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Date:   Fri, 10 May 2019 19:12:18 +0100
From:   Marc Zyngier <marc.zyngier@....com>
To:     Guo Ren <guoren@...nel.org>
Cc:     tglx@...utronix.de, robh+dt@...nel.org,
        linux-kernel@...r.kernel.org, Guo Ren <ren_guo@...ky.com>
Subject: Re: [PATCH V2 4/7] irqchip/irq-csky-mpintc: Add triger type and priority

On Fri, 10 May 2019 09:25:10 +0100,
Guo Ren <guoren@...nel.org> wrote:
> 
> Thx Marc,
> 
> Sorry for late reply:
> 
> On Mon, Feb 18, 2019 at 02:38:23PM +0000, Marc Zyngier wrote:
> > On Mon, 18 Feb 2019 10:04:40 +0800
> > guoren@...nel.org wrote:
> > 
> > > From: Guo Ren <ren_guo@...ky.com>
> > > 
> > > Support 4 triger types:
> > >  - IRQ_TYPE_LEVEL_HIGH
> > >  - IRQ_TYPE_LEVEL_LOW
> > >  - IRQ_TYPE_EDGE_RISING
> > >  - IRQ_TYPE_EDGE_FALLING
> > > 
> > > Support 0-255 priority setting for each irq.
> > > 
> > > Changelog:
> > >  - Fixup this_cpu_read() preempted problem.
> > >  - Optimize the coding style.
> > > 
> > > Signed-off-by: Guo Ren <ren_guo@...ky.com>
> > > Cc: Marc Zyngier <marc.zyngier@....com>
> > > ---
> > >  drivers/irqchip/irq-csky-mpintc.c | 105 +++++++++++++++++++++++++++++++++++++-
> > >  1 file changed, 104 insertions(+), 1 deletion(-)
> > > 
> > > diff --git a/drivers/irqchip/irq-csky-mpintc.c b/drivers/irqchip/irq-csky-mpintc.c
> > > index 99d3f3f..07a3752 100644
> > > --- a/drivers/irqchip/irq-csky-mpintc.c
> > > +++ b/drivers/irqchip/irq-csky-mpintc.c
> > > @@ -17,6 +17,7 @@
> > >  #include <asm/reg_ops.h>
> > >  
> > >  static struct irq_domain *root_domain;
> > > +
> > >  static void __iomem *INTCG_base;
> > >  static void __iomem *INTCL_base;
> > >  
> > > @@ -29,9 +30,12 @@ static void __iomem *INTCL_base;
> > >  
> > >  #define INTCG_ICTLR	0x0
> > >  #define INTCG_CICFGR	0x100
> > > +#define INTCG_CIPRTR	0x200
> > >  #define INTCG_CIDSTR	0x1000
> > >  
> > >  #define INTCL_PICTLR	0x0
> > > +#define INTCL_CFGR	0x14
> > > +#define INTCL_PRTR	0x20
> > >  #define INTCL_SIGR	0x60
> > >  #define INTCL_RDYIR	0x6c
> > >  #define INTCL_SENR	0xa0
> > > @@ -40,6 +44,51 @@ static void __iomem *INTCL_base;
> > >  
> > >  static DEFINE_PER_CPU(void __iomem *, intcl_reg);
> > >  
> > > +static unsigned long *__trigger;
> > > +static unsigned long *__priority;
> > > +
> > > +#define IRQ_OFFSET(irq) ((irq < COMM_IRQ_BASE) ? irq : (irq - COMM_IRQ_BASE))
> > > +
> > > +#define TRIG_BYTE_OFFSET(i)	((((i) * 2) / 32) * 4)
> > > +#define TRIG_BIT_OFFSET(i)	 (((i) * 2) % 32)
> > > +
> > > +#define PRI_BYTE_OFFSET(i)	((((i) * 8) / 32) * 4)
> > > +#define PRI_BIT_OFFSET(i)	 (((i) * 8) % 32)
> > > +
> > > +#define TRIG_VAL(trigger, irq)	(trigger << TRIG_BIT_OFFSET(IRQ_OFFSET(irq)))
> > > +#define TRIG_VAL_MSK(irq)	    (~(3 << TRIG_BIT_OFFSET(IRQ_OFFSET(irq))))
> > > +#define PRI_VAL(priority, irq)	(priority << PRI_BIT_OFFSET(IRQ_OFFSET(irq)))
> > > +#define PRI_VAL_MSK(irq)	  (~(0xff << PRI_BIT_OFFSET(IRQ_OFFSET(irq))))
> > > +
> > > +#define TRIG_BASE(irq) \
> > > +	(TRIG_BYTE_OFFSET(IRQ_OFFSET(irq)) + ((irq < COMM_IRQ_BASE) ? \
> > > +	(this_cpu_read(intcl_reg) + INTCL_CFGR) : (INTCG_base + INTCG_CICFGR)))
> > > +
> > > +#define PRI_BASE(irq) \
> > > +	(PRI_BYTE_OFFSET(IRQ_OFFSET(irq)) + ((irq < COMM_IRQ_BASE) ? \
