Subject: Re: [PATCH v3 06/16] ipmi: kcs_bmc: Split headers into device and client

From: Zev Weiss <[email-masked]>
Date: Fri, 21 May 2021 07:18:27 +0000

On Mon, May 10, 2021 at 12:42:03AM CDT, Andrew Jeffery wrote:
>Strengthen the distinction between code that abstracts the
>implementation of the KCS behaviours (device drivers) and code that
>exploits KCS behaviours (clients). Neither needs to know about the APIs
>required by the other, so provide separate headers.
>
>Signed-off-by: Andrew Jeffery <[email-masked]>
>---
> drivers/char/ipmi/kcs_bmc.c           | 23 ++++++++++------
> drivers/char/ipmi/kcs_bmc.h           | 27 +++++++++----------
> drivers/char/ipmi/kcs_bmc_aspeed.c    | 17 ++++++------
> drivers/char/ipmi/kcs_bmc_cdev_ipmi.c | 39 ++++++++++++++++++---------
> drivers/char/ipmi/kcs_bmc_client.h    | 30 +++++++++++++++++++++
> drivers/char/ipmi/kcs_bmc_device.h    | 19 +++++++++++++
> drivers/char/ipmi/kcs_bmc_npcm7xx.c   | 17 ++++++------
> 7 files changed, 120 insertions(+), 52 deletions(-)
> create mode 100644 drivers/char/ipmi/kcs_bmc_client.h
> create mode 100644 drivers/char/ipmi/kcs_bmc_device.h
>
>diff --git a/drivers/char/ipmi/kcs_bmc.c b/drivers/char/ipmi/kcs_bmc.c
>index 83da681bf49e..d3c11a46bca2 100644
>--- a/drivers/char/ipmi/kcs_bmc.c
>+++ b/drivers/char/ipmi/kcs_bmc.c
>@@ -1,46 +1,52 @@
> // SPDX-License-Identifier: GPL-2.0
> /*
>  * Copyright (c) 2015-2018, Intel Corporation.
>+ * Copyright (c) 2021, IBM Corp.
>  */
>
> #include <linux/module.h>
>
> #include "kcs_bmc.h"
>
>+/* Implement both the device and client interfaces here */
>+#include "kcs_bmc_device.h"
>+#include "kcs_bmc_client.h"
>+
>+/* Consumer data access */
>+
> u8 kcs_bmc_read_data(struct kcs_bmc *kcs_bmc)
> {
>-	return kcs_bmc->io_inputb(kcs_bmc, kcs_bmc->ioreg.idr);
>+	return kcs_bmc->ops->io_inputb(kcs_bmc, kcs_bmc->ioreg.idr);
> }
> EXPORT_SYMBOL(kcs_bmc_read_data);
>
> void kcs_bmc_write_data(struct kcs_bmc *kcs_bmc, u8 data)
> {
>-	kcs_bmc->io_outputb(kcs_bmc, kcs_bmc->ioreg.odr, data);
>+	kcs_bmc->ops->io_outputb(kcs_bmc, kcs_bmc->ioreg.odr, data);
> }
> EXPORT_SYMBOL(kcs_bmc_write_data);
>
> u8 kcs_bmc_read_status(struct kcs_bmc *kcs_bmc)
> {
>-	return kcs_bmc->io_inputb(kcs_bmc, kcs_bmc->ioreg.str);
>+	return kcs_bmc->ops->io_inputb(kcs_bmc, kcs_bmc->ioreg.str);
> }
> EXPORT_SYMBOL(kcs_bmc_read_status);
>
> void kcs_bmc_write_status(struct kcs_bmc *kcs_bmc, u8 data)
> {
>-	kcs_bmc->io_outputb(kcs_bmc, kcs_bmc->ioreg.str, data);
>+	kcs_bmc->ops->io_outputb(kcs_bmc, kcs_bmc->ioreg.str, data);
> }
> EXPORT_SYMBOL(kcs_bmc_write_status);
>
> void kcs_bmc_update_status(struct kcs_bmc *kcs_bmc, u8 mask, u8 val)
> {
>-	kcs_bmc->io_updateb(kcs_bmc, kcs_bmc->ioreg.str, mask, val);
>+	kcs_bmc->ops->io_updateb(kcs_bmc, kcs_bmc->ioreg.str, mask, val);
> }
> EXPORT_SYMBOL(kcs_bmc_update_status);
>
