Re: [PATCH v12] gpio: add a driver for the Synopsys DesignWare APB GPIO block

[Dinh Nguyen <dinh.linux@xxxxxxxxx>]

Hi Alan,

On Wed, 2014-02-26 at 09:53 -0600, delicious quinoa wrote:
> On Tue, Feb 25, 2014 at 5:01 PM, Alan Tull <delicious.quinoa@xxxxxxxxx> wrote:
> > From: Jamie Iles <jamie@xxxxxxxxxxxxx>
> >
> > The Synopsys DesignWare block is used in some ARM devices (picoxcell)
> > and can be configured to provide multiple banks of GPIO pins.
> >
> > Signed-off-by: Jamie Iles <jamie@xxxxxxxxxxxxx>
> > Signed-off-by: Alan Tull <atull@xxxxxxxxxx>
> > Reviewed-by: Sebastian Hesselbarth <sebastian.hesselbarth@xxxxxxxxx>
> >
> > v12: - Add irq_startup/shutdown
> >      - do irq_create_mapping() in probe, irq_find_mapping() in to_irq()
> >      - Adjust mappings to show support for 1 gpio per port.
> >      - gpio-cells = <1>
> > v11: - Use NULL when checking existence of 'interrupts' property
> >      - Bindings descriptions cleanup
> > v10: - in documentation nr-gpio -> nr-gpios
> > v9:  - cleanup in dt bindings doc
> >      - use of_get_child_count()
> > v8:  - remove socfpga.dtsi changes
> >      - minor cleanup in devicetree documentation
> > v7:  - use irq_generic_chip
> >      - support one irq per gpio line or one irq for many
> >      - s/bank/port/ and other cleanup
> > v6:  - (atull) squash the set of patches
> >      - use linear irq domain
> >      - build fixes. Original driver was reviewed on v3.2.
> >      - Fix setting irq edge type for 'rising' and 'both'.
> >      - Support as a loadable module.
> >      - Use bgpio_chip's spinlock during register access.
> >      - Clean up register names to match spec
> >      - s/bank/port/ because register names use the word 'port'
> >      - s/nr-gpio/nr-gpios/
> >      - don't get/put the of_node
> >      - remove signoffs/acked-by's because of changes
> >      - other cleanup
> > v5:  - handle sparse bank population correctly
> > v3:  - depend on rather than select IRQ_DOMAIN
> >      - split IRQ support into a separate patch
> > v2:  - use Rob Herring's irqdomain in generic irq chip patches
> >      - use reg property to indicate bank index
> >      - support irqs on both edges based on LinusW's u300 driver
> > ---
> >  .../devicetree/bindings/gpio/snps-dwapb-gpio.txt   |   57 +++
> >  drivers/gpio/Kconfig                               |    9 +
> >  drivers/gpio/Makefile                              |    1 +
> >  drivers/gpio/gpio-dwapb.c                          |  438 ++++++++++++++++++++
> >  4 files changed, 505 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/gpio/snps-dwapb-gpio.txt
> >  create mode 100644 drivers/gpio/gpio-dwapb.c
> >
> > diff --git a/Documentation/devicetree/bindings/gpio/snps-dwapb-gpio.txt b/Documentation/devicetree/bindings/gpio/snps-dwapb-gpio.txt
> > new file mode 100644
> > index 0000000..0934950
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/gpio/snps-dwapb-gpio.txt
> > @@ -0,0 +1,57 @@
> > +* Synopsys DesignWare APB GPIO controller
> > +
> > +Required properties:
> > +- compatible : Should contain "snps,dw-apb-gpio"
> > +- reg : Address and length of the register set for the device.
> > +- #address-cells : should be 1 (for addressing port subnodes).
> > +- #size-cells : should be 0 (port subnodes).
> > +
> > +The GPIO controller has a configurable number of ports, each of which are
> > +represented as child nodes with the following properties:
> > +
> > +Required properties:
> > +- compatible : "snps,dw-apb-gpio-port"
> > +- gpio-controller : Marks the device node as a gpio controller.
