linux-kernel - Re: [PATCH v6 5/6] reset: spacemit: define three more CCUs

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Message-ID: <a3febd3718397d7cf067e2ae637c2d633388f89f.camel@pengutronix.de>
Date: Thu, 08 May 2025 11:11:35 +0200
From: Philipp Zabel <p.zabel@...gutronix.de>
To: Alex Elder <elder@...cstar.com>, robh@...nel.org, krzk+dt@...nel.org, 
 conor+dt@...nel.org, mturquette@...libre.com, sboyd@...nel.org, 
 paul.walmsley@...ive.com, palmer@...belt.com, aou@...s.berkeley.edu,
 alex@...ti.fr,  dlan@...too.org
Cc: heylenay@....org, inochiama@...look.com, guodong@...cstar.com, 
 devicetree@...r.kernel.org, linux-clk@...r.kernel.org,
 spacemit@...ts.linux.dev,  linux-riscv@...ts.infradead.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH v6 5/6] reset: spacemit: define three more CCUs

On Di, 2025-05-06 at 16:06 -0500, Alex Elder wrote:
> Three more CCUs on the SpacemiT K1 SoC implement only resets, not clocks.
> Define these resets so they can be used.
> 
> Signed-off-by: Alex Elder <elder@...cstar.com>
> ---
>  drivers/clk/spacemit/ccu-k1.c | 24 ++++++++++++++++
>  drivers/reset/spacemit/k1.c   | 54 +++++++++++++++++++++++++++++++++++
>  include/soc/spacemit/ccu_k1.h | 30 +++++++++++++++++++
>  3 files changed, 108 insertions(+)
> 
> diff --git a/drivers/clk/spacemit/ccu-k1.c b/drivers/clk/spacemit/ccu-k1.c
> index 6b1845e899e5f..bddc83aff23cd 100644
> --- a/drivers/clk/spacemit/ccu-k1.c
> +++ b/drivers/clk/spacemit/ccu-k1.c
> @@ -939,6 +939,18 @@ static const struct spacemit_ccu_data k1_ccu_apmu_data = {
>  	.num		= ARRAY_SIZE(k1_ccu_apmu_hws),
>  };
>  
> +static const struct spacemit_ccu_data k1_ccu_rcpu_data = {

The /* No clocks in the RCPU CCU */ comment belongs here, instead of in
the reset driver.

I wonder though, if these units have no clocks, why are they called
CCUs? It doesn't make much sense to me to add their compatibles to the
ccu-k1 driver only to load the reset aux driver. Why not just add a
platform driver next to the aux driver in reset-spacemit.ko for these
three?

> +	.reset_name	= "rcpu-reset",
> +};
> +
> +static const struct spacemit_ccu_data k1_ccu_rcpu2_data = {
> +	.reset_name	= "rcpu2-reset",
> +};
> +
> +static const struct spacemit_ccu_data k1_ccu_apbc2_data = {
> +	.reset_name	= "apbc2-reset",
> +};
> +
>  static int spacemit_ccu_register(struct device *dev,
>  				 struct regmap *regmap,
>  				 struct regmap *lock_regmap,
> @@ -1106,6 +1118,18 @@ static const struct of_device_id of_k1_ccu_match[] = {
>  		.compatible	= "spacemit,k1-syscon-apmu",
>  		.data		= &k1_ccu_apmu_data,
>  	},
> +	{
> +		.compatible	= "spacemit,k1-syscon-rcpu",
> +		.data		= &k1_ccu_rcpu_data,
> +	},
> +	{
> +		.compatible	= "spacemit,k1-syscon-rcpu2",
> +		.data		= &k1_ccu_rcpu2_data,
> +	},
> +	{
> +		.compatible	= "spacemit,k1-syscon-apbc2",
> +		.data		= &k1_ccu_apbc2_data,
> +	},
>  	{ }
>  };
>  MODULE_DEVICE_TABLE(of, of_k1_ccu_match);
> diff --git a/drivers/reset/spacemit/k1.c b/drivers/reset/spacemit/k1.c
> index 19a34f151b214..27434a1928261 100644
> --- a/drivers/reset/spacemit/k1.c
> +++ b/drivers/reset/spacemit/k1.c
> @@ -137,6 +137,57 @@ static const struct ccu_reset_controller_data k1_apmu_reset_data = {
>  	.count		= ARRAY_SIZE(apmu_resets),
>  };
>  
> +static const struct ccu_reset_data rcpu_resets[] = {
> +	[RESET_RCPU_SSP0]	= RESET_DATA(RCPU_SSP0_CLK_RST,	0, BIT(0)),
> +	[RESET_RCPU_I2C0]	= RESET_DATA(RCPU_I2C0_CLK_RST,	0, BIT(0)),
> +	[RESET_RCPU_UART1]	= RESET_DATA(RCPU_UART1_CLK_RST, 0, BIT(0)),
> +	[RESET_RCPU_IR]		= RESET_DATA(RCPU_CAN_CLK_RST,	0, BIT(0)),
> +	[RESET_RCPU_CAN]	= RESET_DATA(RCPU_IR_CLK_RST,	0, BIT(0)),
> +	[RESET_RCPU_UART0]	= RESET_DATA(RCPU_UART0_CLK_RST, 0, BIT(0)),
> +	[RESET_RCPU_HDMI_AUDIO]	= RESET_DATA(AUDIO_HDMI_CLK_CTRL, 0, BIT(0)),
> +};
> +
> +static const struct ccu_reset_controller_data k1_rcpu_reset_data = {
> +	/* No clocks in the RCPU CCU */

This information is not useful in the reset driver.

regards
Philipp