[PATCH v3 1/3] ARM: bcm281xx: Add GPIO driver

[Sudeep.KarkadaNagesha@arm.com (Sudeep KarkadaNagesha)]

On 26/07/13 21:25, Markus Mayer wrote:
> From: Markus Mayer <mmayer@broadcom.com>
> 
> This patch adds the GPIO driver for the bcm281xx family of chips.
> 
May be I am missing my mails, but I could not find even in archives.
The patch says its v3, I could not trace v1/v2 and not change log.

> Signed-off-by: Markus Mayer <markus.mayer@linaro.org>
> Reviewed-by: Ray Jui <rjui@broadcom.com>
> Reviewed-by: Christian Daudt <csd@broadcom.com>
> Reviewed-by: Tim Kryger <tim.kryger@linaro.org>
> Reviewed-by: Matt Porter <matt.porter@linaro.org>
> Reviewed-by: Alex Elder <alex.elder@linaro.org>
> ---
>  drivers/gpio/gpio-bcm-kona.c |  697 ++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 697 insertions(+)
>  create mode 100644 drivers/gpio/gpio-bcm-kona.c
> 
> diff --git a/drivers/gpio/gpio-bcm-kona.c b/drivers/gpio/gpio-bcm-kona.c
> new file mode 100644
> index 0000000..ca6cb7e
> --- /dev/null
> +++ b/drivers/gpio/gpio-bcm-kona.c
> @@ -0,0 +1,697 @@
> +/*
> + * Copyright (C) 2012-2013 Broadcom Corporation
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License as
> + * published by the Free Software Foundation version 2.
> + *
> + * This program is distributed "as is" WITHOUT ANY WARRANTY of any
> + * kind, whether express or implied; without even the implied warranty
> + * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + */
> +
> +#include <linux/io.h>
> +#include <linux/gpio.h>
> +#include <linux/of_device.h>
> +#include <linux/module.h>
> +#include <linux/irqdomain.h>
> +#include <linux/irqchip/chained_irq.h>
> +
> +#define BCM_GPIO_PASSWD        0x00a5a501
> +#define GPIO_PER_BANK  32
> +
> +#define GPIO_BANK(gpio)        ((gpio) >> 5)
> +#define GPIO_BIT(gpio) ((gpio) & (GPIO_PER_BANK - 1))
> +
> +#define GPIO_GPOR0_OFFSET                                      0x00000000
> +#define GPIO_GPIR0_OFFSET                                      0x00000020
> +#define GPIO_GPORS0_OFFSET                                     0x00000040
> +#define GPIO_GPORC0_OFFSET                                     0x00000060
> +#define GPIO_ISR0_OFFSET                                       0x00000080
> +#define GPIO_IMR0_OFFSET                                       0x000000A0
> +#define GPIO_IMRC0_OFFSET                                      0x000000C0
> +#define GPIO_GPCTR0_OFFSET                                     0x00000100
> +#define GPIO_GPPLSR0_OFFSET                                    0x00000500
> +#define GPIO_GPPWR_OFFSET                                      0x00000520
> +
Why these macros can't be something like this ?
#define GPIO_GPOR_OFFSET(bank)	(0x00000000 + (bank) << 2)

> +#define GPIO_GPCTR0_DBR_SHIFT                                  5
> +#define GPIO_GPCTR0_DBR_MASK                                   0x000001E0
> +
> +#define GPIO_GPCTR0_ITR_SHIFT                                  3
> +#define GPIO_GPCTR0_ITR_MASK                                   0x00000018
> +#define GPIO_GPCTR0_ITR_CMD_RISING_EDGE                                0x00000001
> +#define GPIO_GPCTR0_ITR_CMD_FALLING_EDGE                       0x00000002
> +#define GPIO_GPCTR0_ITR_CMD_BOTH_EDGE                          0x00000003
> +
> +#define GPIO_GPCTR0_IOTR_MASK                                  0x00000001
> +#define GPIO_GPCTR0_IOTR_CMD_0UTPUT                            0x00000000
> +#define GPIO_GPCTR0_IOTR_CMD_INPUT                             0x00000001
> +
> +#define GPIO_GPCTR0_DB_ENABLE_MASK                             0x00000100
> +
> +#define LOCK_CODE      0xFFFFFFFF
> +#define UNLOCK_CODE    0x0
> +
> +struct bcm_kona_gpio_bank {
> +       int id;
> +       int irq;
> +};
> +
> +struct bcm_kona_gpio {
> +       struct irq_domain *irq_domain;
> +       void __iomem *reg_base;
> +       int num_bank;
> +       int irq_base;
> +       spinlock_t lock;
> +       struct bcm_kona_gpio_bank *banks;
> +};
> +
> +static struct gpio_chip bcm_gpio_chip;
> +
Can this be embed in bcm_kona_gpio?
You can then get rid of all the accesses to global variable
bcm_kona_gpio.

