remoteproc: imx_rproc: Add support for System Manager LMM API

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 is not same as M7 LM ID(linux and M7 in same LM), use
LMM protocol to start/stop. CPU protocol support will be added in the
following patch. 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.

Reviewed-by: Daniel Baluta <[e-mail]>
Reviewed-by: Frank Li <[e-mail]>
Signed-off-by: Peng Fan <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Mathieu Poirier <[e-mail]>

drivers/remoteproc/Kconfig

···
 	tristate "i.MX remoteproc support"
 	depends on ARCH_MXC
 	depends on HAVE_ARM_SMCCC
+	depends on IMX_SCMI_CPU_DRV || !IMX_SCMI_CPU_DRV
+	depends on IMX_SCMI_LMM_DRV || !IMX_SCMI_LMM_DRV
 	select MAILBOX
 	help
 	  Say y here to support iMX's remote processors via the remote

drivers/remoteproc/imx_rproc.c

···
 #include <linux/clk.h>
 #include <linux/err.h>
 #include <linux/firmware/imx/sci.h>
+#include <linux/firmware/imx/sm.h>
 #include <linux/interrupt.h>
 #include <linux/kernel.h>
 #include <linux/mailbox_client.h>
···
 #include <linux/reboot.h>
 #include <linux/regmap.h>
 #include <linux/remoteproc.h>
+#include <linux/scmi_imx_protocol.h>
 #include <linux/workqueue.h>
 
 #include "imx_rproc.h"
···
 #define ATT_CORE_MASK   0xffff
 #define ATT_CORE(I)     BIT((I))
 
+/* Linux has permission to handle the Logical Machine of remote cores */
+#define IMX_RPROC_FLAGS_SM_LMM_CTRL	BIT(0)
+
 static int imx_rproc_xtr_mbox_init(struct rproc *rproc, bool tx_block);
 static void imx_rproc_free_mbox(void *data);
+
+/* Forward declarations for platform operations */
+static const struct imx_rproc_plat_ops imx_rproc_ops_sm_lmm;
 
 struct imx_rproc {
 	struct device			*dev;
···
 	u32				core_index;
 	struct dev_pm_domain_list	*pd_list;
 	const struct imx_rproc_plat_ops	*ops;
+	/*
+	 * For i.MX System Manager based systems
+	 * BIT 0: IMX_RPROC_FLAGS_SM_LMM_CTRL(RPROC LM is under Linux control )
+	 */
+	u32				flags;
 };
 
 static const struct imx_rproc_att imx_rproc_att_imx93[] = {
···
 	return imx_sc_pm_cpu_start(priv->ipc_handle, priv->rsrc_id, true, priv->entry);
 }
 
+static int imx_rproc_sm_lmm_start(struct rproc *rproc)
+{
+	struct imx_rproc *priv = rproc->priv;
+	const struct imx_rproc_dcfg *dcfg = priv->dcfg;
+	struct device *dev = priv->dev;
+	int ret;
+
+	/*
+	 * If the remoteproc core can't start the M7, it will already be
+	 * handled in imx_rproc_sm_lmm_prepare().
+	 */
+	ret = scmi_imx_lmm_reset_vector_set(dcfg->lmid, dcfg->cpuid, 0, 0);
+	if (ret) {
+		dev_err(dev, "Failed to set reset vector lmid(%u), cpuid(%u): %d\n",
+			dcfg->lmid, dcfg->cpuid, ret);
+		return ret;
+	}
+
+	ret = scmi_imx_lmm_operation(dcfg->lmid, SCMI_IMX_LMM_BOOT, 0);
+	if (ret) {
+		dev_err(dev, "Failed to boot lmm(%d): %d\n", dcfg->lmid, ret);
+		return ret;
+	}
+
+	return 0;
+}
+
 static int imx_rproc_start(struct rproc *rproc)
 {
 	struct imx_rproc *priv = rproc->priv;
···
 	struct imx_rproc *priv = rproc->priv;
 
 	return imx_sc_pm_cpu_start(priv->ipc_handle, priv->rsrc_id, false, priv->entry);
+}
+
+static int imx_rproc_sm_lmm_stop(struct rproc *rproc)
+{
+	struct imx_rproc *priv = rproc->priv;
+	const struct imx_rproc_dcfg *dcfg = priv->dcfg;
+
+	if (!(priv->flags & IMX_RPROC_FLAGS_SM_LMM_CTRL))
+		return -EACCES;
+
+	return scmi_imx_lmm_operation(dcfg->lmid, SCMI_IMX_LMM_SHUTDOWN, 0);
 }
 
