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 ---

doc/device-tree-bindings/i2c/i2c-gpio.txt | 2 ++ drivers/i2c/i2c-gpio.c | 10 ++++++++-- 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/doc/device-tree-bindings/i2c/i2c-gpio.txt b/doc/device-tree-bindings/i2c/i2c-gpio.txt index b06b829933..bb00854f33 100644 --- a/doc/device-tree-bindings/i2c/i2c-gpio.txt +++ b/doc/device-tree-bindings/i2c/i2c-gpio.txt @@ -20,6 +20,8 @@ Optional: Run deblocking sequence when the driver gets probed. * i2c-gpio,scl-output-only; Set if SCL is an output only +* i2c-gpio,sda-output-only; + Set if SDA is an output only

Example:

diff --git a/drivers/i2c/i2c-gpio.c b/drivers/i2c/i2c-gpio.c index e0a575fb4a..00aef40e34 100644 --- a/drivers/i2c/i2c-gpio.c +++ b/drivers/i2c/i2c-gpio.c @@ -101,7 +101,7 @@ static int i2c_gpio_read_bit(struct i2c_gpio_bus *bus, int delay)

bus->set_scl(bus, 1); udelay(delay); - value = bus->get_sda(bus); + value = bus->get_sda ? bus->get_sda(bus) : 0; udelay(delay); bus->set_scl(bus, 0); 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;

+ if (!bus->get_sda) + return -EOPNOTSUPP; + debug("%s: chip %x buffer: %p len %d\n", __func__, chip, buffer, len);

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", 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; if (dev_read_bool(dev, "i2c-gpio,scl-output-only")) bus->set_scl = i2c_gpio_scl_set_output_only;