[Openipmi-developer] [PATCH] ipmi: bt-bmc: Use registers directly

[Joel S. <jo...@jm...>]

This driver was originally written to use the regmap abstraction with no
clear benefit. As the registers are always mmio and there is no sharing
of the region with other devices, we can safely read and write without
the locking that regmap provides.

This reduces the code size of the driver by about 25%.

Signed-off-by: Joel Stanley <jo...@jm...>
---
 drivers/char/ipmi/bt-bmc.c | 68 +++++++++-----------------------------
 1 file changed, 16 insertions(+), 52 deletions(-)

diff --git a/drivers/char/ipmi/bt-bmc.c b/drivers/char/ipmi/bt-bmc.c
index 6e3d247b55d1..fb771ce6f7bf 100644
--- a/drivers/char/ipmi/bt-bmc.c
+++ b/drivers/char/ipmi/bt-bmc.c
@@ -8,13 +8,11 @@
 #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>
 
@@ -59,8 +57,7 @@
 struct bt_bmc {
 	struct device		dev;
 	struct miscdevice	miscdev;
-	struct regmap		*map;
-	int			offset;
+	void __iomem		*base;
 	int			irq;
 	wait_queue_head_t	queue;
 	struct timer_list	poll_timer;
@@ -69,29 +66,14 @@ struct bt_bmc {
 
 static atomic_t open_count = ATOMIC_INIT(0);
 
-static const 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)
 {
-	uint32_t val = 0;
-	int rc;
-
-	rc = regmap_read(bt_bmc->map, bt_bmc->offset + reg, &val);
-	WARN(rc != 0, "regmap_read() failed: %d\n", rc);
-
-	return rc == 0 ? (u8) val : 0;
+	return readb(bt_bmc->base + reg);
 }
 
 static void bt_outb(struct bt_bmc *bt_bmc, u8 data, int reg)
 {
-	int rc;
-
-	rc = regmap_write(bt_bmc->map, bt_bmc->offset + reg, data);
-	WARN(rc != 0, "regmap_write() failed: %d\n", rc);
+	writeb(data, bt_bmc->base + reg);
 }
 
 static void clr_rd_ptr(struct bt_bmc *bt_bmc)
@@ -376,18 +358,15 @@ 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 = readl(bt_bmc->base + BT_CR2);
 
 	reg &= BT_CR2_IRQ_H2B | BT_CR2_IRQ_HBUSY;
 	if (!reg)
 		return IRQ_NONE;
 
 	/* ack pending IRQs */
-	regmap_write(bt_bmc->map, bt_bmc->offset + BT_CR2, reg);
+	writel(reg, bt_bmc->base + BT_CR2);
 
 	wake_up(&bt_bmc->queue);
 	return IRQ_HANDLED;
@@ -398,6 +377,7 @@ static int bt_bmc_config_irq(struct bt_bmc *bt_bmc,
 {
 	struct device *dev = &pdev->dev;
 	int rc;
+	u32 reg;
 
 	bt_bmc->irq = platform_get_irq_optional(pdev, 0);
 	if (bt_bmc->irq < 0)
@@ -417,11 +397,11 @@ 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
 	 */
-	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));
+	reg = readl(bt_bmc->base + BT_CR1);
+	reg |= BT_CR1_IRQ_H2B | BT_CR1_IRQ_HBUSY;
+	writel(reg, bt_bmc->base + BT_CR1);
 
-	return rc;
+	return 0;
 }
 
 static int bt_bmc_probe(struct platform_device *pdev)
@@ -439,25 +419,9 @@ static int bt_bmc_probe(struct platform_device *pdev)
 
 	dev_set_drvdata(&pdev->dev, bt_bmc);
 
-	bt_bmc->map = syscon_node_to_regmap(pdev->dev.parent->of_node);
-	if (IS_ERR(bt_bmc->map)) {
-		void __iomem *base;
-
-		/*
-		 * Assume it's not the MFD-based devicetree description, in
-		 * which case generate a regmap ourselves
-		 */
-		base = devm_platform_ioremap_resource(pdev, 0);
-		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;
-	}
+	bt_bmc->base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(bt_bmc->base))
+		return PTR_ERR(bt_bmc->base);
 
 	mutex_init(&bt_bmc->mutex);
 	init_waitqueue_head(&bt_bmc->queue);
@@ -483,12 +447,12 @@ static int bt_bmc_probe(struct platform_device *pdev)
 		add_timer(&bt_bmc->poll_timer);
 	}
 
-	regmap_write(bt_bmc->map, bt_bmc->offset + BT_CR0,
-		     (BT_IO_BASE << BT_CR0_IO_BASE) |
+	writel((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_CR0_ENABLE_IBT,
+		bt_bmc->base + BT_CR0);
 
 	clr_b_busy(bt_bmc);
 
-- 
2.33.0