[PATCH linux dev-5.10 v2 5/7] misc: Remove obsolete mctp-lpc chardev

[Andrew Jeffery <andrew@aj.id.au>]

The mctp-lpc chardev is replaced (temporarily) by the raw KCS chardev.
The raw chardev is required for IBM's purposes until Jeremy's
socket-based MCTP patches are merged[1][2].

[1] https://github.com/openbmc/docs/blob/master/designs/mctp/mctp-kernel.md
[2] https://lore.kernel.org/openbmc/f4f5fa66542401e8d5e78c1fb30153195d384b62.camel@codeconstruct.com.au/

Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
---
 arch/arm/configs/aspeed_g5_defconfig |   1 -
 drivers/misc/Kconfig                 |   7 -
 drivers/misc/Makefile                |   1 -
 drivers/misc/mctp-lpc.c              | 443 ---------------------------
 4 files changed, 452 deletions(-)
 delete mode 100644 drivers/misc/mctp-lpc.c

diff --git a/arch/arm/configs/aspeed_g5_defconfig b/arch/arm/configs/aspeed_g5_defconfig
index 045d383ce5ce..550884fee892 100644
--- a/arch/arm/configs/aspeed_g5_defconfig
+++ b/arch/arm/configs/aspeed_g5_defconfig
@@ -111,7 +111,6 @@ CONFIG_MTD_UBI_FASTMAP=y
 CONFIG_MTD_UBI_BLOCK=y
 CONFIG_BLK_DEV_LOOP=y
 CONFIG_BLK_DEV_NBD=y
-CONFIG_MCTP_LPC=y
 CONFIG_EEPROM_AT24=y
 CONFIG_EEPROM_AT25=y
 CONFIG_MD=y
diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig
index c1322e9bee8a..54cfb599cd3e 100644
--- a/drivers/misc/Kconfig
+++ b/drivers/misc/Kconfig
@@ -444,13 +444,6 @@ config XILINX_SDFEC
 
 	  If unsure, say N.
 
