We want to enable runtime PM for serial port device drivers in a generic
way. To do this, we want to have the serial core layer manage the
registered physical serial controller devices.
To do this, let's set up a struct bus and struct device for the serial
core controller as suggested by Greg and Jiri. The serial core controller
devices are children of the physical serial port device. The serial core
controller device is needed to support multiple different kind of ports
connected to single physical serial port device.
Let's also set up a struct device for the serial core port. The serial
core port instances are children of the serial core controller device.
With the serial core port device we can now flush pending TX on the
runtime PM resume as suggested by Johan.
Suggested-by: Andy Shevchenko <[email protected]>
Suggested-by: Greg Kroah-Hartman <[email protected]>
Suggested-by: Jiri Slaby <[email protected]>
Suggested-by: Johan Hovold <[email protected]>
Signed-off-by: Tony Lindgren <[email protected]>
---
Changes since v9:
- Built in serial_base and core related components into serial_base.ko as
suggested by Greg. We now have module_init only in serial_base.c that
calls serial_base_ctrl_init() and serial_base_port_init(). I renamed
serial_bus.c to serial_base_bus.c to build serial_base.ko. Note that
if we wanted to build these into serial_core.ko, renaming serial_core.c
would be needed which is not necessarily nice for folks that may have
pending patches
- Dropped string comparison for ctrl and port, and switched to using
struct device_type as suggested by Greg
- Dropped port->state checks in serial_base_get_port() as noted by
Greg
- Dropped EXPORT_SYMBOL_NS(), these are no longer needed with components
built into serial_base.ko. I also noticed that we have some dependency
loops if components are not built into serial_base.ko. And we would
have hard time later on moving port specific functions to serial_port.c
for example
- Dropped checks for negative ctrl_id in serial_core_ctrl_find() as
suggested by Greg
- Stopped resetting ctrl_id in serial_core_remove_one_port(), instead
let's properly init it in serial8250_init_port(). The ctrl_id is
optionally passed to uart_add_one_port() and zero otherwise
- Moved port_mutex and UPF_DEAD handling from serial_core_add_one_port()
to serial_core_register_port() to simplify things a bit
- Updated license and copyright as suggested by Greg
- Dropped Andy's reviewed-by, things still changed quite a bit
Changes since v8:
- Drop unnecessary free for name noticed by Andy, the name is freed
on put_device()
- Cosmetic fix for comments in serial_port.c noted by Andy
- Spelling fix for word uninitialized in serial_base_get_port()
Changes since v7:
- Add release() put_device() to serial_base.c as noted by Andy
- Make struct serial_base_device private to serial_base.c by adding
serial_base_get_port()
- Add more comments to __uart_start()
- Coding style improvments for serial_base.c from Andy
Changes since v6:
- Fix up a memory leak and a bunch of issues in serial_base.c as noted
by Andy
- Replace bool with new_ctrl_dev for freeing the added device on
error path
- Drop unused pm ops for serial_ctrl.c as noted by kernel test robot
- Drop documentation updates for acpi devices for now to avoid a merge
conflict and make testing easier between -rc2 and Linux next
Changes since v5:
- Replace platform bus and device with bus_add() and device_add(),
Greg did not like platform bus and device here. This also gets
rid of the need for platform data with struct serial_base_device,
see new file serial_base.c
- Update documentation to drop reference to struct uart_device as
suggested by Andy
Changes since v4:
- Fix issue noted by Ilpo by calling serial_core_add_one_port() after
the devices are created
Changes since v3:
- Simplify things by adding a serial core control device as the child of
the physical serial port as suggested by Jiri
- Drop the tinkering of the physical serial port device for runtime PM.
