[PATCH v5 0/3] PWM changes for rk3288-evb

[PATCH v5 0/3] PWM changes for rk3288-evb

[Doug Anderson]

These patches enable the PWM backlight for the rk3288-evb board.
There were tested by watching the backlight grow from off to max with
the following instructions:

  cd /sys/class/backlight/backlight*/
  for i in $(seq 255); do echo $i > brightness; sleep .01; done

The first patch switches PWM cells from 2 to 3 on rk3288.  I think it
could land in Thierry's tree.  This patch will break backward
compatibility for rk3288 until changes land handling PWM cells more
dynamically, but since there are no rk3288 boards shipping yet it
seems OK.

The 2nd and 3rd patches are DTS ones.  They could land in Heiko's tree
after the first two patches.  They are based atop his current WIP 3.18
dts tree.  Note that instantiating the PWM backlight will cause the
system to hang unless Heiko's (clk: rockchip: protect critical clocks
from getting disabled) <patchwork.kernel.org/patch/4725391> is landed.

There are no compile time or runtime dependencies between these
patches except that patch #2 needs to come before patch #3.  ...and of
course the PWM won't work without all 3 patches.

There is a missing patch from this series: the patch that enables the
proper IP in the rk3288 "grf" (general register file).  That patch can
come later.  For now we'll assume that firmware (or some out of tree
kernel patch) will set it up.

Changes in v5:
- Back to version 3 (no rockchip,grf).

Changes in v4:
- Updated comment not to add caveats about pwm_cells 3.
- rockchip_pwm_set_polarity() is now static.
- Separate pwm_ops for v1 and v2; no set_polarity() in v1.
- Added a blank line.
- Add rockchip,grf to pwm nodes.

Changes in v3:
- Don't store a private copy of polarity.
- Use true instead of 1.
- Cleanup init order with "has_invert".
- Fix space to tab in 2 places in DTS.
- Make sure PWM is upper case in prose.

Doug Anderson (3):
  pwm: rockchip: Allow polarity invert on rk3288
  ARM: dts: Add main PWM info to rk3288
  ARM: dts: Enable PWM backlight on rk3288-evb

 .../devicetree/bindings/pwm/pwm-rockchip.txt       |  4 +-
 arch/arm/boot/dts/rk3288-evb.dtsi                  | 53 +++++++++++++++++
 arch/arm/boot/dts/rk3288.dtsi                      | 68 ++++++++++++++++++++++
 drivers/pwm/pwm-rockchip.c                         | 57 +++++++++++++++---
 4 files changed, 171 insertions(+), 11 deletions(-)

-- 
2.1.0.rc2.206.gedb03e5

[PATCH v5 1/3] pwm: rockchip: Allow polarity invert on rk3288

[Doug Anderson]

The rk3288 has the ability to invert the polarity of the PWM.  Let's
enable that ability.  Note that this increases pwm_cells to 3 for
rk3288.

Signed-off-by: Doug Anderson <dianders@chromium.org>
Reviewed-by: Caesar Wang <caesar.wang@rock-chips.com>
---
Changes in v5: None
Changes in v4:
- Updated comment not to add caveats about pwm_cells 3.
- rockchip_pwm_set_polarity() is now static.
- Separate pwm_ops for v1 and v2; no set_polarity() in v1.
- Added a blank line.

Changes in v3:
- Don't store a private copy of polarity.
- Use true instead of 1.
- Cleanup init order with "has_invert".

 .../devicetree/bindings/pwm/pwm-rockchip.txt       |  4 +-
 drivers/pwm/pwm-rockchip.c                         | 57 ++++++++++++++++++----
 2 files changed, 50 insertions(+), 11 deletions(-)

diff --git a/Documentation/devicetree/bindings/pwm/pwm-rockchip.txt b/Documentation/devicetree/bindings/pwm/pwm-rockchip.txt
index d47d15a..b8be3d0 100644
--- a/Documentation/devicetree/bindings/pwm/pwm-rockchip.txt
+++ b/Documentation/devicetree/bindings/pwm/pwm-rockchip.txt
@@ -7,8 +7,8 @@ Required properties:
    "rockchip,vop-pwm": found integrated in VOP on RK3288 SoC
  - reg: physical base address and length of the controller's registers
  - clocks: phandle and clock specifier of the PWM reference clock
- - #pwm-cells: should be 2. See pwm.txt in this directory for a
-   description of the cell format.
+ - #pwm-cells: must be 2 (rk2928) or 3 (rk3288). See pwm.txt in this directory
+   for a description of the cell format.
 