> > > +	(this_cpu_read(intcl_reg) + INTCL_PRTR) : (INTCG_base + INTCG_CIPRTR)))
> > > +
> > > +static DEFINE_SPINLOCK(setup_lock);
> > > +static void setup_trigger_priority(unsigned long irq, unsigned long trigger,
> > > +				   unsigned long priority)
> > > +{
> > > +	unsigned int tmp;
> > > +
> > > +	spin_lock(&setup_lock);
> > > +
> > > +	/* setup trigger */
> > > +	tmp = readl_relaxed(TRIG_BASE(irq)) & TRIG_VAL_MSK(irq);
> > > +
> > > +	writel_relaxed(tmp | TRIG_VAL(trigger, irq), TRIG_BASE(irq));
> > > +
> > > +	/* setup priority */
> > > +	tmp = readl_relaxed(PRI_BASE(irq)) & PRI_VAL_MSK(irq);
> > > +
> > > +	writel_relaxed(tmp | PRI_VAL(priority, irq), PRI_BASE(irq));
> > > +
> > > +	spin_unlock(&setup_lock);
> > > +}
> > > +
> > >  static void csky_mpintc_handler(struct pt_regs *regs)
> > >  {
> > >  	void __iomem *reg_base = this_cpu_read(intcl_reg);
> > > @@ -52,6 +101,9 @@ static void csky_mpintc_enable(struct irq_data *d)
> > >  {
> > >  	void __iomem *reg_base = this_cpu_read(intcl_reg);
> > >  
> > > +	setup_trigger_priority(d->hwirq, __trigger[d->hwirq],
> > > +				 __priority[d->hwirq]);
> > > +
> > >  	writel_relaxed(d->hwirq, reg_base + INTCL_SENR);
> > >  }
> > >  
> > > @@ -69,6 +121,28 @@ static void csky_mpintc_eoi(struct irq_data *d)
> > >  	writel_relaxed(d->hwirq, reg_base + INTCL_CACR);
> > >  }
> > >  
> > > +static int csky_mpintc_set_type(struct irq_data *d, unsigned int type)
> > > +{
> > > +	switch (type & IRQ_TYPE_SENSE_MASK) {
> > > +	case IRQ_TYPE_LEVEL_HIGH:
> > > +		__trigger[d->hwirq] = 0;
> > > +		break;
> > > +	case IRQ_TYPE_LEVEL_LOW:
> > > +		__trigger[d->hwirq] = 1;
> > > +		break;
> > > +	case IRQ_TYPE_EDGE_RISING:
> > > +		__trigger[d->hwirq] = 2;
> > > +		break;
> > > +	case IRQ_TYPE_EDGE_FALLING:
> > > +		__trigger[d->hwirq] = 3;
> > > +		break;
> > > +	default:
> > > +		return -EINVAL;
> > > +	}
> > > +
> > > +	return 0;
> > > +}
> > > +
> > >  #ifdef CONFIG_SMP
> > >  static int csky_irq_set_affinity(struct irq_data *d,
> > >  				 const struct cpumask *mask_val,
> > > @@ -101,6 +175,7 @@ static struct irq_chip csky_irq_chip = {
> > >  	.irq_eoi	= csky_mpintc_eoi,
> > >  	.irq_enable	= csky_mpintc_enable,
> > >  	.irq_disable	= csky_mpintc_disable,
> > > +	.irq_set_type	= csky_mpintc_set_type,
> > >  #ifdef CONFIG_SMP
> > >  	.irq_set_affinity = csky_irq_set_affinity,
> > >  #endif
> > > @@ -121,9 +196,29 @@ static int csky_irqdomain_map(struct irq_domain *d, unsigned int irq,
> > >  	return 0;
> > >  }
> > >  
> > > +static int csky_irq_domain_xlate_cells(struct irq_domain *d,
> > > +		struct device_node *ctrlr, const u32 *intspec,
> > > +		unsigned int intsize, unsigned long *out_hwirq,
> > > +		unsigned int *out_type)
> > > +{
> > > +	if (WARN_ON(intsize < 1))
> > > +		return -EINVAL;
> > > +
> > > +	*out_hwirq = intspec[0];
> > > +	if (intsize > 1)
> > > +		*out_type = intspec[1] & IRQ_TYPE_SENSE_MASK;
> > > +	else
> > > +		*out_type = IRQ_TYPE_NONE;
> > 
> > What does IRQ_TYPE_NONE mean in this context? Shouldn't it actually be
> > whatever the HW defaults to? Or even better, whatever was expected in
> > the previous definition of the DT binding?
> Yes, it shouldn't use IRQ_TYPE_NONE and I'll use
> > IRQ_TYPE_LEVEL_HIGH.