-config MCTP_LPC
-	tristate "MCTP LPC binding implementation for ASPEED BMCs"
-	depends on REGMAP
-	help
-	  Implements the MCTP LPC binding via KCS LPC IO cycles for control and
-          LPC FWH cycles for data
-
 config MISC_RTSX
 	tristate
 	default MISC_RTSX_PCI || MISC_RTSX_USB
diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile
index bcc79a1d7a72..39e5ba5d0985 100644
--- a/drivers/misc/Makefile
+++ b/drivers/misc/Makefile
@@ -60,4 +60,3 @@ obj-$(CONFIG_HISI_HIKEY_USB)	+= hisi_hikey_usb.o
 obj-$(CONFIG_NPCM7XX_LPC_BPC)	+= npcm7xx-lpc-bpc.o
 obj-$(CONFIG_NPCM7XX_PCI_MBOX)	+= npcm7xx-pci-mbox.o
 obj-$(CONFIG_NPCM7XX_JTAG_MASTER)	+= npcm7xx-jtag-master.o
-obj-$(CONFIG_MCTP_LPC)		+= mctp-lpc.o
diff --git a/drivers/misc/mctp-lpc.c b/drivers/misc/mctp-lpc.c
deleted file mode 100644
index 0228f6bbf1a7..000000000000
--- a/drivers/misc/mctp-lpc.c
+++ /dev/null
@@ -1,443 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0+
-/*
- * Copyright (c) 2019, IBM Corp.
- */
-
-#include <linux/errno.h>
-#include <linux/fs.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/signal.h>
-#include <linux/uaccess.h>
-#include <linux/wait.h>
-
-#define LPC_HICRB            0x100
-#define     LPC_HICRB_IBFIF4         BIT(1)
-#define     LPC_HICRB_LPC4E          BIT(0)
-#define LPC_HICRC            0x104
-#define     LPC_KCS4_IRQSEL_MASK     GENMASK(7, 4)
-#define     LPC_KCS4_IRQSEL_SHIFT    4
-#define     LPC_KCS4_IRQTYPE_MASK    GENMASK(3, 2)
-#define     LPC_KCS4_IRQTYPE_SHIFT   2
-#define     LPC_KCS4_IRQTYPE_LOW     0b00
-#define     LPC_KCS4_IRQTYPE_HIGH    0b01
-#define     LPC_KCS4_IRQTYPE_RSVD    0b10
-#define     LPC_KCS4_IRQTYPE_RISING  0b11
-#define     LPC_KCS4_OBF4_AUTO_CLR   BIT(1)
-#define     LPC_KCS4_IRQ_HOST	     BIT(0)
-#define LPC_LADR4            0x110
-#define LPC_IDR4             0x114
-#define LPC_ODR4             0x118
-#define LPC_STR4             0x11C
-#define     STR4_IBF	     (1 << 1)
-#define     STR4_OBF	     (1 << 0)
-
-#define HOST_ODR             0xca2
-#define HOST_STR             0xca3
-#define HOST_SERIRQ_ID       11
-#define HOST_SERIRQ_TYPE     LPC_KCS4_IRQTYPE_LOW
-
-#define RX_BUF_SIZE 1024
-
-struct mctp_lpc {
-	struct miscdevice miscdev;
-	struct regmap *map;
-
-	wait_queue_head_t rx;
-	bool pending;
-	u8 idr;
-};
-
-static irqreturn_t mctp_lpc_irq(int irq, void *data)
-{
-	struct mctp_lpc *priv = data;
-	unsigned long flags;
-	unsigned int hicrb;
-	struct device *dev;
-	unsigned int str;
-	irqreturn_t ret;
-
-	dev = priv->miscdev.this_device;
-
-	spin_lock_irqsave(&priv->rx.lock, flags);
-
-	regmap_read(priv->map, LPC_STR4, &str);
-	regmap_read(priv->map, LPC_HICRB, &hicrb);
-
-	if ((str & STR4_IBF) && (hicrb & LPC_HICRB_IBFIF4)) {
-		unsigned int val;
-
-		if (priv->pending)
-			dev_err(dev, "Storm brewing!");
-
-		/* Mask the IRQ / Enter polling mode */
-		dev_dbg(dev, "Received IRQ %d, disabling to provide back-pressure\n",
-			irq);
-		regmap_update_bits(priv->map, LPC_HICRB, LPC_HICRB_IBFIF4, 0);
-
-		/*
-		 * Extract the IDR4 value to ack the IRQ. Reading IDR clears
-		 * IBF and allows the host to write another value, however as
-		 * we have disabled IRQs the back-pressure is still applied
-		 * until userspace starts servicing the interface.
-		 */
-		regmap_read(priv->map, LPC_IDR4, &val);
-		priv->idr = val & 0xff;
-		priv->pending = true;
-
-		dev_dbg(dev, "Set pending, waking waiters\n");
-		wake_up_locked(&priv->rx);
-		ret = IRQ_HANDLED;
-	} else {
-		dev_dbg(dev, "LPC IRQ triggered, but not for us (str=0x%x, hicrb=0x%x)\n",
-			str, hicrb);
-		ret = IRQ_NONE;
-	}
-
-	spin_unlock_irqrestore(&priv->rx.lock, flags);
-
-	return ret;
-}
-
-static inline struct mctp_lpc *to_mctp_lpc(struct file *filp)
-{
-	return container_of(filp->private_data, struct mctp_lpc, miscdev);
-}
-
