Subject: Re: [PATCH v3 09/16] ipmi: kcs_bmc: Allow clients to control KCS IRQ state

From: Zev Weiss <[email-masked]>
Date: Fri, 21 May 2021 07:19:28 +0000

On Mon, May 10, 2021 at 12:42:06AM CDT, Andrew Jeffery wrote:
>Add a mechanism for controlling whether the client associated with a
>KCS device will receive Input Buffer Full (IBF) and Output Buffer Empty
>(OBE) events. This enables an abstract implementation of poll() for KCS
>devices.
>
>A wart in the implementation is that the ASPEED KCS devices don't
>support an OBE interrupt for the BMC. Instead we pretend it has one by
>polling the status register waiting for the Output Buffer Full (OBF) bit
>to clear, and generating an event when OBE is observed.
>
>Signed-off-by: Andrew Jeffery <[email-masked]>
>---
> drivers/char/ipmi/kcs_bmc.c         |   6 ++
> drivers/char/ipmi/kcs_bmc.h         |   3 +
> drivers/char/ipmi/kcs_bmc_aspeed.c  | 150 ++++++++++++++++++----------
> drivers/char/ipmi/kcs_bmc_client.h  |   2 +
> drivers/char/ipmi/kcs_bmc_device.h  |   1 +
> drivers/char/ipmi/kcs_bmc_npcm7xx.c |  25 ++++-
> 6 files changed, 130 insertions(+), 57 deletions(-)
>
>diff --git a/drivers/char/ipmi/kcs_bmc.c b/drivers/char/ipmi/kcs_bmc.c
>index 2ec8312ce766..7081541bb6ce 100644
>--- a/drivers/char/ipmi/kcs_bmc.c
>+++ b/drivers/char/ipmi/kcs_bmc.c
>@@ -176,6 +176,12 @@ void kcs_bmc_unregister_driver(struct kcs_bmc_driver *drv)
> }
> EXPORT_SYMBOL(kcs_bmc_unregister_driver);
>
>+void kcs_bmc_update_event_mask(struct kcs_bmc_device *kcs_bmc, u8 mask, u8 events)
>+{
>+	kcs_bmc->ops->irq_mask_update(kcs_bmc, mask, events);
>+}
>+EXPORT_SYMBOL(kcs_bmc_update_event_mask);
>+
> MODULE_LICENSE("GPL v2");
> MODULE_AUTHOR("Haiyue Wang <[email-masked]>");
> MODULE_AUTHOR("Andrew Jeffery <[email-masked]>");
>diff --git a/drivers/char/ipmi/kcs_bmc.h b/drivers/char/ipmi/kcs_bmc.h
>index 3f0cce315b4f..fa408b802c79 100644
>--- a/drivers/char/ipmi/kcs_bmc.h
>+++ b/drivers/char/ipmi/kcs_bmc.h
>@@ -8,6 +8,9 @@
>
> #include <linux/list.h>
>
>+#define KCS_BMC_EVENT_TYPE_OBE	BIT(0)
>+#define KCS_BMC_EVENT_TYPE_IBF	BIT(1)
>+
> #define KCS_BMC_STR_OBF		BIT(0)
> #define KCS_BMC_STR_IBF		BIT(1)
> #define KCS_BMC_STR_CMD_DAT	BIT(3)
>diff --git a/drivers/char/ipmi/kcs_bmc_aspeed.c b/drivers/char/ipmi/kcs_bmc_aspeed.c
>index 8e00675d1019..8b223e58d900 100644
>--- a/drivers/char/ipmi/kcs_bmc_aspeed.c
>+++ b/drivers/char/ipmi/kcs_bmc_aspeed.c
>@@ -60,10 +60,18 @@
> #define LPC_ODR4             0x118
> #define LPC_STR4             0x11C
>
>+#define OBE_POLL_PERIOD	     (HZ / 2)
>+
> struct aspeed_kcs_bmc {
> 	struct kcs_bmc_device kcs_bmc;
>
> 	struct regmap *map;
