mailbox: mpfs: support new, syscon based, devicetree configuration

The two previous bindings for this hardware were incorrect, as the
control/status and interrupt register regions should have been described
as syscons and dealt with via regmap in the driver. Add support for
accessing these registers using that method now, so that the hwmon
driver can be supported without using auxdev or hacks with io_remap().

Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Signed-off-by: Jassi Brar <jassisinghbrar@gmail.com>

drivers/mailbox/Kconfig

@@ -168,6 +168,7 @@ config MAILBOX_TEST
 config POLARFIRE_SOC_MAILBOX
 	tristate "PolarFire SoC (MPFS) Mailbox"
 	depends on HAS_IOMEM
+	depends on MFD_SYSCON
 	depends on ARCH_MICROCHIP_POLARFIRE || COMPILE_TEST
 	help
 	  This driver adds support for the PolarFire SoC (MPFS) mailbox controller.

drivers/mailbox/mailbox-mpfs.c

@@ -13,12 +13,15 @@
 #include <linux/init.h>
 #include <linux/module.h>
 #include <linux/kernel.h>
+#include <linux/regmap.h>
 #include <linux/interrupt.h>
+#include <linux/mfd/syscon.h>
 #include <linux/mod_devicetable.h>
 #include <linux/platform_device.h>
 #include <linux/mailbox_controller.h>
 #include <soc/microchip/mpfs.h>
 
+#define MESSAGE_INT_OFFSET		0x18cu
 #define SERVICES_CR_OFFSET		0x50u
 #define SERVICES_SR_OFFSET		0x54u
 #define MAILBOX_REG_OFFSET		0x800u
@@ -68,6 +71,7 @@ struct mpfs_mbox {
 	void __iomem *int_reg;
 	struct mbox_chan chans[1];
 	struct mpfs_mss_response *response;
+	struct regmap *sysreg_scb, *control_scb;
 	u16 resp_offset;
 };
 
@@ -75,7 +79,10 @@ static bool mpfs_mbox_busy(struct mpfs_mbox *mbox)
 {
 	u32 status;
 
-	status = readl_relaxed(mbox->ctrl_base + SERVICES_SR_OFFSET);
+	if (mbox->control_scb)
+		regmap_read(mbox->control_scb, SERVICES_SR_OFFSET, &status);
+	else
+		status = readl_relaxed(mbox->ctrl_base + SERVICES_SR_OFFSET);
 
 	return status & SCB_STATUS_BUSY_MASK;
 }
@@ -95,7 +102,11 @@ static bool mpfs_mbox_last_tx_done(struct mbox_chan *chan)
 	 * Failed services are intended to generated interrupts, but in reality
 	 * this does not happen, so the status must be checked here.
 	 */
-	val = readl_relaxed(mbox->ctrl_base + SERVICES_SR_OFFSET);
+	if (mbox->control_scb)
+		regmap_read(mbox->control_scb, SERVICES_SR_OFFSET, &val);
+	else
+		val = readl_relaxed(mbox->ctrl_base + SERVICES_SR_OFFSET);
+
 	response->resp_status = (val & SCB_STATUS_MASK) >> SCB_STATUS_POS;
 
 	return true;
@@ -143,7 +154,12 @@ static int mpfs_mbox_send_data(struct mbox_chan *chan, void *data)
 
 	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->ctrl_base + SERVICES_CR_OFFSET);
+
+	if (mbox->control_scb)
+		regmap_write(mbox->control_scb, SERVICES_CR_OFFSET, tx_trigger);
+	else
+		writel_relaxed(tx_trigger, mbox->ctrl_base + SERVICES_CR_OFFSET);
+
 
 	return 0;
 }
@@ -185,7 +201,10 @@ static irqreturn_t mpfs_mbox_inbox_isr(int irq, void *data)
 	struct mbox_chan *chan = data;
 	struct mpfs_mbox *mbox = (struct mpfs_mbox *)chan->con_priv;
 
-	writel_relaxed(0, mbox->int_reg);
+	if (mbox->control_scb)
+		regmap_write(mbox->sysreg_scb, MESSAGE_INT_OFFSET, 0);
+	else
+		writel_relaxed(0, mbox->int_reg);
 
 	mpfs_mbox_rx_data(chan);
 
@@ -221,28 +240,62 @@ static const struct mbox_chan_ops mpfs_mbox_ops = {
 	.last_tx_done = mpfs_mbox_last_tx_done,
 };
 
+static inline int mpfs_mbox_syscon_probe(struct mpfs_mbox *mbox, struct platform_device *pdev)
+{
+	mbox->control_scb = syscon_regmap_lookup_by_compatible("microchip,mpfs-control-scb");
+	if (IS_ERR(mbox->control_scb))
+		return PTR_ERR(mbox->control_scb);
+
+	mbox->sysreg_scb = syscon_regmap_lookup_by_compatible("microchip,mpfs-sysreg-scb");
+	if (IS_ERR(mbox->sysreg_scb))
+		return PTR_ERR(mbox->sysreg_scb);
+
+	mbox->mbox_base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(mbox->ctrl_base))
+		return PTR_ERR(mbox->mbox_base);
+
+	return 0;
+}
+
+static inline int mpfs_mbox_old_format_probe(struct mpfs_mbox *mbox, struct platform_device *pdev)
+{
+	dev_warn(&pdev->dev, "falling back to old devicetree format");
+
+	mbox->ctrl_base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(mbox->ctrl_base))
+		return PTR_ERR(mbox->ctrl_base);
+
+	mbox->int_reg = devm_platform_ioremap_resource(pdev, 1);
+	if (IS_ERR(mbox->int_reg))
+		return PTR_ERR(mbox->int_reg);
+
+	mbox->mbox_base = devm_platform_ioremap_resource(pdev, 2);
+	if (IS_ERR(mbox->mbox_base)) // account for the old dt-binding w/ 2 regs
+		mbox->mbox_base = mbox->ctrl_base + MAILBOX_REG_OFFSET;
+
+	return 0;
+}
+
 static int mpfs_mbox_probe(struct platform_device *pdev)
 {
 	struct mpfs_mbox *mbox;
-	struct resource *regs;
 	int ret;
 
 	mbox = devm_kzalloc(&pdev->dev, sizeof(*mbox), GFP_KERNEL);
 	if (!mbox)
 		return -ENOMEM;
 
-	mbox->ctrl_base = devm_platform_get_and_ioremap_resource(pdev, 0, &regs);
+	ret = mpfs_mbox_syscon_probe(mbox, pdev);
-	if (IS_ERR(mbox->ctrl_base))
+	if (ret) {
-		return PTR_ERR(mbox->ctrl_base);
+		/*
-
+		 * set this to null, so it can be used as the decision for to
-	mbox->int_reg = devm_platform_get_and_ioremap_resource(pdev, 1, &regs);
+		 * regmap or not to regmap
-	if (IS_ERR(mbox->int_reg))
+		 */
-		return PTR_ERR(mbox->int_reg);
+		mbox->control_scb = NULL;
-
+		ret = mpfs_mbox_old_format_probe(mbox, pdev);
-	mbox->mbox_base = devm_platform_get_and_ioremap_resource(pdev, 2, &regs);
+		if (ret)
-	if (IS_ERR(mbox->mbox_base)) // account for the old dt-binding w/ 2 regs
+			return ret;
-		mbox->mbox_base = mbox->ctrl_base + MAILBOX_REG_OFFSET;
+	}
-
 	mbox->irq = platform_get_irq(pdev, 0);
 	if (mbox->irq < 0)
 		return mbox->irq;