> > +- #gpio-cells : Should be 1.  It is the pin number.
> > +- reg : The integer port index of the port, a single cell.
> > +
> > +Optional properties:
> > +- interrupt-controller : The first port may be configured to be an interrupt
> > +controller.
> > +- #interrupt-cells : Specifies the number of cells needed to encode an
> > +  interrupt.  Shall be set to 2.  The first cell defines the interrupt number,
> > +  the second encodes the triger flags encoded as described in
> > +  Documentation/devicetree/bindings/interrupts.txt
> > +- interrupt-parent : The parent interrupt controller.
> > +- interrupts : The interrupt to the parent controller raised when GPIOs
> > +  generate the interrupts.
> > +- snps,nr-gpios : The number of pins in the port, a single cell.
> > +
> > +Example:
> > +
> > +gpio: gpio@20000 {
> > +       compatible = "snps,dw-apb-gpio";
> > +       reg = <0x20000 0x1000>;
> > +       #address-cells = <1>;
> > +       #size-cells = <0>;
> > +
> > +       porta: gpio-controller@0 {
> > +               compatible = "snps,dw-apb-gpio-port";
> > +               gpio-controller;
> > +               #gpio-cells = <1>;
> > +               snps,nr-gpios = <8>;
> > +               reg = <0>;
> > +               interrupt-controller;
> > +               #interrupt-cells = <2>;
> > +               interrupt-parent = <&vic1>;
> > +               interrupts = <0>;
> > +       };
> > +
> > +       portb: gpio-controller@1 {
> > +               compatible = "snps,dw-apb-gpio-port";
> > +               gpio-controller;
> > +               #gpio-cells = <1>;
> > +               snps,nr-gpios = <8>;
> > +               reg = <1>;
> > +       };
> > +};
> 
> Hi Rob,
> 
> Are these bindings acceptable?

In the future, I think you should split out the DTS documentation into a
separate patch. As recommended in :

Documentation/devicetree/bindings/submitting-patches.txt

Dinh
> 
> Alan
> 
> > diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
> > index 903f24d..9979017 100644
> > --- a/drivers/gpio/Kconfig
> > +++ b/drivers/gpio/Kconfig
> > @@ -128,6 +128,15 @@ config GPIO_GENERIC_PLATFORM
> >         help
> >           Say yes here to support basic platform_device memory-mapped GPIO controllers.
> >
> > +config GPIO_DWAPB
> > +       tristate "Synopsys DesignWare APB GPIO driver"
> > +       select GPIO_GENERIC
> > +       select GENERIC_IRQ_CHIP
> > +       depends on OF_GPIO && IRQ_DOMAIN
> > +       help
> > +         Say Y or M here to build support for the Synopsys DesignWare APB
> > +         GPIO block.
> > +
> >  config GPIO_IT8761E
> >         tristate "IT8761E GPIO support"
> >         depends on X86  # unconditional access to IO space.
> > diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
> > index 5d50179..2d09f04 100644
> > --- a/drivers/gpio/Makefile
> > +++ b/drivers/gpio/Makefile
> > @@ -23,6 +23,7 @@ obj-$(CONFIG_GPIO_CS5535)     += gpio-cs5535.o
> >  obj-$(CONFIG_GPIO_DA9052)      += gpio-da9052.o
> >  obj-$(CONFIG_GPIO_DA9055)      += gpio-da9055.o
> >  obj-$(CONFIG_GPIO_DAVINCI)     += gpio-davinci.o
> > +obj-$(CONFIG_GPIO_DWAPB)       += gpio-dwapb.o
> >  obj-$(CONFIG_GPIO_EM)          += gpio-em.o
> >  obj-$(CONFIG_GPIO_EP93XX)      += gpio-ep93xx.o
> >  obj-$(CONFIG_GPIO_F7188X)      += gpio-f7188x.o
> > diff --git a/drivers/gpio/gpio-dwapb.c b/drivers/gpio/gpio-dwapb.c
> > new file mode 100644
> > index 0000000..2797fbb
> > --- /dev/null
> > +++ b/drivers/gpio/gpio-dwapb.c
> > @@ -0,0 +1,438 @@
> > +/*
> > + * Copyright (c) 2011 Jamie Iles
> > + *
> > + * This program is free software; you can redistribute it and/or modify
> > + * it under the terms of the GNU General Public License version 2 as
> > + * published by the Free Software Foundation.
