[PATCH 1/4] dt-bindings: Add a clocks property to the simple-framebuffer binding

[PATCH 1/4] dt-bindings: Add a clocks property to the simple-framebuffer binding

[Hans de Goede]

A simple-framebuffer node represents a framebuffer setup by the firmware /
bootloader. Such a framebuffer may have a number of clocks in use, add a
property to communicate this to the OS.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
 Documentation/devicetree/bindings/video/simple-framebuffer.txt | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/Documentation/devicetree/bindings/video/simple-framebuffer.txt b/Documentation/devicetree/bindings/video/simple-framebuffer.txt
index 70c26f3..e75478e 100644
--- a/Documentation/devicetree/bindings/video/simple-framebuffer.txt
+++ b/Documentation/devicetree/bindings/video/simple-framebuffer.txt
@@ -14,6 +14,9 @@ Required properties:
   - r5g6b5 (16-bit pixels, d[15:11]=r, d[10:5]=g, d[4:0]=b).
   - a8b8g8r8 (32-bit pixels, d[31:24]=a, d[23:16]=b, d[15:8]=g, d[7:0]=r).
 
+Optional properties:
+- clocks : List of clocks used by the framebuffer
+
 Example:
 
 	framebuffer {
-- 
2.1.0

[PATCH 2/4] simplefb: formalize pseudo palette handling

[Hans de Goede]

From: Luc Verhaegen <libv@skynet.be>

Signed-off-by: Luc Verhaegen <libv@skynet.be>
[hdegoede@redhat.com: drop unnecessary void * cast]
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
 drivers/video/fbdev/simplefb.c | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/drivers/video/fbdev/simplefb.c b/drivers/video/fbdev/simplefb.c
index 210f3a0..ec112c1 100644
--- a/drivers/video/fbdev/simplefb.c
+++ b/drivers/video/fbdev/simplefb.c
@@ -41,6 +41,8 @@ static struct fb_var_screeninfo simplefb_var = {
 	.vmode		= FB_VMODE_NONINTERLACED,
 };
 
+#define PSEUDO_PALETTE_SIZE 16
+
 static int simplefb_setcolreg(u_int regno, u_int red, u_int green, u_int blue,
 			      u_int transp, struct fb_info *info)
 {
@@ -50,7 +52,7 @@ static int simplefb_setcolreg(u_int regno, u_int red, u_int green, u_int blue,
 	u32 cb = blue >> (16 - info->var.blue.length);
 	u32 value;
 
-	if (regno >= 16)
+	if (regno >= PSEUDO_PALETTE_SIZE)
 		return -EINVAL;
 
 	value = (cr << info->var.red.offset) |
@@ -163,11 +165,16 @@ static int simplefb_parse_pd(struct platform_device *pdev,
 	return 0;
 }
 
+struct simplefb_par {
+	u32 palette[PSEUDO_PALETTE_SIZE];
+};
+
 static int simplefb_probe(struct platform_device *pdev)
 {
 	int ret;
 	struct simplefb_params params;
 	struct fb_info *info;
+	struct simplefb_par *par;
 	struct resource *mem;
 
 	if (fb_get_options("simplefb", NULL))
@@ -188,11 +195,13 @@ static int simplefb_probe(struct platform_device *pdev)
 		return -EINVAL;
 	}
 
-	info = framebuffer_alloc(sizeof(u32) * 16, &pdev->dev);
+	info = framebuffer_alloc(sizeof(struct simplefb_par), &pdev->dev);
 	if (!info)
 		return -ENOMEM;
 	platform_set_drvdata(pdev, info);
 
+	par = info->par;
+
 	info->fix = simplefb_fix;
 	info->fix.smem_start = mem->start;
 	info->fix.smem_len = resource_size(mem);
@@ -225,7 +234,7 @@ static int simplefb_probe(struct platform_device *pdev)
 		framebuffer_release(info);
 		return -ENODEV;
 	}
-	info->pseudo_palette = (void *)(info + 1);
+	info->pseudo_palette = par->palette;
 
 	dev_info(&pdev->dev, "framebuffer at 0x%lx, 0x%x bytes, mapped to 0x%p\n",
 			     info->fix.smem_start, info->fix.smem_len,
-- 
2.1.0

