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Message-ID: <20251110150825.3548819-1-andrea.tomassetti@sipearl.com>
Date: Mon, 10 Nov 2025 16:08:21 +0100
From: Andrea Tomassetti <andrea.tomassetti@...earl.com>
To: <sudeep.holla@....com>, <jassisinghbrar@...il.com>, <rafael@...nel.org>
CC: Andrea Tomassetti <andrea.tomassetti@...earl.com>, <lenb@...nel.org>,
<linux-acpi@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
<olivierdautricourt@...il.com>, Thibault Cantori
<thibault.cantori@...earl.com>, Olivier Dautricourt
<olivier.dautricourt@...earl.com>
Subject: [PATCH] mailbox: pcc: support polling mode when there is no platform IRQ
The goal is to allow clients to submit a message in both irq and polling
mode of the pcc mailbox. The ACPI specification does not require a
platform irq for pcc channels. Let's implement the case where it is not
available.
peek_data is mapped to pcc_mbox_error_check_and_clear, so that it
returns true if no error occurred while the platform processed last
message, and therefore clients can fetch response data provided by the
platform.
Tested-by: Thibault Cantori <thibault.cantori@...earl.com>
Co-developed-by: Olivier Dautricourt <olivier.dautricourt@...earl.com>
Signed-off-by: Olivier Dautricourt <olivier.dautricourt@...earl.com>
Signed-off-by: Andrea Tomassetti <andrea.tomassetti@...earl.com>
---
drivers/acpi/acpi_pcc.c | 77 ++++++++++++++++++++++++++++-------------
drivers/mailbox/pcc.c | 12 ++++++-
2 files changed, 63 insertions(+), 26 deletions(-)
diff --git a/drivers/acpi/acpi_pcc.c b/drivers/acpi/acpi_pcc.c
index 97064e943768..ef5d7eae150b 100644
--- a/drivers/acpi/acpi_pcc.c
+++ b/drivers/acpi/acpi_pcc.c
@@ -51,7 +51,6 @@ acpi_pcc_address_space_setup(acpi_handle region_handle, u32 function,
{
struct pcc_data *data;
struct acpi_pcc_info *ctx = handler_context;
- struct pcc_mbox_chan *pcc_chan;
static acpi_status ret;
data = kzalloc(sizeof(*data), GFP_KERNEL);
@@ -59,7 +58,7 @@ acpi_pcc_address_space_setup(acpi_handle region_handle, u32 function,
return AE_NO_MEMORY;
data->cl.rx_callback = pcc_rx_callback;
- data->cl.knows_txdone = true;
+ data->cl.knows_txdone = false;
data->ctx.length = ctx->length;
data->ctx.subspace_id = ctx->subspace_id;
data->ctx.internal_buffer = ctx->internal_buffer;
@@ -73,61 +72,89 @@ acpi_pcc_address_space_setup(acpi_handle region_handle, u32 function,
goto err_free_data;
}
- pcc_chan = data->pcc_chan;
- if (!pcc_chan->mchan->mbox->txdone_irq) {
- pr_err("This channel-%d does not support interrupt.\n",
- ctx->subspace_id);
- ret = AE_SUPPORT;
- goto err_free_channel;
- }
-
*region_context = data;
return AE_OK;
-err_free_channel:
- pcc_mbox_free_channel(data->pcc_chan);
err_free_data:
kfree(data);
return ret;
}
+static acpi_status
+acpi_pcc_send_msg_polling(struct pcc_data *data)
+{
+ int ret;
+
+ ret = mbox_send_message(data->pcc_chan->mchan, data->pcc_chan->shmem);
+ if (ret == -ETIME) {
+ pr_err("PCC command executed timeout!\n");
+ return AE_TIME;
+ }
+
+ if (ret < 0)
