[PATCH v3 0/2] simplefb: Add regulator handling support

[PATCH v3 0/2] simplefb: Add regulator handling support

[Chen-Yu Tsai]

Hi everyone,

This is v3 of the simplefb regulator support series. This series adds
regulator claiming and enabling support for simplefb.

Changes since v3:
  - Dropped extra "if" which is always true, leftover from v1.
  - Updated commit message of patch 1

Sometimes the simplefb display output path consits of external conversion
chips and/or LCD drivers and backlights. These devices normally have
GPIOs to turn them on and/or bring them out of reset, and regulators
supplying power to them.

While the kernel does not touch unclaimed GPIOs, the regulator core
happily disables unused regulators. Thus we need simplefb to claim
and enable the regulators used throughout the display pipeline.

The binding supports any named regulator supplies under its device
node. The driver will look through its properties, and claim any
regulators by matching "*-supply", as Mark suggested.

I've not done a generic helper in the regulator core yet, instead doing
the regulator property handling in the simplefb code for now.


Patch 1 adds the regulator properties to the DT binding.

Patch 2 adds code to the simplefb driver to claim and enable regulators.


Regards
ChenYu


Chen-Yu Tsai (2):
  dt-bindings: simplefb: Support regulator supply properties
  simplefb: Claim and enable regulators

 .../bindings/video/simple-framebuffer.txt          |  13 ++-
 drivers/video/fbdev/simplefb.c                     | 120 ++++++++++++++++++++-
 2 files changed, 128 insertions(+), 5 deletions(-)

-- 
2.6.1

[PATCH v3 1/2] dt-bindings: simplefb: Support regulator supply properties

[Chen-Yu Tsai]

The physical display tied to the framebuffer may have regulators
providing power to it, such as power for LCDs or interface conversion
chips.

The number of regulators in use may vary, but the regulator supply
binding can not be a list. Instead just support any named regulator
supply properties under the device node. These should be properly
named to match the device schematics / design. The driver should
take care to go through them all.

Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Mark Brown <broonie@kernel.org>
---
 .../devicetree/bindings/video/simple-framebuffer.txt        | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/Documentation/devicetree/bindings/video/simple-framebuffer.txt b/Documentation/devicetree/bindings/video/simple-framebuffer.txt
index 4474ef6e0b95..8c9e9f515c87 100644
--- a/Documentation/devicetree/bindings/video/simple-framebuffer.txt
+++ b/Documentation/devicetree/bindings/video/simple-framebuffer.txt
@@ -47,10 +47,14 @@ Required properties:
   - 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. Clocks listed here
-           are expected to already be configured correctly. The OS must
-           ensure these clocks are not modified or disabled while the
-           simple framebuffer remains active.
+- clocks : List of clocks used by the framebuffer.
+- *-supply : Any number of regulators used by the framebuffer. These should
+	     be named according to the names in the device's design.
+
+  The above resources are expected to already be configured correctly.
+  The OS must ensure they are not modified or disabled while the simple
+  framebuffer remains active.
+
 - display : phandle pointing to the primary display hardware node
 
 Example:
@@ -68,6 +72,7 @@ chosen {
 		stride = <(1600 * 2)>;
 		format = "r5g6b5";
 		clocks = <&ahb_gates 36>, <&ahb_gates 43>, <&ahb_gates 44>;
+		lcd-supply = <&reg_dc1sw>;
 		display = <&lcdc0>;
 	};
 	stdout-path = "display0";
-- 
2.6.1

[PATCH v3 2/2] simplefb: Claim and enable regulators

[Chen-Yu Tsai]

This claims and enables regulators listed in the simple framebuffer dt
node. This is needed so that regulators powering the display pipeline
and external hardware, described in the device node and known by the
kernel code, will remain properly enabled.

Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Mark Brown <broonie@kernel.org>
---
 drivers/video/fbdev/simplefb.c | 120 ++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 119 insertions(+), 1 deletion(-)

diff --git a/drivers/video/fbdev/simplefb.c b/drivers/video/fbdev/simplefb.c
index 52c5c7e63b52..9de34ee15ac0 100644
--- a/drivers/video/fbdev/simplefb.c
+++ b/drivers/video/fbdev/simplefb.c
@@ -28,7 +28,10 @@
 #include <linux/platform_device.h>
 #include <linux/clk.h>
 #include <linux/clk-provider.h>
+#include <linux/of.h>
 #include <linux/of_platform.h>
+#include <linux/parser.h>
+#include <linux/regulator/consumer.h>
 
 static struct fb_fix_screeninfo simplefb_fix = {
 	.id		= "simple",
@@ -174,6 +177,10 @@ struct simplefb_par {
 	int clk_count;
 	struct clk **clks;
 #endif
+#if defined CONFIG_OF && defined CONFIG_REGULATOR
+	u32 regulator_count;
+	struct regulator **regulators;
+#endif
 };
 
 #if defined CONFIG_OF && defined CONFIG_COMMON_CLK
@@ -269,6 +276,110 @@ static int simplefb_clocks_init(struct simplefb_par *par,
 static void simplefb_clocks_destroy(struct simplefb_par *par) { }
 #endif
 
+#if defined CONFIG_OF && defined CONFIG_REGULATOR
+
+#define SUPPLY_SUFFIX "-supply"
+
+/*
+ * Regulator handling code.
+ *
+ * Here we handle the num-supplies and vin*-supply properties of our
+ * "simple-framebuffer" dt node. This is necessary so that we can make sure
+ * that any regulators needed by the display hardware 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
+ * regulators.
+ *
+ * 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 regulator 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 int simplefb_regulators_init(struct simplefb_par *par,
+	struct platform_device *pdev)
+{
+	struct device_node *np = pdev->dev.of_node;
+	struct property *prop;
+	struct regulator *regulator;
+	const char *p;
+	int count = 0, i = 0, ret;
+
+	if (dev_get_platdata(&pdev->dev) || !np)
+		return 0;
+
+	/* Count the number of regulator supplies */
+	for_each_property_of_node(np, prop) {
+		p = strstr(prop->name, SUPPLY_SUFFIX);
+		if (p && p != prop->name)
+			count++;
+	}
+
+	if (!count)
+		return 0;
+
+	par->regulators = devm_kcalloc(&pdev->dev, count,
+				       sizeof(struct regulator *), GFP_KERNEL);
+	if (!par->regulators)
+		return -ENOMEM;
+
+	/* Get all the regulators */
+	for_each_property_of_node(np, prop) {
+		char name[32]; /* 32 is max size of property name */
+
+		p = strstr(prop->name, SUPPLY_SUFFIX);
+		if (p && p != prop->name)
+			continue;
+
+		strlcpy(name, prop->name,
+			strlen(prop->name) - sizeof(SUPPLY_SUFFIX) + 1);
+		regulator = devm_regulator_get_optional(&pdev->dev, name);
+		if (IS_ERR(regulator)) {
+			if (PTR_ERR(regulator) = -EPROBE_DEFER)
+				return -EPROBE_DEFER;
+			dev_err(&pdev->dev, "regulator %s not found: %ld\n",
+				name, PTR_ERR(regulator));
+			continue;
+		}
+		par->regulators[i++] = regulator;
+	}
+	par->regulator_count = i;
+
+	/* Enable all the regulators */
+	for (i = 0; i < par->regulator_count; i++) {
+		ret = regulator_enable(par->regulators[i]);
+		if (ret) {
+			dev_err(&pdev->dev,
+				"failed to enable regulator %d: %d\n",
+				i, ret);
+			devm_regulator_put(par->regulators[i]);
+			par->regulators[i] = NULL;
+		}
+	}
+
+	return 0;
+}
+
+static void simplefb_regulators_destroy(struct simplefb_par *par)
+{
+	int i;
+
+	if (!par->regulators)
+		return;
+
+	for (i = 0; i < par->regulator_count; i++)
+		if (par->regulators[i])
+			regulator_disable(par->regulators[i]);
+}
+#else
+static int simplefb_regulators_init(struct simplefb_par *par,
+	struct platform_device *pdev) { return 0; }
+static void simplefb_regulators_destroy(struct simplefb_par *par) { }
+#endif
+
 static int simplefb_probe(struct platform_device *pdev)
 {
 	int ret;
@@ -340,6 +451,10 @@ static int simplefb_probe(struct platform_device *pdev)
 	if (ret < 0)
 		goto error_unmap;
 
