[PATCH v2 0/2] bus: imx-weim

[PATCH v2 0/2] bus: imx-weim

[thesven73]

From: Sven Van Asbroeck <TheSven73@googlemail.com>

Support multiple address ranges per child node on imx-weim.
While we're at it, insert some code which guards against common config
conflicts.

v2:
	corrected acme@... in commit message example

Sven Van Asbroeck (2):
  bus: imx-weim: support multiple address ranges per child node
  bus: imx-weim: guard against timing configuration conflicts

 drivers/bus/imx-weim.c | 69 +++++++++++++++++++++++++++++++++---------
 1 file changed, 55 insertions(+), 14 deletions(-)

-- 
2.17.1

[PATCH v2 1/2] bus: imx-weim: support multiple address ranges per child node

[thesven73]

From: Sven Van Asbroeck <TheSven73@googlemail.com>

Ensure that timing values for the child node are applied to
all chip selects in the child's address ranges.

Note that this does not support multiple timing settings per
child; this can be added in the future if required.

Example:
&weim {
	acme@0,0 {
		compatible = "acme,whatever";
		reg = <0 0 0x100>, <0 0x400000 0x800>,
				<1 0x400000 0x800>;
		fsl,weim-cs-timing = <0x024400b1 0x00001010 0x20081100
				0x00000000 0xa0000240 0x00000000>;
	};
};

Signed-off-by: Sven Van Asbroeck <TheSven73@googlemail.com>
---
 drivers/bus/imx-weim.c | 36 +++++++++++++++++++++++++-----------
 1 file changed, 25 insertions(+), 11 deletions(-)

diff --git a/drivers/bus/imx-weim.c b/drivers/bus/imx-weim.c
index f01308172de9..24f22285395d 100644
--- a/drivers/bus/imx-weim.c
+++ b/drivers/bus/imx-weim.c
@@ -46,6 +46,7 @@ static const struct imx_weim_devtype imx51_weim_devtype = {
 };
 
 #define MAX_CS_REGS_COUNT	6
+#define OF_REG_SIZE		3
 
 static const struct of_device_id weim_id_table[] = {
 	/* i.MX1/21 */
@@ -115,27 +116,40 @@ static int __init weim_timing_setup(struct device_node *np, void __iomem *base,
 				    const struct imx_weim_devtype *devtype)
 {
 	u32 cs_idx, value[MAX_CS_REGS_COUNT];
-	int i, ret;
+	int i, ret, reg_idx, num_regs;
 
 	if (WARN_ON(devtype->cs_regs_count > MAX_CS_REGS_COUNT))
 		return -EINVAL;
 
-	/* get the CS index from this child node's "reg" property. */
-	ret = of_property_read_u32(np, "reg", &cs_idx);
+	ret = of_property_read_u32_array(np, "fsl,weim-cs-timing",
+					 value, devtype->cs_regs_count);
 	if (ret)
 		return ret;
 
-	if (cs_idx >= devtype->cs_count)
+	/*
+	 * the child node's "reg" property may contain multiple address ranges,
+	 * extract the chip select for each.
+	 */
+	num_regs = of_property_count_elems_of_size(np, "reg", OF_REG_SIZE);
+	if (num_regs < 0)
+		return num_regs;
+	if (!num_regs)
 		return -EINVAL;
+	for (reg_idx = 0; reg_idx < num_regs; reg_idx++) {
+		/* get the CS index from this child node's "reg" property. */
+		ret = of_property_read_u32_index(np, "reg",
+					reg_idx*OF_REG_SIZE, &cs_idx);
+		if (ret)
+			break;
 
-	ret = of_property_read_u32_array(np, "fsl,weim-cs-timing",
-					 value, devtype->cs_regs_count);
-	if (ret)
-		return ret;
+		if (cs_idx >= devtype->cs_count)
+			return -EINVAL;
 
