Re: [PATCH v3 4/5] remoteproc: imx_rproc: Add support for System Manager API

[Frank Li <Frank.li@nxp.com>]

On Sat, Nov 22, 2025 at 08:58:19AM +0800, Peng Fan (OSS) wrote:
> From: Peng Fan <peng.fan@nxp.com>
>
> i.MX95 features a Cortex-M33 core, six Cortex-A55 cores, and
> one Cortex-M7 core. The System Control Management Interface(SCMI)
> firmware runs on the M33 core. The i.MX95 SCMI firmware named System
> Manager(SM) includes vendor extension protocols, Logical Machine
> Management(LMM) protocol and CPU protocol and etc.
>
> Depending on SM configuration, M7 can be used as follows:
>  (1) M7 in a separate Logical Machine (LM) from A55 cores, that Linux
>      can't control
>  (2) M7 in a separate LM from A55 cores that Linux can control using LMM
>      protocol.
>  (3) M7 runs in same Logical Machine as A55 cores, so Linux can control it
>      using CPU protocol
>
> So extend the driver to using LMM and CPU protocol to manage the M7 core.
>  - Compare linux LM ID(got using scmi_imx_lmm_info) and M7 LM ID(the ID
>    is fixed as 1 in SM firmware if M7 is in a separate LM),
>    if Linux LM ID equals M7 LM ID(linux and M7 in same LM), use CPU
>    protocol to start/stop. Otherwise, use LMM protocol to start/stop.
>    Whether using CPU or LMM protocol to start/stop, the M7 status
>    detection could use CPU protocol to detect started or not. So
>    in imx_rproc_detect_mode, use scmi_imx_cpu_started to check the
>    status of M7.
>  - For above case (1) and (2), Use SCMI_IMX_LMM_POWER_ON to detect whether
>    the M7 LM is under control of A55 LM.
>  - For above case , after using SCMI_IMX_LMM_POWER_ON to check
>    permission, SCMI_IMX_LMM_SHUTDOWN API should be called to shutdown
>    the M7 LM to save power only when M7 LM is going to be started by
>    remoteproc framework. Otherwise bypass SCMI_IMX_LMM_SHUTDOWN API if
>    M7 LM is started before booting Linux.
>
> Current setup relies on pre-Linux software(U-Boot) to do M7 TCM ECC
> initialization. In future, we could add the support in Linux to decouple
> U-Boot and Linux.
>
> Signed-off-by: Peng Fan <peng.fan@nxp.com>
> ---
>  drivers/remoteproc/Kconfig     |   2 +
>  drivers/remoteproc/imx_rproc.c | 193 +++++++++++++++++++++++++++++++++++++++++
>  drivers/remoteproc/imx_rproc.h |   3 +
>  3 files changed, 198 insertions(+)
>
...
> +
> +static int imx_rproc_sm_lmm_check(struct rproc *rproc, bool started)
> +{
> +	struct imx_rproc *priv = rproc->priv;
> +	const struct imx_rproc_dcfg *dcfg = priv->dcfg;
> +	struct device *dev = priv->dev;
> +	int ret;
> +
> +	/*
> +	 * Use power on to do permission check. If rproc is in different LM,
> +	 * and linux has permission to handle the LM, set IMX_RPROC_FLAGS_SM_LMM_AVAIL.
> +	 */
> +	ret = scmi_imx_lmm_operation(dcfg->lmid, SCMI_IMX_LMM_POWER_ON, 0);
> +	if (ret != 0) {

if (ret)

> +		if (ret == -EACCES) {
> +			/*
> +			 * rproc LM is booted before Linux and not under Linux Control, so only
> +			 * do IPC between RPROC and Linux, not return failure
> +			 */
> +			dev_info(dev, "lmm(%d) not under Linux Control\n", dcfg->lmid);
> +			return 0;
> +		}
> +
> +		dev_err(dev, "power on lmm(%d) failed: %d\n", dcfg->lmid, ret);
> +		return ret;
> +	}
> +
> +	priv->flags |= IMX_RPROC_FLAGS_SM_LMM_AVAIL;
> +
> +	/* rproc was started before boot Linux and under control of Linux, directly return */
> +	if (started)
> +		return 0;

should it be before scmi_imx_lmm_operation()? If started, supposed need
check scmi_imx_lmm_operation()?

Frank
> +
> +	/* else shutdown the LM to save power */
> +	ret = scmi_imx_lmm_operation(dcfg->lmid, SCMI_IMX_LMM_SHUTDOWN, 0);
> +	if (ret) {
> +		priv->flags &= ~IMX_RPROC_FLAGS_SM_LMM_AVAIL;
> +		dev_err(dev, "shutdown lmm(%d) failed: %d\n", dcfg->lmid, ret);
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
...
>  };
>
>  #endif /* _IMX_RPROC_H */
>
> --
> 2.37.1
>