mailbox: mpfs: fix handling of the reg property

The "data" region of the PolarFire SoC's system controller mailbox is
not one continuous register space - the system controller's QSPI sits
between the control and data registers. Split the "data" reg into two
parts: "data" & "control". Optionally get the "data" register address
from the 3rd reg property in the devicetree & fall back to using the
old base + MAILBOX_REG_OFFSET that the current code uses.

Fixes: 83d7b156 ("mbox: add polarfire soc system controller mailbox")
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>

drivers/mailbox/mailbox-mpfs.c

@@ -62,6 +62,7 @@ struct mpfs_mbox {
 	struct mbox_controller controller;
 	struct device *dev;
 	int irq;
+	void __iomem *ctrl_base;
 	void __iomem *mbox_base;
 	void __iomem *int_reg;
 	struct mbox_chan chans[1];
@@ -73,7 +74,7 @@ static bool mpfs_mbox_busy(struct mpfs_mbox *mbox)
 {
 	u32 status;
 
-	status = readl_relaxed(mbox->mbox_base + SERVICES_SR_OFFSET);
+	status = readl_relaxed(mbox->ctrl_base + SERVICES_SR_OFFSET);
 
 	return status & SCB_STATUS_BUSY_MASK;
 }
@@ -99,14 +100,13 @@ static int mpfs_mbox_send_data(struct mbox_chan *chan, void *data)
 
 		for (index = 0; index < (msg->cmd_data_size / 4); index++)
 			writel_relaxed(word_buf[index],
-				       mbox->mbox_base + MAILBOX_REG_OFFSET + index * 0x4);
+				       mbox->mbox_base + index * 0x4);
 		if (extra_bits) {
 			u8 i;
 			u8 byte_off = ALIGN_DOWN(msg->cmd_data_size, 4);
 			u8 *byte_buf = msg->cmd_data + byte_off;
 
-			val = readl_relaxed(mbox->mbox_base +
-					    MAILBOX_REG_OFFSET + index * 0x4);
+			val = readl_relaxed(mbox->mbox_base + index * 0x4);
 
 			for (i = 0u; i < extra_bits; i++) {
 				val &= ~(0xffu << (i * 8u));
@@ -114,14 +114,14 @@ static int mpfs_mbox_send_data(struct mbox_chan *chan, void *data)
 			}
 
 			writel_relaxed(val,
-				       mbox->mbox_base + MAILBOX_REG_OFFSET + index * 0x4);
+				       mbox->mbox_base + index * 0x4);
 		}
 	}
 
 	opt_sel = ((msg->mbox_offset << 7u) | (msg->cmd_opcode & 0x7fu));
 	tx_trigger = (opt_sel << SCB_CTRL_POS) & SCB_CTRL_MASK;
 	tx_trigger |= SCB_CTRL_REQ_MASK | SCB_STATUS_NOTIFY_MASK;
-	writel_relaxed(tx_trigger, mbox->mbox_base + SERVICES_CR_OFFSET);
+	writel_relaxed(tx_trigger, mbox->ctrl_base + SERVICES_CR_OFFSET);
 
 	return 0;
 }
@@ -141,7 +141,7 @@ static void mpfs_mbox_rx_data(struct mbox_chan *chan)
 	if (!mpfs_mbox_busy(mbox)) {
 		for (i = 0; i < num_words; i++) {
 			response->resp_msg[i] =
-				readl_relaxed(mbox->mbox_base + MAILBOX_REG_OFFSET
+				readl_relaxed(mbox->mbox_base
 					      + mbox->resp_offset + i * 0x4);
 		}
 	}
@@ -200,14 +200,18 @@ static int mpfs_mbox_probe(struct platform_device *pdev)
 	if (!mbox)
 		return -ENOMEM;
 
-	mbox->mbox_base = devm_platform_get_and_ioremap_resource(pdev, 0, &regs);
-	if (IS_ERR(mbox->mbox_base))
-		return PTR_ERR(mbox->mbox_base);
+	mbox->ctrl_base = devm_platform_get_and_ioremap_resource(pdev, 0, &regs);
+	if (IS_ERR(mbox->ctrl_base))
+		return PTR_ERR(mbox->ctrl_base);
 
 	mbox->int_reg = devm_platform_get_and_ioremap_resource(pdev, 1, &regs);
 	if (IS_ERR(mbox->int_reg))
 		return PTR_ERR(mbox->int_reg);
 
+	mbox->mbox_base = devm_platform_get_and_ioremap_resource(pdev, 2, &regs);
+	if (IS_ERR(mbox->mbox_base)) // account for the old dt-binding w/ 2 regs
+		mbox->mbox_base = mbox->ctrl_base + MAILBOX_REG_OFFSET;
+
 	mbox->irq = platform_get_irq(pdev, 0);
 	if (mbox->irq < 0)
 		return mbox->irq;