[PATCH 2/3] Driver for user access to internal clocks

[PATCH 2/3] Driver for user access to internal clocks

[Davide Rizzo]

Specific for Samsung S3C24xx platforms
Allows any driver to get a device specific clock.
It recognizes also the form clkname.X

Signed-off-by: Davide Rizzo <elpa-rizzo@gmail.com>
---
diff -urNp linux-2.6.28/arch/arm/plat-s3c24xx/clock.c
linux-2.6.28.elpa/arch/arm/plat-s3c24xx/clock.c
--- linux-2.6.28/arch/arm/plat-s3c24xx/clock.c	2008-12-25
00:26:37.000000000 +0100
+++ linux-2.6.28.elpa/arch/arm/plat-s3c24xx/clock.c	2009-01-07
19:25:07.000000000 +0100
@@ -67,11 +67,19 @@ static int clk_null_enable(struct clk *c

 struct clk *clk_get(struct device *dev, const char *id)
 {
+	long idno;
+	char *name = (char *)id;
+	char *dotpos = strrchr(id, '.');
 	struct clk *p;
 	struct clk *clk = ERR_PTR(-ENOENT);
-	int idno;

-	if (dev == NULL || dev->bus != &platform_bus_type)
+	if (dotpos) {
+		int err = strict_strtol(dotpos + 1, 10, &idno);
+		if (err)
+			return ERR_PTR(err);
+		name = kstrdup(id, GFP_KERNEL);
+		name[dotpos - id] = '\0';
+	} else if (dev == NULL || dev->bus != &platform_bus_type)
 		idno = -1;
 	else
 		idno = to_platform_device(dev)->id;
@@ -80,7 +88,7 @@ struct clk *clk_get(struct device *dev,

 	list_for_each_entry(p, &clocks, list) {
 		if (p->id == idno &&
-		    strcmp(id, p->name) == 0 &&
+		    strcmp(name, p->name) == 0 &&
 		    try_module_get(p->owner)) {
 			clk = p;
 			break;
@@ -92,7 +100,7 @@ struct clk *clk_get(struct device *dev,

 	if (IS_ERR(clk)) {
 		list_for_each_entry(p, &clocks, list) {
-			if (p->id == -1 && strcmp(id, p->name) == 0 &&
+			if (p->id == -1 && strcmp(name, p->name) == 0 &&
 			    try_module_get(p->owner)) {
 				clk = p;
 				break;
@@ -101,6 +109,9 @@ struct clk *clk_get(struct device *dev,
 	}

 	mutex_unlock(&clocks_mutex);
+
+	if (dotpos)
+		kfree(name);
 	return clk;
 }

Re: [PATCH 2/3] Driver for user access to internal clocks

[Ben Dooks]

On Thu, Jan 08, 2009 at 10:50:03AM +0100, Davide Rizzo wrote:
> Specific for Samsung S3C24xx platforms
> Allows any driver to get a device specific clock.
> It recognizes also the form clkname.X
> 
> Signed-off-by: Davide Rizzo <elpa-rizzo@gmail.com>
> ---
> diff -urNp linux-2.6.28/arch/arm/plat-s3c24xx/clock.c
> linux-2.6.28.elpa/arch/arm/plat-s3c24xx/clock.c
> --- linux-2.6.28/arch/arm/plat-s3c24xx/clock.c	2008-12-25
> 00:26:37.000000000 +0100
> +++ linux-2.6.28.elpa/arch/arm/plat-s3c24xx/clock.c	2009-01-07
> 19:25:07.000000000 +0100
> @@ -67,11 +67,19 @@ static int clk_null_enable(struct clk *c
> 
>  struct clk *clk_get(struct device *dev, const char *id)
>  {
> +	long idno;
> +	char *name = (char *)id;
> +	char *dotpos = strrchr(id, '.');

you've borken the const of the clk_get() call. I think that
this is either something that the caller needs to deal with
as all the drivers will be passing a 'dev' structure in to
help identify common clocks. 

>  	struct clk *p;
>  	struct clk *clk = ERR_PTR(-ENOENT);
> -	int idno;
> 
> -	if (dev == NULL || dev->bus != &platform_bus_type)
> +	if (dotpos) {
> +		int err = strict_strtol(dotpos + 1, 10, &idno);
> +		if (err)
> +			return ERR_PTR(err);
> +		name = kstrdup(id, GFP_KERNEL);
> +		name[dotpos - id] = '\0';
> +	} else if (dev == NULL || dev->bus != &platform_bus_type)
>  		idno = -1;
>  	else
>  		idno = to_platform_device(dev)->id;
> @@ -80,7 +88,7 @@ struct clk *clk_get(struct device *dev,
> 
>  	list_for_each_entry(p, &clocks, list) {
>  		if (p->id == idno &&
> -		    strcmp(id, p->name) == 0 &&
> +		    strcmp(name, p->name) == 0 &&
>  		    try_module_get(p->owner)) {
>  			clk = p;
>  			break;
> @@ -92,7 +100,7 @@ struct clk *clk_get(struct device *dev,
> 
>  	if (IS_ERR(clk)) {
>  		list_for_each_entry(p, &clocks, list) {
> -			if (p->id == -1 && strcmp(id, p->name) == 0 &&
> +			if (p->id == -1 && strcmp(name, p->name) == 0 &&
>  			    try_module_get(p->owner)) {
>  				clk = p;
>  				break;
> @@ -101,6 +109,9 @@ struct clk *clk_get(struct device *dev,
>  	}
> 
>  	mutex_unlock(&clocks_mutex);
> +
> +	if (dotpos)
> +		kfree(name);
>  	return clk;
>  }
> --
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-- 
Ben (ben@fluff.org, http://www.fluff.org/)

  'a smiley only costs 4 bytes'

Re: [PATCH 2/3] Driver for user access to internal clocks

[Davide Rizzo]

> you've borken the const of the clk_get() call. I think that
> this is either something that the caller needs to deal with
> as all the drivers will be passing a 'dev' structure in to
> help identify common clocks.
>
As I modified it the clk_get() function it should be compatible with
the past, simply now it recognizes ALSO the format clkname.X to allow
a generic driver to have access to all clocks.
The other way to achieve this is to simulate a specific id in a fake
dev parameter, but it's awful.
For the driver to be generic, all low-level drivers should recognize
the clkname.X format. But this is the standard syntax for devices
name, so I think this should be correct.
Also clk_for_each() and clk_name() should be added to clock
infrastructure, so they should be implemented in all drivers.
Maybe this should be proposed and discussed with the clock
infrastructure maintainer, but I didn't find him in the MAINTAINER
list. Do you know who is ?
Where do you think the generic user access driver should be placed ?