[PATCH 2/3] console: Add simplified 'serdev' framework from Linux kernel
Andrey Smirnov
andrew.smirnov at gmail.com
Mon Mar 26 06:09:14 PDT 2018
Port 'serdev' UART-slave deivce framework found in recent Linux
kernels (post 4.13) in order to be able to port 'serdev' slave drivers
from Linux.
Signed-off-by: Andrey Smirnov <andrew.smirnov at gmail.com>
---
common/Kconfig | 6 ++++
common/Makefile | 1 +
common/console.c | 24 +++++++++++++--
common/serdev.c | 87 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
include/console.h | 27 +++++++++++++++++
include/serdev.h | 36 +++++++++++++++++++++++
6 files changed, 178 insertions(+), 3 deletions(-)
create mode 100644 common/serdev.c
create mode 100644 include/serdev.h
diff --git a/common/Kconfig b/common/Kconfig
index 81cf72a95..601bc95a4 100644
--- a/common/Kconfig
+++ b/common/Kconfig
@@ -712,6 +712,12 @@ config CONSOLE_NONE
endchoice
+config SERIAL_DEV_BUS
+ bool "Serial device bus"
+ depends on CONSOLE_FULL
+ help
+ Core support for devices connected via a serial port.
+
choice
prompt "Console activation strategy"
depends on CONSOLE_FULL
diff --git a/common/Makefile b/common/Makefile
index a9abcd1bc..c945dd78e 100644
--- a/common/Makefile
+++ b/common/Makefile
@@ -61,6 +61,7 @@ obj-$(CONFIG_FIRMWARE) += firmware.o
obj-$(CONFIG_UBIFORMAT) += ubiformat.o
obj-$(CONFIG_BAREBOX_UPDATE_IMX_NAND_FCB) += imx-bbu-nand-fcb.o
obj-$(CONFIG_BOOT) += boot.o
+obj-$(CONFIG_SERIAL_DEV_BUS) += serdev.o
ifdef CONFIG_PASSWORD
diff --git a/common/console.c b/common/console.c
index f4c799fa5..13b1360b5 100644
--- a/common/console.c
+++ b/common/console.c
@@ -305,10 +305,11 @@ static ssize_t fops_write(struct cdev* dev, const void* buf, size_t count,
int console_register(struct console_device *newcdev)
{
+ struct device_node *serdev_node = console_is_serdev_node(newcdev);
struct device_d *dev = &newcdev->class_dev;
int activate = 0, ret;
- if (initialized == CONSOLE_UNINITIALIZED)
+ if (!serdev_node && initialized == CONSOLE_UNINITIALIZED)
console_init_early();
if (newcdev->devname) {
@@ -323,6 +324,17 @@ int console_register(struct console_device *newcdev)
dev->parent = newcdev->dev;
platform_device_register(dev);
+ newcdev->open_count = 0;
+
+ /*
+ * If our console deive is a serdev, we skip the creation of
+ * corresponding entry in /dev as well as registration in
+ * console_list and just go straigh to populating child
+ * devices.
+ */
+ if (serdev_node)
+ return of_platform_populate(serdev_node, NULL, dev);
+
if (newcdev->setbrg) {
ret = newcdev->setbrg(newcdev, CONFIG_BAUDRATE);
if (ret)
@@ -335,8 +347,6 @@ int console_register(struct console_device *newcdev)
if (newcdev->putc && !newcdev->puts)
newcdev->puts = __console_puts;
- newcdev->open_count = 0;
-
dev_add_param_string(dev, "active", console_active_set, console_active_get,
&newcdev->active_string, newcdev);
@@ -386,6 +396,14 @@ int console_unregister(struct console_device *cdev)
struct device_d *dev = &cdev->class_dev;
int status;
+ /*
+ * We don't do any sophisticated serdev device de-population
+ * and instead claim this console busy, preventing its
+ * de-initialization, 'till the very end of our execution.
+ */
+ if (console_is_serdev_node(cdev))
+ return -EBUSY;
+
devfs_remove(&cdev->devfs);
list_del(&cdev->list);
diff --git a/common/serdev.c b/common/serdev.c
new file mode 100644
index 000000000..58985c4b1
--- /dev/null
+++ b/common/serdev.c
@@ -0,0 +1,87 @@
+
+#include <common.h>
+#include <serdev.h>
+
+static void serdev_device_poller(void *context)
+{
+ struct serdev_device *serdev = context;
+ struct console_device *cdev = to_console_device(serdev);
+ unsigned char *buf = serdev->buf;
+ int ret, len;
+
+ /*
+ * Since this callback is a part of poller infrastructure we
+ * want to use _non_interruptible version of the function
+ * below to prevent recursion from happening (regular
+ * console_drain will call is_timeout, which might end up
+ * calling this function again).
