Re: [PATCH v6 19/19] auxdisplay: ht16k33: Add LED support
From: Robin van der Gracht
Date: Thu Sep 30 2021 - 06:57:17 EST
Hi Geert,
On 2021-09-14 16:38, Geert Uytterhoeven wrote:
Instantiate a single LED based on the "led" subnode in DT.
This allows the user to control display brightness and blinking (backed
by hardware support) through the LED class API and triggers, and exposes
the display color. The LED will be named
"auxdisplay:<color>:<function>".
When running in dot-matrix mode and if no "led" subnode is found, the
driver falls back to the traditional backlight mode, to preserve
backwards compatibility.
Signed-off-by: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
Reviewed-by: Marek Behún <kabel@xxxxxxxxxx>
---
v6:
- Add Reviewed-by,
- Reorder operations in ht16k33_led_probe() to ease future conversion
to device properties,
v5:
- Add missing select NEW_LEDS,
v4:
- Add missing select LEDS_CLASS,
v3:
- Remove unneeded C++ comment,
- Use "err" instead of "error" to be consistent with existing driver
naming style,
- Make the creation of the LED device dependent on the presence of the
"led" subnode in DT, so it can be used in dot-matrix mode too.
- Use led_init_data() and devm_led_classdev_register_ext() to retrieve
all LED properties from DT, instead of manual LED name construction
based on just the "color" property,
v2:
- Use "auxdisplay" instead of DRIVER_NAME in LED name.
---
drivers/auxdisplay/Kconfig | 2 +
drivers/auxdisplay/ht16k33.c | 124 ++++++++++++++++++++++++++++++-----
2 files changed, 109 insertions(+), 17 deletions(-)
diff --git a/drivers/auxdisplay/Kconfig b/drivers/auxdisplay/Kconfig
index 42fc7b155de09dbc..e32ef7f9945d49b2 100644
--- a/drivers/auxdisplay/Kconfig
+++ b/drivers/auxdisplay/Kconfig
@@ -176,6 +176,8 @@ config HT16K33
select FB_SYS_IMAGEBLIT
select INPUT_MATRIXKMAP
select FB_BACKLIGHT
+ select NEW_LEDS
+ select LEDS_CLASS
select LINEDISP
help
Say yes here to add support for Holtek HT16K33, RAM mapping 16*8
diff --git a/drivers/auxdisplay/ht16k33.c b/drivers/auxdisplay/ht16k33.c
index 3b555e119e326cec..89ee5b4b3dfccb68 100644
--- a/drivers/auxdisplay/ht16k33.c
+++ b/drivers/auxdisplay/ht16k33.c
@@ -18,6 +18,7 @@
#include <linux/backlight.h>
#include <linux/input.h>
#include <linux/input/matrix_keypad.h>
+#include <linux/leds.h>
#include <linux/workqueue.h>
#include <linux/mm.h>
@@ -34,6 +35,10 @@
#define REG_DISPLAY_SETUP 0x80
#define REG_DISPLAY_SETUP_ON BIT(0)
+#define REG_DISPLAY_SETUP_BLINK_OFF (0 << 1)
+#define REG_DISPLAY_SETUP_BLINK_2HZ (1 << 1)
+#define REG_DISPLAY_SETUP_BLINK_1HZ (2 << 1)
+#define REG_DISPLAY_SETUP_BLINK_0HZ5 (3 << 1)
#define REG_ROWINT_SET 0xA0
#define REG_ROWINT_SET_INT_EN BIT(0)
@@ -94,12 +99,14 @@ struct ht16k33_seg {
struct ht16k33_priv {
struct i2c_client *client;
struct delayed_work work;
+ struct led_classdev led;
struct ht16k33_keypad keypad;
union {
struct ht16k33_fbdev fbdev;
struct ht16k33_seg seg;
};
enum display_type type;
+ uint8_t blink;
};
static const struct fb_fix_screeninfo ht16k33_fb_fix = {
@@ -158,7 +165,7 @@ static DEVICE_ATTR(map_seg14, 0644, map_seg_show,
map_seg_store);