I think you should use what the DT gives you and nothing else, unless
there is some backward compatibility scheme you want to support.

> 
> > 
> > > +
> > > +	if (intsize > 2)
> > > +		__priority[*out_hwirq] = intspec[2];
> > 
> > And what is the used priority in this case?
> C-SKY MPINTC could support interrupt's priority and this will be set in
> INTCG_CIPRTR register. It is set in csky_mpintc_enable function.
>
> > 
> > > +
> > > +	return 0;
> > > +}
> > > +
> > >  static const struct irq_domain_ops csky_irqdomain_ops = {
> > >  	.map	= csky_irqdomain_map,
> > > -	.xlate	= irq_domain_xlate_onecell,
> > > +	.xlate	= csky_irq_domain_xlate_cells,
> > >  };
> > >  
> > >  #ifdef CONFIG_SMP
> > > @@ -157,6 +252,14 @@ csky_mpintc_init(struct device_node *node, struct device_node *parent)
> > >  	if (ret < 0)
> > >  		nr_irq = INTC_IRQS;
> > >  
> > > +	__priority = kcalloc(nr_irq, sizeof(unsigned long), GFP_KERNEL);
> > > +	if (__priority == NULL)
> > > +		return -ENXIO;
> > > +
> > > +	__trigger  = kcalloc(nr_irq, sizeof(unsigned long), GFP_KERNEL);
> > > +	if (__trigger == NULL)
> > > +		return -ENXIO;
> > 
> > Maybe you should consider initializing these arrays to something that
> > makes sense for the case where the DT doesn't carry this information
> > (which is 100% of the DTs up to this point).
> Yes, and zero is enough.
> 
> /**
>  * kcalloc - allocate memory for an array. The memory is set to zero.
>  * @n: number of elements.
>  * @size: element size.
>  * @flags: the type of memory to allocate (see kmalloc).
>  */
> static inline void *kcalloc(size_t n, size_t size, gfp_t flags)
> {
> 	return kmalloc_array(n, size, flags | __GFP_ZERO);
> }

Trust me, I have a rather precise idea of how kcalloc works, and I
have a copy of the kernel source handy, so no need to paste it in an
email.

My question was about the default values: Everything gets a default
priority of zero, and nothing seem to set it to another value
either. So why do we have this allocation anyway?

	M.

-- 
Jazz is not dead, it just smell funny.

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