> > + *
> > + * All enquiries to support@xxxxxxxxxxxx
> > + */
> > +#include <linux/basic_mmio_gpio.h>
> > +#include <linux/err.h>
> > +#include <linux/init.h>
> > +#include <linux/interrupt.h>
> > +#include <linux/io.h>
> > +#include <linux/ioport.h>
> > +#include <linux/irq.h>
> > +#include <linux/irqdomain.h>
> > +#include <linux/module.h>
> > +#include <linux/of.h>
> > +#include <linux/of_address.h>
> > +#include <linux/of_irq.h>
> > +#include <linux/platform_device.h>
> > +#include <linux/spinlock.h>
> > +
> > +#define GPIO_SWPORTA_DR                0x00
> > +#define GPIO_SWPORTA_DDR       0x04
> > +#define GPIO_SWPORTB_DR                0x0c
> > +#define GPIO_SWPORTB_DDR       0x10
> > +#define GPIO_SWPORTC_DR                0x18
> > +#define GPIO_SWPORTC_DDR       0x1c
> > +#define GPIO_SWPORTD_DR                0x24
> > +#define GPIO_SWPORTD_DDR       0x28
> > +#define GPIO_INTEN             0x30
> > +#define GPIO_INTMASK           0x34
> > +#define GPIO_INTTYPE_LEVEL     0x38
> > +#define GPIO_INT_POLARITY      0x3c
> > +#define GPIO_INTSTATUS         0x40
> > +#define GPIO_PORTA_EOI         0x4c
> > +#define GPIO_EXT_PORTA         0x50
> > +#define GPIO_EXT_PORTB         0x54
> > +#define GPIO_EXT_PORTC         0x58
> > +#define GPIO_EXT_PORTD         0x5c
> > +
> > +#define DWAPB_MAX_PORTS                4
> > +#define GPIO_EXT_PORT_SIZE     (GPIO_EXT_PORTB - GPIO_EXT_PORTA)
> > +#define GPIO_SWPORT_DR_SIZE    (GPIO_SWPORTB_DR - GPIO_SWPORTA_DR)
> > +#define GPIO_SWPORT_DDR_SIZE   (GPIO_SWPORTB_DDR - GPIO_SWPORTA_DDR)
> > +
> > +struct dwapb_gpio;
> > +
> > +struct dwapb_gpio_port {
> > +       struct bgpio_chip       bgc;
> > +       bool                    is_registered;
> > +       struct dwapb_gpio       *gpio;
> > +};
> > +
> > +struct dwapb_gpio {
> > +       struct  device          *dev;
> > +       void __iomem            *regs;
> > +       struct dwapb_gpio_port  *ports;
> > +       unsigned int            nr_ports;
> > +       struct irq_domain       *domain;
> > +};
> > +
> > +static int dwapb_gpio_to_irq(struct gpio_chip *gc, unsigned offset)
> > +{
> > +       struct bgpio_chip *bgc = to_bgpio_chip(gc);
> > +       struct dwapb_gpio_port *port = container_of(bgc, struct
> > +                                                   dwapb_gpio_port, bgc);
> > +       struct dwapb_gpio *gpio = port->gpio;
> > +
> > +       return irq_find_mapping(gpio->domain, offset);
> > +}
> > +
> > +static void dwapb_toggle_trigger(struct dwapb_gpio *gpio, unsigned int offs)
> > +{
> > +       u32 v = readl(gpio->regs + GPIO_INT_POLARITY);
> > +
> > +       if (gpio_get_value(gpio->ports[0].bgc.gc.base + offs))
> > +               v &= ~BIT(offs);
> > +       else
> > +               v |= BIT(offs);
> > +
> > +       writel(v, gpio->regs + GPIO_INT_POLARITY);
> > +}
> > +
> > +static void dwapb_irq_handler(u32 irq, struct irq_desc *desc)
> > +{
> > +       struct dwapb_gpio *gpio = irq_get_handler_data(irq);
> > +       struct irq_chip *chip = irq_desc_get_chip(desc);
> > +       u32 irq_status = readl_relaxed(gpio->regs + GPIO_INTSTATUS);
> > +