>-int kcs_bmc_ipmi_event(struct kcs_bmc *kcs_bmc);
>-int kcs_bmc_handle_event(struct kcs_bmc *kcs_bmc)
>+irqreturn_t kcs_bmc_handle_event(struct kcs_bmc *kcs_bmc)
> {
>-	return kcs_bmc_ipmi_event(kcs_bmc);
>+	return kcs_bmc->client.ops->event(&kcs_bmc->client);
> }
> EXPORT_SYMBOL(kcs_bmc_handle_event);
>
>@@ -64,4 +70,5 @@ EXPORT_SYMBOL(kcs_bmc_remove_device);
>
> MODULE_LICENSE("GPL v2");
> MODULE_AUTHOR("Haiyue Wang <[email-masked]>");
>+MODULE_AUTHOR("Andrew Jeffery <[email-masked]>");
> MODULE_DESCRIPTION("KCS BMC to handle the IPMI request from system software");
>diff --git a/drivers/char/ipmi/kcs_bmc.h b/drivers/char/ipmi/kcs_bmc.h
>index b2e6b7a7fe62..f42843d240ed 100644
>--- a/drivers/char/ipmi/kcs_bmc.h
>+++ b/drivers/char/ipmi/kcs_bmc.h
>@@ -8,6 +8,12 @@
>
> #include <linux/miscdevice.h>
>
>+#include "kcs_bmc_client.h"
>+
>+#define KCS_BMC_STR_OBF		BIT(0)
>+#define KCS_BMC_STR_IBF		BIT(1)
>+#define KCS_BMC_STR_CMD_DAT	BIT(3)
>+
> /* Different phases of the KCS BMC module.
>  *  KCS_PHASE_IDLE:
>  *            BMC should not be expecting nor sending any data.
>@@ -66,19 +72,21 @@ struct kcs_ioreg {
> 	u32 str;
> };
>
>+struct kcs_bmc_device_ops;
>+
> struct kcs_bmc {
> 	struct device *dev;
>
>+	const struct kcs_bmc_device_ops *ops;
>+
>+	struct kcs_bmc_client client;
>+
> 	spinlock_t lock;
>
> 	u32 channel;
> 	int running;
>
>-	/* Setup by BMC KCS controller driver */
> 	struct kcs_ioreg ioreg;
>-	u8 (*io_inputb)(struct kcs_bmc *kcs_bmc, u32 reg);
>-	void (*io_outputb)(struct kcs_bmc *kcs_bmc, u32 reg, u8 b);
>-	void (*io_updateb)(struct kcs_bmc *kcs_bmc, u32 reg, u8 mask, u8 val);
>
> 	enum kcs_phases phase;
> 	enum kcs_errors error;
>@@ -97,15 +105,4 @@ struct kcs_bmc {
>
> 	struct miscdevice miscdev;
> };
>-
>-int kcs_bmc_handle_event(struct kcs_bmc *kcs_bmc);
>-void kcs_bmc_add_device(struct kcs_bmc *kcs_bmc);
>-void kcs_bmc_remove_device(struct kcs_bmc *kcs_bmc);
>-
>-u8 kcs_bmc_read_data(struct kcs_bmc *kcs_bmc);
>-void kcs_bmc_write_data(struct kcs_bmc *kcs_bmc, u8 data);
>-u8 kcs_bmc_read_status(struct kcs_bmc *kcs_bmc);
>-void kcs_bmc_write_status(struct kcs_bmc *kcs_bmc, u8 data);
>-void kcs_bmc_update_status(struct kcs_bmc *kcs_bmc, u8 mask, u8 val);
>-
> #endif /* __KCS_BMC_H__ */
>diff --git a/drivers/char/ipmi/kcs_bmc_aspeed.c b/drivers/char/ipmi/kcs_bmc_aspeed.c
>index 5d433dea5714..337b69cea1da 100644
>--- a/drivers/char/ipmi/kcs_bmc_aspeed.c
>+++ b/drivers/char/ipmi/kcs_bmc_aspeed.c
>@@ -21,7 +21,7 @@
> #include <linux/slab.h>
> #include <linux/timer.h>
>
>-#include "kcs_bmc.h"
>+#include "kcs_bmc_device.h"
>
>
> #define DEVICE_NAME     "ast-kcs-bmc"
>@@ -220,14 +220,17 @@ static void aspeed_kcs_enable_channel(struct kcs_bmc *kcs_bmc, bool enable)
> 	}
> }
>
>+static const struct kcs_bmc_device_ops aspeed_kcs_ops = {
>+	.io_inputb = aspeed_kcs_inb,
>+	.io_outputb = aspeed_kcs_outb,
>+	.io_updateb = aspeed_kcs_updateb,