-	/* set the timing for WEIM */
-	for (i = 0; i < devtype->cs_regs_count; i++)
-		writel(value[i], base + cs_idx * devtype->cs_stride + i * 4);
+		/* set the timing for WEIM */
+		for (i = 0; i < devtype->cs_regs_count; i++)
+			writel(value[i],
+				base + cs_idx * devtype->cs_stride + i * 4);
+	}
 
 	return 0;
 }
-- 
2.17.1

[PATCH v2 2/2] bus: imx-weim: guard against timing configuration conflicts

[thesven73]

From: Sven Van Asbroeck <TheSven73@googlemail.com>

When adding weim child devices, there is a risk that the developer will
(by mistake) specify more than one timing setting for the same chip select.

The driver cannot support such a configuration.

In case of conflict, this patch will print a warning to the log,
and will ignore the child node in question.

In this example, node acme@1 will be ignored, as it tries to modify
timing settings for CS0:

&weim {
	acme@0,0 {
		compatible = "acme,whatever";
		reg = <0 0 0x100>;
		fsl,weim-cs-timing = <something>;
	};
	acme@0,500 {
		compatible = "acme,whatnot";
		reg = <0 0x500 0x100>;
		fsl,weim-cs-timing = <something else>;
	};
};

However in this example, the driver will be happy:

&weim {
        acme@0,0 {
                compatible = "acme,whatever";
                reg = <0 0 0x100>;
                fsl,weim-cs-timing = <something>;
        };
        acme@0,500 {
                compatible = "acme,whatnot";
                reg = <0 0x500 0x100>;
                fsl,weim-cs-timing = <something>;
        };
};

Signed-off-by: Sven Van Asbroeck <TheSven73@googlemail.com>
---
 drivers/bus/imx-weim.c | 33 ++++++++++++++++++++++++++++++---
 1 file changed, 30 insertions(+), 3 deletions(-)

diff --git a/drivers/bus/imx-weim.c b/drivers/bus/imx-weim.c
index 24f22285395d..114e503ec785 100644
--- a/drivers/bus/imx-weim.c
+++ b/drivers/bus/imx-weim.c
@@ -46,8 +46,18 @@ static const struct imx_weim_devtype imx51_weim_devtype = {
 };
 
 #define MAX_CS_REGS_COUNT	6
+#define MAX_CS_REGS		6
 #define OF_REG_SIZE		3
 
+struct cs_timing {
+	bool is_applied;
+	u32 regs[MAX_CS_REGS_COUNT];
+};
+
+struct cs_timing_state {
+	struct cs_timing cs[MAX_CS_REGS];
+};
+
 static const struct of_device_id weim_id_table[] = {
 	/* i.MX1/21 */
 	{ .compatible = "fsl,imx1-weim", .data = &imx1_weim_devtype, },
@@ -112,11 +122,14 @@ static int __init imx_weim_gpr_setup(struct platform_device *pdev)
 }
 
 /* Parse and set the timing for this device. */
-static int __init weim_timing_setup(struct device_node *np, void __iomem *base,
-				    const struct imx_weim_devtype *devtype)
+static int __init weim_timing_setup(struct device *dev,
+				    struct device_node *np, void __iomem *base,
+				    const struct imx_weim_devtype *devtype,
+				    struct cs_timing_state *ts)
 {
 	u32 cs_idx, value[MAX_CS_REGS_COUNT];
 	int i, ret, reg_idx, num_regs;
+	struct cs_timing *cst;
 
 	if (WARN_ON(devtype->cs_regs_count > MAX_CS_REGS_COUNT))
 		return -EINVAL;
@@ -145,10 +158,23 @@ static int __init weim_timing_setup(struct device_node *np, void __iomem *base,
 		if (cs_idx >= devtype->cs_count)
 			return -EINVAL;
 
