linux-kernel - Re: [PATCH v2 4/6] reset: anlogic: add support for Anlogic DR1V90 resets

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Message-ID: <36d28431c41ec9ed86487135d81e50b136ee0fae.camel@pengutronix.de>
Date: Tue, 28 Oct 2025 09:17:57 +0100
From: Philipp Zabel <p.zabel@...gutronix.de>
To: Junhui Liu <junhui.liu@...moral.tech>, 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>, Paul Walmsley <pjw@...nel.org>, Palmer Dabbelt
	 <palmer@...belt.com>, Albert Ou <aou@...s.berkeley.edu>, Alexandre Ghiti
	 <alex@...ti.fr>
Cc: linux-clk@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-riscv@...ts.infradead.org, devicetree@...r.kernel.org
Subject: Re: [PATCH v2 4/6] reset: anlogic: add support for Anlogic DR1V90
 resets

On So, 2025-10-26 at 22:00 +0800, Junhui Liu wrote:
> Add reset controller support for the Anlogic DR1V90 SoC, which is an
> auxiliary device associated with the Clock and Reset Unit (CRU). All
> resets are active-low.
> 
> Signed-off-by: Junhui Liu <junhui.liu@...moral.tech>
> ---
>  drivers/reset/Kconfig        |   9 +++
>  drivers/reset/Makefile       |   1 +
>  drivers/reset/reset-dr1v90.c | 135 +++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 145 insertions(+)
> 
[...]
> diff --git a/drivers/reset/reset-dr1v90.c b/drivers/reset/reset-dr1v90.c
> new file mode 100644
> index 0000000000000000000000000000000000000000..eb9064e3ab454fb39adc1ad426f458e39bb6169e
> --- /dev/null
> +++ b/drivers/reset/reset-dr1v90.c
> @@ -0,0 +1,135 @@
[...]
> +static const struct dr1v90_reset_map dr1v90_resets[] = {
> +	[RESET_OCM]		= { 0x74, BIT(4)},
[...]
> +	[RESET_NIC_HP0]		= { 0x78, BIT(0)},
[...]
> +	[RESET_USB0]		= { 0x7C, BIT(0)},

The registers 0x74, 0x78, and 0x7C are exclusively used for resets?

[...]
> +};
> +
> +static int dr1v90_reset_control_update(struct reset_controller_dev *rcdev,
> +				       unsigned long id, bool assert)
> +{
> +	struct dr1v90_reset_controller *rstc = to_dr1v90_reset_controller(rcdev);
> +	u32 offset = dr1v90_resets[id].offset;
> +	u32 bit = dr1v90_resets[id].bit;
> +	u32 reg;
> +
> +	reg = readl(rstc->base + offset);
> +	if (assert)
> +		reg &= ~bit;
> +	else
> +		reg |= bit;
> +	writel(reg, rstc->base + offset);

There should be a lock around this read-modify-write access.

regards
Philipp