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i2c: i2c-gpio: add support for i2c-gpio,sda-output-only

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Some I2C slave devices are read-only and don't even answer with NACK.
For example FD65x segment LED controllers.
Make them usable with i2c-gpio,sda-output-only that are already supported
by Linux 6.3+.

Signed-off-by: Alex Shumsky <alexthreed@gmail.com>
Reviewed-by: Heiko Schocher <hs@denx.de>
This commit is contained in:
Alex Shumsky 2024-10-15 23:29:31 +03:00 • committed by Heiko Schocher
parent f7c9839a61
commit f315a48131
2 changed files with 10 additions and 2 deletions
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2
doc/device-tree-bindings/i2c/i2c-gpio.txt
View file

@ -20,6 +20,8 @@ Optional:
Run deblocking sequence when the driver gets probed. Run deblocking sequence when the driver gets probed.
* i2c-gpio,scl-output-only; * i2c-gpio,scl-output-only;
Set if SCL is an output only Set if SCL is an output only
* i2c-gpio,sda-output-only;
Set if SDA is an output only
Example: Example:

10
drivers/i2c/i2c-gpio.c
View file

@ -101,7 +101,7 @@ static int i2c_gpio_read_bit(struct i2c_gpio_bus *bus, int delay)
bus->set_scl(bus, 1); bus->set_scl(bus, 1);
udelay(delay); udelay(delay);
value = bus->get_sda(bus); value = bus->get_sda ? bus->get_sda(bus) : 0;
udelay(delay); udelay(delay);
bus->set_scl(bus, 0); bus->set_scl(bus, 0);
udelay(2 * delay); udelay(2 * delay);
@ -256,6 +256,9 @@ static int i2c_gpio_read_data(struct i2c_gpio_bus *bus, uchar chip,
{ {
unsigned int delay = bus->udelay; unsigned int delay = bus->udelay;
if (!bus->get_sda)
return -EOPNOTSUPP;
debug("%s: chip %x buffer: %p len %d\n", __func__, chip, buffer, len); debug("%s: chip %x buffer: %p len %d\n", __func__, chip, buffer, len);
while (len-- > 0) while (len-- > 0)
@ -353,7 +356,10 @@ static int i2c_gpio_of_to_plat(struct udevice *dev)
bus->udelay = dev_read_u32_default(dev, "i2c-gpio,delay-us", bus->udelay = dev_read_u32_default(dev, "i2c-gpio,delay-us",
DEFAULT_UDELAY); DEFAULT_UDELAY);
bus->get_sda = i2c_gpio_sda_get; if (dev_read_bool(dev, "i2c-gpio,sda-output-only"))
bus->get_sda = NULL;
else
bus->get_sda = i2c_gpio_sda_get;
bus->set_sda = i2c_gpio_sda_set; bus->set_sda = i2c_gpio_sda_set;
if (dev_read_bool(dev, "i2c-gpio,scl-output-only")) if (dev_read_bool(dev, "i2c-gpio,scl-output-only"))
bus->set_scl = i2c_gpio_scl_set_output_only; bus->set_scl = i2c_gpio_scl_set_output_only;