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Subject[PATCHv4 09/10] fbdev: ssd1307fb: add backlight controls for setting the contrast
Date
The backlight class is used to create userspace handles for
setting the OLED contrast.

Signed-off-by: Thomas Niederprüm <niederp@physik.uni-kl.de>
---
drivers/video/fbdev/Kconfig | 1 +
drivers/video/fbdev/ssd1307fb.c | 58 +++++++++++++++++++++++++++++++++++++++++
2 files changed, 59 insertions(+)

diff --git a/drivers/video/fbdev/Kconfig b/drivers/video/fbdev/Kconfig
index b3dd417..da70bae 100644
--- a/drivers/video/fbdev/Kconfig
+++ b/drivers/video/fbdev/Kconfig
@@ -2478,6 +2478,7 @@ config FB_SSD1307
select FB_SYS_IMAGEBLIT
select FB_DEFERRED_IO
select PWM
+ select FB_BACKLIGHT
help
This driver implements support for the Solomon SSD1307
OLED controller over I2C.
diff --git a/drivers/video/fbdev/ssd1307fb.c b/drivers/video/fbdev/ssd1307fb.c
index 0d851f1..4ebfcaf 100644
--- a/drivers/video/fbdev/ssd1307fb.c
+++ b/drivers/video/fbdev/ssd1307fb.c
@@ -7,6 +7,7 @@
*/

#include <linux/module.h>
+#include <linux/backlight.h>
#include <linux/kernel.h>
#include <linux/i2c.h>
#include <linux/fb.h>
@@ -42,6 +43,8 @@
#define SSD1307FB_SET_COM_PINS_CONFIG 0xda
#define SSD1307FB_SET_VCOMH 0xdb

+#define MAX_CONTRAST 255
+
#define REFRASHRATE 1

static u_int refreshrate = REFRASHRATE;
@@ -431,6 +434,43 @@ static int ssd1307fb_init(struct ssd1307fb_par *par)
return 0;
}

+static int ssd1307fb_update_bl(struct backlight_device *bdev)
+{
+ struct ssd1307fb_par *par = bl_get_data(bdev);
+ int ret;
+ int brightness = bdev->props.brightness;
+
+ par->contrast = brightness;
+
+ ret = ssd1307fb_write_cmd(par->client, SSD1307FB_CONTRAST);
+ if (ret < 0)
+ return ret;
+ ret = ssd1307fb_write_cmd(par->client, par->contrast);
+ if (ret < 0)
+ return ret;
+ return 0;
+}
+
+static int ssd1307fb_get_brightness(struct backlight_device *bdev)
+{
+ struct ssd1307fb_par *par = bl_get_data(bdev);
+
+ return par->contrast;
+}
+
+static int ssd1307fb_check_fb(struct backlight_device *bdev,
+ struct fb_info *info)
+{
+ return (info->bl_dev == bdev);
+}
+
+static const struct backlight_ops ssd1307fb_bl_ops = {
+ .options = BL_CORE_SUSPENDRESUME,
+ .update_status = ssd1307fb_update_bl,
+ .get_brightness = ssd1307fb_get_brightness,
+ .check_fb = ssd1307fb_check_fb,
+};
+
static struct ssd1307fb_deviceinfo ssd1307fb_ssd1305_deviceinfo = {
.device_id = DEVID_SSD1305,
.default_vcomh = 0x34,
@@ -472,6 +512,8 @@ MODULE_DEVICE_TABLE(of, ssd1307fb_of_match);
static int ssd1307fb_probe(struct i2c_client *client,
const struct i2c_device_id *id)
{
+ struct backlight_device *bl;
+ char bl_name[12];
struct fb_info *info;
struct device_node *node = client->dev.of_node;
struct fb_deferred_io *ssd1307fb_defio;
@@ -607,10 +649,24 @@ static int ssd1307fb_probe(struct i2c_client *client,
goto panel_init_error;
}

+ snprintf(bl_name, sizeof(bl_name), "ssd1307fb%d", info->node);
+ bl = backlight_device_register(bl_name, &client->dev, par,
+ &ssd1307fb_bl_ops, NULL);
+ bl->props.brightness = contrast;
+ bl->props.max_brightness = MAX_CONTRAST;
+ info->bl_dev = bl;
+
+ if (IS_ERR(bl)) {
+ dev_err(&client->dev, "unable to register backlight device: %ld\n",
+ PTR_ERR(bl));
+ goto bl_init_error;
+ }
dev_info(&client->dev, "fb%d: %s framebuffer device registered, using %d bytes of video memory\n", info->node, info->fix.id, vmem_size);

return 0;

+bl_init_error:
+ unregister_framebuffer(info);
panel_init_error:
if (par->device_info->device_id == DEVID_SSD1307) {
pwm_disable(par->pwm);
@@ -630,6 +686,8 @@ static int ssd1307fb_remove(struct i2c_client *client)

ssd1307fb_write_cmd(par->client, SSD1307FB_DISPLAY_OFF);

+ backlight_device_unregister(info->bl_dev);
+
unregister_framebuffer(info);
if (par->device_info->device_id == DEVID_SSD1307) {
pwm_disable(par->pwm);
--
2.3.0


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