Serial core just needs to manage port->port_dev with the addition of
the serial core control device and the device hierarchy will keep the
pysical serial port device enabled as needed
- Simplify patch description with all the runtime PM tinkering gone
- Coding style improvments as noted by Andy
- Post as a single RFC patch as we're close to the merge window
Changes since v2:
- Make each serial port a proper device as suggested by Greg. This is
a separate patch that flushes the TX on runtime PM resume
Changes since v1:
- Use kref as suggested by Andy
- Fix memory leak on error as noted by Andy
- Use use unsigned char for supports_autosuspend as suggested by Andy
- Coding style improvments as suggested by Andy
---
drivers/tty/serial/8250/8250_core.c | 1 +
drivers/tty/serial/8250/8250_port.c | 1 +
drivers/tty/serial/Makefile | 3 +-
drivers/tty/serial/serial_base.h | 35 +++++
drivers/tty/serial/serial_base_bus.c | 179 +++++++++++++++++++++++++
drivers/tty/serial/serial_core.c | 188 +++++++++++++++++++++++----
drivers/tty/serial/serial_ctrl.c | 68 ++++++++++
drivers/tty/serial/serial_port.c | 105 +++++++++++++++
include/linux/serial_core.h | 4 +-
9 files changed, 557 insertions(+), 27 deletions(-)
create mode 100644 drivers/tty/serial/serial_base.h
create mode 100644 drivers/tty/serial/serial_base_bus.c
create mode 100644 drivers/tty/serial/serial_ctrl.c
create mode 100644 drivers/tty/serial/serial_port.c
diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c
--- a/drivers/tty/serial/8250/8250_core.c
+++ b/drivers/tty/serial/8250/8250_core.c
@@ -996,6 +996,7 @@ int serial8250_register_8250_port(const struct uart_8250_port *up)
if (uart->port.dev)
uart_remove_one_port(&serial8250_reg, &uart->port);
+ uart->port.ctrl_id = up->port.ctrl_id;
uart->port.iobase = up->port.iobase;
uart->port.membase = up->port.membase;
uart->port.irq = up->port.irq;
diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -3292,6 +3292,7 @@ void serial8250_init_port(struct uart_8250_port *up)
struct uart_port *port = &up->port;
spin_lock_init(&port->lock);
+ port->ctrl_id = 0;
port->ops = &serial8250_pops;
port->has_sysrq = IS_ENABLED(CONFIG_SERIAL_8250_CONSOLE);
diff --git a/drivers/tty/serial/Makefile b/drivers/tty/serial/Makefile
--- a/drivers/tty/serial/Makefile
+++ b/drivers/tty/serial/Makefile
@@ -3,7 +3,8 @@
# Makefile for the kernel serial device drivers.
#
-obj-$(CONFIG_SERIAL_CORE) += serial_core.o
+obj-$(CONFIG_SERIAL_CORE) += serial_base.o
+serial_base-objs := serial_core.o serial_base_bus.o serial_ctrl.o serial_port.o
obj-$(CONFIG_SERIAL_EARLYCON) += earlycon.o
obj-$(CONFIG_SERIAL_EARLYCON_SEMIHOST) += earlycon-semihost.o
diff --git a/drivers/tty/serial/serial_base.h b/drivers/tty/serial/serial_base.h
new file mode 100644
--- /dev/null
+++ b/drivers/tty/serial/serial_base.h
@@ -0,0 +1,35 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Serial core related functions, serial port device drivers do not need this.
+ *
+ * Copyright (C) 2023 Texas Instruments Incorporated - https://www.ti.com/
+ * Author: Tony Lindgren <[email protected]>
+ */
+
+struct uart_driver;
+struct uart_port;
+struct device_driver;
+struct device;
+
+int serial_base_ctrl_init(void);
+void serial_base_ctrl_exit(void);
+
+int serial_base_port_init(void);
+void serial_base_port_exit(void);
+
+int serial_base_driver_register(struct device_driver *driver);
+void serial_base_driver_unregister(struct device_driver *driver);
+
+struct device *serial_base_ctrl_add(struct uart_port *port,
+ struct device *parent_dev);
+struct device *serial_base_port_add(struct uart_port *port,
+ struct device *parent_dev);
+void serial_base_device_remove(struct device *dev);
+
+struct uart_port *serial_base_get_port(struct device *dev);
+
+int serial_ctrl_register_port(struct uart_driver *drv, struct uart_port *port);
+void serial_ctrl_unregister_port(struct uart_driver *drv, struct uart_port *port);
+
+int serial_core_register_port(struct uart_driver *drv, struct uart_port *port);
+void serial_core_unregister_port(struct uart_driver *drv, struct uart_port *port);
diff --git a/drivers/tty/serial/serial_base_bus.c b/drivers/tty/serial/serial_base_bus.c
new file mode 100644
--- /dev/null
+++ b/drivers/tty/serial/serial_base_bus.c
@@ -0,0 +1,179 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Serial base bus layer for controllers
+ *
+ * Copyright (C) 2023 Texas Instruments Incorporated - https://www.ti.com/
+ * Author: Tony Lindgren <[email protected]>
+ *
+ * The serial core bus manages the serial core controller instances.