+ return AE_ERROR;
+
+ if (!mbox_client_peek_data(data->pcc_chan->mchan))
+ return AE_ERROR;
+
+ return AE_OK;
+}
+
+static acpi_status
+acpi_pcc_send_msg_irq(struct pcc_data *data)
+{
+ int ret;
+
+ ret = mbox_send_message(data->pcc_chan->mchan, NULL);
+ if (ret < 0)
+ return AE_ERROR;
+
+ ret = wait_for_completion_timeout(&data->done,
+ usecs_to_jiffies(data->cl.tx_tout * USEC_PER_MSEC));
+ if (ret == 0) {
+ pr_err("PCC command executed timeout!\n");
+ return AE_TIME;
+ }
+
+ mbox_chan_txdone(data->pcc_chan->mchan, ret);
+
+ return AE_OK;
+}
+
static acpi_status
acpi_pcc_address_space_handler(u32 function, acpi_physical_address addr,
u32 bits, acpi_integer *value,
void *handler_context, void *region_context)
{
- int ret;
+ acpi_status ret;
struct pcc_data *data = region_context;
u64 usecs_lat;
+ bool use_polling = data->pcc_chan->mchan->mbox->txdone_poll;
reinit_completion(&data->done);
/* Write to Shared Memory */
memcpy_toio(data->pcc_chan->shmem, (void *)value, data->ctx.length);
- ret = mbox_send_message(data->pcc_chan->mchan, NULL);
- if (ret < 0)
- return AE_ERROR;
-
/*
* pcc_chan->latency is just a Nominal value. In reality the remote
* processor could be much slower to reply. So add an arbitrary
* amount of wait on top of Nominal.
*/
usecs_lat = PCC_CMD_WAIT_RETRIES_NUM * data->pcc_chan->latency;
- ret = wait_for_completion_timeout(&data->done,
- usecs_to_jiffies(usecs_lat));
- if (ret == 0) {
- pr_err("PCC command executed timeout!\n");
- return AE_TIME;
- }
- mbox_chan_txdone(data->pcc_chan->mchan, ret);
+ data->cl.tx_block = use_polling;
+ data->cl.tx_tout = usecs_lat / USEC_PER_MSEC;
+
+ if (use_polling)
+ ret = acpi_pcc_send_msg_polling(data);
+ else
+ ret = acpi_pcc_send_msg_irq(data);
memcpy_fromio(value, data->pcc_chan->shmem, data->ctx.length);
- return AE_OK;
+ return ret;
}
void __init acpi_init_pcc(void)
diff --git a/drivers/mailbox/pcc.c b/drivers/mailbox/pcc.c
index 0a00719b2482..e4e744669f81 100644
--- a/drivers/mailbox/pcc.c
+++ b/drivers/mailbox/pcc.c
@@ -579,11 +579,17 @@ static void pcc_shutdown(struct mbox_chan *chan)
devm_free_irq(chan->mbox->dev, pchan->plat_irq, chan);
}
+static bool pcc_peek_data(struct mbox_chan *chan)
+{
+ return pcc_mbox_error_check_and_clear(chan->con_priv) == 0;
+}
+
static const struct mbox_chan_ops pcc_chan_ops = {
.send_data = pcc_send_data,
.startup = pcc_startup,
.shutdown = pcc_shutdown,
.last_tx_done = pcc_last_tx_done,
+ .peek_data = pcc_peek_data,
};
/**
@@ -877,8 +883,12 @@ static int pcc_mbox_probe(struct platform_device *pdev)
(unsigned long) pcct_tbl + sizeof(struct acpi_table_pcct));
acpi_pcct_tbl = (struct acpi_table_pcct *) pcct_tbl;
- if (acpi_pcct_tbl->flags & ACPI_PCCT_DOORBELL)
+ if (acpi_pcct_tbl->flags & ACPI_PCCT_DOORBELL) {
pcc_mbox_ctrl->txdone_irq = true;
+ } else {
+ pcc_mbox_ctrl->txdone_poll = true;
+ pcc_mbox_ctrl->txpoll_period = 1;
+ }
for (i = 0; i < count; i++) {
struct pcc_chan_info *pchan = chan_info + i;
--
2.25.0
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