Date:	Tue, 21 Feb 2012 08:07:23 -0600
From:	Rob Herring <robherring2@...il.com>
To:	Nicolas Ferre <nicolas.ferre@...el.com>
CC:	plagnioj@...osoft.com, linux-arm-kernel@...ts.infradead.org,
	grant.likely@...retlab.ca, rob.herring@...xeda.com,
	devicetree-discuss@...ts.ozlabs.org, tglx@...utronix.de,
	avictor.za@...il.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ARM: at91: AIC and GPIO IRQ device tree initilization

On 02/17/2012 03:27 AM, Nicolas Ferre wrote:
> Both AIC and GPIO controllers are now using the standard of_irq_init()
> function to initialize IRQs in case of DT use.
> The DT specific initialization functions are now separated from the
> non-DT case and are now using "linear" irq domains.
> The .map() irqdomain operation is responsible for positioning the IRQ
> handlers. In AIC case, the Linux IRQ number is directly programmed in
> the hardware to avoid an additional reverse mapping operation.
> The AIC position its irq domain as the "default" irq domain.
> 
> For DT case, the priority is not yet filled in the SMR. It will be the
> subject of another patch.
> 
> Signed-off-by: Nicolas Ferre <nicolas.ferre@...el.com>
> ---
> Hi,
> 
> This patch goes on top of previous series:
> "[PATCH 0/9] ARM: at91: irqdomain and device tree for AIC and GPIO"
> (which goes on top of Grant's "irq_domain generalization and rework").
> 
> It should address all advices by Rob Herring and I hope it is the best
> way to deal with irq domains in all DT/non-DT cases.
> 
> A simple concern is that the IRQ latency may be bigger because of the
> irq_create_mapping() call in .to_irq(). This is called in the hot path
> of GPIO IRQ handler...


Why are you not using irq_find_mapping?

