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From:   Andrew Jeffery <andrew@aj.id.au>
To:     openipmi-developer@lists.sourceforge.net, openbmc@lists.ozlabs.org,
        minyard@acm.org
Cc:     joel@jms.id.au, ryan_chen@aspeedtech.com,
        devicetree@vger.kernel.org, tmaimon77@gmail.com,
        linux-aspeed@lists.ozlabs.org, linux-gpio@vger.kernel.org,
        avifishman70@gmail.com, venture@google.com,
        linus.walleij@linaro.org, linux-kernel@vger.kernel.org,
        tali.perry1@gmail.com, robh+dt@kernel.org, lee.jones@linaro.org,
        chiawei_wang@aspeedtech.com, linux-arm-kernel@lists.infradead.org,
        benjaminfair@google.com
Subject: [PATCH v2 10/21] ipmi: kcs_bmc: Turn the driver data-structures inside-out
Date:   Fri, 19 Mar 2021 16:57:41 +1030
Message-Id: <20210319062752.145730-10-andrew@aj.id.au>
In-Reply-To: <20210319062752.145730-1-andrew@aj.id.au>
References: <20210319062752.145730-1-andrew@aj.id.au>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

Make the KCS device drivers responsible for allocating their own memory.

Until now the private data for the device driver was allocated internal
to the private data for the chardev interface. This coupling required
the slightly awkward API of passing through the struct size for the
driver private data to the chardev constructor, and then retrieving a
pointer to the driver private data from the allocated chardev memory.

In addition to being awkward, the arrangement prevents the
implementation of alternative userspace interfaces as the device driver
private data is not independent.

Peel a layer off the onion and turn the data-structures inside out by
exploiting container_of() and embedding `struct kcs_device` in the
driver private data.

Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
---
 drivers/char/ipmi/kcs_bmc.c           | 15 +++++--
 drivers/char/ipmi/kcs_bmc.h           | 12 ++----
 drivers/char/ipmi/kcs_bmc_aspeed.c    | 60 ++++++++++++++++-----------
 drivers/char/ipmi/kcs_bmc_cdev_ipmi.c | 60 ++++++++++++++++++---------
 drivers/char/ipmi/kcs_bmc_npcm7xx.c   | 37 ++++++++++-------
 5 files changed, 113 insertions(+), 71 deletions(-)

diff --git a/drivers/char/ipmi/kcs_bmc.c b/drivers/char/ipmi/kcs_bmc.c
index ef5c48ffe74a..709b6bdec165 100644
--- a/drivers/char/ipmi/kcs_bmc.c
+++ b/drivers/char/ipmi/kcs_bmc.c
@@ -44,12 +44,19 @@ int kcs_bmc_handle_event(struct kcs_bmc *kcs_bmc)
 }
 EXPORT_SYMBOL(kcs_bmc_handle_event);
 
-struct kcs_bmc *kcs_bmc_ipmi_alloc(struct device *dev, int sizeof_priv, u32 channel);
-struct kcs_bmc *kcs_bmc_alloc(struct device *dev, int sizeof_priv, u32 channel)
+int kcs_bmc_ipmi_attach_cdev(struct kcs_bmc *kcs_bmc);
+int kcs_bmc_add_device(struct kcs_bmc *kcs_bmc)
 {
-	return kcs_bmc_ipmi_alloc(dev, sizeof_priv, channel);
+	return kcs_bmc_ipmi_attach_cdev(kcs_bmc);
 }
-EXPORT_SYMBOL(kcs_bmc_alloc);
+EXPORT_SYMBOL(kcs_bmc_add_device);
+
+int kcs_bmc_ipmi_detach_cdev(struct kcs_bmc *kcs_bmc);
+int kcs_bmc_remove_device(struct kcs_bmc *kcs_bmc)
+{
+	return kcs_bmc_ipmi_detach_cdev(kcs_bmc);
+}
+EXPORT_SYMBOL(kcs_bmc_remove_device);
 
