Re: [PATCH] mfd: loongson-se: Add multi-node support

[Lee Jones <lee@kernel.org>]

On Thu, 26 Feb 2026, Qunqin Zhao wrote:

> On the Loongson platform, each node is equipped with a security engine
> device. However, due to a hardware flaw, only the device on node 0 can
> trigger interrupts. Therefore, interrupts from other nodes are forwarded
> by node 0. We need to check in the interrupt handler of node 0 whether
> this interrupt is intended for other nodes.
> 
> Signed-off-by: Qunqin Zhao <zhaoqunqin@loongson.cn>
> ---
>  drivers/mfd/loongson-se.c       | 38 +++++++++++++++++++++++++++------
>  include/linux/mfd/loongson-se.h |  3 +++
>  2 files changed, 35 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/mfd/loongson-se.c b/drivers/mfd/loongson-se.c
> index 3902ba377..40e18c212 100644
> --- a/drivers/mfd/loongson-se.c
> +++ b/drivers/mfd/loongson-se.c
> @@ -37,6 +37,9 @@ struct loongson_se_controller_cmd {
>  	u32 info[7];
>  };
>  
> +static DECLARE_COMPLETION(node0);
> +static struct loongson_se *se_node[SE_MAX_NODES];

Really not keen on global variables.

Why are they _needed_?

>  static int loongson_se_poll(struct loongson_se *se, u32 int_bit)
>  {
>  	u32 status;
> @@ -133,8 +136,8 @@ EXPORT_SYMBOL_GPL(loongson_se_init_engine);
>  static irqreturn_t se_irq_handler(int irq, void *dev_id)
>  {
>  	struct loongson_se *se = dev_id;
> -	u32 int_status;
> -	int id;
> +	u32 int_status, node_irq = 0;
> +	int id, node;
>  
>  	spin_lock(&se->dev_lock);
>  
> @@ -147,6 +150,11 @@ static irqreturn_t se_irq_handler(int irq, void *dev_id)
>  		writel(SE_INT_CONTROLLER, se->base + SE_S2LINT_CL);
>  	}
>  
> +	if (int_status & SE_INT_OTHER_NODE) {
> +		int_status &= ~SE_INT_OTHER_NODE;
> +		node_irq = 1;
> +	}
> +
>  	/* For engines */
>  	while (int_status) {
>  		id = __ffs(int_status);
> @@ -157,6 +165,14 @@ static irqreturn_t se_irq_handler(int irq, void *dev_id)
>  
>  	spin_unlock(&se->dev_lock);
>  
> +	if (node_irq) {
> +		writel(SE_INT_OTHER_NODE, se->base + SE_S2LINT_CL);
> +		for (node = 1; node < SE_MAX_NODES; node++) {
> +			if (se_node[node])
> +				se_irq_handler(irq, se_node[node]);
> +		}
> +	}
> +
>  	return IRQ_HANDLED;
>  }
>  
> @@ -189,6 +205,7 @@ static int loongson_se_probe(struct platform_device *pdev)
>  	struct loongson_se *se;
>  	int nr_irq, irq, err, i;
>  	dma_addr_t paddr;
> +	int node = dev_to_node(dev);
>  
>  	se = devm_kmalloc(dev, sizeof(*se), GFP_KERNEL);
>  	if (!se)
> @@ -213,9 +230,16 @@ static int loongson_se_probe(struct platform_device *pdev)
>  
>  	writel(SE_INT_ALL, se->base + SE_S2LINT_EN);
>  
> -	nr_irq = platform_irq_count(pdev);
> -	if (nr_irq <= 0)
> -		return -ENODEV;
> +	if (node == 0 || node == NUMA_NO_NODE) {
> +		nr_irq = platform_irq_count(pdev);
> +		if (nr_irq <= 0)
> +			return -ENODEV;
> +	} else {
> +		/* Only the device on node 0 can trigger interrupts */
> +		nr_irq = 0;
> +		wait_for_completion_interruptible(&node0);
> +		se_node[node] = se;
> +	}
>  
>  	for (i = 0; i < nr_irq; i++) {
>  		irq = platform_get_irq(pdev, i);
> @@ -228,7 +252,9 @@ static int loongson_se_probe(struct platform_device *pdev)
>  	if (err)
>  		return err;
>  
> -	return devm_mfd_add_devices(dev, PLATFORM_DEVID_NONE, engines,
> +	complete_all(&node0);
> +
> +	return devm_mfd_add_devices(dev, PLATFORM_DEVID_AUTO, engines,
>  				    ARRAY_SIZE(engines), NULL, 0, NULL);
>  }
>  
> diff --git a/include/linux/mfd/loongson-se.h b/include/linux/mfd/loongson-se.h
> index 07afa0c25..a80e06eb0 100644
> --- a/include/linux/mfd/loongson-se.h
> +++ b/include/linux/mfd/loongson-se.h
> @@ -20,6 +20,9 @@
>  
>  #define SE_INT_ALL			0xffffffff
>  #define SE_INT_CONTROLLER		BIT(0)
> +#define SE_INT_OTHER_NODE		BIT(31)
> +
> +#define SE_MAX_NODES			8
>  
>  #define SE_ENGINE_MAX			16
>  #define SE_ENGINE_RNG			1
> -- 
> 2.47.2
> 

-- 
Lee Jones [李琼斯]