> > +       while (irq_status) {
> > +               int hwirq = fls(irq_status) - 1;
> > +               int gpio_irq = irq_find_mapping(gpio->domain, hwirq);
> > +
> > +               generic_handle_irq(gpio_irq);
> > +               irq_status &= ~BIT(hwirq);
> > +
> > +               if ((irq_get_trigger_type(gpio_irq) & IRQ_TYPE_SENSE_MASK)
> > +                       == IRQ_TYPE_EDGE_BOTH)
> > +                       dwapb_toggle_trigger(gpio, hwirq);
> > +       }
> > +
> > +       if (chip->irq_eoi)
> > +               chip->irq_eoi(irq_desc_get_irq_data(desc));
> > +}
> > +
> > +static void dwapb_irq_enable(struct irq_data *d)
> > +{
> > +       struct irq_chip_generic *igc = irq_data_get_irq_chip_data(d);
> > +       struct dwapb_gpio *gpio = igc->private;
> > +       struct bgpio_chip *bgc = &gpio->ports[0].bgc;
> > +       unsigned long flags;
> > +       u32 val;
> > +
> > +       spin_lock_irqsave(&bgc->lock, flags);
> > +       val = readl(gpio->regs + GPIO_INTEN);
> > +       val |= BIT(d->hwirq);
> > +       writel(val, gpio->regs + GPIO_INTEN);
> > +       spin_unlock_irqrestore(&bgc->lock, flags);
> > +}
> > +
> > +static void dwapb_irq_disable(struct irq_data *d)
> > +{
> > +       struct irq_chip_generic *igc = irq_data_get_irq_chip_data(d);
> > +       struct dwapb_gpio *gpio = igc->private;
> > +       struct bgpio_chip *bgc = &gpio->ports[0].bgc;
> > +       unsigned long flags;
> > +       u32 val;
> > +
> > +       spin_lock_irqsave(&bgc->lock, flags);
> > +       val = readl(gpio->regs + GPIO_INTEN);
> > +       val &= ~BIT(d->hwirq);
> > +       writel(val, gpio->regs + GPIO_INTEN);
> > +       spin_unlock_irqrestore(&bgc->lock, flags);
> > +}
> > +
> > +static unsigned int dwapb_irq_startup(struct irq_data *d)
> > +{
> > +       struct irq_chip_generic *igc = irq_data_get_irq_chip_data(d);
> > +       struct dwapb_gpio *gpio = igc->private;
> > +       struct bgpio_chip *bgc = &gpio->ports[0].bgc;
> > +
> > +       if (gpio_lock_as_irq(&bgc->gc, irqd_to_hwirq(d)))
> > +               dev_err(gpio->dev, "unable to lock HW IRQ %lu for IRQ\n",
> > +                       irqd_to_hwirq(d));
> > +       dwapb_irq_enable(d);
> > +       return 0;
> > +}
> > +
> > +static void dwapb_irq_shutdown(struct irq_data *d)
> > +{
> > +       struct irq_chip_generic *igc = irq_data_get_irq_chip_data(d);
> > +       struct dwapb_gpio *gpio = igc->private;
> > +       struct bgpio_chip *bgc = &gpio->ports[0].bgc;
> > +
> > +       dwapb_irq_disable(d);
> > +       gpio_unlock_as_irq(&bgc->gc, irqd_to_hwirq(d));
> > +}
> > +
> > +static int dwapb_irq_set_type(struct irq_data *d, u32 type)
> > +{
> > +       struct irq_chip_generic *igc = irq_data_get_irq_chip_data(d);
> > +       struct dwapb_gpio *gpio = igc->private;
> > +       struct bgpio_chip *bgc = &gpio->ports[0].bgc;
> > +       int bit = d->hwirq;
> > +       unsigned long level, polarity, flags;
> > +
> > +       if (type & ~(IRQ_TYPE_EDGE_RISING | IRQ_TYPE_EDGE_FALLING |
> > +                    IRQ_TYPE_LEVEL_HIGH | IRQ_TYPE_LEVEL_LOW))
> > +               return -EINVAL;
> > +
