Re: [PATCH 4/6] remoteproc: k3-r5: Add support for IPC-only mode for all R5Fs

Mathieu Poirier
2021-06-02T15:55:17Z

I've been thinking about this patch again...

On Fri, May 21, 2021 at 07:03:07PM -0500, Suman Anna wrote:
> Add support to the K3 R5F remoteproc driver to configure all the R5F
> cores to be either in IPC-only mode or the traditional remoteproc mode.
> The IPC-only mode expects that the remote processors are already booted
> by the bootloader, and only performs the minimum steps required to
> initialize and deinitialize the virtio IPC transports. The remoteproc
> mode allows the kernel remoteproc driver to do the regular load and
> boot and other device management operations for a R5F core.
>
> The IPC-only mode for a R5F core is detected and configured at driver
> probe time by querying the System Firmware for the R5F power and reset
> state and/or status and making sure that the R5F core is indeed started
> by the bootloaders, otherwise the device is configured for remoteproc
> mode.
>
> Support for IPC-only mode is achieved through .attach(), .detach() and
> .get_loaded_rsc_table() callback ops and various other flags in both
> remoteproc core and the K3 R5F remoteproc driver. The resource table
> follows a design-by-contract approach and is expected to be at the base
> of the DDR firmware region reserved for each remoteproc, it is mostly
> expected to contain only the virtio device and trace resource entries.
>
> NOTE:
> The driver cannot configure a R5F core for remoteproc mode by any
> means without rebooting the kernel if that R5F core has been started
> by a bootloader.
>
> Signed-off-by: Suman Anna <s-anna@ti.com>
> ---
> drivers/remoteproc/ti_k3_r5_remoteproc.c | 215 +++++++++++++++++++++++
> 1 file changed, 215 insertions(+)
>
> diff --git a/drivers/remoteproc/ti_k3_r5_remoteproc.c b/drivers/remoteproc/ti_k3_r5_remoteproc.c
> index e7e1ca71763e..66f0654f0860 100644
> --- a/drivers/remoteproc/ti_k3_r5_remoteproc.c
> +++ b/drivers/remoteproc/ti_k3_r5_remoteproc.c
> @@ -151,6 +151,7 @@ struct k3_r5_core {
> * @core: cached pointer to r5 core structure being used
> * @rmem: reserved memory regions data
> * @num_rmems: number of reserved memory regions
> + * @ipc_only: flag to indicate IPC-only mode
> */
> struct k3_r5_rproc {
> struct device *dev;
> @@ -161,6 +162,7 @@ struct k3_r5_rproc {
> struct k3_r5_core *core;
> struct k3_r5_mem *rmem;
> int num_rmems;
> + bool ipc_only;
> };
>
> /**
> @@ -440,6 +442,10 @@ static int k3_r5_rproc_prepare(struct rproc *rproc)
> bool mem_init_dis;
> int ret;
>
> + /* IPC-only mode does not require the cores to be released from reset */
> + if (kproc->ipc_only)
> + return 0;
> +
> ret = ti_sci_proc_get_status(core->tsp, &boot_vec, &cfg, &ctrl, &stat);
> if (ret < 0)
> return ret;
> @@ -503,6 +509,10 @@ static int k3_r5_rproc_unprepare(struct rproc *rproc)
> struct device *dev = kproc->dev;
> int ret;
>
> + /* do not put back the cores into reset in IPC-only mode */
> + if (kproc->ipc_only)
> + return 0;
> +
> /* Re-use LockStep-mode reset logic for Single-CPU mode */
> ret = (cluster->mode == CLUSTER_MODE_LOCKSTEP ||
> cluster->mode == CLUSTER_MODE_SINGLECPU) ?
> @@ -538,6 +548,12 @@ static int k3_r5_rproc_start(struct rproc *rproc)
> u32 boot_addr;
> int ret;
>
> + if (kproc->ipc_only) {
> + dev_err(dev, "%s cannot be invoked in IPC-only mode\n",
> + __func__);
> + return -EINVAL;
> + }
> +
> ret = k3_r5_rproc_request_mbox(rproc);
> if (ret)
> return ret;
> @@ -604,9 +620,16 @@ static int k3_r5_rproc_stop(struct rproc *rproc)
> {
> struct k3_r5_rproc *kproc = rproc->priv;
> struct k3_r5_cluster *cluster = kproc->cluster;
> + struct device *dev = kproc->dev;
> struct k3_r5_core *core = kproc->core;
> int ret;
>
> + if (kproc->ipc_only) {
> + dev_err(dev, "%s cannot be invoked in IPC-only mode\n",
> + __func__);
> + return -EINVAL;
> + }
> +

It would be much cleaner to simply not provide any of the above functions to
rproc_ops when in IPC only mode.