> Best regards,
> 
> 
>  arch/arm/mach-at91/board-dt.c |   11 +++-
>  arch/arm/mach-at91/generic.h  |    6 ++
>  arch/arm/mach-at91/gpio.c     |  124 +++++++++++++++++++++++++++++++----------
>  arch/arm/mach-at91/irq.c      |   92 ++++++++++++++++++++-----------
>  4 files changed, 171 insertions(+), 62 deletions(-)
> 
> diff --git a/arch/arm/mach-at91/board-dt.c b/arch/arm/mach-at91/board-dt.c
> index 6120978..e0df4e5 100644
> --- a/arch/arm/mach-at91/board-dt.c
> +++ b/arch/arm/mach-at91/board-dt.c
> @@ -15,6 +15,8 @@
>  #include <linux/init.h>
>  #include <linux/module.h>
>  #include <linux/gpio.h>
> +#include <linux/of.h>
> +#include <linux/of_irq.h>
>  #include <linux/of_platform.h>
>  
>  #include <mach/hardware.h>
> @@ -86,9 +88,16 @@ static void __init ek_add_device_nand(void)
>  	at91_add_device_nand(&ek_nand_data);
>  }
>  
> +static const struct of_device_id irq_of_match[] __initconst = {
> +
> +	{ .compatible = "atmel,at91rm9200-aic", .data = at91_aic_of_init },
> +	{ .compatible = "atmel,at91rm9200-gpio", .data = at91_gpio_of_irq_setup },
> +	{ /*sentinel*/ }
> +};
> +
>  static void __init at91_dt_init_irq(void)
>  {
> -	at91_init_irq_default();
> +	of_irq_init(irq_of_match);
>  }
>  
>  static void __init at91_dt_device_init(void)
> diff --git a/arch/arm/mach-at91/generic.h b/arch/arm/mach-at91/generic.h
> index 78cd605..c5d16e5 100644
> --- a/arch/arm/mach-at91/generic.h
> +++ b/arch/arm/mach-at91/generic.h
> @@ -9,6 +9,7 @@
>   */
>  
>  #include <linux/clkdev.h>
> +#include <linux/of.h>
>  
>   /* Map io */
>  extern void __init at91_map_io(void);
> @@ -25,6 +26,9 @@ extern void __init at91_init_irq_default(void);
>  extern void __init at91_init_interrupts(unsigned int priority[]);
>  extern void __init at91x40_init_interrupts(unsigned int priority[]);
>  extern void __init at91_aic_init(unsigned int priority[]);
> +extern int  __init at91_aic_of_init(struct device_node *node,
> +				    struct device_node *parent);
> +
>  
>   /* Timer */
>  struct sys_timer;
> @@ -75,5 +79,7 @@ struct at91_gpio_bank {
>  };
>  extern void __init at91_gpio_init(struct at91_gpio_bank *, int nr_banks);
>  extern void __init at91_gpio_irq_setup(void);
> +extern int  __init at91_gpio_of_irq_setup(struct device_node *node,
> +					  struct device_node *parent);
>  
>  extern int at91_extern_irq;
> diff --git a/arch/arm/mach-at91/gpio.c b/arch/arm/mach-at91/gpio.c
> index fbcb47e..64395a5 100644
> --- a/arch/arm/mach-at91/gpio.c
> +++ b/arch/arm/mach-at91/gpio.c
> @@ -27,6 +27,7 @@
>  #include <linux/irqdomain.h>
>  #include <linux/of_address.h>
>  #include <linux/of_irq.h>
> +#include <linux/of_gpio.h>
>  
>  #include <mach/hardware.h>
>  #include <mach/at91_pio.h>
> @@ -37,6 +38,7 @@ struct at91_gpio_chip {
>  	struct gpio_chip	chip;
>  	struct at91_gpio_chip	*next;		/* Bank sharing same clock */
>  	int			pioc_hwirq;	/* PIO bank interrupt identifier on AIC */
> +	int			pioc_virq;	/* PIO bank Linux virtual interrupt */
>  	int			pioc_idx;	/* PIO bank index */
>  	void __iomem		*regbase;	/* PIO bank virtual address */
>  	struct clk		*clock;		/* associated clock */
> @@ -295,7 +297,7 @@ static int gpio_irq_set_wake(struct irq_data *d, unsigned state)
>  	else
>  		wakeups[bank] &= ~mask;
>  
> -	irq_set_irq_wake(gpio_chip[bank].pioc_hwirq, state);
> +	irq_set_irq_wake(at91_gpio->pioc_virq, state);
>  
>  	return 0;
>  }
> @@ -397,12 +399,12 @@ static struct irq_chip gpio_irqchip = {
>  
>  static void gpio_irq_handler(unsigned irq, struct irq_desc *desc)
>  {
> -	unsigned	virq;
>  	struct irq_data *idata = irq_desc_get_irq_data(desc);
>  	struct irq_chip *chip = irq_data_get_irq_chip(idata);
>  	struct at91_gpio_chip *at91_gpio = irq_data_get_irq_chip_data(idata);
>  	void __iomem	*pio = at91_gpio->regbase;
> -	u32		isr;
> +	unsigned long	isr;
> +	int		n;
>  
>  	/* temporarily mask (level sensitive) parent IRQ */
>  	chip->irq_ack(idata);
> @@ -420,13 +422,10 @@ static void gpio_irq_handler(unsigned irq, struct irq_desc *desc)
>  			continue;
>  		}
>  
> -		virq = gpio_to_irq(at91_gpio->chip.base);
> -
> -		while (isr) {
> -			if (isr & 1)
> -				generic_handle_irq(virq);
> -			virq++;
> -			isr >>= 1;
> +		n = find_first_bit(&isr, BITS_PER_LONG);
> +		while (n < BITS_PER_LONG) {
> +			generic_handle_irq(at91_gpiolib_to_irq(&at91_gpio->chip, n));
