Systems provides an IP compatible with the SJA1000,
> > instantiated in an FPGA. Because of some bus widths issue, access to
> > registers is made through a "window" that works like this:
> > 
> >     base + 0x0: address to read/write
> >     base + 0x2: 8-bit register value
> > 
> > This commit adds a new compatible device, "technologic,sja1000", with
> > read and write functions using the window mechanism.
> > 
> > Signed-off-by: Damien Riegel <damien.riegel@savoirfairelinux.com>
> > ---
> >  drivers/net/can/sja1000/sja1000_platform.c | 30 ++++++++++++++++++++++++++++--
> >  1 file changed, 28 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/net/can/sja1000/sja1000_platform.c b/drivers/net/can/sja1000/sja1000_platform.c
> > index 0552ed4..6cbf251 100644
> > --- a/drivers/net/can/sja1000/sja1000_platform.c
> > +++ b/drivers/net/can/sja1000/sja1000_platform.c
> > @@ -70,6 +70,18 @@ static void sp_write_reg32(const struct sja1000_priv *priv, int reg, u8 val)
> >  	iowrite8(val, priv->reg_base + reg * 4);
> >  }
> >  
> > +static u8 ts4800_read_reg16(const struct sja1000_priv *priv, int reg)
> > +{
> > +	sp_write_reg16(priv, 0,  reg);
> > +	return sp_read_reg16(priv, 2);
> 
> This is racy, please add a spinlock.
> 
> > +}
> > +
> > +static void ts4800_write_reg16(const struct sja1000_priv *priv, int reg, u8 val)
> > +{
> > +	sp_write_reg16(priv, 0, reg);
> > +	sp_write_reg16(priv, 2, val);
> 
> This is racy, too.
> 
> Have a look at https://marc.info/?l=linux-can&m=137149497403825&w=2

Thank you for the link. In my situation, I don't think there is a race
issue at the bus level, so a per-device spinlock should be enough. Would
that be an acceptable patch? It would look a lot like the patch you
suggested in the thread you linked, just rebased on current version.

Thanks,
Damien

Re: [PATCH 2/2] can: sja1000: of: add compatibility with Technologic Systems version

[Marc Kleine-Budde]

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On 12/18/2015 10:02 PM, Damien Riegel wrote:
> On Fri, Dec 18, 2015 at 09:41:47PM +0100, Marc Kleine-Budde wrote:
>> On 12/18/2015 09:17 PM, Damien Riegel wrote:
>>> Technologic Systems provides an IP compatible with the SJA1000,
>>> instantiated in an FPGA. Because of some bus widths issue, access to
>>> registers is made through a "window" that works like this:
>>>
>>>     base + 0x0: address to read/write
>>>     base + 0x2: 8-bit register value
>>>
>>> This commit adds a new compatible device, "technologic,sja1000", with
>>> read and write functions using the window mechanism.
>>>
>>> Signed-off-by: Damien Riegel <damien.riegel@savoirfairelinux.com>
>>> ---
>>>  drivers/net/can/sja1000/sja1000_platform.c | 30 ++++++++++++++++++++++++++++--
>>>  1 file changed, 28 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/drivers/net/can/sja1000/sja1000_platform.c b/drivers/net/can/sja1000/sja1000_platform.c
>>> index 0552ed4..6cbf251 100644
>>> --- a/drivers/net/can/sja1000/sja1000_platform.c
>>> +++ b/drivers/net/can/sja1000/sja1000_platform.c
>>> @@ -70,6 +70,18 @@ static void sp_write_reg32(const struct sja1000_priv *priv, int reg, u8 val)
>>>  	iowrite8(val, priv->reg_base + reg * 4);
>>>  }
>>>  
>>> +static u8 ts4800_read_reg16(const struct sja1000_priv *priv, int reg)
>>> +{
>>> +	sp_write_reg16(priv, 0,  reg);
>>> +	return sp_read_reg16(priv, 2);
>>
>> This is racy, please add a spinlock.
>>
>>> +}
>>> +
>>> +static void ts4800_write_reg16(const struct sja1000_priv *priv, int reg, u8 val)
>>> +{
>>> +	sp_write_reg16(priv, 0, reg);
>>> +	sp_write_reg16(priv, 2, val);
>>
>> This is racy, too.
>>
>> Have a look at https://marc.info/?l=linux-can&m=137149497403825&w=2
> 
> Thank you for the link. In my situation, I don't think there is a race
> issue at the bus level, so a per-device spinlock should be enough. Would
> that be an acceptable patch? It would look a lot like the patch you
> suggested in the thread you linked, just rebased on current version.

Yes, but for a device spinlock you probably have to remove "const" from
the priv pointer.