 Example:
 
diff --git a/drivers/pwm/pwm-rockchip.c b/drivers/pwm/pwm-rockchip.c
index bdd8644..9442df2 100644
--- a/drivers/pwm/pwm-rockchip.c
+++ b/drivers/pwm/pwm-rockchip.c
@@ -24,7 +24,9 @@
 #define PWM_ENABLE		(1 << 0)
 #define PWM_CONTINUOUS		(1 << 1)
 #define PWM_DUTY_POSITIVE	(1 << 3)
+#define PWM_DUTY_NEGATIVE	(0 << 3)
 #define PWM_INACTIVE_NEGATIVE	(0 << 4)
+#define PWM_INACTIVE_POSITIVE	(1 << 4)
 #define PWM_OUTPUT_LEFT		(0 << 5)
 #define PWM_LP_DISABLE		(0 << 8)
 
@@ -45,8 +47,10 @@ struct rockchip_pwm_regs {
 struct rockchip_pwm_data {
 	struct rockchip_pwm_regs regs;
 	unsigned int prescaler;
+	const struct pwm_ops *ops;
 
-	void (*set_enable)(struct pwm_chip *chip, bool enable);
+	void (*set_enable)(struct pwm_chip *chip,
+			   struct pwm_device *pwm, bool enable);
 };
 
 static inline struct rockchip_pwm_chip *to_rockchip_pwm_chip(struct pwm_chip *c)
@@ -54,7 +58,8 @@ static inline struct rockchip_pwm_chip *to_rockchip_pwm_chip(struct pwm_chip *c)
 	return container_of(c, struct rockchip_pwm_chip, chip);
 }
 
-static void rockchip_pwm_set_enable_v1(struct pwm_chip *chip, bool enable)
+static void rockchip_pwm_set_enable_v1(struct pwm_chip *chip,
+				       struct pwm_device *pwm, bool enable)
 {
 	struct rockchip_pwm_chip *pc = to_rockchip_pwm_chip(chip);
 	u32 enable_conf = PWM_CTRL_OUTPUT_EN | PWM_CTRL_TIMER_EN;
@@ -70,14 +75,19 @@ static void rockchip_pwm_set_enable_v1(struct pwm_chip *chip, bool enable)
 	writel_relaxed(val, pc->base + pc->data->regs.ctrl);
 }
 
-static void rockchip_pwm_set_enable_v2(struct pwm_chip *chip, bool enable)
+static void rockchip_pwm_set_enable_v2(struct pwm_chip *chip,
+				       struct pwm_device *pwm, bool enable)
 {
 	struct rockchip_pwm_chip *pc = to_rockchip_pwm_chip(chip);
 	u32 enable_conf = PWM_OUTPUT_LEFT | PWM_LP_DISABLE | PWM_ENABLE |
-			  PWM_CONTINUOUS | PWM_DUTY_POSITIVE |
-			  PWM_INACTIVE_NEGATIVE;
+			  PWM_CONTINUOUS;
 	u32 val;
 
+	if (pwm->polarity == PWM_POLARITY_INVERSED)
+		enable_conf |= PWM_DUTY_NEGATIVE | PWM_INACTIVE_POSITIVE;
+	else
+		enable_conf |= PWM_DUTY_POSITIVE | PWM_INACTIVE_NEGATIVE;
+
 	val = readl_relaxed(pc->base + pc->data->regs.ctrl);
 
 	if (enable)
@@ -124,6 +134,19 @@ static int rockchip_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
 	return 0;
 }
 