> +static void bcm_kona_gpio_irq_mask(struct irq_data *d);
> +static void bcm_kona_gpio_irq_unmask(struct irq_data *d);
> +
> +static struct bcm_kona_gpio bcm_kona_gpio;
> +
Can this be allocated dynamically ?
And the changed global pointer can be accessed only in probe.
You can remove all direct access once you embed as mentioned above.

> +static inline u32 bcm_kona_gpio_out_status(int bank)
> +{
> +       return GPIO_GPOR0_OFFSET + (bank << 2);
> +}
> +
> +static inline u32 bcm_kona_gpio_in_status(int bank)
> +{
> +       return GPIO_GPIR0_OFFSET + (bank << 2);
> +}
> +
> +static inline u32 bcm_kona_gpio_out_set(int bank)
> +{
> +       return GPIO_GPORS0_OFFSET + (bank << 2);
> +}
> +
> +static inline u32 bcm_kona_gpio_out_clear(int bank)
> +{
> +       return GPIO_GPORC0_OFFSET + (bank << 2);
> +}
> +
> +static inline u32 bcm_kona_gpio_int_status(int bank)
> +{
> +       return GPIO_ISR0_OFFSET + (bank << 2);
> +}
> +
> +static inline u32 bcm_kona_gpio_int_mask(int bank)
> +{
> +       return GPIO_IMR0_OFFSET + (bank << 2);
> +}
> +
> +static inline u32 bcm_kona_gpio_int_mskclr(int bank)
> +{
> +       return GPIO_IMRC0_OFFSET + (bank << 2);
> +}
> +
> +static inline u32 bcm_kona_gpio_pwd_status(int bank)
> +{
> +       return GPIO_GPPLSR0_OFFSET + (bank << 2);
> +}
> +
> +static inline u32 bcm_kona_gpio_control(int gpio)
> +{
> +       return GPIO_GPCTR0_OFFSET + (gpio << 2);
> +}
All these functions can go away if you can have the macros as shown above ?

> +
> +static int bcm_kona_count_irq_resources(struct platform_device *pdev)
> +{
> +       struct resource *res;
> +       int count = 0;
> +
> +       for (;;) {
> +               res = platform_get_resource(pdev, IORESOURCE_IRQ, count);
platform_get_irq instead

> +               if (!res)
> +                       break;
> +               count++;
> +       }
> +       return count;
> +}
> +
> +static void  bcm_kona_gpio_set_lockcode_bank(int bank_id, int lockcode)
> +{
> +       void __iomem *reg_base = bcm_kona_gpio.reg_base;
pass gpio_chip to avoid using global

> +       /* This register is password protected  */
> +       writel(BCM_GPIO_PASSWD, reg_base + GPIO_GPPWR_OFFSET);
> +       /* Lock the bank */
> +       writel(lockcode, reg_base + bcm_kona_gpio_pwd_status(bank_id));
> +}
> +
> +static inline void bcm_kona_gpio_lock_bank(int bank_id)
ditto

> +{
> +       bcm_kona_gpio_set_lockcode_bank(bank_id, LOCK_CODE);
> +}
> +
> +static inline void bcm_kona_gpio_unlock_bank(int bank_id)
ditto

