[PATCH] clk: Add GPIO-controlled clock gate driver

[Sean Anderson]

On 8/13/23 19:51, Marek Vasut wrote:
> Add driver which implements GPIO-controlled clock. The GPIO is used
> as a gate to enable/disable the clock. This matches linux clk-gpio.c
> driver, however this does not implement the GPIO mux part, which in
> U-Boot DM would be better fit in separate driver.
> 
> Signed-off-by: Marek Vasut <marek.vasut+renesas at mailbox.org>
> ---
> Cc: Lukasz Majewski <lukma at denx.de>
> Cc: Sean Anderson <seanga2 at gmail.com>
> ---
>   drivers/clk/Kconfig    | 13 +++++++++
>   drivers/clk/Makefile   |  1 +
>   drivers/clk/clk-gpio.c | 66 ++++++++++++++++++++++++++++++++++++++++++
>   3 files changed, 80 insertions(+)
>   create mode 100644 drivers/clk/clk-gpio.c
> 
> diff --git a/drivers/clk/Kconfig b/drivers/clk/Kconfig
> index 29859cdfa15..bfd23a99046 100644
> --- a/drivers/clk/Kconfig
> +++ b/drivers/clk/Kconfig
> @@ -83,6 +83,19 @@ config CLK_COMPOSITE_CCF
>   	  Enable this option if you want to (re-)use the Linux kernel's Common
>   	  Clock Framework [CCF] composite code in U-Boot's clock driver.
>   
> +config CLK_GPIO
> +	bool "GPIO-controlled clock gate driver"
> +	depends on CLK
> +	help
> +	  Enable this option to add GPIO-controlled clock gate driver.
> +
> +config SPL_CLK_GPIO
> +	bool "GPIO-controlled clock gate driver in SPL"
> +	depends on SPL_CLK
> +	help
> +	  Enable this option to add GPIO-controlled clock gate driver
> +	  in U-Boot SPL.
> +
>   config CLK_BCM6345
>   	bool "Clock controller driver for BCM6345"
>   	depends on CLK && ARCH_BMIPS
> diff --git a/drivers/clk/Makefile b/drivers/clk/Makefile
> index e22c8cf291f..26bf429acbc 100644
> --- a/drivers/clk/Makefile
> +++ b/drivers/clk/Makefile
> @@ -10,6 +10,7 @@ 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-y += analogbits/
>   obj-y += imx/
> diff --git a/drivers/clk/clk-gpio.c b/drivers/clk/clk-gpio.c
> new file mode 100644
> index 00000000000..26d795b9783
> --- /dev/null
> +++ b/drivers/clk/clk-gpio.c
> @@ -0,0 +1,66 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * Copyright (C) 2023 Marek Vasut <marek.vasut+renesas at mailbox.org>
> + */
> +
> +#include <asm/gpio.h>
> +#include <common.h>
> +#include <clk-uclass.h>
> +#include <dm.h>
> +
> +struct clk_gpio_priv {
> +	struct gpio_desc	enable;
> +};
> +
> +static int clk_gpio_enable(struct clk *clk)
> +{
> +	struct clk_gpio_priv *priv = dev_get_priv(clk->dev);
> +
> +	dm_gpio_set_value(&priv->enable, 1);
> +
> +	return 0;
> +}
> +
> +static int clk_gpio_disable(struct clk *clk)
> +{
> +	struct clk_gpio_priv *priv = dev_get_priv(clk->dev);
> +
> +	dm_gpio_set_value(&priv->enable, 0);
> +
> +	return 0;
> +}
> +
> +const struct clk_ops clk_gpio_ops = {
> +	.enable		= clk_gpio_enable,
> +	.disable	= clk_gpio_disable,
> +};
> +
> +static int clk_gpio_probe(struct udevice *dev)
> +{
> +	struct clk_gpio_priv *priv = dev_get_priv(dev);
> +
> +	return gpio_request_by_name(dev, "enable-gpios", 0,
> +				    &priv->enable, GPIOD_IS_OUT);
> +}
> +
> +/*
> + * When implementing clk-mux-clock, use gpio_request_list_by_name
> + * and implement get_rate/set_rate/set_parent ops. This should be
> + * in a separate driver and with separate Kconfig option to enable
> + * that driver, since unlike Linux implementation, the U-Boot DM
> + * integration would be orthogonal to this driver.
> + */
> +static const struct udevice_id clk_gpio_match[] = {
> +	{ .compatible = "gpio-gate-clock" },
> +	{ /* sentinel */ }
> +};
> +
> +U_BOOT_DRIVER(gpio_gate_clock) = {
> +	.name		= "gpio_clock",
> +	.id		= UCLASS_CLK,
> +	.of_match	= clk_gpio_match,
> +	.probe		= clk_gpio_probe,
> +	.priv_auto	= sizeof(struct clk_gpio_priv),
> +	.ops		= &clk_gpio_ops,
> +	.flags		= DM_FLAG_PRE_RELOC,
> +};

Reviewed-by: Sean Anderson <seanga2 at gmail.com>