+static int rockchip_pwm_set_polarity(struct pwm_chip *chip,
+				     struct pwm_device *pwm,
+				     enum pwm_polarity polarity)
+{
+	/*
+	 * No action needed here because pwm->polarity will be set by the core
+	 * and the core will only change polarity when the PWM is not enabled.
+	 * We'll handle things in set_enable().
+	 */
+
+	return 0;
+}
+
 static int rockchip_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
 {
 	struct rockchip_pwm_chip *pc = to_rockchip_pwm_chip(chip);
@@ -133,7 +156,7 @@ static int rockchip_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
 	if (ret)
 		return ret;
 
-	pc->data->set_enable(chip, true);
+	pc->data->set_enable(chip, pwm, true);
 
 	return 0;
 }
@@ -142,18 +165,26 @@ static void rockchip_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
 {
 	struct rockchip_pwm_chip *pc = to_rockchip_pwm_chip(chip);
 
-	pc->data->set_enable(chip, false);
+	pc->data->set_enable(chip, pwm, false);
 
 	clk_disable(pc->clk);
 }
 
-static const struct pwm_ops rockchip_pwm_ops = {
+static const struct pwm_ops rockchip_pwm_ops_v1 = {
 	.config = rockchip_pwm_config,
 	.enable = rockchip_pwm_enable,
 	.disable = rockchip_pwm_disable,
 	.owner = THIS_MODULE,
 };
 
+static const struct pwm_ops rockchip_pwm_ops_v2 = {
+	.config = rockchip_pwm_config,
+	.set_polarity = rockchip_pwm_set_polarity,
+	.enable = rockchip_pwm_enable,
+	.disable = rockchip_pwm_disable,
+	.owner = THIS_MODULE,
+};
+
 static const struct rockchip_pwm_data pwm_data_v1 = {
 	.regs = {
 		.duty = 0x04,
@@ -162,6 +193,7 @@ static const struct rockchip_pwm_data pwm_data_v1 = {
 		.ctrl = 0x0c,
 	},
 	.prescaler = 2,
+	.ops = &rockchip_pwm_ops_v1,
 	.set_enable = rockchip_pwm_set_enable_v1,
 };
 
@@ -173,6 +205,7 @@ static const struct rockchip_pwm_data pwm_data_v2 = {
 		.ctrl = 0x0c,
 	},
 	.prescaler = 1,
+	.ops = &rockchip_pwm_ops_v2,
 	.set_enable = rockchip_pwm_set_enable_v2,
 };
 
@@ -184,6 +217,7 @@ static const struct rockchip_pwm_data pwm_data_vop = {
 		.ctrl = 0x00,
 	},
 	.prescaler = 1,
+	.ops = &rockchip_pwm_ops_v2,
 	.set_enable = rockchip_pwm_set_enable_v2,
 };
 
@@ -227,10 +261,15 @@ static int rockchip_pwm_probe(struct platform_device *pdev)
 
 	pc->data = id->data;
 	pc->chip.dev = &pdev->dev;
-	pc->chip.ops = &rockchip_pwm_ops;
+	pc->chip.ops = pc->data->ops;
 	pc->chip.base = -1;
 	pc->chip.npwm = 1;
 
+	if (pc->data->ops->set_polarity) {
+		pc->chip.of_xlate = of_pwm_xlate_with_flags;
+		pc->chip.of_pwm_n_cells = 3;
+	}
+
 	ret = pwmchip_add(&pc->chip);
 	if (ret < 0) {
 		clk_unprepare(pc->clk);
-- 
2.1.0.rc2.206.gedb03e5

Re: [PATCH v5 1/3] pwm: rockchip: Allow polarity invert on rk3288

[Thierry Reding]

[-- Attachment #1: Type: text/plain, Size: 949 bytes --]

On Mon, Aug 25, 2014 at 03:59:25PM -0700, Doug Anderson wrote:
> The rk3288 has the ability to invert the polarity of the PWM.  Let's
> enable that ability.  Note that this increases pwm_cells to 3 for
> rk3288.
> 
> Signed-off-by: Doug Anderson <dianders@chromium.org>
> Reviewed-by: Caesar Wang <caesar.wang@rock-chips.com>
> ---
> Changes in v5: None
> Changes in v4:
> - Updated comment not to add caveats about pwm_cells 3.
> - rockchip_pwm_set_polarity() is now static.
> - Separate pwm_ops for v1 and v2; no set_polarity() in v1.
> - Added a blank line.
> 
> Changes in v3:
> - Don't store a private copy of polarity.
> - Use true instead of 1.
> - Cleanup init order with "has_invert".
> 
>  .../devicetree/bindings/pwm/pwm-rockchip.txt       |  4 +-
>  drivers/pwm/pwm-rockchip.c                         | 57 ++++++++++++++++++----
>  2 files changed, 50 insertions(+), 11 deletions(-)

Applied, thanks.

