clk: add stub clock driver
Add a stub clock driver which can be used to bind clock controllers
which aren't required for the platform to boot, but which are needed for
U-Boot drivers to work.
In addition, add a NOP parent driver to allow for binding the parent
nodes of the clock.
Initially this driver supports a Qualcomm platform where the MMC driver
tries to fetch the RPM clock controller, which is not actually required
for the device to work.
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Acked-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Signed-off-by: Caleb Connolly <caleb.connolly@linaro.org>
diff --git a/drivers/clk/clk-stub.c b/drivers/clk/clk-stub.c
new file mode 100644
index 0000000..ea81703
--- /dev/null
+++ b/drivers/clk/clk-stub.c
@@ -0,0 +1,66 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Stub clk driver for non-essential clocks.
+ *
+ * This driver should be used for clock controllers
+ * which are described as dependencies in DT but aren't
+ * actually necessary for hardware functionality.
+ */
+
+#include <clk-uclass.h>
+#include <dm.h>
+
+/* NOP parent nodes to stub clocks */
+static const struct udevice_id nop_parent_ids[] = {
+ { .compatible = "qcom,rpm-proc" },
+ { .compatible = "qcom,glink-rpm" },
+ { .compatible = "qcom,rpm-sm6115" },
+ { }
+};
+
+U_BOOT_DRIVER(nop_parent) = {
+ .name = "nop_parent",
+ .id = UCLASS_NOP,
+ .of_match = nop_parent_ids,
+ .bind = dm_scan_fdt_dev,
+ .flags = DM_FLAG_DEFAULT_PD_CTRL_OFF,
+};
+
+static ulong stub_clk_set_rate(struct clk *clk, ulong rate)
+{
+ return (clk->rate = rate);
+}
+
+static ulong stub_clk_get_rate(struct clk *clk)
+{
+ return clk->rate;
+}
+
+static int stub_clk_nop(struct clk *clk)
+{
+ return 0;
+}
+
+static struct clk_ops stub_clk_ops = {
+ .set_rate = stub_clk_set_rate,
+ .get_rate = stub_clk_get_rate,
+ .enable = stub_clk_nop,
+ .disable = stub_clk_nop,
+};
+
+static const struct udevice_id stub_clk_ids[] = {
+ { .compatible = "qcom,rpmcc" },
+ { .compatible = "qcom,sm8250-rpmh-clk" },
+ { .compatible = "qcom,sm8550-rpmh-clk" },
+ { .compatible = "qcom,sm8650-rpmh-clk" },
+ { }
+};
+
+U_BOOT_DRIVER(clk_stub) = {
+ .name = "clk_stub",
+ .id = UCLASS_CLK,
+ .ops = &stub_clk_ops,
+ .of_match = stub_clk_ids,
+ .flags = DM_FLAG_DEFAULT_PD_CTRL_OFF,
+};
+