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[PATCH 2/3] backlight: dwi_bl: Add Apple DWI backlight driver

Nick Chan posted 3 patches 1 year ago
There is a newer version of this series
[PATCH 2/3] backlight: dwi_bl: Add Apple DWI backlight driver
Posted by Nick Chan 1 year ago 
Add driver for backlight controllers attached via Apple DWI 2-wire
interface, which is found on some Apple iPhones, iPads and iPod touches
with a LCD display.

Signed-off-by: Nick Chan <towinchenmi@gmail.com>
---
 drivers/video/backlight/Kconfig  |  12 +++
 drivers/video/backlight/Makefile |   1 +
 drivers/video/backlight/dwi_bl.c | 123 +++++++++++++++++++++++++++++++
 3 files changed, 136 insertions(+)
 create mode 100644 drivers/video/backlight/dwi_bl.c

diff --git a/drivers/video/backlight/Kconfig b/drivers/video/backlight/Kconfig
index 3614a5d29c71..e64cc3d51ac5 100644
--- a/drivers/video/backlight/Kconfig
+++ b/drivers/video/backlight/Kconfig
@@ -166,6 +166,18 @@ config BACKLIGHT_EP93XX
 	  To compile this driver as a module, choose M here: the module will
 	  be called ep93xx_bl.
 
+config BACKLIGHT_APPLE_DWI
+	tristate "Apple DWI 2-Wire Interface Backlight Driver"
+	depends on ARCH_APPLE || COMPILE_TEST
+	default y
+	help
+          Say Y to enable the backlight driver for backlight controllers
+          attached via the Apple DWI 2-wire interface which is found in some
+          Apple iPhones, iPads and iPod touches.
+
+	  To compile this driver as a module, choose M here: the module will
+	  be called dwi_bl.
+
 config BACKLIGHT_IPAQ_MICRO
 	tristate "iPAQ microcontroller backlight driver"
 	depends on MFD_IPAQ_MICRO
diff --git a/drivers/video/backlight/Makefile b/drivers/video/backlight/Makefile
index 8fc98f760a8a..0a569d7f0210 100644
--- a/drivers/video/backlight/Makefile
+++ b/drivers/video/backlight/Makefile
@@ -28,6 +28,7 @@ obj-$(CONFIG_BACKLIGHT_BD6107)		+= bd6107.o
 obj-$(CONFIG_BACKLIGHT_CLASS_DEVICE)	+= backlight.o
 obj-$(CONFIG_BACKLIGHT_DA903X)		+= da903x_bl.o
 obj-$(CONFIG_BACKLIGHT_DA9052)		+= da9052_bl.o
+obj-$(CONFIG_BACKLIGHT_APPLE_DWI)	+= dwi_bl.o
 obj-$(CONFIG_BACKLIGHT_EP93XX)		+= ep93xx_bl.o
 obj-$(CONFIG_BACKLIGHT_GPIO)		+= gpio_backlight.o
 obj-$(CONFIG_BACKLIGHT_HP680)		+= hp680_bl.o
diff --git a/drivers/video/backlight/dwi_bl.c b/drivers/video/backlight/dwi_bl.c
new file mode 100644
index 000000000000..6dd7edf661fd
--- /dev/null
+++ b/drivers/video/backlight/dwi_bl.c
@@ -0,0 +1,123 @@
+// SPDX-License-Identifier: GPL-2.0 OR MIT
+/*
+ * Driver for backlight controllers attached via Apple DWI 2-wire interface
+ *
+ * Copyright (c) 2024 Nick Chan <towinchenmi@gmail.com>
+ */
+
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/io.h>
+#include <linux/backlight.h>
+
+#define DWI_BL_CTL			0x0
+#define DWI_BL_CTL_SEND1		BIT(0)