Thierry

[-- Attachment #2: Type: application/pgp-signature, Size: 819 bytes --]

[PATCH v5 2/3] ARM: dts: Add main PWM info to rk3288

[Doug Anderson]

This adds the PWM info (other than the VOP PWM) to the main rk3288
dtsi file.

Signed-off-by: Caesar Wang <caesar.wang@rock-chips.com>
Signed-off-by: Doug Anderson <dianders@chromium.org>
---
Changes in v5:
- Back to version 3 (no rockchip,grf).

Changes in v4:
- Add rockchip,grf to pwm nodes.

Changes in v3: None

 arch/arm/boot/dts/rk3288.dtsi | 68 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 68 insertions(+)

diff --git a/arch/arm/boot/dts/rk3288.dtsi b/arch/arm/boot/dts/rk3288.dtsi
index 36be7bb..9c9d9c5 100644
--- a/arch/arm/boot/dts/rk3288.dtsi
+++ b/arch/arm/boot/dts/rk3288.dtsi
@@ -261,6 +261,50 @@
 		status = "disabled";
 	};
 
+	pwm0: pwm@ff680000 {
+		compatible = "rockchip,rk3288-pwm";
+		reg = <0xff680000 0x10>;
+		#pwm-cells = <3>;
+		pinctrl-names = "default";
+		pinctrl-0 = <&pwm0_pin>;
+		clocks = <&cru PCLK_PWM>;
+		clock-names = "pwm";
+		status = "disabled";
+	};
+
+	pwm1: pwm@ff680010 {
+		compatible = "rockchip,rk3288-pwm";
+		reg = <0xff680010 0x10>;
+		#pwm-cells = <3>;
+		pinctrl-names = "default";
+		pinctrl-0 = <&pwm1_pin>;
+		clocks = <&cru PCLK_PWM>;
+		clock-names = "pwm";
+		status = "disabled";
+	};
+
+	pwm2: pwm@ff680020 {
+		compatible = "rockchip,rk3288-pwm";
+		reg = <0xff680020 0x10>;
+		#pwm-cells = <3>;
+		pinctrl-names = "default";
+		pinctrl-0 = <&pwm2_pin>;
+		clocks = <&cru PCLK_PWM>;
+		clock-names = "pwm";
+		status = "disabled";
+	};
+
+	pwm3: pwm@ff680030 {
+		compatible = "rockchip,rk3288-pwm";
+		reg = <0xff680030 0x10>;
+		#pwm-cells = <2>;
+		pinctrl-names = "default";
+		pinctrl-0 = <&pwm3_pin>;
+		clocks = <&cru PCLK_PWM>;
+		clock-names = "pwm";
+		status = "disabled";
+	};
+
 	pmu: power-management@ff730000 {
 		compatible = "rockchip,rk3288-pmu", "syscon";
 		reg = <0xff730000 0x100>;
@@ -611,5 +655,29 @@
 				rockchip,pins = <5 15 3 &pcfg_pull_none>;
 			};
 		};
+
+		pwm0 {
+			pwm0_pin: pwm0-pin {
+				rockchip,pins = <7 0 RK_FUNC_1 &pcfg_pull_none>;
+			};
+		};
+
+		pwm1 {
+			pwm1_pin: pwm1-pin {
+				rockchip,pins = <7 1 RK_FUNC_1 &pcfg_pull_none>;
+			};
+		};
+
+		pwm2 {
+			pwm2_pin: pwm2-pin {
+				rockchip,pins = <7 22 RK_FUNC_3 &pcfg_pull_none>;
+			};
+		};
+
+		pwm3 {
+			pwm3_pin: pwm3-pin {
+				rockchip,pins = <7 23 RK_FUNC_3 &pcfg_pull_none>;
+			};
+		};
 	};
 };
-- 
2.1.0.rc2.206.gedb03e5

