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[v2,1/2] GPIO: fxl6408: Add support for FXL6408 GPIO expander

Message ID 20210828132316.v2.1.ce74fbdbdc@changeid
State Changes Requested
Delegated to: Stefano Babic
Headers show
Series Add support of the FXL6408 GPIO expander | expand

Commit Message

Oleksandr Suvorov Aug. 28, 2021, 10:23 a.m. UTC
From: Oleksandr Suvorov <oleksandr.suvorov@toradex.com>

Initial support for Fairchild's 8 bit I2C gpio expander FXL6408.
The CONFIG_FXL6408_GPIO define enables support for such devices.

Based on: https://patchwork.kernel.org/patch/9148419/

Signed-off-by: Oleksandr Suvorov <oleksandr.suvorov@toradex.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Oleksandr Suvorov <oleksandr.suvorov@foundries.io>
---

Changes in v2: None

 drivers/gpio/Kconfig        |   7 +
 drivers/gpio/Makefile       |   1 +
 drivers/gpio/gpio-fxl6408.c | 366 ++++++++++++++++++++++++++++++++++++
 3 files changed, 374 insertions(+)
 create mode 100644 drivers/gpio/gpio-fxl6408.c

Comments

Marcel Ziswiler Sept. 9, 2021, 1:29 p.m. UTC | #1
Hi Oleksandr

Just one tiny nit-pick. Otherwise looks good and works great. Thanks!

On Sat, 2021-08-28 at 13:23 +0300, Oleksandr Suvorov wrote:
> From: Oleksandr Suvorov <oleksandr.suvorov@toradex.com>
> 
> Initial support for Fairchild's 8 bit I2C gpio expander FXL6408.
> The CONFIG_FXL6408_GPIO define enables support for such devices.
> 
> Based on: https://patchwork.kernel.org/patch/9148419/
> 
> Signed-off-by: Oleksandr Suvorov <oleksandr.suvorov@toradex.com>

Hehe.

> Reviewed-by: Simon Glass <sjg@chromium.org>
> Signed-off-by: Oleksandr Suvorov <oleksandr.suvorov@foundries.io>