 static int imx_rproc_stop(struct rproc *rproc)
···
 {
 	dev_dbg(rproc->dev.parent, "unmap memory: %pa\n", &mem->dma);
 	iounmap(mem->va);
+
+	return 0;
+}
+
+static int imx_rproc_sm_lmm_prepare(struct rproc *rproc)
+{
+	struct imx_rproc *priv = rproc->priv;
+	const struct imx_rproc_dcfg *dcfg = priv->dcfg;
+	int ret;
+
+	/*
+	 * IMX_RPROC_FLAGS_SM_LMM_CTRL not set indicates Linux is not able
+	 * to start/stop M7, then if rproc is not in detached state,
+	 * prepare should fail. If in detached state, this is in rproc_attach()
+	 * path.
+	 */
+	if (rproc->state == RPROC_DETACHED)
+		return 0;
+
+	if (!(priv->flags & IMX_RPROC_FLAGS_SM_LMM_CTRL))
+		return -EACCES;
+
+	/* Power on the Logical Machine to make sure TCM is available. */
+	ret = scmi_imx_lmm_operation(dcfg->lmid, SCMI_IMX_LMM_POWER_ON, 0);
+	if (ret) {
+		dev_err(priv->dev, "Failed to power on lmm(%d): %d\n", dcfg->lmid, ret);
+		return ret;
+	}
+
+	dev_info(priv->dev, "lmm(%d) powered on by Linux\n", dcfg->lmid);
 
 	return 0;
 }
···
 	return 0;
 }
 
+/* Check whether remoteproc core is responsible for M7 lifecycle */
+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;
+
+	ret = scmi_imx_lmm_operation(dcfg->lmid, SCMI_IMX_LMM_POWER_ON, 0);
+	if (ret) {
+		if (ret == -EACCES) {
+			/*
+			 * M7 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;
+	}
+
+	/* Shutdown remote processor if not started */
+	if (!started) {
+		ret = scmi_imx_lmm_operation(dcfg->lmid, SCMI_IMX_LMM_SHUTDOWN, 0);
+		if (ret) {
+			dev_err(dev, "shutdown lmm(%d) failed: %d\n", dcfg->lmid, ret);
+			return ret;
+		}
+	}
+
+	priv->flags |= IMX_RPROC_FLAGS_SM_LMM_CTRL;
+
+	return 0;
+}
+
+static int imx_rproc_sm_detect_mode(struct rproc *rproc)
+{
+	struct imx_rproc *priv = rproc->priv;
+	const struct imx_rproc_dcfg *dcfg = priv->dcfg;
+	struct device *dev = priv->dev;
+	struct scmi_imx_lmm_info info;
+	bool started = false;
+	int ret;
+
+	ret = scmi_imx_cpu_started(dcfg->cpuid, &started);
+	if (ret) {
+		dev_err(dev, "Failed to detect cpu(%d) status: %d\n", dcfg->cpuid, ret);
+		return ret;
+	}
+
+	if (started)
+		priv->rproc->state = RPROC_DETACHED;
+
+	/* Get current Linux Logical Machine ID */
+	ret = scmi_imx_lmm_info(LMM_ID_DISCOVER, &info);
+	if (ret) {
+		dev_err(dev, "Failed to get current LMM ID err: %d\n", ret);
+		return ret;
+	}
+
+	/*
+	 * Check whether M7 is in the same LM as host core(running Linux)
+	 * If yes, use CPU protocol API to manage M7.
+	 * If no, use Logical Machine API to manage M7.
+	 */
+	if (dcfg->lmid == info.lmid) {
+		dev_err(dev, "CPU Protocol OPS is not supported\n");
+		return -EOPNOTSUPP;
+	}
+
+	priv->ops = &imx_rproc_ops_sm_lmm;
+	dev_info(dev, "Using LMM Protocol OPS\n");
+
+	return imx_rproc_sm_lmm_check(rproc, started);
+}
+
 static int imx_rproc_detect_mode(struct imx_rproc *priv)
 {
 	/*
···
 	.stop		= imx_rproc_scu_api_stop,
 	.detach		= imx_rproc_scu_api_detach,
 	.detect_mode	= imx_rproc_scu_api_detect_mode,
+};
+
+static const struct imx_rproc_plat_ops imx_rproc_ops_sm_lmm = {
+	.detect_mode	= imx_rproc_sm_detect_mode,
+	.prepare	= imx_rproc_sm_lmm_prepare,
+	.start		= imx_rproc_sm_lmm_start,
+	.stop		= imx_rproc_sm_lmm_stop,
 };
 
 static const struct imx_rproc_dcfg imx_rproc_cfg_imx8mn_mmio = {

drivers/remoteproc/imx_rproc.h

···
 	size_t				att_size;
 	u32				flags;
 	const struct imx_rproc_plat_ops	*ops;
+	/* For System Manager(SM) based SoCs */
+	u32				cpuid; /* ID of the remote core */
+	u32				lmid;  /* ID of the Logcial Machine */
 };
 
 #endif /* _IMX_RPROC_H */