> +			n = find_next_bit(&isr, BITS_PER_LONG, n + 1);
>  		}
>  	}
>  	chip->irq_unmask(idata);
> @@ -496,23 +495,91 @@ postcore_initcall(at91_gpio_debugfs_init);
>  /*--------------------------------------------------------------------------*/
>  
>  /*
> + * This lock class tells lockdep that GPIO irqs are in a different
> + * category than their parents, so it won't report false recursion.
> + */
> +static struct lock_class_key gpio_lock_class;
> +
> +#if defined(CONFIG_OF)
> +static int at91_gpio_irq_map(struct irq_domain *h, unsigned int virq,
> +							irq_hw_number_t hw)
> +{
> +	struct at91_gpio_chip	*at91_gpio = h->host_data;
> +
> +	irq_set_lockdep_class(virq, &gpio_lock_class);
> +
> +	/*
> +	 * Can use the "simple" and not "edge" handler since it's
> +	 * shorter, and the AIC handles interrupts sanely.
> +	 */
> +	irq_set_chip_and_handler(virq, &gpio_irqchip,
> +				 handle_simple_irq);
> +	set_irq_flags(virq, IRQF_VALID);
> +	irq_set_chip_data(virq, at91_gpio);
> +
> +	return 0;
> +}
> +
> +static struct irq_domain_ops at91_gpio_ops = {
> +	.map	= at91_gpio_irq_map,
> +	.xlate	= irq_domain_xlate_twocell,
> +};
> +
> +int __init at91_gpio_of_irq_setup(struct device_node *node,
> +				     struct device_node *parent)
> +{
> +	struct at91_gpio_chip	*prev = NULL;
> +	int			alias_idx = of_alias_get_id(node, "gpio");
> +	struct at91_gpio_chip	*at91_gpio = &gpio_chip[alias_idx];
> +
> +	/* Disable irqs of this PIO controller */
> +	__raw_writel(~0, at91_gpio->regbase + PIO_IDR);
> +
> +	/* Setup irq domain */
> +	at91_gpio->domain = irq_domain_add_linear(node, at91_gpio->chip.ngpio,
> +						&at91_gpio_ops, at91_gpio);
> +	if (!at91_gpio->domain)
> +		panic("at91_gpio.%d: couldn't allocate irq domain (DT).\n",
> +			at91_gpio->pioc_idx);
> +
> +	/* Setup chained handler */
> +	if (at91_gpio->pioc_idx)
> +		prev = &gpio_chip[at91_gpio->pioc_idx - 1];
> +
> +	/* The toplevel handler handles one bank of GPIOs, except
> +	 * on some SoC it can handles up to three...
> +	 * We only set up the handler for the first of the list.
> +	 */
> +	if (prev && prev->next == at91_gpio)
> +		return 0;
> +
> +	at91_gpio->pioc_virq = irq_create_mapping(irq_find_host(parent),
> +							at91_gpio->pioc_hwirq);
> +	irq_set_chip_data(at91_gpio->pioc_virq, at91_gpio);
> +	irq_set_chained_handler(at91_gpio->pioc_virq, gpio_irq_handler);
> +
> +	return 0;
> +}
> +#else
> +int __init at91_gpio_of_irq_setup(struct device_node *node,
> +				     struct device_node *parent)
> +{
> +	return -EINVAL;
> +}
> +#endif
> +
> +/*
>   * irqdomain initialization: pile up irqdomains on top of AIC range
>   */
>  static void __init at91_gpio_irqdomain(struct at91_gpio_chip *at91_gpio)
>  {
>  	int irq_base;
> -#if defined(CONFIG_OF)
> -	struct device_node *of_node = at91_gpio->chip.of_node;
> -#else
> -	struct device_node *of_node = NULL;
> -#endif
>  
>  	irq_base = irq_alloc_descs(-1, 0, at91_gpio->chip.ngpio, 0);
>  	if (irq_base < 0)
>  		panic("at91_gpio.%d: error %d: couldn't allocate IRQ numbers.\n",
>  			at91_gpio->pioc_idx, irq_base);
> -	at91_gpio->domain = irq_domain_add_legacy(of_node,
> -						  at91_gpio->chip.ngpio,
> +	at91_gpio->domain = irq_domain_add_legacy(NULL, at91_gpio->chip.ngpio,
>  						  irq_base, 0,
>  						  &irq_domain_simple_ops, NULL);
>  	if (!at91_gpio->domain)
> @@ -521,12 +588,6 @@ static void __init at91_gpio_irqdomain(struct at91_gpio_chip *at91_gpio)
>  }
>  
>  /*
> - * This lock class tells lockdep that GPIO irqs are in a different
> - * category than their parents, so it won't report false recursion.
> - */
> -static struct lock_class_key gpio_lock_class;
> -
> -/*
>   * Called from the processor-specific init to enable GPIO interrupt support.
>   */
>  void __init at91_gpio_irq_setup(void)
> @@ -538,8 +599,7 @@ void __init at91_gpio_irq_setup(void)
>  	for (pioc = 0, this = gpio_chip, prev = NULL;
>  			pioc++ < gpio_banks;
>  			prev = this, this++) {
> -		unsigned	pioc_hwirq = this->pioc_hwirq;
> -		int		offset;
> +		int offset;
>  
>  		__raw_writel(~0, this->regbase + PIO_IDR);
>  
> @@ -547,7 +607,7 @@ void __init at91_gpio_irq_setup(void)
>  		at91_gpio_irqdomain(this);
>  
>  		for (offset = 0; offset < this->chip.ngpio; offset++) {
> -			unsigned int virq = irq_find_mapping(this->domain, offset);
> +			unsigned int virq = irq_create_mapping(this->domain, offset);

