On Mon, Jul 17, 2017 at 10:24 AM, Ulrich Hecht
<ulrich.hecht+renesas@xxxxxxxxx> wrote:
> Adds an interface for slave device multiplexing using the mux subsystem.
>
> Signed-off-by: Ulrich Hecht <ulrich.hecht+renesas@xxxxxxxxx>
> ---
> drivers/tty/serdev/Kconfig | 3 +++
> drivers/tty/serdev/Makefile | 1 +
> drivers/tty/serdev/core.c | 14 +++++++++-
> drivers/tty/serdev/mux.c | 66 +++++++++++++++++++++++++++++++++++++++++++++
> include/linux/serdev.h | 16 ++++++++---
> 5 files changed, 96 insertions(+), 4 deletions(-)
> create mode 100644 drivers/tty/serdev/mux.c
>
> diff --git a/drivers/tty/serdev/Kconfig b/drivers/tty/serdev/Kconfig
> index cdc6b82..9096b71 100644
> --- a/drivers/tty/serdev/Kconfig
> +++ b/drivers/tty/serdev/Kconfig
> @@ -13,4 +13,7 @@ config SERIAL_DEV_CTRL_TTYPORT
> depends on TTY
> depends on SERIAL_DEV_BUS != m
>
> +config SERIAL_DEV_MUX
> + bool "Serial device multiplexer support"
I think this breaks for modules.
I'm inclined to just keep mux support in the core.
> +
> endif
> diff --git a/drivers/tty/serdev/Makefile b/drivers/tty/serdev/Makefile
> index 0cbdb94..d713381 100644
> --- a/drivers/tty/serdev/Makefile
> +++ b/drivers/tty/serdev/Makefile
> @@ -1,5 +1,6 @@
> serdev-objs := core.o
>
> obj-$(CONFIG_SERIAL_DEV_BUS) += serdev.o
> +obj-$(CONFIG_SERIAL_DEV_MUX) += mux.o
>
> obj-$(CONFIG_SERIAL_DEV_CTRL_TTYPORT) += serdev-ttyport.o
> diff --git a/drivers/tty/serdev/core.c b/drivers/tty/serdev/core.c
> index 1fbaa4c..92c5bfa 100644
> --- a/drivers/tty/serdev/core.c
> +++ b/drivers/tty/serdev/core.c
> @@ -305,7 +305,8 @@ struct serdev_device *serdev_device_alloc(struct serdev_controller *ctrl)
> return NULL;
>
> serdev->ctrl = ctrl;
> - ctrl->serdev = serdev;
> + if (!ctrl->serdev)
> + ctrl->serdev = serdev;
> device_initialize(&serdev->dev);
> serdev->dev.parent = &ctrl->dev;
> serdev->dev.bus = &serdev_bus_type;
> @@ -368,6 +369,8 @@ static int of_serdev_register_devices(struct serdev_controller *ctrl)
> struct serdev_device *serdev = NULL;
> int err;
> bool found = false;
> + int nr = 0;
> + u32 reg;
>
> for_each_available_child_of_node(ctrl->dev.of_node, node) {
> if (!of_get_property(node, "compatible", NULL))
> @@ -380,6 +383,10 @@ static int of_serdev_register_devices(struct serdev_controller *ctrl)
> continue;
>
> serdev->dev.of_node = node;
> + serdev->nr = nr++;
> +
> + if (!of_property_read_u32(node, "reg", ®))
> + serdev->mux_addr = reg;
Perhaps nr should just be assigned reg value.
>
> err = serdev_device_add(serdev);
> if (err) {
> @@ -414,6 +421,11 @@ int serdev_controller_add(struct serdev_controller *ctrl)
> if (ret)
> return ret;
>
> +#ifdef CONFIG_SERIAL_DEV_MUX
> + if (of_serdev_register_mux(ctrl) == -EPROBE_DEFER)
> + return -EPROBE_DEFER;
> +#endif
> +
> ret = of_serdev_register_devices(ctrl);
> if (ret)
> goto out_dev_del;
> diff --git a/drivers/tty/serdev/mux.c b/drivers/tty/serdev/mux.c
> new file mode 100644
> index 0000000..fc9405b
> --- /dev/null
> +++ b/drivers/tty/serdev/mux.c
> @@ -0,0 +1,66 @@
> +/*
> + * Copyright (C) 2017 Ulrich Hecht
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 and
> + * only version 2 as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> + * GNU General Public License for more details.