-static ssize_t mctp_lpc_read(struct file *filp, char __user *buf,
-			     size_t count, loff_t *ppos)
-{
-	struct mctp_lpc *priv;
-	struct device *dev;
-	size_t remaining;
-	ssize_t rc;
-
-	priv = to_mctp_lpc(filp);
-	dev = priv->miscdev.this_device;
-
-	if (!count)
-		return 0;
-
-	if (count > 2 || *ppos > 1)
-		return -EINVAL;
-
-	remaining = count;
-
-	spin_lock_irq(&priv->rx.lock);
-	if (*ppos == 0) {
-		unsigned int val;
-		u8 str;
-
-		/* YOLO blocking, non-block not supported */
-		dev_dbg(dev, "Waiting for IBF\n");
-		regmap_read(priv->map, LPC_STR4, &val);
-		str = val & 0xff;
-		rc = wait_event_interruptible_locked(priv->rx, (priv->pending || str & STR4_IBF));
-		if (rc < 0)
-			goto out;
-
-		if (signal_pending(current)) {
-			dev_dbg(dev, "Interrupted waiting for IBF\n");
-			rc = -EINTR;
-			goto out;
-		}
-
-		/*
-		 * Re-enable IRQs prior to possible read of IDR (which clears
-		 * IBF) to ensure we receive interrupts for subsequent writes
-		 * to IDR. Writes to IDR by the host should not occur while IBF
-		 * is set.
-		 */
-		dev_dbg(dev, "Woken by IBF, enabling IRQ\n");
-		regmap_update_bits(priv->map, LPC_HICRB, LPC_HICRB_IBFIF4,
-				   LPC_HICRB_IBFIF4);
-
-		/* Read data out of IDR into internal storage if necessary */
-		if (!priv->pending) {
-			WARN(!(str & STR4_IBF), "Unknown reason for wakeup!");
-
-			/* Extract the IDR4 value to ack the IRQ */
-			regmap_read(priv->map, LPC_IDR4, &val);
-			priv->idr = val & 0xff;
-		}
-
-		/* Copy data from internal storage to userspace */
-		if (copy_to_user(buf, &priv->idr, sizeof(priv->idr))) {
-			rc = -EFAULT;
-			goto out;
-		}
-
-		/* We're done consuming the internally stored value */
-		priv->pending = false;
-
-		remaining--;
-		buf++;
-	}
-
-	if (remaining) {
-		/* Either:
-		 *
-		 * 1. (count == 1 && *ppos == 1)
-		 * 2. (count == 2 && *ppos == 0)
-		 */
-		unsigned int val;
-		u8 str;
-
-		regmap_read(priv->map, LPC_STR4, &val);
-		str = val & 0xff;
-		if (*ppos == 0 || priv->pending)
-			/*
-			 * If we got this far with `*ppos == 0` then we've read
-			 * data out of IDR, so set IBF when reporting back to
-			 * userspace so userspace knows the IDR value is valid.
-			 */
-			str |= STR4_IBF;
-
-		dev_dbg(dev, "Read status 0x%x\n", str);
-		if (copy_to_user(buf, &str, sizeof(str))) {
-			rc = -EFAULT;
-			goto out;
-		}
-
-		remaining--;
-	}
-
-	WARN_ON(remaining);
-
-	rc = count;
-
-out:
-	spin_unlock_irq(&priv->rx.lock);
-
-	return rc;
-}
-
-static ssize_t mctp_lpc_write(struct file *filp, const char __user *buf,
-			      size_t count, loff_t *ppos)
-{
-	uint8_t _data[2], *data = &_data[0];
-	struct mctp_lpc *priv;
-	struct device *dev;
-	size_t remaining;
-	unsigned int str;
-
-	priv = to_mctp_lpc(filp);
-	dev = priv->miscdev.this_device;
-
-	if (!count)
-		return count;
-
-	if (count > 2)
-		return -EINVAL;
-
-	if (*ppos >= 2)
-		return -EINVAL;
-
-	if (*ppos + count > 2)
-		return -EINVAL;
-
-	if (copy_from_user(data, buf, count))
-		return -EFAULT;
-
-	remaining = count;
-
-	if (*ppos == 0) {
-		/* Wait until OBF is clear - we don't get an IRQ */
-		dev_dbg(dev, "Waiting for OBF to clear\n");
-		for (;;) {
-			if (signal_pending(current))
-				return -EINTR;
-
-			regmap_read(priv->map, LPC_STR4, &str);
-			if (!(str & STR4_OBF))
-				break;
-
-			msleep(1);
-		}
-
-		dev_dbg(dev, "Writing 0x%x to ODR\n", *data);
-		regmap_write(priv->map, LPC_ODR4, *data);
-		remaining--;
-		data++;
-	}
-
-	if (remaining) {
-		if (!(*data & STR4_OBF))
-			dev_err(dev, "Clearing OBF with status write: 0x%x\n",
-				*data);
-		dev_dbg(dev, "Writing status 0x%x\n", *data);
-		regmap_write(priv->map, LPC_STR4, *data);
-		remaining--;
-	}
-
-	WARN_ON(remaining);
-
-	regmap_read(priv->map, LPC_STR4, &str);
-	dev_dbg(dev, "Triggering SerIRQ (current str=0x%x)\n", str);
-
-	/*
