On Tue, 28 Jul 2020, at 12:25, Joel Stanley wrote:
> Some FSI capable systems have internal FSI signals, and some have
> external cabled FSI. Software can detect which machine this is by
> reading a jumper GPIO, and also control which pins the signals are
> routed to through a mux GPIO.
>
> This attempts to find the GPIOs at probe time. If they are not present
> in the device tree the driver will not error and continue as before.
>
> The mux GPIO is owned by the FSI driver to ensure it is not modified at
> runtime. The routing jumper obtained as non-exclusive to allow other
> software to inspect it's state.
>
> Signed-off-by: Joel Stanley <joel@xxxxxxxxx>
> ---
> drivers/fsi/fsi-master-aspeed.c | 46 +++++++++++++++++++++++++++++++++
> 1 file changed, 46 insertions(+)
>
> diff --git a/drivers/fsi/fsi-master-aspeed.c b/drivers/fsi/fsi-master-aspeed.c
> index 2b8ca72baeb5..c282de76e6e7 100644
> --- a/drivers/fsi/fsi-master-aspeed.c
> +++ b/drivers/fsi/fsi-master-aspeed.c
> @@ -13,6 +13,7 @@
> #include <linux/regmap.h>
> #include <linux/slab.h>
> #include <linux/iopoll.h>
> +#include <linux/gpio/consumer.h>
>
> #include "fsi-master.h"
>
> @@ -417,6 +418,45 @@ static int aspeed_master_init(struct
> fsi_master_aspeed *aspeed)
> return 0;
> }
>
> +static int tacoma_cabled_fsi_fixup(struct device *dev)
> +{
> + struct gpio_desc *routing_gpio, *mux_gpio;
> + int gpio;
> +
> + /*
> + * The routing GPIO is a jumper indicating we should mux for the
> + * externally connected FSI cable.
> + */
> + routing_gpio = devm_gpiod_get_optional(dev, "fsi-routing",
> + GPIOD_IN | GPIOD_FLAGS_BIT_NONEXCLUSIVE);
> + if (IS_ERR(routing_gpio))
> + return PTR_ERR(routing_gpio);
> + if (!routing_gpio)
> + return 0;
> +
> + mux_gpio = devm_gpiod_get_optional(dev, "fsi-mux", GPIOD_ASIS);
> + if (IS_ERR(mux_gpio))
> + return PTR_ERR(mux_gpio);
> + if (!mux_gpio)
> + return 0;
> +
> + gpio = gpiod_get_value(routing_gpio);
> + if (gpio < 0)
> + return gpio;
> +
> + /* If the routing GPIO is high we should set the mux to low. */
> + if (gpio) {
> + gpiod_direction_output(mux_gpio, 0);
> + dev_info(dev, "FSI configured for external cable\n");
> + } else {
> + gpiod_direction_output(mux_gpio, 1);
> + }
I haven't checked this logic against the hardware but the rest of the patch
looks okay.
Reviewed-by: Andrew Jeffery <andrew@xxxxxxxx>
