Merge tag 'idmapped-mounts-v5.12' of git://git.kernel.org/pub/scm/linux/kernel/git...

[linux-2.6-microblaze.git] / drivers / clk / clk-versaclock5.c

diff --git a/drivers/clk/clk-versaclock5.c b/drivers/clk/clk-versaclock5.c
index 43db673..344cd6c 100644 (file)
--- a/drivers/clk/clk-versaclock5.c
+++ b/drivers/clk/clk-versaclock5.c
@@ -759,6 +759,63 @@ static int vc5_update_power(struct device_node *np_output,
        return 0;
 }
 
+static int vc5_map_cap_value(u32 femtofarads)
+{
+       int mapped_value;
+
+       /*
+        * The datasheet explicitly states 9000 - 25000 with 0.5pF
+        * steps, but the Programmer's guide shows the steps are 0.430pF.
+        * After getting feedback from Renesas, the .5pF steps were the
+        * goal, but 430nF was the actual values.
+        * Because of this, the actual range goes to 22760 instead of 25000
+        */
+       if (femtofarads < 9000 || femtofarads > 22760)
+               return -EINVAL;
+
+       /*
+        * The Programmer's guide shows XTAL[5:0] but in reality,
+        * XTAL[0] and XTAL[1] are both LSB which makes the math
+        * strange.  With clarfication from Renesas, setting the
+        * values should be simpler by ignoring XTAL[0]
+        */
+       mapped_value = DIV_ROUND_CLOSEST(femtofarads - 9000, 430);
+
+       /*
+        * Since the calculation ignores XTAL[0], there is one
+        * special case where mapped_value = 32.  In reality, this means
+        * the real mapped value should be 111111b.  In other cases,
+        * the mapped_value needs to be shifted 1 to the left.
+        */
+       if (mapped_value > 31)
+               mapped_value = 0x3f;
+       else
+               mapped_value <<= 1;
+
+       return mapped_value;
+}
+static int vc5_update_cap_load(struct device_node *node, struct vc5_driver_data *vc5)
+{
+       u32 value;
+       int mapped_value;
+
+       if (!of_property_read_u32(node, "idt,xtal-load-femtofarads", &value)) {
+               mapped_value = vc5_map_cap_value(value);
+               if (mapped_value < 0)
+                       return mapped_value;
+
+               /*
+                * The mapped_value is really the high 6 bits of
+                * VC5_XTAL_X1_LOAD_CAP and VC5_XTAL_X2_LOAD_CAP, so
+                * shift the value 2 places.
+                */
+               regmap_update_bits(vc5->regmap, VC5_XTAL_X1_LOAD_CAP, ~0x03, mapped_value << 2);
+               regmap_update_bits(vc5->regmap, VC5_XTAL_X2_LOAD_CAP, ~0x03, mapped_value << 2);
+       }
+
+       return 0;
+}
+
 static int vc5_update_slew(struct device_node *np_output,
                           struct vc5_out_data *clk_out)
 {
@@ -884,6 +941,13 @@ static int vc5_probe(struct i2c_client *client, const struct i2c_device_id *id)
                return -EINVAL;
        }
 
+       /* Configure Optional Loading Capacitance for external XTAL */
+       if (!(vc5->chip_info->flags & VC5_HAS_INTERNAL_XTAL)) {
+               ret = vc5_update_cap_load(client->dev.of_node, vc5);
+               if (ret)
+                       goto err_clk_register;
+       }
+
        init.name = kasprintf(GFP_KERNEL, "%pOFn.mux", client->dev.of_node);
        init.ops = &vc5_mux_ops;
        init.flags = 0;