Re: [PATCH v2 02/10] irqchip: add irqchip driver for nuc900

[Wan Zongshun <vw@iommu.org>]

On 2016年07月14日 21:54, Jason Cooper wrote:
> Hi Wan Zongshun,
>
> On Thu, Jul 14, 2016 at 11:36:53AM +0800, Wan Zongshun wrote:
>> On 2016年07月14日 04:09, Jason Cooper wrote:
>>> On Sun, Jul 10, 2016 at 03:27:22PM +0800, Wan Zongshun wrote:
>>>> This patch is to add irqchip driver support for nuc900 plat,
>>>> current this driver only supports nuc970 SoC.
>>>>
>>>> Signed-off-by: Wan Zongshun <mcuos.com@gmail.com>
>>>> ---
>>>>   arch/arm/mach-w90x900/include/mach/irqs.h |   5 +
>>>>   drivers/irqchip/Makefile                  |   1 +
>>>>   drivers/irqchip/irq-nuc900.c              | 150 ++++++++++++++++++++++++++++++
>>>>   3 files changed, 156 insertions(+)
>>>>   create mode 100644 drivers/irqchip/irq-nuc900.c
>>>>
>>>> diff --git a/arch/arm/mach-w90x900/include/mach/irqs.h b/arch/arm/mach-w90x900/include/mach/irqs.h
>>>> index 9d5cba3..3b035c6 100644
>>>> --- a/arch/arm/mach-w90x900/include/mach/irqs.h
>>>> +++ b/arch/arm/mach-w90x900/include/mach/irqs.h
>>>> @@ -59,7 +59,12 @@
>>>>   #define IRQ_KPI		W90X900_IRQ(29)
>>>>   #define IRQ_P2SGROUP	W90X900_IRQ(30)
>>>>   #define IRQ_ADC		W90X900_IRQ(31)
>>>> +
>>>> +#if !defined(CONFIG_SOC_NUC900)
>>>>   #define NR_IRQS		(IRQ_ADC+1)
>>>> +#else
>>>> +#define NR_IRQS		62
>>>> +#endif
>>>
>>> Arnd already covered this...
>>>
>>>>
>>>>   /*for irq group*/
>>>>
>>>> diff --git a/drivers/irqchip/Makefile b/drivers/irqchip/Makefile
>>>> index 38853a1..9ccd5af8a 100644
>>>> --- a/drivers/irqchip/Makefile
>>>> +++ b/drivers/irqchip/Makefile
>>>> @@ -69,3 +69,4 @@ obj-$(CONFIG_PIC32_EVIC)		+= irq-pic32-evic.o
>>>>   obj-$(CONFIG_MVEBU_ODMI)		+= irq-mvebu-odmi.o
>>>>   obj-$(CONFIG_LS_SCFG_MSI)		+= irq-ls-scfg-msi.o
>>>>   obj-$(CONFIG_EZNPS_GIC)			+= irq-eznps.o
>>>> +obj-$(CONFIG_SOC_NUC970)		+= irq-nuc900.o
>>>> diff --git a/drivers/irqchip/irq-nuc900.c b/drivers/irqchip/irq-nuc900.c
>>>> new file mode 100644
>>>> index 0000000..c4b2e39
>>>> --- /dev/null
>>>> +++ b/drivers/irqchip/irq-nuc900.c
>>>> @@ -0,0 +1,150 @@
>>>> +/*
>>>> + * Copyright 2016 Wan Zongshun <mcuos.com@gmail.com>
>>>> + *
>>>> + * The code contained herein is licensed under the GNU General Public
>>>> + * License. You may obtain a copy of the GNU General Public License
>>>> + * Version 2 or later at the following locations:
>>>> + *
>>>> + * http://www.opensource.org/licenses/gpl-license.html
>>>> + * http://www.gnu.org/copyleft/gpl.html
>>>> + */
>>>> +
>>>> +#include <linux/module.h>
>>>> +#include <linux/init.h>
>>>> +#include <linux/irq.h>
>>>> +#include <linux/irqchip.h>
>>>> +#include <linux/irqdomain.h>
>>>> +#include <linux/io.h>
>>>> +#include <linux/ioport.h>
>>>> +#include <linux/of_address.h>
>>>> +#include <linux/of_irq.h>
>>>> +
>>>> +#include <asm/exception.h>
>>>> +#include <asm/hardirq.h>
>>>> +
>>>> +#define	REG_AIC_SCR1	0x00
>>>> +#define	REG_AIC_SCR2	0x04
>>>> +#define	REG_AIC_SCR3	0x08
>>>> +#define	REG_AIC_SCR4	0x0C
>>>> +#define	REG_AIC_SCR5	0x10
>>>> +#define	REG_AIC_SCR6	0x14
>>>> +#define	REG_AIC_SCR7	0x18
>>>> +#define	REG_AIC_SCR8	0x1C
>>>> +#define	REG_AIC_SCR9	0x20
>>>> +#define	REG_AIC_SCR10	0x24
>>>> +#define	REG_AIC_SCR11	0x28
>>>> +#define	REG_AIC_SCR12	0x2C
>>>> +#define	REG_AIC_SCR13	0x30
>>>> +#define	REG_AIC_SCR14	0x34
>>>> +#define	REG_AIC_SCR15	0x38
>>>> +#define	REG_AIC_IRSR	0x100
>>>> +#define	REG_AIC_IRSRH	0x104
>>>> +#define	REG_AIC_IASR	0x108
>>>> +#define	REG_AIC_IASRH	0x10C
>>>> +#define	REG_AIC_ISR	0x110
>>>> +#define	REG_AIC_ISRH	0x114
>>>> +#define	REG_AIC_IPER	0x118
>>>> +#define	REG_AIC_ISNR	0x120
>>>> +#define	REG_AIC_OISR	0x124
>>>> +#define	REG_AIC_IMR	0x128
>>>> +#define	REG_AIC_IMRH	0x12C
>>>> +#define	REG_AIC_MECR	0x130
>>>> +#define	REG_AIC_MECRH	0x134
>>>> +#define	REG_AIC_MDCR	0x138
>>>> +#define	REG_AIC_MDCRH	0x13C
>>>> +#define	REG_AIC_SSCR	0x140
>>>> +#define	REG_AIC_SSCRH	0x144
>>>> +#define	REG_AIC_SCCR	0x148
>>>> +#define	REG_AIC_SCCRH	0x14C
>>>> +#define	REG_AIC_EOSCR	0x150
>>>
>>> Please remove unused defines.
>>
>> Okay.
>>
>>>
>>>> +
>>>> +static void __iomem *aic_base;
>>>> +static struct irq_domain *aic_domain;
>>>> +
>>>> +static void nuc900_irq_mask(struct irq_data *d)
>>>> +{
>>>> +	if (d->irq < 32)
>>>> +		writel(1 << (d->irq), aic_base + REG_AIC_MDCR);
>>>> +	else
>>>> +		writel(1 << (d->irq - 32), aic_base + REG_AIC_MDCRH);
>>>> +}
>>>> +
>>>> +static void nuc900_irq_ack(struct irq_data *d)
>>>> +{
>>>> +	writel(0x01, aic_base + REG_AIC_EOSCR);
>>>> +}
>>>> +
>>>> +static void nuc900_irq_unmask(struct irq_data *d)
>>>> +{
>>>> +	if (d->irq < 32)
>>>> +		writel(1 << (d->irq), aic_base + REG_AIC_MECR);
>>>> +	else
>>>> +		writel(1 << (d->irq - 32), aic_base + REG_AIC_MECRH);
>>>> +}
>>>> +
>>>> +static struct irq_chip nuc900_irq_chip = {
>>>> +	.irq_ack	= nuc900_irq_ack,
>>>> +	.irq_mask	= nuc900_irq_mask,
>>>> +	.irq_unmask	= nuc900_irq_unmask,
>>>> +};
>>>> +
>>>> +void __exception_irq_entry aic_handle_irq(struct pt_regs *regs)
>>>> +{
>>>> +	u32 hwirq;
>>>> +
>>>> +	hwirq = readl(aic_base + REG_AIC_IPER);
>>>> +	hwirq = readl(aic_base + REG_AIC_ISNR);
>>>> +	if (!hwirq)
>>>> +		writel(0x01, aic_base + REG_AIC_EOSCR);
>>>
>>> Could you explain what's going on here?
>>
>> AIC_IPER, When the AIC generates the interrupt, VECTOR represents
>> the interrupt channel number that is active, enabled, and has the
>> highest priority.
>>
>> The value of VECTOR is copied to the register AIC_ISNR thereafter by
>> the AIC. This register was restored a value 0 after it was read by
>> the
>> interrupt handler.
>
> So, iiuc, the first readl() of AIC_IPER kicks the AIC to copy the value
> of VECTOR into AIC_ISNR?  Then we can read it?
>
> If so, please add a comment above the code explaining that.
>
>> So I must read two registers for one irq number, after read IPER,
>> the ISNR(bit0:5) will be updated. ISNR value has no need do offset,
>> it is better than read IPER(bit2:7).
>
> But you aren't using the value from the first readl(...AIC_IPER)?  You
> overwrite hwirq with the value from the second readl(...AIC_ISNR)
> ...
>
> The first part of your explaination makes sense, but this part isn't
> clear to me.