>+};
>+
> static irqreturn_t aspeed_kcs_irq(int irq, void *arg)
> {
> 	struct kcs_bmc *kcs_bmc = arg;
>
>-	if (!kcs_bmc_handle_event(kcs_bmc))
>-		return IRQ_HANDLED;
>-
>-	return IRQ_NONE;
>+	return kcs_bmc_handle_event(kcs_bmc);
> }
>
> static int aspeed_kcs_config_irq(struct kcs_bmc *kcs_bmc,
>@@ -362,9 +365,7 @@ static int aspeed_kcs_probe(struct platform_device *pdev)
> 	kcs_bmc->dev = &pdev->dev;
> 	kcs_bmc->channel = channel;
> 	kcs_bmc->ioreg = ast_kcs_bmc_ioregs[channel - 1];
>-	kcs_bmc->io_inputb = aspeed_kcs_inb;
>-	kcs_bmc->io_outputb = aspeed_kcs_outb;
>-	kcs_bmc->io_updateb = aspeed_kcs_updateb;
>+	kcs_bmc->ops = &aspeed_kcs_ops;
>
> 	priv->map = syscon_node_to_regmap(pdev->dev.parent->of_node);
> 	if (IS_ERR(priv->map)) {
>diff --git a/drivers/char/ipmi/kcs_bmc_cdev_ipmi.c b/drivers/char/ipmi/kcs_bmc_cdev_ipmi.c
>index 5060643bf530..476ad6d541d5 100644
>--- a/drivers/char/ipmi/kcs_bmc_cdev_ipmi.c
>+++ b/drivers/char/ipmi/kcs_bmc_cdev_ipmi.c
>@@ -22,7 +22,6 @@
>
> #define KCS_ZERO_DATA     0
>
>-
> /* IPMI 2.0 - Table 9-1, KCS Interface Status Register Bits */
> #define KCS_STATUS_STATE(state) (state << 6)
> #define KCS_STATUS_STATE_MASK   GENMASK(7, 6)
>@@ -179,12 +178,19 @@ static void kcs_bmc_ipmi_handle_cmd(struct kcs_bmc *kcs_bmc)
> 	}
> }
>
>-int kcs_bmc_ipmi_event(struct kcs_bmc *kcs_bmc);
>-int kcs_bmc_ipmi_event(struct kcs_bmc *kcs_bmc)
>+static inline struct kcs_bmc *client_to_kcs_bmc(struct kcs_bmc_client *client)
> {
>+	return container_of(client, struct kcs_bmc, client);
>+}
>+
>+static irqreturn_t kcs_bmc_ipmi_event(struct kcs_bmc_client *client)
>+{
>+	struct kcs_bmc *kcs_bmc;
> 	unsigned long flags;
>-	int ret = -ENODATA;
> 	u8 status;
>+	int ret;
>+
>+	kcs_bmc = client_to_kcs_bmc(client);
>
> 	spin_lock_irqsave(&kcs_bmc->lock, flags);
>
>@@ -197,23 +203,28 @@ int kcs_bmc_ipmi_event(struct kcs_bmc *kcs_bmc)
> 		else
> 			kcs_bmc_ipmi_handle_data(kcs_bmc);
>
>-		ret = 0;
>+		ret = IRQ_HANDLED;
>+	} else {
>+		ret = IRQ_NONE;
> 	}
>
> 	spin_unlock_irqrestore(&kcs_bmc->lock, flags);
>
> 	return ret;
> }
>-EXPORT_SYMBOL(kcs_bmc_ipmi_event);
>
>-static inline struct kcs_bmc *to_kcs_bmc(struct file *filp)
>+static const struct kcs_bmc_client_ops kcs_bmc_ipmi_client_ops = {
>+	.event = kcs_bmc_ipmi_event,
>+};
>+
>+static inline struct kcs_bmc *file_to_kcs_bmc(struct file *filp)
> {
> 	return container_of(filp->private_data, struct kcs_bmc, miscdev);
> }
>
> static int kcs_bmc_ipmi_open(struct inode *inode, struct file *filp)
> {
>-	struct kcs_bmc *kcs_bmc = to_kcs_bmc(filp);
>+	struct kcs_bmc *kcs_bmc = file_to_kcs_bmc(filp);
> 	int ret = 0;
>
> 	spin_lock_irq(&kcs_bmc->lock);
>@@ -228,7 +239,7 @@ static int kcs_bmc_ipmi_open(struct inode *inode, struct file *filp)
>
> static __poll_t kcs_bmc_ipmi_poll(struct file *filp, poll_table *wait)
> {
>-	struct kcs_bmc *kcs_bmc = to_kcs_bmc(filp);