> > +       spin_lock_irqsave(&bgc->lock, flags);
> > +       level = readl(gpio->regs + GPIO_INTTYPE_LEVEL);
> > +       polarity = readl(gpio->regs + GPIO_INT_POLARITY);
> > +
> > +       switch (type) {
> > +       case IRQ_TYPE_EDGE_BOTH:
> > +               level |= BIT(bit);
> > +               dwapb_toggle_trigger(gpio, bit);
> > +               break;
> > +       case IRQ_TYPE_EDGE_RISING:
> > +               level |= BIT(bit);
> > +               polarity |= BIT(bit);
> > +               break;
> > +       case IRQ_TYPE_EDGE_FALLING:
> > +               level |= BIT(bit);
> > +               polarity &= ~BIT(bit);
> > +               break;
> > +       case IRQ_TYPE_LEVEL_HIGH:
> > +               level &= ~BIT(bit);
> > +               polarity |= BIT(bit);
> > +               break;
> > +       case IRQ_TYPE_LEVEL_LOW:
> > +               level &= ~BIT(bit);
> > +               polarity &= ~BIT(bit);
> > +               break;
> > +       }
> > +
> > +       writel(level, gpio->regs + GPIO_INTTYPE_LEVEL);
> > +       writel(polarity, gpio->regs + GPIO_INT_POLARITY);
> > +       spin_unlock_irqrestore(&bgc->lock, flags);
> > +
> > +       return 0;
> > +}
> > +
> > +static void dwapb_configure_irqs(struct dwapb_gpio *gpio,
> > +                                struct dwapb_gpio_port *port)
> > +{
> > +       struct gpio_chip *gc = &port->bgc.gc;
> > +       struct device_node *node =  gc->of_node;
> > +       struct irq_chip_generic *irq_gc;
> > +       unsigned int hwirq, ngpio = gc->ngpio;
> > +       struct irq_chip_type *ct;
> > +       int err, irq;
> > +
> > +       irq = irq_of_parse_and_map(node, 0);
> > +       if (!irq) {
> > +               dev_warn(gpio->dev, "no irq for bank %s\n",
> > +                       port->bgc.gc.of_node->full_name);
> > +               return;
> > +       }
> > +
> > +       gpio->domain = irq_domain_add_linear(node, ngpio,
> > +                                            &irq_generic_chip_ops, gpio);
> > +       if (!gpio->domain)
> > +               return;
> > +
> > +       err = irq_alloc_domain_generic_chips(gpio->domain, ngpio, 1,
> > +                                            "gpio-dwapb", handle_level_irq,
> > +                                            IRQ_NOREQUEST, 0,
> > +                                            IRQ_GC_INIT_NESTED_LOCK);
> > +       if (err) {
> > +               dev_info(gpio->dev, "irq_alloc_domain_generic_chips failed\n");
> > +               irq_domain_remove(gpio->domain);
> > +               gpio->domain = NULL;
> > +               return;
> > +       }
> > +
> > +       irq_gc = irq_get_domain_generic_chip(gpio->domain, 0);
> > +       if (!irq_gc) {
> > +               irq_domain_remove(gpio->domain);
> > +               gpio->domain = NULL;
> > +               return;
> > +       }
> > +
> > +       irq_gc->reg_base = gpio->regs;
> > +       irq_gc->private = gpio;
> > +
> > +       ct = irq_gc->chip_types;
> > +       ct->chip.irq_ack = irq_gc_ack_set_bit;
> > +       ct->chip.irq_mask = irq_gc_mask_set_bit;
> > +       ct->chip.irq_unmask = irq_gc_mask_clr_bit;