Tested-by: Marcel Ziswiler <marcel.ziswiler@toradex.com>

> ---
> 
> Changes in v2: None
> 
>  drivers/gpio/Kconfig        |   7 +
>  drivers/gpio/Makefile       |   1 +
>  drivers/gpio/gpio-fxl6408.c | 366 ++++++++++++++++++++++++++++++++++++
>  3 files changed, 374 insertions(+)
>  create mode 100644 drivers/gpio/gpio-fxl6408.c
> 
> diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
> index 4a89c1a62b..f56e4cc261 100644
> --- a/drivers/gpio/Kconfig
> +++ b/drivers/gpio/Kconfig
> @@ -123,6 +123,13 @@ config DA8XX_GPIO
>         help
>           This driver supports the DA8xx GPIO controller
>  
> +config FXL6408_GPIO
> +       bool "FXL6408 I2C GPIO expander driver"
> +       depends on DM_GPIO && DM_I2C
> +       help
> +         This driver supports the Fairchild FXL6408 device. FXL6408 is a
> +         fully configurable 8-bit I2C-controlled GPIO expander.
> +
>  config INTEL_BROADWELL_GPIO
>         bool "Intel Broadwell GPIO driver"
>         depends on DM
> diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
> index 58f4704f6b..83d8b5c9d8 100644
> --- a/drivers/gpio/Makefile
> +++ b/drivers/gpio/Makefile
> @@ -16,6 +16,7 @@ obj-$(CONFIG_AT91_GPIO)       += at91_gpio.o
>  obj-$(CONFIG_ATMEL_PIO4)       += atmel_pio4.o
>  obj-$(CONFIG_BCM6345_GPIO)     += bcm6345_gpio.o
>  obj-$(CONFIG_CORTINA_GPIO)      += cortina_gpio.o
> +obj-$(CONFIG_FXL6408_GPIO)     += gpio-fxl6408.o
>  obj-$(CONFIG_INTEL_GPIO)       += intel_gpio.o
>  obj-$(CONFIG_INTEL_ICH6_GPIO)  += intel_ich6_gpio.o
>  obj-$(CONFIG_INTEL_BROADWELL_GPIO)     += intel_broadwell_gpio.o
> diff --git a/drivers/gpio/gpio-fxl6408.c b/drivers/gpio/gpio-fxl6408.c
> new file mode 100644
> index 0000000000..8a86f32365
> --- /dev/null
> +++ b/drivers/gpio/gpio-fxl6408.c
> @@ -0,0 +1,366 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + *  Copyright (C) 2021 Toradex
> + *  Copyright (C) 2016 Broadcom
> + */
> +
> +/**
> + * DOC: FXL6408 I2C to GPIO expander.
> + *
> + * This chip has 8 GPIO lines out of it, and is controlled by an I2C
> + * bus (a pair of lines), providing 4x expansion of GPIO lines. It
> + * also provides an interrupt line out for notifying of state changes.
> + *
> + * Any preconfigured state will be left in place until the GPIO lines
> + * get activated. At power on, everything is treated as an input,
> + * default input is HIGH and pulled-up, all interrupts are masked.
> + *
> + * Documentation can be found at:
> + * https://www.fairchildsemi.com/datasheets/FX/FXL6408.pdf
> + *
> + * This driver bases on:
> + * - the original driver by Eric Anholt <eric@anholt.net>:
> + *   https://patchwork.kernel.org/patch/9148419/
> + * - the Toradex version by Max Krummenacher <max.krummenacher@toradex.com>:
> + *   http://git.toradex.com/cgit/linux-toradex.git/tree/drivers/gpio/gpio-fxl6408.c?h=toradex_5.4-2.3.x-imx
> + * - the U-boot PCA953x driver by Peng Fan <van.freenix@gmail.com>:
> + *   drivers/gpio/pca953x_gpio.c
> + *
> + * TODO:
> + *   - Add interrupts support
> + *   - Replace deprecated callbacks direction_input/output() with set_flags()
> + */
> +
> +#include <common.h>
> +#include <dm.h>
> +#include <dm/device_compat.h>
> +#include <i2c.h>
> +#include <log.h>
> +#include <asm-generic/gpio.h>
> +#include <asm/global_data.h>
> +#include <linux/bitops.h>
> +#include <dt-bindings/gpio/gpio.h>
> +
> +#define REG_DEVID_CTRL         0x01
> +# define SW_RST                        BIT(0)
> +# define RST_INT               BIT(1)
> +/* 0b101 is the Manufacturer's ID assigned to Fairchild by Nokia */
> +# define MF_ID_FAIRCHILD       5
> +
> +/* Bits set here indicate that the GPIO is an output */
> +#define REG_IO_DIR             0x03
> +
> +/*
> + * Bits set here, when the corresponding bit of REG_IO_DIR is set, drive
> + * the output high instead of low.
> + */
> +#define REG_OUT_STATE          0x05
> +
> +/* Bits here make the output High-Z, instead of the OUTPUT value */
> +#define REG_OUT_HIGH_Z         0x07
> +
> +/*
> + * Bits here define the expected input state of the GPIO.
> + * INTERRUPT_STATUS bits will be set when the INPUT transitions away
> + * from this value.
> + */
> +#define REG_IN_DEFAULT_STATE   0x09
> +
> +/*
> + * Bits here enable either pull up or pull down according to
> + * REG_PULL_MODE.
> + */
> +#define REG_PULL_ENABLE                0x0b
> +
> +/*
> + * Bits set here selects a pull-up/pull-down state of pin, which
> + * is configured as Input and the corresponding REG_PULL_ENABLE bit is
> + * set.
> + */
> +#define REG_PULL_MODE          0x0d
> +
> +/* Returns the current status (1 = HIGH) of the input pins */
> +#define REG_IN_STATUS          0x0f
> +
> +/* Mask of pins which can generate interrupts */
> +#define REG_INT_MASK           0x11
> +
> +/* Mask of pins which have generated an interrupt. Cleared on read */
> +#define REG_INT_STATUS         0x13
> +
> +/* Manufacturer's ID getting from Device ID & Ctrl register */
> +enum {
> +       MF_ID_MASK = GENMASK(7, 5),
> +       MF_ID_SHIFT = 5,
> +};
> +
> +/* Firmware revision getting from Device ID & Ctrl register */
> +enum {
> +       FW_REV_MASK = GENMASK(4, 2),
> +       FW_REV_SHIFT = 2,
> +};
> +
> +enum io_direction {
> +       DIR_IN,
> +       DIR_OUT,
> +};
> +
> +/*
> + * struct fxl6408_info - Data for fxl6408
> + *
> + * @dev: udevice structure for the device
> + * @addr: i2c slave address
> + * @reg_io_dir: hold the value of direction register
> + * @reg_output: hold the value of output register
> + */
> +struct fxl6408_info {
> +       struct udevice *dev;
> +       int addr;
> +       u8 device_id;
> +       u8 reg_io_dir;
> +       u8 reg_output;
> +};
> +
> +static inline int fxl6408_write(struct udevice *dev, int reg, u8 val)
> +{
> +       return dm_i2c_write(dev, reg, &val, 1);
> +}
> +
> +static int fxl6408_read(struct udevice *dev, int reg)
> +{
> +       int ret;
> +       u8 tmp;
> +
> +       ret = dm_i2c_read(dev, reg, &tmp, 1);
> +       if (!ret)
> +               ret = tmp;
> +
> +       return ret;
> +}
> +
> +/*
> + * fxl6408_is_output() - check whether the gpio configures as either
> + *                      output or input.
> + * Return: false - input, true - output.
> + */
> +static bool fxl6408_is_output(struct udevice *dev, int offset)
> +{
> +       struct fxl6408_info *info = dev_get_plat(dev);
> +
> +       return info->reg_io_dir & BIT(offset);
> +}
> +
> +static int fxl6408_get_value(struct udevice *dev, uint offset)
