Re: [patch 2/4] SM501: Add gpiolib support

Andrew Morton
2008-06-24T04:05:31Z

On Sun, 22 Jun 2008 22:12:49 +0100 Ben Dooks <ben-linux@fluff.org> wrote:

> Add support for exporting the GPIOs on the SM501
> via gpiolib.
>
> ...
>
> +struct sm501_gpio_chip {
> + struct gpio_chip gpio;
> + struct sm501_gpio *ourgpio; /* to get back to parent. */
> + void __iomem *regbase;
> +};
> +
> +struct sm501_gpio {
> + struct sm501_gpio_chip low;
> + struct sm501_gpio_chip high;
> + spinlock_t lock;
> +
> + unsigned int registered : 1;
> + void __iomem *regs;
> + struct resource *regs_res;
> +};
> +
>
> ...
>
> +static int __devinit sm501_gpio_register_chip(struct sm501_devdata *sm,
> + struct sm501_gpio *gpio,
> + struct sm501_gpio_chip *chip)
> +{
> + struct sm501_platdata *pdata = sm->platdata;
> + struct gpio_chip *gchip = &chip->gpio;
> + unsigned base = pdata->gpio_base;
> +
> + memcpy(chip, &gpio_chip_template, sizeof(struct gpio_chip));

This memcpy is not particularly readable and the driver will explode if
someone adds a new member to the start of struct sm501_gpio_chip, as
they should be able to do.

Less risky would be:

memcpy(&chip->gpio, &gpio_chip_template, sizeof(struct gpio_chip));

But why not actually be type-correct and do

chip->gpio = gpio_chip_template;

?

> +
> + dev_dbg(sm->dev, "registering gpio block %08llx\n",
> + (unsigned long long)iobase);
> +
> + spin_lock_init(&gpio->lock);
> +
> + gpio->regs_res = request_mem_region(iobase, 0x20, "sm501-gpio");
> + if (gpio->regs_res == NULL) {
> + dev_err(sm->dev, "gpio: failed to request region\n");
> + return -ENXIO;
> + }
> +
> + gpio->regs = ioremap(iobase, 0x20);
> + if (gpio->regs == NULL) {
> + dev_err(sm->dev, "gpio: failed to remap registers\n");
> + ret = -ENXIO;
> + goto err_mapped;
> + }
> +
> + /* Register both our chips. */
> +
> + ret = sm501_gpio_register_chip(sm, gpio, &gpio->low);
> + if (ret) {
> + dev_err(sm->dev, "failed to add low chip\n");
> + goto err_mapped;
> + }
> +
> + ret = sm501_gpio_register_chip(sm, gpio, &gpio->high);
> + if (ret) {
> + dev_err(sm->dev, "failed to add high chip\n");
> + goto err_low_chip;
> + }
> +
> + gpio->registered = 1;
> +
> + return 0;
> +
> + err_low_chip:
> + tmp = gpiochip_remove(&gpio->low.gpio);
> + if (tmp) {
> + dev_err(sm->dev, "cannot remove low chip, cannot tidy up\n");
> + return ret;
> + }
> +
> + err_mapped:
> + release_resource(gpio->regs_res);
> + kfree(gpio->regs_res);
> +
> + return ret;
> +}

I see an ioremap(), but no iounmap() on the error path.

Would it not be better to match request_mem_region() with
release_mem_region(), rather than the lower-level release_reource()?

> +static void sm501_gpio_remove(struct sm501_devdata *sm)
> +{
> + int ret;
> +
> + ret = gpiochip_remove(&sm->gpio.low.gpio);
> + if (ret)
> + dev_err(sm->dev, "cannot remove low chip, cannot tidy up\n");
> +
> + ret = gpiochip_remove(&sm->gpio.high.gpio);
> + if (ret)
> + dev_err(sm->dev, "cannot remove high chip, cannot tidy up\n");
> +}

Did we free all the reources here? I see no other
release_resource/release_mem_region/kfrees in the driver?

> +#else
> +static int sm501_register_gpio(struct sm501_devdata *sm)
> +{
> + return 0;
> +}
> +
> +static void sm501_gpio_remove(struct sm501_devdata *sm)
> +{
> +}

Might be better to give these an explicit inline rather than trusting
gcc to not be silly.

> +#endif
> +
> /* sm501_dbg_regs
> *
> * Debug attribute to attach to parent device to show core registers
> @@ -1059,6 +1249,8 @@ static int sm501_init_dev(struct sm501_d
> sm501_register_usbhost(sm, &mem_avail);
> if (idata->devices & (SM501_USE_UART0 | SM501_USE_UART1))
> sm501_register_uart(sm, idata->devices);
> + if (idata->devices & SM501_USE_GPIO)
> + sm501_register_gpio(sm);
> }
>
> ret = sm501_check_clocks(sm);
> @@ -1366,6 +1558,9 @@ static void sm501_dev_remove(struct sm50
> sm501_remove_sub(sm, smdev);
>
> device_remove_file(sm->dev, &dev_attr_dbg_regs);
> +
> + if (sm->gpio.registered)
> + sm501_gpio_remove(sm);
> }
>
> static void sm501_pci_remove(struct pci_dev *dev)
> Index: linux-2.6.26-rc5-quilt1/drivers/mfd/Kconfig
> ===================================================================
> --- linux-2.6.26-rc5-quilt1.orig/drivers/mfd/Kconfig 2008-06-11 11:29:37.000000000 +0100
> +++ linux-2.6.26-rc5-quilt1/drivers/mfd/Kconfig 2008-06-11 11:31:57.000000000 +0100
> @@ -15,6 +15,14 @@ config MFD_SM501
> interface. The device may be connected by PCI or local bus with
> varying functions enabled.
>
> +config MFD_SM501_GPIO
> + bool "Export GPIO via GPIO layer"
> + depends on MFD_SM501 && HAVE_GPIO_LIB
> + ---help---
> + This option uses the gpio library layer to export the 64 GPIO
> + lines on the SM501. The platform data is used to supply the
> + base number for the first GPIO line to register.
> +
> config MFD_ASIC3
> bool "Support for Compaq ASIC3"
> depends on GENERIC_HARDIRQS && ARM