> > +       ct->chip.irq_set_type = dwapb_irq_set_type;
> > +       ct->chip.irq_enable = dwapb_irq_enable;
> > +       ct->chip.irq_disable = dwapb_irq_disable;
> > +       ct->chip.irq_startup = dwapb_irq_startup;
> > +       ct->chip.irq_shutdown = dwapb_irq_shutdown;
> > +       ct->regs.ack = GPIO_PORTA_EOI;
> > +       ct->regs.mask = GPIO_INTMASK;
> > +
> > +       irq_setup_generic_chip(irq_gc, IRQ_MSK(port->bgc.gc.ngpio),
> > +                       IRQ_GC_INIT_NESTED_LOCK, IRQ_NOREQUEST, 0);
> > +
> > +       irq_set_chained_handler(irq, dwapb_irq_handler);
> > +       irq_set_handler_data(irq, gpio);
> > +
> > +       for (hwirq = 0 ; hwirq < ngpio ; hwirq++)
> > +               irq_create_mapping(gpio->domain, hwirq);
> > +
> > +       port->bgc.gc.to_irq = dwapb_gpio_to_irq;
> > +}
> > +
> > +static void dwapb_irq_teardown(struct dwapb_gpio *gpio)
> > +{
> > +       struct dwapb_gpio_port *port = &gpio->ports[0];
> > +       struct gpio_chip *gc = &port->bgc.gc;
> > +       unsigned int ngpio = gc->ngpio;
> > +       irq_hw_number_t hwirq;
> > +
> > +       if (!gpio->domain)
> > +               return;
> > +
> > +       for (hwirq = 0 ; hwirq < ngpio ; hwirq++)
> > +               irq_dispose_mapping(irq_find_mapping(gpio->domain, hwirq));
> > +
> > +       irq_domain_remove(gpio->domain);
> > +       gpio->domain = NULL;
> > +}
> > +
> > +static int dwapb_gpio_add_port(struct dwapb_gpio *gpio,
> > +                              struct device_node *port_np,
> > +                              unsigned int offs)
> > +{
> > +       struct dwapb_gpio_port *port;
> > +       u32 port_idx, ngpio;
> > +       void __iomem *dat, *set, *dirout;
> > +       int err;
> > +
> > +       if (of_property_read_u32(port_np, "reg", &port_idx) ||
> > +               port_idx >= DWAPB_MAX_PORTS) {
> > +               dev_err(gpio->dev, "missing/invalid port index for %s\n",
> > +                       port_np->full_name);
> > +               return -EINVAL;
> > +       }
> > +
> > +       port = &gpio->ports[offs];
> > +       port->gpio = gpio;
> > +
> > +       if (of_property_read_u32(port_np, "snps,nr-gpios", &ngpio)) {
> > +               dev_info(gpio->dev, "failed to get number of gpios for %s\n",
> > +                        port_np->full_name);
> > +               ngpio = 32;
> > +       }
> > +
> > +       dat = gpio->regs + GPIO_EXT_PORTA + (port_idx * GPIO_EXT_PORT_SIZE);
> > +       set = gpio->regs + GPIO_SWPORTA_DR + (port_idx * GPIO_SWPORT_DR_SIZE);
> > +       dirout = gpio->regs + GPIO_SWPORTA_DDR +
> > +               (port_idx * GPIO_SWPORT_DDR_SIZE);
> > +
> > +       err = bgpio_init(&port->bgc, gpio->dev, 4, dat, set, NULL, dirout,
> > +                        NULL, false);
> > +       if (err) {
> > +               dev_err(gpio->dev, "failed to init gpio chip for %s\n",
> > +                       port_np->full_name);
> > +               return err;
> > +       }
> > +
> > +       port->bgc.gc.ngpio = ngpio;
> > +       port->bgc.gc.of_node = port_np;
> > +
> > +       /*
> > +        * Only port A can provide interrupts in all configurations of the IP.