>+
>+	struct {
>+		spinlock_t lock;
>+		bool remove;
>+		struct timer_list timer;
>+	} obe;
> };
>
> struct aspeed_kcs_of_ops {
>@@ -159,68 +167,89 @@ static void aspeed_kcs_enable_channel(struct kcs_bmc_device *kcs_bmc, bool enabl
>
> 	switch (kcs_bmc->channel) {
> 	case 1:
>-		if (enable) {
>-			regmap_update_bits(priv->map, LPC_HICR2,
>-					LPC_HICR2_IBFIF1, LPC_HICR2_IBFIF1);
>-			regmap_update_bits(priv->map, LPC_HICR0,
>-					LPC_HICR0_LPC1E, LPC_HICR0_LPC1E);
>-		} else {
>-			regmap_update_bits(priv->map, LPC_HICR0,
>-					LPC_HICR0_LPC1E, 0);
>-			regmap_update_bits(priv->map, LPC_HICR2,
>-					LPC_HICR2_IBFIF1, 0);
>-		}
>-		break;
>-
>+		regmap_update_bits(priv->map, LPC_HICR0, LPC_HICR0_LPC1E, enable * LPC_HICR0_LPC1E);
>+		return;
> 	case 2:
>-		if (enable) {
>-			regmap_update_bits(priv->map, LPC_HICR2,
>-					LPC_HICR2_IBFIF2, LPC_HICR2_IBFIF2);
>-			regmap_update_bits(priv->map, LPC_HICR0,
>-					LPC_HICR0_LPC2E, LPC_HICR0_LPC2E);
>-		} else {
>-			regmap_update_bits(priv->map, LPC_HICR0,
>-					LPC_HICR0_LPC2E, 0);
>-			regmap_update_bits(priv->map, LPC_HICR2,
>-					LPC_HICR2_IBFIF2, 0);
>-		}
>-		break;
>-
>+		regmap_update_bits(priv->map, LPC_HICR0, LPC_HICR0_LPC2E, enable * LPC_HICR0_LPC2E);
>+		return;
> 	case 3:
>-		if (enable) {
>-			regmap_update_bits(priv->map, LPC_HICR2,
>-					LPC_HICR2_IBFIF3, LPC_HICR2_IBFIF3);
>-			regmap_update_bits(priv->map, LPC_HICR0,
>-					LPC_HICR0_LPC3E, LPC_HICR0_LPC3E);
>-			regmap_update_bits(priv->map, LPC_HICR4,
>-					LPC_HICR4_KCSENBL, LPC_HICR4_KCSENBL);
>-		} else {
>-			regmap_update_bits(priv->map, LPC_HICR0,
>-					LPC_HICR0_LPC3E, 0);
>-			regmap_update_bits(priv->map, LPC_HICR4,
>-					LPC_HICR4_KCSENBL, 0);
>-			regmap_update_bits(priv->map, LPC_HICR2,
>-					LPC_HICR2_IBFIF3, 0);
>-		}
>-		break;
>-
>+		regmap_update_bits(priv->map, LPC_HICR0, LPC_HICR0_LPC3E, enable * LPC_HICR0_LPC3E);
>+		regmap_update_bits(priv->map, LPC_HICR4,
>+				   LPC_HICR4_KCSENBL, enable * LPC_HICR4_KCSENBL);
>+		return;
> 	case 4:
>-		if (enable)
>-			regmap_update_bits(priv->map, LPC_HICRB,
>-					LPC_HICRB_IBFIF4 | LPC_HICRB_LPC4E,
>-					LPC_HICRB_IBFIF4 | LPC_HICRB_LPC4E);
>+		regmap_update_bits(priv->map, LPC_HICRB, LPC_HICRB_LPC4E, enable * LPC_HICRB_LPC4E);
>+		return;
>+	default:
>+		pr_warn("%s: Unsupported channel: %d", __func__, kcs_bmc->channel);
>+		return;
>+	}
>+}
>+
>+static void aspeed_kcs_check_obe(struct timer_list *timer)
>+{
>+	struct aspeed_kcs_bmc *priv = container_of(timer, struct aspeed_kcs_bmc, obe.timer);
>+	unsigned long flags;
>+	u8 str;
>+
>+	spin_lock_irqsave(&priv->obe.lock, flags);