+#define DWI_BL_CTL_SEND2		BIT(4)
+#define DWI_BL_CTL_SEND3		BIT(5)
+#define DWI_BL_CTL_LE_DATA		BIT(6)
+/* Only used on Apple A9 and later */
+#define DWI_BL_CTL_SEND4		BIT(12)
+
+#define DWI_BL_CMD			0x4
+#define DWI_BL_CMD_TYPE			GENMASK(31, 28)
+#define DWI_BL_CMD_TYPE_SET_BRIGHTNESS	0xa
+#define DWI_BL_CMD_DATA			GENMASK(10, 0)
+
+#define DWI_BL_CTL_SEND			(DWI_BL_CTL_SEND1 | \
+					 DWI_BL_CTL_SEND2 | \
+					 DWI_BL_CTL_SEND3 | \
+					 DWI_BL_CTL_LE_DATA | \
+					 DWI_BL_CTL_SEND4)
+
+#define DWI_BL_MAX_BRIGHTNESS		2047
+
+struct apple_dwi_bl {
+	void __iomem *base;
+};
+
+static int dwi_bl_update_status(struct backlight_device *bl)
+{
+	struct apple_dwi_bl *dwi_bl = bl_get_data(bl);
+
+	int brightness = backlight_get_brightness(bl);
+
+	u32 cmd = 0;
+
+	cmd |= FIELD_PREP(DWI_BL_CMD_DATA, brightness);
+	cmd |= FIELD_PREP(DWI_BL_CMD_TYPE, DWI_BL_CMD_TYPE_SET_BRIGHTNESS);
+
+	writel(cmd, dwi_bl->base + DWI_BL_CMD);
+	writel(DWI_BL_CTL_SEND, dwi_bl->base + DWI_BL_CTL);
+
+	return 0;
+}
+
+static int dwi_bl_get_brightness(struct backlight_device *bl)
+{
+	struct apple_dwi_bl *dwi_bl = bl_get_data(bl);
+
+	u32 cmd = readl(dwi_bl->base + DWI_BL_CMD);
+
+	return FIELD_GET(DWI_BL_CMD_DATA, cmd);
+}
+
+static const struct backlight_ops dwi_bl_ops = {
+	.options = BL_CORE_SUSPENDRESUME,
+	.get_brightness = dwi_bl_get_brightness,
+	.update_status	= dwi_bl_update_status
+};
+
+static int dwi_bl_probe(struct platform_device *dev)
+{
+	struct apple_dwi_bl *dwi_bl;
+	struct backlight_device *bl;
+	struct backlight_properties props;
+	struct resource *res;
+
+	dwi_bl = devm_kzalloc(&dev->dev, sizeof(struct apple_dwi_bl), GFP_KERNEL);
+	if (!dwi_bl)
+		return -ENOMEM;
+
+	res = platform_get_resource(dev, IORESOURCE_MEM, 0);
+	if (!res)
+		return -ENXIO;
+
+	dwi_bl->base = devm_ioremap_resource(&dev->dev, res);
+
+	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_RAW;
+	props.max_brightness = DWI_BL_MAX_BRIGHTNESS;
+
+	bl = devm_backlight_device_register(&dev->dev, dev->name, &dev->dev,
+					dwi_bl, &dwi_bl_ops, &props);
+
+	if (IS_ERR(bl))
+		return PTR_ERR(bl);
+
+	platform_set_drvdata(dev, dwi_bl);
+
+	bl->props.brightness = dwi_bl_get_brightness(bl);
+
+	return 0;
+}
+
+static const struct of_device_id dwi_bl_of_match[] = {
+	{ .compatible = "apple,dwi-bl" },
+	{},
+};
+
+MODULE_DEVICE_TABLE(of, dwi_bl_of_match);
+
+static struct platform_driver dwi_bl_driver = {
+	.driver		= {
+		.name	= "dwi-bl",
+		.of_match_table = dwi_bl_of_match
+	},
+	.probe		= dwi_bl_probe,
+};
+
+module_platform_driver(dwi_bl_driver);
+
+MODULE_DESCRIPTION("Apple DWI Backlight Driver");
+MODULE_AUTHOR("Nick Chan <towinchenmi@gmail.com>");
+MODULE_LICENSE("Dual MIT/GPL");
-- 
2.47.1
Re: [PATCH 2/3] backlight: dwi_bl: Add Apple DWI backlight driver
Posted by kernel test robot 1 year ago 
Hi Nick,