+ */
+
+#include <linux/container_of.h>
+#include <linux/device.h>
+#include <linux/module.h>
+#include <linux/serial_core.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+
+#include "serial_base.h"
+
+struct serial_base_device {
+ struct device dev;
+ struct uart_port *port;
+};
+
+#define to_serial_base_device(d) container_of((d), struct serial_base_device, dev)
+
+struct uart_port *serial_base_get_port(struct device *dev)
+{
+ struct serial_base_device *sbd;
+
+ if (!dev)
+ return NULL;
+
+ sbd = to_serial_base_device(dev);
+
+ return sbd->port;
+}
+
+static int serial_base_match(struct device *dev, struct device_driver *drv)
+{
+ int len = strlen(drv->name);
+
+ return !strncmp(dev_name(dev), drv->name, len);
+}
+
+static struct bus_type serial_base_bus_type = {
+ .name = "serial-base",
+ .match = serial_base_match,
+};
+
+int serial_base_driver_register(struct device_driver *driver)
+{
+ driver->bus = &serial_base_bus_type;
+
+ return driver_register(driver);
+}
+
+void serial_base_driver_unregister(struct device_driver *driver)
+{
+ driver_unregister(driver);
+}
+
+static void serial_base_release(struct device *dev)
+{
+ struct serial_base_device *sbd = to_serial_base_device(dev);
+
+ kfree(sbd);
+}
+
+static const struct device_type serial_ctrl_type = {
+ .name = "ctrl",
+};
+
+static const struct device_type serial_port_type = {
+ .name = "port",
+};
+
+static struct device *serial_base_device_add(struct uart_port *port,
+ struct device *parent_dev,
+ const struct device_type *type)
+{
+ struct serial_base_device *sbd;
+ int err, id;
+
+ sbd = kzalloc(sizeof(*sbd), GFP_KERNEL);
+ if (!sbd)
+ return NULL;
+
+ device_initialize(&sbd->dev);
+ sbd->dev.type = type;
+ sbd->dev.parent = parent_dev;
+ sbd->dev.bus = &serial_base_bus_type;
+ sbd->dev.release = &serial_base_release;
+
+ if (type == &serial_ctrl_type) {
+ id = port->ctrl_id;
+ } else if (type == &serial_port_type) {
+ id = port->line;
+ sbd->port = port;
+ }
+
+ err = dev_set_name(&sbd->dev, "%s.%s.%d", type->name, dev_name(port->dev), id);
+ if (err)
+ goto err_free_dev;
+
+ err = device_add(&sbd->dev);
+ if (err)
+ goto err_put_device;
+
+ return &sbd->dev;
+
+err_put_device:
+ put_device(&sbd->dev);
+
+err_free_dev:
+ kfree(sbd);
+
+ return NULL;
+}
+
+struct device *serial_base_ctrl_add(struct uart_port *port,
+ struct device *parent_dev)
+{
+ return serial_base_device_add(port, parent_dev, &serial_ctrl_type);
+}
+
+struct device *serial_base_port_add(struct uart_port *port,
+ struct device *parent_dev)
+{
+ return serial_base_device_add(port, parent_dev, &serial_port_type);
+}
+
+void serial_base_device_remove(struct device *dev)
+{
+ if (!dev)
+ return;
+
+ device_del(dev);
+}
+
+static int serial_base_init(void)
+{
+ int ret;
+
+ ret = bus_register(&serial_base_bus_type);
+ if (ret)
+ return ret;
+
+ ret = serial_base_ctrl_init();
+ if (ret)
+ goto err_bus_unregister;
+
+ ret = serial_base_port_init();
+ if (ret)
+ goto err_ctrl_exit;
+
+ return 0;
+
+err_ctrl_exit:
+ serial_base_ctrl_exit();
+
+err_bus_unregister:
+ bus_unregister(&serial_base_bus_type);
+
+ return ret;
+}
+module_init(serial_base_init);
+
+static void serial_base_exit(void)
+{
+ serial_base_port_exit();
+ serial_base_ctrl_exit();
+ bus_unregister(&serial_base_bus_type);
+}
+module_exit(serial_base_exit);
+
+MODULE_AUTHOR("Tony Lindgren <[email protected]>");
+MODULE_DESCRIPTION("Serial core bus");
+MODULE_LICENSE("GPL");
diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -17,6 +17,7 @@
#include <linux/gpio/consumer.h>
#include <linux/kernel.h>
#include <linux/of.h>
+#include <linux/pm_runtime.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/device.h>
@@ -31,6 +32,8 @@
#include <linux/irq.h>
#include <linux/uaccess.h>
+#include "serial_base.h"
+
/*
* This is used to lock changes in serial line configuration.
