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Date: Thu, 4 Sep 2014 19:04:44 +0200
From: Linus Walleij <linus.walleij@...aro.org>
To: Anders Berg <anders.berg@...gotech.com>,
Mark Brown <broonie@...nel.org>,
"linux-spi@...r.kernel.org" <linux-spi@...r.kernel.org>
Cc: Alexandre Courbot <gnurou@...il.com>,
"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
"linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>,
"linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2] gpio: Add driver for AXM55xx SSP chip selects
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@...gotech.com> 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@...gotech.com>
> ---
> 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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