On Wed, Mar 25, 2020 at 03:18:39PM -0500, Suman Anna wrote:
> The resets for the DSP processors on K3 SoCs are managed through the
> Power and Sleep Controller (PSC) module. Each DSP typically has two
> resets - a global module reset for powering on the device, and a local
> reset that affects only the CPU while allowing access to the other
> sub-modules within the DSP processor sub-systems.
>
> The C66x DSPs have two levels of internal RAMs that can be used to
> boot from, and the firmware loading into these RAMs require the
> local reset to be asserted with the device powered on/enabled using
> the module reset. Enhance the K3 DSP remoteproc driver to add support
> for loading into the internal RAMs. The local reset is deasserted on
> SoC power-on-reset, so logic has to be added in probe in remoteproc
> mode to balance the remoteproc state-machine.
>
> Note that the local resets are a no-op on C71x cores, and the hardware
> does not supporting loading into its internal RAMs.
>
> Signed-off-by: Suman Anna <[email protected]>
> ---
> drivers/remoteproc/ti_k3_dsp_remoteproc.c | 82 +++++++++++++++++++++++
> 1 file changed, 82 insertions(+)
>
> diff --git a/drivers/remoteproc/ti_k3_dsp_remoteproc.c
> b/drivers/remoteproc/ti_k3_dsp_remoteproc.c
> index fd0d84f46f90..7b712ef74611 100644
> --- a/drivers/remoteproc/ti_k3_dsp_remoteproc.c
> +++ b/drivers/remoteproc/ti_k3_dsp_remoteproc.c
> @@ -175,6 +175,9 @@ static int k3_dsp_rproc_reset(struct k3_dsp_rproc *kproc)
> return ret;
> }
>
> + if (kproc->data->uses_lreset)
> + return ret;
> +
> ret = kproc->ti_sci->ops.dev_ops.put_device(kproc->ti_sci,
> kproc->ti_sci_id);
> if (ret) {
> @@ -192,6 +195,9 @@ static int k3_dsp_rproc_release(struct k3_dsp_rproc
> *kproc)
> struct device *dev = kproc->dev;
> int ret;
>
> + if (kproc->data->uses_lreset)
> + goto lreset;
> +
> ret = kproc->ti_sci->ops.dev_ops.get_device(kproc->ti_sci,
> kproc->ti_sci_id);
> if (ret) {
> @@ -199,6 +205,7 @@ static int k3_dsp_rproc_release(struct k3_dsp_rproc
> *kproc)
> return ret;
> }
>
> +lreset:
> ret = reset_control_deassert(kproc->reset);
> if (ret) {
> dev_err(dev, "local-reset deassert failed, ret = %d\n", ret);
> @@ -210,6 +217,63 @@ static int k3_dsp_rproc_release(struct k3_dsp_rproc
> *kproc)
> return ret;
> }
>
> +/*
> + * The C66x DSP cores have a local reset that affects only the CPU, and a
> + * generic module reset that powers on the device and allows the DSP internal
> + * memories to be accessed while the local reset is asserted. This function
> is
> + * used to release the global reset on C66x DSPs to allow loading into the
> DSP
> + * internal RAMs. The .prepare() ops is invoked by remoteproc core before any
> + * firmware loading, and is followed by the .start() ops after loading to
> + * actually let the C66x DSP cores run. The local reset on C71x cores is a
> + * no-op and the global reset cannot be released on C71x cores until after
> + * the firmware images are loaded, so this function does nothing for C71x
> cores.
> + */
> +static int k3_dsp_rproc_prepare(struct rproc *rproc)
> +{
> + struct k3_dsp_rproc *kproc = rproc->priv;
> + struct device *dev = kproc->dev;
> + int ret;
> +
> + /* local reset is no-op on C71x processors */
> + if (!kproc->data->uses_lreset)
> + return 0;
In k3_dsp_rproc_release() the condition is "if (kproc->data->uses_lreset)" and
here it is the opposite, which did a good job at getting me confused.
Taking a step back, I assume c71 DSPs will have their own k3_dsp_dev_data where
the users_lreset flag will be false. In that case I think it would make the
code easier to understand if the k3_dsp_rproc_ops was declared without the
.prepare and .unprepare. In probe(), if data->uses_lreset is true then
k3_dsp_rproc_prepare() and k3_dsp_rproc_unprepare() are set.
I am done reviewing this set.
Thanks,
Mathieu
> +
> + ret = kproc->ti_sci->ops.dev_ops.get_device(kproc->ti_sci,
> + kproc->ti_sci_id);
> + if (ret)
> + dev_err(dev, "module-reset deassert failed, cannot enable
> internal RAM loading, ret = %d\n",
> + ret);
> +
> + return ret;
> +}
> +
> +/*
> + * This function implements the .unprepare() ops and performs the
> complimentary
> + * operations to that of the .prepare() ops. The function is used to assert
> the
> + * global reset on applicable C66x cores. This completes the second portion
> of
> + * powering down the C66x DSP cores. The cores themselves are only halted in
> the
> + * .stop() callback through the local reset, and the .unprepare() ops is
> invoked
> + * by the remoteproc core after the remoteproc is stopped to balance the
> global
> + * reset.
> + */
> +static int k3_dsp_rproc_unprepare(struct rproc *rproc)
> +{
> + struct k3_dsp_rproc *kproc = rproc->priv;
> + struct device *dev = kproc->dev;
> + int ret;
> +
> + /* local reset is no-op on C71x processors */
> + if (!kproc->data->uses_lreset)
> + return 0;
> +
> + ret = kproc->ti_sci->ops.dev_ops.put_device(kproc->ti_sci,
> + kproc->ti_sci_id);
> + if (ret)
> + dev_err(dev, "module-reset assert failed, ret = %d\n", ret);
> +
> + return ret;
> +}
> +
> /*
> * Power up the DSP remote processor.
> *
> @@ -353,6 +417,8 @@ static void *k3_dsp_rproc_da_to_va(struct rproc *rproc,
> u64 da, size_t len)
> }
>
> static const struct rproc_ops k3_dsp_rproc_ops = {
> + .prepare = k3_dsp_rproc_prepare,
> + .unprepare = k3_dsp_rproc_unprepare,
> .start = k3_dsp_rproc_start,
> .stop = k3_dsp_rproc_stop,
> .kick = k3_dsp_rproc_kick,
> @@ -644,6 +710,22 @@ static int k3_dsp_rproc_probe(struct platform_device
> *pdev)
> goto disable_clk;
> }
>
> + /*
> + * ensure the DSP local reset is asserted to ensure the DSP doesn't
> + * execute bogus code in .prepare() when the module reset is released.
> + */
> + if (data->uses_lreset) {
> + ret = reset_control_status(kproc->reset);
> + if (ret < 0) {
> + dev_err(dev, "failed to get reset status, status =
> %d\n",
> + ret);
> + goto release_mem;
> + } else if (ret == 0) {
> + dev_warn(dev, "local reset is deasserted for device\n");
> + k3_dsp_rproc_reset(kproc);
> + }
> + }
> +
> ret = rproc_add(rproc);
> if (ret) {
> dev_err(dev, "failed to add register device with remoteproc
> core, status = %d\n",
> --
> 2.23.0
>
