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i2c: mux: gpio: Add support for the 'settle-time-us' property

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Some hardware need some time to switch from a bus to another. This can
cause the first transfers following the selection of a bus to fail.
There is no way to configure this kind of waiting time in the driver.

Add support for the 'settle-time-us' device-tree property. When set,
the i2c_mux_gpio_select() applies a delay before returning, leaving
enough time to the hardware to switch to the new bus.

Signed-off-by: Bastien Curutchet <bastien.curutchet@bootlin.com>
Reviewed-by: Andi Shyti <andi.shyti@kernel.org>
Acked-by: Peter Rosin <peda@axentia.se>
Signed-off-by: Andi Shyti <andi.shyti@kernel.org>
This commit is contained in:
Bastien Curutchet 2024-06-17 14:08:18 +02:00 committed by Andi Shyti
parent a618d86d5a
commit 45b8ee7182
2 changed files with 8 additions and 0 deletions
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6
drivers/i2c/muxes/i2c-mux-gpio.c
View File

@ -6,6 +6,7 @@
*/
#include <linux/bits.h>
#include <linux/delay.h>
#include <linux/gpio/consumer.h>
#include <linux/gpio/driver.h>
#include <linux/i2c.h>
@ -37,6 +38,9 @@ static int i2c_mux_gpio_select(struct i2c_mux_core *muxc, u32 chan)
i2c_mux_gpio_set(mux, chan);
if (mux->data.settle_time)
fsleep(mux->data.settle_time);
return 0;
}
@ -116,6 +120,8 @@ static int i2c_mux_gpio_probe_fw(struct gpiomux *mux,
if (device_property_read_u32(dev, "idle-state", &mux->data.idle))
mux->data.idle = I2C_MUX_GPIO_NO_IDLE;
device_property_read_u32(dev, "settle-time-us", &mux->data.settle_time);
return 0;
}

2
include/linux/platform_data/i2c-mux-gpio.h
View File

@ -19,6 +19,7 @@
* position
* @n_values: Number of multiplexer positions (busses to instantiate)
* @idle: Bitmask to write to MUX when idle or GPIO_I2CMUX_NO_IDLE if not used
* @settle_time: Delay to wait when a new bus is selected
*/
struct i2c_mux_gpio_platform_data {
int parent;
@ -26,6 +27,7 @@ struct i2c_mux_gpio_platform_data {
const unsigned *values;
int n_values;
unsigned idle;
u32 settle_time;
};
#endif /* _LINUX_I2C_MUX_GPIO_H */