+ */
+ len = console_drain_non_interruptible(cdev, serdev->fifo, buf,
+ PAGE_SIZE,
+ serdev->polling_window);
+ while (len > 0) {
+ ret = serdev->receive_buf(serdev, buf, len);
+ len -= ret;
+ buf += ret;
+ }
+
+ /*
+ * Re-schedule ourselves in 'serdev->polling_interval'
+ * nanoseconds
+ */
+ poller_call_async(&serdev->poller,
+ serdev->polling_interval,
+ serdev_device_poller,
+ serdev);
+}
+
+int serdev_device_open(struct serdev_device *serdev)
+{
+ struct console_device *cdev = to_console_device(serdev);
+ int ret;
+
+ if (!cdev->putc || !cdev->getc)
+ return -EINVAL;
+
+ if (!serdev->polling_window || !serdev->polling_interval)
+ return -EINVAL;
+
+ serdev->buf = xzalloc(PAGE_SIZE);
+ serdev->fifo = kfifo_alloc(PAGE_SIZE);
+ if (!serdev->fifo)
+ return -ENOMEM;
+
+ ret = poller_async_register(&serdev->poller);
+ if (ret)
+ return ret;
+
+ return console_open(cdev);
+}
+
+unsigned int serdev_device_set_baudrate(struct serdev_device *serdev,
+ unsigned int speed)
+{
+ struct console_device *cdev = to_console_device(serdev);
+
+ if (console_set_baudrate(cdev, speed) < 0)
+ return 0;
+
+ return console_get_baudrate(cdev);
+}
+
+int serdev_device_write(struct serdev_device *serdev, const unsigned char *buf,
+ size_t count, unsigned long timeout)
+{
+ struct console_device *cdev = to_console_device(serdev);
+
+ while (count--)
+ cdev->putc(cdev, *buf++);
+ /*
+ * Poll Rx once right after we just send some data in case our
+ * serdev device implements command/response type of a
+ * protocol and we need to start draining input as soon as
+ * possible.
+ */
+ serdev_device_poller(serdev);
+ return 0;
+}
diff --git a/include/console.h b/include/console.h
index 4aa4c8f9e..14f00fa1e 100644
--- a/include/console.h
+++ b/include/console.h
@@ -23,6 +23,7 @@
#include <param.h>
#include <linux/list.h>
#include <driver.h>
+#include <serdev.h>
#include <clock.h>
#define CONSOLE_STDIN (1 << 0)
@@ -65,8 +66,34 @@ struct console_device {
struct cdev devfs;
struct file_operations fops;
+
+ struct serdev_device serdev;
};
+static inline struct serdev_device *to_serdev_device(struct device_d *d)
+{
+ struct console_device *cdev =
+ container_of(d, struct console_device, class_dev);
+ return &cdev->serdev;
+}
+
+static inline struct console_device *
+to_console_device(struct serdev_device *serdev)
+{
+ return container_of(serdev, struct console_device, serdev);
+}
+
+static inline struct device_node *
+console_is_serdev_node(struct console_device *cdev)
+{
+ struct device_d *dev = cdev->dev;
+ if (dev && dev->device_node &&
+ of_get_child_count(dev->device_node))
+ return dev->device_node;
+
+ return NULL;
+}
+
int console_register(struct console_device *cdev);
int console_unregister(struct console_device *cdev);
diff --git a/include/serdev.h b/include/serdev.h
new file mode 100644
index 000000000..efc735fed
--- /dev/null
+++ b/include/serdev.h
@@ -0,0 +1,36 @@
+#ifndef _SERDEV_H_
+#define _SERDEV_H_
+
+#include <driver.h>
+#include <poller.h>
+#include <kfifo.h>
+
+/**
+ * struct serdev_device - Basic representation of an serdev device
+ *
+ * @dev: Corresponding device
+ * @fifo: Circular buffer used for console draining
+ * @buf: Buffer used to pass Rx data to consumers
+ * @poller Async poller used to poll this serdev
+ * @polling_interval: Async poller periodicity
+ * @polling_window: Duration of a single busy loop poll
+ * @receive_buf: Function called with data received from device;
+ * returns number of bytes accepted;
+ */
+struct serdev_device {
+ struct device_d *dev;
+ struct kfifo *fifo;
+ unsigned char *buf;
+ struct poller_async poller;
+ uint64_t polling_interval;
+ uint64_t polling_window;
+
+ int (*receive_buf)(struct serdev_device *, const unsigned char *,
+ size_t);
+};
+
+int serdev_device_open(struct serdev_device *);
+unsigned int serdev_device_set_baudrate(struct serdev_device *, unsigned int);
+int serdev_device_write(struct serdev_device *, const unsigned char *,
+ size_t, unsigned long);
+#endif
--
2.14.3
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