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i3c: add mixed limited bus mode 

The i3c bus spec defines a bus configuration where i2c devices don't
have a 50ns filter but support SCL running at SDR max rate (12.5MHz).

This patch introduces the limited bus mode so that users can use
a higher speed in presence of i2c devices index 1.

Signed-off-by: Vitor Soares <vitor.soares@synopsys.com>
Cc: Boris Brezillon <bbrezillon@kernel.org>
Cc: <linux-kernel@vger.kernel.org>
Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
This commit is contained in:
Vitor Soares 2019-06-19 20:36:32 +02:00 committed by Boris Brezillon
parent ecc8fb54bd
commit cbf4f7325a
2 changed files with 10 additions and 0 deletions
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5
drivers/i3c/master.c
View File

@ -470,6 +470,7 @@ static int i3c_bus_init(struct i3c_bus *i3cbus)
static const char * const i3c_bus_mode_strings[] = {
[I3C_BUS_MODE_PURE] = "pure",
[I3C_BUS_MODE_MIXED_FAST] = "mixed-fast",
[I3C_BUS_MODE_MIXED_LIMITED] = "mixed-limited",
[I3C_BUS_MODE_MIXED_SLOW] = "mixed-slow",
};
@ -584,6 +585,7 @@ int i3c_bus_set_mode(struct i3c_bus *i3cbus, enum i3c_bus_mode mode,
i3cbus->scl_rate.i3c = I3C_BUS_TYP_I3C_SCL_RATE;
break;
case I3C_BUS_MODE_MIXED_FAST:
case I3C_BUS_MODE_MIXED_LIMITED:
if (!i3cbus->scl_rate.i3c)
i3cbus->scl_rate.i3c = I3C_BUS_TYP_I3C_SCL_RATE;
if (!i3cbus->scl_rate.i2c)
@ -2487,6 +2489,9 @@ int i3c_master_register(struct i3c_master_controller *master,
mode = I3C_BUS_MODE_MIXED_FAST;
break;
case I3C_LVR_I2C_INDEX(1):
if (mode < I3C_BUS_MODE_MIXED_LIMITED)
mode = I3C_BUS_MODE_MIXED_LIMITED;
break;
case I3C_LVR_I2C_INDEX(2):
if (mode < I3C_BUS_MODE_MIXED_SLOW)
mode = I3C_BUS_MODE_MIXED_SLOW;

5
include/linux/i3c/master.h
View File

@ -250,12 +250,17 @@ struct i3c_device {
* the bus. The only impact in this mode is that the
* high SCL pulse has to stay below 50ns to trick I2C
* devices when transmitting I3C frames
* @I3C_BUS_MODE_MIXED_LIMITED: I2C devices without 50ns spike filter are
* present on the bus. However they allow
* compliance up to the maximum SDR SCL clock
* frequency.
* @I3C_BUS_MODE_MIXED_SLOW: I2C devices without 50ns spike filter are present
* on the bus
*/
enum i3c_bus_mode {
I3C_BUS_MODE_PURE,
I3C_BUS_MODE_MIXED_FAST,
I3C_BUS_MODE_MIXED_LIMITED,
I3C_BUS_MODE_MIXED_SLOW,
};