*/
@@ -134,9 +137,30 @@ static void __uart_start(struct tty_struct *tty)
{
struct uart_state *state = tty->driver_data;
struct uart_port *port = state->uart_port;
+ struct device *port_dev;
+ int err;
- if (port && !(port->flags & UPF_DEAD) && !uart_tx_stopped(port))
+ if (!port || port->flags & UPF_DEAD || uart_tx_stopped(port))
+ return;
+
+ port_dev = port->port_dev;
+
+ /* Increment the runtime PM usage count for the active check below */
+ err = pm_runtime_get(port_dev);
+ if (err < 0) {
+ pm_runtime_put_noidle(port_dev);
+ return;
+ }
+
+ /*
+ * Start TX if enabled, and kick runtime PM. If the device is not
+ * enabled, serial_port_runtime_resume() calls start_tx() again
+ * after enabling the device.
+ */
+ if (pm_runtime_active(port_dev))
port->ops->start_tx(port);
+ pm_runtime_mark_last_busy(port_dev);
+ pm_runtime_put_autosuspend(port_dev);
}
static void uart_start(struct tty_struct *tty)
@@ -3042,7 +3066,7 @@ static const struct attribute_group tty_dev_attr_group = {
};
/**
- * uart_add_one_port - attach a driver-defined port structure
+ * serial_core_add_one_port - attach a driver-defined port structure
* @drv: pointer to the uart low level driver structure for this port
* @uport: uart port structure to use for this port.
*
@@ -3051,8 +3075,9 @@ static const struct attribute_group tty_dev_attr_group = {
* This allows the driver @drv to register its own uart_port structure with the
* core driver. The main purpose is to allow the low level uart drivers to
* expand uart_port, rather than having yet more levels of structures.
+ * Caller must hold port_mutex.
*/
-int uart_add_one_port(struct uart_driver *drv, struct uart_port *uport)
+static int serial_core_add_one_port(struct uart_driver *drv, struct uart_port *uport)
{
struct uart_state *state;
struct tty_port *port;
@@ -3066,7 +3091,6 @@ int uart_add_one_port(struct uart_driver *drv, struct uart_port *uport)
state = drv->state + uport->line;
port = &state->port;
- mutex_lock(&port_mutex);
mutex_lock(&port->mutex);
if (state->uart_port) {
ret = -EINVAL;
@@ -3131,21 +3155,14 @@ int uart_add_one_port(struct uart_driver *drv, struct uart_port *uport)
uport->line);
}
- /*
- * Ensure UPF_DEAD is not set.
- */
- uport->flags &= ~UPF_DEAD;
-
out:
mutex_unlock(&port->mutex);
- mutex_unlock(&port_mutex);
return ret;
}
-EXPORT_SYMBOL(uart_add_one_port);
/**
- * uart_remove_one_port - detach a driver defined port structure
+ * serial_core_remove_one_port - detach a driver defined port structure
* @drv: pointer to the uart low level driver structure for this port
* @uport: uart port structure for this port
*
@@ -3153,8 +3170,10 @@ EXPORT_SYMBOL(uart_add_one_port);
*
* This unhooks (and hangs up) the specified port structure from the core
* driver. No further calls will be made to the low-level code for this port.
+ * Caller must hold port_mutex.
*/
-int uart_remove_one_port(struct uart_driver *drv, struct uart_port *uport)
+static int serial_core_remove_one_port(struct uart_driver *drv,
+ struct uart_port *uport)
{
struct uart_state *state = drv->state + uport->line;
struct tty_port *port = &state->port;
@@ -3162,12 +3181,6 @@ int uart_remove_one_port(struct uart_driver *drv, struct uart_port *uport)
struct tty_struct *tty;
int ret = 0;
- mutex_lock(&port_mutex);
-
- /*
- * Mark the port "dead" - this prevents any opens from
- * succeeding while we shut down the port.
- */
mutex_lock(&port->mutex);
uart_port = uart_port_check(state);
if (uart_port != uport)
@@ -3176,10 +3189,8 @@ int uart_remove_one_port(struct uart_driver *drv, struct uart_port *uport)
if (!uart_port) {
mutex_unlock(&port->mutex);
- ret = -EINVAL;
- goto out;
+ return -EINVAL;
}
- uport->flags |= UPF_DEAD;
mutex_unlock(&port->mutex);
/*
@@ -3211,18 +3222,16 @@ int uart_remove_one_port(struct uart_driver *drv, struct uart_port *uport)
* Indicate that there isn't a port here anymore.
*/
uport->type = PORT_UNKNOWN;
+ uport->port_dev = NULL;
mutex_lock(&port->mutex);
WARN_ON(atomic_dec_return(&state->refcount) < 0);
wait_event(state->remove_wait, !atomic_read(&state->refcount));
state->uart_port = NULL;
mutex_unlock(&port->mutex);
-out:
- mutex_unlock(&port_mutex);
return ret;
}
-EXPORT_SYMBOL(uart_remove_one_port);
/**
* uart_match_port - are the two ports equivalent?
