diff options
Diffstat (limited to 'common/serdev.c')
| -rw-r--r-- | common/serdev.c | 208 |
1 files changed, 208 insertions, 0 deletions
diff --git a/common/serdev.c b/common/serdev.c new file mode 100644 index 0000000000..4a6dbefe61 --- /dev/null +++ b/common/serdev.c @@ -0,0 +1,208 @@ + +#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; + } + + if (serdev->polling_interval) { + /* + * Re-schedule ourselves in 'serdev->polling_interval' + * nanoseconds + */ + poller_call_async(&serdev->poller, + serdev->polling_interval, + serdev_device_poller, + serdev); + } else { + poller_async_cancel(&serdev->poller); + } +} + +static int serdev_device_set_polling_interval(struct param_d *param, void *serdev) +{ + /* + * We execute poller ever time polling_interval changes to get + * any unprocessed immediate Rx data as well as to propagate + * polling_interval chagnes to outstanging async pollers. + */ + serdev_device_poller(serdev); + return 0; +} + +int serdev_device_open(struct serdev_device *serdev) +{ + struct console_device *cdev = to_console_device(serdev); + struct param_d *p; + int ret; + + if (!cdev->putc || !cdev->getc) + return -EINVAL; + + if (!serdev->polling_window) + 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; + + ret = console_open(cdev); + if (ret) + return ret; + + p = dev_add_param_uint64(serdev->dev, "polling_interval", + serdev_device_set_polling_interval, NULL, + &serdev->polling_interval, "%llu", serdev); + if (IS_ERR(p)) + return PTR_ERR(p); + + return 0; +} + +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; +} + +/* + * NOTE: Code below is given primarily as an example of serdev API + * usage. It may or may not be as useful or work as well as the + * functions above. + */ + +struct serdev_device_reader { + unsigned char *buf; + size_t len; + size_t capacity; +}; + +static int serdev_device_reader_receive_buf(struct serdev_device *serdev, + const unsigned char *buf, + size_t size) +{ + struct device_d *dev = serdev->dev; + struct serdev_device_reader *r = dev->priv; + const size_t room = min(r->capacity - r->len, size); + + memcpy(r->buf + r->len, buf, room); + r->len += room; + /* + * It's important we return 'size' even if we didn't trully + * consume all of the data, since otherwise serdev will keep + * re-executing us until we do. Given the logic above that + * would mean infinite loop. + */ + return size; +} + +/** + * serdev_device_reader_open - Open a reader serdev device + * + * @serdev: Underlying serdev device + * @capacity: Storage capacity of the reader + * + * This function is inteded for creating of reader serdev devices that + * can be used in conjunction with serdev_device_read() to perform + * trivial fixed length reads from a serdev device. + */ +int serdev_device_reader_open(struct serdev_device *serdev, size_t capacity) +{ + struct serdev_device_reader *r; + + if (serdev->receive_buf) + return -EINVAL; + + r = xzalloc(sizeof(*r)); + r->capacity = capacity; + r->buf = xzalloc(capacity); + + serdev->receive_buf = serdev_device_reader_receive_buf; + serdev->dev->priv = r; + + return 0; +} + +/** + * serdev_device_read - Read data from serdev device + * + * @serdev: Serdev device to read from (must be a serdev reader) + * @buf: Buffer to read data into + * @count: Number of bytes to read + * @timeout: Read operation timeout + * + */ +int serdev_device_read(struct serdev_device *serdev, unsigned char *buf, + size_t count, unsigned long timeout) +{ + struct device_d *dev = serdev->dev; + struct serdev_device_reader *r = dev->priv; + int ret; + + uint64_t start = get_time_ns(); + + if (serdev->receive_buf != serdev_device_reader_receive_buf) + return -EINVAL; + + /* + * is_timeout will implicitly poll serdev via poller + * infrastructure + */ + while (r->len < count) { + if (is_timeout(start, timeout)) + return -ETIMEDOUT; + } + + memcpy(buf, r->buf, count); + ret = (r->len == count) ? 0 : -EMSGSIZE; + r->len = 0; + + return ret; +} |