linux-kernel - [PATCH 1/2] mailbox: ti-msgmgr: Refactor message read during interrupt handler

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Date:   Wed, 9 Feb 2022 22:16:30 -0600
From:   Dave Gerlach <d-gerlach@...com>
To:     Jassi Brar <jassisinghbrar@...il.com>
CC:     Dave Gerlach <d-gerlach@...com>, <linux-kernel@...r.kernel.org>,
        Suman Anna <s-anna@...com>, Nishanth Menon <nm@...com>,
        Vignesh Raghavendra <vigneshr@...com>
Subject: [PATCH 1/2] mailbox: ti-msgmgr: Refactor message read during interrupt handler

Refactor the portion of code that actually reads received messages from
a queue into its own function, ti_msgmgr_queue_rx_data, that is called
by the interrupt handler instead of reading directly from the handler.

Signed-off-by: Dave Gerlach <d-gerlach@...com>
---
 drivers/mailbox/ti-msgmgr.c | 88 +++++++++++++++++++++----------------
 1 file changed, 49 insertions(+), 39 deletions(-)

diff --git a/drivers/mailbox/ti-msgmgr.c b/drivers/mailbox/ti-msgmgr.c
index efb43b038596..f860cd0c907a 100644
--- a/drivers/mailbox/ti-msgmgr.c
+++ b/drivers/mailbox/ti-msgmgr.c
@@ -190,6 +190,53 @@ static inline bool ti_msgmgr_queue_is_error(const struct ti_msgmgr_desc *d,
 	return val ? true : false;
 }
 
+static int ti_msgmgr_queue_rx_data(struct mbox_chan *chan, struct ti_queue_inst *qinst,
+				   const struct ti_msgmgr_desc *desc)
+{
+	int num_words;
+	struct ti_msgmgr_message message;
+	void __iomem *data_reg;
+	u32 *word_data;
+
+	/*
+	 * I have no idea about the protocol being used to communicate with the
+	 * remote producer - 0 could be valid data, so I wont make a judgement
+	 * of how many bytes I should be reading. Let the client figure this
+	 * out.. I just read the full message and pass it on..
+	 */
+	message.len = desc->max_message_size;
+	message.buf = (u8 *)qinst->rx_buff;
+
+	/*
+	 * NOTE about register access involved here:
+	 * the hardware block is implemented with 32bit access operations and no
+	 * support for data splitting.  We don't want the hardware to misbehave
+	 * with sub 32bit access - For example: if the last register read is
+	 * split into byte wise access, it can result in the queue getting
+	 * stuck or indeterminate behavior. An out of order read operation may
+	 * result in weird data results as well.
+	 * Hence, we do not use memcpy_fromio or __ioread32_copy here, instead
+	 * we depend on readl for the purpose.
+	 *
+	 * Also note that the final register read automatically marks the
+	 * queue message as read.
+	 */
+	for (data_reg = qinst->queue_buff_start, word_data = qinst->rx_buff,
+	     num_words = (desc->max_message_size / sizeof(u32));
+	     num_words; num_words--, data_reg += sizeof(u32), word_data++)
+		*word_data = readl(data_reg);
+
+	/*
+	 * Last register read automatically clears the IRQ if only 1 message
+	 * is pending - so send the data up the stack..
+	 * NOTE: Client is expected to be as optimal as possible, since
+	 * we invoke the handler in IRQ context.
+	 */
+	mbox_chan_received_data(chan, (void *)&message);
+
+	return 0;
+}
+
 /**
  * ti_msgmgr_queue_rx_interrupt() - Interrupt handler for receive Queue
  * @irq:	Interrupt number
@@ -206,10 +253,7 @@ static irqreturn_t ti_msgmgr_queue_rx_interrupt(int irq, void *p)
 	struct ti_msgmgr_inst *inst = dev_get_drvdata(dev);
 	struct ti_queue_inst *qinst = chan->con_priv;
 	const struct ti_msgmgr_desc *desc;
-	int msg_count, num_words;
-	struct ti_msgmgr_message message;
-	void __iomem *data_reg;
-	u32 *word_data;
+	int msg_count;
 
 	if (WARN_ON(!inst)) {
 		dev_err(dev, "no platform drv data??\n");
@@ -237,41 +281,7 @@ static irqreturn_t ti_msgmgr_queue_rx_interrupt(int irq, void *p)
 		return IRQ_NONE;
 	}
 
-	/*
-	 * I have no idea about the protocol being used to communicate with the
-	 * remote producer - 0 could be valid data, so I won't make a judgement
-	 * of how many bytes I should be reading. Let the client figure this
-	 * out.. I just read the full message and pass it on..
-	 */
-	message.len = desc->max_message_size;
-	message.buf = (u8 *)qinst->rx_buff;
-
-	/*
-	 * NOTE about register access involved here:
-	 * the hardware block is implemented with 32bit access operations and no
-	 * support for data splitting.  We don't want the hardware to misbehave
-	 * with sub 32bit access - For example: if the last register read is
-	 * split into byte wise access, it can result in the queue getting
-	 * stuck or indeterminate behavior. An out of order read operation may
-	 * result in weird data results as well.
-	 * Hence, we do not use memcpy_fromio or __ioread32_copy here, instead
-	 * we depend on readl for the purpose.
-	 *
-	 * Also note that the final register read automatically marks the
-	 * queue message as read.
-	 */
-	for (data_reg = qinst->queue_buff_start, word_data = qinst->rx_buff,
-	     num_words = (desc->max_message_size / sizeof(u32));
-	     num_words; num_words--, data_reg += sizeof(u32), word_data++)
-		*word_data = readl(data_reg);
-
-	/*
-	 * Last register read automatically clears the IRQ if only 1 message
-	 * is pending - so send the data up the stack..
-	 * NOTE: Client is expected to be as optimal as possible, since
-	 * we invoke the handler in IRQ context.
-	 */
-	mbox_chan_received_data(chan, (void *)&message);
+	ti_msgmgr_queue_rx_data(chan, qinst, desc);
 
 	return IRQ_HANDLED;
 }
-- 
2.35.0