Re: [V2, 2/2] media: i2c: Add DW9768 VCM driver

[Tomasz Figa <tfiga@chromium.org>]

Hi Dongchun,

On Thu, Sep 5, 2019 at 4:22 PM <dongchun.zhu@mediatek.com> wrote:
>
> From: Dongchun Zhu <dongchun.zhu@mediatek.com>
>
> This patch adds a V4L2 sub-device driver for DW9768 lens voice coil,
> and provides control to set the desired focus.
>
> The DW9768 is a 10 bit DAC with 100mA output current sink capability
> from Dongwoon, designed for linear control of voice coil motor,
> and controlled via I2C serial interface.
>
> Signed-off-by: Dongchun Zhu <dongchun.zhu@mediatek.com>
> ---
>  MAINTAINERS                |   1 +
>  drivers/media/i2c/Kconfig  |  10 ++
>  drivers/media/i2c/Makefile |   1 +
>  drivers/media/i2c/dw9768.c | 349 +++++++++++++++++++++++++++++++++++++++++++++
>  4 files changed, 361 insertions(+)
>  create mode 100644 drivers/media/i2c/dw9768.c
>

Thanks for v2! Please see my comments inline.

> diff --git a/MAINTAINERS b/MAINTAINERS
> index 192a671..c5c9a0e 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -4976,6 +4976,7 @@ M:        Dongchun Zhu <dongchun.zhu@mediatek.com>
>  L:     linux-media@vger.kernel.org
>  T:     git git://linuxtv.org/media_tree.git
>  S:     Maintained
> +F:     drivers/media/i2c/dw9768.c
>  F:     Documentation/devicetree/bindings/media/i2c/dongwoon,dw9768.txt
>
>  DONGWOON DW9807 LENS VOICE COIL DRIVER
> diff --git a/drivers/media/i2c/Kconfig b/drivers/media/i2c/Kconfig
> index 79ce9ec..dfb665c 100644
> --- a/drivers/media/i2c/Kconfig
> +++ b/drivers/media/i2c/Kconfig
> @@ -1016,6 +1016,16 @@ config VIDEO_DW9714
>           capability. This is designed for linear control of
>           voice coil motors, controlled via I2C serial interface.
>
> +config VIDEO_DW9768
> +       tristate "DW9768 lens voice coil support"
> +       depends on I2C && VIDEO_V4L2 && MEDIA_CONTROLLER
> +       depends on VIDEO_V4L2_SUBDEV_API
> +       help
> +         This is a driver for the DW9768 camera lens voice coil.
> +         DW9768 is a 10 bit DAC with 100mA output current sink
> +         capability. This is designed for linear control of
> +         voice coil motors, controlled via I2C serial interface.
> +
>  config VIDEO_DW9807_VCM
>         tristate "DW9807 lens voice coil support"
>         depends on I2C && VIDEO_V4L2 && MEDIA_CONTROLLER
> diff --git a/drivers/media/i2c/Makefile b/drivers/media/i2c/Makefile
> index fd4ea86..2561239 100644
> --- a/drivers/media/i2c/Makefile
> +++ b/drivers/media/i2c/Makefile
> @@ -24,6 +24,7 @@ obj-$(CONFIG_VIDEO_SAA6752HS) += saa6752hs.o
>  obj-$(CONFIG_VIDEO_AD5820)  += ad5820.o
>  obj-$(CONFIG_VIDEO_AK7375)  += ak7375.o
>  obj-$(CONFIG_VIDEO_DW9714)  += dw9714.o
> +obj-$(CONFIG_VIDEO_DW9768)  += dw9768.o
>  obj-$(CONFIG_VIDEO_DW9807_VCM)  += dw9807-vcm.o
>  obj-$(CONFIG_VIDEO_ADV7170) += adv7170.o
>  obj-$(CONFIG_VIDEO_ADV7175) += adv7175.o
> diff --git a/drivers/media/i2c/dw9768.c b/drivers/media/i2c/dw9768.c
> new file mode 100644
> index 0000000..66d1712
> --- /dev/null
> +++ b/drivers/media/i2c/dw9768.c
> @@ -0,0 +1,349 @@
> +// SPDX-License-Identifier: GPL-2.0
> +// Copyright (c) 2019 MediaTek Inc.
> +
> +#include <linux/delay.h>
> +#include <linux/i2c.h>
> +#include <linux/module.h>
> +#include <linux/regulator/consumer.h>
> +#include <linux/pm_runtime.h>
> +#include <media/v4l2-ctrls.h>
> +#include <media/v4l2-device.h>
> +#include <media/v4l2-subdev.h>
> +
> +#define DW9768_NAME                            "dw9768"
> +#define DW9768_MAX_FOCUS_POS                   1023
> +/*
> + * This sets the minimum granularity for the focus positions.
> + * A value of 1 gives maximum accuracy for a desired focus position
> + */
> +#define DW9768_FOCUS_STEPS                     1
> +/*
> + * DW9768 separates two registers to control the VCM position.
> + * One for MSB value, another is LSB value.
> + */
> +#define DW9768_REG_MASK_MSB                    0x03
> +#define DW9768_REG_MASK_LSB                    0xff
> +#define DW9768_SET_POSITION_ADDR                0x03
> +
> +#define DW9768_CMD_DELAY                       0xff
> +#define DW9768_CTRL_DELAY_US                   5000
> +
> +#define DW9768_DAC_SHIFT                       8
> +
> +/* dw9768 device structure */
> +struct dw9768 {
> +       struct v4l2_ctrl_handler ctrls;
> +       struct v4l2_subdev sd;
> +       struct regulator *vin;
> +       struct regulator *vdd;
> +};
> +
> +static inline struct dw9768 *to_dw9768_vcm(struct v4l2_ctrl *ctrl)
> +{
> +       return container_of(ctrl->handler, struct dw9768, ctrls);
> +}
> +
> +static inline struct dw9768 *sd_to_dw9768_vcm(struct v4l2_subdev *subdev)
> +{
> +       return container_of(subdev, struct dw9768, sd);
> +}
> +
> +struct regval_list {
> +       unsigned char reg_num;
> +       unsigned char value;
> +};
> +
> +static struct regval_list dw9768_init_regs[] = {
> +       {0x02, 0x02},
> +       {DW9768_CMD_DELAY, DW9768_CMD_DELAY},
> +       {0x06, 0x41},
> +       {0x07, 0x39},
> +       {DW9768_CMD_DELAY, DW9768_CMD_DELAY},
> +};
> +
> +static struct regval_list dw9768_release_regs[] = {
> +       {0x02, 0x00},
> +       {DW9768_CMD_DELAY, DW9768_CMD_DELAY},
> +       {0x01, 0x00},
> +       {DW9768_CMD_DELAY, DW9768_CMD_DELAY},
> +};
> +
> +static int dw9768_write_smbus(struct dw9768 *dw9768, unsigned char reg,
> +                             unsigned char value)
> +{
> +       struct i2c_client *client = v4l2_get_subdevdata(&dw9768->sd);
> +       int ret;
> +
> +       if (reg == DW9768_CMD_DELAY  && value == DW9768_CMD_DELAY)

