This patch exposes backlight control into userspace by creating a
backlight device instead of directly accessing the PWM registers.
The backlight driver can't go on a separate file as it shares the I2C
bus & address with the panel.
Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@xxxxxxx>
---
v1 -> v2:
- Add Kconfig dependency with BACKLIGHT_CLASS_DEVICE
drivers/gpu/drm/panel/Kconfig | 1 +
.../drm/panel/panel-raspberrypi-touchscreen.c | 33 +++++++++++++++++--
2 files changed, 32 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/panel/Kconfig b/drivers/gpu/drm/panel/Kconfig
index 6020c30a33b3..1ce35483f342 100644
--- a/drivers/gpu/drm/panel/Kconfig
+++ b/drivers/gpu/drm/panel/Kconfig
@@ -112,6 +112,7 @@ config DRM_PANEL_PANASONIC_VVX10F034N00
config DRM_PANEL_RASPBERRYPI_TOUCHSCREEN
tristate "Raspberry Pi 7-inch touchscreen panel"
depends on DRM_MIPI_DSI
+ depends on BACKLIGHT_CLASS_DEVICE
help
Say Y here if you want to enable support for the Raspberry
Pi 7" Touchscreen. To compile this driver as a module,
diff --git a/drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c b/drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c
index 2c9c9722734f..838b5c8767bc 100644
--- a/drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c
+++ b/drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c
@@ -52,6 +52,7 @@
#include <linux/of_device.h>
#include <linux/of_graph.h>
#include <linux/pm.h>
+#include <linux/backlight.h>
#include <drm/drm_panel.h>
#include <drm/drmP.h>
@@ -196,6 +197,7 @@ struct rpi_touchscreen {
struct drm_panel base;
struct mipi_dsi_device *dsi;
struct i2c_client *i2c;
+ struct backlight_device *backlight;
};
static const struct drm_display_mode rpi_touchscreen_modes[] = {
@@ -256,7 +258,8 @@ static int rpi_touchscreen_disable(struct drm_panel *panel)
{
struct rpi_touchscreen *ts = panel_to_ts(panel);
- rpi_touchscreen_i2c_write(ts, REG_PWM, 0);
+ ts->backlight->props.brightness = 0;
+ backlight_update_status(ts->backlight);
rpi_touchscreen_i2c_write(ts, REG_POWERON, 0);
udelay(1);
@@ -300,7 +303,8 @@ static int rpi_touchscreen_enable(struct drm_panel *panel)
msleep(100);
/* Turn on the backlight. */
- rpi_touchscreen_i2c_write(ts, REG_PWM, 255);
+ ts->backlight->props.brightness = 255;
+ backlight_update_status(ts->backlight);
/* Default to the same orientation as the closed source
* firmware used for the panel. Runtime rotation
@@ -358,12 +362,26 @@ static const struct drm_panel_funcs rpi_touchscreen_funcs = {
.get_modes = rpi_touchscreen_get_modes,
};
+static int raspberrypi_bl_update_status(struct backlight_device *bl)
+{
+ struct rpi_touchscreen *ts = bl_get_data(bl);
+
+ rpi_touchscreen_i2c_write(ts, REG_PWM, bl->props.brightness);
+
+ return 0;
+}
+
+static const struct backlight_ops raspberrypi_bl_ops = {
+ .update_status = raspberrypi_bl_update_status,
+};
+
static int rpi_touchscreen_probe(struct i2c_client *i2c,
const struct i2c_device_id *id)
{
struct device *dev = &i2c->dev;
struct rpi_touchscreen *ts;
struct device_node *endpoint, *dsi_host_node;
+ struct backlight_properties props;
struct mipi_dsi_host *host;
int ret, ver;
struct mipi_dsi_device_info info = {
@@ -398,6 +416,17 @@ static int rpi_touchscreen_probe(struct i2c_client *i2c,
/* Turn off at boot, so we can cleanly sequence powering on. */
rpi_touchscreen_i2c_write(ts, REG_POWERON, 0);
+ memset(&props, 0, sizeof(props));
+ props.type = BACKLIGHT_RAW;
+ props.max_brightness = 255;
+ ts->backlight = devm_backlight_device_register(dev, dev_name(dev), dev,
+ ts, &raspberrypi_bl_ops,
+ &props);
+ if (IS_ERR(ts->backlight)) {
+ dev_err(dev, "Failed to create backlight device\n");
+ return PTR_ERR(ts->backlight);
+ }
+
/* Look up the DSI host. It needs to probe before we do. */
endpoint = of_graph_get_next_endpoint(dev->of_node, NULL);
dsi_host_node = of_graph_get_remote_port_parent(endpoint);
--
2.19.2
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