>+	if (priv->obe.remove) {
>+		spin_unlock_irqrestore(&priv->obe.lock, flags);
>+		return;
>+	}
>+
>+	str = aspeed_kcs_inb(&priv->kcs_bmc, priv->kcs_bmc.ioreg.str);
>+	if (str & KCS_BMC_STR_OBF) {
>+		mod_timer(timer, jiffies + OBE_POLL_PERIOD);
>+		spin_unlock_irqrestore(&priv->obe.lock, flags);
>+		return;
>+	}
>+	spin_unlock_irqrestore(&priv->obe.lock, flags);
>+
>+	kcs_bmc_handle_event(&priv->kcs_bmc);
>+}
>+
>+static void aspeed_kcs_irq_mask_update(struct kcs_bmc_device *kcs_bmc, u8 mask, u8 state)
>+{
>+	struct aspeed_kcs_bmc *priv = to_aspeed_kcs_bmc(kcs_bmc);
>+
>+	/* We don't have an OBE IRQ, emulate it */
>+	if (mask & KCS_BMC_EVENT_TYPE_OBE) {
>+		if (KCS_BMC_EVENT_TYPE_OBE & state)
>+			mod_timer(&priv->obe.timer, jiffies + OBE_POLL_PERIOD);
> 		else
>-			regmap_update_bits(priv->map, LPC_HICRB,
>-					LPC_HICRB_IBFIF4 | LPC_HICRB_LPC4E,
>-					0);
>-		break;
>+			del_timer(&priv->obe.timer);
>+	}
>
>-	default:
>-		break;
>+	if (mask & KCS_BMC_EVENT_TYPE_IBF) {
>+		const bool enable = !!(state & KCS_BMC_EVENT_TYPE_IBF);
>+
>+		switch (kcs_bmc->channel) {
>+		case 1:
>+			regmap_update_bits(priv->map, LPC_HICR2, LPC_HICR2_IBFIF1,
>+					   enable * LPC_HICR2_IBFIF1);
>+			return;
>+		case 2:
>+			regmap_update_bits(priv->map, LPC_HICR2, LPC_HICR2_IBFIF2,
>+					   enable * LPC_HICR2_IBFIF2);
>+			return;
>+		case 3:
>+			regmap_update_bits(priv->map, LPC_HICR2, LPC_HICR2_IBFIF3,
>+					   enable * LPC_HICR2_IBFIF3);
>+			return;
>+		case 4:
>+			regmap_update_bits(priv->map, LPC_HICRB, LPC_HICRB_IBFIF4,
>+					   enable * LPC_HICRB_IBFIF4);
>+			return;
>+		default:
>+			pr_warn("%s: Unsupported channel: %d", __func__, kcs_bmc->channel);
>+			return;
>+		}
> 	}
> }
>
> static const struct kcs_bmc_device_ops aspeed_kcs_ops = {
>+	.irq_mask_update = aspeed_kcs_irq_mask_update,
> 	.io_inputb = aspeed_kcs_inb,
> 	.io_outputb = aspeed_kcs_outb,
> 	.io_updateb = aspeed_kcs_updateb,
>@@ -373,6 +402,10 @@ static int aspeed_kcs_probe(struct platform_device *pdev)
> 		return -ENODEV;
> 	}
>
>+	spin_lock_init(&priv->obe.lock);
>+	priv->obe.remove = false;
>+	timer_setup(&priv->obe.timer, aspeed_kcs_check_obe, 0);
>+
> 	aspeed_kcs_set_address(kcs_bmc, addr);
>
> 	rc = aspeed_kcs_config_irq(kcs_bmc, pdev);
>@@ -381,6 +414,8 @@ static int aspeed_kcs_probe(struct platform_device *pdev)
>
> 	platform_set_drvdata(pdev, priv);
>
>+	aspeed_kcs_irq_mask_update(kcs_bmc, (KCS_BMC_EVENT_TYPE_IBF | KCS_BMC_EVENT_TYPE_OBE),
>+				   KCS_BMC_EVENT_TYPE_IBF);
> 	aspeed_kcs_enable_channel(kcs_bmc, true);
>
> 	kcs_bmc_add_device(&priv->kcs_bmc);
>@@ -397,6 +432,15 @@ static int aspeed_kcs_remove(struct platform_device *pdev)