@@ -3257,6 +3266,135 @@ bool uart_match_port(const struct uart_port *port1,
}
EXPORT_SYMBOL(uart_match_port);
+/*
+ * Find a registered serial core controller device if one exists. Returns
+ * the first device matching the ctrl_id. Caller must hold port_mutex.
+ */
+static struct device *serial_core_ctrl_find(struct uart_driver *drv,
+ struct device *phys_dev,
+ int ctrl_id)
+{
+ struct uart_state *state;
+ int i;
+
+ lockdep_assert_held(&port_mutex);
+
+ for (i = 0; i < drv->nr; i++) {
+ state = drv->state + i;
+ if (!state->uart_port || !state->uart_port->port_dev)
+ continue;
+
+ if (state->uart_port->dev == phys_dev &&
+ state->uart_port->ctrl_id == ctrl_id)
+ return state->uart_port->port_dev->parent;
+ }
+
+ return NULL;
+}
+
+static struct device *serial_core_ctrl_device_add(struct uart_port *port)
+{
+ return serial_base_ctrl_add(port, port->dev);
+}
+
+static int serial_core_port_device_add(struct device *ctrl_dev, struct uart_port *port)
+{
+ struct device *dev;
+
+ dev = serial_base_port_add(port, ctrl_dev);
+ if (IS_ERR(dev))
+ return PTR_ERR(dev);
+
+ port->port_dev = dev;
+
+ return 0;
+}
+
+/*
+ * Initialize a serial core port device, and a controller device if needed.
+ */
+int serial_core_register_port(struct uart_driver *drv, struct uart_port *port)
+{
+ struct device *ctrl_dev, *new_ctrl_dev = NULL;
+ int ret;
+
+ mutex_lock(&port_mutex);
+
+ /*
+ * Prevent serial_port_runtime_resume() from trying to use the port
+ * until serial_core_add_one_port() has completed
+ */
+ port->flags |= UPF_DEAD;
+
+ /* Inititalize a serial core controller device if needed */
+ ctrl_dev = serial_core_ctrl_find(drv, port->dev, port->ctrl_id);
+ if (!ctrl_dev) {
+ new_ctrl_dev = serial_core_ctrl_device_add(port);
+ if (!new_ctrl_dev) {
+ ret = -ENODEV;
+ goto err_unlock;
+ }
+ ctrl_dev = new_ctrl_dev;
+ }
+
+ /*
+ * Initialize a serial core port device. Tag the port dead to prevent
+ * serial_port_runtime_resume() trying to do anything until port has
+ * been registered. It gets cleared by serial_core_add_one_port().
+ */
+ ret = serial_core_port_device_add(ctrl_dev, port);
+ if (ret)
+ goto err_unregister_ctrl_dev;
+
+ ret = serial_core_add_one_port(drv, port);
+ if (ret)
+ goto err_unregister_port_dev;
+
+ port->flags &= ~UPF_DEAD;
+
+ mutex_unlock(&port_mutex);
+
+ return 0;
+
+err_unregister_port_dev:
+ serial_base_device_remove(port->port_dev);
+
+err_unregister_ctrl_dev:
+ serial_base_device_remove(new_ctrl_dev);
+
+err_unlock:
+ mutex_unlock(&port_mutex);
+
+ return ret;
+}
+
+/*
+ * Removes a serial core port device, and the related serial core controller
+ * device if the last instance.
+ */
+void serial_core_unregister_port(struct uart_driver *drv, struct uart_port *port)
+{
+ struct device *phys_dev = port->dev;
+ struct device *port_dev = port->port_dev;
+ struct device *ctrl_dev = port_dev->parent;
+ int ctrl_id = port->ctrl_id;
+
+ mutex_lock(&port_mutex);
+
+ port->flags |= UPF_DEAD;
+
+ serial_core_remove_one_port(drv, port);
+
+ /* Note that struct uart_port *port is no longer valid at this point */
+ serial_base_device_remove(port_dev);
+
+ /* Drop the serial core controller device if no ports are using it */
+ if (!serial_core_ctrl_find(drv, phys_dev, ctrl_id))
+ serial_base_device_remove(ctrl_dev);
+
+ mutex_unlock(&port_mutex);
+}
+
/**
* uart_handle_dcd_change - handle a change of carrier detect state
* @uport: uart_port structure for the open port
diff --git a/drivers/tty/serial/serial_ctrl.c b/drivers/tty/serial/serial_ctrl.c
new file mode 100644
--- /dev/null
+++ b/drivers/tty/serial/serial_ctrl.c
@@ -0,0 +1,68 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Serial core controller driver
+ *
+ * Copyright (C) 2023 Texas Instruments Incorporated - https://www.ti.com/
+ * Author: Tony Lindgren <[email protected]>
+ *
+ * This driver manages the serial core controller struct device instances.