[PATCH 3/4] simplefb: add goto error path to probe

[Hans de Goede]

From: Luc Verhaegen <libv@skynet.be>

Signed-off-by: Luc Verhaegen <libv@skynet.be>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
 drivers/video/fbdev/simplefb.c | 20 +++++++++++++-------
 1 file changed, 13 insertions(+), 7 deletions(-)

diff --git a/drivers/video/fbdev/simplefb.c b/drivers/video/fbdev/simplefb.c
index ec112c1..b7d5c08 100644
--- a/drivers/video/fbdev/simplefb.c
+++ b/drivers/video/fbdev/simplefb.c
@@ -220,8 +220,8 @@ static int simplefb_probe(struct platform_device *pdev)
 
 	info->apertures = alloc_apertures(1);
 	if (!info->apertures) {
-		framebuffer_release(info);
-		return -ENOMEM;
+		ret = -ENOMEM;
+		goto error_fb_release;
 	}
 	info->apertures->ranges[0].base = info->fix.smem_start;
 	info->apertures->ranges[0].size = info->fix.smem_len;
@@ -231,8 +231,8 @@ static int simplefb_probe(struct platform_device *pdev)
 	info->screen_base = ioremap_wc(info->fix.smem_start,
 				       info->fix.smem_len);
 	if (!info->screen_base) {
-		framebuffer_release(info);
-		return -ENODEV;
+		ret = -ENODEV;
+		goto error_fb_release;
 	}
 	info->pseudo_palette = par->palette;
 
@@ -247,14 +247,20 @@ static int simplefb_probe(struct platform_device *pdev)
 	ret = register_framebuffer(info);
 	if (ret < 0) {
 		dev_err(&pdev->dev, "Unable to register simplefb: %d\n", ret);
-		iounmap(info->screen_base);
-		framebuffer_release(info);
-		return ret;
+		goto error_unmap;
 	}
 
 	dev_info(&pdev->dev, "fb%d: simplefb registered!\n", info->node);
 
 	return 0;
+
+ error_unmap:
+	iounmap(info->screen_base);
+
+ error_fb_release:
+	framebuffer_release(info);
+
+	return ret;
 }
 
 static int simplefb_remove(struct platform_device *pdev)
-- 
2.1.0

[PATCH 4/4] simplefb: add clock handling code

[Hans de Goede]

From: Luc Verhaegen <libv@skynet.be>

This claims and enables clocks listed in the simple framebuffer dt node.
This is needed so that the display engine, in case the required clocks
are known by the kernel code and are described in the dt, will remain
properly enabled.

Signed-off-by: Luc Verhaegen <libv@skynet.be>
[hdegoede@redhat.com: drop dev_err on kzalloc failure]
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
 drivers/video/fbdev/simplefb.c | 100 ++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 98 insertions(+), 2 deletions(-)

diff --git a/drivers/video/fbdev/simplefb.c b/drivers/video/fbdev/simplefb.c
index b7d5c08..f329cc1 100644
--- a/drivers/video/fbdev/simplefb.c
+++ b/drivers/video/fbdev/simplefb.c
@@ -26,6 +26,7 @@
 #include <linux/module.h>
 #include <linux/platform_data/simplefb.h>
 #include <linux/platform_device.h>
+#include <linux/clk-provider.h>
 
 static struct fb_fix_screeninfo simplefb_fix = {
 	.id		= "simple",
@@ -165,8 +166,98 @@ static int simplefb_parse_pd(struct platform_device *pdev,
 	return 0;
 }
 