> +{
> +       bcm_kona_gpio_set_lockcode_bank(bank_id, UNLOCK_CODE);
> +}
> +
> +static void bcm_kona_gpio_set(struct gpio_chip *chip, unsigned gpio,
> +       int value)
> +{
> +       int bank_id = GPIO_BANK(gpio);
> +       int bit = GPIO_BIT(gpio);
> +       void __iomem *reg_base = bcm_kona_gpio.reg_base;
fetch bcm_kona_gpio from gpio_chip

> +       u32 val, reg_offset;
> +       unsigned long flags;
> +
> +       spin_lock_irqsave(&bcm_kona_gpio.lock, flags);
> +       bcm_kona_gpio_unlock_bank(bank_id);
> +
> +       /* determine the GPIO pin direction */
> +       val = readl(reg_base + bcm_kona_gpio_control(gpio));
> +       val &= GPIO_GPCTR0_IOTR_MASK;
> +
> +       /* this function only applies to output pin */
> +       if (GPIO_GPCTR0_IOTR_CMD_INPUT == val)
> +               return;
> +
> +       reg_offset = value ? bcm_kona_gpio_out_set(bank_id) :
> +                               bcm_kona_gpio_out_clear(bank_id);
> +
> +       val = readl(reg_base + reg_offset);
> +       val |= 1 << bit;
> +       writel(val, reg_base + reg_offset);
> +
> +       bcm_kona_gpio_lock_bank(bank_id);
> +       spin_unlock_irqrestore(&bcm_kona_gpio.lock, flags);
> +}
> +
> +static int bcm_kona_gpio_get(struct gpio_chip *chip, unsigned gpio)
> +{
> +       int bank_id = GPIO_BANK(gpio);
> +       int bit = GPIO_BIT(gpio);
> +       void __iomem *reg_base = bcm_kona_gpio.reg_base;
> +       u32 val, reg_offset;
> +       unsigned long flags;
> +
> +       spin_lock_irqsave(&bcm_kona_gpio.lock, flags);
> +       bcm_kona_gpio_unlock_bank(bank_id);
> +
> +       /* determine the GPIO pin direction */
> +       val = readl(reg_base + bcm_kona_gpio_control(gpio));
> +       val &= GPIO_GPCTR0_IOTR_MASK;
> +
> +       /* read the GPIO bank status */
> +       reg_offset = (GPIO_GPCTR0_IOTR_CMD_INPUT == val) ?
> +                                       bcm_kona_gpio_in_status(bank_id) :
> +                                       bcm_kona_gpio_out_status(bank_id);
> +       val = readl(reg_base + reg_offset);
> +
> +       bcm_kona_gpio_lock_bank(bank_id);
> +       spin_unlock_irqrestore(&bcm_kona_gpio.lock, flags);
> +
> +       /* return the specified bit status */
> +       return (val >> bit) & 1;
> +}
> +
> +static int bcm_kona_gpio_direction_input(struct gpio_chip *chip,
> +       unsigned gpio)
> +{
> +       void __iomem *reg_base = bcm_kona_gpio.reg_base;
> +       u32 val;
> +       unsigned long flags;
> +       int bank_id = GPIO_BANK(gpio);
> +
> +       spin_lock_irqsave(&bcm_kona_gpio.lock, flags);
> +       bcm_kona_gpio_unlock_bank(bank_id);
> +
> +       val = readl(reg_base + bcm_kona_gpio_control(gpio));
> +       val &= ~GPIO_GPCTR0_IOTR_MASK;
> +       val |= GPIO_GPCTR0_IOTR_CMD_INPUT;
> +       writel(val, reg_base + bcm_kona_gpio_control(gpio));
> +
> +       bcm_kona_gpio_lock_bank(bank_id);
> +       spin_unlock_irqrestore(&bcm_kona_gpio.lock, flags);
> +
> +       return 0;
> +}
> +
> +static int bcm_kona_gpio_direction_output(struct gpio_chip *chip,
> +       unsigned gpio, int value)
> +{
> +       void __iomem *reg_base = bcm_kona_gpio.reg_base;
> +       int bank_id = GPIO_BANK(gpio);
> +       int bit = GPIO_BIT(gpio);
> +       u32 val, reg_offset;
> +       unsigned long flags;
> +
> +       spin_lock_irqsave(&bcm_kona_gpio.lock, flags);
> +       bcm_kona_gpio_unlock_bank(bank_id);
> +
> +       val = readl(reg_base + bcm_kona_gpio_control(gpio));
> +       val &= ~GPIO_GPCTR0_IOTR_MASK;
> +       val |= GPIO_GPCTR0_IOTR_CMD_0UTPUT;
> +       writel(val, reg_base + bcm_kona_gpio_control(gpio));
> +       reg_offset = value ? bcm_kona_gpio_out_set(bank_id) :
> +                               bcm_kona_gpio_out_clear(bank_id);
> +
> +       val = readl(reg_base + reg_offset);
> +       val |= 1 << bit;
> +       writel(val, reg_base + reg_offset);
> +
> +       bcm_kona_gpio_lock_bank(bank_id);
> +       spin_unlock_irqrestore(&bcm_kona_gpio.lock, flags);
> +
> +       return 0;
> +}
> +
> +static int bcm_kona_gpio_to_irq(struct gpio_chip *chip, unsigned gpio)
> +{
> +       if (gpio >= bcm_gpio_chip.ngpio)
is bcm_gpio_chip != chip ?
Globals are even if you have that value passed as argument ?