> +{
> +       int ret, reg = fxl6408_is_output(dev, offset) ? REG_OUT_STATE : REG_IN_STATUS;
> +
> +       ret = fxl6408_read(dev, reg);
> +       if (ret < 0)
> +               return ret;
> +
> +       return !!(ret & BIT(offset));
> +}
> +
> +static int fxl6408_set_value(struct udevice *dev, uint offset, int value)
> +{
> +       struct fxl6408_info *info = dev_get_plat(dev);
> +       u8 val;
> +       int ret;
> +
> +       if (value)
> +               val = info->reg_output | BIT(offset);
> +       else
> +               val = info->reg_output & ~BIT(offset);
> +
> +       ret = fxl6408_write(dev, REG_OUT_STATE, val);
> +       if (ret < 0)
> +               return ret;
> +
> +       info->reg_output = val;
> +
> +       return 0;
> +}
> +
> +static int fxl6408_set_direction(struct udevice *dev, uint offset,
> +                                enum io_direction dir)
> +{
> +       struct fxl6408_info *info = dev_get_plat(dev);
> +       u8 val;
> +       int ret;
> +
> +       if (dir == DIR_IN)
> +               val = info->reg_io_dir & ~BIT(offset);
> +       else
> +               val = info->reg_io_dir | BIT(offset);
> +
> +       ret = fxl6408_write(dev, REG_IO_DIR, val);
> +       if (ret < 0)
> +               return ret;
> +
> +       info->reg_io_dir = val;
> +
> +       return 0;
> +}
> +
> +static int fxl6408_direction_input(struct udevice *dev, uint offset)
> +{
> +       return fxl6408_set_direction(dev, offset, DIR_IN);
> +}
> +
> +static int fxl6408_direction_output(struct udevice *dev, uint offset, int value)
> +{
> +       int ret;
> +
> +       /* Configure output value */
> +       ret = fxl6408_set_value(dev, offset, value);
> +       if (ret < 0)
> +               return ret;
> +       /* Configure direction as output */
> +       fxl6408_set_direction(dev, offset, DIR_OUT);
> +
> +       return 0;
> +}
> +
> +static int fxl6408_get_function(struct udevice *dev, uint offset)
> +{
> +       if (fxl6408_is_output(dev, offset))
> +               return GPIOF_OUTPUT;
> +       else
> +               return GPIOF_INPUT;
> +}
> +
> +static int fxl6408_xlate(struct udevice *dev, struct gpio_desc *desc,
> +                        struct ofnode_phandle_args *args)
> +{
> +       desc->offset = args->args[0];
> +       desc->flags = args->args[1] & GPIO_ACTIVE_LOW ? GPIOD_ACTIVE_LOW : 0;
> +
> +       return 0;
> +}
> +
> +static const struct dm_gpio_ops fxl6408_ops = {
> +       .direction_input        = fxl6408_direction_input,
> +       .direction_output       = fxl6408_direction_output,
> +       .get_value              = fxl6408_get_value,
> +       .set_value              = fxl6408_set_value,
> +       .get_function           = fxl6408_get_function,
> +       .xlate                  = fxl6408_xlate,
> +};
> +
> +static int fxl6408_probe(struct udevice *dev)
> +{
> +       struct fxl6408_info *info = dev_get_plat(dev);
> +       struct gpio_dev_priv *uc_priv = dev_get_uclass_priv(dev);
> +       char name[32], label[32], *str;
> +       int addr;
> +       int ret;
> +       int size;
> +       const u8 *tmp;
> +       u32 val32;
> +
> +       addr = dev_read_addr(dev);
> +       if (addr == 0)
> +               return -EINVAL;
> +       info->addr = addr;
> +
> +       /*
> +        * Check the device ID register to see if it's responding.
> +        * This also clears RST_INT as a side effect, so we won't get
> +        * the "we've been power cycled" interrupt once interrupts
> +        * being enabled.
> +        */
> +       ret = fxl6408_read(dev, REG_DEVID_CTRL);
> +       if (ret < 0) {
> +               dev_err(dev, "FXL6408 probe returned %d\n", ret);
> +               return ret;
> +       }
> +
> +       if ((ret & MF_ID_MASK) >> MF_ID_SHIFT != MF_ID_FAIRCHILD) {
> +               dev_err(dev, "FXL6408 probe: wrong Manufacturer's ID: 0x%02x\n", ret);
> +               return -ENXIO;
> +       }
> +       info->device_id = ret;
> +
> +       /*
> +        * Disable High-Z of outputs, so that the OUTPUT updates
> +        * actually take effect.
> +        */
> +       ret = fxl6408_write(dev, REG_OUT_HIGH_Z, (u8)0);
> +       if (ret < 0) {
> +               dev_err(dev, "Error writing High-Z register\n");
> +               return ret;
> +       }
> +
> +       /*
> +        * If configured, set initial output state and direction,
> +        * otherwise read them from the chip.
> +        */
> +       if (dev_read_u32(dev, "initial_io_dir", &val32)) {
> +               ret = fxl6408_read(dev, REG_IO_DIR);
> +               if (ret < 0) {
> +                       dev_err(dev, "Error reading direction register\n");
> +                       return ret;
> +               }
> +               info->reg_io_dir = ret;
> +       } else {
> +               info->reg_io_dir = val32 & 0xFF;
> +               ret = fxl6408_write(dev, REG_IO_DIR, info->reg_io_dir);
> +               if (ret < 0) {
> +                       dev_err(dev, "Error setting direction register\n");
> +                       return ret;
> +               }
> +       }
> +
> +       if (dev_read_u32(dev, "initial_output", &val32)) {
> +               ret = fxl6408_read(dev, REG_OUT_STATE);
> +               if (ret < 0) {
> +                       dev_err(dev, "Error reading output register\n");
> +                       return ret;
> +               }
> +               info->reg_output = ret;
> +       } else {
> +               info->reg_output = val32 & 0xFF;
> +               ret = fxl6408_write(dev, REG_OUT_STATE, info->reg_output);
> +               if (ret < 0) {
> +                       dev_err(dev, "Error setting output register\n");
> +                       return ret;
> +               }
> +       }
> +
> +       tmp = dev_read_prop(dev, "label", &size);
> +       if (tmp) {
> +               size = min(size, (int)sizeof(label) - 1);
> +               memcpy(label, tmp, size);
> +               label[size] = '\0';
> +               snprintf(name, sizeof(name), "%s@%x_", label, info->addr);
> +       } else {
> +               snprintf(name, sizeof(name), "gpio@%x_", info->addr);
> +       }
> +
> +       str = strdup(name);
> +       if (!str)
> +               return -ENOMEM;
> +
> +       uc_priv->bank_name = str;
> +       uc_priv->gpio_count = dev_get_driver_data(dev);
> +       uc_priv->gpio_base = -1;
> +
> +       dev_dbg(dev, "%s (FW rev. %ld) is ready\n", str,

