linux-kernel - Re: [PATCH v8 05/13] clk: rp1: Add support for clocks provided by RP1

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Message-ID: <23ac3d05-5fb7-4cd8-bb87-cf1f3eab521d@gmx.net>
Date: Mon, 14 Apr 2025 14:09:29 +0200
From: Stefan Wahren <wahrenst@....net>
To: Andrea della Porta <andrea.porta@...e.com>,
 Michael Turquette <mturquette@...libre.com>, Stephen Boyd
 <sboyd@...nel.org>, Rob Herring <robh@...nel.org>,
 Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley
 <conor+dt@...nel.org>, Florian Fainelli <florian.fainelli@...adcom.com>,
 Broadcom internal kernel review list
 <bcm-kernel-feedback-list@...adcom.com>,
 Lorenzo Pieralisi <lpieralisi@...nel.org>,
 Krzysztof Wilczynski <kw@...ux.com>,
 Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>,
 Bjorn Helgaas <bhelgaas@...gle.com>, Linus Walleij
 <linus.walleij@...aro.org>, Catalin Marinas <catalin.marinas@....com>,
 Will Deacon <will@...nel.org>, Bartosz Golaszewski <brgl@...ev.pl>,
 Derek Kiernan <derek.kiernan@....com>, Dragan Cvetic
 <dragan.cvetic@....com>, Arnd Bergmann <arnd@...db.de>,
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
 Saravana Kannan <saravanak@...gle.com>, linux-clk@...r.kernel.org,
 devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
 linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org,
 linux-gpio@...r.kernel.org, Masahiro Yamada <masahiroy@...nel.org>,
 Herve Codina <herve.codina@...tlin.com>,
 Luca Ceresoli <luca.ceresoli@...tlin.com>,
 Thomas Petazzoni <thomas.petazzoni@...tlin.com>, Andrew Lunn
 <andrew@...n.ch>, Phil Elwell <phil@...pberrypi.com>,
 Dave Stevenson <dave.stevenson@...pberrypi.com>, kernel-list@...pberrypi.com
Subject: Re: [PATCH v8 05/13] clk: rp1: Add support for clocks provided by RP1

Hi Andrea,

Am 19.03.25 um 22:52 schrieb Andrea della Porta:
> RaspberryPi RP1 is an MFD providing, among other peripherals, several
> clock generators and PLLs that drives the sub-peripherals.
> Add the driver to support the clock providers.
>
> Signed-off-by: Andrea della Porta <andrea.porta@...e.com>
> ---
>   MAINTAINERS           |    5 +
>   drivers/clk/Kconfig   |    9 +
>   drivers/clk/Makefile  |    1 +
>   drivers/clk/clk-rp1.c | 1512 +++++++++++++++++++++++++++++++++++++++++
>   4 files changed, 1527 insertions(+)
>   create mode 100644 drivers/clk/clk-rp1.c
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 896a307fa065..75263700370d 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -19748,6 +19748,11 @@ S:	Maintained
>   F:	Documentation/devicetree/bindings/media/raspberrypi,rp1-cfe.yaml
>   F:	drivers/media/platform/raspberrypi/rp1-cfe/
>
> +RASPBERRY PI RP1 PCI DRIVER
> +M:	Andrea della Porta <andrea.porta@...e.com>
> +S:	Maintained
> +F:	drivers/clk/clk-rp1.c
> +
>   RC-CORE / LIRC FRAMEWORK
>   M:	Sean Young <sean@...s.org>
>   L:	linux-media@...r.kernel.org
> diff --git a/drivers/clk/Kconfig b/drivers/clk/Kconfig
> index 713573b6c86c..cff90de71409 100644
> --- a/drivers/clk/Kconfig
> +++ b/drivers/clk/Kconfig
> @@ -88,6 +88,15 @@ config COMMON_CLK_RK808
>   	  These multi-function devices have two fixed-rate oscillators, clocked at 32KHz each.
>   	  Clkout1 is always on, Clkout2 can off by control register.
>
> +config COMMON_CLK_RP1
> +	tristate "Raspberry Pi RP1-based clock support"
> +	depends on MISC_RP1 || COMPILE_TEST
> +	default MISC_RP1
> +	help
> +	  Enable common clock framework support for Raspberry Pi RP1.
> +	  This multi-function device has 3 main PLLs and several clock
> +	  generators to drive the internal sub-peripherals.
> +
>   config COMMON_CLK_HI655X
>   	tristate "Clock driver for Hi655x" if EXPERT
>   	depends on (MFD_HI655X_PMIC || COMPILE_TEST)
> diff --git a/drivers/clk/Makefile b/drivers/clk/Makefile
> index bf4bd45adc3a..ff3993ed7e09 100644
> --- a/drivers/clk/Makefile
> +++ b/drivers/clk/Makefile
> @@ -84,6 +84,7 @@ obj-$(CONFIG_CLK_LS1028A_PLLDIG)	+= clk-plldig.o
>   obj-$(CONFIG_COMMON_CLK_PWM)		+= clk-pwm.o
>   obj-$(CONFIG_CLK_QORIQ)			+= clk-qoriq.o
>   obj-$(CONFIG_COMMON_CLK_RK808)		+= clk-rk808.o
> +obj-$(CONFIG_COMMON_CLK_RP1)            += clk-rp1.o
>   obj-$(CONFIG_COMMON_CLK_HI655X)		+= clk-hi655x.o
>   obj-$(CONFIG_COMMON_CLK_S2MPS11)	+= clk-s2mps11.o
>   obj-$(CONFIG_COMMON_CLK_SCMI)           += clk-scmi.o
> diff --git a/drivers/clk/clk-rp1.c b/drivers/clk/clk-rp1.c
> new file mode 100644
> index 000000000000..72c74e344c1d
> --- /dev/null
> +++ b/drivers/clk/clk-rp1.c
> @@ -0,0 +1,1512 @@
> +// SPDX-License-Identifier: GPL-2.0
...
> +
> +static int rp1_pll_divider_set_rate(struct clk_hw *hw,
> +				    unsigned long rate,
> +				    unsigned long parent_rate)
> +{
> +	struct rp1_clk_desc *divider = container_of(hw, struct rp1_clk_desc, div.hw);
> +	struct rp1_clockman *clockman = divider->clockman;
> +	const struct rp1_pll_data *data = divider->data;
> +	u32 div, sec;
> +
> +	div = DIV_ROUND_UP_ULL(parent_rate, rate);
> +	div = clamp(div, 8u, 19u);
> +
> +	spin_lock(&clockman->regs_lock);
> +	sec = clockman_read(clockman, data->ctrl_reg);
> +	sec &= ~PLL_SEC_DIV_MASK;
> +	sec |= FIELD_PREP(PLL_SEC_DIV_MASK, div);
> +
> +	/* Must keep the divider in reset to change the value. */
> +	sec |= PLL_SEC_RST;
> +	clockman_write(clockman, data->ctrl_reg, sec);
> +
> +	/* TODO: must sleep 10 pll vco cycles */
Is it possible to implement this with some kind of xsleep or xdelay?
> +	sec &= ~PLL_SEC_RST;
> +	clockman_write(clockman, data->ctrl_reg, sec);
> +	spin_unlock(&clockman->regs_lock);
> +
> +	return 0;
> +}
> +
>