Re: [PATCH v5 2/3] ARM: dts: Add main PWM info to rk3288

[Heiko Stübner]

Am Montag, 25. August 2014, 15:59:26 schrieb Doug Anderson:
> This adds the PWM info (other than the VOP PWM) to the main rk3288
> dtsi file.
> 
> Signed-off-by: Caesar Wang <caesar.wang@rock-chips.com>
> Signed-off-by: Doug Anderson <dianders@chromium.org>
> ---

Applied to my v3.18-next/dts branch.

I've changed the RK_FUNC_3 to its numerical equivalent for now, as the pinctrl 
binding change is probably going through the pinctrl tree at some point.


> Changes in v5:
> - Back to version 3 (no rockchip,grf).
> 
> Changes in v4:
> - Add rockchip,grf to pwm nodes.
> 
> Changes in v3: None
> 
>  arch/arm/boot/dts/rk3288.dtsi | 68
> +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 68
> insertions(+)
> 
> diff --git a/arch/arm/boot/dts/rk3288.dtsi b/arch/arm/boot/dts/rk3288.dtsi
> index 36be7bb..9c9d9c5 100644
> --- a/arch/arm/boot/dts/rk3288.dtsi
> +++ b/arch/arm/boot/dts/rk3288.dtsi
> @@ -261,6 +261,50 @@
>  		status = "disabled";
>  	};
> 
> +	pwm0: pwm@ff680000 {
> +		compatible = "rockchip,rk3288-pwm";
> +		reg = <0xff680000 0x10>;
> +		#pwm-cells = <3>;
> +		pinctrl-names = "default";
> +		pinctrl-0 = <&pwm0_pin>;
> +		clocks = <&cru PCLK_PWM>;
> +		clock-names = "pwm";
> +		status = "disabled";
> +	};
> +
> +	pwm1: pwm@ff680010 {
> +		compatible = "rockchip,rk3288-pwm";
> +		reg = <0xff680010 0x10>;
> +		#pwm-cells = <3>;
> +		pinctrl-names = "default";
> +		pinctrl-0 = <&pwm1_pin>;
> +		clocks = <&cru PCLK_PWM>;
> +		clock-names = "pwm";
> +		status = "disabled";
> +	};
> +
> +	pwm2: pwm@ff680020 {
> +		compatible = "rockchip,rk3288-pwm";
> +		reg = <0xff680020 0x10>;
> +		#pwm-cells = <3>;
> +		pinctrl-names = "default";
> +		pinctrl-0 = <&pwm2_pin>;
> +		clocks = <&cru PCLK_PWM>;
> +		clock-names = "pwm";
> +		status = "disabled";
> +	};
> +
> +	pwm3: pwm@ff680030 {
> +		compatible = "rockchip,rk3288-pwm";
> +		reg = <0xff680030 0x10>;
> +		#pwm-cells = <2>;
> +		pinctrl-names = "default";
> +		pinctrl-0 = <&pwm3_pin>;
> +		clocks = <&cru PCLK_PWM>;
> +		clock-names = "pwm";
> +		status = "disabled";
> +	};
> +
>  	pmu: power-management@ff730000 {
>  		compatible = "rockchip,rk3288-pmu", "syscon";
>  		reg = <0xff730000 0x100>;
> @@ -611,5 +655,29 @@
>  				rockchip,pins = <5 15 3 &pcfg_pull_none>;
>  			};
>  		};
> +
> +		pwm0 {
> +			pwm0_pin: pwm0-pin {
> +				rockchip,pins = <7 0 RK_FUNC_1 &pcfg_pull_none>;
> +			};
> +		};
> +
> +		pwm1 {
> +			pwm1_pin: pwm1-pin {
> +				rockchip,pins = <7 1 RK_FUNC_1 &pcfg_pull_none>;
> +			};
> +		};
> +
> +		pwm2 {
> +			pwm2_pin: pwm2-pin {
> +				rockchip,pins = <7 22 RK_FUNC_3 &pcfg_pull_none>;
> +			};
> +		};
> +
> +		pwm3 {
> +			pwm3_pin: pwm3-pin {
> +				rockchip,pins = <7 23 RK_FUNC_3 &pcfg_pull_none>;
> +			};
> +		};
>  	};
>  };

[PATCH v5 3/3] ARM: dts: Enable PWM backlight on rk3288-evb

[Doug Anderson]

PWM0 is the PWM associated with the LCD backlight.  Enable it.