Do we really need both to be set to this command?

> +               usleep_range(DW9768_CTRL_DELAY_US,
> +                            DW9768_CTRL_DELAY_US + 100);
> +       else
> +               ret = i2c_smbus_write_byte_data(client, reg, value);
> +       return ret;
> +}

Is there any reason to have this as a separate function and not just
implemented inside the function below?

> +
> +static int dw9768_write_array(struct dw9768 *dw9768, struct regval_list *vals,
> +                             u32 len)
> +{
> +       unsigned int i;
> +       int ret;
> +
> +       for (i = 0; i < len; i++) {
> +               ret = dw9768_write_smbus(dw9768, vals->reg_num, vals->value);
> +               if (ret < 0)
> +                       return ret;
> +       }
> +       return 0;
> +}
> +
> +static int dw9768_set_position(struct dw9768 *dw9768, u16 val)
> +{
> +       struct i2c_client *client = v4l2_get_subdevdata(&dw9768->sd);
> +       u8 addr[2];
> +
> +       addr[0] = (val >> DW9768_DAC_SHIFT) & DW9768_REG_MASK_MSB;
> +       addr[1] = val & DW9768_REG_MASK_LSB;
> +
> +       return i2c_smbus_write_block_data(client, DW9768_SET_POSITION_ADDR,
> +                                         ARRAY_SIZE(addr), addr);
> +}
> +
> +static int dw9768_release(struct dw9768 *dw9768)
> +{
> +       return dw9768_write_array(dw9768, dw9768_release_regs,
> +                                 ARRAY_SIZE(dw9768_release_regs));
> +}
> +
> +static int dw9768_init(struct dw9768 *dw9768)
> +{
> +       return dw9768_write_array(dw9768, dw9768_init_regs,
> +                                 ARRAY_SIZE(dw9768_init_regs));
> +}

Given that the 2 functions above are just called from 1 place,
wouldn't it make sense to just call dw9768_write_array() directly from
there?