> +               return -ENXIO;
> +       return irq_create_mapping(bcm_kona_gpio.irq_domain, gpio);
> +}
> +
> +static int bcm_kona_gpio_set_debounce(struct gpio_chip *chip, unsigned gpio,
> +       unsigned debounce)
> +{
> +       void __iomem *reg_base = bcm_kona_gpio.reg_base;
> +       u32 val, res;
> +       unsigned long flags;
> +       int bank_id = GPIO_BANK(gpio);
> +
> +       /* debounce must be 1-128ms (or 0) */
> +       if ((debounce > 0 && debounce < 1000) || debounce > 128000) {
> +               dev_err(chip->dev, "Debounce value %u not in range\n",
> +                       debounce);
> +               return -EINVAL;
> +       }
> +
> +       /* calculate debounce bit value */
> +       if (debounce != 0) {
> +               /* Convert to ms */
> +               debounce /= 1000;
> +
> +               /* find the MSB */
> +               res = fls(debounce) - 1;
> +
> +               /* Check if MSB-1 is set (round up or down) */
> +               if (res > 0 && (debounce & 1 << (res - 1)))
> +                       res++;
> +       }
> +
> +       /* spin lock for read-modify-write of the GPIO register */
> +       spin_lock_irqsave(&bcm_kona_gpio.lock, flags);
> +       bcm_kona_gpio_unlock_bank(bank_id);
> +
> +       val = readl(reg_base + bcm_kona_gpio_control(gpio));
> +       val &= ~GPIO_GPCTR0_DBR_MASK;
> +
> +       if (debounce == 0) {
> +               /* disable debounce */
> +               val &= ~GPIO_GPCTR0_DB_ENABLE_MASK;
> +       } else {
> +               val |= GPIO_GPCTR0_DB_ENABLE_MASK |
> +                         (res << GPIO_GPCTR0_DBR_SHIFT);
> +       }
> +
> +       writel(val, reg_base + bcm_kona_gpio_control(gpio));
> +
> +       bcm_kona_gpio_lock_bank(bank_id);
> +       spin_unlock_irqrestore(&bcm_kona_gpio.lock, flags);
> +
> +       return 0;
> +}
> +
> +static int bcm_kona_gpio_request(struct gpio_chip *chip, unsigned gpio)
> +{
> +       struct irq_data d;
> +
> +       d.hwirq = gpio;
> +       bcm_kona_gpio_irq_unmask(&d);
> +
> +       return 0;
> +}
> +
> +static void bcm_kona_gpio_free(struct gpio_chip *chip, unsigned gpio)
> +{
> +       struct irq_data d;
> +
> +       d.hwirq = gpio;
> +       bcm_kona_gpio_irq_mask(&d);
> +}
> +
> +static struct gpio_chip bcm_gpio_chip = {
> +       .label = "bcm-kona-gpio",
> +       .request = bcm_kona_gpio_request,
> +       .free = bcm_kona_gpio_free,
> +       .direction_input = bcm_kona_gpio_direction_input,
> +       .get = bcm_kona_gpio_get,
> +       .direction_output = bcm_kona_gpio_direction_output,
> +       .set = bcm_kona_gpio_set,
> +       .set_debounce = bcm_kona_gpio_set_debounce,
> +       .to_irq = bcm_kona_gpio_to_irq,
> +       .base = 0,
> +};
> +
> +static void bcm_kona_gpio_irq_ack(struct irq_data *d)
> +{
> +       int gpio = d->hwirq;
> +       int bank_id = GPIO_BANK(gpio);
> +       int bit = GPIO_BIT(gpio);
> +       void __iomem *reg_base = bcm_kona_gpio.reg_base;
> +       u32 val;
> +       unsigned long flags;
> +
> +       spin_lock_irqsave(&bcm_kona_gpio.lock, flags);
> +       bcm_kona_gpio_unlock_bank(bank_id);
> +
> +       val = readl(reg_base + bcm_kona_gpio_int_status(bank_id));
> +       val |= 1 << bit;
> +       writel(val, reg_base + bcm_kona_gpio_int_status(bank_id));
> +
> +       bcm_kona_gpio_lock_bank(bank_id);
> +       spin_unlock_irqrestore(&bcm_kona_gpio.lock, flags);
> +}
> +
> +static void bcm_kona_gpio_irq_mask(struct irq_data *d)
> +{
> +       int gpio = d->hwirq;
> +       int bank_id = GPIO_BANK(gpio);
> +       int bit = GPIO_BIT(gpio);
> +       void __iomem *reg_base = bcm_kona_gpio.reg_base;
> +       u32 val;
> +       unsigned long flags;
> +
> +       spin_lock_irqsave(&bcm_kona_gpio.lock, flags);
> +       bcm_kona_gpio_unlock_bank(bank_id);
> +
> +       val = readl(reg_base + bcm_kona_gpio_int_mask(bank_id));
> +       val |= 1 << bit;
> +       writel(val, reg_base + bcm_kona_gpio_int_mask(bank_id));
> +
> +       bcm_kona_gpio_lock_bank(bank_id);
> +       spin_unlock_irqrestore(&bcm_kona_gpio.lock, flags);
> +}
> +
> +static void bcm_kona_gpio_irq_unmask(struct irq_data *d)
> +{
> +       int gpio = d->hwirq;
> +       int bank_id = GPIO_BANK(gpio);
> +       int bit = GPIO_BIT(gpio);
> +       void __iomem *reg_base = bcm_kona_gpio.reg_base;
> +       u32 val;
> +       unsigned long flags;
> +
> +       spin_lock_irqsave(&bcm_kona_gpio.lock, flags);
> +       bcm_kona_gpio_unlock_bank(bank_id);
> +
> +       val = readl(reg_base + bcm_kona_gpio_int_mskclr(bank_id));
> +       val |= 1 << bit;
> +       writel(val, reg_base + bcm_kona_gpio_int_mskclr(bank_id));
> +
> +       bcm_kona_gpio_lock_bank(bank_id);
> +       spin_unlock_irqrestore(&bcm_kona_gpio.lock, flags);
> +}
> +
> +static int bcm_kona_gpio_irq_set_type(struct irq_data *d, unsigned int type)
> +{
> +       int gpio = d->hwirq;
> +       void __iomem *reg_base = bcm_kona_gpio.reg_base;
irq_*_get_irq_chip_* series of helpers will be useful in these case
You have chip, chip_data, handler_data in irq_data to avoid all these
global data.