+	ret = simplefb_regulators_init(par, pdev);
+	if (ret < 0)
+		goto error_clocks;
+
 	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);
@@ -351,13 +466,15 @@ 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_clocks;
+		goto error_regulators;
 	}
 
 	dev_info(&pdev->dev, "fb%d: simplefb registered!\n", info->node);
 
 	return 0;
 
+error_regulators:
+	simplefb_regulators_destroy(par);
 error_clocks:
 	simplefb_clocks_destroy(par);
 error_unmap:
@@ -373,6 +490,7 @@ static int simplefb_remove(struct platform_device *pdev)
 	struct simplefb_par *par = info->par;
 
 	unregister_framebuffer(info);
+	simplefb_regulators_destroy(par);
 	simplefb_clocks_destroy(par);
 	framebuffer_release(info);
 
-- 
2.6.1

Re: [PATCH v3 2/2] simplefb: Claim and enable regulators

[Chen-Yu Tsai]

On Fri, Oct 23, 2015 at 9:31 AM, Chen-Yu Tsai <wens@csie.org> wrote:
> This claims and enables regulators listed in the simple framebuffer dt
> node. This is needed so that regulators powering the display pipeline
> and external hardware, described in the device node and known by the
> kernel code, will remain properly enabled.
>
> Signed-off-by: Chen-Yu Tsai <wens@csie.org>
> Reviewed-by: Hans de Goede <hdegoede@redhat.com>
> Acked-by: Mark Brown <broonie@kernel.org>
> ---
>  drivers/video/fbdev/simplefb.c | 120 ++++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 119 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/video/fbdev/simplefb.c b/drivers/video/fbdev/simplefb.c
> index 52c5c7e63b52..9de34ee15ac0 100644
> --- a/drivers/video/fbdev/simplefb.c
> +++ b/drivers/video/fbdev/simplefb.c
> @@ -28,7 +28,10 @@
>  #include <linux/platform_device.h>
>  #include <linux/clk.h>
>  #include <linux/clk-provider.h>
> +#include <linux/of.h>
>  #include <linux/of_platform.h>
> +#include <linux/parser.h>
> +#include <linux/regulator/consumer.h>
>
>  static struct fb_fix_screeninfo simplefb_fix = {
>         .id             = "simple",
> @@ -174,6 +177,10 @@ struct simplefb_par {
>         int clk_count;
>         struct clk **clks;
>  #endif
> +#if defined CONFIG_OF && defined CONFIG_REGULATOR
> +       u32 regulator_count;
> +       struct regulator **regulators;
> +#endif
>  };
>
>  #if defined CONFIG_OF && defined CONFIG_COMMON_CLK
> @@ -269,6 +276,110 @@ static int simplefb_clocks_init(struct simplefb_par *par,
>  static void simplefb_clocks_destroy(struct simplefb_par *par) { }
>  #endif
>
> +#if defined CONFIG_OF && defined CONFIG_REGULATOR
> +
> +#define SUPPLY_SUFFIX "-supply"
> +
> +/*
> + * Regulator handling code.
> + *
> + * Here we handle the num-supplies and vin*-supply properties of our
> + * "simple-framebuffer" dt node. This is necessary so that we can make sure
> + * that any regulators needed by the display hardware 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
> + * regulators.
> + *
> + * 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 regulator 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 int simplefb_regulators_init(struct simplefb_par *par,
> +       struct platform_device *pdev)
> +{
> +       struct device_node *np = pdev->dev.of_node;
> +       struct property *prop;
> +       struct regulator *regulator;
> +       const char *p;
> +       int count = 0, i = 0, ret;
> +
> +       if (dev_get_platdata(&pdev->dev) || !np)
> +               return 0;
> +
> +       /* Count the number of regulator supplies */
> +       for_each_property_of_node(np, prop) {
> +               p = strstr(prop->name, SUPPLY_SUFFIX);
> +               if (p && p != prop->name)
> +                       count++;
> +       }
> +
> +       if (!count)
> +               return 0;
> +
> +       par->regulators = devm_kcalloc(&pdev->dev, count,
> +                                      sizeof(struct regulator *), GFP_KERNEL);
> +       if (!par->regulators)
> +               return -ENOMEM;
> +
> +       /* Get all the regulators */
> +       for_each_property_of_node(np, prop) {
> +               char name[32]; /* 32 is max size of property name */
> +
> +               p = strstr(prop->name, SUPPLY_SUFFIX);
> +               if (p && p != prop->name)

