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Date:   Tue,  6 Dec 2016 13:57:15 +1100
From:   Andrew Jeffery <andrew@...id.au>
To:     Corey Minyard <minyard@....org>
Cc:     Andrew Jeffery <andrew@...id.au>,
        C├ędric Le Goater <clg@...d.org>,
        Joel Stanley <joel@....id.au>,
        openipmi-developer@...ts.sourceforge.net,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: [PATCH] ipmi: bt-bmc: Use a regmap for register access

The registers for the bt-bmc device live under the Aspeed LPC
controller. Devicetree bindings have recently been introduced for the
LPC controller where the "host" portion of the LPC register space is
described as a syscon device. Future devicetrees describing the bt-bmc
device should nest its node under the appropriate "simple-mfd", "syscon"
compatible node.

This change allows the bt-bmc driver to function with both syscon and
non-syscon- based devicetree descriptions by always using a regmap for
register access, either retrieved from the parent syscon device or
instantiated if none exists.

The patch has been tested on an OpenPOWER Palmetto machine, successfully
booting, rebooting and powering down the host.

Signed-off-by: Andrew Jeffery <andrew@...id.au>
---
 drivers/char/ipmi/Kconfig  |  1 +
 drivers/char/ipmi/bt-bmc.c | 82 ++++++++++++++++++++++++++++++++++------------
 2 files changed, 62 insertions(+), 21 deletions(-)

diff --git a/drivers/char/ipmi/Kconfig b/drivers/char/ipmi/Kconfig
index 7f816655cbbf..b5d48d9af124 100644
--- a/drivers/char/ipmi/Kconfig
+++ b/drivers/char/ipmi/Kconfig
@@ -79,6 +79,7 @@ endif # IPMI_HANDLER
 
 config ASPEED_BT_IPMI_BMC
 	depends on ARCH_ASPEED
+        depends on REGMAP && REGMAP_MMIO && MFD_SYSCON
 	tristate "BT IPMI bmc driver"
 	help
 	  Provides a driver for the BT (Block Transfer) IPMI interface
diff --git a/drivers/char/ipmi/bt-bmc.c b/drivers/char/ipmi/bt-bmc.c
index fc9e8891eae3..ca1e20f6c6c5 100644
--- a/drivers/char/ipmi/bt-bmc.c
+++ b/drivers/char/ipmi/bt-bmc.c
@@ -12,10 +12,13 @@
 #include <linux/errno.h>
 #include <linux/interrupt.h>
 #include <linux/io.h>
+#include <linux/mfd/syscon.h>
 #include <linux/miscdevice.h>
 #include <linux/module.h>
+#include <linux/of.h>
 #include <linux/platform_device.h>
 #include <linux/poll.h>
+#include <linux/regmap.h>
 #include <linux/sched.h>
 #include <linux/timer.h>
 
@@ -60,7 +63,8 @@
 struct bt_bmc {
 	struct device		dev;
 	struct miscdevice	miscdev;
-	void __iomem		*base;
+	struct regmap		*map;
+	int			offset;
 	int			irq;
 	wait_queue_head_t	queue;
 	struct timer_list	poll_timer;
@@ -69,14 +73,31 @@ struct bt_bmc {
 
 static atomic_t open_count = ATOMIC_INIT(0);
 
+static struct regmap_config bt_regmap_cfg = {
+	.reg_bits = 32,
+	.val_bits = 32,
+	.reg_stride = 4,
+};
+
 static u8 bt_inb(struct bt_bmc *bt_bmc, int reg)
 {
-	return ioread8(bt_bmc->base + reg);
+	uint32_t val = 0;
+	int rc;
+
+	rc = regmap_read(bt_bmc->map, bt_bmc->offset + reg, &val);
+	WARN(rc != 0, "%s:%d: regmap_read() failed: %d\n",
+			__FILE__, __LINE__, rc);
+
+	return rc == 0 ? (u8) val : 0;
 }
 
 static void bt_outb(struct bt_bmc *bt_bmc, u8 data, int reg)
 {
-	iowrite8(data, bt_bmc->base + reg);
+	int rc;
+
+	rc = regmap_write(bt_bmc->map, bt_bmc->offset + reg, data);
+	WARN(rc != 0, "%s:%d: regmap_write() failed: %d\n",
+			__FILE__, __LINE__, rc);
 }
 
 static void clr_rd_ptr(struct bt_bmc *bt_bmc)
@@ -367,14 +388,18 @@ static irqreturn_t bt_bmc_irq(int irq, void *arg)
 {
 	struct bt_bmc *bt_bmc = arg;
 	u32 reg;
+	int rc;
+
+	rc = regmap_read(bt_bmc->map, bt_bmc->offset + BT_CR2, &reg);
+	if (rc)
+		return IRQ_NONE;
 