That's one l too much in the %ld which my gcc 9.2-2019.12 (arm-9.10)) 9.2.1 20191025 complains as follows:

In file included from drivers/gpio/gpio-fxl6408.c:36:
drivers/gpio/gpio-fxl6408.c: In function ‘fxl6408_probe’:
drivers/gpio/gpio-fxl6408.c:348:15: warning: format ‘%ld’ expects argument of type ‘long int’, but argument 3
has type ‘int’ [-Wformat=]
  348 |  dev_dbg(dev, "%s (FW rev. %ld) is ready\n", str,
      |               ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  349 |   (info->device_id & MF_ID_MASK) >> MF_ID_SHIFT);
      |   ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      |                                  |
      |                                  int
include/dm/device_compat.h:50:10: note: in definition of macro ‘dev_printk_emit’
   50 |   printf(fmt, ##__VA_ARGS__); \
      |          ^~~
include/dm/device_compat.h:117:2: note: in expansion of macro ‘__dev_printk’
  117 |  __dev_printk(LOGL_DEBUG, dev, fmt, ##__VA_ARGS__)
      |  ^~~~~~~~~~~~
drivers/gpio/gpio-fxl6408.c:348:2: note: in expansion of macro ‘dev_dbg’
  348 |  dev_dbg(dev, "%s (FW rev. %ld) is ready\n", str,
      |  ^~~~~~~
drivers/gpio/gpio-fxl6408.c:348:30: note: format string is defined here
  348 |  dev_dbg(dev, "%s (FW rev. %ld) is ready\n", str,
      |                            ~~^
      |                              |
      |                              long int
      |                            %d

> +               (info->device_id & MF_ID_MASK) >> MF_ID_SHIFT);
> +
> +       return 0;
> +}
> +
> +static const struct udevice_id fxl6408_ids[] = {
> +       { .compatible = "fcs,fxl6408", .data = 8 },
> +       { }
> +};
> +
> +U_BOOT_DRIVER(fxl6408_gpio) = {
> +       .name = "fxl6408_gpio",
> +       .id = UCLASS_GPIO,
> +       .ops = &fxl6408_ops,
> +       .probe = fxl6408_probe,
> +       .of_match = fxl6408_ids,
> +       .plat_auto = sizeof(struct fxl6408_info),
> +};

Cheers

Marcel
Oleksandr Suvorov Sept. 9, 2021, 8:14 p.m. UTC | #2
Hi Marcel,

On Thu, Sep 9, 2021 at 4:29 PM Marcel Ziswiler
<marcel.ziswiler@toradex.com> wrote:
>
> Hi Oleksandr
>
> Just one tiny nit-pick. Otherwise looks good and works great. Thanks!

