i3c: fix i2c and i3c scl rate by bus mode

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@synopsys.com>
Cc: Boris Brezillon <bbrezillon@kernel.org>
Cc: <stable@vger.kernel.org>
Cc: <linux-kernel@vger.kernel.org>
Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>

diff --git a/drivers/i3c/master.c b/drivers/i3c/master.c
index b9d2b88928e156ef2bcbe630e83d38b68101cec2..54026be03998fc11524be2ac619aa83524fab3bf 100644 (file)
--- a/drivers/i3c/master.c
+++ b/drivers/i3c/master.c
@@ -91,6 +91,12 @@ void i3c_bus_normaluse_unlock(struct i3c_bus *bus)
        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_masterdev_type = {
        .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.
@@ -1976,9 +2000,6 @@ of_i3c_master_add_i2c_boardinfo(struct i3c_master_controller *master,
        /* 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);
 
@@ -2424,6 +2445,7 @@ int i3c_master_register(struct i3c_master_controller *master,
                        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;
@@ -2473,9 +2495,12 @@ int i3c_master_register(struct i3c_master_controller *master,
                        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;