> +       u32 lvl_type;
> +       u32 val;
> +       unsigned long flags;
> +       int bank_id = GPIO_BANK(gpio);
> +
> +       switch (type & IRQ_TYPE_SENSE_MASK) {
> +       case IRQ_TYPE_EDGE_RISING:
> +               lvl_type = GPIO_GPCTR0_ITR_CMD_RISING_EDGE;
> +               break;
> +
> +       case IRQ_TYPE_EDGE_FALLING:
> +               lvl_type = GPIO_GPCTR0_ITR_CMD_FALLING_EDGE;
> +               break;
> +
> +       case IRQ_TYPE_EDGE_BOTH:
> +               lvl_type = GPIO_GPCTR0_ITR_CMD_BOTH_EDGE;
> +               break;
> +
> +       case IRQ_TYPE_LEVEL_HIGH:
> +       case IRQ_TYPE_LEVEL_LOW:
> +               /* BCM GPIO doesn't support level triggering */
> +       default:
> +               dev_err(bcm_gpio_chip.dev, "Invalid BCM GPIO irq type 0x%x\n",
> +                       type);
> +               return -EINVAL;
> +       }
> +
> +       spin_lock_irqsave(&bcm_kona_gpio.lock, flags);
> +       bcm_kona_gpio_unlock_bank(bank_id);
> +
> +       val = readl(reg_base + bcm_kona_gpio_control(gpio));
> +       val &= ~GPIO_GPCTR0_ITR_MASK;
> +       val |= lvl_type << GPIO_GPCTR0_ITR_SHIFT;
> +       writel(val, reg_base + bcm_kona_gpio_control(gpio));
> +
> +       bcm_kona_gpio_lock_bank(bank_id);
> +       spin_unlock_irqrestore(&bcm_kona_gpio.lock, flags);
> +
> +       return 0;
> +}
> +
> +static void bcm_kona_gpio_irq_handler(unsigned int irq, struct irq_desc *desc)
> +{
> +       int bit, bank_id;
> +       void __iomem *reg_base = bcm_kona_gpio.reg_base;
> +       unsigned long sta;
> +       struct bcm_kona_gpio_bank *bank = irq_get_handler_data(irq);
> +       struct irq_chip *chip = irq_desc_get_chip(desc);
> +
> +       chained_irq_enter(chip, desc);
> +
> +       bank_id = bank->id;
> +       bcm_kona_gpio_unlock_bank(bank_id);
> +
> +       sta = readl(reg_base + bcm_kona_gpio_int_status(bank_id)) &
> +           (~(readl(reg_base + bcm_kona_gpio_int_mask(bank_id))));
> +
> +       for_each_set_bit(bit, &sta, 32) {
> +               /*
> +                * Clear interrupt before handler is called so we don't
> +                * miss any interrupt occurred during executing them.
> +                */
> +               writel(readl(reg_base + bcm_kona_gpio_int_status(bank_id)) |
> +                               (1 << bit),
> +                               reg_base + bcm_kona_gpio_int_status(bank_id));
> +
> +               /* Invoke interrupt handler */
> +               generic_handle_irq(gpio_to_irq(GPIO_PER_BANK * bank_id + bit));
> +       }
> +
> +       bcm_kona_gpio_lock_bank(bank_id);
> +
> +       chained_irq_exit(chip, desc);
> +}
> +
> +static struct irq_chip bcm_gpio_irq_chip = {
> +       .name = "bcm-kona-gpio",
> +       .irq_ack = bcm_kona_gpio_irq_ack,
> +       .irq_mask = bcm_kona_gpio_irq_mask,
> +       .irq_unmask = bcm_kona_gpio_irq_unmask,
> +       .irq_set_type = bcm_kona_gpio_irq_set_type,
> +};
> +
