interconnect: icc-rpm: Support child NoC device probe

As shown in downstream DT[1], the System NoC of QCM2290 is modelled
using 4 fab/noc devices: sys_noc + qup_virt + mmnrt_virt + mmrt_virt.
Among those 3 virtual devices, qup is owned by RPM and has no regmap
resource, while mmnrt and mmrt are owned by AP and share the same
regmap as sys_noc.  So it's logical to represent these virtual devices
as child nodes of sys_noc in DT, so that such configuration can be
supported with a couple of changes on qnoc_probe():

- If there are child nodes, populate them.
- If the device descriptor has .regmap_cfg but there is no IOMEM
  resource for the device, use parent's regmap.

[1] https://android.googlesource.com/kernel/msm-extra/devicetree/+/refs/tags/android-11.0.0_r0.56/qcom/scuba-bus.dtsi

Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
Link: https://lore.kernel.org/r/20211215002324.1727-4-shawn.guo@linaro.org
Signed-off-by: Georgi Djakov <djakov@kernel.org>

diff --git a/drivers/interconnect/qcom/icc-rpm.c b/drivers/interconnect/qcom/icc-rpm.c
index d8ea9bb479b121c1efe490892e6f32c7c4ff271e..34125e8f8b60d2c0e0f011281afdfac92506e08e 100644 (file)
--- a/drivers/interconnect/qcom/icc-rpm.c
+++ b/drivers/interconnect/qcom/icc-rpm.c
@@ -349,8 +349,13 @@ int qnoc_probe(struct platform_device *pdev)
                void __iomem *mmio;
 
                res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
-               if (!res)
+               if (!res) {
+                       /* Try parent's regmap */
+                       qp->regmap = dev_get_regmap(dev->parent, NULL);
+                       if (qp->regmap)
+                               goto regmap_done;
                        return -ENODEV;
+               }
 
                mmio = devm_ioremap_resource(dev, res);
 
@@ -366,6 +371,7 @@ int qnoc_probe(struct platform_device *pdev)
                }
        }
 
+regmap_done:
        ret = devm_clk_bulk_get(dev, qp->num_clks, qp->bus_clks);
        if (ret)
                return ret;
@@ -417,6 +423,10 @@ int qnoc_probe(struct platform_device *pdev)
 
        platform_set_drvdata(pdev, qp);
 
+       /* Populate child NoC devices if any */
+       if (of_get_child_count(dev->of_node) > 0)
+               return of_platform_populate(dev->of_node, NULL, NULL, dev);
+
        return 0;
 err:
        icc_nodes_remove(provider);