The mailbox framework controls the transmission queue and requires
either its controller implementations or clients to run the state
machine for the Tx queue. The OMAP mailbox controller uses a Tx-ready
interrupt as the equivalent of a Tx-done interrupt to run this Tx
queue state-machine.
The WkupM3 processor on AM33xx and AM43xx SoCs is used to offload
certain PM tasks, like doing the necessary operations for Device
PM suspend/resume or for entering lower c-states during cpuidle.
The CPUIdle on AM33xx requires the messages to be sent without
having to trigger the Tx-ready interrupts, as the interrupt
would immediately terminate the CPUIdle operation. Support for
this has been added by introducing a DT quirk, "ti,mbox-send-noirq"
and using it to modify the normal OMAP mailbox controller behavior
on the sub-mailboxes used to communicate with the WkupM3 remote
processor. This also requires the wkup_m3_ipc driver to adjust
its mailbox usage logic to run the Tx state machine.
NOTE:
- AM43xx does not communicate with WkupM3 for CPU Idle, so is
not affected by this behavior. But, it uses the same IPC driver
for PM suspend/resume functionality, so requires the quirk as
well, because of changes to the common wkup_m3_ipc driver.
Signed-off-by: Dave Gerlach <d-gerlach@xxxxxx>
[s-anna@xxxxxx: revise logic and update comments/patch description]
Signed-off-by: Suman Anna <s-anna@xxxxxx>
---
v2->v3: Unchanged.
.../devicetree/bindings/mailbox/omap-mailbox.txt | 8 ++++
drivers/mailbox/omap-mailbox.c | 49 ++++++++++++++++++++--
2 files changed, 53 insertions(+), 4 deletions(-)
diff --git a/Documentation/devicetree/bindings/mailbox/omap-mailbox.txt b/Documentation/devicetree/bindings/mailbox/omap-mailbox.txt
index d1a0433..9b40c49 100644
--- a/Documentation/devicetree/bindings/mailbox/omap-mailbox.txt
+++ b/Documentation/devicetree/bindings/mailbox/omap-mailbox.txt
@@ -75,6 +75,14 @@ data that represent the following:
Cell #3 (usr_id) - mailbox user id for identifying the interrupt line
associated with generating a tx/rx fifo interrupt.
+Optional Properties:
+--------------------
+- ti,mbox-send-noirq: Quirk flag to allow the client user of this sub-mailbox
+ to send messages without triggering a Tx ready interrupt,
+ and to control the Tx ticker. Should be used only on
+ sub-mailboxes used to communicate with WkupM3 remote
+ processor on AM33xx/AM43xx SoCs.
+
Mailbox Users:
==============
A device needing to communicate with a target processor device should specify
diff --git a/drivers/mailbox/omap-mailbox.c b/drivers/mailbox/omap-mailbox.c
index a3dbfd9..b7f636f 100644
--- a/drivers/mailbox/omap-mailbox.c
+++ b/drivers/mailbox/omap-mailbox.c
@@ -38,6 +38,8 @@
#include <linux/mailbox_controller.h>
#include <linux/mailbox_client.h>
+#include "mailbox.h"
+
#define MAILBOX_REVISION 0x000
#define MAILBOX_MESSAGE(m) (0x040 + 4 * (m))
#define MAILBOX_FIFOSTATUS(m) (0x080 + 4 * (m))
@@ -106,6 +108,7 @@ struct omap_mbox_fifo_info {
int rx_irq;
const char *name;
+ bool send_no_irq;
};
struct omap_mbox {
@@ -119,6 +122,7 @@ struct omap_mbox {
u32 ctx[OMAP4_MBOX_NR_REGS];
u32 intr_type;
struct mbox_chan *chan;
+ bool send_no_irq;
};
/* global variables for the mailbox devices */
@@ -418,6 +422,9 @@ static int omap_mbox_startup(struct omap_mbox *mbox)
goto fail_request_irq;
}
+ if (mbox->send_no_irq)
+ mbox->chan->txdone_method = TXDONE_BY_ACK;
+
_omap_mbox_enable_irq(mbox, IRQ_RX);
return 0;
@@ -586,13 +593,27 @@ static void omap_mbox_chan_shutdown(struct mbox_chan *chan)
mutex_unlock(&mdev->cfg_lock);
}
-static int omap_mbox_chan_send_data(struct mbox_chan *chan, void *data)
+static int omap_mbox_chan_send_noirq(struct omap_mbox *mbox, void *data)
{
- struct omap_mbox *mbox = mbox_chan_to_omap_mbox(chan);
int ret = -EBUSY;
- if (!mbox)
- return -EINVAL;
+ if (!mbox_fifo_full(mbox)) {
+ _omap_mbox_enable_irq(mbox, IRQ_RX);
+ mbox_fifo_write(mbox, (mbox_msg_t)data);
+ ret = 0;
+ _omap_mbox_disable_irq(mbox, IRQ_RX);
+
+ /* we must read and ack the interrupt directly from here */
+ mbox_fifo_read(mbox);
+ ack_mbox_irq(mbox, IRQ_RX);
+ }
+
+ return ret;
+}
+
+static int omap_mbox_chan_send(struct omap_mbox *mbox, void *data)
+{
+ int ret = -EBUSY;
if (!mbox_fifo_full(mbox)) {
mbox_fifo_write(mbox, (mbox_msg_t)data);
@@ -604,6 +625,22 @@ static int omap_mbox_chan_send_data(struct mbox_chan *chan, void *data)
return ret;
}
+static int omap_mbox_chan_send_data(struct mbox_chan *chan, void *data)
+{
+ struct omap_mbox *mbox = mbox_chan_to_omap_mbox(chan);
+ int ret;
+
+ if (!mbox)
+ return -EINVAL;
+
+ if (mbox->send_no_irq)
+ ret = omap_mbox_chan_send_noirq(mbox, data);
+ else
+ ret = omap_mbox_chan_send(mbox, data);
+
+ return ret;
+}
+
static const struct mbox_chan_ops omap_mbox_chan_ops = {
.startup = omap_mbox_chan_startup,
.send_data = omap_mbox_chan_send_data,
@@ -732,6 +769,9 @@ static int omap_mbox_probe(struct platform_device *pdev)
finfo->rx_usr = tmp[2];
finfo->name = child->name;
+
+ if (of_find_property(child, "ti,mbox-send-noirq", NULL))
+ finfo->send_no_irq = true;
} else {
finfo->tx_id = info->tx_id;
finfo->rx_id = info->rx_id;
@@ -791,6 +831,7 @@ static int omap_mbox_probe(struct platform_device *pdev)
fifo->irqstatus = MAILBOX_IRQSTATUS(intr_type, finfo->rx_usr);
fifo->irqdisable = MAILBOX_IRQDISABLE(intr_type, finfo->rx_usr);
+ mbox->send_no_irq = finfo->send_no_irq;
mbox->intr_type = intr_type;
mbox->parent = mdev;
--
2.4.6
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