[PATCH 1/3] i3c: fix i2c and i3c scl rate by bus mode

[Vitor Soares]

Currently in case of mixed slow bus topologie and all i2c devices
support FM+ speed, the i3c subsystem limite the SCL to FM speed.
Also in case on mixed slow bus mode the max speed for both
i2c or i3c transfers is FM or FM+.

This patch fix the definition of i2c and i3c scl rate based on bus
topologie and LVR[4] if no user input.
In case of mixed slow mode the i3c scl rate is overridden.

Fixes: 3a379bbcea0a ("i3c: Add core I3C infrastructure")
Signed-off-by: Vitor Soares <vitor.soa...@synopsys.com>
Cc: Boris Brezillon <bbrezil...@kernel.org>
Cc: <sta...@vger.kernel.org>
Cc: <linux-kernel@vger.kernel.org>
---
 drivers/i3c/master.c | 39 +++++++++++++++++++++++++--------------
 1 file changed, 25 insertions(+), 14 deletions(-)

diff --git a/drivers/i3c/master.c b/drivers/i3c/master.c
index 909c2ad..1c4a86a 100644
--- a/drivers/i3c/master.c
+++ b/drivers/i3c/master.c
@@ -564,20 +564,30 @@ 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 i2c_scl_rate)
 {
        i3cbus->mode = mode;
 
-       if (!i3cbus->scl_rate.i3c)
-               i3cbus->scl_rate.i3c = I3C_BUS_TYP_I3C_SCL_RATE;
-
-       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 = i2c_scl_rate;
+               break;
+       case I3C_BUS_MODE_MIXED_SLOW:
+               if (!i3cbus->scl_rate.i2c)
+                       i3cbus->scl_rate.i2c = i2c_scl_rate;
+               i3cbus->scl_rate.i3c = i3cbus->scl_rate.i2c;
+               break;
+       default:
+               return -EINVAL;
        }
-
        /*
         * I3C/I2C frequency may have been overridden, check that user-provided
         * values are not exceeding max possible frequency.
@@ -1980,9 +1990,6 @@ 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);
 
@@ -2432,6 +2439,7 @@ 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;
@@ -2481,9 +2489,12 @@ 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;
 
-- 
2.7.4