+ * The serial core controller devices are children of the physical serial
+ * port device.
+ */
+
+#include <linux/device.h>
+#include <linux/module.h>
+#include <linux/pm_runtime.h>
+#include <linux/serial_core.h>
+#include <linux/spinlock.h>
+
+#include "serial_base.h"
+
+static int serial_ctrl_probe(struct device *dev)
+{
+ pm_runtime_enable(dev);
+
+ return 0;
+}
+
+static int serial_ctrl_remove(struct device *dev)
+{
+ pm_runtime_disable(dev);
+
+ return 0;
+}
+
+/*
+ * Serial core controller device init functions. Note that the physical
+ * serial port device driver may not have completed probe at this point.
+ */
+int serial_ctrl_register_port(struct uart_driver *drv, struct uart_port *port)
+{
+ return serial_core_register_port(drv, port);
+}
+
+void serial_ctrl_unregister_port(struct uart_driver *drv, struct uart_port *port)
+{
+ serial_core_unregister_port(drv, port);
+}
+
+static struct device_driver serial_ctrl_driver = {
+ .name = "ctrl",
+ .suppress_bind_attrs = true,
+ .probe = serial_ctrl_probe,
+ .remove = serial_ctrl_remove,
+};
+
+int serial_base_ctrl_init(void)
+{
+ return serial_base_driver_register(&serial_ctrl_driver);
+}
+
+void serial_base_ctrl_exit(void)
+{
+ serial_base_driver_unregister(&serial_ctrl_driver);
+}
+
+MODULE_AUTHOR("Tony Lindgren <[email protected]>");
+MODULE_DESCRIPTION("Serial core controller driver");
+MODULE_LICENSE("GPL");
diff --git a/drivers/tty/serial/serial_port.c b/drivers/tty/serial/serial_port.c
new file mode 100644
--- /dev/null
+++ b/drivers/tty/serial/serial_port.c
@@ -0,0 +1,105 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Serial core port device driver
+ *
+ * Copyright (C) 2023 Texas Instruments Incorporated - https://www.ti.com/
+ * Author: Tony Lindgren <[email protected]>
+ */
+
+#include <linux/device.h>
+#include <linux/module.h>
+#include <linux/pm_runtime.h>
+#include <linux/serial_core.h>
+#include <linux/spinlock.h>
+
+#include "serial_base.h"
+
+#define SERIAL_PORT_AUTOSUSPEND_DELAY_MS 500
+
+/* Only considers pending TX for now. Caller must take care of locking */
+static int __serial_port_busy(struct uart_port *port)
+{
+ return !uart_tx_stopped(port) &&
+ uart_circ_chars_pending(&port->state->xmit);
+}
+
+static int serial_port_runtime_resume(struct device *dev)
+{
+ struct uart_port *port;
+ unsigned long flags;
+
+ port = serial_base_get_port(dev);
+ if (!port || port->flags & UPF_DEAD)
+ goto out;
+
+ /* Flush any pending TX for the port */
+ spin_lock_irqsave(&port->lock, flags);
+ if (__serial_port_busy(port))
+ port->ops->start_tx(port);
+ spin_unlock_irqrestore(&port->lock, flags);
+
+out:
+ pm_runtime_mark_last_busy(dev);
+
+ return 0;
+}
+
+static DEFINE_RUNTIME_DEV_PM_OPS(serial_port_pm, NULL,
+ serial_port_runtime_resume, NULL);
+
+static int serial_port_probe(struct device *dev)
+{
+ pm_runtime_enable(dev);
+ pm_runtime_set_autosuspend_delay(dev, SERIAL_PORT_AUTOSUSPEND_DELAY_MS);
+ pm_runtime_use_autosuspend(dev);
+
+ return 0;
+}
+
+static int serial_port_remove(struct device *dev)
+{
+ pm_runtime_dont_use_autosuspend(dev);
+ pm_runtime_disable(dev);
+
+ return 0;
+}
+
+/*
+ * Serial core port device init functions. Note that the physical serial
+ * port device driver may not have completed probe at this point.