kernel test robot noticed the following build errors:

[auto build test ERROR on 40384c840ea1944d7c5a392e8975ed088ecf0b37]

url:    https://github.com/intel-lab-lkp/linux/commits/Nick-Chan/dt-bindings-leds-backlight-apple-dwi-bl-Add-bindings-for-Apple-DWI-backlight/20241207-013254
base:   40384c840ea1944d7c5a392e8975ed088ecf0b37
patch link:    https://lore.kernel.org/r/20241206172735.4310-3-towinchenmi%40gmail.com
patch subject: [PATCH 2/3] backlight: dwi_bl: Add Apple DWI backlight driver
config: hexagon-randconfig-001-20241207 (https://download.01.org/0day-ci/archive/20241207/202412070752.4Q1AOuGo-lkp@intel.com/config)
compiler: clang version 14.0.6 (https://github.com/llvm/llvm-project f28c006a5895fc0e329fe15fead81e37457cb1d1)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20241207/202412070752.4Q1AOuGo-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202412070752.4Q1AOuGo-lkp@intel.com/

All errors (new ones prefixed by >>):

>> drivers/video/backlight/dwi_bl.c:46:9: error: implicit declaration of function 'FIELD_PREP' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
           cmd |= FIELD_PREP(DWI_BL_CMD_DATA, brightness);
                  ^
>> drivers/video/backlight/dwi_bl.c:61:9: error: implicit declaration of function 'FIELD_GET' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
           return FIELD_GET(DWI_BL_CMD_DATA, cmd);
                  ^
   2 errors generated.


vim +/FIELD_PREP +46 drivers/video/backlight/dwi_bl.c

    37	
    38	static int dwi_bl_update_status(struct backlight_device *bl)
    39	{
    40		struct apple_dwi_bl *dwi_bl = bl_get_data(bl);
    41	
    42		int brightness = backlight_get_brightness(bl);
    43	
    44		u32 cmd = 0;
    45	
  > 46		cmd |= FIELD_PREP(DWI_BL_CMD_DATA, brightness);
    47		cmd |= FIELD_PREP(DWI_BL_CMD_TYPE, DWI_BL_CMD_TYPE_SET_BRIGHTNESS);
    48	
    49		writel(cmd, dwi_bl->base + DWI_BL_CMD);
    50		writel(DWI_BL_CTL_SEND, dwi_bl->base + DWI_BL_CTL);
    51	
    52		return 0;
    53	}
    54	
    55	static int dwi_bl_get_brightness(struct backlight_device *bl)
    56	{
    57		struct apple_dwi_bl *dwi_bl = bl_get_data(bl);
    58	
    59		u32 cmd = readl(dwi_bl->base + DWI_BL_CMD);
    60	
  > 61		return FIELD_GET(DWI_BL_CMD_DATA, cmd);
    62	}
    63	

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki
Re: [PATCH 2/3] backlight: dwi_bl: Add Apple DWI backlight driver
Posted by kernel test robot 1 year ago 
Hi Nick,

kernel test robot noticed the following build errors:

[auto build test ERROR on 40384c840ea1944d7c5a392e8975ed088ecf0b37]

url:    https://github.com/intel-lab-lkp/linux/commits/Nick-Chan/dt-bindings-leds-backlight-apple-dwi-bl-Add-bindings-for-Apple-DWI-backlight/20241207-013254
base:   40384c840ea1944d7c5a392e8975ed088ecf0b37
patch link:    https://lore.kernel.org/r/20241206172735.4310-3-towinchenmi%40gmail.com
patch subject: [PATCH 2/3] backlight: dwi_bl: Add Apple DWI backlight driver
config: arc-randconfig-001-20241207 (https://download.01.org/0day-ci/archive/20241207/202412070721.9tZI9Ogl-lkp@intel.com/config)
compiler: arceb-elf-gcc (GCC) 13.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20241207/202412070721.9tZI9Ogl-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202412070721.9tZI9Ogl-lkp@intel.com/

All errors (new ones prefixed by >>):

   drivers/video/backlight/dwi_bl.c: In function 'dwi_bl_update_status':
>> drivers/video/backlight/dwi_bl.c:46:16: error: implicit declaration of function 'FIELD_PREP' [-Werror=implicit-function-declaration]
      46 |         cmd |= FIELD_PREP(DWI_BL_CMD_DATA, brightness);
         |                ^~~~~~~~~~
   drivers/video/backlight/dwi_bl.c: In function 'dwi_bl_get_brightness':
>> drivers/video/backlight/dwi_bl.c:61:16: error: implicit declaration of function 'FIELD_GET' [-Werror=implicit-function-declaration]
      61 |         return FIELD_GET(DWI_BL_CMD_DATA, cmd);
         |                ^~~~~~~~~
   cc1: some warnings being treated as errors


vim +/FIELD_PREP +46 drivers/video/backlight/dwi_bl.c

    37	
    38	static int dwi_bl_update_status(struct backlight_device *bl)
    39	{
    40		struct apple_dwi_bl *dwi_bl = bl_get_data(bl);
    41	
    42		int brightness = backlight_get_brightness(bl);
    43	
    44		u32 cmd = 0;
    45	
  > 46		cmd |= FIELD_PREP(DWI_BL_CMD_DATA, brightness);
    47		cmd |= FIELD_PREP(DWI_BL_CMD_TYPE, DWI_BL_CMD_TYPE_SET_BRIGHTNESS);
    48	
    49		writel(cmd, dwi_bl->base + DWI_BL_CMD);
    50		writel(DWI_BL_CTL_SEND, dwi_bl->base + DWI_BL_CTL);
    51	
    52		return 0;
    53	}
    54	
    55	static int dwi_bl_get_brightness(struct backlight_device *bl)
    56	{
    57		struct apple_dwi_bl *dwi_bl = bl_get_data(bl);
    58	
    59		u32 cmd = readl(dwi_bl->base + DWI_BL_CMD);
    60	
  > 61		return FIELD_GET(DWI_BL_CMD_DATA, cmd);
    62	}
    63	

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki

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