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

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Date:   Wed, 23 Mar 2022 12:50:14 +0530
From:   Deepak Kumar Singh <quic_deesin@...cinc.com>
To:     Bjorn Andersson <bjorn.andersson@...aro.org>
CC:     <swboyd@...omium.org>, <quic_clew@...cinc.com>,
        <mathieu.poirier@...aro.org>, <linux-kernel@...r.kernel.org>,
        <linux-arm-msm@...r.kernel.org>,
        <linux-remoteproc@...r.kernel.org>,
        "Andy Gross" <agross@...nel.org>, Ohad Ben-Cohen <ohad@...ery.com>
Subject: Re: [PATCH V2 2/3] rpmsg: glink: Add support to handle signals
 command


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@...cinc.com>
> 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@...cinc.com>
>> ---
>>   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
>>