static int ht16k33_display_on(struct ht16k33_priv *priv)
{
- uint8_t data = REG_DISPLAY_SETUP | REG_DISPLAY_SETUP_ON;
+ uint8_t data = REG_DISPLAY_SETUP | REG_DISPLAY_SETUP_ON | priv->blink;
return i2c_smbus_write_byte(priv->client, data);
}
@@ -173,8 +180,10 @@ static int ht16k33_brightness_set(struct ht16k33_priv
*priv,
{
int err;
- if (brightness == 0)
+ if (brightness == 0) {
+ priv->blink = REG_DISPLAY_SETUP_BLINK_OFF;
return ht16k33_display_off(priv);
+ }
err = ht16k33_display_on(priv);
if (err)
@@ -184,6 +193,49 @@ static int ht16k33_brightness_set(struct ht16k33_priv
*priv,
REG_BRIGHTNESS | (brightness - 1));
}
+static int ht16k33_brightness_set_blocking(struct led_classdev *led_cdev,
+ enum led_brightness brightness)
+{
+ struct ht16k33_priv *priv = container_of(led_cdev, struct ht16k33_priv,
+ led);
+
+ return ht16k33_brightness_set(priv, brightness);
+}
+
+static int ht16k33_blink_set(struct led_classdev *led_cdev,
+ unsigned long *delay_on, unsigned long *delay_off)
+{
+ struct ht16k33_priv *priv = container_of(led_cdev, struct ht16k33_priv,
+ led);
+ unsigned int delay;
+ uint8_t blink;
+ int err;
+
+ if (!*delay_on && !*delay_off) {
+ blink = REG_DISPLAY_SETUP_BLINK_1HZ;
+ delay = 1000;
+ } else if (*delay_on <= 750) {
+ blink = REG_DISPLAY_SETUP_BLINK_2HZ;
+ delay = 500;
+ } else if (*delay_on <= 1500) {
+ blink = REG_DISPLAY_SETUP_BLINK_1HZ;
+ delay = 1000;
+ } else {
+ blink = REG_DISPLAY_SETUP_BLINK_0HZ5;
+ delay = 2000;
+ }
+
+ err = i2c_smbus_write_byte(priv->client,
+ REG_DISPLAY_SETUP | REG_DISPLAY_SETUP_ON |
+ blink);
+ if (err)
+ return err;
+
+ priv->blink = blink;
+ *delay_on = *delay_off = delay;
+ return 0;
+}
+
static void ht16k33_fb_queue(struct ht16k33_priv *priv)
{
struct ht16k33_fbdev *fbdev = &priv->fbdev;
@@ -425,6 +477,35 @@ static void ht16k33_seg14_update(struct work_struct
*work)
i2c_smbus_write_i2c_block_data(priv->client, 0, ARRAY_SIZE(buf), buf);
}
+static int ht16k33_led_probe(struct device *dev, struct led_classdev *led,
+ unsigned int brightness)
+{
+ struct led_init_data init_data = {};
+ struct device_node *node;
+ int err;
+
+ /* The LED is optional */
+ node = of_get_child_by_name(dev->of_node, "led");
+ if (!node)
+ return 0;
+
+ init_data.fwnode = of_fwnode_handle(node);
+ init_data.devicename = "auxdisplay";
+ init_data.devname_mandatory = true;
+
+ led->brightness_set_blocking = ht16k33_brightness_set_blocking;
+ led->blink_set = ht16k33_blink_set;
+ led->flags = LED_CORE_SUSPENDRESUME;
+ led->brightness = brightness;
+ led->max_brightness = MAX_BRIGHTNESS;
What do you think about adding a default trigger and making it 'backlight'?
led->default_trigger = "blacklight";
Or as an alternative, suggesting linux,default-trigger = "backlight" in the
docs? Since the led class won't respond to blank events by just making it's
function LED_FUNCTION_BACKLIGHT.
led {
function = LED_FUNCTION_BACKLIGHT;
color = <LED_COLOR_ID_GREEN>;
linux,default-trigger = "backlight";
};
I noticed blanking is broken. The backlight device (or LED device with
backlight trigger) doens't get notified when the framebuffer is blanked since
the driver doesn't implement fb_blank.