Thanks, I thought I'd already fixed that warning :)
Will be fixed in the next revision.
>
> On Sat, 2021-08-28 at 13:23 +0300, Oleksandr Suvorov wrote:
> > From: Oleksandr Suvorov <oleksandr.suvorov@toradex.com>
> >
> > Initial support for Fairchild's 8 bit I2C gpio expander FXL6408.
> > The CONFIG_FXL6408_GPIO define enables support for such devices.
> >
> > Based on: https://patchwork.kernel.org/patch/9148419/
> >
> > Signed-off-by: Oleksandr Suvorov <oleksandr.suvorov@toradex.com>
>
> Hehe.

Oh, thanks for pointing that out :) I've finished it being in Toradex,
just forgot to resend a fixed version. :)
But as now the patch is changed, probably it's better to refresh the field :)

> > Reviewed-by: Simon Glass <sjg@chromium.org>
> > Signed-off-by: Oleksandr Suvorov <oleksandr.suvorov@foundries.io>
>
> Tested-by: Marcel Ziswiler <marcel.ziswiler@toradex.com>

Thank you!

>
> > ---
> >
> > Changes in v2: None
> >
> >  drivers/gpio/Kconfig        |   7 +
> >  drivers/gpio/Makefile       |   1 +
> >  drivers/gpio/gpio-fxl6408.c | 366 ++++++++++++++++++++++++++++++++++++
> >  3 files changed, 374 insertions(+)
> >  create mode 100644 drivers/gpio/gpio-fxl6408.c
> >
> > diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
> > index 4a89c1a62b..f56e4cc261 100644
> > --- a/drivers/gpio/Kconfig
> > +++ b/drivers/gpio/Kconfig
> > @@ -123,6 +123,13 @@ config DA8XX_GPIO
> >         help
> >           This driver supports the DA8xx GPIO controller
> >
> > +config FXL6408_GPIO
> > +       bool "FXL6408 I2C GPIO expander driver"
> > +       depends on DM_GPIO && DM_I2C
> > +       help
> > +         This driver supports the Fairchild FXL6408 device. FXL6408 is a
> > +         fully configurable 8-bit I2C-controlled GPIO expander.
> > +
> >  config INTEL_BROADWELL_GPIO
> >         bool "Intel Broadwell GPIO driver"
> >         depends on DM
> > diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
> > index 58f4704f6b..83d8b5c9d8 100644
> > --- a/drivers/gpio/Makefile
> > +++ b/drivers/gpio/Makefile
> > @@ -16,6 +16,7 @@ obj-$(CONFIG_AT91_GPIO)       += at91_gpio.o
> >  obj-$(CONFIG_ATMEL_PIO4)       += atmel_pio4.o
> >  obj-$(CONFIG_BCM6345_GPIO)     += bcm6345_gpio.o
> >  obj-$(CONFIG_CORTINA_GPIO)      += cortina_gpio.o
> > +obj-$(CONFIG_FXL6408_GPIO)     += gpio-fxl6408.o
> >  obj-$(CONFIG_INTEL_GPIO)       += intel_gpio.o
> >  obj-$(CONFIG_INTEL_ICH6_GPIO)  += intel_ich6_gpio.o
> >  obj-$(CONFIG_INTEL_BROADWELL_GPIO)     += intel_broadwell_gpio.o
> > diff --git a/drivers/gpio/gpio-fxl6408.c b/drivers/gpio/gpio-fxl6408.c
> > new file mode 100644
> > index 0000000000..8a86f32365
> > --- /dev/null
> > +++ b/drivers/gpio/gpio-fxl6408.c
> > @@ -0,0 +1,366 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + *  Copyright (C) 2021 Toradex
> > + *  Copyright (C) 2016 Broadcom
> > + */
> > +
> > +/**
> > + * DOC: FXL6408 I2C to GPIO expander.
> > + *
> > + * This chip has 8 GPIO lines out of it, and is controlled by an I2C
> > + * bus (a pair of lines), providing 4x expansion of GPIO lines. It
> > + * also provides an interrupt line out for notifying of state changes.
> > + *
> > + * Any preconfigured state will be left in place until the GPIO lines
> > + * get activated. At power on, everything is treated as an input,
> > + * default input is HIGH and pulled-up, all interrupts are masked.
> > + *
> > + * Documentation can be found at:
> > + * https://www.fairchildsemi.com/datasheets/FX/FXL6408.pdf
> > + *
> > + * This driver bases on:
> > + * - the original driver by Eric Anholt <eric@anholt.net>:
> > + *   https://patchwork.kernel.org/patch/9148419/
> > + * - the Toradex version by Max Krummenacher <max.krummenacher@toradex.com>:
> > + *   http://git.toradex.com/cgit/linux-toradex.git/tree/drivers/gpio/gpio-fxl6408.c?h=toradex_5.4-2.3.x-imx
> > + * - the U-boot PCA953x driver by Peng Fan <van.freenix@gmail.com>:
> > + *   drivers/gpio/pca953x_gpio.c
> > + *
> > + * TODO:
> > + *   - Add interrupts support
> > + *   - Replace deprecated callbacks direction_input/output() with set_flags()
> > + */
> > +
> > +#include <common.h>
> > +#include <dm.h>
> > +#include <dm/device_compat.h>
> > +#include <i2c.h>
> > +#include <log.h>
> > +#include <asm-generic/gpio.h>
> > +#include <asm/global_data.h>
> > +#include <linux/bitops.h>
> > +#include <dt-bindings/gpio/gpio.h>
> > +
> > +#define REG_DEVID_CTRL         0x01
> > +# define SW_RST                        BIT(0)
> > +# define RST_INT               BIT(1)
> > +/* 0b101 is the Manufacturer's ID assigned to Fairchild by Nokia */
> > +# define MF_ID_FAIRCHILD       5
> > +
> > +/* Bits set here indicate that the GPIO is an output */
> > +#define REG_IO_DIR             0x03
> > +
> > +/*
> > + * Bits set here, when the corresponding bit of REG_IO_DIR is set, drive
> > + * the output high instead of low.
> > + */
> > +#define REG_OUT_STATE          0x05
> > +
> > +/* Bits here make the output High-Z, instead of the OUTPUT value */
> > +#define REG_OUT_HIGH_Z         0x07
> > +
> > +/*
> > + * Bits here define the expected input state of the GPIO.
> > + * INTERRUPT_STATUS bits will be set when the INPUT transitions away
> > + * from this value.
> > + */
> > +#define REG_IN_DEFAULT_STATE   0x09
> > +
> > +/*
> > + * Bits here enable either pull up or pull down according to
> > + * REG_PULL_MODE.
> > + */
> > +#define REG_PULL_ENABLE                0x0b
> > +
> > +/*
> > + * Bits set here selects a pull-up/pull-down state of pin, which
> > + * is configured as Input and the corresponding REG_PULL_ENABLE bit is
> > + * set.
> > + */
> > +#define REG_PULL_MODE          0x0d
> > +
> > +/* Returns the current status (1 = HIGH) of the input pins */
> > +#define REG_IN_STATUS          0x0f
> > +
> > +/* Mask of pins which can generate interrupts */
> > +#define REG_INT_MASK           0x11
> > +
> > +/* Mask of pins which have generated an interrupt. Cleared on read */
> > +#define REG_INT_STATUS         0x13
> > +
> > +/* Manufacturer's ID getting from Device ID & Ctrl register */
> > +enum {
> > +       MF_ID_MASK = GENMASK(7, 5),
> > +       MF_ID_SHIFT = 5,
> > +};
> > +
> > +/* Firmware revision getting from Device ID & Ctrl register */
> > +enum {
> > +       FW_REV_MASK = GENMASK(4, 2),
> > +       FW_REV_SHIFT = 2,
> > +};
> > +
> > +enum io_direction {
> > +       DIR_IN,
> > +       DIR_OUT,
> > +};
> > +
> > +/*
> > + * struct fxl6408_info - Data for fxl6408
> > + *
> > + * @dev: udevice structure for the device
> > + * @addr: i2c slave address
> > + * @reg_io_dir: hold the value of direction register
> > + * @reg_output: hold the value of output register
> > + */
> > +struct fxl6408_info {
> > +       struct udevice *dev;
> > +       int addr;
> > +       u8 device_id;
> > +       u8 reg_io_dir;
> > +       u8 reg_output;
> > +};
> > +
> > +static inline int fxl6408_write(struct udevice *dev, int reg, u8 val)
> > +{
> > +       return dm_i2c_write(dev, reg, &val, 1);
> > +}
> > +
> > +static int fxl6408_read(struct udevice *dev, int reg)
> > +{
> > +       int ret;
> > +       u8 tmp;
> > +
> > +       ret = dm_i2c_read(dev, reg, &tmp, 1);
> > +       if (!ret)
> > +               ret = tmp;
> > +
> > +       return ret;
> > +}
> > +
> > +/*
> > + * fxl6408_is_output() - check whether the gpio configures as either
> > + *                      output or input.
> > + * Return: false - input, true - output.
> > + */
> > +static bool fxl6408_is_output(struct udevice *dev, int offset)
> > +{
> > +       struct fxl6408_info *info = dev_get_plat(dev);
> > +
> > +       return info->reg_io_dir & BIT(offset);
> > +}
> > +
> > +static int fxl6408_get_value(struct udevice *dev, uint offset)
> > +{
> > +       int ret, reg = fxl6408_is_output(dev, offset) ? REG_OUT_STATE : REG_IN_STATUS;
> > +
> > +       ret = fxl6408_read(dev, reg);
> > +       if (ret < 0)
> > +               return ret;
> > +
> > +       return !!(ret & BIT(offset));
> > +}
> > +
> > +static int fxl6408_set_value(struct udevice *dev, uint offset, int value)
> > +{
> > +       struct fxl6408_info *info = dev_get_plat(dev);
> > +       u8 val;
> > +       int ret;
> > +
> > +       if (value)
> > +               val = info->reg_output | BIT(offset);
> > +       else
> > +               val = info->reg_output & ~BIT(offset);