> /* halt all applicable cores */
> if (cluster->mode == CLUSTER_MODE_LOCKSTEP) {
> list_for_each_entry(core, &cluster->cores, elem) {
> @@ -635,6 +658,85 @@ static int k3_r5_rproc_stop(struct rproc *rproc)
> return ret;
> }
>
> +/*
> + * Attach to a running R5F remote processor (IPC-only mode)
> + *
> + * The R5F attach callback only needs to request the mailbox, the remote
> + * processor is already booted, so there is no need to issue any TI-SCI
> + * commands to boot the R5F cores in IPC-only mode.
> + */
> +static int k3_r5_rproc_attach(struct rproc *rproc)
> +{
> + struct k3_r5_rproc *kproc = rproc->priv;
> + struct device *dev = kproc->dev;
> + int ret;
> +
> + if (!kproc->ipc_only || rproc->state != RPROC_DETACHED) {
> + dev_err(dev, "R5F is expected to be in IPC-only mode and RPROC_DETACHED state\n");
> + return -EINVAL;
> + }

Not sure this condition is needed since this can only be called by the core if
state == RPROC_DETACHED, same for k3_r5_rproc_detach() below. And because we are
in k3_r5_rproc_attach/detach() we can only be in IPC only mode, which means that
k3_r5_proc::ipc_only mode shouldn't be needed.

