Adds an interface for slave device multiplexing using the mux subsystem.
Signed-off-by: Ulrich Hecht <[email protected]>
---
drivers/tty/serdev/Kconfig | 1 +
drivers/tty/serdev/Makefile | 2 +-
drivers/tty/serdev/core.c | 13 ++++++++-
drivers/tty/serdev/mux.c | 66 +++++++++++++++++++++++++++++++++++++++++++++
include/linux/serdev.h | 14 ++++++++--
5 files changed, 92 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..8fd75cb 100644
--- a/drivers/tty/serdev/Kconfig
+++ b/drivers/tty/serdev/Kconfig
@@ -3,6 +3,7 @@
#
menuconfig SERIAL_DEV_BUS
tristate "Serial device bus"
+ select MULTIPLEXER
help
Core support for devices connected via a serial port.
diff --git a/drivers/tty/serdev/Makefile b/drivers/tty/serdev/Makefile
index 0cbdb94..abe5b2a 100644
--- a/drivers/tty/serdev/Makefile
+++ b/drivers/tty/serdev/Makefile
@@ -1,5 +1,5 @@
serdev-objs := core.o
-obj-$(CONFIG_SERIAL_DEV_BUS) += serdev.o
+obj-$(CONFIG_SERIAL_DEV_BUS) += serdev.o 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 8491056..22acd08 100644
--- a/drivers/tty/serdev/core.c
+++ b/drivers/tty/serdev/core.c
@@ -307,7 +307,8 @@ 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;
@@ -370,6 +371,7 @@ static int of_serdev_register_devices(struct
serdev_controller *ctrl)
struct serdev_device *serdev = NULL;
int err;
bool found = false;
+ u32 reg;
for_each_available_child_of_node(ctrl->dev.of_node, node) {
if (!of_get_property(node, "compatible", NULL))
@@ -383,6 +385,11 @@ static int of_serdev_register_devices(struct
serdev_controller *ctrl)
serdev->dev.of_node = node;
+ if (!of_property_read_u32(node, "reg", ®)) {
+ serdev->mux_addr = reg;
+ serdev->nr = reg;
+ }
+
err = serdev_device_add(serdev);
if (err) {
dev_err(&serdev->dev,
@@ -416,6 +423,10 @@ int serdev_controller_add(struct serdev_controller *ctrl)
if (ret)
return ret;
+ if (ctrl->dev.of_node &&
+ of_serdev_register_mux(ctrl) == -EPROBE_DEFER)
+ return -EPROBE_DEFER;
+
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 8f60f11..3ed0f75 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)
@@ -82,6 +84,8 @@ enum serdev_parity {
SERDEV_PARITY_ODD,
};
+int of_serdev_register_mux(struct serdev_controller *ctrl);
+
/*
* serdev controller structures
*/
@@ -103,14 +107,18 @@ 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)
@@ -190,7 +198,7 @@ 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);
@@ -210,6 +218,8 @@ 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
