[PATCH v2 1/2] clk: add stub clock driver

[Neil Armstrong]

On 27/05/2024 19:12, Caleb Connolly wrote:
> 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.
> 
> Signed-off-by: Caleb Connolly <caleb.connolly at linaro.org>
> ---
>   drivers/clk/Kconfig    |  7 ++++++
>   drivers/clk/Makefile   |  1 +
>   drivers/clk/clk-stub.c | 63 ++++++++++++++++++++++++++++++++++++++++++++++++++
>   3 files changed, 71 insertions(+)
> 
> diff --git a/drivers/clk/Kconfig b/drivers/clk/Kconfig
> index 9acbc47fe8ed..965bc4959403 100644
> --- a/drivers/clk/Kconfig
> +++ b/drivers/clk/Kconfig
> @@ -95,8 +95,15 @@ config SPL_CLK_GPIO
>   	help
>   	  Enable this option to add GPIO-controlled clock gate driver
>   	  in U-Boot SPL.
>   
> +config CLK_STUB
> +	bool "Stub clock driver"
> +	depends on CLK
> +	help
> +	  Enable this to provide a stub clock driver for non-essential clock
> +	  controllers.
> +
>   config CLK_BCM6345
>   	bool "Clock controller driver for BCM6345"
>   	depends on CLK && ARCH_BMIPS
>   	default y
> diff --git a/drivers/clk/Makefile b/drivers/clk/Makefile
> index 847b9b291100..b2cea41419b7 100644
> --- a/drivers/clk/Makefile
> +++ b/drivers/clk/Makefile
> @@ -10,8 +10,9 @@ obj-$(CONFIG_$(SPL_TPL_)CLK) += clk_fixed_factor.o
>   obj-$(CONFIG_$(SPL_TPL_)CLK_CCF) += clk.o clk-divider.o clk-mux.o clk-gate.o
>   obj-$(CONFIG_$(SPL_TPL_)CLK_CCF) += clk-fixed-factor.o
>   obj-$(CONFIG_$(SPL_TPL_)CLK_COMPOSITE_CCF) += clk-composite.o
>   obj-$(CONFIG_$(SPL_TPL_)CLK_GPIO) += clk-gpio.o
> +obj-$(CONFIG_CLK_STUB) += clk-stub.o
>   
>   obj-y += adi/
>   obj-y += analogbits/
>   obj-y += imx/
> diff --git a/drivers/clk/clk-stub.c b/drivers/clk/clk-stub.c
> new file mode 100644
> index 000000000000..3f9c758ef115
> --- /dev/null
> +++ b/drivers/clk/clk-stub.c
> @@ -0,0 +1,63 @@
> +// 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" },


If you resend, please add:
- qcom,sm8550-rpmh-clk
- qcom,sm8650-rpmh-clk

Thanks,
Neil

> +	{ }
> +};
> +
> +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,
> +};
> +
>