ipmi: kcs_bmc: Allow clients to control KCS IRQ state

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.

Cc: CS20 KWLiu <KWLIU@nuvoton.com>
Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
Reviewed-by: Zev Weiss <zweiss@equinix.com>
Message-Id: <20210608104757.582199-10-andrew@aj.id.au>
Signed-off-by: Corey Minyard <cminyard@mvista.com>

1 files changed, 97 insertions, 53 deletions

diff --git a/drivers/char/ipmi/kcs_bmc_aspeed.c b/drivers/char/ipmi/kcs_bmc_aspeed.c
index 08d4290464d8..5bf8d013e4ae 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,
@@ -375,6 +404,10 @@ 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);
@@ -383,6 +416,8 @@ 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);
 
 	rc = kcs_bmc_add_device(&priv->kcs_bmc);
@@ -403,6 +438,15 @@ 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;
 }