On Wed, 2014-12-24 at 00:22 -0800, thloh@altera.com wrote:

Adds a new driver for Altera soft GPIO IP. The driver is able to
do read/write and allows GPIO to be a interrupt controller.

Some trivial comments, some not quite so trivial.

[]

+static int altera_gpio_irq_set_type(struct irq_data *d,
+				   unsigned int type)
+{
+	struct altera_gpio_chip *altera_gc = irq_data_get_irq_chip_data(d);
+
+	altera_gc = irq_data_get_irq_chip_data(d);

I presume this multiple initialization of altera_gc
is unnecessary duplication.

+static void altera_gpio_irq_edge_handler(unsigned int irq,
+					struct irq_desc *desc)
+{
+	struct altera_gpio_chip *altera_gc;
+	struct irq_chip *chip;
+	struct of_mm_gpio_chip *mm_gc;
+	unsigned long status;
+	int i;
+
+	altera_gc = irq_desc_get_handler_data(desc);
+	chip = irq_desc_get_chip(desc);
+	mm_gc = &altera_gc->mmchip;
+
+	chained_irq_enter(chip, desc);
+
+	while ((status =
+	      (readl(mm_gc->regs + ALTERA_GPIO_EDGE_CAP) &
+	      readl(mm_gc->regs + ALTERA_GPIO_IRQ_MASK)))) {
+		writel(status, mm_gc->regs + ALTERA_GPIO_EDGE_CAP);
+		for_each_set_bit(i, &status, mm_gc->gc.ngpio) {
+			generic_handle_irq(
+				irq_find_mapping(altera_gc->mmchip.gc.irqdomain
+						, i));

That's kind of unpleasant to read.
It might be better to use a separate these statements
and use a temporary for irq_find_mapping()

+static void altera_gpio_irq_leveL_high_handler(unsigned int irq,
+					      struct irq_desc *desc)
+{
+	struct altera_gpio_chip *altera_gc;
+	struct irq_chip *chip;
+	struct of_mm_gpio_chip *mm_gc;
+	unsigned long status;
+	int i;
+
+	altera_gc = irq_desc_get_handler_data(desc);
+	chip = irq_desc_get_chip(desc);
+	mm_gc = &altera_gc->mmchip;
+
+	chained_irq_enter(chip, desc);
+
+	status = readl(mm_gc->regs + ALTERA_GPIO_DATA);
+	status &= readl(mm_gc->regs + ALTERA_GPIO_IRQ_MASK);
+
+	for_each_set_bit(i, &status, mm_gc->gc.ngpio) {
+		generic_handle_irq(
+			irq_find_mapping(altera_gc->mmchip.gc.irqdomain, i));

Maybe a temporary here too

+int altera_gpio_probe(struct platform_device *pdev)
+{
+	struct device_node *node = pdev->dev.of_node;
+	int id, reg, ret;
+	struct altera_gpio_chip *altera_gc;
+
+	altera_gc = devm_kzalloc(&pdev->dev, sizeof(*altera_gc), GFP_KERNEL);
+
+	if (altera_gc == NULL)
+		return -ENOMEM;

No blank line after the devm_kzalloc please and
	if (!altera_gc)
is more common.

+	if (altera_gc->interrupt_trigger == IRQ_TYPE_LEVEL_HIGH) {
+		gpiochip_set_chained_irqchip(&altera_gc->mmchip.gc,
+			&altera_irq_chip,
+			altera_gc->mapped_irq,
+			altera_gpio_irq_leveL_high_handler);
+	} else {
+		gpiochip_set_chained_irqchip(&altera_gc->mmchip.gc,
+			&altera_irq_chip,
+			altera_gc->mapped_irq,
+			altera_gpio_irq_edge_handler);
+	}

Sometimes using a ?: ternary is smaller code

	gpiochip_set_chained_irqchip(&altera_gc->mmchip.gc,
				     &altera_irq_chip,
				     altera_gc->mapped_irq,
				     altera_gc->interrupt_trigger == IRQ_TYPE_LEVEL_HIGH ?
				     altera_gpio_irq_leveL_high_handler :
				     altera_gpio_irq_edge_handler);