Signed-off-by: Doug Anderson <dianders@chromium.org>
---
Changes in v5: None
Changes in v4: None
Changes in v3:
- Fix space to tab in 2 places in DTS.
- Make sure PWM is upper case in prose.

 arch/arm/boot/dts/rk3288-evb.dtsi | 53 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 53 insertions(+)

diff --git a/arch/arm/boot/dts/rk3288-evb.dtsi b/arch/arm/boot/dts/rk3288-evb.dtsi
index 2964370..98b69d0 100644
--- a/arch/arm/boot/dts/rk3288-evb.dtsi
+++ b/arch/arm/boot/dts/rk3288-evb.dtsi
@@ -10,6 +10,7 @@
  * GNU General Public License for more details.
  */
 
+#include <dt-bindings/pwm/pwm.h>
 #include "rk3288.dtsi"
 
 / {
@@ -17,6 +18,48 @@
 		reg = <0x0 0x80000000>;
 	};
 
+	backlight {
+		compatible = "pwm-backlight";
+		brightness-levels = <
+			  0   1   2   3   4   5   6   7
+			  8   9  10  11  12  13  14  15
+			 16  17  18  19  20  21  22  23
+			 24  25  26  27  28  29  30  31
+			 32  33  34  35  36  37  38  39
+			 40  41  42  43  44  45  46  47
+			 48  49  50  51  52  53  54  55
+			 56  57  58  59  60  61  62  63
+			 64  65  66  67  68  69  70  71
+			 72  73  74  75  76  77  78  79
+			 80  81  82  83  84  85  86  87
+			 88  89  90  91  92  93  94  95
+			 96  97  98  99 100 101 102 103
+			104 105 106 107 108 109 110 111
+			112 113 114 115 116 117 118 119
+			120 121 122 123 124 125 126 127
+			128 129 130 131 132 133 134 135
+			136 137 138 139 140 141 142 143
+			144 145 146 147 148 149 150 151
+			152 153 154 155 156 157 158 159
+			160 161 162 163 164 165 166 167
+			168 169 170 171 172 173 174 175
+			176 177 178 179 180 181 182 183
+			184 185 186 187 188 189 190 191
+			192 193 194 195 196 197 198 199
+			200 201 202 203 204 205 206 207
+			208 209 210 211 212 213 214 215
+			216 217 218 219 220 221 222 223
+			224 225 226 227 228 229 230 231
+			232 233 234 235 236 237 238 239
+			240 241 242 243 244 245 246 247
+			248 249 250 251 252 253 254 255>;
+		default-brightness-level = <128>;
+		enable-gpios = <&gpio7 2 GPIO_ACTIVE_HIGH>;
+		pinctrl-names = "default";
+		pinctrl-0 = <&bl_en>;
+		pwms = <&pwm0 0 1000000 PWM_POLARITY_INVERTED>;
+	};
+
 	gpio-keys {
 		compatible = "gpio-keys";
 		#address-cells = <1>;
@@ -81,6 +124,10 @@
 	status = "okay";
 };
 
+&pwm0 {
+	status = "okay";
+};
+
 &uart0 {
 	status = "okay";
 };
@@ -102,6 +149,12 @@
 };
 
 &pinctrl {
+	backlight {
+		bl_en: bl-en {
+			rockchip,pins = <7 2 RK_FUNC_GPIO &pcfg_pull_none>;
+		};
+	};
+
 	buttons {
 		pwrbtn: pwrbtn {
 			rockchip,pins = <0 5 RK_FUNC_GPIO &pcfg_pull_up>;
-- 
2.1.0.rc2.206.gedb03e5

Re: [PATCH v5 3/3] ARM: dts: Enable PWM backlight on rk3288-evb

[Heiko Stübner]

Am Montag, 25. August 2014, 15:59:27 schrieb Doug Anderson:
> PWM0 is the PWM associated with the LCD backlight.  Enable it.
> 
> Signed-off-by: Doug Anderson <dianders@chromium.org>

Applied to my v3.18-next/dts branch.


