Re: [PATCH v9 3/4] irqchip:create irq domain for each mbigen device

[Mark Rutland <mark.rutland@arm.com>]

On Mon, Nov 23, 2015 at 11:15:12AM +0800, MaJun wrote:
> From: Ma Jun <majun258@huawei.com>
> 
> For peripheral devices which connect to mbigen,mbigen is a interrupt
> controller. So, we create irq domain for each mbigen device and add
> mbigen irq domain into irq hierarchy structure.
> 
> Signed-off-by: Ma Jun <majun258@huawei.com>
> ---
>  drivers/irqchip/irq-mbigen.c |  119 ++++++++++++++++++++++++++++++++++++++++++
>  1 files changed, 119 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/irqchip/irq-mbigen.c b/drivers/irqchip/irq-mbigen.c
> index 9f036c2..81ae61f 100644
> --- a/drivers/irqchip/irq-mbigen.c
> +++ b/drivers/irqchip/irq-mbigen.c
> @@ -16,13 +16,36 @@
>   * along with this program.  If not, see <http://www.gnu.org/licenses/>.
>   */
>  
> +#include <linux/interrupt.h>
> +#include <linux/irqchip.h>
>  #include <linux/module.h>
> +#include <linux/msi.h>
>  #include <linux/of_address.h>
>  #include <linux/of_irq.h>
>  #include <linux/of_platform.h>
>  #include <linux/platform_device.h>
>  #include <linux/slab.h>
>  
> +/* Interrupt numbers per mbigen node supported */
> +#define IRQS_PER_MBIGEN_NODE		128
> +
> +/* 64 irqs (Pin0-pin63) are reserved for each mbigen chip */
> +#define RESERVED_IRQ_PER_MBIGEN_CHIP	64
> +
> +/**
> + * In mbigen vector register
> + * bit[21:12]:	event id value
> + * bit[11:0]:	device id
> + */
> +#define IRQ_EVENT_ID_SHIFT		12
> +#define IRQ_EVENT_ID_MASK		0x3ff
> +
> +/* register range of each mbigen node */
> +#define MBIGEN_NODE_OFFSET		0x1000
> +
> +/* offset of vector register in mbigen node */
> +#define REG_MBIGEN_VEC_OFFSET		0x200
> +
>  /**
>   * struct mbigen_device - holds the information of mbigen device.
>   *
> @@ -34,10 +57,94 @@ struct mbigen_device {
>  	void __iomem		*base;
>  };
>  
> +static inline unsigned int get_mbigen_vec_reg(irq_hw_number_t hwirq)
> +{
> +	unsigned int nid, pin;
> +
> +	hwirq -= RESERVED_IRQ_PER_MBIGEN_CHIP;
> +	nid = hwirq / IRQS_PER_MBIGEN_NODE + 1;
> +	pin = hwirq % IRQS_PER_MBIGEN_NODE;
> +
> +	return pin * 4 + nid * MBIGEN_NODE_OFFSET
> +			+ REG_MBIGEN_VEC_OFFSET;
> +}

Ok. So your "global" pin id is "global" per mbigen chip.

I think it may make more sense to have separate nid and pin fields in
your interrupt-specifier, e.g. interrupt = <1 3 x> for nid 1, pin 3.

That's easier for someone to check against a datasheet that describes
the nid and pin rather than the global number space you've come up with,
and also makes it impossible to describe the reserved IRQs.

> +
> +static struct irq_chip mbigen_irq_chip = {
> +	.name =			"mbigen-v2",
> +};
> +
> +static void mbigen_write_msg(struct msi_desc *desc, struct msi_msg *msg)
> +{
> +	struct irq_data *d = irq_get_irq_data(desc->irq);
> +	void __iomem *base = d->chip_data;
> +	u32 val;
> +
> +	base += get_mbigen_vec_reg(d->hwirq);
> +	val = readl_relaxed(base);
> +
> +	val &= ~(IRQ_EVENT_ID_MASK << IRQ_EVENT_ID_SHIFT);
> +	val |= (msg->data << IRQ_EVENT_ID_SHIFT);
> +
> +	writel_relaxed(val, base);
> +}
> +
> +static int mbigen_domain_translate(struct irq_domain *d,
> +				    struct irq_fwspec *fwspec,
> +				    unsigned long *hwirq,
> +				    unsigned int *type)
> +{
> +	if (is_of_node(fwspec->fwnode)) {
> +		if (fwspec->param_count != 2)
> +			return -EINVAL;
> +
> +		*hwirq = fwspec->param[0];

You should validate the hwirq here. For instance, we never expect a
hwirq < RESERVED_IRQ_PER_MBIGEN_CHIP here.

> +		*type = fwspec->param[1] & IRQ_TYPE_SENSE_MASK;

Don't mask out bits you don't expect to be set. Validate that they
aren't set and complain if they are.

> @@ -50,6 +157,18 @@ static int mbigen_device_probe(struct platform_device *pdev)
>  	if (IS_ERR(mgn_chip->base))
>  		return PTR_ERR(mgn_chip->base);
>  
> +	/* If there is no "num-msis" property, assume 64... */
> +	if (of_property_read_u32(pdev->dev.of_node, "num-msis", &num_msis) < 0)
> +		num_msis = 64;

The "num-msis" property was mandatory in the binding. We shouldn't need
the fallback.

It it is missing, print an error, and abort probing here.

Thanks,
Mark.