This should get done by irq_domain_add_legacy.


>  			irq_set_lockdep_class(virq, &gpio_lock_class);
>  
>  			/*
> @@ -569,8 +629,9 @@ void __init at91_gpio_irq_setup(void)
>  		if (prev && prev->next == this)
>  			continue;
>  
> -		irq_set_chip_data(pioc_hwirq, this);
> -		irq_set_chained_handler(pioc_hwirq, gpio_irq_handler);
> +		this->pioc_virq = irq_create_mapping(NULL, this->pioc_hwirq);
> +		irq_set_chip_data(this->pioc_virq, this);
> +		irq_set_chained_handler(this->pioc_virq, gpio_irq_handler);
>  	}
>  	pr_info("AT91: %d gpio irqs in %d banks\n", gpio_irqnbr, gpio_banks);
>  }
> @@ -648,7 +709,12 @@ static void at91_gpiolib_dbg_show(struct seq_file *s, struct gpio_chip *chip)
>  static int at91_gpiolib_to_irq(struct gpio_chip *chip, unsigned offset)
>  {
>  	struct at91_gpio_chip *at91_gpio = to_at91_gpio_chip(chip);
> -	int virq = irq_find_mapping(at91_gpio->domain, offset);
> +	int virq;
> +
> +	if (offset < chip->ngpio)
> +		virq = irq_create_mapping(at91_gpio->domain, offset);
> +	else
> +		virq = -ENXIO;
>  
>  	dev_dbg(chip->dev, "%s: request IRQ for GPIO %d, return %d\n",
>  				chip->label, offset + chip->base, virq);
> diff --git a/arch/arm/mach-at91/irq.c b/arch/arm/mach-at91/irq.c
> index 46682fa..2e4ee09 100644
> --- a/arch/arm/mach-at91/irq.c
> +++ b/arch/arm/mach-at91/irq.c
> @@ -135,27 +135,72 @@ static struct irq_chip at91_aic_chip = {
>  	.irq_set_wake	= at91_aic_set_wake,
>  };
>  
> +static void __init at91_aic_hw_init(unsigned int spu_vector)
> +{
> +	int i;
> +
> +	/*
> +	 * Perform 8 End Of Interrupt Command to make sure AIC
> +	 * will not Lock out nIRQ
> +	 */
> +	for (i = 0; i < 8; i++)
> +		at91_aic_write(AT91_AIC_EOICR, 0);
> +
> +	/*
> +	 * Spurious Interrupt ID in Spurious Vector Register.
> +	 * When there is no current interrupt, the IRQ Vector Register
> +	 * reads the value stored in AIC_SPU
> +	 */
> +	at91_aic_write(AT91_AIC_SPU, spu_vector);
> +
> +	/* No debugging in AIC: Debug (Protect) Control Register */
> +	at91_aic_write(AT91_AIC_DCR, 0);
> +
> +	/* Disable and clear all interrupts initially */
> +	at91_aic_write(AT91_AIC_IDCR, 0xFFFFFFFF);
> +	at91_aic_write(AT91_AIC_ICCR, 0xFFFFFFFF);
> +}
> +
> +
> +

Remove extra blank lines.