>
> 	kcs_bmc_remove_device(kcs_bmc);
>
>+	aspeed_kcs_enable_channel(kcs_bmc, false);
>+	aspeed_kcs_irq_mask_update(kcs_bmc, (KCS_BMC_EVENT_TYPE_IBF | KCS_BMC_EVENT_TYPE_OBE), 0);
>+
>+	/* Make sure it's proper dead */
>+	spin_lock_irq(&priv->obe.lock);
>+	priv->obe.remove = true;
>+	spin_unlock_irq(&priv->obe.lock);
>+	del_timer_sync(&priv->obe.timer);
>+
> 	return 0;
> }
>
>diff --git a/drivers/char/ipmi/kcs_bmc_client.h b/drivers/char/ipmi/kcs_bmc_client.h
>index cb38b56cda85..d14e8e0fa230 100644
>--- a/drivers/char/ipmi/kcs_bmc_client.h
>+++ b/drivers/char/ipmi/kcs_bmc_client.h
>@@ -38,6 +38,8 @@ void kcs_bmc_unregister_driver(struct kcs_bmc_driver *drv);
> int kcs_bmc_enable_device(struct kcs_bmc_device *kcs_bmc, struct kcs_bmc_client *client);
> void kcs_bmc_disable_device(struct kcs_bmc_device *kcs_bmc, struct kcs_bmc_client *client);
>
>+void kcs_bmc_update_event_mask(struct kcs_bmc_device *kcs_bmc, u8 mask, u8 events);
>+
> u8 kcs_bmc_read_data(struct kcs_bmc_device *kcs_bmc);
> void kcs_bmc_write_data(struct kcs_bmc_device *kcs_bmc, u8 data);
> u8 kcs_bmc_read_status(struct kcs_bmc_device *kcs_bmc);
>diff --git a/drivers/char/ipmi/kcs_bmc_device.h b/drivers/char/ipmi/kcs_bmc_device.h
>index dd90f8c2ebd6..a1410eb16308 100644
>--- a/drivers/char/ipmi/kcs_bmc_device.h
>+++ b/drivers/char/ipmi/kcs_bmc_device.h
>@@ -9,6 +9,7 @@
> #include "kcs_bmc.h"
>
> struct kcs_bmc_device_ops {
>+	void (*irq_mask_update)(struct kcs_bmc_device *kcs_bmc, u8 mask, u8 enable);
> 	u8 (*io_inputb)(struct kcs_bmc_device *kcs_bmc, u32 reg);
> 	void (*io_outputb)(struct kcs_bmc_device *kcs_bmc, u32 reg, u8 b);
> 	void (*io_updateb)(struct kcs_bmc_device *kcs_bmc, u32 reg, u8 mask, u8 b);
>diff --git a/drivers/char/ipmi/kcs_bmc_npcm7xx.c b/drivers/char/ipmi/kcs_bmc_npcm7xx.c
>index 9f0b168e487c..f8b7162fb830 100644
>--- a/drivers/char/ipmi/kcs_bmc_npcm7xx.c
>+++ b/drivers/char/ipmi/kcs_bmc_npcm7xx.c
>@@ -38,6 +38,7 @@
> #define KCS2CTL		0x2A
> #define KCS3CTL		0x3C
> #define    KCS_CTL_IBFIE	BIT(0)
>+#define    KCS_CTL_OBEIE	BIT(0)
>
> #define KCS1IE		0x1C
> #define KCS2IE		0x2E
>@@ -117,13 +118,23 @@ static void npcm7xx_kcs_enable_channel(struct kcs_bmc_device *kcs_bmc, bool enab
> {
> 	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);
>-
> 	regmap_update_bits(priv->map, priv->reg->ie, KCS_IE_IRQE | KCS_IE_HIRQE,
> 			   enable ? KCS_IE_IRQE | KCS_IE_HIRQE : 0);
> }
>
>+static void npcm7xx_kcs_irq_mask_update(struct kcs_bmc_device *kcs_bmc, u8 mask, u8 state)
>+{
>+	struct npcm7xx_kcs_bmc *priv = to_npcm7xx_kcs_bmc(kcs_bmc);
>+
>+	if (KCS_BMC_EVENT_TYPE_OBE & mask)