>+	struct kcs_bmc *kcs_bmc = file_to_kcs_bmc(filp);
> 	__poll_t mask = 0;
>
> 	poll_wait(filp, &kcs_bmc->queue, wait);
>@@ -244,7 +255,7 @@ static __poll_t kcs_bmc_ipmi_poll(struct file *filp, poll_table *wait)
> static ssize_t kcs_bmc_ipmi_read(struct file *filp, char __user *buf,
> 			    size_t count, loff_t *ppos)
> {
>-	struct kcs_bmc *kcs_bmc = to_kcs_bmc(filp);
>+	struct kcs_bmc *kcs_bmc = file_to_kcs_bmc(filp);
> 	bool data_avail;
> 	size_t data_len;
> 	ssize_t ret;
>@@ -306,7 +317,7 @@ static ssize_t kcs_bmc_ipmi_read(struct file *filp, char __user *buf,
> static ssize_t kcs_bmc_ipmi_write(struct file *filp, const char __user *buf,
> 			     size_t count, loff_t *ppos)
> {
>-	struct kcs_bmc *kcs_bmc = to_kcs_bmc(filp);
>+	struct kcs_bmc *kcs_bmc = file_to_kcs_bmc(filp);
> 	ssize_t ret;
>
> 	/* a minimum response size '3' : netfn + cmd + ccode */
>@@ -342,7 +353,7 @@ static ssize_t kcs_bmc_ipmi_write(struct file *filp, const char __user *buf,
> static long kcs_bmc_ipmi_ioctl(struct file *filp, unsigned int cmd,
> 			  unsigned long arg)
> {
>-	struct kcs_bmc *kcs_bmc = to_kcs_bmc(filp);
>+	struct kcs_bmc *kcs_bmc = file_to_kcs_bmc(filp);
> 	long ret = 0;
>
> 	spin_lock_irq(&kcs_bmc->lock);
>@@ -372,7 +383,7 @@ static long kcs_bmc_ipmi_ioctl(struct file *filp, unsigned int cmd,
>
> static int kcs_bmc_ipmi_release(struct inode *inode, struct file *filp)
> {
>-	struct kcs_bmc *kcs_bmc = to_kcs_bmc(filp);
>+	struct kcs_bmc *kcs_bmc = file_to_kcs_bmc(filp);
>
> 	spin_lock_irq(&kcs_bmc->lock);
> 	kcs_bmc->running = 0;
>@@ -401,6 +412,8 @@ int kcs_bmc_ipmi_add_device(struct kcs_bmc *kcs_bmc)
> 	mutex_init(&kcs_bmc->mutex);
> 	init_waitqueue_head(&kcs_bmc->queue);
>
>+	kcs_bmc->client.dev = kcs_bmc;
>+	kcs_bmc->client.ops = &kcs_bmc_ipmi_client_ops;
> 	kcs_bmc->data_in = devm_kmalloc(kcs_bmc->dev, KCS_MSG_BUFSIZ, GFP_KERNEL);
> 	kcs_bmc->data_out = devm_kmalloc(kcs_bmc->dev, KCS_MSG_BUFSIZ, GFP_KERNEL);
> 	kcs_bmc->kbuffer = devm_kmalloc(kcs_bmc->dev, KCS_MSG_BUFSIZ, GFP_KERNEL);
>diff --git a/drivers/char/ipmi/kcs_bmc_client.h b/drivers/char/ipmi/kcs_bmc_client.h
>new file mode 100644
>index 000000000000..b19a7ff64b80
>--- /dev/null
>+++ b/drivers/char/ipmi/kcs_bmc_client.h
>@@ -0,0 +1,30 @@
>+/* SPDX-License-Identifier: GPL-2.0 */
>+/* Copyright (c) 2021, IBM Corp. */
>+
>+#ifndef __KCS_BMC_CONSUMER_H__
>+#define __KCS_BMC_CONSUMER_H__
>+
>+#include <linux/irqreturn.h>
>+#include <linux/list.h>
>+#include <linux/notifier.h>
>+#include <stdbool.h>

Unless there's something non-obvious going on here, I'd think just
linux/irqreturn.h and linux/types.h would suffice for this header?  (I
don't see any lists or notifiers or bools, anyway.)

[...reads ahead...]

Ah, I guess eventually patch #8 adds a list_head, but I suppose it'd be
preferable to add the list.h #include in that patch instead of this one.