> +static struct __initconst of_device_id bcm_kona_gpio_of_match[] = {
> +       { .compatible = "brcm,kona-gpio" },
> +       {}
> +};
> +MODULE_DEVICE_TABLE(of, kona_gpio_match);
> +
> +/*
> + * 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;
> +
> +static int bcm_kona_gpio_irq_map(struct irq_domain *d, unsigned int virq,
> +                               irq_hw_number_t hwirq)
> +{
> +       irq_set_chip_data(virq, &d->host_data);
> +       irq_set_lockdep_class(virq, &gpio_lock_class);
> +       irq_set_chip_and_handler(virq, &bcm_gpio_irq_chip, handle_simple_irq);
> +       irq_set_nested_thread(virq, 1);
> +       set_irq_flags(virq, IRQF_VALID);
> +
> +       return 0;
> +}
> +
> +static void bcm_kona_gpio_irq_unmap(struct irq_domain *d, unsigned int virq)
> +{
> +       irq_set_chip_and_handler(virq, NULL, NULL);
> +       irq_set_chip_data(virq, NULL);
> +}
> +
> +static struct irq_domain_ops bcm_kona_irq_ops = {
> +       .map    = bcm_kona_gpio_irq_map,
> +       .unmap  = bcm_kona_gpio_irq_unmap,
> +       .xlate  = irq_domain_xlate_twocell,
> +};
> +
> +static void bcm_kona_gpio_reset(int num_bank)
> +{
> +       int i;
> +       void __iomem *reg_base = bcm_kona_gpio.reg_base;
> +
> +       /* disable interrupts and clear status */
> +       for (i = 0; i < num_bank; i++) {
> +               bcm_kona_gpio_unlock_bank(i);
> +               writel(0xFFFFFFFF, reg_base + bcm_kona_gpio_int_mask(i));
> +               writel(0xFFFFFFFF, reg_base + bcm_kona_gpio_int_status(i));
> +               bcm_kona_gpio_lock_bank(i);
> +       }
> +}
> +
> +static int bcm_kona_gpio_probe(struct platform_device *pdev)
> +{
> +       const struct of_device_id *match;
> +       struct resource *res;
> +       struct bcm_kona_gpio_bank *bank;
> +       int ret;
> +       int i;
> +
> +       match = of_match_device(bcm_kona_gpio_of_match, &pdev->dev);
> +       if (!match) {
> +               dev_err(&pdev->dev, "Failed to find gpio controller\n");
> +               return -ENODEV;
> +       }
> +
> +       bcm_kona_gpio.num_bank = bcm_kona_count_irq_resources(pdev);
> +       if (bcm_kona_gpio.num_bank == 0) {
> +               dev_err(&pdev->dev, "Couldn't determine # GPIO banks\n");
> +               return -ENOENT;
> +       }
> +       bcm_gpio_chip.of_node = pdev->dev.of_node;
> +       bcm_gpio_chip.dev = &pdev->dev;
> +       bcm_gpio_chip.ngpio = bcm_kona_gpio.num_bank * GPIO_PER_BANK;
> +       bcm_kona_gpio.banks = devm_kzalloc(&pdev->dev,
> +                                      bcm_kona_gpio.num_bank *
> +                                      sizeof(*bcm_kona_gpio.banks),
> +                                      GFP_KERNEL);
> +       if (!bcm_kona_gpio.banks) {
> +               dev_err(&pdev->dev, "Couldn't allocate bank structure\n");
> +               return -ENOMEM;
> +       }
> +
> +       bcm_kona_gpio.irq_base = irq_alloc_descs(-1, 0, bcm_gpio_chip.ngpio,
> +                                               0);
