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@xxxxxxxxx>
---
drivers/video/backlight/Kconfig | 12 +++
drivers/video/backlight/Makefile | 1 +
drivers/video/backlight/dwi_bl.c | 124 +++++++++++++++++++++++++++++++
3 files changed, 137 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..d4bfd74b3129
--- /dev/null
+++ b/drivers/video/backlight/dwi_bl.c
@@ -0,0 +1,124 @@
+// 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@xxxxxxxxx>
+ */
+
+#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);
+ if (IS_ERR(dwi_bl->base))
+ return PTR_ERR(dwi_bl->base);
+
+ 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@xxxxxxxxx>");
+MODULE_LICENSE("Dual MIT/GPL");
--
2.47.1