>+
>+struct kcs_bmc;
>+struct kcs_bmc_client_ops;
>+
>+struct kcs_bmc_client {
>+	const struct kcs_bmc_client_ops *ops;
>+
>+	struct kcs_bmc *dev;
>+};
>+
>+struct kcs_bmc_client_ops {
>+	irqreturn_t (*event)(struct kcs_bmc_client *client);
>+};
>+
>+u8 kcs_bmc_read_data(struct kcs_bmc *kcs_bmc);
>+void kcs_bmc_write_data(struct kcs_bmc *kcs_bmc, u8 data);
>+u8 kcs_bmc_read_status(struct kcs_bmc *kcs_bmc);
>+void kcs_bmc_write_status(struct kcs_bmc *kcs_bmc, u8 data);
>+void kcs_bmc_update_status(struct kcs_bmc *kcs_bmc, u8 mask, u8 val);
>+#endif
>diff --git a/drivers/char/ipmi/kcs_bmc_device.h b/drivers/char/ipmi/kcs_bmc_device.h
>new file mode 100644
>index 000000000000..14f8d700a3d8
>--- /dev/null
>+++ b/drivers/char/ipmi/kcs_bmc_device.h
>@@ -0,0 +1,19 @@
>+/* SPDX-License-Identifier: GPL-2.0 */
>+/* Copyright (c) 2021, IBM Corp. */
>+
>+#ifndef __KCS_BMC_DEVICE_H__
>+#define __KCS_BMC_DEVICE_H__
>+
>+#include "kcs_bmc.h"
>+
>+struct kcs_bmc_device_ops {
>+	u8 (*io_inputb)(struct kcs_bmc *kcs_bmc, u32 reg);
>+	void (*io_outputb)(struct kcs_bmc *kcs_bmc, u32 reg, u8 b);
>+	void (*io_updateb)(struct kcs_bmc *kcs_bmc, u32 reg, u8 mask, u8 b);
>+};
>+
>+irqreturn_t kcs_bmc_handle_event(struct kcs_bmc *kcs_bmc);
>+void kcs_bmc_add_device(struct kcs_bmc *kcs_bmc);
>+void kcs_bmc_remove_device(struct kcs_bmc *kcs_bmc);
>+
>+#endif
>diff --git a/drivers/char/ipmi/kcs_bmc_npcm7xx.c b/drivers/char/ipmi/kcs_bmc_npcm7xx.c
>index f7b4e866f86e..203258b24708 100644
>--- a/drivers/char/ipmi/kcs_bmc_npcm7xx.c
>+++ b/drivers/char/ipmi/kcs_bmc_npcm7xx.c
>@@ -17,7 +17,7 @@
> #include <linux/regmap.h>
> #include <linux/slab.h>
>
>-#include "kcs_bmc.h"
>+#include "kcs_bmc_device.h"
>
> #define DEVICE_NAME	"npcm-kcs-bmc"
> #define KCS_CHANNEL_MAX	3
>@@ -128,10 +128,7 @@ static irqreturn_t npcm7xx_kcs_irq(int irq, void *arg)
> {
> 	struct kcs_bmc *kcs_bmc = arg;
>
>-	if (!kcs_bmc_handle_event(kcs_bmc))
>-		return IRQ_HANDLED;
>-
>-	return IRQ_NONE;
>+	return kcs_bmc_handle_event(kcs_bmc);
> }
>
> static int npcm7xx_kcs_config_irq(struct kcs_bmc *kcs_bmc,
>@@ -148,6 +145,12 @@ static int npcm7xx_kcs_config_irq(struct kcs_bmc *kcs_bmc,
> 				dev_name(dev), kcs_bmc);
> }
>
>+static const struct kcs_bmc_device_ops npcm7xx_kcs_ops = {
>+	.io_inputb = npcm7xx_kcs_inb,
>+	.io_outputb = npcm7xx_kcs_outb,
>+	.io_updateb = npcm7xx_kcs_updateb,
>+};
>+
> static int npcm7xx_kcs_probe(struct platform_device *pdev)
> {
> 	struct device *dev = &pdev->dev;
>@@ -179,9 +182,7 @@ static int npcm7xx_kcs_probe(struct platform_device *pdev)
> 	kcs_bmc->ioreg.idr = priv->reg->dib;
> 	kcs_bmc->ioreg.odr = priv->reg->dob;
> 	kcs_bmc->ioreg.str = priv->reg->sts;
>-	kcs_bmc->io_inputb = npcm7xx_kcs_inb;
>-	kcs_bmc->io_outputb = npcm7xx_kcs_outb;
>-	kcs_bmc->io_updateb = npcm7xx_kcs_updateb;
>+	kcs_bmc->ops = &npcm7xx_kcs_ops;
>
> 	platform_set_drvdata(pdev, priv);
>
>-- 
>2.27.0
>
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