+		/* prevent re-configuring a CS that's already been configured */
+		cst = &ts->cs[cs_idx];
+		if (cst->is_applied && memcmp(value, cst->regs,
+					devtype->cs_regs_count*sizeof(u32))) {
+			dev_err(dev, "fsl,weim-cs-timing conflict on %pOF", np);
+			return -EINVAL;
+		}
+
 		/* set the timing for WEIM */
 		for (i = 0; i < devtype->cs_regs_count; i++)
 			writel(value[i],
 				base + cs_idx * devtype->cs_stride + i * 4);
+		if (!cst->is_applied) {
+			cst->is_applied = true;
+			memcpy(cst->regs, value,
+				devtype->cs_regs_count*sizeof(u32));
+		}
 	}
 
 	return 0;
@@ -165,6 +191,7 @@ static int __init weim_parse_dt(struct platform_device *pdev,
 	const struct imx_weim_devtype *devtype = of_id->data;
 	struct device_node *child;
 	int ret, have_child = 0;
+	struct cs_timing_state ts = {};
 
 	if (devtype == &imx50_weim_devtype) {
 		ret = imx_weim_gpr_setup(pdev);
@@ -179,7 +206,7 @@ static int __init weim_parse_dt(struct platform_device *pdev,
 	}
 
 	for_each_available_child_of_node(pdev->dev.of_node, child) {
-		ret = weim_timing_setup(child, base, devtype);
+		ret = weim_timing_setup(&pdev->dev, child, base, devtype, &ts);
 		if (ret)
 			dev_warn(&pdev->dev, "%pOF set timing failed.\n",
 				child);
-- 
2.17.1

Re: [PATCH v2 1/2] bus: imx-weim: support multiple address ranges per child node

[Shawn Guo]

On Fri, Nov 30, 2018 at 03:56:23PM -0500, thesven73@gmail.com wrote:
> From: Sven Van Asbroeck <TheSven73@googlemail.com>
> 
> Ensure that timing values for the child node are applied to
> all chip selects in the child's address ranges.
> 
> Note that this does not support multiple timing settings per
> child; this can be added in the future if required.
> 
> Example:
> &weim {
> 	acme@0,0 {
> 		compatible = "acme,whatever";
> 		reg = <0 0 0x100>, <0 0x400000 0x800>,
> 				<1 0x400000 0x800>;
> 		fsl,weim-cs-timing = <0x024400b1 0x00001010 0x20081100
> 				0x00000000 0xa0000240 0x00000000>;
> 	};
> };

I'm not sure about that.  Shouldn't we have another child node for
different chip select, something like below?

&weim {
 	acme@0,0 {
 		compatible = "acme,whatever";
 		reg = <0 0 0x100>, <0 0x400000 0x800>;
 		fsl,weim-cs-timing = <0x024400b1 0x00001010 0x20081100
 				      0x00000000 0xa0000240 0x00000000>;
 	};

 	acme@1,400000 {
 		compatible = "acme,whatever";
 		reg = <1 0x400000 0x800>;
 		fsl,weim-cs-timing = <0x024400b1 0x00001010 0x20081100
 				      0x00000000 0xa0000240 0x00000000>;
 	};

