[PATCH v5 8/8] firmware: arm_scpi: Support unidirectional mailbox channels

Samuel Holland
2019-12-15T04:25:11Z

Some mailbox controllers have only unidirectional channels, so we need a
pair of them for each SCPI channel. If a mbox-names property is present,
look for "rx" and "tx" mbox channels; otherwise, the existing behavior
is preserved, and a single mbox channel is used for each SCPI channel.

Note that since the mailbox framework only supports a single phandle
with each name (mbox_request_channel_byname always returns the first
one), this new mode only supports a single SCPI channel.

Signed-off-by: Samuel Holland <samuel@sholland.org>
---
drivers/firmware/arm_scpi.c | 58 +++++++++++++++++++++++++++++--------
1 file changed, 46 insertions(+), 12 deletions(-)

diff --git a/drivers/firmware/arm_scpi.c b/drivers/firmware/arm_scpi.c
index a80c331c3a6e..36ff9dd8d0fa 100644
--- a/drivers/firmware/arm_scpi.c
+++ b/drivers/firmware/arm_scpi.c
@@ -231,7 +231,8 @@ struct scpi_xfer {

struct scpi_chan {
struct mbox_client cl;
- struct mbox_chan *chan;
+ struct mbox_chan *rx_chan;
+ struct mbox_chan *tx_chan;
void __iomem *tx_payload;
void __iomem *rx_payload;
struct list_head rx_pending;
@@ -505,7 +506,7 @@ static int scpi_send_message(u8 idx, void *tx_buf, unsigned int tx_len,
msg->rx_len = rx_len;
reinit_completion(&msg->done);

- ret = mbox_send_message(scpi_chan->chan, msg);
+ ret = mbox_send_message(scpi_chan->tx_chan, msg);
if (ret < 0 || !rx_buf)
goto out;

@@ -854,8 +855,13 @@ static void scpi_free_channels(void *data)
struct scpi_drvinfo *info = data;
int i;

- for (i = 0; i < info->num_chans; i++)
- mbox_free_channel(info->channels[i].chan);
+ for (i = 0; i < info->num_chans; i++) {
+ struct scpi_chan *pchan = &info->channels[i];
+
+ if (pchan->tx_chan != pchan->rx_chan)
+ mbox_free_channel(pchan->tx_chan);
+ mbox_free_channel(pchan->rx_chan);
+ }
}

static int scpi_remove(struct platform_device *pdev)
@@ -903,6 +909,7 @@ static int scpi_probe(struct platform_device *pdev)
struct resource res;
struct device *dev = &pdev->dev;
struct device_node *np = dev->of_node;
+ bool use_mbox_names = false;

scpi_info = devm_kzalloc(dev, sizeof(*scpi_info), GFP_KERNEL);
if (!scpi_info)
@@ -916,6 +923,14 @@ static int scpi_probe(struct platform_device *pdev)
dev_err(dev, "no mboxes property in '%pOF'\n", np);
return -ENODEV;
}
+ if (of_get_property(dev->of_node, "mbox-names", NULL)) {
+ use_mbox_names = true;
+ if (count != 2) {
+ dev_err(dev, "need exactly 2 mboxes with mbox-names\n");
+ return -ENODEV;
+ }
+ count /= 2;
+ }

scpi_info->channels = devm_kcalloc(dev, count, sizeof(struct scpi_chan),
GFP_KERNEL);
@@ -961,15 +976,34 @@ static int scpi_probe(struct platform_device *pdev)
mutex_init(&pchan->xfers_lock);

ret = scpi_alloc_xfer_list(dev, pchan);
- if (!ret) {
- pchan->chan = mbox_request_channel(cl, idx);
- if (!IS_ERR(pchan->chan))
- continue;
- ret = PTR_ERR(pchan->chan);
- if (ret != -EPROBE_DEFER)
- dev_err(dev, "failed to get channel%d err %d\n",
- idx, ret);
+ if (ret)
+ return ret;
+
+ if (use_mbox_names) {
+ pchan->rx_chan = mbox_request_channel_byname(cl, "rx");
+ if (IS_ERR(pchan->rx_chan)) {
+ ret = PTR_ERR(pchan->rx_chan);
+ goto fail;
+ }
+ pchan->tx_chan = mbox_request_channel_byname(cl, "tx");
+ if (IS_ERR(pchan->rx_chan)) {
+ ret = PTR_ERR(pchan->tx_chan);
+ goto fail;
+ }
+ } else {
+ pchan->rx_chan = mbox_request_channel(cl, idx);
+ if (IS_ERR(pchan->rx_chan)) {
+ ret = PTR_ERR(pchan->rx_chan);
+ goto fail;
+ }
+ pchan->tx_chan = pchan->rx_chan;
}
+ continue;
+
+fail:
+ if (ret != -EPROBE_DEFER)
+ dev_err(dev, "failed to get channel%d err %d\n",
+ idx, ret);
return ret;
}

--
2.23.0