On 11/16/2010 08:12 AM, Cyril Chemparathy wrote:
> TI's SSP controller pins can be directly read and written to behave like a
> GPIO. This patch adds a GPIO driver that exposes such functionality.
>
> Signed-off-by: Cyril Chemparathy <cy...@ti.com>
> ---
> drivers/mfd/Kconfig | 10 ++
> drivers/mfd/Makefile | 1 +
> drivers/mfd/ti-ssp-gpio.c | 205
> ++++++++++++++++++++++++++++++++++++++++++++
> include/linux/mfd/ti_ssp.h | 4 +
> 4 files changed, 220 insertions(+), 0 deletions(-)
> create mode 100644 drivers/mfd/ti-ssp-gpio.c
Should go under drivers/gpio. This is not a multifunction driver.
> +#include <linux/init.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/io.h>
> +#include <linux/err.h>
> +#include <linux/slab.h>
> +#include <linux/gpio.h>
> +#include <linux/platform_device.h>
> +#include <linux/mfd/ti_ssp.h>
> +
> +struct ti_ssp_gpio {
This is a confusing name because it sounds like this struct maps to a
single gpio rather than bank. Perhaps a better name is ti_ssp_gpio_chip?
> + struct gpio_chip chip;
> +#define chip2gpio(chip) container_of(chip, struct ti_ssp_gpio, chip)
Please don't put #define's in the middle of a struct. Move it either
before or after the structure definition. It is also confusingly named,
something like to_ti_ssp_gpio_chip might be better.
> +static int value_get(struct gpio_chip *chip, unsigned gpio_num)
> +{
> + struct ti_ssp_gpio *gpio = chip2gpio(chip);
> + int ret;
> +
> + spin_lock(&gpio->lock);
> +
> + ret = ti_ssp_raw_read(gpio->dev);
> + if (ret >= 0)
> + ret = (ret & BIT(gpio_num)) ? 1 : 0;
ret = !!(ret & BIT(gpio_num));
> +
> + spin_unlock(&gpio->lock);
> + return ret;
> +}
> +static int __devinit ti_ssp_gpio_probe(struct platform_device *pdev)
> +{
> + const struct ti_ssp_gpio_data *pdata = pdev->dev.platform_data;
> + struct device *dev = &pdev->dev;
> + struct ti_ssp_gpio *gpio;
> + int error;
> +
> + if (!pdata) {
> + dev_err(dev, "platform data not found\n");
> + return -EINVAL;
> + }
> +
> + gpio = kzalloc(sizeof(*gpio), GFP_KERNEL);
> + if (!gpio) {
> + dev_err(dev, "cannot allocate driver data\n");
> + return -ENOMEM;
> + }
> +
> + gpio->dev = dev;
> + gpio->iosel = SSP_PIN_SEL(0, SSP_IN) | SSP_PIN_SEL(1, SSP_IN) |
> + SSP_PIN_SEL(2, SSP_IN) | SSP_PIN_SEL(3, SSP_IN);
> + error = ti_ssp_set_iosel(gpio->dev, gpio->iosel);
> + if (error < 0) {
> + dev_err(dev, "gpio io setup failed (%d)\n", error);
> + goto error;
> + }
> +
> + spin_lock_init(&gpio->lock);
> + platform_set_drvdata(pdev, gpio);
> +
> + gpio->chip.base = pdata->start;
> + gpio->chip.ngpio = 4;
Is this always four or can the SSP peripheral be configured to have
varying numbers of gpios. Maybe the number of gpios should be passed via
platform data?
> + gpio->chip.dev = &pdev->dev;
> + gpio->chip.label = "ti_ssp_gpio";
> + gpio->chip.owner = THIS_MODULE;
> + gpio->chip.get = value_get;
> + gpio->chip.set = value_set;
> + gpio->chip.direction_input = direction_in;
> + gpio->chip.direction_output = direction_out;
> +
> + error = gpiochip_add(&gpio->chip);
> + if (error < 0) {
> + dev_err(dev, "gpio chip registration failed (%d)\n", error);
> + goto error;
> + }
> +
> + dev_info(dev, "ssp gpio interface registered\n");
> + return 0;
> +
> +error:
> + kfree(gpio);
> + return error;
> +}
~Ryan
--
Bluewater Systems Ltd - ARM Technology Solution Centre
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r...@bluewatersys.com PO Box 13 889, Christchurch 8013
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