On 11/20/2010 04:55 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>
> ---
> +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_chip *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);
This looks wrong. gpio is of type ti_ssp_gpio_chip, but the ssp core
functions, ssp_read, etc, use dev_to_ssp:
static inline struct ti_ssp *dev_to_ssp(struct device *dev)
{
return dev_get_drvdata(dev->parent);
}
If I understand correctly, the ssp core can only be used to for one
peripheral at a time. Currently the code will allow you to install
several peripherals at once, which will lead to odd behaviour at
runtime. Maybe a better approach would be to have something like this in
drivers/mfd/ti-ssp.c:
struct ti_ssp {
struct resource *res;
struct device *dev;
void __iomem *regs;
struct clk *clk;
int irq;
wait_queue_head_t wqh;
int in_use;
};
static struct ti_ssp ti_ssp = {
.in_use = 0,
};
static DEFINE_SPINLOCK(ti_ssp_lock);
struct ti_ssp *ti_ssp_get(void)
{
spin_lock(&ti_ssp_lock);
if (ti_ssp.in_use) {
spin_unlock(&ti_ssp_lock);
return NULL;
}
ti_ssp.in_use = 1;
spin_unlock(&ti_ssp_lock);
return &ti_ssp;
}
int ti_ssp_put(void)
{
spin_lock(&ti_ssp_lock);
if (!ti_ssp.in_use) {
spin_unlock(&ti_ssp_lock);
return -ENODEV;
}
ti_ssp.in_use = 0;
spin_unlock(&ti_ssp_lock);
return 0;
}
This way, the ssp core api functions can take struct ti_ssp * as their
first argument (which can still be an opaque pointer) and the code
protects against multiple peripherals attempting to register the ssp core.
~Ryan
--
Bluewater Systems Ltd - ARM Technology Solution Centre
Ryan Mallon 5 Amuri Park, 404 Barbadoes St
r...@bluewatersys.com PO Box 13 889, Christchurch 8013
http://www.bluewatersys.com New Zealand
Phone: +64 3 3779127 Freecall: Australia 1800 148 751
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