+ */
+int uart_add_one_port(struct uart_driver *drv, struct uart_port *port)
+{
+ return serial_ctrl_register_port(drv, port);
+}
+EXPORT_SYMBOL(uart_add_one_port);
+
+int uart_remove_one_port(struct uart_driver *drv, struct uart_port *port)
+{
+ serial_ctrl_unregister_port(drv, port);
+
+ return 0;
+}
+EXPORT_SYMBOL(uart_remove_one_port);
+
+static struct device_driver serial_port_driver = {
+ .name = "port",
+ .suppress_bind_attrs = true,
+ .probe = serial_port_probe,
+ .remove = serial_port_remove,
+ .pm = pm_ptr(&serial_port_pm),
+};
+
+int serial_base_port_init(void)
+{
+ return serial_base_driver_register(&serial_port_driver);
+}
+
+void serial_base_port_exit(void)
+{
+ serial_base_driver_unregister(&serial_port_driver);
+}
+
+MODULE_AUTHOR("Tony Lindgren <[email protected]>");
+MODULE_DESCRIPTION("Serial controller port driver");
+MODULE_LICENSE("GPL");
diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
--- a/include/linux/serial_core.h
+++ b/include/linux/serial_core.h
@@ -458,6 +458,7 @@ struct uart_port {
struct serial_rs485 *rs485);
int (*iso7816_config)(struct uart_port *,
struct serial_iso7816 *iso7816);
+ int ctrl_id; /* optional serial core controller id */
unsigned int irq; /* irq number */
unsigned long irqflags; /* irq flags */
unsigned int uartclk; /* base uart clock */
@@ -563,7 +564,8 @@ struct uart_port {
unsigned int minor;
resource_size_t mapbase; /* for ioremap */
resource_size_t mapsize;
- struct device *dev; /* parent device */
+ struct device *dev; /* serial port physical parent device */
+ struct device *port_dev; /* serial core port device */
unsigned long sysrq; /* sysrq timeout */
unsigned int sysrq_ch; /* char for sysrq */
--
2.40.1
On Mon, May 08, 2023 at 02:03:35PM +0300, Tony Lindgren wrote:
> We want to enable runtime PM for serial port device drivers in a generic
> way. To do this, we want to have the serial core layer manage the
> registered physical serial controller devices.
>
> To do this, let's set up a struct bus and struct device for the serial
> core controller as suggested by Greg and Jiri. The serial core controller
> devices are children of the physical serial port device. The serial core
> controller device is needed to support multiple different kind of ports
> connected to single physical serial port device.
>
> Let's also set up a struct device for the serial core port. The serial
> core port instances are children of the serial core controller device.
>
> With the serial core port device we can now flush pending TX on the
> runtime PM resume as suggested by Johan.
Sorry, I'm on vacation. But just brief comments below.
In general looks good to me.
...
> -obj-$(CONFIG_SERIAL_CORE) += serial_core.o
> +obj-$(CONFIG_SERIAL_CORE) += serial_base.o
> +serial_base-objs := serial_core.o serial_base_bus.o serial_ctrl.o serial_port.o
'objs' is for user space tools, kernel should use 'y'
...
> +static DEFINE_RUNTIME_DEV_PM_OPS(serial_port_pm, NULL,
> + serial_port_runtime_resume, NULL);
Maybe
static DEFINE_RUNTIME_DEV_PM_OPS(serial_port_pm,
NULL, serial_port_runtime_resume, NULL);
for better logical split?
--
With Best Regards,
Andy Shevchenko
* Andy Shevchenko <[email protected]> [230508 12:11]:
> On Mon, May 08, 2023 at 02:03:35PM +0300, Tony Lindgren wrote:
> > We want to enable runtime PM for serial port device drivers in a generic
> > way. To do this, we want to have the serial core layer manage the
> > registered physical serial controller devices.
> >
> > To do this, let's set up a struct bus and struct device for the serial
> > core controller as suggested by Greg and Jiri. The serial core controller
> > devices are children of the physical serial port device. The serial core
> > controller device is needed to support multiple different kind of ports
> > connected to single physical serial port device.
> >
> > Let's also set up a struct device for the serial core port. The serial
> > core port instances are children of the serial core controller device.
> >
> > With the serial core port device we can now flush pending TX on the
> > runtime PM resume as suggested by Johan.
>
> Sorry, I'm on vacation. But just brief comments below.
> In general looks good to me.
OK have a nice vacation :)
> > -obj-$(CONFIG_SERIAL_CORE) += serial_core.o
> > +obj-$(CONFIG_SERIAL_CORE) += serial_base.o
> > +serial_base-objs := serial_core.o serial_base_bus.o serial_ctrl.o serial_port.o
>
> 'objs' is for user space tools, kernel should use 'y'
Oh OK.
> > +static DEFINE_RUNTIME_DEV_PM_OPS(serial_port_pm, NULL,
> > + serial_port_runtime_resume, NULL);
>
> Maybe
>
> static DEFINE_RUNTIME_DEV_PM_OPS(serial_port_pm,
> NULL, serial_port_runtime_resume, NULL);
>
> for better logical split?
Sure.
