[PATCH linux dev-5.3 1/2] fsi: aspeed: Configure optional GPIOs

[Andrew Jeffery]

On Tue, 15 Oct 2019, at 10:57, Andrew Jeffery wrote:
> 
> 
> On Mon, 14 Oct 2019, at 18:16, Joel Stanley wrote:
> > On Tacoma the enable and mux GPIOs allow the BMC to enable FSI and
> > control if the clock and data should come from the BMC, or from the
> > debug connector.
> > 
> > Configure these as optional GPIOs which will fail without error for
> > systems that do not have these GPIOs in their device tree.
> > 
> > Signed-off-by: Joel Stanley <joel at jms.id.au>
> > ---
> >  drivers/fsi/fsi-master-aspeed.c | 30 ++++++++++++++++++++++++++++++
> >  1 file changed, 30 insertions(+)
> > 
> > diff --git a/drivers/fsi/fsi-master-aspeed.c b/drivers/fsi/fsi-master-aspeed.c
> > index 6496d2972944..2048e38e7200 100644
> > --- a/drivers/fsi/fsi-master-aspeed.c
> > +++ b/drivers/fsi/fsi-master-aspeed.c
> > @@ -14,6 +14,7 @@
> >  #include <linux/regmap.h>
> >  #include <linux/slab.h>
> >  #include <linux/iopoll.h>
> > +#include <linux/gpio/consumer.h>
> >  
> >  #include "fsi-master.h"
> >  
> > @@ -85,6 +86,9 @@ struct fsi_master_aspeed {
> >  	void __iomem		*base;
> >  	struct clk		*clk;
> >  
> > +	struct gpio_desc	*gpio_enable;
> > +	struct gpio_desc	*gpio_mux;
> > +
> >  	struct dentry		*debugfs_dir;
> >  	struct fsi_master_aspeed_debugfs_entry debugfs[FSI_NUM_DEBUGFS_ENTRIES];
> >  };
> > @@ -471,6 +475,30 @@ DEFINE_DEBUGFS_ATTRIBUTE(fsi_master_aspeed_debugfs_ops,
> >  			 fsi_master_aspeed_debugfs_get,
> >  			 fsi_master_aspeed_debugfs_set, "0x%08llx\n");
> >  
> > +static int aspeed_master_gpio_init(struct fsi_master_aspeed *master)
> > +{
> > +	struct device *dev = master->dev;
> > +	struct gpio_desc *gpio;
> > +
> > +	gpio = devm_gpiod_get_optional(dev, "fsi-enable", 0);
> > +	if (IS_ERR(gpio)) {
> 
> devm_gpiod_get_option() returns NULL if the GPIO isn't defined, and
> interfaces like gpiod_direction_output(...) return 0 if the descriptor is
> NULL. The design point of the _optional() interfaces is that it makes the
> error handling unnecessary because we know the GPIO might be absent.
> 
> The pattern is also wrong in fsi-master-ast-cf and probably fsi-master-gpio.

Actually, disregard that, NULL is only returned for -ENOENT but there may
be other errors. Sorry for the noise.