> > +
> > +       ret = fxl6408_write(dev, REG_OUT_STATE, val);
> > +       if (ret < 0)
> > +               return ret;
> > +
> > +       info->reg_output = val;
> > +
> > +       return 0;
> > +}
> > +
> > +static int fxl6408_set_direction(struct udevice *dev, uint offset,
> > +                                enum io_direction dir)
> > +{
> > +       struct fxl6408_info *info = dev_get_plat(dev);
> > +       u8 val;
> > +       int ret;
> > +
> > +       if (dir == DIR_IN)
> > +               val = info->reg_io_dir & ~BIT(offset);
> > +       else
> > +               val = info->reg_io_dir | BIT(offset);
> > +
> > +       ret = fxl6408_write(dev, REG_IO_DIR, val);
> > +       if (ret < 0)
> > +               return ret;
> > +
> > +       info->reg_io_dir = val;
> > +
> > +       return 0;
> > +}
> > +
> > +static int fxl6408_direction_input(struct udevice *dev, uint offset)
> > +{
> > +       return fxl6408_set_direction(dev, offset, DIR_IN);
> > +}
> > +
> > +static int fxl6408_direction_output(struct udevice *dev, uint offset, int value)
> > +{
> > +       int ret;
> > +
> > +       /* Configure output value */
> > +       ret = fxl6408_set_value(dev, offset, value);
> > +       if (ret < 0)
> > +               return ret;
> > +       /* Configure direction as output */
> > +       fxl6408_set_direction(dev, offset, DIR_OUT);
> > +
> > +       return 0;
> > +}
> > +
> > +static int fxl6408_get_function(struct udevice *dev, uint offset)
> > +{
> > +       if (fxl6408_is_output(dev, offset))
> > +               return GPIOF_OUTPUT;
> > +       else
> > +               return GPIOF_INPUT;
> > +}
> > +
> > +static int fxl6408_xlate(struct udevice *dev, struct gpio_desc *desc,
> > +                        struct ofnode_phandle_args *args)
> > +{
> > +       desc->offset = args->args[0];
> > +       desc->flags = args->args[1] & GPIO_ACTIVE_LOW ? GPIOD_ACTIVE_LOW : 0;
> > +
> > +       return 0;
> > +}
> > +
> > +static const struct dm_gpio_ops fxl6408_ops = {
> > +       .direction_input        = fxl6408_direction_input,
> > +       .direction_output       = fxl6408_direction_output,
> > +       .get_value              = fxl6408_get_value,
> > +       .set_value              = fxl6408_set_value,
> > +       .get_function           = fxl6408_get_function,
> > +       .xlate                  = fxl6408_xlate,
> > +};
> > +
> > +static int fxl6408_probe(struct udevice *dev)
> > +{
> > +       struct fxl6408_info *info = dev_get_plat(dev);
> > +       struct gpio_dev_priv *uc_priv = dev_get_uclass_priv(dev);
> > +       char name[32], label[32], *str;
> > +       int addr;
> > +       int ret;
> > +       int size;
> > +       const u8 *tmp;
> > +       u32 val32;
> > +
> > +       addr = dev_read_addr(dev);
> > +       if (addr == 0)
> > +               return -EINVAL;
> > +       info->addr = addr;
> > +
> > +       /*
> > +        * Check the device ID register to see if it's responding.
> > +        * This also clears RST_INT as a side effect, so we won't get
> > +        * the "we've been power cycled" interrupt once interrupts
> > +        * being enabled.
> > +        */
> > +       ret = fxl6408_read(dev, REG_DEVID_CTRL);
> > +       if (ret < 0) {
> > +               dev_err(dev, "FXL6408 probe returned %d\n", ret);
> > +               return ret;
> > +       }
> > +
> > +       if ((ret & MF_ID_MASK) >> MF_ID_SHIFT != MF_ID_FAIRCHILD) {
> > +               dev_err(dev, "FXL6408 probe: wrong Manufacturer's ID: 0x%02x\n", ret);
> > +               return -ENXIO;
> > +       }
> > +       info->device_id = ret;
> > +
> > +       /*
> > +        * Disable High-Z of outputs, so that the OUTPUT updates
> > +        * actually take effect.
> > +        */
> > +       ret = fxl6408_write(dev, REG_OUT_HIGH_Z, (u8)0);
> > +       if (ret < 0) {
> > +               dev_err(dev, "Error writing High-Z register\n");
> > +               return ret;
> > +       }
> > +
> > +       /*
> > +        * If configured, set initial output state and direction,
> > +        * otherwise read them from the chip.
> > +        */
> > +       if (dev_read_u32(dev, "initial_io_dir", &val32)) {
> > +               ret = fxl6408_read(dev, REG_IO_DIR);
> > +               if (ret < 0) {
> > +                       dev_err(dev, "Error reading direction register\n");
> > +                       return ret;
> > +               }
> > +               info->reg_io_dir = ret;
> > +       } else {
> > +               info->reg_io_dir = val32 & 0xFF;
> > +               ret = fxl6408_write(dev, REG_IO_DIR, info->reg_io_dir);
> > +               if (ret < 0) {
> > +                       dev_err(dev, "Error setting direction register\n");
> > +                       return ret;
> > +               }
> > +       }
> > +
> > +       if (dev_read_u32(dev, "initial_output", &val32)) {
> > +               ret = fxl6408_read(dev, REG_OUT_STATE);
> > +               if (ret < 0) {
> > +                       dev_err(dev, "Error reading output register\n");
> > +                       return ret;
> > +               }
> > +               info->reg_output = ret;
> > +       } else {
> > +               info->reg_output = val32 & 0xFF;
> > +               ret = fxl6408_write(dev, REG_OUT_STATE, info->reg_output);
> > +               if (ret < 0) {
> > +                       dev_err(dev, "Error setting output register\n");
> > +                       return ret;
> > +               }
> > +       }
> > +
> > +       tmp = dev_read_prop(dev, "label", &size);
> > +       if (tmp) {
> > +               size = min(size, (int)sizeof(label) - 1);
> > +               memcpy(label, tmp, size);
> > +               label[size] = '\0';
> > +               snprintf(name, sizeof(name), "%s@%x_", label, info->addr);
> > +       } else {
> > +               snprintf(name, sizeof(name), "gpio@%x_", info->addr);
> > +       }
> > +
> > +       str = strdup(name);
> > +       if (!str)
> > +               return -ENOMEM;
> > +
> > +       uc_priv->bank_name = str;
> > +       uc_priv->gpio_count = dev_get_driver_data(dev);
> > +       uc_priv->gpio_base = -1;
> > +
> > +       dev_dbg(dev, "%s (FW rev. %ld) is ready\n", str,
>
> That's one l too much in the %ld which my gcc 9.2-2019.12 (arm-9.10)) 9.2.1 20191025 complains as follows:
>
> In file included from drivers/gpio/gpio-fxl6408.c:36:
> drivers/gpio/gpio-fxl6408.c: In function ‘fxl6408_probe’:
> drivers/gpio/gpio-fxl6408.c:348:15: warning: format ‘%ld’ expects argument of type ‘long int’, but argument 3
> has type ‘int’ [-Wformat=]
>   348 |  dev_dbg(dev, "%s (FW rev. %ld) is ready\n", str,
>       |               ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>   349 |   (info->device_id & MF_ID_MASK) >> MF_ID_SHIFT);
>       |   ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>       |                                  |
>       |                                  int
> include/dm/device_compat.h:50:10: note: in definition of macro ‘dev_printk_emit’
>    50 |   printf(fmt, ##__VA_ARGS__); \
>       |          ^~~
> include/dm/device_compat.h:117:2: note: in expansion of macro ‘__dev_printk’
>   117 |  __dev_printk(LOGL_DEBUG, dev, fmt, ##__VA_ARGS__)
>       |  ^~~~~~~~~~~~
> drivers/gpio/gpio-fxl6408.c:348:2: note: in expansion of macro ‘dev_dbg’
>   348 |  dev_dbg(dev, "%s (FW rev. %ld) is ready\n", str,
>       |  ^~~~~~~
> drivers/gpio/gpio-fxl6408.c:348:30: note: format string is defined here
>   348 |  dev_dbg(dev, "%s (FW rev. %ld) is ready\n", str,
>       |                            ~~^
>       |                              |
>       |                              long int
>       |                            %d
>
> > +               (info->device_id & MF_ID_MASK) >> MF_ID_SHIFT);
> > +
> > +       return 0;
> > +}
> > +
> > +static const struct udevice_id fxl6408_ids[] = {
> > +       { .compatible = "fcs,fxl6408", .data = 8 },
> > +       { }
> > +};
> > +
> > +U_BOOT_DRIVER(fxl6408_gpio) = {
> > +       .name = "fxl6408_gpio",
> > +       .id = UCLASS_GPIO,
> > +       .ops = &fxl6408_ops,
> > +       .probe = fxl6408_probe,
> > +       .of_match = fxl6408_ids,
> > +       .plat_auto = sizeof(struct fxl6408_info),
> > +};
>
> Cheers
>
> Marcel
diff mbox series

