linux-kernel - Re: [PATCH 2/2] irqchip/aspeed-scu-ic: Add support for AST2700 SCU interrupt controllers

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Message-ID: <20250805153908.GA1807801-robh@kernel.org>
Date: Tue, 5 Aug 2025 10:39:08 -0500
From: Rob Herring <robh@...nel.org>
To: Ryan Chen <ryan_chen@...eedtech.com>
Cc: Eddie James <eajames@...ux.ibm.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>, Joel Stanley <joel@....id.au>,
	Andrew Jeffery <andrew@...econstruct.com.au>,
	linux-aspeed@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
	devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 2/2] irqchip/aspeed-scu-ic: Add support for AST2700 SCU
 interrupt controllers

On Mon, Aug 04, 2025 at 01:34:45PM +0800, Ryan Chen wrote:
> The AST2700 SoC follows the multi-instance interrupt controller architecture
> introduced in the AST2600, where each SCU interrupt group (IC0–IC3) is treated
> as an independent interrupt domain.
> 
> Unlike the AST2600, which uses a combined register for interrupt enable and
> status bits, the AST2700 separates these into distinct registers: one for
> interrupt enable (IER) and another for interrupt status (ISR). This architectural
> change requires explicit handling of split registers for interrupt control.
> 
> - Register definitions and configuration for AST2700 SCU IC instances
>   (compatible: aspeed,ast2700-scu-ic0/1/2/3)
> - Initialization logic for handling split IER/ISR registers
> - Chained IRQ handling and mask/unmask logic
> - Table-driven registration using IRQCHIP_DECLARE per compatible
> 
> Signed-off-by: Ryan Chen <ryan_chen@...eedtech.com>
> ---
>  drivers/irqchip/irq-aspeed-scu-ic.c | 240 ++++++++++++++++++++++------
>  1 file changed, 195 insertions(+), 45 deletions(-)
> 
> diff --git a/drivers/irqchip/irq-aspeed-scu-ic.c b/drivers/irqchip/irq-aspeed-scu-ic.c
> index 1c7045467c48..b6f3ba269c5b 100644
> --- a/drivers/irqchip/irq-aspeed-scu-ic.c
> +++ b/drivers/irqchip/irq-aspeed-scu-ic.c
> @@ -1,6 +1,6 @@
>  // SPDX-License-Identifier: GPL-2.0-or-later
>  /*
> - * Aspeed AST24XX, AST25XX, and AST26XX SCU Interrupt Controller
> + * Aspeed AST24XX, AST25XX, AST26XX, AST27XX SCU Interrupt Controller
>   * Copyright 2019 IBM Corporation
>   *
>   * Eddie James <eajames@...ux.ibm.com>
> @@ -34,11 +34,42 @@
>  	GENMASK(5, ASPEED_AST2600_SCU_IC1_SHIFT)
>  #define ASPEED_AST2600_SCU_IC1_NUM_IRQS	2
>  
> +#define ASPEED_AST2700_SCU_IC0_EN_REG	0x1d0
> +#define ASPEED_AST2700_SCU_IC0_STS_REG	0x1d4
> +#define ASPEED_AST2700_SCU_IC0_SHIFT	0
> +#define ASPEED_AST2700_SCU_IC0_ENABLE	\
> +	GENMASK(3, ASPEED_AST2700_SCU_IC0_SHIFT)
> +#define ASPEED_AST2700_SCU_IC0_NUM_IRQS	4
> +
> +#define ASPEED_AST2700_SCU_IC1_EN_REG	0x1e0
> +#define ASPEED_AST2700_SCU_IC1_STS_REG	0x1e4
> +#define ASPEED_AST2700_SCU_IC1_SHIFT	0
> +#define ASPEED_AST2700_SCU_IC1_ENABLE	\
> +	GENMASK(3, ASPEED_AST2700_SCU_IC1_SHIFT)
> +#define ASPEED_AST2700_SCU_IC1_NUM_IRQS	4
> +
> +#define ASPEED_AST2700_SCU_IC2_EN_REG	0x104
> +#define ASPEED_AST2700_SCU_IC2_STS_REG	0x100
> +#define ASPEED_AST2700_SCU_IC2_SHIFT	0
> +#define ASPEED_AST2700_SCU_IC2_ENABLE	\
> +	GENMASK(3, ASPEED_AST2700_SCU_IC2_SHIFT)
> +#define ASPEED_AST2700_SCU_IC2_NUM_IRQS	4
> +
> +#define ASPEED_AST2700_SCU_IC3_EN_REG	0x10c
> +#define ASPEED_AST2700_SCU_IC3_STS_REG	0x108
> +#define ASPEED_AST2700_SCU_IC3_SHIFT	0
> +#define ASPEED_AST2700_SCU_IC3_ENABLE	\
> +	GENMASK(1, ASPEED_AST2700_SCU_IC3_SHIFT)
> +#define ASPEED_AST2700_SCU_IC3_NUM_IRQS	2
> +

The reason for ic0/ic1 compatibles before was the enable field was 
different. Now it's at least at the same shift. Do you really need a 
different value for IC3? 

The register addresses should come from "reg". I don't understand why 
they are hardcoded in the driver.

Rob