 MODULE_LICENSE("GPL v2");
 MODULE_AUTHOR("Haiyue Wang <haiyue.wang@linux.intel.com>");
diff --git a/drivers/char/ipmi/kcs_bmc.h b/drivers/char/ipmi/kcs_bmc.h
index febea0c8deb4..bf0ae327997f 100644
--- a/drivers/char/ipmi/kcs_bmc.h
+++ b/drivers/char/ipmi/kcs_bmc.h
@@ -67,6 +67,8 @@ struct kcs_ioreg {
 };
 
 struct kcs_bmc {
+	struct device *dev;
+
 	spinlock_t lock;
 
 	u32 channel;
@@ -94,17 +96,11 @@ struct kcs_bmc {
 	u8 *kbuffer;
 
 	struct miscdevice miscdev;
-
-	unsigned long priv[];
 };
 
-static inline void *kcs_bmc_priv(struct kcs_bmc *kcs_bmc)
-{
-	return kcs_bmc->priv;
-}
-
 int kcs_bmc_handle_event(struct kcs_bmc *kcs_bmc);
-struct kcs_bmc *kcs_bmc_alloc(struct device *dev, int sizeof_priv, u32 channel);
+int kcs_bmc_add_device(struct kcs_bmc *kcs_bmc);
+int 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);
diff --git a/drivers/char/ipmi/kcs_bmc_aspeed.c b/drivers/char/ipmi/kcs_bmc_aspeed.c
index 630cf095560e..0416ac78ce68 100644
--- a/drivers/char/ipmi/kcs_bmc_aspeed.c
+++ b/drivers/char/ipmi/kcs_bmc_aspeed.c
@@ -61,6 +61,8 @@
 #define LPC_STR4             0x11C
 
 struct aspeed_kcs_bmc {
+	struct kcs_bmc kcs_bmc;
+
 	struct regmap *map;
 };
 
@@ -69,9 +71,14 @@ struct aspeed_kcs_of_ops {
 	int (*get_io_address)(struct platform_device *pdev);
 };
 
+static inline struct aspeed_kcs_bmc *to_aspeed_kcs_bmc(struct kcs_bmc *kcs_bmc)
+{
+	return container_of(kcs_bmc, struct aspeed_kcs_bmc, kcs_bmc);
+}
+
 static u8 aspeed_kcs_inb(struct kcs_bmc *kcs_bmc, u32 reg)
 {
-	struct aspeed_kcs_bmc *priv = kcs_bmc_priv(kcs_bmc);
+	struct aspeed_kcs_bmc *priv = to_aspeed_kcs_bmc(kcs_bmc);
 	u32 val = 0;
 	int rc;
 
@@ -83,7 +90,7 @@ static u8 aspeed_kcs_inb(struct kcs_bmc *kcs_bmc, u32 reg)
 
 static void aspeed_kcs_outb(struct kcs_bmc *kcs_bmc, u32 reg, u8 data)
 {
-	struct aspeed_kcs_bmc *priv = kcs_bmc_priv(kcs_bmc);
+	struct aspeed_kcs_bmc *priv = to_aspeed_kcs_bmc(kcs_bmc);
 	int rc;
 
 	rc = regmap_write(priv->map, reg, data);
@@ -92,7 +99,7 @@ static void aspeed_kcs_outb(struct kcs_bmc *kcs_bmc, u32 reg, u8 data)
 
 static void aspeed_kcs_updateb(struct kcs_bmc *kcs_bmc, u32 reg, u8 mask, u8 val)
 {
-	struct aspeed_kcs_bmc *priv = kcs_bmc_priv(kcs_bmc);
+	struct aspeed_kcs_bmc *priv = to_aspeed_kcs_bmc(kcs_bmc);
 	int rc;
 
