[RFC PATCH 0/2] mfd: syscon: declare holes in syscon register maps

[RFC PATCH 0/2] mfd: syscon: declare holes in syscon register maps

[Seraphin Bonnaffe]

In reply to mail: Holes management in syscon driver. 

Hi Dong, Maxime, Lee, all,

Regmap also offers .rd_table and .wr_table structures that can be used to
specify valid ranges within agiven regmap configuration.

This patch uses these structures to declare holes in a syscon instance.
It takes the description from DT, and fills in the structures accordingly.

Can I have your opinion on this implementation ?

Thanks and Regards,
Seraphin

Seraphin Bonnaffe (2):
  mfd: syscon: Document new DT binding "holes"
  mfd: syscon: specify rd_table and wr_table from DT

 Documentation/devicetree/bindings/mfd/syscon.txt |  5 ++++
 drivers/mfd/syscon.c                             | 35 ++++++++++++++++++++++++
 2 files changed, 40 insertions(+)

-- 
1.9.1

[RFC PATCH 1/2] mfd: syscon: Document new DT binding "holes"

[Seraphin Bonnaffe]

This patch adds DT bindings to declare holes in syscon register maps.

Signed-off-by: Seraphin Bonnaffe <seraphin.bonnaffe@st.com>
---
 Documentation/devicetree/bindings/mfd/syscon.txt | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/Documentation/devicetree/bindings/mfd/syscon.txt b/Documentation/devicetree/bindings/mfd/syscon.txt
index fe8150b..80ab9ca 100644
--- a/Documentation/devicetree/bindings/mfd/syscon.txt
+++ b/Documentation/devicetree/bindings/mfd/syscon.txt
@@ -13,8 +13,13 @@ Required properties:
 - compatible: Should contain "syscon".
 - reg: the register region can be accessed from syscon
 
+Optional properties:
+- holes: Register regions that cannot be accessed within reg range.
+	 Each hole is described with its offset address, followed by its size.
+
 Examples:
 gpr: iomuxc-gpr@020e0000 {
 	compatible = "fsl,imx6q-iomuxc-gpr", "syscon";
 	reg = <0x020e0000 0x38>;
+	holes = <0x000c 0x8 0x020 0x4>;
 };
-- 
1.9.1

[RFC PATCH 2/2] mfd: syscon: specify rd_table and wr_table from DT

[Seraphin Bonnaffe]

The syscon driver is based on regmap, which offers the possibility to
declare registers as readable/writable or not, thanks to rd_table and
wr_table.

This patch takes register map's holes description from DT, and fills in
the rd_table and wr_table of the corresponding syson instance accordingly.

Signed-off-by: Seraphin Bonnaffe <seraphin.bonnaffe@st.com>
---
 drivers/mfd/syscon.c | 35 +++++++++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)

diff --git a/drivers/mfd/syscon.c b/drivers/mfd/syscon.c
index ca15878..2bfb45d 100644
--- a/drivers/mfd/syscon.c
+++ b/drivers/mfd/syscon.c
@@ -125,9 +125,15 @@ static int syscon_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
 	struct syscon_platform_data *pdata = dev_get_platdata(dev);
+	struct device_node *np = dev->of_node;
+	struct regmap_access_table *syscon_rw_table;
+	struct regmap_range *holes;
 	struct syscon *syscon;
 	struct resource *res;
 	void __iomem *base;
+	const __be32 *hole_prop;
+	u32 min, max, size;
+	u32 i, hlen, ngaps;
 
 	syscon = devm_kzalloc(dev, sizeof(*syscon), GFP_KERNEL);
 	if (!syscon)
@@ -141,6 +147,35 @@ static int syscon_probe(struct platform_device *pdev)
 	if (!base)
 		return -ENOMEM;
 
+	hole_prop = of_get_property(np, "holes", &hlen);
+	if (hole_prop) {
+		hlen /= sizeof(*hole_prop);
+		ngaps = hlen / 2;
+
+		holes =  devm_kzalloc(dev, ngaps * sizeof(*holes), GFP_KERNEL);
+		if (!holes)
+			return -ENOMEM;
+
+		for (i = 0; i < ngaps; i++) {
+			min = (u32)of_read_number(&hole_prop[i * 2], 1);
+			size = (u32)of_read_number(&hole_prop[i * 2 + 1], 1);
+			max = min + size - 1;
+
+			holes[i].range_min = min;
+			holes[i].range_max = max;
+		}
+		syscon_rw_table = devm_kzalloc(dev, sizeof(*syscon_rw_table),
+					       GFP_KERNEL);
+		if (!syscon_rw_table)
+			return -ENOMEM;
+
+		syscon_rw_table->no_ranges = holes;
+		syscon_rw_table->n_no_ranges = ngaps;
+
+		syscon_regmap_config.rd_table = syscon_rw_table;
+		syscon_regmap_config.wr_table = syscon_rw_table;
+	}
+
 	syscon_regmap_config.max_register = res->end - res->start - 3;
 	if (pdata)
 		syscon_regmap_config.name = pdata->label;
-- 
1.9.1

Re: [RFC PATCH 0/2] mfd: syscon: declare holes in syscon register maps

[Maxime Coquelin]

Hi Seraphin,

On 10/07/2014 03:22 PM, Seraphin Bonnaffe wrote:
> In reply to mail: Holes management in syscon driver.
> 
> Hi Dong, Maxime, Lee, all,
> 
> Regmap also offers .rd_table and .wr_table structures that can be used to
> specify valid ranges within agiven regmap configuration.
> 
> This patch uses these structures to declare holes in a syscon instance.
> It takes the description from DT, and fills in the structures accordingly.
> 
> Can I have your opinion on this implementation ?

As discussed face to face, it looks fine to me.

But we would like green light in the new "holes" property introduced.

Thanks,
Maxime

> 
> Thanks and Regards,
> Seraphin
> 
> Seraphin Bonnaffe (2):
>    mfd: syscon: Document new DT binding "holes"
>    mfd: syscon: specify rd_table and wr_table from DT
> 
>   Documentation/devicetree/bindings/mfd/syscon.txt |  5 ++++
>   drivers/mfd/syscon.c                             | 35 ++++++++++++++++++++++++
>   2 files changed, 40 insertions(+)
>