> +
> +/* Power handling */
> +static int dw9768_power_off(struct dw9768 *dw9768)
> +{
> +       struct i2c_client *client = v4l2_get_subdevdata(&dw9768->sd);
> +       int ret;
> +
> +       ret = dw9768_release(dw9768);
> +       if (ret)
> +               dev_err(&client->dev, "dw9768 release failed!\n");
> +
> +       ret = regulator_disable(dw9768->vin);
> +       if (ret)
> +               return ret;
> +
> +       return regulator_disable(dw9768->vdd);
> +}
> +
> +static int dw9768_power_on(struct dw9768 *dw9768)
> +{
> +       int ret;
> +
> +       ret = regulator_enable(dw9768->vin);
> +       if (ret < 0)
> +               return ret;
> +
> +       ret = regulator_enable(dw9768->vdd);
> +       if (ret < 0)
> +               return ret;
> +
> +       ret = dw9768_init(dw9768);
> +       if (ret < 0)
> +               goto fail;
> +
> +       return 0;
> +
> +fail:
> +       regulator_disable(dw9768->vin);
> +       regulator_disable(dw9768->vdd);
> +
> +       return ret;
> +}
> +
> +static int dw9768_set_ctrl(struct v4l2_ctrl *ctrl)
> +{
> +       struct dw9768 *dw9768 = to_dw9768_vcm(ctrl);
> +
> +       if (ctrl->id == V4L2_CID_FOCUS_ABSOLUTE)
> +               return dw9768_set_position(dw9768, ctrl->val);
> +
> +       return 0;
> +}
> +
> +static const struct v4l2_ctrl_ops dw9768_vcm_ctrl_ops = {
> +       .s_ctrl = dw9768_set_ctrl,
> +};
> +
> +static int dw9768_open(struct v4l2_subdev *sd, struct v4l2_subdev_fh *fh)
> +{
> +       int ret;
> +
> +       ret = pm_runtime_get_sync(sd->dev);
> +       if (ret < 0) {
> +               pm_runtime_put_noidle(sd->dev);
> +               return ret;
> +       }
> +
> +       return 0;
> +}
> +
> +static int dw9768_close(struct v4l2_subdev *sd, struct v4l2_subdev_fh *fh)
> +{
> +       pm_runtime_put(sd->dev);
> +
> +       return 0;
> +}
> +
> +static const struct v4l2_subdev_internal_ops dw9768_int_ops = {
> +       .open = dw9768_open,
> +       .close = dw9768_close,
> +};
> +
> +static const struct v4l2_subdev_ops dw9768_ops = { };
> +
> +static void dw9768_subdev_cleanup(struct dw9768 *dw9768)
> +{
> +       v4l2_async_unregister_subdev(&dw9768->sd);
> +       v4l2_ctrl_handler_free(&dw9768->ctrls);
> +       media_entity_cleanup(&dw9768->sd.entity);
> +}
> +
> +static int dw9768_init_controls(struct dw9768 *dw9768)
> +{
> +       struct v4l2_ctrl_handler *hdl = &dw9768->ctrls;
> +       const struct v4l2_ctrl_ops *ops = &dw9768_vcm_ctrl_ops;
> +
> +       v4l2_ctrl_handler_init(hdl, 1);
> +
> +       v4l2_ctrl_new_std(hdl, ops, V4L2_CID_FOCUS_ABSOLUTE,
> +                         0, DW9768_MAX_FOCUS_POS, DW9768_FOCUS_STEPS, 0);
> +
> +       if (hdl->error)
> +               return hdl->error;
> +
> +       dw9768->sd.ctrl_handler = hdl;
> +
> +       return 0;
> +}
> +
> +static int dw9768_probe(struct i2c_client *client)
> +{
> +       struct device *dev = &client->dev;
> +       struct dw9768 *dw9768;
> +       int ret;
> +
> +       dw9768 = devm_kzalloc(dev, sizeof(*dw9768), GFP_KERNEL);
> +       if (!dw9768)
> +               return -ENOMEM;
> +
> +       dw9768->vin = devm_regulator_get(dev, "vin");
> +       if (IS_ERR(dw9768->vin)) {
> +               ret = PTR_ERR(dw9768->vin);
> +               if (ret != -EPROBE_DEFER)
> +                       dev_err(dev, "cannot get vin regulator\n");
> +               return ret;
> +       }
> +
> +       dw9768->vdd = devm_regulator_get(dev, "vdd");
> +       if (IS_ERR(dw9768->vdd)) {
> +               ret = PTR_ERR(dw9768->vdd);
> +               if (ret != -EPROBE_DEFER)
> +                       dev_err(dev, "cannot get vdd regulator\n");
> +               return ret;
> +       }

Any reason not to use the regulator bulk API, as already done in the
fixup patch I shared with you earlier [1]?

[1] https://chromium-review.googlesource.com/c/chromiumos/third_party/kernel/+/1757579

Best regards,
Tomasz