 	rc = regmap_update_bits(priv->map, reg, mask, val);
@@ -114,7 +121,7 @@ static void aspeed_kcs_updateb(struct kcs_bmc *kcs_bmc, u32 reg, u8 mask, u8 val
  */
 static void aspeed_kcs_set_address(struct kcs_bmc *kcs_bmc, u16 addr)
 {
-	struct aspeed_kcs_bmc *priv = kcs_bmc_priv(kcs_bmc);
+	struct aspeed_kcs_bmc *priv = to_aspeed_kcs_bmc(kcs_bmc);
 
 	switch (kcs_bmc->channel) {
 	case 1:
@@ -148,7 +155,7 @@ static void aspeed_kcs_set_address(struct kcs_bmc *kcs_bmc, u16 addr)
 
 static void aspeed_kcs_enable_channel(struct kcs_bmc *kcs_bmc, bool enable)
 {
-	struct aspeed_kcs_bmc *priv = kcs_bmc_priv(kcs_bmc);
+	struct aspeed_kcs_bmc *priv = to_aspeed_kcs_bmc(kcs_bmc);
 
 	switch (kcs_bmc->channel) {
 	case 1:
@@ -323,16 +330,16 @@ static int aspeed_kcs_of_v2_get_io_address(struct platform_device *pdev)
 static int aspeed_kcs_probe(struct platform_device *pdev)
 {
 	const struct aspeed_kcs_of_ops *ops;
-	struct device *dev = &pdev->dev;
+	struct aspeed_kcs_bmc *priv;
 	struct kcs_bmc *kcs_bmc;
 	struct device_node *np;
 	int rc, channel, addr;
 
-	np = dev->of_node->parent;
+	np = pdev->dev.of_node->parent;
 	if (!of_device_is_compatible(np, "aspeed,ast2400-lpc-v2") &&
 	    !of_device_is_compatible(np, "aspeed,ast2500-lpc-v2") &&
 	    !of_device_is_compatible(np, "aspeed,ast2600-lpc-v2")) {
-		dev_err(dev, "unsupported LPC device binding\n");
+		dev_err(&pdev->dev, "unsupported LPC device binding\n");
 		return -ENODEV;
 	}
 	ops = of_device_get_match_data(&pdev->dev);
@@ -343,18 +350,27 @@ static int aspeed_kcs_probe(struct platform_device *pdev)
 	if (channel < 0)
 		return channel;
 
-	kcs_bmc = kcs_bmc_alloc(&pdev->dev, sizeof(struct aspeed_kcs_bmc), channel);
-	if (!kcs_bmc)
+	addr = ops->get_io_address(pdev);
+	if (addr < 0)
+		return addr;
+
+	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
 		return -ENOMEM;
 
+	kcs_bmc = &priv->kcs_bmc;
+	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;
 
-	addr = ops->get_io_address(pdev);
-	if (addr < 0)
-		return addr;
+	priv->map = syscon_node_to_regmap(pdev->dev.parent->of_node);
+	if (IS_ERR(priv->map)) {
+		dev_err(&pdev->dev, "Couldn't get regmap\n");
+		return -ENODEV;
+	}
 
 	aspeed_kcs_set_address(kcs_bmc, addr);
 
@@ -362,29 +378,25 @@ static int aspeed_kcs_probe(struct platform_device *pdev)
 	if (rc)
 		return rc;
 
-	dev_set_drvdata(dev, kcs_bmc);
+	platform_set_drvdata(pdev, priv);
 
 	aspeed_kcs_enable_channel(kcs_bmc, true);
 
-	rc = misc_register(&kcs_bmc->miscdev);
-	if (rc) {
-		dev_err(dev, "Unable to register device\n");
+	rc = kcs_bmc_add_device(&priv->kcs_bmc);
+	if (rc < 0)
 		return rc;
-	}
 
