Re: [PATCH] cdx: add support for bus mastering

From: Greg KH
Date: Tue Jul 18 2023 - 09:47:19 EST

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In reply to: Nipun Gupta: "[PATCH] cdx: add support for bus mastering"
Next in thread: Gupta, Nipun: "Re: [PATCH] cdx: add support for bus mastering"
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On Tue, Jul 18, 2023 at 03:36:51PM +0530, Nipun Gupta wrote:
> 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.

You do have a full 72 columns, why not use that?

> Signed-off-by: Nipun Gupta <nipun.gupta@xxxxxxx>
> Reviewed-by: Pieter Jansen van Vuuren <pieter.jansen-van-vuuren@xxxxxxx>
> ---
> drivers/cdx/cdx.c | 32 ++++++++++++++
> drivers/cdx/controller/cdx_controller.c | 4 ++
> drivers/cdx/controller/mcdi_functions.c | 57 +++++++++++++++++++++++++
> drivers/cdx/controller/mcdi_functions.h | 13 ++++++
> include/linux/cdx/cdx_bus.h | 16 +++++++
> 5 files changed, 122 insertions(+)
>
> diff --git a/drivers/cdx/cdx.c b/drivers/cdx/cdx.c
> index d2cad4c670a0..efb24672b7d9 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;
> +
> + dev_config.type = CDX_DEV_BUS_MASTER_CONF;
> + dev_config.bme = true;

What is "bme"?

And are you sure that the config can be on the stack?

> + ret = cdx->ops->dev_configure(cdx, cdx_dev->bus_num,
> + cdx_dev->dev_num, &dev_config);

Will dev_configure always be there?

> + if (ret)
> + dev_err(&cdx_dev->dev, "device master enable failed\n");

Why error out here, shouldn't the call have printed something if it
wanted to?

> +
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(cdx_set_master);
> +
> +void cdx_clear_master(struct cdx_device *cdx_dev)
> +{
> + struct cdx_controller *cdx = cdx_dev->cdx;
> + struct cdx_device_config dev_config;
> + int ret;
> +
> + dev_config.type = CDX_DEV_BUS_MASTER_CONF;
> + dev_config.bme = false;
> + ret = cdx->ops->dev_configure(cdx, cdx_dev->bus_num,
> + cdx_dev->dev_num, &dev_config);
> + if (ret)
> + dev_err(&cdx_dev->dev, "device master disable failed\n");

Same question as above.

> +}
> +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..ba670f0427d3 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->bme);
> + break;
> default:
> ret = -EINVAL;
> }
> diff --git a/drivers/cdx/controller/mcdi_functions.c b/drivers/cdx/controller/mcdi_functions.c
> index 0158f26533dd..c4c00f376006 100644
> --- a/drivers/cdx/controller/mcdi_functions.c
> +++ b/drivers/cdx/controller/mcdi_functions.c
> @@ -137,3 +137,60 @@ 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);

How big are these buffers?

> + 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 lbn)
> +{
> + MCDI_DECLARE_BUF(inbuf, MC_CMD_CDX_DEVICE_CONTROL_SET_IN_LEN);
> + int ret, en;
> + u32 flags;
> +
> + /*
> + * Get flags and then set/reset BUS_MASTER_BIT according to
> + * the input params.
> + */
> + ret = cdx_mcdi_ctrl_flag_get(cdx, bus_num, dev_num, &flags);
> + if (ret)
> + return ret;
> +
> + en = enable ? 1 : 0;

if/then/else?

> + flags = (flags & (u32)(~(BIT(lbn)))) | (en << lbn);
> +
> + 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..acb4e40bd20e 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 bme;

What does "bme" mean?

thanks,

greg k-h

Next message: Joel Fernandes: "Re: [PATCH rcu 5/6] rcu: Make the rcu_nocb_poll boot parameter usable via boot config"
Previous message: Konrad Dybcio: "Re: [PATCH 0/8] clk: qcom: fix runtime PM bugs"
In reply to: Nipun Gupta: "[PATCH] cdx: add support for bus mastering"
Next in thread: Gupta, Nipun: "Re: [PATCH] cdx: add support for bus mastering"
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