Marc

-- 
Pengutronix e.K.                  | Marc Kleine-Budde           |
Industrial Linux Solutions        | Phone: +49-231-2826-924     |
Vertretung West/Dortmund          | Fax:   +49-5121-206917-5555 |
Amtsgericht Hildesheim, HRA 2686  | http://www.pengutronix.de   |


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Re: [PATCH 1/2] can: sja1000: add documentation for Technologic Systems version

[Rob Herring]

On Fri, Dec 18, 2015 at 03:17:24PM -0500, Damien Riegel wrote:
> This commit adds documentation for the Technologic Systems version of
> SJA1000. The difference with the NXP version is in the way the registers
> are accessed.
> 
> Signed-off-by: Damien Riegel <damien.riegel@savoirfairelinux.com>
> ---
>  Documentation/devicetree/bindings/net/can/sja1000.txt | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/Documentation/devicetree/bindings/net/can/sja1000.txt b/Documentation/devicetree/bindings/net/can/sja1000.txt
> index b4a6d53..7a158d5 100644
> --- a/Documentation/devicetree/bindings/net/can/sja1000.txt
> +++ b/Documentation/devicetree/bindings/net/can/sja1000.txt
> @@ -2,7 +2,7 @@ Memory mapped SJA1000 CAN controller from NXP (formerly Philips)
>  
>  Required properties:
>  
> -- compatible : should be "nxp,sja1000".
> +- compatible : should be one of "nxp,sja1000", "technologic,sja1000".
>  
>  - reg : should specify the chip select, address offset and size required
>  	to map the registers of the SJA1000. The size is usually 0x80.
> @@ -14,6 +14,7 @@ Optional properties:
>  
>  - reg-io-width : Specify the size (in bytes) of the IO accesses that
>  	should be performed on the device.  Valid value is 1, 2 or 4.
> +	Must be set to 2 for technologic version.
>  	Default to 1 (8 bits).

Really, this should default to 2 for technologic version and not be 
required.

Rob

Re: [PATCH 1/2] can: sja1000: add documentation for Technologic Systems version

[Damien Riegel]

On Sat, Dec 19, 2015 at 09:37:42PM -0600, Rob Herring wrote:
> On Fri, Dec 18, 2015 at 03:17:24PM -0500, Damien Riegel wrote:
> > This commit adds documentation for the Technologic Systems version of
> > SJA1000. The difference with the NXP version is in the way the registers
> > are accessed.
> > 
> > Signed-off-by: Damien Riegel <damien.riegel@savoirfairelinux.com>
> > ---
> >  Documentation/devicetree/bindings/net/can/sja1000.txt | 3 ++-
> >  1 file changed, 2 insertions(+), 1 deletion(-)
> > 
> > diff --git a/Documentation/devicetree/bindings/net/can/sja1000.txt b/Documentation/devicetree/bindings/net/can/sja1000.txt
> > index b4a6d53..7a158d5 100644
> > --- a/Documentation/devicetree/bindings/net/can/sja1000.txt
> > +++ b/Documentation/devicetree/bindings/net/can/sja1000.txt
> > @@ -2,7 +2,7 @@ Memory mapped SJA1000 CAN controller from NXP (formerly Philips)
> >  
> >  Required properties:
> >  
> > -- compatible : should be "nxp,sja1000".
> > +- compatible : should be one of "nxp,sja1000", "technologic,sja1000".
> >  
> >  - reg : should specify the chip select, address offset and size required
> >  	to map the registers of the SJA1000. The size is usually 0x80.
> > @@ -14,6 +14,7 @@ Optional properties:
> >  
> >  - reg-io-width : Specify the size (in bytes) of the IO accesses that
> >  	should be performed on the device.  Valid value is 1, 2 or 4.
> > +	Must be set to 2 for technologic version.
> >  	Default to 1 (8 bits).
> 
> Really, this should default to 2 for technologic version and not be 
> required.

Would something along the line of "This property is <not used|ignored>
for technologic version." be more appropriate?

Thanks,
Damien

Re: [PATCH 1/2] can: sja1000: add documentation for Technologic Systems version

[Rob Herring]

On Mon, Dec 21, 2015 at 9:09 AM, Damien Riegel
<damien.riegel@savoirfairelinux.com> wrote:
> On Sat, Dec 19, 2015 at 09:37:42PM -0600, Rob Herring wrote:
>> On Fri, Dec 18, 2015 at 03:17:24PM -0500, Damien Riegel wrote:
>> > This commit adds documentation for the Technologic Systems version of
>> > SJA1000. The difference with the NXP version is in the way the registers
>> > are accessed.
>> >
>> > Signed-off-by: Damien Riegel <damien.riegel@savoirfairelinux.com>
>> > ---
>> >  Documentation/devicetree/bindings/net/can/sja1000.txt | 3 ++-
>> >  1 file changed, 2 insertions(+), 1 deletion(-)
>> >
>> > diff --git a/Documentation/devicetree/bindings/net/can/sja1000.txt b/Documentation/devicetree/bindings/net/can/sja1000.txt
>> > index b4a6d53..7a158d5 100644
>> > --- a/Documentation/devicetree/bindings/net/can/sja1000.txt
>> > +++ b/Documentation/devicetree/bindings/net/can/sja1000.txt
>> > @@ -2,7 +2,7 @@ Memory mapped SJA1000 CAN controller from NXP (formerly Philips)
>> >
>> >  Required properties:
>> >
>> > -- compatible : should be "nxp,sja1000".
>> > +- compatible : should be one of "nxp,sja1000", "technologic,sja1000".
>> >
>> >  - reg : should specify the chip select, address offset and size required
>> >     to map the registers of the SJA1000. The size is usually 0x80.
>> > @@ -14,6 +14,7 @@ Optional properties:
>> >
>> >  - reg-io-width : Specify the size (in bytes) of the IO accesses that
>> >     should be performed on the device.  Valid value is 1, 2 or 4.
>> > +   Must be set to 2 for technologic version.
>> >     Default to 1 (8 bits).
>>
>> Really, this should default to 2 for technologic version and not be
>> required.
>
> Would something along the line of "This property is <not used|ignored>
> for technologic version." be more appropriate?

Yes, exactly.

Rob