[PATCH 1/2] gpio: xgene: add support to configure GPIO line as input, output or external IRQ pin

On Fri, Oct 2, 2015 at 4:51 PM, Linus Walleij [off-list ref] wrote:

On Fri, Sep 11, 2015 at 2:22 AM, Y Vo [off-list ref] wrote:

quoted

Add support to configure GPIO line as input, output or external IRQ pin.

Signed-off-by: Y Vo <redacted>

Mostly OK but...

quoted

 #define XGENE_MAX_GPIO_DS              22
 #define XGENE_MAX_GPIO_DS_IRQ          6
+#define XGENE_GPIO8_HWIRQ              0x48
+#define XGENE_GPIO8_IDX                        8

(...)

quoted

+static int xgene_irq_to_line(u32 irq)
+{
+       u32 offset = irq_get_irq_data(irq)->hwirq - XGENE_GPIO8_HWIRQ;
+
+       return (offset < XGENE_MAX_GPIO_DS_IRQ) ?
+                       (offset + XGENE_GPIO8_IDX) : -EINVAL;
+}

What is this hardcoded IRQ 0x48 business?

This is hardware irq number ~ GPIO_DS8. So we use it to get the gpio
number from hwirq. But we are preparing another version which is
better to configure the GPIO lines as interrupt or direction(in/out).

This patch needs kerneldoc for this xgene_irq_to_line() to explain
what exactly is going on, or noone will understand it enough to
debug or refactor the code.

I hope this 0x48 is not some way of compensating for Linux internal
IRQ offsets, that is what irqdomain is for.

Yours,
Linus Walleij