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Subject[PATCH v7-fix] gpio: Add driver for basic memory-mapped GPIO controllers (fix)
On Fri, Sep 24, 2010 at 02:45:35PM -0700, Andrew Morton wrote:
> It would be good to document `bits' and `big_endian_bits', and to
> describe what `lock' locks.

Done.

> > +static int bgpio_dir_in(struct gpio_chip *gc, unsigned int gpio)
> > +{
> > + return 0;
> > +}
>
> hm, what does this mean. The hardware cannot set pin directions to
> "in"?

Nope, 0 is the success. The hardware cannot set pin directions
at all (well, some hw can, but we don't support these yet).

> > + return gpiochip_add(&bgc->gc);
> > +}
>
> If this function returns -EINVAL then much head-scratching will ensue.
> It might make your life easier to emit a diagnostic just before the
> failure so you can work out why it failed.

OK.

Signed-off-by: Anton Vorontsov <cbouatmailru@gmail.com>
---
Thanks!

drivers/gpio/basic_mmio_gpio.c | 22 +++++++++++++++++++---
1 files changed, 19 insertions(+), 3 deletions(-)
diff --git a/drivers/gpio/basic_mmio_gpio.c b/drivers/gpio/basic_mmio_gpio.c
index c2c11e7..3addea6 100644
--- a/drivers/gpio/basic_mmio_gpio.c
+++ b/drivers/gpio/basic_mmio_gpio.c
@@ -66,12 +66,23 @@ struct bgpio_chip {
void __iomem *reg_dat;
void __iomem *reg_set;
void __iomem *reg_clr;
- spinlock_t lock;

+ /* Number of bits (GPIOs): <register width> * 8. */
int bits;
+
+ /*
+ * Some GPIO controllers work with the big-endian bits notation,
+ * e.g. in a 8-bits register, GPIO7 is the least significant bit.
+ */
int big_endian_bits;

- /* shadowed data register to clear/set bits safely */
+ /*
+ * Used to lock bgpio_chip->data. Also, this is needed to keep
+ * shadowed and real data registers writes together.
+ */
+ spinlock_t lock;
+
+ /* Shadowed data register to clear/set bits safely. */
unsigned long data;
};

@@ -181,6 +192,7 @@ static int __devinit bgpio_probe(struct platform_device *pdev)
struct resource *res_clr;
resource_size_t dat_sz;
int bits;
+ int ret;

res_dat = platform_get_resource_byname(pdev, IORESOURCE_MEM, "dat");
if (!res_dat)
@@ -238,7 +250,11 @@ static int __devinit bgpio_probe(struct platform_device *pdev)

dev_set_drvdata(dev, bgc);

- return gpiochip_add(&bgc->gc);
+ ret = gpiochip_add(&bgc->gc);
+ if (ret)
+ dev_err(dev, "gpiochip_add() failed: %d\n", ret);
+
+ return ret;
}

static int __devexit bgpio_remove(struct platform_device *pdev)
--
1.7.0.5


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