+/*
+ * Clock handling code.
+ *
+ * Here we handle the clocks property of our "simple-framebuffer" dt node.
+ * This is necessary so that we can make sure that any clocks needed by
+ * the display engine that the bootloader set up for us (and for which it
+ * provided a simplefb dt node), stay up, for the life of the simplefb
+ * driver.
+ *
+ * When the driver unloads, we cleanly disable, and then release the clocks.
+ */
+struct simplefb_clock {
+	struct list_head list;
+	struct clk *clock;
+};
+
+/*
+ * We only complain about errors here, no action is taken as the most likely
+ * error can only happen due to a mismatch between the bootloader which set
+ * up simplefb, and the clock definitions in the device tree. Chances are
+ * that there are no adverse effects, and if there are, a clean teardown of
+ * the fb probe will not help us much either. So just complain and carry on,
+ * and hope that the user actually gets a working fb at the end of things.
+ */
+static void
+simplefb_clocks_init(struct platform_device *pdev, struct list_head *list)
+{
+	struct device_node *np = pdev->dev.of_node;
+	int clock_count, i;
+
+	INIT_LIST_HEAD(list);
+
+	if (dev_get_platdata(&pdev->dev) || !np)
+		return;
+
+	clock_count = of_clk_get_parent_count(np);
+	for (i = 0; i < clock_count; i++) {
+		struct simplefb_clock *entry;
+		struct clk *clock = of_clk_get(np, i);
+		int ret;
+
+		if (IS_ERR(clock)) {
+			dev_err(&pdev->dev, "%s: clock %d not found: %ld\n",
+			       __func__, i, PTR_ERR(clock));
+			continue;
+		}
+
+		ret = clk_prepare_enable(clock);
+		if (ret) {
+			dev_err(&pdev->dev,
+				"%s: failed to enable clock %d: %d\n",
+			       __func__, i, ret);
+			clk_put(clock);
+			continue;
+		}
+
+		entry = kzalloc(sizeof(struct simplefb_clock), GFP_KERNEL);
+		if (!entry) {
+			clk_disable_unprepare(clock);
+			clk_put(clock);
+			continue;
+		}
+
+		entry->clock = clock;
+		/*
+		 * add to the front of the list, so we disable clocks in the
+		 * correct order.
+		 */
+		list_add(&entry->list, list);
+	}
+}
+
+static void
+simplefb_clocks_destroy(struct list_head *list)
+{
+	struct list_head *pos, *n;
+
+	list_for_each_safe(pos, n, list) {
+		struct simplefb_clock *entry +			container_of(pos, struct simplefb_clock, list);
+
+		list_del(&entry->list);
+
+		clk_disable_unprepare(entry->clock);
+		clk_put(entry->clock);
+		kfree(entry);
+	}
+}
+
 struct simplefb_par {
 	u32 palette[PSEUDO_PALETTE_SIZE];
+	struct list_head clock_list[1];
 };
 
 static int simplefb_probe(struct platform_device *pdev)
@@ -236,6 +327,8 @@ static int simplefb_probe(struct platform_device *pdev)
 	}
 	info->pseudo_palette = par->palette;
 
+	simplefb_clocks_init(pdev, par->clock_list);
+
 	dev_info(&pdev->dev, "framebuffer at 0x%lx, 0x%x bytes, mapped to 0x%p\n",
 			     info->fix.smem_start, info->fix.smem_len,
 			     info->screen_base);
@@ -247,14 +340,15 @@ static int simplefb_probe(struct platform_device *pdev)
 	ret = register_framebuffer(info);
 	if (ret < 0) {
 		dev_err(&pdev->dev, "Unable to register simplefb: %d\n", ret);
-		goto error_unmap;
+		goto error_clocks;
 	}
 
 	dev_info(&pdev->dev, "fb%d: simplefb registered!\n", info->node);
 
 	return 0;
 
- error_unmap:
+ error_clocks:
+	simplefb_clocks_destroy(par->clock_list);
 	iounmap(info->screen_base);
 
  error_fb_release:
@@ -266,8 +360,10 @@ static int simplefb_probe(struct platform_device *pdev)
 static int simplefb_remove(struct platform_device *pdev)
 {
 	struct fb_info *info = platform_get_drvdata(pdev);
+	struct simplefb_par *par = info->par;
 
 	unregister_framebuffer(info);
+	simplefb_clocks_destroy(par->clock_list);
 	framebuffer_release(info);
 
 	return 0;
-- 
2.1.0

Re: [PATCH 1/4] dt-bindings: Add a clocks property to the simple-framebuffer binding