-	 * Trigger Host IRQ on ODR write. Do this after any STR write in case
-	 * we need to write ODR to indicate an STR update (which we do).
-	 */
-	if (*ppos == 0)
-		regmap_update_bits(priv->map, LPC_HICRC, LPC_KCS4_IRQ_HOST,
-				   LPC_KCS4_IRQ_HOST);
-
-	return count;
-}
-
-static __poll_t mctp_lpc_poll(struct file *filp, poll_table *wait)
-{
-	struct mctp_lpc *priv;
-	struct device *dev;
-	unsigned int val;
-	bool ibf;
-
-	priv = to_mctp_lpc(filp);
-	dev = priv->miscdev.this_device;
-
-	regmap_read(priv->map, LPC_STR4, &val);
-
-	spin_lock_irq(&priv->rx.lock);
-
-	ibf = priv->pending || val & STR4_IBF;
-
-	if (!ibf) {
-		dev_dbg(dev, "Polling on IBF\n");
-
-		spin_unlock_irq(&priv->rx.lock);
-
-		poll_wait(filp, &priv->rx, wait);
-		if (signal_pending(current)) {
-			dev_dbg(dev, "Polling IBF was interrupted\n");
-			goto out;
-		}
-
-		spin_lock_irq(&priv->rx.lock);
-
-		regmap_read(priv->map, LPC_STR4, &val);
-
-		ibf = priv->pending || val & STR4_IBF;
-	}
-
-	spin_unlock_irq(&priv->rx.lock);
-
-out:
-	dev_dbg(dev, "Polled IBF state: %s\n", ibf ? "set" : "clear");
-
-	return ibf ? EPOLLIN : 0;
-}
-
-static const struct file_operations mctp_lpc_fops = {
-	.owner          = THIS_MODULE,
-	.llseek		= no_seek_end_llseek,
-	.read           = mctp_lpc_read,
-	.write          = mctp_lpc_write,
-	.poll		= mctp_lpc_poll,
-};
-
-static int mctp_lpc_probe(struct platform_device *pdev)
-{
-	struct device *dev = &pdev->dev;
-	unsigned int mask, val;
-	struct mctp_lpc *priv;
-	int irq;
-	int rc;
-
-	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
-	if (!priv)
-		return -ENOMEM;
-
-	priv->map = syscon_node_to_regmap(dev->parent->of_node);
-	if (IS_ERR(priv->map)) {
-		dev_err(dev, "Couldn't get regmap\n");
-		return -ENODEV;
-	}
-
-	/*
-	 * Set the LPC address. Simultaneously, test our MMIO regmap works. All
-	 * subsequent accesses are assumed to work
-	 */
-	rc = regmap_write(priv->map, LPC_LADR4, ((HOST_STR) << 16) | HOST_ODR);
-	if (rc < 0)
-		return rc;
-
-	/* Set up the SerIRQ */
-	mask = LPC_KCS4_IRQSEL_MASK
-		| LPC_KCS4_IRQTYPE_MASK
-		| LPC_KCS4_OBF4_AUTO_CLR;
-	val = (HOST_SERIRQ_ID << LPC_KCS4_IRQSEL_SHIFT)
-		| (HOST_SERIRQ_TYPE << LPC_KCS4_IRQTYPE_SHIFT);
-	val &= ~LPC_KCS4_OBF4_AUTO_CLR; /* Unnecessary, just documentation */
-	regmap_update_bits(priv->map, LPC_HICRC, mask, val);
-
-	/* Trigger waiters from IRQ */
-	init_waitqueue_head(&priv->rx);
-
-	dev_set_drvdata(dev, priv);
-
-	/* Set up the miscdevice */
-	priv->miscdev.minor = MISC_DYNAMIC_MINOR;
-	priv->miscdev.name = "mctp0";
-	priv->miscdev.fops = &mctp_lpc_fops;
-
-	/* Configure the IRQ handler */
-	irq = platform_get_irq(pdev, 0);
-	if (irq < 0)
-		return irq;
-
-	rc = devm_request_irq(dev, irq, mctp_lpc_irq, IRQF_SHARED,
-			      dev_name(dev), priv);
-	if (rc < 0)
-		return rc;
-
-	/* Register the device */
-	rc = misc_register(&priv->miscdev);
-	if (rc) {
-		dev_err(dev, "Unable to register device\n");
-		return rc;
-	}
-
-	/* Enable the channel */
-	regmap_update_bits(priv->map, LPC_HICRB,
-			LPC_HICRB_IBFIF4 | LPC_HICRB_LPC4E,
-			LPC_HICRB_IBFIF4 | LPC_HICRB_LPC4E);
-
-	return 0;
-}
-
-static int mctp_lpc_remove(struct platform_device *pdev)
-{
-	struct mctp_lpc *ctx = dev_get_drvdata(&pdev->dev);
-
-	misc_deregister(&ctx->miscdev);
-
-	return 0;
-}
-
-static const struct of_device_id mctp_lpc_match[] = {
-	{ .compatible = "openbmc,mctp-lpc" },
-	{ }
-};
-MODULE_DEVICE_TABLE(of, mctp_lpc_match);
-
-static struct platform_driver mctp_lpc = {
-	.driver = {
-		.name           = "mctp-lpc",
-		.of_match_table = mctp_lpc_match,
-	},
-	.probe  = mctp_lpc_probe,
-	.remove = mctp_lpc_remove,
-};
-module_platform_driver(mctp_lpc);
-
-MODULE_LICENSE("GPL v2+");
-MODULE_AUTHOR("Andrew Jeffery <andrew@aj.id.au>");
-MODULE_DESCRIPTION("OpenBMC MCTP LPC binding on ASPEED KCS");
-- 
2.30.2