> ---
> Changes in v5: None
> Changes in v4: None
> Changes in v3:
> - Fix space to tab in 2 places in DTS.
> - Make sure PWM is upper case in prose.
> 
>  arch/arm/boot/dts/rk3288-evb.dtsi | 53
> +++++++++++++++++++++++++++++++++++++++ 1 file changed, 53 insertions(+)
> 
> diff --git a/arch/arm/boot/dts/rk3288-evb.dtsi
> b/arch/arm/boot/dts/rk3288-evb.dtsi index 2964370..98b69d0 100644
> --- a/arch/arm/boot/dts/rk3288-evb.dtsi
> +++ b/arch/arm/boot/dts/rk3288-evb.dtsi
> @@ -10,6 +10,7 @@
>   * GNU General Public License for more details.
>   */
> 
> +#include <dt-bindings/pwm/pwm.h>
>  #include "rk3288.dtsi"
> 
>  / {
> @@ -17,6 +18,48 @@
>  		reg = <0x0 0x80000000>;
>  	};
> 
> +	backlight {
> +		compatible = "pwm-backlight";
> +		brightness-levels = <
> +			  0   1   2   3   4   5   6   7
> +			  8   9  10  11  12  13  14  15
> +			 16  17  18  19  20  21  22  23
> +			 24  25  26  27  28  29  30  31
> +			 32  33  34  35  36  37  38  39
> +			 40  41  42  43  44  45  46  47
> +			 48  49  50  51  52  53  54  55
> +			 56  57  58  59  60  61  62  63
> +			 64  65  66  67  68  69  70  71
> +			 72  73  74  75  76  77  78  79
> +			 80  81  82  83  84  85  86  87
> +			 88  89  90  91  92  93  94  95
> +			 96  97  98  99 100 101 102 103
> +			104 105 106 107 108 109 110 111
> +			112 113 114 115 116 117 118 119
> +			120 121 122 123 124 125 126 127
> +			128 129 130 131 132 133 134 135
> +			136 137 138 139 140 141 142 143
> +			144 145 146 147 148 149 150 151
> +			152 153 154 155 156 157 158 159
> +			160 161 162 163 164 165 166 167
> +			168 169 170 171 172 173 174 175
> +			176 177 178 179 180 181 182 183
> +			184 185 186 187 188 189 190 191
> +			192 193 194 195 196 197 198 199
> +			200 201 202 203 204 205 206 207
> +			208 209 210 211 212 213 214 215
> +			216 217 218 219 220 221 222 223
> +			224 225 226 227 228 229 230 231
> +			232 233 234 235 236 237 238 239
> +			240 241 242 243 244 245 246 247
> +			248 249 250 251 252 253 254 255>;
> +		default-brightness-level = <128>;
> +		enable-gpios = <&gpio7 2 GPIO_ACTIVE_HIGH>;
> +		pinctrl-names = "default";
> +		pinctrl-0 = <&bl_en>;
> +		pwms = <&pwm0 0 1000000 PWM_POLARITY_INVERTED>;
> +	};
> +
>  	gpio-keys {
>  		compatible = "gpio-keys";
>  		#address-cells = <1>;
> @@ -81,6 +124,10 @@
>  	status = "okay";
>  };
> 
> +&pwm0 {
> +	status = "okay";
> +};
> +
>  &uart0 {
>  	status = "okay";
>  };
> @@ -102,6 +149,12 @@
>  };
> 
>  &pinctrl {
> +	backlight {
> +		bl_en: bl-en {
> +			rockchip,pins = <7 2 RK_FUNC_GPIO &pcfg_pull_none>;
> +		};
> +	};
> +
>  	buttons {
>  		pwrbtn: pwrbtn {
>  			rockchip,pins = <0 5 RK_FUNC_GPIO &pcfg_pull_up>;