Operand ordering still looks a little backwards here...

>+		regmap_update_bits(priv->map, priv->reg->ctl, KCS_CTL_OBEIE,
>+				   !!(KCS_BMC_EVENT_TYPE_OBE & state) * KCS_CTL_OBEIE);

...and here...

>+
>+	if (KCS_BMC_EVENT_TYPE_IBF & mask)

...and here.

Aside from that,

Reviewed-by: Zev Weiss <[email-masked]>

>+		regmap_update_bits(priv->map, priv->reg->ctl, KCS_CTL_IBFIE,
>+				   !!(state & KCS_BMC_EVENT_TYPE_IBF) * KCS_CTL_IBFIE);
>+}
>+
> static irqreturn_t npcm7xx_kcs_irq(int irq, void *arg)
> {
> 	struct kcs_bmc_device *kcs_bmc = arg;
>@@ -146,6 +157,7 @@ static int npcm7xx_kcs_config_irq(struct kcs_bmc_device *kcs_bmc,
> }
>
> static const struct kcs_bmc_device_ops npcm7xx_kcs_ops = {
>+	.irq_mask_update = npcm7xx_kcs_irq_mask_update,
> 	.io_inputb = npcm7xx_kcs_inb,
> 	.io_outputb = npcm7xx_kcs_outb,
> 	.io_updateb = npcm7xx_kcs_updateb,
>@@ -186,11 +198,13 @@ static int npcm7xx_kcs_probe(struct platform_device *pdev)
>
> 	platform_set_drvdata(pdev, priv);
>
>-	npcm7xx_kcs_enable_channel(kcs_bmc, true);
> 	rc = npcm7xx_kcs_config_irq(kcs_bmc, pdev);
> 	if (rc)
> 		return rc;
>
>+	npcm7xx_kcs_irq_mask_update(kcs_bmc, (KCS_BMC_EVENT_TYPE_IBF | KCS_BMC_EVENT_TYPE_OBE),
>+				    KCS_BMC_EVENT_TYPE_IBF);
>+	npcm7xx_kcs_enable_channel(kcs_bmc, true);
>
> 	pr_info("channel=%u idr=0x%x odr=0x%x str=0x%x\n",
> 		chan,
>@@ -208,6 +222,9 @@ static int npcm7xx_kcs_remove(struct platform_device *pdev)
>
> 	kcs_bmc_remove_device(kcs_bmc);
>
>+	npcm7xx_kcs_enable_channel(kcs_bmc, false);
>+	npcm7xx_kcs_irq_mask_update(kcs_bmc, (KCS_BMC_EVENT_TYPE_IBF | KCS_BMC_EVENT_TYPE_OBE), 0);
>+
> 	return 0;
> }
>
>-- 
>2.27.0
>
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