Patch

diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index 4a89c1a62b..f56e4cc261 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -123,6 +123,13 @@  config DA8XX_GPIO
 	help
 	  This driver supports the DA8xx GPIO controller
 
+config FXL6408_GPIO
+	bool "FXL6408 I2C GPIO expander driver"
+	depends on DM_GPIO && DM_I2C
+	help
+	  This driver supports the Fairchild FXL6408 device. FXL6408 is a
+	  fully configurable 8-bit I2C-controlled GPIO expander.
+
 config INTEL_BROADWELL_GPIO
 	bool "Intel Broadwell GPIO driver"
 	depends on DM
diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
index 58f4704f6b..83d8b5c9d8 100644
--- a/drivers/gpio/Makefile
+++ b/drivers/gpio/Makefile
@@ -16,6 +16,7 @@  obj-$(CONFIG_AT91_GPIO)	+= at91_gpio.o
 obj-$(CONFIG_ATMEL_PIO4)	+= atmel_pio4.o
 obj-$(CONFIG_BCM6345_GPIO)	+= bcm6345_gpio.o
 obj-$(CONFIG_CORTINA_GPIO)      += cortina_gpio.o
+obj-$(CONFIG_FXL6408_GPIO)	+= gpio-fxl6408.o
 obj-$(CONFIG_INTEL_GPIO)	+= intel_gpio.o
 obj-$(CONFIG_INTEL_ICH6_GPIO)	+= intel_ich6_gpio.o
 obj-$(CONFIG_INTEL_BROADWELL_GPIO)	+= intel_broadwell_gpio.o
diff --git a/drivers/gpio/gpio-fxl6408.c b/drivers/gpio/gpio-fxl6408.c
new file mode 100644
index 0000000000..8a86f32365
--- /dev/null
+++ b/drivers/gpio/gpio-fxl6408.c
@@ -0,0 +1,366 @@ 
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *  Copyright (C) 2021 Toradex
+ *  Copyright (C) 2016 Broadcom
+ */
+
+/**
+ * DOC: FXL6408 I2C to GPIO expander.
+ *
+ * This chip has 8 GPIO lines out of it, and is controlled by an I2C
+ * bus (a pair of lines), providing 4x expansion of GPIO lines. It
+ * also provides an interrupt line out for notifying of state changes.
+ *
+ * Any preconfigured state will be left in place until the GPIO lines
+ * get activated. At power on, everything is treated as an input,
+ * default input is HIGH and pulled-up, all interrupts are masked.
+ *
+ * Documentation can be found at:
+ * https://www.fairchildsemi.com/datasheets/FX/FXL6408.pdf
+ *
+ * This driver bases on:
+ * - the original driver by Eric Anholt <eric@anholt.net>:
+ *   https://patchwork.kernel.org/patch/9148419/
+ * - the Toradex version by Max Krummenacher <max.krummenacher@toradex.com>:
+ *   http://git.toradex.com/cgit/linux-toradex.git/tree/drivers/gpio/gpio-fxl6408.c?h=toradex_5.4-2.3.x-imx
+ * - the U-boot PCA953x driver by Peng Fan <van.freenix@gmail.com>:
+ *   drivers/gpio/pca953x_gpio.c
+ *
+ * TODO:
+ *   - Add interrupts support
+ *   - Replace deprecated callbacks direction_input/output() with set_flags()
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <dm/device_compat.h>
+#include <i2c.h>
+#include <log.h>
+#include <asm-generic/gpio.h>
+#include <asm/global_data.h>
+#include <linux/bitops.h>
+#include <dt-bindings/gpio/gpio.h>
+
+#define REG_DEVID_CTRL		0x01
+# define SW_RST			BIT(0)
+# define RST_INT		BIT(1)
+/* 0b101 is the Manufacturer's ID assigned to Fairchild by Nokia */
+# define MF_ID_FAIRCHILD	5
+
+/* Bits set here indicate that the GPIO is an output */
+#define REG_IO_DIR		0x03
+
+/*
+ * Bits set here, when the corresponding bit of REG_IO_DIR is set, drive
+ * the output high instead of low.
+ */
+#define REG_OUT_STATE		0x05
+
+/* Bits here make the output High-Z, instead of the OUTPUT value */
+#define REG_OUT_HIGH_Z		0x07
+
+/*
+ * Bits here define the expected input state of the GPIO.
+ * INTERRUPT_STATUS bits will be set when the INPUT transitions away
+ * from this value.
+ */
+#define REG_IN_DEFAULT_STATE	0x09
+
+/*
+ * Bits here enable either pull up or pull down according to
+ * REG_PULL_MODE.
+ */
+#define REG_PULL_ENABLE		0x0b
+
+/*
+ * Bits set here selects a pull-up/pull-down state of pin, which
+ * is configured as Input and the corresponding REG_PULL_ENABLE bit is
+ * set.
+ */
+#define REG_PULL_MODE		0x0d
+
+/* Returns the current status (1 = HIGH) of the input pins */
+#define REG_IN_STATUS		0x0f
+
+/* Mask of pins which can generate interrupts */
+#define REG_INT_MASK		0x11
+
+/* Mask of pins which have generated an interrupt. Cleared on read */
+#define REG_INT_STATUS		0x13
+
+/* Manufacturer's ID getting from Device ID & Ctrl register */
+enum {
+	MF_ID_MASK = GENMASK(7, 5),
+	MF_ID_SHIFT = 5,
+};
+
+/* Firmware revision getting from Device ID & Ctrl register */
+enum {
+	FW_REV_MASK = GENMASK(4, 2),
+	FW_REV_SHIFT = 2,
+};
+
+enum io_direction {
+	DIR_IN,
+	DIR_OUT,
+};
+
+/*
+ * struct fxl6408_info - Data for fxl6408
+ *
+ * @dev: udevice structure for the device
+ * @addr: i2c slave address
+ * @reg_io_dir: hold the value of direction register
+ * @reg_output: hold the value of output register
+ */
+struct fxl6408_info {
+	struct udevice *dev;
+	int addr;
+	u8 device_id;
+	u8 reg_io_dir;
+	u8 reg_output;
+};
+
+static inline int fxl6408_write(struct udevice *dev, int reg, u8 val)
+{
+	return dm_i2c_write(dev, reg, &val, 1);
+}
+
+static int fxl6408_read(struct udevice *dev, int reg)
+{
+	int ret;
+	u8 tmp;
+
+	ret = dm_i2c_read(dev, reg, &tmp, 1);
+	if (!ret)
+		ret = tmp;
+
+	return ret;
+}
+
+/*
+ * fxl6408_is_output() - check whether the gpio configures as either
+ *			 output or input.
+ * Return: false - input, true - output.
+ */
+static bool fxl6408_is_output(struct udevice *dev, int offset)
+{
+	struct fxl6408_info *info = dev_get_plat(dev);
