On Thu, Nov 15, 2018 at 2:32 PM Florian Eckert [off-list ref] wrote:

Add a new device driver "gpio-apu" which will handle the GPIOs on APU2
and APU3 devices from PC Engines.

APU2 (https://pcengines.ch/schema/apu2c.pdf page 7):
- G32 is "button_reset" connected to the smd-button on the frontpanel
- G50 is "mpcie2_reset" connected to mPCIe2 reset line
- G51 is "mpcie3_reset" connected to mPCIe3 reset line

APU3 (https://pcengines.ch/schema/apu3c.pdf page 7):
- G32 is "button_reset" connected to the smd-button on the frontpanel
- G50 is "mpcie2_reset" connected to mPCIe2 reset line
- G51 is "mpcie3_reset" connected to mPCIe3 reset line
- G33 is "simswap" connected to SIM switch IC to swap the SIM between
  mPCIe2 and mPCIe3 slot

Signed-off-by: Florian Eckert <redacted>

This is looking better and better! Thanks to everyone helping out
and thanks for your perseverance Florian!

+config GPIO_APU
+       tristate "PC Engines APU2/APU3 GPIO support"
+       depends on X86
+       select GPIO_GENERIC

Excellent idea.

But it seems you are not using this. You would be using
it if you used bgpio_init() but if I understand correctly this
driver cannot use that because this GPIO is something like
one register per pin, correct?

Let me suggest:

+struct apu_gpio_pdata {
+       struct platform_device *pdev;
+       struct gpio_chip *chip;

Make that a real member of this struct and not a pointer.
I.e. just remove the "*".

+static struct apu_gpio_pdata *apu_gpio;

Why a static local? It seems you can just pass around
the pointer.

+static int gpio_apu_get_dir(struct gpio_chip *chip, unsigned int offset)
+{
+       u32 val;
+
+       spin_lock(&apu_gpio->lock);
+
+       val = ~ioread32(apu_gpio->addr[offset]);
+       val = (val >> APU_GPIO_BIT_DIR) & 1;

I would just:

#include <linux/bits.h>

val = ~ioread32(apu_gpio->addr[offset]);
spin_unlock();

return !!(val & BIT(APU_GPIO_BIT_DIR));

This clamps the value to [0,1] in a nice way.

+static int gpio_apu_get_data(struct gpio_chip *chip, unsigned int offset)
+{
+       u32 val;
+
+       spin_lock(&apu_gpio->lock);
+
+       val = ioread32(apu_gpio->addr[offset]);
+
+       spin_unlock(&apu_gpio->lock);
+
+       return (val >> APU_GPIO_BIT_RD) & 1;

return !!(val & BIT(APU_GPIO_BIT_RD));

+       return devm_gpiochip_add_data(&pdev->dev, apu_gpio->chip, NULL);

Instead of passing NULL pas apu_gpio as the last argument and in
all callbacks you can use:

struct apu_gpio_pdata *apu_gpio = gpiochip_get_data(gc);

To get a pointer to the per-instance state container.

Yours,
Linus Walleij