> + */
> +
> +#include <linux/mux/consumer.h>
> +#include <linux/mux/driver.h>
> +#include <linux/of_gpio.h>
> +#include <linux/serdev.h>
> +#include <linux/slab.h>
> +
> +int serdev_device_mux_select(struct serdev_device *serdev)
> +{
> + struct mux_control *mux = serdev->ctrl->mux;
> + int ret;
> +
> + if (!mux)
> + return -EINVAL;
> +
> + ret = mux_control_select(mux, serdev->mux_addr);
> + serdev->ctrl->mux_do_not_deselect = ret < 0;
> +
> + serdev->ctrl->serdev = serdev;
> +
> + return ret;
> +}
> +
> +int serdev_device_mux_deselect(struct serdev_device *serdev)
> +{
> + struct mux_control *mux = serdev->ctrl->mux;
> +
> + if (!mux)
> + return -EINVAL;
> +
> + if (!serdev->ctrl->mux_do_not_deselect)
> + return mux_control_deselect(mux);
> + else
> + return 0;
> +}
> +
> +int of_serdev_register_mux(struct serdev_controller *ctrl)
> +{
> + struct mux_control *mux;
> + struct device *dev = &ctrl->dev;
> +
> + mux = devm_mux_control_get(dev, NULL);
> +
> + if (IS_ERR(mux)) {
> + if (PTR_ERR(mux) != -EPROBE_DEFER)
> + dev_err(dev, "failed to get control mux\n");
> + return PTR_ERR(mux);
> + }
> +
> + ctrl->mux = mux;
> +
> + return 0;
> +}
> +
> diff --git a/include/linux/serdev.h b/include/linux/serdev.h
> index 8b67fcd..26d5994 100644
> --- a/include/linux/serdev.h
> +++ b/include/linux/serdev.h
> @@ -17,6 +17,7 @@
> #include <linux/device.h>
> #include <linux/termios.h>
> #include <linux/delay.h>
> +#include <linux/rtmutex.h>
>
> struct serdev_controller;
> struct serdev_device;
> @@ -51,6 +52,7 @@ struct serdev_device {
> const struct serdev_device_ops *ops;
> struct completion write_comp;
> struct mutex write_lock;
> + int mux_addr;
> };
>
> static inline struct serdev_device *to_serdev_device(struct device *d)
> @@ -76,6 +78,8 @@ static inline struct serdev_device_driver *to_serdev_device_driver(struct device
> return container_of(d, struct serdev_device_driver, driver);
> }
>
> +int of_serdev_register_mux(struct serdev_controller *ctrl);
> +
> /*
> * serdev controller structures
> */
> @@ -97,14 +101,18 @@ struct serdev_controller_ops {
> * struct serdev_controller - interface to the serdev controller
> * @dev: Driver model representation of the device.
> * @nr: number identifier for this controller/bus.
> - * @serdev: Pointer to slave device for this controller.
> + * @serdev: Pointer to active slave device for this controller.
> * @ops: Controller operations.
> + * @mux: Slave multiplexer control.
> + * @mux_do_not_deselect: Set if slave selection failed.
> */
> struct serdev_controller {
> struct device dev;
> unsigned int nr;
> struct serdev_device *serdev;
> const struct serdev_controller_ops *ops;
> + struct mux_control *mux;
> + int mux_do_not_deselect;
> };
>
> static inline struct serdev_controller *to_serdev_controller(struct device *d)
> @@ -172,7 +180,7 @@ static inline void serdev_controller_write_wakeup(struct serdev_controller *ctrl
> {
> struct serdev_device *serdev = ctrl->serdev;
>
> - if (!serdev || !serdev->ops->write_wakeup)
> + if (!serdev || !serdev->ops || !serdev->ops->write_wakeup)
When is ops ever NULL? Should be a separate change AFIACT.
> return;
>
> serdev->ops->write_wakeup(serdev);
> @@ -184,7 +192,7 @@ static inline int serdev_controller_receive_buf(struct serdev_controller *ctrl,
> {
> struct serdev_device *serdev = ctrl->serdev;
>
> - if (!serdev || !serdev->ops->receive_buf)
> + if (!serdev || !serdev->ops || !serdev->ops->receive_buf)
> return -EINVAL;
>
> return serdev->ops->receive_buf(serdev, data, count);
> @@ -204,6 +212,8 @@ void serdev_device_write_wakeup(struct serdev_device *);
> int serdev_device_write(struct serdev_device *, const unsigned char *, size_t, unsigned long);
> void serdev_device_write_flush(struct serdev_device *);
> int serdev_device_write_room(struct serdev_device *);
> +int serdev_device_mux_select(struct serdev_device *);
> +int serdev_device_mux_deselect(struct serdev_device *);
>
> /*
> * serdev device driver functions
> --
> 2.7.4
>
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