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SubjectRE: [PATCH V2 1/2] mailbox: imx: support SCU channel type
Date
Hi Oleksij,

> Subject: Re: [PATCH V2 1/2] mailbox: imx: support SCU channel type
>
> Hi,
>
> On 25.02.20 04:17, peng.fan@nxp.com wrote:
> > From: Peng Fan <peng.fan@nxp.com>
> >
> > Per i.MX8QXP Reference mannual, Chapter "12.9.2.3.2 Messaging
> Examples",
> > Passing short messages: Transmit register(s) can be used to pass
> > short messages from one to four words in length. For example, when
> > a four-word message is desired, only one of the registers needs to
> > have its corresponding interrupt enable bit set at the receiver side;
> > the message’s first three words are written to the registers whose
> > interrupt is masked, and the fourth word is written to the other
> > register (which triggers an interrupt at the receiver side).
> >
> > i.MX8/8X SCU firmware IPC is an implementation of passing short
> > messages. But current imx-mailbox driver only support one word
> > message, i.MX8/8X linux side firmware has to request four TX and four
> > RX to support IPC to SCU firmware. This is low efficent and more
> > interrupts triggered compared with one TX and one RX.
> >
> > To make SCU channel type work,
> > - parse the size of msg.
> > - Only enable TR0/RR0 interrupt for transmit/receive message.
> >
> > Signed-off-by: Peng Fan <peng.fan@nxp.com>
> > ---
> > drivers/mailbox/imx-mailbox.c | 46
> +++++++++++++++++++++++++++++++++++++++----
> > 1 file changed, 42 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/mailbox/imx-mailbox.c
> > b/drivers/mailbox/imx-mailbox.c index 2cdcdc5f1119..0b4a33254114
> > 100644
> > --- a/drivers/mailbox/imx-mailbox.c
> > +++ b/drivers/mailbox/imx-mailbox.c
> > @@ -4,6 +4,7 @@
> > */
> >
> > #include <linux/clk.h>
> > +#include <linux/firmware/imx/ipc.h>
> > #include <linux/interrupt.h>
> > #include <linux/io.h>
> > #include <linux/kernel.h>
> > @@ -65,8 +66,14 @@ struct imx_mu_priv {
> > int irq;
> >
> > bool side_b;
> > + bool scu;
> > };
> >
> > +struct imx_sc_rpc_msg_max {
> > + struct imx_sc_rpc_msg hdr;
> > + u32 data[7];
> > +} __packed __aligned(4);;
> > +
> > static const struct imx_mu_dcfg imx_mu_cfg_imx6sx = {
> > .xTR = {0x0, 0x4, 0x8, 0xc},
> > .xRR = {0x10, 0x14, 0x18, 0x1c},
> > @@ -123,7 +130,10 @@ static irqreturn_t imx_mu_isr(int irq, void *p)
> > struct mbox_chan *chan = p;
> > struct imx_mu_priv *priv = to_imx_mu_priv(chan->mbox);
> > struct imx_mu_con_priv *cp = chan->con_priv;
> > + struct imx_sc_rpc_msg_max msg;
> > + u32 *p_msg = (u32 *)&msg;
> > u32 val, ctrl, dat;
> > + int i;
> >
> > ctrl = imx_mu_read(priv, priv->dcfg->xCR);
> > val = imx_mu_read(priv, priv->dcfg->xSR); @@ -152,8 +162,19 @@
> > static irqreturn_t imx_mu_isr(int irq, void *p)
> > imx_mu_xcr_rmw(priv, 0, IMX_MU_xCR_TIEn(cp->idx));
> > mbox_chan_txdone(chan, 0);
> > } else if (val == IMX_MU_xSR_RFn(cp->idx)) {
> > - dat = imx_mu_read(priv, priv->dcfg->xRR[cp->idx]);
> > - mbox_chan_received_data(chan, (void *)&dat);
> > + if (!priv->scu) {
> > + dat = imx_mu_read(priv, priv->dcfg->xRR[cp->idx]);
> > + mbox_chan_received_data(chan, (void *)&dat);
> > + } else {
> > + imx_mu_xcr_rmw(priv, 0, IMX_MU_xCR_RIEn(0));
> > + *p_msg++ = imx_mu_read(priv, priv->dcfg->xRR[0]);