Right now:
echo 1 > /sys/class/graphics/fb0/blank
|
sh: write error: Invalid argument
Due to:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/video/fbdev/core/fbmem.c?h=v5.15-rc3#n1078
Something like this fixes it.
diff --git a/drivers/auxdisplay/ht16k33.c b/drivers/auxdisplay/ht16k33.c
index 89ee5b4b3dfc..0883d5252c81 100644
--- a/drivers/auxdisplay/ht16k33.c
+++ b/drivers/auxdisplay/ht16k33.c
@@ -346,6 +346,15 @@ static int ht16k33_mmap(struct fb_info *info, struct
vm_area_struct *vma)
return vm_map_pages_zero(vma, &pages, 1);
}
+/*
+ * Blank events will be passed to the backlight device (or the LED device if
+ * it's trigger is 'backlight') when we return 0 here.
+ */
+static int ht16k33_blank(int blank, struct fb_info *info)
+{
+ return 0;
+}
+
static const struct fb_ops ht16k33_fb_ops = {
.owner = THIS_MODULE,
.fb_read = fb_sys_read,
@@ -354,6 +363,7 @@ static const struct fb_ops ht16k33_fb_ops = {
.fb_copyarea = sys_copyarea,
.fb_imageblit = sys_imageblit,
.fb_mmap = ht16k33_mmap,
+ .fb_blank = ht16k33_blank,
};
/*
Feel free to include (something like) this in the patch stack.
+
+ err = devm_led_classdev_register_ext(dev, led, &init_data);
+ if (err)
+ dev_err(dev, "Failed to register LED\n");
You might want to call ht16k33_brightness_set(priv, brightness) here to get a
know value into the display setup register (0x80).
Right now if I enable hardware blinking and (soft)reboot my board it keeps on
blinking even after a re-probe.
+
+ return err;
+}
+
static int ht16k33_keypad_probe(struct i2c_client *client,
struct ht16k33_keypad *keypad)
{
@@ -498,24 +579,28 @@ static int ht16k33_fbdev_probe(struct device *dev,
struct ht16k33_priv *priv,
uint32_t brightness)
{
struct ht16k33_fbdev *fbdev = &priv->fbdev;
- struct backlight_properties bl_props;
- struct backlight_device *bl;
+ struct backlight_device *bl = NULL;
int err;
- /* Backlight */
- memset(&bl_props, 0, sizeof(struct backlight_properties));
- bl_props.type = BACKLIGHT_RAW;
- bl_props.max_brightness = MAX_BRIGHTNESS;
+ if (!priv->led.dev) {
+ /* backwards compatibility with DT lacking an led subnode */
+ struct backlight_properties bl_props;
- bl = devm_backlight_device_register(dev, DRIVER_NAME"-bl", dev, priv,
- &ht16k33_bl_ops, &bl_props);
- if (IS_ERR(bl)) {
- dev_err(dev, "failed to register backlight\n");
- return PTR_ERR(bl);
- }
+ memset(&bl_props, 0, sizeof(struct backlight_properties));
+ bl_props.type = BACKLIGHT_RAW;
+ bl_props.max_brightness = MAX_BRIGHTNESS;
+
+ bl = devm_backlight_device_register(dev, DRIVER_NAME"-bl", dev,
+ priv, &ht16k33_bl_ops,
+ &bl_props);
+ if (IS_ERR(bl)) {
+ dev_err(dev, "failed to register backlight\n");
+ return PTR_ERR(bl);
+ }
- bl->props.brightness = brightness;
- ht16k33_bl_update_status(bl);
+ bl->props.brightness = brightness;
+ ht16k33_bl_update_status(bl);
+ }
/* Framebuffer (2 bytes per column) */
BUILD_BUG_ON(PAGE_SIZE < HT16K33_FB_SIZE);
@@ -575,7 +660,7 @@ static int ht16k33_seg_probe(struct device *dev, struct
ht16k33_priv *priv,
struct ht16k33_seg *seg = &priv->seg;
int err;
- err = ht16k33_brightness_set(priv, MAX_BRIGHTNESS);
+ err = ht16k33_brightness_set(priv, brightness);
This looks like a bugfix for patch 17, maybe move this change there?
if (err)
return err;
@@ -653,6 +738,11 @@ static int ht16k33_probe(struct i2c_client *client)
dft_brightness = MAX_BRIGHTNESS;
}
+ /* LED */
+ err = ht16k33_led_probe(dev, &priv->led, dft_brightness);
+ if (err)
+ return err;
+
/* Keypad */
if (client->irq > 0) {
err = ht16k33_keypad_probe(client, &priv->keypad);
Gr{oetje,eeting}s,
Robin