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From ae5ae9278768c3d096910705bfa9af85da20a8cf Mon Sep 17 00:00:00 2001
From: P33M <P33M@github.com>
Date: Wed, 21 Oct 2015 14:55:21 +0100
Subject: [PATCH] rpi_display: add backlight driver and overlay
Add a mailbox-driven backlight controller for the Raspberry Pi DSI
touchscreen display. Requires updated GPU firmware to recognise the
mailbox request.
Signed-off-by: Gordon Hollingworth <gordon@raspberrypi.org>
---
drivers/video/backlight/Kconfig | 6 ++
drivers/video/backlight/Makefile | 1 +
drivers/video/backlight/rpi_backlight.c | 119 ++++++++++++++++++++++++++++++++
3 files changed, 126 insertions(+)
create mode 100644 drivers/video/backlight/rpi_backlight.c
--- a/drivers/video/backlight/Kconfig
+++ b/drivers/video/backlight/Kconfig
@@ -265,6 +265,12 @@ config BACKLIGHT_PWM
If you have a LCD backlight adjustable by PWM, say Y to enable
this driver.
+config BACKLIGHT_RPI
+ tristate "Raspberry Pi display firmware driven backlight"
+ help
+ If you have the Raspberry Pi DSI touchscreen display, say Y to
+ enable the mailbox-controlled backlight driver.
+
config BACKLIGHT_DA903X
tristate "Backlight Driver for DA9030/DA9034 using WLED"
depends on PMIC_DA903X
--- a/drivers/video/backlight/Makefile
+++ b/drivers/video/backlight/Makefile
@@ -50,6 +50,7 @@ obj-$(CONFIG_BACKLIGHT_PANDORA) += pand
obj-$(CONFIG_BACKLIGHT_PCF50633) += pcf50633-backlight.o
obj-$(CONFIG_BACKLIGHT_PM8941_WLED) += pm8941-wled.o
obj-$(CONFIG_BACKLIGHT_PWM) += pwm_bl.o
+obj-$(CONFIG_BACKLIGHT_RPI) += rpi_backlight.o
obj-$(CONFIG_BACKLIGHT_SAHARA) += kb3886_bl.o
obj-$(CONFIG_BACKLIGHT_SKY81452) += sky81452-backlight.o
obj-$(CONFIG_BACKLIGHT_TOSA) += tosa_bl.o
--- /dev/null
+++ b/drivers/video/backlight/rpi_backlight.c
@@ -0,0 +1,119 @@
+/*
+ * rpi_bl.c - Backlight controller through VPU
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/backlight.h>
+#include <linux/err.h>
+#include <linux/fb.h>
+#include <linux/gpio.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_gpio.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <soc/bcm2835/raspberrypi-firmware.h>
+
+struct rpi_backlight {
+ struct device *dev;
+ struct device *fbdev;
+ struct rpi_firmware *fw;
+};
+
+static int rpi_backlight_update_status(struct backlight_device *bl)
+{
+ struct rpi_backlight *gbl = bl_get_data(bl);
+ int brightness = bl->props.brightness;
+ int ret;
+
+ if (bl->props.power != FB_BLANK_UNBLANK ||
+ bl->props.fb_blank != FB_BLANK_UNBLANK ||
+ bl->props.state & (BL_CORE_SUSPENDED | BL_CORE_FBBLANK))
+ brightness = 0;
+
+ ret = rpi_firmware_property(gbl->fw,
+ RPI_FIRMWARE_FRAMEBUFFER_SET_BACKLIGHT,
+ &brightness, sizeof(brightness));
+ if (ret) {
+ dev_err(gbl->dev, "Failed to set brightness\n");
+ return ret;
+ }
+
+ if (brightness < 0) {
+ dev_err(gbl->dev, "Backlight change failed\n");
+ return -EAGAIN;
+ }
+
+ return 0;
+}
+
+static const struct backlight_ops rpi_backlight_ops = {
+ .options = BL_CORE_SUSPENDRESUME,
+ .update_status = rpi_backlight_update_status,
+};
+
+static int rpi_backlight_probe(struct platform_device *pdev)
+{
+ struct backlight_properties props;
+ struct backlight_device *bl;
+ struct rpi_backlight *gbl;
+ struct device_node *fw_node;
+
+ gbl = devm_kzalloc(&pdev->dev, sizeof(*gbl), GFP_KERNEL);
+ if (gbl == NULL)
+ return -ENOMEM;
+
+ gbl->dev = &pdev->dev;
+
+ fw_node = of_parse_phandle(pdev->dev.of_node, "firmware", 0);
+ if (!fw_node) {
+ dev_err(&pdev->dev, "Missing firmware node\n");
+ return -ENOENT;
+ }
+
+ gbl->fw = rpi_firmware_get(fw_node);
+ if (!gbl->fw)
+ return -EPROBE_DEFER;
+
+ memset(&props, 0, sizeof(props));
+ props.type = BACKLIGHT_RAW;
+ props.max_brightness = 255;
+ bl = devm_backlight_device_register(&pdev->dev, dev_name(&pdev->dev),
+ &pdev->dev, gbl, &rpi_backlight_ops,
+ &props);
+ if (IS_ERR(bl)) {
+ dev_err(&pdev->dev, "failed to register backlight\n");
+ return PTR_ERR(bl);
+ }
+
+ bl->props.brightness = 255;
+ backlight_update_status(bl);
+
+ platform_set_drvdata(pdev, bl);
+ return 0;
+}
+
+static const struct of_device_id rpi_backlight_of_match[] = {
+ { .compatible = "raspberrypi,rpi-backlight" },
+ { /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, rpi_backlight_of_match);
+
+static struct platform_driver rpi_backlight_driver = {
+ .driver = {
+ .name = "rpi-backlight",
+ .of_match_table = of_match_ptr(rpi_backlight_of_match),
+ },
+ .probe = rpi_backlight_probe,
+};
+
+module_platform_driver(rpi_backlight_driver);
+
+MODULE_AUTHOR("Gordon Hollingworth <gordon@raspberrypi.org>");
+MODULE_DESCRIPTION("Raspberry Pi mailbox based Backlight Driver");
+MODULE_LICENSE("GPL");
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