Re: [PATCH] [media] rc: ir-spi: add support for IR LEDs connected with SPI
From: Rob Herring
Date: Tue Jul 05 2016 - 10:22:20 EST
On Fri, Jul 01, 2016 at 05:33:42PM +0900, Andi Shyti wrote:
> The ir-spi is a simple device driver which supports the
> connection between an IR LED and the MOSI line of an SPI device.
Please split the binding from the driver.
> The driver, indeed, uses the SPI framework to stream the raw data
> provided by userspace through a character device. The chardev is
> handled by the LIRC framework and its functionality basically
> provides:
>
> - raw write: data to be sent to the SPI and then streamed to the
> MOSI line;
> - set frequency: sets the frequency whith which the data should
> be sent;
> - set length: sets the data length. This information is
> optional, if the length is set, then userspace should send raw
> data only with that length; while if the length is set to '0',
> then the driver will figure out himself the length of the data
> based on the length of the data written on the character
> device.
> The latter is not recommended, though, as the driver, at
> any write, allocates and deallocates a buffer where the data
> from userspace are stored.
>
> The driver provides three feedback commands:
>
> - get length: reads the length set and (as mentioned), if the
> length is '0' it will be calculated at any write
> - get frequency: the driver reports the frequency. If userpace
> doesn't set the frequency, the driver will use a default value
> of 38000Hz.
>
> The character device is created under /dev/lircX name, where X is
> and ID assigned by the LIRC framework.
>
> Example of usage:
>
> int fd, ret;
> ssize_t n;
> uint32_t val = 0;
>
> fd = open("/dev/lirc0", O_RDWR);
> if (fd < 0) {
> fprintf(stderr, "unable to open the device\n");
> return -1;
> }
>
> /* ioctl set frequency and length parameters */
> val = 6430;
> ret = ioctl(fd, LIRC_SET_LENGTH, &val);
> if (ret < 0)
> fprintf(stderr, "LIRC_SET_LENGTH failed\n");
> val = 608000;
> ret = ioctl(fd, LIRC_SET_FREQUENCY, &val);
> if (ret < 0)
> fprintf(stderr, "LIRC_SET_FREQUENCY failed\n");
>
> /* read back length and frequency parameters */
> ret = ioctl(fd, LIRC_GET_LENGTH, &val);
> if (ret < 0)
> fprintf(stderr, "LIRC_GET_LENGTH failed\n");
> else
> fprintf(stdout, "legnth = %u\n", val);
>
> ret = ioctl(fd, LIRC_GET_FREQUENCY, &val);
> if (ret < 0)
> fprintf(stderr, "LIRC_GET_FREQUENCY failed\n");
> else
> fprintf(stdout, "frequency = %u\n", val);
>
> /* write data to device */
> n = write(fd, b, 6430);
> if (n < 0) {
> fprintf(stderr, "unable to write to the device\n");
> ret = -1;
> } else if (n != 6430) {
> fprintf(stderr, "failed to write everything, wrote %ld instead\n", n);
> ret = -1;
> } else {
> fprintf(stdout, "written all the %ld data\n", n);
> }
>
> close(fd);
>
> The driver supports multi task access, but all the processes
> which hold the driver should use the same length and frequency
> parameters.
>
> Change-Id: I323d7dd4a56d6dcf48f2c695293822eb04bdb85f
> Signed-off-by: Andi Shyti <andi.shyti@xxxxxxxxxxx>
> ---
> Documentation/devicetree/bindings/media/spi-ir.txt | 24 ++
> drivers/media/rc/Kconfig | 9 +
> drivers/media/rc/Makefile | 1 +
> drivers/media/rc/ir-spi.c | 301 +++++++++++++++++++++
> 4 files changed, 335 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/media/spi-ir.txt
> create mode 100644 drivers/media/rc/ir-spi.c
>
> diff --git a/Documentation/devicetree/bindings/media/spi-ir.txt b/Documentation/devicetree/bindings/media/spi-ir.txt
> new file mode 100644
> index 0000000..2232d92
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/media/spi-ir.txt
> @@ -0,0 +1,24 @@
> +Device tree bindings for IR LED connected through SPI bus which is used as
> +remote controller.
Do said devices have part numbers? Seems kind of generic and I've never
seen such device.
> +The IR LED switch is connected to the MOSI line of the SPI device and the data
> +are delivered thourgh that.
> +
> +Required properties:
> + - compatible: should be "ir-spi"
> +
> +Optional properties:
> + - irled,switch: specifies the gpio switch which enables the irled
Just "switch-gpios"
> +
> +Example:
> +
> + irled@0 {
> + compatible = "ir-spi";
> + reg = <0x0>;
> + spi-max-frequency = <5000000>;
> + irled,switch = <&gpr3 3 0>;
> +
> + controller-data {
This is part of the controller binding? Omit that from the example.
> + samsung,spi-feedback-delay = <0>;
> + };
> + };