[PATCH 5.2 343/413] i3c: fix i2c and i3c scl rate by bus mode

From: Greg Kroah-Hartman
Date: Wed Jul 24 2019 - 16:24:41 EST


From: Vitor Soares <Vitor.Soares@xxxxxxxxxxxx>

commit ecc8fb54bd443bf69996d9d5ddb8d90a50f14936 upstream.

Currently the I3C framework limits SCL frequency to FM speed when
dealing with a mixed slow bus, even if all I2C devices are FM+ capable.

The core was also not accounting for I3C speed limitations when
operating in mixed slow mode and was erroneously using FM+ speed as the
max I2C speed when operating in mixed fast mode.

Fixes: 3a379bbcea0a ("i3c: Add core I3C infrastructure")
Signed-off-by: Vitor Soares <vitor.soares@xxxxxxxxxxxx>
Cc: Boris Brezillon <bbrezillon@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Cc: <linux-kernel@xxxxxxxxxxxxxxx>
Signed-off-by: Boris Brezillon <boris.brezillon@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
drivers/i3c/master.c | 51 ++++++++++++++++++++++++++++++++++++++-------------
1 file changed, 38 insertions(+), 13 deletions(-)

--- a/drivers/i3c/master.c
+++ b/drivers/i3c/master.c
@@ -91,6 +91,12 @@ void i3c_bus_normaluse_unlock(struct i3c
up_read(&bus->lock);
}

+static struct i3c_master_controller *
+i3c_bus_to_i3c_master(struct i3c_bus *i3cbus)
+{
+ return container_of(i3cbus, struct i3c_master_controller, bus);
+}
+
static struct i3c_master_controller *dev_to_i3cmaster(struct device *dev)
{
return container_of(dev, struct i3c_master_controller, dev);
@@ -565,20 +571,38 @@ static const struct device_type i3c_mast
.groups = i3c_masterdev_groups,
};

-int i3c_bus_set_mode(struct i3c_bus *i3cbus, enum i3c_bus_mode mode)
+int i3c_bus_set_mode(struct i3c_bus *i3cbus, enum i3c_bus_mode mode,
+ unsigned long max_i2c_scl_rate)
{
- i3cbus->mode = mode;
+ struct i3c_master_controller *master = i3c_bus_to_i3c_master(i3cbus);

- if (!i3cbus->scl_rate.i3c)
- i3cbus->scl_rate.i3c = I3C_BUS_TYP_I3C_SCL_RATE;
+ i3cbus->mode = mode;

- if (!i3cbus->scl_rate.i2c) {
- if (i3cbus->mode == I3C_BUS_MODE_MIXED_SLOW)
- i3cbus->scl_rate.i2c = I3C_BUS_I2C_FM_SCL_RATE;
- else
- i3cbus->scl_rate.i2c = I3C_BUS_I2C_FM_PLUS_SCL_RATE;
+ switch (i3cbus->mode) {
+ case I3C_BUS_MODE_PURE:
+ if (!i3cbus->scl_rate.i3c)
+ i3cbus->scl_rate.i3c = I3C_BUS_TYP_I3C_SCL_RATE;
+ break;
+ case I3C_BUS_MODE_MIXED_FAST:
+ if (!i3cbus->scl_rate.i3c)
+ i3cbus->scl_rate.i3c = I3C_BUS_TYP_I3C_SCL_RATE;
+ if (!i3cbus->scl_rate.i2c)
+ i3cbus->scl_rate.i2c = max_i2c_scl_rate;
+ break;
+ case I3C_BUS_MODE_MIXED_SLOW:
+ if (!i3cbus->scl_rate.i2c)
+ i3cbus->scl_rate.i2c = max_i2c_scl_rate;
+ if (!i3cbus->scl_rate.i3c ||
+ i3cbus->scl_rate.i3c > i3cbus->scl_rate.i2c)
+ i3cbus->scl_rate.i3c = i3cbus->scl_rate.i2c;
+ break;
+ default:
+ return -EINVAL;
}

+ dev_dbg(&master->dev, "i2c-scl = %ld Hz i3c-scl = %ld Hz\n",
+ i3cbus->scl_rate.i2c, i3cbus->scl_rate.i3c);
+
/*
* I3C/I2C frequency may have been overridden, check that user-provided
* values are not exceeding max possible frequency.
@@ -1966,9 +1990,6 @@ of_i3c_master_add_i2c_boardinfo(struct i
/* LVR is encoded in reg[2]. */
boardinfo->lvr = reg[2];

- if (boardinfo->lvr & I3C_LVR_I2C_FM_MODE)
- master->bus.scl_rate.i2c = I3C_BUS_I2C_FM_SCL_RATE;
-
list_add_tail(&boardinfo->node, &master->boardinfo.i2c);
of_node_get(node);

@@ -2417,6 +2438,7 @@ int i3c_master_register(struct i3c_maste
const struct i3c_master_controller_ops *ops,
bool secondary)
{
+ unsigned long i2c_scl_rate = I3C_BUS_I2C_FM_PLUS_SCL_RATE;
struct i3c_bus *i3cbus = i3c_master_get_bus(master);
enum i3c_bus_mode mode = I3C_BUS_MODE_PURE;
struct i2c_dev_boardinfo *i2cbi;
@@ -2466,9 +2488,12 @@ int i3c_master_register(struct i3c_maste
ret = -EINVAL;
goto err_put_dev;
}
+
+ if (i2cbi->lvr & I3C_LVR_I2C_FM_MODE)
+ i2c_scl_rate = I3C_BUS_I2C_FM_SCL_RATE;
}

- ret = i3c_bus_set_mode(i3cbus, mode);
+ ret = i3c_bus_set_mode(i3cbus, mode, i2c_scl_rate);
if (ret)
goto err_put_dev;