Shawn

> 
> Signed-off-by: Sven Van Asbroeck <TheSven73@googlemail.com>
> ---
>  drivers/bus/imx-weim.c | 36 +++++++++++++++++++++++++-----------
>  1 file changed, 25 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/bus/imx-weim.c b/drivers/bus/imx-weim.c
> index f01308172de9..24f22285395d 100644
> --- a/drivers/bus/imx-weim.c
> +++ b/drivers/bus/imx-weim.c
> @@ -46,6 +46,7 @@ static const struct imx_weim_devtype imx51_weim_devtype = {
>  };
>  
>  #define MAX_CS_REGS_COUNT	6
> +#define OF_REG_SIZE		3
>  
>  static const struct of_device_id weim_id_table[] = {
>  	/* i.MX1/21 */
> @@ -115,27 +116,40 @@ static int __init weim_timing_setup(struct device_node *np, void __iomem *base,
>  				    const struct imx_weim_devtype *devtype)
>  {
>  	u32 cs_idx, value[MAX_CS_REGS_COUNT];
> -	int i, ret;
> +	int i, ret, reg_idx, num_regs;
>  
>  	if (WARN_ON(devtype->cs_regs_count > MAX_CS_REGS_COUNT))
>  		return -EINVAL;
>  
> -	/* get the CS index from this child node's "reg" property. */
> -	ret = of_property_read_u32(np, "reg", &cs_idx);
> +	ret = of_property_read_u32_array(np, "fsl,weim-cs-timing",
> +					 value, devtype->cs_regs_count);
>  	if (ret)
>  		return ret;
>  
> -	if (cs_idx >= devtype->cs_count)
> +	/*
> +	 * the child node's "reg" property may contain multiple address ranges,
> +	 * extract the chip select for each.
> +	 */
> +	num_regs = of_property_count_elems_of_size(np, "reg", OF_REG_SIZE);
> +	if (num_regs < 0)
> +		return num_regs;
> +	if (!num_regs)
>  		return -EINVAL;
> +	for (reg_idx = 0; reg_idx < num_regs; reg_idx++) {
> +		/* get the CS index from this child node's "reg" property. */
> +		ret = of_property_read_u32_index(np, "reg",
> +					reg_idx*OF_REG_SIZE, &cs_idx);
> +		if (ret)
> +			break;
>  
> -	ret = of_property_read_u32_array(np, "fsl,weim-cs-timing",
> -					 value, devtype->cs_regs_count);
> -	if (ret)
> -		return ret;
> +		if (cs_idx >= devtype->cs_count)
> +			return -EINVAL;
>  
> -	/* set the timing for WEIM */
> -	for (i = 0; i < devtype->cs_regs_count; i++)
> -		writel(value[i], base + cs_idx * devtype->cs_stride + i * 4);
> +		/* set the timing for WEIM */
> +		for (i = 0; i < devtype->cs_regs_count; i++)
> +			writel(value[i],
> +				base + cs_idx * devtype->cs_stride + i * 4);
> +	}
>  
>  	return 0;
>  }
> -- 
> 2.17.1
> 

Re: [PATCH v2 1/2] bus: imx-weim: support multiple address ranges per child node

[Sven Van Asbroeck]

Hello Shawn, many thanks for the patch review, I really appreciate it !

On Wed, Dec 5, 2018 at 2:52 AM Shawn Guo <shawnguo@kernel.org> wrote:
>
> On Fri, Nov 30, 2018 at 03:56:23PM -0500, thesven73@gmail.com wrote:
> > From: Sven Van Asbroeck <TheSven73@googlemail.com>
> >
> > Ensure that timing values for the child node are applied to
> > all chip selects in the child's address ranges.
> >
>
> I'm not sure about that.  Shouldn't we have another child node for
> different chip select, something like below?
>
> &weim {
>         acme@0,0 {
>                 compatible = "acme,whatever";
>                 reg = <0 0 0x100>, <0 0x400000 0x800>;
>                 fsl,weim-cs-timing = <0x024400b1 0x00001010 0x20081100
>                                       0x00000000 0xa0000240 0x00000000>;
>         };
>
>         acme@1,400000 {
>                 compatible = "acme,whatever";
>                 reg = <1 0x400000 0x800>;
>                 fsl,weim-cs-timing = <0x024400b1 0x00001010 0x20081100
>                                       0x00000000 0xa0000240 0x00000000>;
>         };
>
> Shawn

I am submitting patches for a device that spans chip selects :(
And such a device needs multiple address changes with different chip selects.