> > + for (i = 1; i < msg.hdr.size; i++) {
> > + *p_msg++ = imx_mu_read(priv,
> > + priv->dcfg->xRR[i % 4]);
> > + }
> > + imx_mu_xcr_rmw(priv, IMX_MU_xCR_RIEn(0), 0);
> > + mbox_chan_received_data(chan, (void *)&msg);
> > + }
> > } else if (val == IMX_MU_xSR_GIPn(cp->idx)) {
> > imx_mu_write(priv, IMX_MU_xSR_GIPn(cp->idx),
> priv->dcfg->xSR);
> > mbox_chan_received_data(chan, NULL); @@ -169,11 +190,20
> @@ static
> > int imx_mu_send_data(struct mbox_chan *chan, void *data)
> > {
> > struct imx_mu_priv *priv = to_imx_mu_priv(chan->mbox);
> > struct imx_mu_con_priv *cp = chan->con_priv;
> > + struct imx_sc_rpc_msg_max *msg = data;
> > u32 *arg = data;
> > + int i;
> >
> > switch (cp->type) {
> > case IMX_MU_TYPE_TX:
> > - imx_mu_write(priv, *arg, priv->dcfg->xTR[cp->idx]);
> > + if (priv->scu) {
> > + for (i = 0; i < msg->hdr.size; i++) {
> > + imx_mu_write(priv, *arg++,
> > + priv->dcfg->xTR[i % 4]);
> > + }
> > + } else {
> > + imx_mu_write(priv, *arg, priv->dcfg->xTR[cp->idx]);
> > + }
> > imx_mu_xcr_rmw(priv, IMX_MU_xCR_TIEn(cp->idx), 0);
> > break;
> > case IMX_MU_TYPE_TXDB:
> > @@ -259,6 +289,7 @@ static const struct mbox_chan_ops imx_mu_ops = {
> > static struct mbox_chan * imx_mu_xlate(struct mbox_controller *mbox,
> > const struct of_phandle_args *sp)
> > {
> > + struct imx_mu_priv *priv = to_imx_mu_priv(mbox);
> > u32 type, idx, chan;
> >
> > if (sp->args_count != 2) {
> > @@ -270,7 +301,9 @@ static struct mbox_chan * imx_mu_xlate(struct
> mbox_controller *mbox,
> > idx = sp->args[1]; /* index */
> > chan = type * 4 + idx;
> >
> > - if (chan >= mbox->num_chans) {
> > + /* For TX/RX SCU, only one channel supported */
> > + if ((chan >= mbox->num_chans) ||
> > + (priv->scu && type < 1 && idx >= 1)) {
> > dev_err(mbox->dev, "Not supported channel number: %d.
> (type: %d, idx: %d)\n", chan, type, idx);
> > return ERR_PTR(-EINVAL);
> > }
> > @@ -341,6 +374,11 @@ static int imx_mu_probe(struct platform_device
> *pdev)
> > }
> >
> > priv->side_b = of_property_read_bool(np, "fsl,mu-side-b");
> > + np = of_find_compatible_node(NULL, NULL, "fsl,imx-scu");
>
> This will configure every MU on the SoC as SCU, even it is not communicating
> with it.
>
> > + if (np) {
> > + priv->scu = true;
> > + of_node_put(np);
> > + }
> >
>
> Please take a look at drivers/remoteproc/imx_rproc.c especially the use of
> struct imx_rproc_dcfg.
> Introduce simialr struct in the imx-mailbox.c

ok, I'll introduce something like that.

>
> It will be some thing like:
> struct imx_mu_dcfg {
> unsigned int chans; /* number of supported channels */
> int (*tx)(struct imx_mu_priv *priv, struct imx_mu_con_priv *cp);
> int (*rx)(struct imx_mu_priv *priv, struct imx_mu_con_priv *cp); }
>
> Define functions for generic tx/rx. And for SCU specific tx/rx. Please, add
> sanity check in to SCU specific functions. In current implementation an error
> on SCU side will couse stack corruption on Linux side.

We expect SCU not crash or have error behavior. Anyway I'll add check in Linux
side.

>
> Use compatible string (some thing like fsl,imx8-mu-scu) to detect proper
> metrics of new device.

ok. Thanks for your suggestions.

Thanks,
Peng.

>
> Kind regards,
> Oleksij Rempel
>
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