-	reg = ioread32(bt_bmc->base + BT_CR2);
 	reg &= BT_CR2_IRQ_H2B | BT_CR2_IRQ_HBUSY;
 	if (!reg)
 		return IRQ_NONE;
 
 	/* ack pending IRQs */
-	iowrite32(reg, bt_bmc->base + BT_CR2);
+	regmap_write(bt_bmc->map, bt_bmc->offset + BT_CR2, reg);
 
 	wake_up(&bt_bmc->queue);
 	return IRQ_HANDLED;
@@ -384,7 +409,6 @@ static int bt_bmc_config_irq(struct bt_bmc *bt_bmc,
 			     struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
-	u32 reg;
 	int rc;
 
 	bt_bmc->irq = platform_get_irq(pdev, 0);
@@ -405,18 +429,17 @@ static int bt_bmc_config_irq(struct bt_bmc *bt_bmc,
 	 * will be cleared (along with B2H) when we can write the next
 	 * message to the BT buffer
 	 */
-	reg = ioread32(bt_bmc->base + BT_CR1);
-	reg |= BT_CR1_IRQ_H2B | BT_CR1_IRQ_HBUSY;
-	iowrite32(reg, bt_bmc->base + BT_CR1);
+	rc = regmap_update_bits(bt_bmc->map, bt_bmc->offset + BT_CR1,
+				(BT_CR1_IRQ_H2B | BT_CR1_IRQ_HBUSY),
+				(BT_CR1_IRQ_H2B | BT_CR1_IRQ_HBUSY));
 
-	return 0;
+	return rc;
 }
 
 static int bt_bmc_probe(struct platform_device *pdev)
 {
 	struct bt_bmc *bt_bmc;
 	struct device *dev;
-	struct resource *res;
 	int rc;
 
 	if (!pdev || !pdev->dev.of_node)
@@ -431,10 +454,27 @@ static int bt_bmc_probe(struct platform_device *pdev)
 
 	dev_set_drvdata(&pdev->dev, bt_bmc);
 
-	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
-	bt_bmc->base = devm_ioremap_resource(&pdev->dev, res);
-	if (IS_ERR(bt_bmc->base))
-		return PTR_ERR(bt_bmc->base);
+	bt_bmc->map = syscon_node_to_regmap(pdev->dev.parent->of_node);
+	if (IS_ERR(bt_bmc->map)) {
+		struct resource *res;
+		void __iomem *base;
+
+		/*
+		 * Assume it's not the MFD-based devicetree description, in
+		 * which case generate a regmap ourselves
+		 */
+		res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+		base = devm_ioremap_resource(&pdev->dev, res);
+		if (IS_ERR(base))
+			return PTR_ERR(base);
+
+		bt_bmc->map = devm_regmap_init_mmio(dev, base, &bt_regmap_cfg);
+		bt_bmc->offset = 0;
+	} else {
+		rc = of_property_read_u32(dev->of_node, "reg", &bt_bmc->offset);
+		if (rc)
+			return rc;
+	}
 
 	mutex_init(&bt_bmc->mutex);
 	init_waitqueue_head(&bt_bmc->queue);
@@ -461,12 +501,12 @@ static int bt_bmc_probe(struct platform_device *pdev)
 		add_timer(&bt_bmc->poll_timer);
 	}
 
-	iowrite32((BT_IO_BASE << BT_CR0_IO_BASE) |
-		  (BT_IRQ << BT_CR0_IRQ) |
-		  BT_CR0_EN_CLR_SLV_RDP |
-		  BT_CR0_EN_CLR_SLV_WRP |
-		  BT_CR0_ENABLE_IBT,
-		  bt_bmc->base + BT_CR0);
+	regmap_write(bt_bmc->map, bt_bmc->offset + BT_CR0,
+		     (BT_IO_BASE << BT_CR0_IO_BASE) |
+		     (BT_IRQ << BT_CR0_IRQ) |
+		     BT_CR0_EN_CLR_SLV_RDP |
+		     BT_CR0_EN_CLR_SLV_WRP |
+		     BT_CR0_ENABLE_IBT);
 
 	clr_b_busy(bt_bmc);
 
-- 
2.9.3

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