Sorry, the test is completely reversed here.

> +                       continue;
> +
> +               strlcpy(name, prop->name,
> +                       strlen(prop->name) - sizeof(SUPPLY_SUFFIX) + 1);

And string length is off by 1 due to using sizeof here.

I'll send a new version. Sorry for the noise.

ChenYu

> +               regulator = devm_regulator_get_optional(&pdev->dev, name);
> +               if (IS_ERR(regulator)) {
> +                       if (PTR_ERR(regulator) = -EPROBE_DEFER)
> +                               return -EPROBE_DEFER;
> +                       dev_err(&pdev->dev, "regulator %s not found: %ld\n",
> +                               name, PTR_ERR(regulator));
> +                       continue;
> +               }
> +               par->regulators[i++] = regulator;
> +       }
> +       par->regulator_count = i;
> +
> +       /* Enable all the regulators */
> +       for (i = 0; i < par->regulator_count; i++) {
> +               ret = regulator_enable(par->regulators[i]);
> +               if (ret) {
> +                       dev_err(&pdev->dev,
> +                               "failed to enable regulator %d: %d\n",
> +                               i, ret);
> +                       devm_regulator_put(par->regulators[i]);
> +                       par->regulators[i] = NULL;
> +               }
> +       }
> +
> +       return 0;
> +}
> +
> +static void simplefb_regulators_destroy(struct simplefb_par *par)
> +{
> +       int i;
> +
> +       if (!par->regulators)
> +               return;
> +
> +       for (i = 0; i < par->regulator_count; i++)
> +               if (par->regulators[i])
> +                       regulator_disable(par->regulators[i]);
> +}
> +#else
> +static int simplefb_regulators_init(struct simplefb_par *par,
> +       struct platform_device *pdev) { return 0; }
> +static void simplefb_regulators_destroy(struct simplefb_par *par) { }
> +#endif
> +
>  static int simplefb_probe(struct platform_device *pdev)
>  {
>         int ret;
> @@ -340,6 +451,10 @@ static int simplefb_probe(struct platform_device *pdev)
>         if (ret < 0)
>                 goto error_unmap;
>
> +       ret = simplefb_regulators_init(par, pdev);
> +       if (ret < 0)
> +               goto error_clocks;
> +
>         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);
> @@ -351,13 +466,15 @@ 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_clocks;
> +               goto error_regulators;
>         }
>
>         dev_info(&pdev->dev, "fb%d: simplefb registered!\n", info->node);
>
>         return 0;
>
> +error_regulators:
> +       simplefb_regulators_destroy(par);
>  error_clocks:
>         simplefb_clocks_destroy(par);
>  error_unmap:
> @@ -373,6 +490,7 @@ static int simplefb_remove(struct platform_device *pdev)
>         struct simplefb_par *par = info->par;
>
>         unregister_framebuffer(info);
> +       simplefb_regulators_destroy(par);
>         simplefb_clocks_destroy(par);
>         framebuffer_release(info);
>
> --
> 2.6.1
>