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[PATCH] net: can: cc770: Simplify parsing DT properties

Rob Herring (Arm) posted 1 patch 1 year, 3 months ago
There is a newer version of this series
drivers/net/can/cc770/cc770_platform.c | 29 ++++++++------------------
1 file changed, 9 insertions(+), 20 deletions(-)
[PATCH] net: can: cc770: Simplify parsing DT properties
Posted by Rob Herring (Arm) 1 year, 3 months ago 
Use of the typed property accessors is preferred over of_get_property().
The existing code doesn't work on little endian systems either. Replace
the of_get_property() calls with of_property_read_bool() and
of_property_read_u32().

Signed-off-by: Rob Herring (Arm) <robh@kernel.org>
---
 drivers/net/can/cc770/cc770_platform.c | 29 ++++++++------------------
 1 file changed, 9 insertions(+), 20 deletions(-)

diff --git a/drivers/net/can/cc770/cc770_platform.c b/drivers/net/can/cc770/cc770_platform.c
index 13bcfba05f18..9993568154f8 100644
--- a/drivers/net/can/cc770/cc770_platform.c
+++ b/drivers/net/can/cc770/cc770_platform.c
@@ -71,16 +71,9 @@ static int cc770_get_of_node_data(struct platform_device *pdev,
 				  struct cc770_priv *priv)
 {
 	struct device_node *np = pdev->dev.of_node;
-	const u32 *prop;
-	int prop_size;
-	u32 clkext;
-
-	prop = of_get_property(np, "bosch,external-clock-frequency",
-			       &prop_size);
-	if (prop && (prop_size ==  sizeof(u32)))
-		clkext = *prop;
-	else
-		clkext = CC770_PLATFORM_CAN_CLOCK; /* default */
+	u32 clkext = CC770_PLATFORM_CAN_CLOCK, clkout = 0;
+
+	of_property_read_u32(np, "bosch,external-clock-frequency", &clkext);
 	priv->can.clock.freq = clkext;
 
 	/* The system clock may not exceed 10 MHz */
@@ -98,7 +91,7 @@ static int cc770_get_of_node_data(struct platform_device *pdev,
 	if (of_property_read_bool(np, "bosch,iso-low-speed-mux"))
 		priv->cpu_interface |= CPUIF_MUX;
 
-	if (!of_get_property(np, "bosch,no-comperator-bypass", NULL))
+	if (!of_property_read_bool(np, "bosch,no-comperator-bypass"))
 		priv->bus_config |= BUSCFG_CBY;
 	if (of_property_read_bool(np, "bosch,disconnect-rx0-input"))
 		priv->bus_config |= BUSCFG_DR0;
@@ -109,20 +102,16 @@ static int cc770_get_of_node_data(struct platform_device *pdev,
 	if (of_property_read_bool(np, "bosch,polarity-dominant"))
 		priv->bus_config |= BUSCFG_POL;
 
-	prop = of_get_property(np, "bosch,clock-out-frequency", &prop_size);
-	if (prop && (prop_size == sizeof(u32)) && *prop > 0) {
-		u32 cdv = clkext / *prop;
-		int slew;
+	of_property_read_u32(np, "bosch,clock-out-frequency", &clkout);
+	if (clkout > 0) {
+		u32 cdv = clkext / clkout;
+		u32 slew;
 
 		if (cdv > 0 && cdv < 16) {
 			priv->cpu_interface |= CPUIF_CEN;
 			priv->clkout |= (cdv - 1) & CLKOUT_CD_MASK;
 
-			prop = of_get_property(np, "bosch,slew-rate",
-					       &prop_size);
-			if (prop && (prop_size == sizeof(u32))) {
-				slew = *prop;
-			} else {
+			if (of_property_read_u32(np, "bosch,slew-rate", &slew)) {
 				/* Determine default slew rate */
 				slew = (CLKOUT_SL_MASK >>
 					CLKOUT_SL_SHIFT) -
-- 
2.45.2
Re: [PATCH] net: can: cc770: Simplify parsing DT properties
Posted by Simon Horman 1 year, 3 months ago 
On Wed, Aug 28, 2024 at 08:19:02AM -0500, Rob Herring (Arm) wrote:
> Use of the typed property accessors is preferred over of_get_property().
> The existing code doesn't work on little endian systems either. Replace
> the of_get_property() calls with of_property_read_bool() and
> of_property_read_u32().
> 
> Signed-off-by: Rob Herring (Arm) <robh@kernel.org>

...

> diff --git a/drivers/net/can/cc770/cc770_platform.c b/drivers/net/can/cc770/cc770_platform.c
> index 13bcfba05f18..9993568154f8 100644
> --- a/drivers/net/can/cc770/cc770_platform.c
> +++ b/drivers/net/can/cc770/cc770_platform.c
> @@ -71,16 +71,9 @@ static int cc770_get_of_node_data(struct platform_device *pdev,
>  				  struct cc770_priv *priv)
>  {
>  	struct device_node *np = pdev->dev.of_node;
> -	const u32 *prop;
> -	int prop_size;
> -	u32 clkext;
> -
> -	prop = of_get_property(np, "bosch,external-clock-frequency",
> -			       &prop_size);
> -	if (prop && (prop_size ==  sizeof(u32)))
> -		clkext = *prop;
> -	else
> -		clkext = CC770_PLATFORM_CAN_CLOCK; /* default */
> +	u32 clkext = CC770_PLATFORM_CAN_CLOCK, clkout = 0;

Marc,

Could you clarify if reverse xmas tree ordering - longest line to shortest
- of local variables is desired for can code? If so, I'm flagging that the
above now doesn't follow that scheme.

