Re: [PATCH v8 3/4] irqchip:create irq domain for each mbigen device

[Marc Zyngier]

On 06/11/15 08:28, MaJun wrote:
> From: Ma Jun <majun258@xxxxxxxxxx>
> 
> 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@xxxxxxxxxx>
> ---
>  drivers/irqchip/irq-mbigen.c |  163 ++++++++++++++++++++++++++++++++++++++++++
>  1 files changed, 163 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/irqchip/irq-mbigen.c b/drivers/irqchip/irq-mbigen.c
> index 25e4000..71291cb 100644
> --- a/drivers/irqchip/irq-mbigen.c
> +++ b/drivers/irqchip/irq-mbigen.c
> @@ -16,27 +16,176 @@
>   * 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
> +
> +/* 16 irqs (Pin0-pin15) are reserved for each mbigen chip */
> +#define RESERVED_IRQ_PER_MBIGEN_CHIP	16
> +
> +/**
> + * 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.
>   *
>   * @pdev:		pointer to the platform device structure of mbigen chip.
>   * @base:		mapped address of this mbigen chip.
> + * @domain:		pointer to the irq domain
>   */
>  struct mbigen_device {
>  	struct platform_device	*pdev;
>  	void __iomem		*base;
> +	struct irq_domain	*domain;
> +};
> +
> +/**
> + * struct mbigen_irq_data - private data of each irq
> + *
> + * @base:		mapped address of mbigen chip
> + * @reg_vec:		addr offset of interrupt vector register.
> + */
> +struct mbigen_irq_data {
> +	void __iomem		*base;
> +	unsigned int		reg_vec;
> +};
> +
> +static inline int get_mbigen_vec_reg(u32 nid, u32 offset)
> +{
> +	return (offset * 4) + nid * MBIGEN_NODE_OFFSET
> +			+ REG_MBIGEN_VEC_OFFSET;
> +}
> +
> +static struct irq_chip mbigen_irq_chip = {
> +	.name =			"mbigen-v2",
> +};
> +
> +static void mbigen_write_msg(struct msi_desc *desc, struct msi_msg *msg)
> +{
> +	struct mbigen_irq_data *mgn_irq_data = irq_get_chip_data(desc->irq);
> +	u32 val;
> +
> +	val = readl_relaxed(mgn_irq_data->reg_vec + mgn_irq_data->base);
> +
> +	val &= ~(IRQ_EVENT_ID_MASK << IRQ_EVENT_ID_SHIFT);
> +	val |= (msg->data << IRQ_EVENT_ID_SHIFT);
> +
> +	writel_relaxed(val, mgn_irq_data->reg_vec + mgn_irq_data->base);
> +}
> +
> +static struct mbigen_irq_data *set_mbigen_irq_data(int hwirq)
> +{
> +	struct mbigen_irq_data *datap;
> +	unsigned int nid, pin_offset;
> +
> +	datap = kzalloc(sizeof(*datap), GFP_KERNEL);
> +	if (!datap)
> +		return NULL;
> +
> +	/* get the mbigen node number */
> +	nid = (hwirq - RESERVED_IRQ_PER_MBIGEN_CHIP) / IRQS_PER_MBIGEN_NODE + 1;
> +
> +	pin_offset = (hwirq - RESERVED_IRQ_PER_MBIGEN_CHIP)
> +					% IRQS_PER_MBIGEN_NODE;
> +
> +	datap->reg_vec = get_mbigen_vec_reg(nid, pin_offset);
> +	return datap;
> +}

I really don't like the fact that you are allocating per a interrupt
structure to cache something that is essentially a set of constants. You
can derive everything from hwirq and work out the scaling at runtime
(the compiler should be pretty smart at optimizing those, ending up
being much cheaper than fetching random data from memory).

All you have to do is cache the base address of your mbichip in the
chip_data field.

For example, your reg_vec usage:

static inline unsigned int get_mbigen_vec_offset(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;
}

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_mgigen_vec_offset(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);
}

No allocation, and GCC should be able to turn get_mbigen_vec_offset into
a nice bunch of shifts and masks. Same goes for the additional stuff you
have in patch #4.

> +
> +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];
> +		*type = fwspec->param[1] & IRQ_TYPE_SENSE_MASK;
> +
> +		return 0;
> +	}
> +	return -EINVAL;
> +}
> +
> +static int mbigen_irq_domain_alloc(struct irq_domain *domain,
> +					unsigned int virq,
> +					unsigned int nr_irqs,
> +					void *args)
> +{
> +	struct irq_fwspec *fwspec = args;
> +	irq_hw_number_t hwirq;
> +	unsigned int type;
> +	struct mbigen_device *mgn_chip;
> +	struct mbigen_irq_data *mgn_irq_data;
> +	int i, err;
> +
> +	err = mbigen_domain_translate(domain, fwspec, &hwirq, &type);
> +	if (err)
> +		return err;
> +
> +	err = platform_msi_domain_alloc(domain, virq, nr_irqs);
> +	if (err)
> +		return err;
> +
> +	/* set related information of this irq */
> +	mgn_irq_data = set_mbigen_irq_data(hwirq);
> +	if (!mgn_irq_data)
> +		return err;

You can now get rid of this.

> +
> +	mgn_chip = platform_msi_get_host_data(domain);
> +	mgn_irq_data->base = mgn_chip->base;
> +
> +	for (i = 0; i < nr_irqs; i++)
> +		irq_domain_set_hwirq_and_chip(domain, virq + i, hwirq + i,
> +				      &mbigen_irq_chip, mgn_irq_data);

and just store the base.

> +
> +	return 0;
> +}
> +
> +static void mbigen_domain_free(struct irq_domain *domain, unsigned int virq,
> +			       unsigned int nr_irqs)
> +{
> +	struct irq_data *d = irq_domain_get_irq_data(domain, virq);
> +	struct mbigen_irq_data *mgn_irq_data = irq_data_get_irq_chip_data(d);
> +
> +	kfree(mgn_irq_data);
> +	irq_domain_free_irqs_common(domain, virq, nr_irqs);
> +}
> +
> +static struct irq_domain_ops mbigen_domain_ops = {
> +	.translate	= mbigen_domain_translate,
> +	.alloc		= mbigen_irq_domain_alloc,
> +	.free		= mbigen_domain_free,
>  };
>  
>  static int mbigen_device_probe(struct platform_device *pdev)
>  {
>  	struct mbigen_device *mgn_chip;
> +	struct irq_domain *domain;
> +	u32 num_msis;
>  
>  	mgn_chip = devm_kzalloc(&pdev->dev, sizeof(*mgn_chip), GFP_KERNEL);
>  	if (!mgn_chip)
> @@ -45,6 +194,20 @@ static int mbigen_device_probe(struct platform_device *pdev)
>  	mgn_chip->pdev = pdev;
>  	mgn_chip->base = of_iomap(pdev->dev.of_node, 0);
>  
> +	/* If there is no "num-msi" property, assume 64... */
> +	if (of_property_read_u32(pdev->dev.of_node, "num-msis", &num_msis) < 0)
> +		num_msis = 64;
> +

See my comment about patch #2.

> +	domain = platform_msi_create_device_domain(&pdev->dev, num_msis,
> +							mbigen_write_msg,
> +							&mbigen_domain_ops,
> +							mgn_chip);
> +
> +	if (!domain)
> +		return -ENOMEM;
> +
> +	mgn_chip->domain = domain;
> +
>  	platform_set_drvdata(pdev, mgn_chip);
>  
>  	return 0;
> 

I'll look at the rest tomorrow.

Thanks,

	M.
-- 
Jazz is not dead. It just smells funny...
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