Actually, I have two choice to implement this function:

option1:

void __exception_irq_entry aic_handle_irq(struct pt_regs *regs)
{
	u32 hwirq;

	(void)readl(aic_base + REG_AIC_IPER);
	hwirq = readl(aic_base + REG_AIC_ISNR);

	handle_IRQ((irq_find_mapping(aic_domain, hwirq)), regs);
}

option2:

void __exception_irq_entry aic_handle_irq(struct pt_regs *regs)
{
	u32 hwirq;

	hwirq = readl(aic_base + REG_AIC_IPER);
	hwirq <<= 2;

	handle_IRQ((irq_find_mapping(aic_domain, hwirq)), regs);
}

Though the option2 do shift for hwirq, but it seems better than do io 
operation by readl,so I prefer to option2, agree?

>
>
>> “writel(0x01, aic_base + REG_AIC_EOSCR);”　seems not necessary here,
>> since irqchip has the ack interface. I will remove it.
>
> Ok, thanks.
>
>> This AIC_EOSCR register is used by the interrupt service routine to
>> indicate that it is completely served. Thus, the
>> interrupt handler can write any value to this register to indicate
>> the end of its interrupt service.
>
> A short comment in the ack routine would be helpful.
>
>
>>>> +IRQCHIP_DECLARE(nuc900, "nuvoton,nuc900-aic", aic_of_init);
>>>
>>> afaict, there is no 'nuc900', that's a family.  If so, this compatible
>>> needs to be 'nuvoton,nuc970-aic'.
>>>
>>
>> IRQCHIP_DECLARE(nuvoton, "nuvoton,nuc900-aic", aic_of_init);, change
>> nuc900 to nuvoton, ok?
>
> No, I was only talking about the second argument.  The compatible
> string.  For devicetree, it needs to refer to a specific model number.
> I suspect 'nuc900' is equivalent to saying 'nuc9xx'.  Meaning it refers
> to a family of devices.  The compatible string needs to refer
> specifically to the first model that the binding is compatible with.  In
> this case, I presume that would be 'nuvoton,nuc970-aic'.
>
> thx,
>
> Jason.
>
>