> +
> + ret = k3_r5_rproc_request_mbox(rproc);
> + if (ret)
> + return ret;
> +
> + dev_err(dev, "R5F core initialized in IPC-only mode\n");
> + return 0;
> +}
> +
> +/*
> + * Detach from a running R5F remote processor (IPC-only mode)
> + *
> + * The R5F detach callback performs the opposite operation to attach callback
> + * and only needs to release the mailbox, the R5F cores are not stopped and
> + * will be left in booted state in IPC-only mode.
> + */
> +static int k3_r5_rproc_detach(struct rproc *rproc)
> +{
> + struct k3_r5_rproc *kproc = rproc->priv;
> + struct device *dev = kproc->dev;
> +
> + if (!kproc->ipc_only || rproc->state != RPROC_ATTACHED) {
> + dev_err(dev, "R5F is expected to be in IPC-only mode and RPROC_ATTACHED state\n");
> + return -EINVAL;
> + }
> +
> + mbox_free_channel(kproc->mbox);
> + dev_err(dev, "R5F core deinitialized in IPC-only mode\n");
> + return 0;
> +}
> +
> +/*
> + * This function implements the .get_loaded_rsc_table() callback and is used
> + * to provide the resource table for the booted R5F in IPC-only mode. The K3 R5F
> + * firmwares follow a design-by-contract approach and are expected to have the
> + * resource table at the base of the DDR region reserved for firmware usage.
> + * This provides flexibility for the remote processor to be booted by different
> + * bootloaders that may or may not have the ability to publish the resource table
> + * address and size through a DT property.
> + */
> +static struct resource_table *k3_r5_get_loaded_rsc_table(struct rproc *rproc,
> + size_t *rsc_table_sz)
> +{
> + struct k3_r5_rproc *kproc = rproc->priv;
> + struct device *dev = kproc->dev;
> +
> + if (!kproc->rmem[0].cpu_addr) {
> + dev_err(dev, "memory-region #1 does not exist, loaded rsc table can't be found");
> + return ERR_PTR(-ENOMEM);
> + }
> +
> + /*
> + * NOTE: The resource table size is currently hard-coded to a maximum
> + * of 256 bytes. The most common resource table usage for K3 firmwares
> + * is to only have the vdev resource entry and an optional trace entry.
> + * The exact size could be computed based on resource table address, but
> + * the hard-coded value suffices to support the IPC-only mode.
> + */
> + *rsc_table_sz = 256;
> + return (struct resource_table *)kproc->rmem[0].cpu_addr;
> +}
> +
> /*
> * Internal Memory translation helper
> *
> @@ -709,8 +811,11 @@ static const struct rproc_ops k3_r5_rproc_ops = {
> .unprepare = k3_r5_rproc_unprepare,
> .start = k3_r5_rproc_start,
> .stop = k3_r5_rproc_stop,
> + .attach = k3_r5_rproc_attach,
> + .detach = k3_r5_rproc_detach,
> .kick = k3_r5_rproc_kick,
> .da_to_va = k3_r5_rproc_da_to_va,
> + .get_loaded_rsc_table = k3_r5_get_loaded_rsc_table,
> };
>
> /*
> @@ -1014,6 +1119,109 @@ static void k3_r5_adjust_tcm_sizes(struct k3_r5_rproc *kproc)
> }
> }
>
> +/*
> + * This function checks and configures a R5F core for IPC-only or remoteproc
> + * mode. The driver is configured to be in IPC-only mode for a R5F core when
> + * the core has been loaded and started by a bootloader. The IPC-only mode is
> + * detected by querying the System Firmware for reset, power on and halt status
> + * and ensuring that the core is running. Any incomplete steps at bootloader
> + * are validated and errored out.
> + *
> + * In IPC-only mode, the driver state flags for ATCM, BTCM and LOCZRAMA settings
> + * and cluster mode parsed originally from kernel DT are updated to reflect the
> + * actual values configured by bootloader. The driver internal device memory
> + * addresses for TCMs are also updated.
> + */
> +static int k3_r5_rproc_configure_mode(struct k3_r5_rproc *kproc)
> +{
> + struct k3_r5_cluster *cluster = kproc->cluster;
> + struct k3_r5_core *core = kproc->core;
> + struct device *cdev = core->dev;
> + bool r_state = false, c_state = false;
> + u32 ctrl = 0, cfg = 0, stat = 0, halted = 0;
> + u64 boot_vec = 0;
> + u32 atcm_enable, btcm_enable, loczrama;
> + struct k3_r5_core *core0;
> + enum cluster_mode mode;
> + int ret;
> +
> + core0 = list_first_entry(&cluster->cores, struct k3_r5_core, elem);
> +
> + ret = core->ti_sci->ops.dev_ops.is_on(core->ti_sci, core->ti_sci_id,
> + &r_state, &c_state);
> + if (ret) {
> + dev_err(cdev, "failed to get initial state, mode cannot be determined, ret = %d\n",
> + ret);
> + return ret;
> + }
> + if (r_state != c_state) {
> + dev_warn(cdev, "R5F core may have been powered on by a different host, programmed state (%d) != actual state (%d)\n",
> + r_state, c_state);
> + }
> +
> + ret = reset_control_status(core->reset);
> + if (ret < 0) {
> + dev_err(cdev, "failed to get initial local reset status, ret = %d\n",
> + ret);
> + return ret;
> + }
> +
> + ret = ti_sci_proc_get_status(core->tsp, &boot_vec, &cfg, &ctrl,
> + &stat);
> + if (ret < 0) {
> + dev_err(cdev, "failed to get initial processor status, ret = %d\n",
> + ret);
> + return ret;
> + }
> + atcm_enable = cfg & PROC_BOOT_CFG_FLAG_R5_ATCM_EN ? 1 : 0;
> + btcm_enable = cfg & PROC_BOOT_CFG_FLAG_R5_BTCM_EN ? 1 : 0;
> + loczrama = cfg & PROC_BOOT_CFG_FLAG_R5_TCM_RSTBASE ? 1 : 0;
> + if (cluster->soc_data->single_cpu_mode) {
> + mode = cfg & PROC_BOOT_CFG_FLAG_R5_SINGLE_CORE ?
> + CLUSTER_MODE_SINGLECPU : CLUSTER_MODE_SPLIT;
> + } else {
> + mode = cfg & PROC_BOOT_CFG_FLAG_R5_LOCKSTEP ?
> + CLUSTER_MODE_LOCKSTEP : CLUSTER_MODE_SPLIT;
> + }
> + halted = ctrl & PROC_BOOT_CTRL_FLAG_R5_CORE_HALT;
> +
> + /*
> + * IPC-only mode detection requires both local and module resets to
> + * be deasserted and R5F core to be unhalted. Local reset status is
> + * irrelevant if module reset is asserted (POR value has local reset
> + * deasserted), and is deemed as remoteproc mode
> + */
> + if (c_state && !ret && !halted) {
> + dev_err(cdev, "configured R5F for IPC-only mode\n");
> + kproc->rproc->state = RPROC_DETACHED;
> + kproc->rproc->detach_on_shutdown = true;
> + kproc->ipc_only = true;
> + ret = 1;
> + } else if (!c_state) {
> + dev_err(cdev, "configured R5F for remoteproc mode\n");
> + ret = 0;
> + } else {
> + dev_err(cdev, "mismatched mode: local_reset = %s, module_reset = %s, core_state = %s\n",
> + !ret ? "deasserted" : "asserted",
> + c_state ? "deasserted" : "asserted",
> + halted ? "halted" : "unhalted");
> + ret = -EINVAL;
> + }
> +
> + /* fixup TCMs, cluster & core flags to actual values in IPC-only mode */
> + if (ret > 0) {
> + if (core == core0)
> + cluster->mode = mode;
> + core->atcm_enable = atcm_enable;
> + core->btcm_enable = btcm_enable;
> + core->loczrama = loczrama;
> + core->mem[0].dev_addr = loczrama ? 0 : K3_R5_TCM_DEV_ADDR;
> + core->mem[1].dev_addr = loczrama ? K3_R5_TCM_DEV_ADDR : 0;
> + }
> +
> + return ret;
> +}
> +
> static int k3_r5_cluster_rproc_init(struct platform_device *pdev)
> {
> struct k3_r5_cluster *cluster = platform_get_drvdata(pdev);
> @@ -1054,6 +1262,12 @@ static int k3_r5_cluster_rproc_init(struct platform_device *pdev)
> kproc->rproc = rproc;
> core->rproc = rproc;
>
> + ret = k3_r5_rproc_configure_mode(kproc);
> + if (ret < 0)
> + goto err_config;
> + if (ret)
> + goto init_rmem;
> +
> ret = k3_r5_rproc_configure(kproc);
> if (ret) {
> dev_err(dev, "initial configure failed, ret = %d\n",
> @@ -1061,6 +1275,7 @@ static int k3_r5_cluster_rproc_init(struct platform_device *pdev)
> goto err_config;
> }
>
> +init_rmem:
> k3_r5_adjust_tcm_sizes(kproc);
>
> ret = k3_r5_reserved_mem_init(kproc);
> --
> 2.30.1