Imagine we have an acme device, which contains a control and a fifo region,
on different chip selects:

&weim {
        acme@0 {
                compatible = "acme";
                reg = <0 0x0 0x100>, <1 0x0 0x100>;
        };
};

Now in probe we can access both regions:
int acme_probe(struct platform_device *pdev)
{
        control_res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        fifo_res =    platform_get_resource(pdev, IORESOURCE_MEM, 1);
        /* all ok */
}

But, if we have two separate child nodes, we also get two calls to probe(),
which assumes two devices on the bus, and that is incorrect:

&weim {
        acme@0 {
                compatible = "acme";
                reg = <0 0x0 0x100>;
        };
        acme@1 {
                compatible = "acme";
                reg = <1 0x0 0x100>;
        };
};

int acme_probe(struct platform_device *pdev)
{
        control_res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        /* next call always fails */
        fifo_res =    platform_get_resource(pdev, IORESOURCE_MEM, 1);
}

For my patchset, Rob Herring suggested I made changes to the imx-weim driver
to accommodate multi-chipselect devices.

See the conversation below between Rob Herring and myself:
https://lkml.org/lkml/2018/11/30/390

If you are not entirely satisfied with my patch, then perhaps you
could think of another way to support multi-chipselect devices?

Many thanks,
Sven

Re: [PATCH v2 1/2] bus: imx-weim: support multiple address ranges per child node

[Shawn Guo]

On Wed, Dec 05, 2018 at 10:08:16AM -0500, Sven Van Asbroeck wrote:
> Hello Shawn, many thanks for the patch review, I really appreciate it !
> 
> On Wed, Dec 5, 2018 at 2:52 AM Shawn Guo <shawnguo@kernel.org> wrote:
> >
> > On Fri, Nov 30, 2018 at 03:56:23PM -0500, thesven73@gmail.com wrote:
> > > From: Sven Van Asbroeck <TheSven73@googlemail.com>
> > >
> > > Ensure that timing values for the child node are applied to
> > > all chip selects in the child's address ranges.
> > >
> >
> > I'm not sure about that.  Shouldn't we have another child node for
> > different chip select, something like below?
> >
> > &weim {
> >         acme@0,0 {
> >                 compatible = "acme,whatever";
> >                 reg = <0 0 0x100>, <0 0x400000 0x800>;
> >                 fsl,weim-cs-timing = <0x024400b1 0x00001010 0x20081100
> >                                       0x00000000 0xa0000240 0x00000000>;
> >         };
> >
> >         acme@1,400000 {
> >                 compatible = "acme,whatever";
> >                 reg = <1 0x400000 0x800>;
> >                 fsl,weim-cs-timing = <0x024400b1 0x00001010 0x20081100
> >                                       0x00000000 0xa0000240 0x00000000>;
> >         };
> >
> > Shawn
> 
> I am submitting patches for a device that spans chip selects :(
> And such a device needs multiple address changes with different chip selects.
> 
> Imagine we have an acme device, which contains a control and a fifo region,
> on different chip selects:
> 
> &weim {
>         acme@0 {
>                 compatible = "acme";
>                 reg = <0 0x0 0x100>, <1 0x0 0x100>;
>         };
> };
> 
> Now in probe we can access both regions:
> int acme_probe(struct platform_device *pdev)
> {
>         control_res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>         fifo_res =    platform_get_resource(pdev, IORESOURCE_MEM, 1);
>         /* all ok */
> }
> 
> But, if we have two separate child nodes, we also get two calls to probe(),
> which assumes two devices on the bus, and that is incorrect:
> 
> &weim {
>         acme@0 {
>                 compatible = "acme";
>                 reg = <0 0x0 0x100>;
>         };
>         acme@1 {
>                 compatible = "acme";
>                 reg = <1 0x0 0x100>;
>         };
> };
> 
> int acme_probe(struct platform_device *pdev)
> {
>         control_res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>         /* next call always fails */
>         fifo_res =    platform_get_resource(pdev, IORESOURCE_MEM, 1);
> }
> 
> For my patchset, Rob Herring suggested I made changes to the imx-weim driver
> to accommodate multi-chipselect devices.
> 
> See the conversation below between Rob Herring and myself:
> https://lkml.org/lkml/2018/11/30/390

Sorry, I wasn't aware of the discussion.  Now I understand the
background of the changes.  But can you please patch imx-weim bindings
doc (Documentation/devicetree/bindings/bus/imx-weim.txt) to accommodate
this new use scenario?

Shawn