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Re: [PATCH V3 1/2] bcma: gpio: add own IRQ domain

To: Rafał Miłecki <zajec5@gmail.com>
Subject: Re: [PATCH V3 1/2] bcma: gpio: add own IRQ domain
From: Hauke Mehrtens <hauke@hauke-m.de>
Date: Fri, 29 Nov 2013 19:37:11 +0100
Cc: linux-mips@linux-mips.org, Ralf Baechle <ralf@linux-mips.org>
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On 11/29/2013 06:48 PM, Rafał Miłecki wrote:
> Input GPIO changes can generate interrupts, but we need kind of ACK for
> them by changing IRQ polarity. This is required to stop hardware from
> keep generating interrupts and generate another one on the next GPIO
> state change.
> This code allows using GPIOs with standard interrupts and add for
> example GPIO buttons support.
> 
> Signed-off-by: Rafał Miłecki <zajec5@gmail.com>
> ---
> V3: Apply Hauke's comments.
> 1) Use IRQ domain for CONFIG_BCMA_HOST_SOC only
> 2) Optimize bcma_gpio_irq_handler
> 3) Register GPIO chip after doing everything else
> 4) Improve cleaning paths
> ---
>  drivers/bcma/Kconfig                        |    1 +
>  drivers/bcma/driver_gpio.c                  |  126 
> ++++++++++++++++++++++++++-
>  include/linux/bcma/bcma_driver_chipcommon.h |    1 +
>  3 files changed, 126 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/bcma/Kconfig b/drivers/bcma/Kconfig
> index 7c081b3..0ee48be 100644
> --- a/drivers/bcma/Kconfig
> +++ b/drivers/bcma/Kconfig
> @@ -75,6 +75,7 @@ config BCMA_DRIVER_GMAC_CMN
>  config BCMA_DRIVER_GPIO
>       bool "BCMA GPIO driver"
>       depends on BCMA && GPIOLIB
> +     select IRQ_DOMAIN if BCMA_HOST_SOC
>       help
>         Driver to provide access to the GPIO pins of the bcma bus.
>  
> diff --git a/drivers/bcma/driver_gpio.c b/drivers/bcma/driver_gpio.c
> index 45f0996..fe9b1bc 100644
> --- a/drivers/bcma/driver_gpio.c
> +++ b/drivers/bcma/driver_gpio.c
> @@ -9,6 +9,9 @@
>   */
>  
>  #include <linux/gpio.h>
> +#include <linux/irq.h>
> +#include <linux/interrupt.h>
> +#include <linux/irqdomain.h>
>  #include <linux/export.h>
>  #include <linux/bcma/bcma.h>
>  
> @@ -73,19 +76,117 @@ static void bcma_gpio_free(struct gpio_chip *chip, 
> unsigned gpio)
>       bcma_chipco_gpio_pullup(cc, 1 << gpio, 0);
>  }
>  
> +#ifdef CONFIG_BCMA_HOST_SOC
>  static int bcma_gpio_to_irq(struct gpio_chip *chip, unsigned gpio)
>  {
>       struct bcma_drv_cc *cc = bcma_gpio_get_cc(chip);
>  
>       if (cc->core->bus->hosttype == BCMA_HOSTTYPE_SOC)
> -             return bcma_core_irq(cc->core);
> +             return irq_find_mapping(cc->irq_domain, gpio);
>       else
>               return -EINVAL;
>  }
>  
> +static void bcma_gpio_irq_unmask(struct irq_data *d)
> +{
> +     struct bcma_drv_cc *cc = irq_data_get_irq_chip_data(d);
> +     int gpio = irqd_to_hwirq(d);
> +
> +     bcma_chipco_gpio_intmask(cc, BIT(gpio), BIT(gpio));
> +}
> +
> +static void bcma_gpio_irq_mask(struct irq_data *d)
> +{
> +     struct bcma_drv_cc *cc = irq_data_get_irq_chip_data(d);
> +     int gpio = irqd_to_hwirq(d);
> +
> +     bcma_chipco_gpio_intmask(cc, BIT(gpio), 0);
> +}
> +
> +static struct irq_chip bcma_gpio_irq_chip = {
> +     .name           = "BCMA-GPIO",
> +     .irq_mask       = bcma_gpio_irq_mask,
> +     .irq_unmask     = bcma_gpio_irq_unmask,
> +};
> +
> +static irqreturn_t bcma_gpio_irq_handler(int irq, void *dev_id)
> +{
> +     struct bcma_drv_cc *cc = dev_id;
> +     u32 val = bcma_cc_read32(cc, BCMA_CC_GPIOIN);
> +     u32 mask = bcma_cc_read32(cc, BCMA_CC_GPIOIRQ);
> +     u32 pol = bcma_cc_read32(cc, BCMA_CC_GPIOPOL);
> +     u32 irqs = (val ^ pol) & mask;
> +     u32 pol_mask = 0, pol_val = 0;
> +     int gpio;
> +
> +     for_each_set_bit(gpio, (unsigned long *)&irqs, cc->gpio.ngpio) {
> +             generic_handle_irq(bcma_gpio_to_irq(&cc->gpio, gpio));
> +             pol_mask |= BIT(gpio);
> +             if (val & BIT(gpio))
> +                     pol_val |= BIT(gpio);
> +     }

Instead of calculation pol_mask and pol_val bit for bit manually, you
can pretty easy calculate valid value like this:
pol_mask = irqs;
pol_val = val & irqs;

