linux-kernel - Re: Re[10]: [PATCH v3] mfd: syscon: Add non-DT support

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Date:	Wed, 20 Feb 2013 15:00:18 +0000
From:	Arnd Bergmann <arnd@...db.de>
To:	Alexander Shiyan <shc_work@...l.ru>
Cc:	Dong Aisheng <dong.aisheng@...aro.org>,
	linux-kernel@...r.kernel.org, Samuel Ortiz <sameo@...ux.intel.com>,
	Mark Brown <broonie@...nsource.wolfsonmicro.com>
Subject: Re: Re[10]: [PATCH v3] mfd: syscon: Add non-DT support

On Wednesday 20 February 2013, Alexander Shiyan wrote:
> OK. I can convert platform to DT, no so easy, but possible.
> But I will use syscon as way to using DT (and MULTIPLATFORM in the future),
> this mean that I should completely drop ATAG support from this platform
> (since I cannot use syscon device without DT support, but several platform devices
> need to use system-wide registers).
> Arnd, if its OK for you, I will use this way. (I talking about CLPS711X, you know it :) ).

Ah, I should have realized that this is about clps711x when the patch
is coming from you ;-)

This is an existing platform, and I would not require you to move it to
devicetree just for supporting syscon, although it may be a good idea
to make that move in the long run.

For clps711x, we know that there is only one syscon register set, so you
could do a very simple patch like below. Basically we don't need to
treat the absence of DT information as an error, and a call to
syscon_regmap_lookup_by_compatible or syscon_regmap_lookup_by_phandle
will always return the syscon device that was registered first, or
-EPROBE_DEFER for any error.

	Arnd


diff --git a/drivers/mfd/syscon.c b/drivers/mfd/syscon.c
index 3f10591..d3c06c6 100644
--- a/drivers/mfd/syscon.c
+++ b/drivers/mfd/syscon.c
@@ -59,9 +59,6 @@ struct regmap *syscon_regmap_lookup_by_compatible(const char *s)
 	struct regmap *regmap;
 
 	syscon_np = of_find_compatible_node(NULL, NULL, s);
-	if (!syscon_np)
-		return ERR_PTR(-ENODEV);
-
 	regmap = syscon_node_to_regmap(syscon_np);
 	of_node_put(syscon_np);
 
@@ -76,9 +73,6 @@ struct regmap *syscon_regmap_lookup_by_phandle(struct device_node *np,
 	struct regmap *regmap;
 
 	syscon_np = of_parse_phandle(np, property, 0);
-	if (!syscon_np)
-		return ERR_PTR(-ENODEV);
-
 	regmap = syscon_node_to_regmap(syscon_np);
 	of_node_put(syscon_np);
 
@@ -100,26 +94,22 @@ static struct regmap_config syscon_regmap_config = {
 static int syscon_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
-	struct device_node *np = dev->of_node;
 	struct syscon *syscon;
-	struct resource res;
+	struct resource *res;
 	int ret;
 
-	if (!np)
-		return -ENOENT;
-
 	syscon = devm_kzalloc(dev, sizeof(struct syscon),
 			    GFP_KERNEL);
 	if (!syscon)
 		return -ENOMEM;
 
-	syscon->base = of_iomap(np, 0);
-	if (!syscon->base)
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res)
 		return -EADDRNOTAVAIL;
 
-	ret = of_address_to_resource(np, 0, &res);
-	if (ret)
-		return ret;
+	syscon->base = devm_ioremap(&pdev->dev, res->start, resource_size(res));
+	if (!syscon->base)
+		return -ENOMEM;
 
 	syscon_regmap_config.max_register = res.end - res.start - 3;
 	syscon->regmap = devm_regmap_init_mmio(dev, syscon->base,
--
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