Re: [PATCH 1/2] gpio: Add driver for AXM55xx SSP chip selects

[Linus Walleij]

I need an ACK from Mark Brown on this before I apply.
The driver seems to do what it should, but I need Mark to
be OK with exporting the CS signals from an SSP/SPI block
to be exposed to Linux as GPIOs.

(Top-posting and quoting patch verbatim so Mark gets it.)

Yours,
Linus Walleij

On Mon, Sep 1, 2014 at 2:53 PM, Anders Berg <anders.berg@xxxxxxxxxxxxx> wrote:
> The AXM55xx device has a ARM PL022 SSP controller with an extension that
> enables the control of up to five chip select signals. This driver implements
> the logic to control these signals and exports them as GPIOs.
>
> Signed-off-by: Anders Berg <anders.berg@xxxxxxxxxxxxx>
> ---
>  drivers/gpio/Kconfig          |   8 +++
>  drivers/gpio/Makefile         |   1 +
>  drivers/gpio/gpio-axxia-ssp.c | 128 ++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 137 insertions(+)
>  create mode 100644 drivers/gpio/gpio-axxia-ssp.c
>
> diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
> index 9de1515..c2f2686 100644
> --- a/drivers/gpio/Kconfig
> +++ b/drivers/gpio/Kconfig
> @@ -112,6 +112,14 @@ config GPIO_MAX730X
>
>  comment "Memory mapped GPIO drivers:"
>
> +config GPIO_AXXIA_SSP
> +       tristate "AXM55xx SSP chip select pins as GPIO"
> +       depends on ARCH_AXXIA
> +       default y if SPI_MASTER
> +       select GPIO_GENERIC
> +       help
> +         Say yes here to get GPIO interface for AXM55xx SSP chip select signals.
> +
>  config GPIO_CLPS711X
>         tristate "CLPS711X GPIO support"
>         depends on ARCH_CLPS711X || COMPILE_TEST
> diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
> index 5d024e3..01e1869 100644
> --- a/drivers/gpio/Makefile
> +++ b/drivers/gpio/Makefile
> @@ -18,6 +18,7 @@ obj-$(CONFIG_GPIO_ADP5520)    += gpio-adp5520.o
>  obj-$(CONFIG_GPIO_ADP5588)     += gpio-adp5588.o
>  obj-$(CONFIG_GPIO_AMD8111)     += gpio-amd8111.o
>  obj-$(CONFIG_GPIO_ARIZONA)     += gpio-arizona.o
> +obj-$(CONFIG_GPIO_AXXIA_SSP)   += gpio-axxia-ssp.o
>  obj-$(CONFIG_GPIO_BCM_KONA)    += gpio-bcm-kona.o
>  obj-$(CONFIG_GPIO_BT8XX)       += gpio-bt8xx.o
>  obj-$(CONFIG_GPIO_CLPS711X)    += gpio-clps711x.o
> diff --git a/drivers/gpio/gpio-axxia-ssp.c b/drivers/gpio/gpio-axxia-ssp.c
> new file mode 100644
> index 0000000..5884206
> --- /dev/null
> +++ b/drivers/gpio/gpio-axxia-ssp.c
> @@ -0,0 +1,128 @@
> +/*
> + * GPIO interface for SSP chip select outputs.
> + *
> + * Copyright (C) 2013 LSI 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; either version 2 of the License, or
> + * (at your option) any later version.
> + */
> +
> +#include <linux/module.h>
> +#include <linux/bitops.h>
> +#include <linux/init.h>
> +#include <linux/gpio.h>
> +#include <linux/platform_device.h>
> +#include <linux/io.h>
> +#include <linux/of.h>
> +
> +struct gpio_dev {
> +       void __iomem    *reg;
> +       struct gpio_chip gpio_chip;
> +};
> +
> +static int ssp_gpio_direction_out(struct gpio_chip *chip,
> +                                 unsigned offset, int value)
> +{
> +       /* Always outputs */
> +       return 0;
> +}
> +
> +static int ssp_gpio_direction_in(struct gpio_chip *chip, unsigned offset)
> +{
> +       return -ENXIO;
> +}
> +
> +static int ssp_gpio_get(struct gpio_chip *chip, unsigned offset)
> +{
> +       struct gpio_dev *priv = dev_get_drvdata(chip->dev);
> +       u32 tmp;
> +
> +       tmp = readl(priv->reg);
> +       return !!(tmp & BIT(offset));
> +}
> +
> +static void ssp_gpio_set(struct gpio_chip *chip, unsigned offset, int value)
> +{
> +       struct gpio_dev *priv = dev_get_drvdata(chip->dev);
> +       u32 tmp;
> +
> +       tmp = readl(priv->reg);
> +       if (value)
> +               tmp |= BIT(offset);
> +       else
> +               tmp &= ~BIT(offset);
> +       writel(tmp, priv->reg);
> +}
> +
> +static int ssp_gpio_probe(struct platform_device *pdev)
> +{
> +       struct gpio_dev *priv;
> +       struct resource *io;
> +       struct gpio_chip *chip;
> +       int ret;
> +
> +       priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
> +       if (!priv)
> +               return -ENOMEM;
> +
> +       io = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +       priv->reg = devm_ioremap(&pdev->dev, io->start, resource_size(io));
> +       if (!priv->reg)
> +               return -ENXIO;
> +
> +       platform_set_drvdata(pdev, priv);
> +
> +       chip = &priv->gpio_chip;
> +       chip->dev = &pdev->dev;
> +#ifdef CONFIG_OF_GPIO
> +       chip->of_node = pdev->dev.of_node;
> +#endif
> +       chip->direction_input = ssp_gpio_direction_in;
> +       chip->direction_output = ssp_gpio_direction_out;
> +       chip->get = ssp_gpio_get;
> +       chip->set = ssp_gpio_set;
> +       chip->label = "ssp-gpio";
> +       chip->owner = THIS_MODULE;
> +       chip->base = -1;
> +       chip->ngpio = 5;
> +
> +       /* Set all 5 chip-selects high (de-asserted) by default */
> +       writel(0x1f, priv->reg);
> +
> +       ret = gpiochip_add(chip);
> +       if (ret < 0)
> +               dev_err(&pdev->dev, "failed to register chip, %d\n", ret);
> +
> +       return ret;
> +}
> +
> +static int ssp_gpio_remove(struct platform_device *pdev)
> +{
> +       struct gpio_dev *priv = dev_get_drvdata(&pdev->dev);
> +
> +       return gpiochip_remove(&priv->gpio_chip);
> +}
> +
> +static const struct of_device_id ssp_gpio_id_table[] = {
> +       { .compatible = "lsi,ssp-gpio" },
> +       {}
> +};
> +MODULE_DEVICE_TABLE(platform, ssp_gpio_id_table);
> +
> +static struct platform_driver ssp_gpio_driver = {
> +       .driver = {
> +               .name = "ssp-gpio",
> +               .owner = THIS_MODULE,
> +               .of_match_table = ssp_gpio_id_table
> +       },
> +       .probe = ssp_gpio_probe,
> +       .remove = ssp_gpio_remove,
> +};
> +
> +module_platform_driver(ssp_gpio_driver);
> +
> +MODULE_AUTHOR("LSI Corporation");
> +MODULE_DESCRIPTION("GPIO interface for SSP chip selects");
> +MODULE_LICENSE("GPL");
> --
> 1.9.1
>
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