> > +        */
> > +       if (port_idx == 0 &&
> > +           of_property_read_bool(port_np, "interrupt-controller"))
> > +               dwapb_configure_irqs(gpio, port);
> > +
> > +       err = gpiochip_add(&port->bgc.gc);
> > +       if (err)
> > +               dev_err(gpio->dev, "failed to register gpiochip for %s\n",
> > +                       port_np->full_name);
> > +       else
> > +               port->is_registered = true;
> > +
> > +       return err;
> > +}
> > +
> > +static void dwapb_gpio_unregister(struct dwapb_gpio *gpio)
> > +{
> > +       unsigned int m;
> > +
> > +       for (m = 0; m < gpio->nr_ports; ++m)
> > +               if (gpio->ports[m].is_registered)
> > +                       WARN_ON(gpiochip_remove(&gpio->ports[m].bgc.gc));
> > +}
> > +
> > +static int dwapb_gpio_probe(struct platform_device *pdev)
> > +{
> > +       struct resource *res;
> > +       struct dwapb_gpio *gpio;
> > +       struct device_node *np;
> > +       int err;
> > +       unsigned int offs = 0;
> > +
> > +       gpio = devm_kzalloc(&pdev->dev, sizeof(*gpio), GFP_KERNEL);
> > +       if (!gpio)
> > +               return -ENOMEM;
> > +       gpio->dev = &pdev->dev;
> > +
> > +       gpio->nr_ports = of_get_child_count(pdev->dev.of_node);
> > +       if (!gpio->nr_ports) {
> > +               err = -EINVAL;
> > +               goto out_err;
> > +       }
> > +       gpio->ports = devm_kzalloc(&pdev->dev, gpio->nr_ports *
> > +                                  sizeof(*gpio->ports), GFP_KERNEL);
> > +       if (!gpio->ports) {
> > +               err = -ENOMEM;
> > +               goto out_err;
> > +       }
> > +
> > +       res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> > +       gpio->regs = devm_ioremap_resource(&pdev->dev, res);
> > +       if (IS_ERR(gpio->regs)) {
> > +               err = PTR_ERR(gpio->regs);
> > +               goto out_err;
> > +       }
> > +
> > +       for_each_child_of_node(pdev->dev.of_node, np) {
> > +               err = dwapb_gpio_add_port(gpio, np, offs++);
> > +               if (err)
> > +                       goto out_unregister;
> > +       }
> > +       platform_set_drvdata(pdev, gpio);
> > +
> > +       return 0;
> > +
> > +out_unregister:
> > +       dwapb_gpio_unregister(gpio);
> > +       dwapb_irq_teardown(gpio);
> > +
> > +out_err:
> > +       return err;
> > +}
> > +
> > +static int dwapb_gpio_remove(struct platform_device *pdev)
> > +{
> > +       struct dwapb_gpio *gpio = platform_get_drvdata(pdev);
> > +
> > +       dwapb_gpio_unregister(gpio);
> > +       dwapb_irq_teardown(gpio);
> > +
> > +       return 0;
> > +}
> > +
> > +static const struct of_device_id dwapb_of_match[] = {
> > +       { .compatible = "snps,dw-apb-gpio" },
> > +       { /* Sentinel */ }
> > +};
> > +MODULE_DEVICE_TABLE(of, dwapb_of_match);
> > +
> > +static struct platform_driver dwapb_gpio_driver = {
> > +       .driver         = {
> > +               .name   = "gpio-dwapb",
> > +               .owner  = THIS_MODULE,
> > +               .of_match_table = of_match_ptr(dwapb_of_match),
> > +       },
> > +       .probe          = dwapb_gpio_probe,
> > +       .remove         = dwapb_gpio_remove,
> > +};
> > +
> > +module_platform_driver(dwapb_gpio_driver);
> > +
> > +MODULE_LICENSE("GPL");
> > +MODULE_AUTHOR("Jamie Iles");
> > +MODULE_DESCRIPTION("Synopsys DesignWare APB GPIO driver");
> > --
> > 1.7.9.5
> >
> --
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