-	dev_dbg(&pdev->dev,
-		"Probed KCS device %d (IDR=0x%x, ODR=0x%x, STR=0x%x)\n",
-		kcs_bmc->channel, kcs_bmc->ioreg.idr, kcs_bmc->ioreg.odr,
-		kcs_bmc->ioreg.str);
+	dev_info(&pdev->dev, "Initialised channel %d at 0x%x\n", kcs_bmc->channel, addr);
 
 	return 0;
 }
 
 static int aspeed_kcs_remove(struct platform_device *pdev)
 {
-	struct kcs_bmc *kcs_bmc = dev_get_drvdata(&pdev->dev);
+	struct aspeed_kcs_bmc *priv = platform_get_drvdata(pdev);
+	struct kcs_bmc *kcs_bmc = &priv->kcs_bmc;
 
-	misc_deregister(&kcs_bmc->miscdev);
+	kcs_bmc_remove_device(kcs_bmc);
 
 	return 0;
 }
diff --git a/drivers/char/ipmi/kcs_bmc_cdev_ipmi.c b/drivers/char/ipmi/kcs_bmc_cdev_ipmi.c
index 82c77994e481..0ca71c135a1a 100644
--- a/drivers/char/ipmi/kcs_bmc_cdev_ipmi.c
+++ b/drivers/char/ipmi/kcs_bmc_cdev_ipmi.c
@@ -382,7 +382,7 @@ static int kcs_bmc_ipmi_release(struct inode *inode, struct file *filp)
 	return 0;
 }
 
-static const struct file_operations kcs_bmc_fops = {
+static const struct file_operations kcs_bmc_ipmi_fops = {
 	.owner          = THIS_MODULE,
 	.open           = kcs_bmc_ipmi_open,
 	.read           = kcs_bmc_ipmi_read,
@@ -392,36 +392,58 @@ static const struct file_operations kcs_bmc_fops = {
 	.unlocked_ioctl = kcs_bmc_ipmi_ioctl,
 };
 
-struct kcs_bmc *kcs_bmc_ipmi_alloc(struct device *dev, int sizeof_priv, u32 channel);
-struct kcs_bmc *kcs_bmc_ipmi_alloc(struct device *dev, int sizeof_priv, u32 channel)
+int kcs_bmc_ipmi_attach_cdev(struct kcs_bmc *kcs_bmc);
+int kcs_bmc_ipmi_attach_cdev(struct kcs_bmc *kcs_bmc)
 {
-	struct kcs_bmc *kcs_bmc;
-
-	kcs_bmc = devm_kzalloc(dev, sizeof(*kcs_bmc) + sizeof_priv, GFP_KERNEL);
-	if (!kcs_bmc)
-		return NULL;
+	int rc;
 
 	spin_lock_init(&kcs_bmc->lock);
-	kcs_bmc->channel = channel;
-
 	mutex_init(&kcs_bmc->mutex);
 	init_waitqueue_head(&kcs_bmc->queue);
 
-	kcs_bmc->data_in = devm_kmalloc(dev, KCS_MSG_BUFSIZ, GFP_KERNEL);
-	kcs_bmc->data_out = devm_kmalloc(dev, KCS_MSG_BUFSIZ, GFP_KERNEL);
-	kcs_bmc->kbuffer = devm_kmalloc(dev, KCS_MSG_BUFSIZ, GFP_KERNEL);
+	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);
 
 	kcs_bmc->miscdev.minor = MISC_DYNAMIC_MINOR;
-	kcs_bmc->miscdev.name = devm_kasprintf(dev, GFP_KERNEL, "%s%u",
-					       DEVICE_NAME, channel);
+	kcs_bmc->miscdev.name = devm_kasprintf(kcs_bmc->dev, GFP_KERNEL, "%s%u",
+					       DEVICE_NAME, kcs_bmc->channel);
 	if (!kcs_bmc->data_in || !kcs_bmc->data_out || !kcs_bmc->kbuffer ||
 	    !kcs_bmc->miscdev.name)
-		return NULL;
-	kcs_bmc->miscdev.fops = &kcs_bmc_fops;
+		return -ENOMEM;
 
