Re: [PATCH V2 2/3] rpmsg: glink: Add support to handle signals command

[Deepak Kumar Singh]

On 3/12/2022 2:39 AM, Bjorn Andersson wrote:
> On Tue 18 Jan 13:43 CST 2022, Deepak Kumar Singh wrote:
>
> > Remote peripherals send signal notifications over glink with commandID 15.
> >
> > Add support to send and receive the signal command and convert the signals
> > from NATIVE to TIOCM while receiving and vice versa while sending.
> >
> > Signed-off-by: Chris Lew <quic_clew@xxxxxxxxxxx>
> Co-developed-by: seems appropriate here, or you need to ensure the
> author remains Chris, as his S-o-b comes first.
>
> > Signed-off-by: Deepak Kumar Singh <quic_deesin@xxxxxxxxxxx>
> > ---
> >   drivers/rpmsg/qcom_glink_native.c | 77 +++++++++++++++++++++++++++++++++++++++
> >   1 file changed, 77 insertions(+)
> >
> > diff --git a/drivers/rpmsg/qcom_glink_native.c b/drivers/rpmsg/qcom_glink_native.c
> > index 3f377a7..d673d65 100644
> > --- a/drivers/rpmsg/qcom_glink_native.c
> > +++ b/drivers/rpmsg/qcom_glink_native.c
> > @@ -17,6 +17,7 @@
> >   #include <linux/rpmsg.h>
> >   #include <linux/sizes.h>
> >   #include <linux/slab.h>
> > +#include <linux/termios.h>
> >   #include <linux/workqueue.h>
> >   #include <linux/mailbox_client.h>
> >   
> > @@ -205,9 +206,16 @@ static const struct rpmsg_endpoint_ops glink_endpoint_ops;
> >   #define RPM_CMD_TX_DATA_CONT		12
> >   #define RPM_CMD_READ_NOTIF		13
> >   #define RPM_CMD_RX_DONE_W_REUSE		14
> > +#define RPM_CMD_SIGNALS			15
> >   
> >   #define GLINK_FEATURE_INTENTLESS	BIT(1)
> >   
> > +#define NATIVE_DTR_SIG			BIT(31)
> Seems reasonable to prefix these with GLINK_, perhaps GLINK_SIGNAL_DTR?
>
> > +#define NATIVE_CTS_SIG			BIT(30)
> > +#define NATIVE_CD_SIG			BIT(29)
> > +#define NATIVE_RI_SIG			BIT(28)
> > +#define	SIG_MASK			0x0fff;
> > +
> >   static void qcom_glink_rx_done_work(struct work_struct *work);
> >   
> >   static struct glink_channel *qcom_glink_alloc_channel(struct qcom_glink *glink,
> > @@ -1003,6 +1011,70 @@ static int qcom_glink_rx_open_ack(struct qcom_glink *glink, unsigned int lcid)
> >   	return 0;
> >   }
> >   
> > +/**
> > + * qcom_glink_set_flow_control() - convert a signal cmd to wire format and
> > + * 				   transmit
> > + * @ept:	Rpmsg endpoint for channel.
> > + * @enable:	True/False - enable or disable flow control
> "enable flow control" sounds sufficient (i.e. no need for True/False)
> part.
>
> Regards,
> Bjorn

There are some user space clients which require both flow control on and 
off (DTR high/low).

So i guess true and false both are needed.

> > + *
> > + * Return: 0 on success or standard Linux error code.
> > + */
> > +static int qcom_glink_set_flow_control(struct rpmsg_endpoint *ept, bool enable)
> > +{
> > +	struct glink_channel *channel = to_glink_channel(ept);
> > +	struct qcom_glink *glink = channel->glink;
> > +	struct glink_msg msg;
> > +	u32 sigs;
> > +
> > +	/**
> > +	 * convert signals from TIOCM to NATIVE
> > +	 * sigs = TIOCM_DTR|TIOCM_RTS
> > +	 */
> > +	if (enable)
> > +		sigs |= NATIVE_DTR_SIG | NATIVE_CTS_SIG;
> > +	else
> > +		sigs |= ~(NATIVE_DTR_SIG | NATIVE_CTS_SIG);
> > +
> > +	msg.cmd = cpu_to_le16(RPM_CMD_SIGNALS);
> > +	msg.param1 = cpu_to_le16(channel->lcid);
> > +	msg.param2 = cpu_to_le32(sigs);
> > +
> > +	return qcom_glink_tx(glink, &msg, sizeof(msg), NULL, 0, true);
> > +}
> > +
> > +static int qcom_glink_handle_signals(struct qcom_glink *glink,
> > +				     unsigned int rcid, unsigned int sigs)
> > +{
> > +	struct glink_channel *channel;
> > +	unsigned long flags;
> > +
> > +	spin_lock_irqsave(&glink->idr_lock, flags);
> > +	channel = idr_find(&glink->rcids, rcid);
> > +	spin_unlock_irqrestore(&glink->idr_lock, flags);
> > +	if (!channel) {
> > +		dev_err(glink->dev, "signal for non-existing channel\n");
> > +		return -EINVAL;
> > +	}
> > +
> > +	if (!channel->ept.sig_cb)
> > +		return 0;
> > +
> > +	/* convert signals from NATIVE to TIOCM */
> > +	if (sigs & NATIVE_DTR_SIG)
> > +		sigs |= TIOCM_DSR;
> > +	if (sigs & NATIVE_CTS_SIG)
> > +		sigs |= TIOCM_CTS;
> > +	if (sigs & NATIVE_CD_SIG)
> > +		sigs |= TIOCM_CD;
> > +	if (sigs & NATIVE_RI_SIG)
> > +		sigs |= TIOCM_RI;
> > +	sigs &= SIG_MASK;
> > +
> > +	channel->ept.sig_cb(channel->ept.rpdev, channel->ept.priv, sigs);
> > +
> > +	return 0;
> > +}
> > +
> >   static irqreturn_t qcom_glink_native_intr(int irq, void *data)
> >   {
> >   	struct qcom_glink *glink = data;
> > @@ -1067,6 +1139,10 @@ static irqreturn_t qcom_glink_native_intr(int irq, void *data)
> >   			qcom_glink_handle_intent_req_ack(glink, param1, param2);
> >   			qcom_glink_rx_advance(glink, ALIGN(sizeof(msg), 8));
> >   			break;
> > +		case RPM_CMD_SIGNALS:
> > +			qcom_glink_handle_signals(glink, param1, param2);
> > +			qcom_glink_rx_advance(glink, ALIGN(sizeof(msg), 8));
> > +			break;
> >   		default:
> >   			dev_err(glink->dev, "unhandled rx cmd: %d\n", cmd);
> >   			ret = -EINVAL;
> > @@ -1442,6 +1518,7 @@ static const struct rpmsg_endpoint_ops glink_endpoint_ops = {
> >   	.sendto = qcom_glink_sendto,
> >   	.trysend = qcom_glink_trysend,
> >   	.trysendto = qcom_glink_trysendto,
> > +	.set_flow_control = qcom_glink_set_flow_control,
> >   };
> >   
> >   static void qcom_glink_rpdev_release(struct device *dev)
> > --
> > 2.7.4