Hi Mita-san,
On Fri, Apr 27, 2018 at 01:13:32AM +0900, Akinobu Mita wrote:
> (This patch is in prototype stage)
>
> This adds SCCB helper functions (sccb_read_byte and sccb_write_byte) that
> are intended to be used by some of Omnivision sensor drivers.
>
> The ov772x driver is going to use these functions in order to make it work
> with most i2c controllers.
>
> As the ov772x device doesn't support repeated starts, this driver currently
> requires I2C_FUNC_PROTOCOL_MANGLING that is not supported by many i2c
> controller drivers.
>
> With the sccb_read_byte() that issues two separated requests in order to
> avoid repeated start, the driver doesn't require I2C_FUNC_PROTOCOL_MANGLING.
>
> Cc: Wolfram Sang <wsa@xxxxxxxxxxxxx>
> Cc: Jacopo Mondi <jacopo+renesas@xxxxxxxxxx>
> Cc: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
> Cc: Hans Verkuil <hans.verkuil@xxxxxxxxx>
> Cc: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx>
> Cc: Mauro Carvalho Chehab <mchehab@xxxxxxxxxxxxxxxx>
> Signed-off-by: Akinobu Mita <akinobu.mita@xxxxxxxxx>
> ---
> drivers/media/i2c/Kconfig | 4 ++++
> drivers/media/i2c/Makefile | 1 +
> drivers/media/i2c/sccb.c | 35 +++++++++++++++++++++++++++++++++++
> drivers/media/i2c/sccb.h | 14 ++++++++++++++
> 4 files changed, 54 insertions(+)
> create mode 100644 drivers/media/i2c/sccb.c
> create mode 100644 drivers/media/i2c/sccb.h
>
> diff --git a/drivers/media/i2c/Kconfig b/drivers/media/i2c/Kconfig
> index 541f0d28..19e5601 100644
> --- a/drivers/media/i2c/Kconfig
> +++ b/drivers/media/i2c/Kconfig
> @@ -569,6 +569,9 @@ config VIDEO_THS8200
>
> comment "Camera sensor devices"
>
> +config SCCB
> + bool
Tristate? This effectively depends on I²C but I²C is tristate...
> +
> config VIDEO_APTINA_PLL
> tristate
>
> @@ -692,6 +695,7 @@ config VIDEO_OV772X
> tristate "OmniVision OV772x sensor support"
> depends on I2C && VIDEO_V4L2
> depends on MEDIA_CAMERA_SUPPORT
> + select SCCB
> ---help---
> This is a Video4Linux2 sensor-level driver for the OmniVision
> OV772x camera.
> diff --git a/drivers/media/i2c/Makefile b/drivers/media/i2c/Makefile
> index ea34aee..82fbd78 100644
> --- a/drivers/media/i2c/Makefile
> +++ b/drivers/media/i2c/Makefile
> @@ -62,6 +62,7 @@ obj-$(CONFIG_VIDEO_VP27SMPX) += vp27smpx.o
> obj-$(CONFIG_VIDEO_SONY_BTF_MPX) += sony-btf-mpx.o
> obj-$(CONFIG_VIDEO_UPD64031A) += upd64031a.o
> obj-$(CONFIG_VIDEO_UPD64083) += upd64083.o
> +obj-$(CONFIG_SCCB) += sccb.o
> obj-$(CONFIG_VIDEO_OV2640) += ov2640.o
> obj-$(CONFIG_VIDEO_OV2685) += ov2685.o
> obj-$(CONFIG_VIDEO_OV5640) += ov5640.o
> diff --git a/drivers/media/i2c/sccb.c b/drivers/media/i2c/sccb.c
> new file mode 100644
> index 0000000..80a3fb7
> --- /dev/null
> +++ b/drivers/media/i2c/sccb.c
> @@ -0,0 +1,35 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +#include <linux/i2c.h>
> +
> +int sccb_read_byte(struct i2c_client *client, u8 addr)
> +{
> + int ret;
> + u8 val;
> +
> + /* Issue two separated requests in order to avoid repeated start */
> +
> + ret = i2c_master_send(client, &addr, 1);
> + if (ret < 0)
> + return ret;
> +
> + ret = i2c_master_recv(client, &val, 1);
> + if (ret < 0)
> + return ret;
> +
> + return val;
> +}
> +EXPORT_SYMBOL_GPL(sccb_read_byte);
> +
> +int sccb_write_byte(struct i2c_client *client, u8 addr, u8 data)
> +{
> + int ret;
> + unsigned char msgbuf[] = { addr, data };
> +
> + ret = i2c_master_send(client, msgbuf, 2);
> + if (ret < 0)
> + return ret;
> +
> + return 0;
> +}
> +EXPORT_SYMBOL_GPL(sccb_write_byte);
Please add MODULE_* macros... follows from tristate option.
> diff --git a/drivers/media/i2c/sccb.h b/drivers/media/i2c/sccb.h
> new file mode 100644
> index 0000000..68da0e9
> --- /dev/null
> +++ b/drivers/media/i2c/sccb.h
> @@ -0,0 +1,14 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * SCCB helper functions
> + */
> +
> +#ifndef __SCCB_H__
> +#define __SCCB_H__
> +
> +#include <linux/i2c.h>
struct i2c_client;
is enough; no need to include the whole header here.
> +
> +int sccb_read_byte(struct i2c_client *client, u8 addr);
> +int sccb_write_byte(struct i2c_client *client, u8 addr, u8 data);
> +
> +#endif /* __SCCB_H__ */
--
Kind regards,
Sakari Ailus
sakari.ailus@xxxxxxxxxxxxxxx