+
+	return info->reg_io_dir & BIT(offset);
+}
+
+static int fxl6408_get_value(struct udevice *dev, uint offset)
+{
+	int ret, reg = fxl6408_is_output(dev, offset) ? REG_OUT_STATE : REG_IN_STATUS;
+
+	ret = fxl6408_read(dev, reg);
+	if (ret < 0)
+		return ret;
+
+	return !!(ret & BIT(offset));
+}
+
+static int fxl6408_set_value(struct udevice *dev, uint offset, int value)
+{
+	struct fxl6408_info *info = dev_get_plat(dev);
+	u8 val;
+	int ret;
+
+	if (value)
+		val = info->reg_output | BIT(offset);
+	else
+		val = info->reg_output & ~BIT(offset);
+
+	ret = fxl6408_write(dev, REG_OUT_STATE, val);
+	if (ret < 0)
+		return ret;
+
+	info->reg_output = val;
+
+	return 0;
+}
+
+static int fxl6408_set_direction(struct udevice *dev, uint offset,
+				 enum io_direction dir)
+{
+	struct fxl6408_info *info = dev_get_plat(dev);
+	u8 val;
+	int ret;
+
+	if (dir == DIR_IN)
+		val = info->reg_io_dir & ~BIT(offset);
+	else
+		val = info->reg_io_dir | BIT(offset);
+
+	ret = fxl6408_write(dev, REG_IO_DIR, val);
+	if (ret < 0)
+		return ret;
+
+	info->reg_io_dir = val;
+
+	return 0;
+}
+
+static int fxl6408_direction_input(struct udevice *dev, uint offset)
+{
+	return fxl6408_set_direction(dev, offset, DIR_IN);
+}
+
+static int fxl6408_direction_output(struct udevice *dev, uint offset, int value)
+{
+	int ret;
+
+	/* Configure output value */
+	ret = fxl6408_set_value(dev, offset, value);
+	if (ret < 0)
+		return ret;
+	/* Configure direction as output */
+	fxl6408_set_direction(dev, offset, DIR_OUT);
+
+	return 0;
+}
+
+static int fxl6408_get_function(struct udevice *dev, uint offset)
+{
+	if (fxl6408_is_output(dev, offset))
+		return GPIOF_OUTPUT;
+	else
+		return GPIOF_INPUT;
+}
+
+static int fxl6408_xlate(struct udevice *dev, struct gpio_desc *desc,
+			 struct ofnode_phandle_args *args)
+{
+	desc->offset = args->args[0];
+	desc->flags = args->args[1] & GPIO_ACTIVE_LOW ? GPIOD_ACTIVE_LOW : 0;
+
+	return 0;
+}
+
+static const struct dm_gpio_ops fxl6408_ops = {
+	.direction_input        = fxl6408_direction_input,
+	.direction_output       = fxl6408_direction_output,
+	.get_value              = fxl6408_get_value,
+	.set_value              = fxl6408_set_value,
+	.get_function           = fxl6408_get_function,
+	.xlate                  = fxl6408_xlate,
+};
+
+static int fxl6408_probe(struct udevice *dev)
+{
+	struct fxl6408_info *info = dev_get_plat(dev);
+	struct gpio_dev_priv *uc_priv = dev_get_uclass_priv(dev);
+	char name[32], label[32], *str;
+	int addr;
+	int ret;
+	int size;
+	const u8 *tmp;
+	u32 val32;
+
+	addr = dev_read_addr(dev);
+	if (addr == 0)
+		return -EINVAL;
+	info->addr = addr;
+
+	/*
+	 * Check the device ID register to see if it's responding.
+	 * This also clears RST_INT as a side effect, so we won't get
+	 * the "we've been power cycled" interrupt once interrupts
+	 * being enabled.
+	 */
+	ret = fxl6408_read(dev, REG_DEVID_CTRL);
+	if (ret < 0) {
+		dev_err(dev, "FXL6408 probe returned %d\n", ret);
+		return ret;
+	}
+
+	if ((ret & MF_ID_MASK) >> MF_ID_SHIFT != MF_ID_FAIRCHILD) {
+		dev_err(dev, "FXL6408 probe: wrong Manufacturer's ID: 0x%02x\n", ret);
+		return -ENXIO;
+	}
+	info->device_id = ret;
+
+	/*
+	 * Disable High-Z of outputs, so that the OUTPUT updates
+	 * actually take effect.
+	 */
+	ret = fxl6408_write(dev, REG_OUT_HIGH_Z, (u8)0);
+	if (ret < 0) {
+		dev_err(dev, "Error writing High-Z register\n");
+		return ret;
+	}
+
+	/*
+	 * If configured, set initial output state and direction,
+	 * otherwise read them from the chip.
+	 */
+	if (dev_read_u32(dev, "initial_io_dir", &val32)) {
+		ret = fxl6408_read(dev, REG_IO_DIR);
+		if (ret < 0) {
+			dev_err(dev, "Error reading direction register\n");
+			return ret;
+		}
+		info->reg_io_dir = ret;
+	} else {
+		info->reg_io_dir = val32 & 0xFF;
+		ret = fxl6408_write(dev, REG_IO_DIR, info->reg_io_dir);
+		if (ret < 0) {
+			dev_err(dev, "Error setting direction register\n");
+			return ret;
+		}
+	}
+
+	if (dev_read_u32(dev, "initial_output", &val32)) {
+		ret = fxl6408_read(dev, REG_OUT_STATE);
+		if (ret < 0) {
+			dev_err(dev, "Error reading output register\n");
+			return ret;
+		}
+		info->reg_output = ret;
+	} else {
+		info->reg_output = val32 & 0xFF;
+		ret = fxl6408_write(dev, REG_OUT_STATE, info->reg_output);
+		if (ret < 0) {
+			dev_err(dev, "Error setting output register\n");
+			return ret;
+		}
+	}
+
+	tmp = dev_read_prop(dev, "label", &size);
+	if (tmp) {
+		size = min(size, (int)sizeof(label) - 1);
+		memcpy(label, tmp, size);
+		label[size] = '\0';
+		snprintf(name, sizeof(name), "%s@%x_", label, info->addr);
+	} else {
+		snprintf(name, sizeof(name), "gpio@%x_", info->addr);
+	}
+
+	str = strdup(name);
+	if (!str)
+		return -ENOMEM;
+
+	uc_priv->bank_name = str;
+	uc_priv->gpio_count = dev_get_driver_data(dev);
+	uc_priv->gpio_base = -1;
+
+	dev_dbg(dev, "%s (FW rev. %ld) is ready\n", str,
+		(info->device_id & MF_ID_MASK) >> MF_ID_SHIFT);
+
+	return 0;
+}
+
+static const struct udevice_id fxl6408_ids[] = {
+	{ .compatible = "fcs,fxl6408", .data = 8 },
+	{ }
+};
+
+U_BOOT_DRIVER(fxl6408_gpio) = {
+	.name = "fxl6408_gpio",
+	.id = UCLASS_GPIO,
+	.ops = &fxl6408_ops,
+	.probe = fxl6408_probe,
+	.of_match = fxl6408_ids,
+	.plat_auto = sizeof(struct fxl6408_info),
+};