> +       if (bcm_kona_gpio.irq_base < 0) {
> +               dev_err(&pdev->dev, "Couldn't allocate IRQ numbers\n");
> +               return -ENXIO;
> +       }
> +       bcm_kona_gpio.irq_domain = irq_domain_add_linear(pdev->dev.of_node,
> +                                               bcm_gpio_chip.ngpio,
> +                                               &bcm_kona_irq_ops,
> +                                               &bcm_kona_gpio);
> +       if (!bcm_kona_gpio.irq_domain) {
> +               dev_err(&pdev->dev, "Couldn't allocate IRQ domain\n");
> +               ret = -ENXIO;
> +               goto err_irq_descs;
> +       }
> +       for (i = 0; i < bcm_kona_gpio.num_bank; i++) {
> +               bank = &bcm_kona_gpio.banks[i];
> +               bank->id = i;
> +               bank->irq = platform_get_irq(pdev, i);
> +               if (bank->irq < 0) {
> +                       dev_err(&pdev->dev, "Couldn't get IRQ for bank %d", i);
> +                       ret = -ENOENT;
> +                       goto err_irq_domain;
> +               }
> +       }
> +
> +       res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +       if (!res) {
> +               dev_err(&pdev->dev, "Missing MEM resource\n");
> +               ret = -ENXIO;
> +               goto err_irq_domain;
> +       }
> +
> +       bcm_kona_gpio.reg_base = devm_request_and_ioremap(&pdev->dev, res);
> +       if (!bcm_kona_gpio.reg_base) {
> +               dev_err(&pdev->dev, "Couldn't ioremap regs\n");
> +               ret = -ENXIO;
> +               goto err_irq_domain;
> +       }
> +       dev_info(&pdev->dev, "Setting up Kona GPIO at 0x%p (phys %#x)\n",
> +               bcm_kona_gpio.reg_base, res->start);
> +
> +       bcm_kona_gpio_reset(bcm_kona_gpio.num_bank);
> +
> +       ret = gpiochip_add(&bcm_gpio_chip);
> +       if (ret < 0) {
> +               dev_err(&pdev->dev, "Couldn't add GPIO chip -- %d\n", ret);
> +               goto err_irq_domain;
> +       }
> +       for (i = 0; i < bcm_gpio_chip.ngpio; i++) {
> +               int irq = bcm_kona_gpio_to_irq(&bcm_gpio_chip, i);
> +               bank = &bcm_kona_gpio.banks[GPIO_BANK(i)];
> +               irq_set_lockdep_class(irq, &gpio_lock_class);
> +               irq_set_chip_data(irq, bank);
> +               irq_set_chip_and_handler(irq, &bcm_gpio_irq_chip,
> +                                        handle_simple_irq);
> +               set_irq_flags(irq, IRQF_VALID);
> +       }
> +       for (i = 0; i < bcm_kona_gpio.num_bank; i++) {
> +               bank = &bcm_kona_gpio.banks[i];
> +
> +               irq_set_chained_handler(bank->irq, bcm_kona_gpio_irq_handler);
> +               irq_set_handler_data(bank->irq, bank);
> +       }
> +
> +       spin_lock_init(&bcm_kona_gpio.lock);
> +
platform_set_drvdata to set it as bcm_kona_gpio so that you need not
access the global pointer anywhere else. In fact it can removed I think.