-	return kcs_bmc;
+	kcs_bmc->miscdev.fops = &kcs_bmc_ipmi_fops;
+
+	rc = misc_register(&kcs_bmc->miscdev);
+	if (rc) {
+		dev_err(kcs_bmc->dev, "Unable to register device: %d\n", rc);
+		return rc;
+	}
+
+	dev_info(kcs_bmc->dev, "Initialised IPMI client for channel %d", kcs_bmc->channel);
+
+	return 0;
+}
+EXPORT_SYMBOL(kcs_bmc_ipmi_attach_cdev);
+
+int kcs_bmc_ipmi_detach_cdev(struct kcs_bmc *kcs_bmc);
+int kcs_bmc_ipmi_detach_cdev(struct kcs_bmc *kcs_bmc)
+{
+	misc_deregister(&kcs_bmc->miscdev);
+
+	spin_lock_irq(&kcs_bmc->lock);
+	kcs_bmc->running = 0;
+	kcs_bmc_ipmi_force_abort(kcs_bmc);
+	spin_unlock_irq(&kcs_bmc->lock);
+
+	devm_kfree(kcs_bmc->dev, kcs_bmc->kbuffer);
+	devm_kfree(kcs_bmc->dev, kcs_bmc->data_out);
+	devm_kfree(kcs_bmc->dev, kcs_bmc->data_in);
+	devm_kfree(kcs_bmc->dev, kcs_bmc);
+
+	return 0;
 }
-EXPORT_SYMBOL(kcs_bmc_ipmi_alloc);
+EXPORT_SYMBOL(kcs_bmc_ipmi_detach_cdev);
 
 MODULE_LICENSE("GPL v2");
 MODULE_AUTHOR("Haiyue Wang <haiyue.wang@linux.intel.com>");
diff --git a/drivers/char/ipmi/kcs_bmc_npcm7xx.c b/drivers/char/ipmi/kcs_bmc_npcm7xx.c
index 1f44aadec9e8..5d017498dc69 100644
--- a/drivers/char/ipmi/kcs_bmc_npcm7xx.c
+++ b/drivers/char/ipmi/kcs_bmc_npcm7xx.c
@@ -65,6 +65,8 @@ struct npcm7xx_kcs_reg {
 };
 
 struct npcm7xx_kcs_bmc {
+	struct kcs_bmc kcs_bmc;
+
 	struct regmap *map;
 
 	const struct npcm7xx_kcs_reg *reg;
@@ -76,9 +78,14 @@ static const struct npcm7xx_kcs_reg npcm7xx_kcs_reg_tbl[KCS_CHANNEL_MAX] = {
 	{ .sts = KCS3ST, .dob = KCS3DO, .dib = KCS3DI, .ctl = KCS3CTL, .ie = KCS3IE },
 };
 
+static inline struct npcm7xx_kcs_bmc *to_npcm7xx_kcs_bmc(struct kcs_bmc *kcs_bmc)
+{
+	return container_of(kcs_bmc, struct npcm7xx_kcs_bmc, kcs_bmc);
+}
+
 static u8 npcm7xx_kcs_inb(struct kcs_bmc *kcs_bmc, u32 reg)
 {
-	struct npcm7xx_kcs_bmc *priv = kcs_bmc_priv(kcs_bmc);
+	struct npcm7xx_kcs_bmc *priv = to_npcm7xx_kcs_bmc(kcs_bmc);
 	u32 val = 0;
 	int rc;
 
@@ -90,7 +97,7 @@ static u8 npcm7xx_kcs_inb(struct kcs_bmc *kcs_bmc, u32 reg)
 
 static void npcm7xx_kcs_outb(struct kcs_bmc *kcs_bmc, u32 reg, u8 data)
 {
-	struct npcm7xx_kcs_bmc *priv = kcs_bmc_priv(kcs_bmc);
+	struct npcm7xx_kcs_bmc *priv = to_npcm7xx_kcs_bmc(kcs_bmc);
 	int rc;
 
 	rc = regmap_write(priv->map, reg, data);
@@ -99,7 +106,7 @@ static void npcm7xx_kcs_outb(struct kcs_bmc *kcs_bmc, u32 reg, u8 data)
 