> +
> +	of_property_read_u32(np, "bosch,external-clock-frequency", &clkext);
>  	priv->can.clock.freq = clkext;
>  
>  	/* The system clock may not exceed 10 MHz */

...

> @@ -109,20 +102,16 @@ static int cc770_get_of_node_data(struct platform_device *pdev,
>  	if (of_property_read_bool(np, "bosch,polarity-dominant"))
>  		priv->bus_config |= BUSCFG_POL;
>  
> -	prop = of_get_property(np, "bosch,clock-out-frequency", &prop_size);
> -	if (prop && (prop_size == sizeof(u32)) && *prop > 0) {
> -		u32 cdv = clkext / *prop;
> -		int slew;
> +	of_property_read_u32(np, "bosch,clock-out-frequency", &clkout);
> +	if (clkout > 0) {
> +		u32 cdv = clkext / clkout;
> +		u32 slew;
>  
>  		if (cdv > 0 && cdv < 16) {
>  			priv->cpu_interface |= CPUIF_CEN;
>  			priv->clkout |= (cdv - 1) & CLKOUT_CD_MASK;
>  
> -			prop = of_get_property(np, "bosch,slew-rate",
> -					       &prop_size);
> -			if (prop && (prop_size == sizeof(u32))) {
> -				slew = *prop;
> -			} else {
> +			if (of_property_read_u32(np, "bosch,slew-rate", &slew)) {
>  				/* Determine default slew rate */
>  				slew = (CLKOUT_SL_MASK >>
>  					CLKOUT_SL_SHIFT) -

Rob,

The next few lines look like this:

					((cdv * clkext - 1) / 8000000);
				if (slew < 0)
					slew = 0;

But slew is now unsigned, so this check will always be false.

Flagged by Smatch and Coccinelle.
Re: [PATCH] net: can: cc770: Simplify parsing DT properties
Posted by Marc Kleine-Budde 1 year, 3 months ago 
On 28.08.2024 17:16:24, Simon Horman wrote:
> On Wed, Aug 28, 2024 at 08:19:02AM -0500, Rob Herring (Arm) wrote:
> > Use of the typed property accessors is preferred over of_get_property().
> > The existing code doesn't work on little endian systems either. Replace
> > the of_get_property() calls with of_property_read_bool() and
> > of_property_read_u32().
> > 
> > Signed-off-by: Rob Herring (Arm) <robh@kernel.org>
> 
> ...
> 
> > diff --git a/drivers/net/can/cc770/cc770_platform.c b/drivers/net/can/cc770/cc770_platform.c
> > index 13bcfba05f18..9993568154f8 100644
> > --- a/drivers/net/can/cc770/cc770_platform.c
> > +++ b/drivers/net/can/cc770/cc770_platform.c
> > @@ -71,16 +71,9 @@ static int cc770_get_of_node_data(struct platform_device *pdev,
> >  				  struct cc770_priv *priv)
> >  {
> >  	struct device_node *np = pdev->dev.of_node;
> > -	const u32 *prop;
> > -	int prop_size;
> > -	u32 clkext;
> > -
> > -	prop = of_get_property(np, "bosch,external-clock-frequency",
> > -			       &prop_size);
> > -	if (prop && (prop_size ==  sizeof(u32)))
> > -		clkext = *prop;
> > -	else
> > -		clkext = CC770_PLATFORM_CAN_CLOCK; /* default */
> > +	u32 clkext = CC770_PLATFORM_CAN_CLOCK, clkout = 0;
> 
> Marc,
> 
> Could you clarify if reverse xmas tree ordering - longest line to shortest
> - of local variables is desired for can code? If so, I'm flagging that the
> above now doesn't follow that scheme.

If you touch the code, and noting speaks against it, please make it
reverse xmas.

> 
> > +
> > +	of_property_read_u32(np, "bosch,external-clock-frequency", &clkext);
> >  	priv->can.clock.freq = clkext;
> >  
> >  	/* The system clock may not exceed 10 MHz */
> 
> ...
> 
> > @@ -109,20 +102,16 @@ static int cc770_get_of_node_data(struct platform_device *pdev,
> >  	if (of_property_read_bool(np, "bosch,polarity-dominant"))
> >  		priv->bus_config |= BUSCFG_POL;
> >  
> > -	prop = of_get_property(np, "bosch,clock-out-frequency", &prop_size);
> > -	if (prop && (prop_size == sizeof(u32)) && *prop > 0) {
> > -		u32 cdv = clkext / *prop;
> > -		int slew;
> > +	of_property_read_u32(np, "bosch,clock-out-frequency", &clkout);
> > +	if (clkout > 0) {
> > +		u32 cdv = clkext / clkout;
> > +		u32 slew;
> >  
> >  		if (cdv > 0 && cdv < 16) {
> >  			priv->cpu_interface |= CPUIF_CEN;
> >  			priv->clkout |= (cdv - 1) & CLKOUT_CD_MASK;
> >  
> > -			prop = of_get_property(np, "bosch,slew-rate",
> > -					       &prop_size);
> > -			if (prop && (prop_size == sizeof(u32))) {
> > -				slew = *prop;
> > -			} else {
> > +			if (of_property_read_u32(np, "bosch,slew-rate", &slew)) {
> >  				/* Determine default slew rate */
> >  				slew = (CLKOUT_SL_MASK >>
> >  					CLKOUT_SL_SHIFT) -
> 
> Rob,
> 
> The next few lines look like this:
> 
> 					((cdv * clkext - 1) / 8000000);
> 				if (slew < 0)
> 					slew = 0;
> 
> But slew is now unsigned, so this check will always be false.
> 
> Flagged by Smatch and Coccinelle.

Good finding.

Thanks,
Marc

-- 
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