[v2,02/11] leds: aw200xx: support HWEN hardware control
Commit Message
HWEN is hardware control, which is used for enable/disable aw200xx chip.
It's high active, internally pulled down to GND.
After HWEN pin set high the chip begins to load the OTP information,
which takes 200us to complete. About 200us wait time is needed for
internal oscillator startup and display SRAM initialization. After
display SRAM initialization, the registers in page 1 to page 5 can be
configured via i2c interface.
Signed-off-by: Dmitry Rokosov <ddrokosov@salutedevices.com>
---
drivers/leds/leds-aw200xx.c | 29 +++++++++++++++++++++++++++++
1 file changed, 29 insertions(+)
Comments
On Wed, Oct 18, 2023 at 9:29 PM Dmitry Rokosov
<ddrokosov@salutedevices.com> wrote:
>
> HWEN is hardware control, which is used for enable/disable aw200xx chip.
> It's high active, internally pulled down to GND.
>
> After HWEN pin set high the chip begins to load the OTP information,
> which takes 200us to complete. About 200us wait time is needed for
> internal oscillator startup and display SRAM initialization. After
> display SRAM initialization, the registers in page 1 to page 5 can be
> configured via i2c interface.
Is there any Documentation update for this new binding?
...
> + chip->hwen = devm_gpiod_get_optional(&client->dev, "hwen", GPIOD_OUT_HIGH);
With _optional APIs we distinguish 3 cases: found, not found, error.
And error can be (among others) the deferred probe, meaning that GPIO
_is coming_. Hence the rule of thumb for the _optional() APIs is to
check for error and bail out on that condition (note, it's applicable
to any _optional() APIs, not limited by GPIO library).
...
> aw200xx_chip_reset(chip);
> + aw200xx_disable(chip);
It seems it can be modeled as a (GPIO) regulator. At least many
drivers do so, but I leave this to the maintainers to decide.
@@ -10,6 +10,7 @@
#include <linux/bitfield.h>
#include <linux/bits.h>
#include <linux/container_of.h>
+#include <linux/gpio/consumer.h>
#include <linux/i2c.h>
#include <linux/leds.h>
#include <linux/mod_devicetable.h>
@@ -116,6 +117,7 @@ struct aw200xx {
struct mutex mutex;
u32 num_leds;
u32 display_rows;
+ struct gpio_desc *hwen;
struct aw200xx_led leds[] __counted_by(num_leds);
};
@@ -358,6 +360,25 @@ static int aw200xx_chip_check(const struct aw200xx *const chip)
return 0;
}
+static void aw200xx_enable(const struct aw200xx *const chip)
+{
+ gpiod_set_value_cansleep(chip->hwen, 1);
+
+ /*
+ * After HWEN pin set high the chip begins to load the OTP information,
+ * which takes 200us to complete. About 200us wait time is needed for
+ * internal oscillator startup and display SRAM initialization. After
+ * display SRAM initialization, the registers in page1 to page5 can be
+ * configured via i2c interface.
+ */
+ fsleep(400);
+}
+
+static void aw200xx_disable(const struct aw200xx *const chip)
+{
+ return gpiod_set_value_cansleep(chip->hwen, 0);
+}
+
static int aw200xx_probe_fw(struct device *dev, struct aw200xx *chip)
{
struct fwnode_handle *child;
@@ -517,6 +538,10 @@ static int aw200xx_probe(struct i2c_client *client)
if (IS_ERR(chip->regmap))
return PTR_ERR(chip->regmap);
+ chip->hwen = devm_gpiod_get_optional(&client->dev, "hwen", GPIOD_OUT_HIGH);
+
+ aw200xx_enable(chip);
+
ret = aw200xx_chip_check(chip);
if (ret)
return ret;
@@ -537,6 +562,9 @@ static int aw200xx_probe(struct i2c_client *client)
ret = aw200xx_chip_init(chip);
out_unlock:
+ if (ret)
+ aw200xx_disable(chip);
+
mutex_unlock(&chip->mutex);
return ret;
}
@@ -546,6 +574,7 @@ static void aw200xx_remove(struct i2c_client *client)
struct aw200xx *chip = i2c_get_clientdata(client);
aw200xx_chip_reset(chip);
+ aw200xx_disable(chip);
mutex_destroy(&chip->mutex);
}