 static void npcm7xx_kcs_updateb(struct kcs_bmc *kcs_bmc, u32 reg, u8 mask, u8 data)
 {
-	struct npcm7xx_kcs_bmc *priv = kcs_bmc_priv(kcs_bmc);
+	struct npcm7xx_kcs_bmc *priv = to_npcm7xx_kcs_bmc(kcs_bmc);
 	int rc;
 
 	rc = regmap_update_bits(priv->map, reg, mask, data);
@@ -108,7 +115,7 @@ static void npcm7xx_kcs_updateb(struct kcs_bmc *kcs_bmc, u32 reg, u8 mask, u8 da
 
 static void npcm7xx_kcs_enable_channel(struct kcs_bmc *kcs_bmc, bool enable)
 {
-	struct npcm7xx_kcs_bmc *priv = kcs_bmc_priv(kcs_bmc);
+	struct npcm7xx_kcs_bmc *priv = to_npcm7xx_kcs_bmc(kcs_bmc);
 
 	regmap_update_bits(priv->map, priv->reg->ctl, KCS_CTL_IBFIE,
 			   enable ? KCS_CTL_IBFIE : 0);
@@ -155,11 +162,10 @@ static int npcm7xx_kcs_probe(struct platform_device *pdev)
 		return -ENODEV;
 	}
 
-	kcs_bmc = kcs_bmc_alloc(dev, sizeof(*priv), chan);
-	if (!kcs_bmc)
+	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
 		return -ENOMEM;
 
-	priv = kcs_bmc_priv(kcs_bmc);
 	priv->map = syscon_node_to_regmap(dev->parent->of_node);
 	if (IS_ERR(priv->map)) {
 		dev_err(dev, "Couldn't get regmap\n");
@@ -167,6 +173,9 @@ static int npcm7xx_kcs_probe(struct platform_device *pdev)
 	}
 	priv->reg = &npcm7xx_kcs_reg_tbl[chan - 1];
 
+	kcs_bmc = &priv->kcs_bmc;
+	kcs_bmc->dev = &pdev->dev;
+	kcs_bmc->channel = chan;
 	kcs_bmc->ioreg.idr = priv->reg->dib;
 	kcs_bmc->ioreg.odr = priv->reg->dob;
 	kcs_bmc->ioreg.str = priv->reg->sts;
@@ -174,31 +183,27 @@ static int npcm7xx_kcs_probe(struct platform_device *pdev)
 	kcs_bmc->io_outputb = npcm7xx_kcs_outb;
 	kcs_bmc->io_updateb = npcm7xx_kcs_updateb;
 
-	dev_set_drvdata(dev, kcs_bmc);
+	platform_set_drvdata(pdev, priv);
 
 	npcm7xx_kcs_enable_channel(kcs_bmc, true);
 	rc = npcm7xx_kcs_config_irq(kcs_bmc, pdev);
 	if (rc)
 		return rc;
 
-	rc = misc_register(&kcs_bmc->miscdev);
-	if (rc) {
-		dev_err(dev, "Unable to register device\n");
-		return rc;
-	}
 
 	pr_info("channel=%u idr=0x%x odr=0x%x str=0x%x\n",
 		chan,
 		kcs_bmc->ioreg.idr, kcs_bmc->ioreg.odr, kcs_bmc->ioreg.str);
 
-	return 0;
+	return kcs_bmc_add_device(kcs_bmc);
 }
 
 static int npcm7xx_kcs_remove(struct platform_device *pdev)
 {
-	struct kcs_bmc *kcs_bmc = dev_get_drvdata(&pdev->dev);
+	struct npcm7xx_kcs_bmc *priv = platform_get_drvdata(pdev);
+	struct kcs_bmc *kcs_bmc = &priv->kcs_bmc;
 
-	misc_deregister(&kcs_bmc->miscdev);
+	kcs_bmc_remove_device(kcs_bmc);
 
 	return 0;
 }
-- 
2.27.0