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    Subject[PATCH v8 1/3] cdx: add support for bus mastering
    Date
    Introduce cdx_set_master() and cdx_clear_master() APIs to support
    enable and disable of bus mastering. Drivers need to use these APIs to
    enable/disable DMAs from the CDX devices.

    Signed-off-by: Nipun Gupta <nipun.gupta@amd.com>
    Reviewed-by: Pieter Jansen van Vuuren <pieter.jansen-van-vuuren@amd.com>
    ---

    Changes v7->v8:
    - Fix a comment in cdx_mcdi_ctrl_flag_set()

    Changes v6->v7:
    - None

    Changes v5->v6:
    - change cdx_clear_master() to int return type

    Changes v4->v5:
    - No change in this patch, patch 2/3 and patch 3/3 are updated

    Changes v3->v4:
    - Added user of the Bus master enable and disable APIs in patch 2/2.
    There is no change in this patch.

    Changes v2->v3:
    - Changed return value from EOPNOTSUPP to -EOPNOTSUPP in
    cdx_set_master()

    Changes v1->v2:
    - Replace bme with bus_master_enable
    - Added check for dev_configure API callback
    - remove un-necessary error prints
    - changed conditional to if-else
    - updated commit message to use 72 columns

    drivers/cdx/cdx.c | 32 ++++++++++++++
    drivers/cdx/controller/cdx_controller.c | 4 ++
    drivers/cdx/controller/mcdi_functions.c | 58 +++++++++++++++++++++++++
    drivers/cdx/controller/mcdi_functions.h | 13 ++++++
    include/linux/cdx/cdx_bus.h | 18 ++++++++
    5 files changed, 125 insertions(+)

    diff --git a/drivers/cdx/cdx.c b/drivers/cdx/cdx.c
    index d2cad4c670a0..9efb7584f952 100644
    --- a/drivers/cdx/cdx.c
    +++ b/drivers/cdx/cdx.c
    @@ -182,6 +182,38 @@ cdx_match_id(const struct cdx_device_id *ids, struct cdx_device *dev)
    return NULL;
    }

    +int cdx_set_master(struct cdx_device *cdx_dev)
    +{
    + struct cdx_controller *cdx = cdx_dev->cdx;
    + struct cdx_device_config dev_config;
    + int ret = -EOPNOTSUPP;
    +
    + dev_config.type = CDX_DEV_BUS_MASTER_CONF;
    + dev_config.bus_master_enable = true;
    + if (cdx->ops->dev_configure)
    + ret = cdx->ops->dev_configure(cdx, cdx_dev->bus_num,
    + cdx_dev->dev_num, &dev_config);
    +
    + return ret;
    +}
    +EXPORT_SYMBOL_GPL(cdx_set_master);
    +
    +int cdx_clear_master(struct cdx_device *cdx_dev)
    +{
    + struct cdx_controller *cdx = cdx_dev->cdx;
    + struct cdx_device_config dev_config;
    + int ret = -EOPNOTSUPP;
    +
    + dev_config.type = CDX_DEV_BUS_MASTER_CONF;
    + dev_config.bus_master_enable = false;
    + if (cdx->ops->dev_configure)
    + ret = cdx->ops->dev_configure(cdx, cdx_dev->bus_num,
    + cdx_dev->dev_num, &dev_config);
    +
    + return ret;
    +}
    +EXPORT_SYMBOL_GPL(cdx_clear_master);
    +
    /**
    * cdx_bus_match - device to driver matching callback
    * @dev: the cdx device to match against
    diff --git a/drivers/cdx/controller/cdx_controller.c b/drivers/cdx/controller/cdx_controller.c
    index dc52f95f8978..39aa569d8e07 100644
    --- a/drivers/cdx/controller/cdx_controller.c
    +++ b/drivers/cdx/controller/cdx_controller.c
    @@ -55,6 +55,10 @@ static int cdx_configure_device(struct cdx_controller *cdx,
    case CDX_DEV_RESET_CONF:
    ret = cdx_mcdi_reset_device(cdx->priv, bus_num, dev_num);
    break;
    + case CDX_DEV_BUS_MASTER_CONF:
    + ret = cdx_mcdi_bus_master_enable(cdx->priv, bus_num, dev_num,
    + dev_config->bus_master_enable);
    + break;
    default:
    ret = -EINVAL;
    }
    diff --git a/drivers/cdx/controller/mcdi_functions.c b/drivers/cdx/controller/mcdi_functions.c
    index 0158f26533dd..6acd8fea4586 100644
    --- a/drivers/cdx/controller/mcdi_functions.c
    +++ b/drivers/cdx/controller/mcdi_functions.c
    @@ -137,3 +137,61 @@ int cdx_mcdi_reset_device(struct cdx_mcdi *cdx, u8 bus_num, u8 dev_num)