[Mike Turquette]

On Sun, Sep 28, 2014 at 5:43 AM, Hans de Goede <hdegoede@redhat.com> wrote:
> A simple-framebuffer node represents a framebuffer setup by the firmware /
> bootloader. Such a framebuffer may have a number of clocks in use, add a
> property to communicate this to the OS.
>
> Signed-off-by: Hans de Goede <hdegoede@redhat.com>

Acked-by: Mike Turquette <mturquette@linaro.org>
or
Reviewed-by: Mike Turquette <mturquette@linaro.org>

I don't know what is the right thing with these binding definitions...

Also I have one suggestion below:

> ---
>  Documentation/devicetree/bindings/video/simple-framebuffer.txt | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/video/simple-framebuffer.txt b/Documentation/devicetree/bindings/video/simple-framebuffer.txt
> index 70c26f3..e75478e 100644
> --- a/Documentation/devicetree/bindings/video/simple-framebuffer.txt
> +++ b/Documentation/devicetree/bindings/video/simple-framebuffer.txt
> @@ -14,6 +14,9 @@ Required properties:
>    - r5g6b5 (16-bit pixels, d[15:11]=r, d[10:5]=g, d[4:0]=b).
>    - a8b8g8r8 (32-bit pixels, d[31:24]=a, d[23:16]=b, d[15:8]=g, d[7:0]=r).
>
> +Optional properties:
> +- clocks : List of clocks used by the framebuffer
> +
>  Example:
>
>         framebuffer {

It might be nice to add the clocks property to the example. Something like:

clocks = <&osc 1>, <&ref 0>;

Regards,
Mike

> --
> 2.1.0
>

Re: [PATCH 1/4] dt-bindings: Add a clocks property to the simple-framebuffer binding

[Hans de Goede]

Hi,

On 09/28/2014 08:37 PM, Mike Turquette wrote:
> On Sun, Sep 28, 2014 at 5:43 AM, Hans de Goede <hdegoede@redhat.com> wrote:
>> A simple-framebuffer node represents a framebuffer setup by the firmware /
>> bootloader. Such a framebuffer may have a number of clocks in use, add a
>> property to communicate this to the OS.
>>
>> Signed-off-by: Hans de Goede <hdegoede@redhat.com>
> 
> Acked-by: Mike Turquette <mturquette@linaro.org>
> or
> Reviewed-by: Mike Turquette <mturquette@linaro.org>
> 
> I don't know what is the right thing with these binding definitions...
> 
> Also I have one suggestion below:
> 
>> ---
>>  Documentation/devicetree/bindings/video/simple-framebuffer.txt | 3 +++
>>  1 file changed, 3 insertions(+)
>>
>> diff --git a/Documentation/devicetree/bindings/video/simple-framebuffer.txt b/Documentation/devicetree/bindings/video/simple-framebuffer.txt
>> index 70c26f3..e75478e 100644
>> --- a/Documentation/devicetree/bindings/video/simple-framebuffer.txt
>> +++ b/Documentation/devicetree/bindings/video/simple-framebuffer.txt
>> @@ -14,6 +14,9 @@ Required properties:
>>    - r5g6b5 (16-bit pixels, d[15:11]=r, d[10:5]=g, d[4:0]=b).
>>    - a8b8g8r8 (32-bit pixels, d[31:24]=a, d[23:16]=b, d[15:8]=g, d[7:0]=r).
>>
>> +Optional properties:
>> +- clocks : List of clocks used by the framebuffer
>> +
>>  Example:
>>
>>         framebuffer {
> 
> It might be nice to add the clocks property to the example. Something like:
> 
> clocks = <&osc 1>, <&ref 0>;

Given the optional nature of the clocks, I've deliberately left them out,
but if people want to I can do a v2 with a clocks property added to the example.

Regards,

Hans