Thanks,
Tony
Hi Tony,
kernel test robot noticed the following build warnings:
[auto build test WARNING on tty/tty-testing]
[also build test WARNING on tty/tty-next tty/tty-linus usb/usb-testing usb/usb-next usb/usb-linus linus/master v6.4-rc1 next-20230508]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]
url: https://github.com/intel-lab-lkp/linux/commits/Tony-Lindgren/serial-core-Start-managing-serial-controllers-to-enable-runtime-PM/20230508-190805
base: https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty.git tty-testing
patch link: https://lore.kernel.org/r/20230508110339.38699-1-tony%40atomide.com
patch subject: [PATCH v10 1/1] serial: core: Start managing serial controllers to enable runtime PM
config: x86_64-randconfig-a001-20230508 (https://download.01.org/0day-ci/archive/20230509/[email protected]/config)
compiler: clang version 14.0.6 (https://github.com/llvm/llvm-project f28c006a5895fc0e329fe15fead81e37457cb1d1)
reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# https://github.com/intel-lab-lkp/linux/commit/2f298f9dbe3a1d9550e1f15bb1415aeaf9ce4311
git remote add linux-review https://github.com/intel-lab-lkp/linux
git fetch --no-tags linux-review Tony-Lindgren/serial-core-Start-managing-serial-controllers-to-enable-runtime-PM/20230508-190805
git checkout 2f298f9dbe3a1d9550e1f15bb1415aeaf9ce4311
# save the config file
mkdir build_dir && cp config build_dir/.config
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=x86_64 olddefconfig
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash drivers/tty/serial/
If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <[email protected]>
| Link: https://lore.kernel.org/oe-kbuild-all/[email protected]/
All warnings (new ones prefixed by >>):
>> drivers/tty/serial/serial_base_bus.c:97:13: warning: variable 'id' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
} else if (type == &serial_port_type) {
^~~~~~~~~~~~~~~~~~~~~~~~~
drivers/tty/serial/serial_base_bus.c:102:77: note: uninitialized use occurs here
err = dev_set_name(&sbd->dev, "%s.%s.%d", type->name, dev_name(port->dev), id);
^~
drivers/tty/serial/serial_base_bus.c:97:9: note: remove the 'if' if its condition is always true
} else if (type == &serial_port_type) {
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/tty/serial/serial_base_bus.c:83:13: note: initialize the variable 'id' to silence this warning
int err, id;
^
= 0
1 warning generated.
vim +97 drivers/tty/serial/serial_base_bus.c
77
78 static struct device *serial_base_device_add(struct uart_port *port,
79 struct device *parent_dev,
80 const struct device_type *type)
81 {
82 struct serial_base_device *sbd;
83 int err, id;
84
85 sbd = kzalloc(sizeof(*sbd), GFP_KERNEL);
86 if (!sbd)
87 return NULL;
88
89 device_initialize(&sbd->dev);
90 sbd->dev.type = type;
91 sbd->dev.parent = parent_dev;
92 sbd->dev.bus = &serial_base_bus_type;
93 sbd->dev.release = &serial_base_release;
94
95 if (type == &serial_ctrl_type) {
96 id = port->ctrl_id;
> 97 } else if (type == &serial_port_type) {
98 id = port->line;
99 sbd->port = port;
100 }
101
102 err = dev_set_name(&sbd->dev, "%s.%s.%d", type->name, dev_name(port->dev), id);
103 if (err)
104 goto err_free_dev;
105
106 err = device_add(&sbd->dev);
107 if (err)
108 goto err_put_device;
109
110 return &sbd->dev;
111
112 err_put_device:
113 put_device(&sbd->dev);
114
115 err_free_dev:
116 kfree(sbd);
117
118 return NULL;
119 }
120
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests
* kernel test robot <[email protected]> [230508 23:13]:
> >> drivers/tty/serial/serial_base_bus.c:97:13: warning: variable 'id' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
> } else if (type == &serial_port_type) {
> ^~~~~~~~~~~~~~~~~~~~~~~~~
> drivers/tty/serial/serial_base_bus.c:102:77: note: uninitialized use occurs here
> err = dev_set_name(&sbd->dev, "%s.%s.%d", type->name, dev_name(port->dev), id);
> ^~
> drivers/tty/serial/serial_base_bus.c:97:9: note: remove the 'if' if its condition is always true
> } else if (type == &serial_port_type) {
> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> drivers/tty/serial/serial_base_bus.c:83:13: note: initialize the variable 'id' to silence this warning
> int err, id;
> ^
> = 0
> 1 warning generated.
Thanks I'll just add else goto err_free_dev for unknown types.
Regards,
Tony