    return ret;
    }
    +
    +static int cdx_mcdi_ctrl_flag_get(struct cdx_mcdi *cdx, u8 bus_num,
    + u8 dev_num, u32 *flags)
    +{
    + MCDI_DECLARE_BUF(inbuf, MC_CMD_CDX_DEVICE_CONTROL_GET_IN_LEN);
    + MCDI_DECLARE_BUF(outbuf, MC_CMD_CDX_DEVICE_CONTROL_GET_OUT_LEN);
    + size_t outlen;
    + int ret;
    +
    + MCDI_SET_DWORD(inbuf, CDX_DEVICE_CONTROL_GET_IN_BUS, bus_num);
    + MCDI_SET_DWORD(inbuf, CDX_DEVICE_CONTROL_GET_IN_DEVICE, dev_num);
    + ret = cdx_mcdi_rpc(cdx, MC_CMD_CDX_DEVICE_CONTROL_GET, inbuf,
    + sizeof(inbuf), outbuf, sizeof(outbuf), &outlen);
    + if (ret)
    + return ret;
    +
    + if (outlen != MC_CMD_CDX_DEVICE_CONTROL_GET_OUT_LEN)
    + return -EIO;
    +
    + *flags = MCDI_DWORD(outbuf, CDX_DEVICE_CONTROL_GET_OUT_FLAGS);
    +
    + return 0;
    +}
    +
    +static int cdx_mcdi_ctrl_flag_set(struct cdx_mcdi *cdx, u8 bus_num,
    + u8 dev_num, bool enable, int bit_pos)
    +{
    + MCDI_DECLARE_BUF(inbuf, MC_CMD_CDX_DEVICE_CONTROL_SET_IN_LEN);
    + u32 flags;
    + int ret;
    +
    + /*
    + * Get flags and then set/reset bit at bit_pos according to
    + * the input params.
    + */
    + ret = cdx_mcdi_ctrl_flag_get(cdx, bus_num, dev_num, &flags);
    + if (ret)
    + return ret;
    +
    + flags = flags & (u32)(~(BIT(bit_pos)));
    + if (enable)
    + flags |= (1 << bit_pos);
    +
    + MCDI_SET_DWORD(inbuf, CDX_DEVICE_CONTROL_SET_IN_BUS, bus_num);
    + MCDI_SET_DWORD(inbuf, CDX_DEVICE_CONTROL_SET_IN_DEVICE, dev_num);
    + MCDI_SET_DWORD(inbuf, CDX_DEVICE_CONTROL_SET_IN_FLAGS, flags);
    + ret = cdx_mcdi_rpc(cdx, MC_CMD_CDX_DEVICE_CONTROL_SET, inbuf,
    + sizeof(inbuf), NULL, 0, NULL);
    +
    + return ret;
    +}
    +
    +int cdx_mcdi_bus_master_enable(struct cdx_mcdi *cdx, u8 bus_num,
    + u8 dev_num, bool enable)
    +{
    + return cdx_mcdi_ctrl_flag_set(cdx, bus_num, dev_num, enable,
    + MC_CMD_CDX_DEVICE_CONTROL_SET_IN_BUS_MASTER_ENABLE_LBN);
    +}
    diff --git a/drivers/cdx/controller/mcdi_functions.h b/drivers/cdx/controller/mcdi_functions.h
    index 7440ace5539a..a448d6581eb4 100644
    --- a/drivers/cdx/controller/mcdi_functions.h
    +++ b/drivers/cdx/controller/mcdi_functions.h
    @@ -58,4 +58,17 @@ int cdx_mcdi_get_dev_config(struct cdx_mcdi *cdx,
    int cdx_mcdi_reset_device(struct cdx_mcdi *cdx,
    u8 bus_num, u8 dev_num);

    +/**
    + * cdx_mcdi_bus_master_enable - Set/Reset bus mastering for cdx device
    + * represented by bus_num:dev_num
    + * @cdx: pointer to MCDI interface.
    + * @bus_num: Bus number.
    + * @dev_num: Device number.
    + * @enable: Enable bus mastering if set, disable otherwise.
    + *
    + * Return: 0 on success, <0 on failure
    + */
    +int cdx_mcdi_bus_master_enable(struct cdx_mcdi *cdx, u8 bus_num,
    + u8 dev_num, bool enable);
    +
    #endif /* CDX_MCDI_FUNCTIONS_H */
    diff --git a/include/linux/cdx/cdx_bus.h b/include/linux/cdx/cdx_bus.h
    index bead71b7bc73..8320ec3b9e37 100644
    --- a/include/linux/cdx/cdx_bus.h
    +++ b/include/linux/cdx/cdx_bus.h
    @@ -21,11 +21,13 @@
    struct cdx_controller;

    enum {
    + CDX_DEV_BUS_MASTER_CONF,
    CDX_DEV_RESET_CONF,
    };

    struct cdx_device_config {
    u8 type;
    + bool bus_master_enable;
    };

    typedef int (*cdx_scan_cb)(struct cdx_controller *cdx);
    @@ -170,4 +172,20 @@ extern struct bus_type cdx_bus_type;
    */
    int cdx_dev_reset(struct device *dev);

    +/**
    + * cdx_set_master - enables bus-mastering for CDX device
    + * @cdx_dev: the CDX device to enable
    + *
    + * Return: 0 for success, -errno on failure
    + */
    +int cdx_set_master(struct cdx_device *cdx_dev);
    +
    +/**
    + * cdx_clear_master - disables bus-mastering for CDX device
    + * @cdx_dev: the CDX device to disable
    + *
    + * Return: 0 for success, -errno on failure
    + */
    +int cdx_clear_master(struct cdx_device *cdx_dev);
    +
    #endif /* _CDX_BUS_H_ */
    --
    2.17.1
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