linux-kernel - Re: [PATCH] rpmsg: qcom_smd: Access APCS through mailbox framework

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Message-ID: <cad92480-7f12-b9f3-a3d1-0a4208849d35@codeaurora.org>
Date:   Wed, 6 Dec 2017 17:38:02 +0530
From:   Jitendra Sharma <shajit@...eaurora.org>
To:     Bjorn Andersson <bjorn.andersson@...aro.org>,
        Ohad Ben-Cohen <ohad@...ery.com>
Cc:     linux-remoteproc@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-msm@...r.kernel.org
Subject: Re: [PATCH] rpmsg: qcom_smd: Access APCS through mailbox framework

Hi Bjorn,


On 11/16/2017 12:38 PM, Bjorn Andersson wrote:
> Attempt to acquire the APCS IPC through the mailbox framework and fall
> back to the old syscon based approach, to allow us to move away from
> using the syscon.
>
> Signed-off-by: Bjorn Andersson <bjorn.andersson@...aro.org>
> ---
>   drivers/rpmsg/qcom_smd.c | 62 +++++++++++++++++++++++++++++++++---------------
>   1 file changed, 43 insertions(+), 19 deletions(-)
>
> diff --git a/drivers/rpmsg/qcom_smd.c b/drivers/rpmsg/qcom_smd.c
> index b01774e9fac0..ef2a526ebc8f 100644
> --- a/drivers/rpmsg/qcom_smd.c
> +++ b/drivers/rpmsg/qcom_smd.c
> @@ -14,6 +14,7 @@
>   
>   #include <linux/interrupt.h>
>   #include <linux/io.h>
> +#include <linux/mailbox_client.h>
>   #include <linux/mfd/syscon.h>
>   #include <linux/module.h>
>   #include <linux/of_irq.h>
> @@ -107,6 +108,8 @@ static const struct {
>    * @ipc_regmap:		regmap handle holding the outgoing ipc register
>    * @ipc_offset:		offset within @ipc_regmap of the register for ipc
>    * @ipc_bit:		bit in the register at @ipc_offset of @ipc_regmap
> + * @mbox_client:	mailbox client handle
> + * @mbox_chan:		apcs ipc mailbox channel handle
>    * @channels:		list of all channels detected on this edge
>    * @channels_lock:	guard for modifications of @channels
>    * @allocated:		array of bitmaps representing already allocated channels
> @@ -129,6 +132,9 @@ struct qcom_smd_edge {
>   	int ipc_offset;
>   	int ipc_bit;
>   
> +	struct mbox_client mbox_client;
> +	struct mbox_chan *mbox_chan;
> +
>   	struct list_head channels;
>   	spinlock_t channels_lock;
>   
> @@ -365,7 +371,12 @@ static void qcom_smd_signal_channel(struct qcom_smd_channel *channel)
>   {
>   	struct qcom_smd_edge *edge = channel->edge;
>   
> -	regmap_write(edge->ipc_regmap, edge->ipc_offset, BIT(edge->ipc_bit));
> +	if (edge->mbox_chan) {
> +		mbox_send_message(edge->mbox_chan, NULL);
mbox_send_message could fail. So return value should be checked
> +		mbox_client_txdone(edge->mbox_chan, 0);
> +	} else {
> +		regmap_write(edge->ipc_regmap, edge->ipc_offset, BIT(edge->ipc_bit));
> +	}
>   }
>   
>   /*
> @@ -1268,27 +1279,37 @@ static int qcom_smd_parse_edge(struct device *dev,
>   	key = "qcom,remote-pid";
>   	of_property_read_u32(node, key, &edge->remote_pid);
>   
> -	syscon_np = of_parse_phandle(node, "qcom,ipc", 0);
> -	if (!syscon_np) {
> -		dev_err(dev, "no qcom,ipc node\n");
> -		return -ENODEV;
> -	}
> +	edge->mbox_client.dev = dev;
> +	edge->mbox_client.knows_txdone = true;
> +	edge->mbox_chan = mbox_request_channel(&edge->mbox_client, 0);
> +	if (IS_ERR(edge->mbox_chan)) {
> +		if (PTR_ERR(edge->mbox_chan) != -ENODEV)
> +			return PTR_ERR(edge->mbox_chan);
>   
> -	edge->ipc_regmap = syscon_node_to_regmap(syscon_np);
> -	if (IS_ERR(edge->ipc_regmap))
> -		return PTR_ERR(edge->ipc_regmap);
> +		edge->mbox_chan = NULL;
>   
> -	key = "qcom,ipc";
> -	ret = of_property_read_u32_index(node, key, 1, &edge->ipc_offset);
> -	if (ret < 0) {
> -		dev_err(dev, "no offset in %s\n", key);
> -		return -EINVAL;
> -	}
> +		syscon_np = of_parse_phandle(node, "qcom,ipc", 0);
> +		if (!syscon_np) {
> +			dev_err(dev, "no qcom,ipc node\n");
> +			return -ENODEV;
> +		}
>   
> -	ret = of_property_read_u32_index(node, key, 2, &edge->ipc_bit);
> -	if (ret < 0) {
> -		dev_err(dev, "no bit in %s\n", key);
> -		return -EINVAL;
> +		edge->ipc_regmap = syscon_node_to_regmap(syscon_np);
> +		if (IS_ERR(edge->ipc_regmap))
> +			return PTR_ERR(edge->ipc_regmap);
> +
> +		key = "qcom,ipc";
> +		ret = of_property_read_u32_index(node, key, 1, &edge->ipc_offset);
> +		if (ret < 0) {
> +			dev_err(dev, "no offset in %s\n", key);
> +			return -EINVAL;
> +		}
> +
> +		ret = of_property_read_u32_index(node, key, 2, &edge->ipc_bit);
> +		if (ret < 0) {
> +			dev_err(dev, "no bit in %s\n", key);
> +			return -EINVAL;
> +		}
>   	}
>   
>   	ret = of_property_read_string(node, "label", &edge->name);
> @@ -1394,6 +1415,8 @@ struct qcom_smd_edge *qcom_smd_register_edge(struct device *parent,
>   	return edge;
>   
>   unregister_dev:
> +	if (!IS_ERR_OR_NULL(edge->mbox_chan))
> +		mbox_free_channel(edge->mbox_chan);
>   	put_device(&edge->dev);
>   	return ERR_PTR(ret);
>   }
> @@ -1422,6 +1445,7 @@ int qcom_smd_unregister_edge(struct qcom_smd_edge *edge)
>   	if (ret)
>   		dev_warn(&edge->dev, "can't remove smd device: %d\n", ret);
>   
> +	mbox_free_channel(edge->mbox_chan);
>   	device_unregister(&edge->dev);
>   
>   	return 0;