> +       return 0;
> +
> +err_irq_domain:
> +       irq_domain_remove(bcm_kona_gpio.irq_domain);
> +
> +err_irq_descs:
> +       irq_free_descs(bcm_kona_gpio.irq_base, bcm_gpio_chip.ngpio);
> +
> +       return ret;
> +}
> +
> +static int bcm_kona_gpio_remove(struct platform_device *pdev)
> +{
> +       int i, ret;
> +       struct bcm_kona_gpio_bank *bank;
> +
> +       for (i = 0; i < bcm_gpio_chip.ngpio; i++)
may be bcm_kona_gpio as driver data will help here ?

> +               gpio_free(i);
> +       ret = gpiochip_remove(&bcm_gpio_chip);
> +       if (ret < 0) {
> +               dev_err(&pdev->dev, "Couldn't remove GPIO chip -- %d\n", ret);
> +               return ret;
> +       }
> +       for (i = 0; i < bcm_kona_gpio.num_bank; i++) {
> +               bank = &bcm_kona_gpio.banks[i];
> +               irq_set_chained_handler(bank->irq, NULL);
> +               irq_set_handler_data(bank->irq, NULL);
> +       }
> +       irq_domain_remove(bcm_kona_gpio.irq_domain);
> +       irq_free_descs(bcm_kona_gpio.irq_base, bcm_gpio_chip.ngpio);
> +
> +       return 0;
> +}
> +
> +static struct platform_driver bcm_kona_gpio_driver = {
> +       .driver = {
> +                  .name = "bcm-kona-gpio",
> +                  .owner = THIS_MODULE,
> +                  .of_match_table = bcm_kona_gpio_of_match,
> +                  },
> +       .probe = bcm_kona_gpio_probe,
> +       .remove = bcm_kona_gpio_remove,
> +};
> +
> +module_platform_driver(bcm_kona_gpio_driver);
> +
> +MODULE_AUTHOR("Broadcom");
> +MODULE_DESCRIPTION("Broadcom Kona GPIO Driver");
> +MODULE_LICENSE("GPL v2");

IMO, you don't require any global data or pointers if probe populates
all the pdev, irq/gpio_chip data member appropriately

Regards,
Sudeep