>  #if defined(CONFIG_OF)
> -static int __init __at91_aic_of_init(struct device_node *node,
> -				     struct device_node *parent)
> +static int at91_aic_irq_map(struct irq_domain *h, unsigned int virq,
> +							irq_hw_number_t hw)
>  {
> -	at91_aic_base = of_iomap(node, 0);
> -	at91_aic_np = node;
> +	/* Put virq number in Source Vector Register */
> +	at91_aic_write(AT91_AIC_SVR(hw), virq);
> +
> +	/* Active Low interrupt, without priority */
> +	at91_aic_write(AT91_AIC_SMR(hw), AT91_AIC_SRCTYPE_LOW);
> +
> +	irq_set_chip_and_handler(virq, &at91_aic_chip, handle_level_irq);
> +	set_irq_flags(virq, IRQF_VALID | IRQF_PROBE);
>  
>  	return 0;
>  }
>  
> -static const struct of_device_id aic_ids[] __initconst = {
> -	{ .compatible = "atmel,at91rm9200-aic", .data = __at91_aic_of_init },
> -	{ /*sentinel*/ }
> +static struct irq_domain_ops at91_aic_irq_ops = {
> +	.map	= at91_aic_irq_map,
> +	.xlate	= irq_domain_xlate_twocell,
>  };
>  
> -static void __init at91_aic_of_init(void)
> +int __init at91_aic_of_init(struct device_node *node,
> +				     struct device_node *parent)
>  {
> -	of_irq_init(aic_ids);
> +	at91_aic_base = of_iomap(node, 0);
> +	at91_aic_np = node;
> +
> +	at91_aic_domain = irq_domain_add_linear(at91_aic_np, NR_AIC_IRQS,
> +						&at91_aic_irq_ops, NULL);
> +	if (!at91_aic_domain)
> +		panic("Unable to add AIC irq domain (DT)\n");
> +
> +	irq_set_default_host(at91_aic_domain);

Is this really necessary? I don't think it should be.

> +
> +	at91_aic_hw_init(NR_AIC_IRQS);
> +
> +	return 0;
>  }
> -#else
> -static void __init at91_aic_of_init(void) {}
>  #endif
>  
>  /*
> @@ -166,11 +211,7 @@ void __init at91_aic_init(unsigned int priority[NR_AIC_IRQS])
>  	unsigned int i;
>  	int irq_base;
>  
> -	if (of_have_populated_dt())
> -		at91_aic_of_init();
> -	else
> -		at91_aic_base = ioremap(AT91_AIC, 512);
> -
> +	at91_aic_base = ioremap(AT91_AIC, 512);
>  	if (!at91_aic_base)
>  		panic("Unable to ioremap AIC registers\n");
>  
> @@ -187,6 +228,8 @@ void __init at91_aic_init(unsigned int priority[NR_AIC_IRQS])
>  	if (!at91_aic_domain)
>  		panic("Unable to add AIC irq domain\n");
>  
> +	irq_set_default_host(at91_aic_domain);
> +
>  	/*
>  	 * The IVR is used by macro get_irqnr_and_base to read and verify.
>  	 * The irq number is NR_AIC_IRQS when a spurious interrupt has occurred.
> @@ -199,22 +242,7 @@ void __init at91_aic_init(unsigned int priority[NR_AIC_IRQS])
>  
>  		irq_set_chip_and_handler(i, &at91_aic_chip, handle_level_irq);
>  		set_irq_flags(i, IRQF_VALID | IRQF_PROBE);
> -
> -		/* Perform 8 End Of Interrupt Command to make sure AIC will not Lock out nIRQ */
> -		if (i < 8)
> -			at91_aic_write(AT91_AIC_EOICR, 0);
>  	}
>  
> -	/*
> -	 * Spurious Interrupt ID in Spurious Vector Register is NR_AIC_IRQS
> -	 * When there is no current interrupt, the IRQ Vector Register reads the value stored in AIC_SPU
> -	 */
> -	at91_aic_write(AT91_AIC_SPU, NR_AIC_IRQS);
> -
> -	/* No debugging in AIC: Debug (Protect) Control Register */
> -	at91_aic_write(AT91_AIC_DCR, 0);
> -
> -	/* Disable and clear all interrupts initially */
> -	at91_aic_write(AT91_AIC_IDCR, 0xFFFFFFFF);
> -	at91_aic_write(AT91_AIC_ICCR, 0xFFFFFFFF);
> +	at91_aic_hw_init(NR_AIC_IRQS);
>  }

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