> +     bcma_chipco_gpio_polarity(cc, pol_mask, pol_val);
> +
> +     return irqs ? IRQ_HANDLED : IRQ_NONE;
> +}
> +
> +static int bcma_gpio_irq_domain_init(struct bcma_drv_cc *cc)
> +{
> +     struct gpio_chip *chip = &cc->gpio;
> +     int gpio, hwirq, err;
> +
> +     cc->irq_domain = irq_domain_add_linear(NULL, chip->ngpio,
> +                                            &irq_domain_simple_ops, cc);
> +     if (!cc->irq_domain) {
> +             err = -ENODEV;
> +             goto err_irq_domain;
> +     }
> +     for (gpio = 0; gpio < chip->ngpio; gpio++) {
> +             int irq = irq_create_mapping(cc->irq_domain, gpio);
> +
> +             irq_set_chip_data(irq, cc);
> +             irq_set_chip_and_handler(irq, &bcma_gpio_irq_chip,
> +                                      handle_simple_irq);
> +     }
> +
> +     hwirq = bcma_core_irq(cc->core);
> +     err = request_irq(hwirq, bcma_gpio_irq_handler, IRQF_SHARED, "gpio",
> +                       cc);
> +     if (err)
> +             goto err_req_irq;
> +
> +     return 0;
> +
> +err_req_irq:
> +     for (gpio = 0; gpio < chip->ngpio; gpio++) {
> +             int irq = irq_find_mapping(cc->irq_domain, gpio);
> +
> +             irq_dispose_mapping(irq);
> +     }
> +     irq_domain_remove(cc->irq_domain);
> +err_irq_domain:
> +     return err;
> +}
> +
> +static void bcma_gpio_irq_domain_exit(struct bcma_drv_cc *cc)
> +{
> +     struct gpio_chip *chip = &cc->gpio;
> +     int gpio;
> +
> +     free_irq(bcma_core_irq(cc->core), cc);
> +     for (gpio = 0; gpio < chip->ngpio; gpio++) {
> +             int irq = irq_find_mapping(cc->irq_domain, gpio);
> +
> +             irq_dispose_mapping(irq);
> +     }
> +     irq_domain_remove(cc->irq_domain);
> +}
> +#endif

I do not like all these ifdefs, why not add this and remove some of them
from the code in bcma_gpio_init():

#else /* CONFIG_BCMA_HOST_SOC */

static int bcma_gpio_irq_domain_init(struct bcma_drv_cc *cc)
{
        return 0;
}
static void bcma_gpio_irq_domain_exit(struct bcma_drv_cc *cc)
{
        /* Nothing */
}
#endif /* CONFIG_BCMA_HOST_SOC */

> +
>  int bcma_gpio_init(struct bcma_drv_cc *cc)
>  {
>       struct gpio_chip *chip = &cc->gpio;
> +     int err;
>  
>       chip->label             = "bcma_gpio";
>       chip->owner             = THIS_MODULE;
> @@ -95,7 +196,9 @@ int bcma_gpio_init(struct bcma_drv_cc *cc)
>       chip->set               = bcma_gpio_set_value;
>       chip->direction_input   = bcma_gpio_direction_input;
>       chip->direction_output  = bcma_gpio_direction_output;
> +#ifdef CONFIG_BCMA_HOST_SOC
>       chip->to_irq            = bcma_gpio_to_irq;
> +#endif
>       chip->ngpio             = 16;
>       /* There is just one SoC in one device and its GPIO addresses should be
>        * deterministic to address them more easily. The other buses could get
> @@ -105,10 +208,29 @@ int bcma_gpio_init(struct bcma_drv_cc *cc)
>       else
>               chip->base              = -1;
>  
> -     return gpiochip_add(chip);
> +#ifdef CONFIG_BCMA_HOST_SOC
> +     err = bcma_gpio_irq_domain_init(cc);
> +     if (err)
> +             return err;
> +#endif
> +
> +     err = gpiochip_add(chip);
> +     if (err) {
> +#ifdef CONFIG_BCMA_HOST_SOC
> +             bcma_gpio_irq_domain_exit(cc);
> +#endif
> +             return err;
> +     }
> +
> +     bcma_cc_set32(cc, BCMA_CC_IRQMASK, BCMA_CC_IRQ_GPIO);

This should be moved into bcma_gpio_irq_domain_ini(), I do not know what
happens when we activate them on a PCIe device. IRQs should get
deactivated in bcma_gpio_irq_domain_exit().

> +
> +     return 0;
>  }
>  
>  int bcma_gpio_unregister(struct bcma_drv_cc *cc)
>  {
> +#ifdef CONFIG_BCMA_HOST_SOC
> +     bcma_gpio_irq_domain_exit(cc);
> +#endif
>       return gpiochip_remove(&cc->gpio);
>  }
> diff --git a/include/linux/bcma/bcma_driver_chipcommon.h 
> b/include/linux/bcma/bcma_driver_chipcommon.h
> index c49e1a1..63d105c 100644
> --- a/include/linux/bcma/bcma_driver_chipcommon.h
> +++ b/include/linux/bcma/bcma_driver_chipcommon.h
> @@ -640,6 +640,7 @@ struct bcma_drv_cc {
>       spinlock_t gpio_lock;
>  #ifdef CONFIG_BCMA_DRIVER_GPIO
>       struct gpio_chip gpio;
> +     struct irq_domain *irq_domain;
>  #endif
>  };
>  
> 


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