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

From: [email-masked] (majun)
Date: Wed, 16 Dec 2015 09:57:12 -0500

Hi Marc and Mark:

On 2015/12/11 10:42, Mark Rutland wrote:
> On Mon, Nov 23, 2015 at 11:15:12AM +0800, MaJun wrote:
>> From: Ma Jun <[email-masked]>
>>
>> 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 <[email-masked]>
>> ---
>>  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.

right.

> 
> 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.

There are no nid and pin fields in our new datasheet now.
All we can see is hardware pin number.
So adding nid and pin fields makes the people more confused about using
mbigen.

Further more, "pin" is not a good variable name. I should name it as
"pin_offset" or just"offset" to present the interrupt pin offset to mbigen node.

> 
>> +
>> +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.

Yes, I also think I need to check the hwirq input value.
The hwirq should be:
hwirq > RESERVED_IRQ_PER_MBIGEN_CHIP && hwirq < MAXIMUM_INTERRUPT_NUMBER

> 
>> +		*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.
> 

I referred Marc's dummy driver when coding this function.

Marc, do you have any different comment about these two parts.

>> @@ -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.
> 

Yes you are right.

Thanks
MaJun

> Thanks,
> Mark.
> .