On Mon, Jan 15, 2018 at 4:13 AM, Jonathan Neuschäfer <j.neuschaefer@xxxxxxx> wrote: > This patch is based on code developed by Albert Herranz and the GameCube > Linux Team, file arch/powerpc/platforms/embedded6xx/hlwd-gpio.c, > available at https://github.com/DeltaResero/GC-Wii-Linux-Kernels, but > has grown quite dissimilar. I'm impressed by this effort. As with all reverse engineering. > This driver currently uses __raw_readl and __raw_writel to access the > GPIO controller's MMIO registers. I wonder if readl/writel plus explicit > byte-swapping would be more correct, because it could be independent of > the CPU's endianness. That said, this hardware only exists in two > big-endian machines (Wii and Wii U). I don't know about PPC but I think you're supposed to use ioread32be() and iowrite32be() to do explicit BE access. But when I look at it, I think you can just use the gpio-mmio library for this driver and cut down code cosiderably. > +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt Can't you just save a pointer to struct device *dev in the state container and use dev_info(state->dev, ...) etc instead of this? > +#include <linux/of_gpio.h> This include should not be needed. > +/* > + * Update the bit with the given bit offset in the given register to a given > + * value > + */ > +static void hlwd_gpio_update_bit(struct gpio_chip *gc, unsigned int reg, > + int offset, int value) > +{ > + struct hlwd_gpio *hlwd = gpiochip_get_data(gc); > + unsigned long flags; > + u32 bit = 1UL << offset; #include <linux/bitops.h> u32 bit = BIT(offset); > + u32 tmp; > + > + spin_lock_irqsave(&hlwd->lock, flags); > + tmp = __raw_readl(hlwd->regs + reg); > + if (value) > + __raw_writel(tmp | bit, hlwd->regs + reg); > + else > + __raw_writel(tmp & ~bit, hlwd->regs + reg); > + spin_unlock_irqrestore(&hlwd->lock, flags); > +} This looks very much like it is reimplementing the stuff we already have in drivers/gpio/gpio-mmio.h. There is even a big endian access flag for the library. And you get so much for free with gpio-mmio. select GPIO_GENERIC in Kconfig the helpers come in from <linux/gpio/driver.h> Look at other drivers for inspiration: git grep bgpio_init If you need IRQ support you should probably have your own file for this driver, but it will be just a few lines of wrapper using bgpio_init() and BGPIOF_BIG_ENDIAN and/or possibly BGPIOF_BIG_ENDIAN_BYTE_ORDER. See the other drivers. Yours, Linus Walleij -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
