Re: [PATCH v3 14/16] ipmi: kcs_bmc_aspeed: Implement KCS SerIRQ configuration

[Zev Weiss <zweiss@equinix.com>]

On Mon, May 10, 2021 at 12:42:11AM CDT, Andrew Jeffery wrote:
>Apply the SerIRQ ID and level/sense behaviours from the devicetree if
>provided.
>
>Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
>---
> drivers/char/ipmi/kcs_bmc_aspeed.c | 182 ++++++++++++++++++++++++++++-
> 1 file changed, 180 insertions(+), 2 deletions(-)
>
>diff --git a/drivers/char/ipmi/kcs_bmc_aspeed.c b/drivers/char/ipmi/kcs_bmc_aspeed.c
>index 8a0b1e18e945..9b81806b4dcb 100644
>--- a/drivers/char/ipmi/kcs_bmc_aspeed.c
>+++ b/drivers/char/ipmi/kcs_bmc_aspeed.c
>@@ -9,6 +9,7 @@
> #include <linux/errno.h>
> #include <linux/interrupt.h>
> #include <linux/io.h>
>+#include <linux/irq.h>
> #include <linux/mfd/syscon.h>
> #include <linux/module.h>
> #include <linux/of.h>
>@@ -28,6 +29,22 @@
>
> #define KCS_CHANNEL_MAX     4
>
>+/*
>+ * Field class descriptions
>+ *
>+ * LPCyE	Enable LPC channel y
>+ * IBFIEy	Input Buffer Full IRQ Enable for LPC channel y
>+ * IRQxEy	Assert SerIRQ x for LPC channel y (Deprecated, use IDyIRQX, IRQXEy)
>+ * IDyIRQX	Use the specified 4-bit SerIRQ for LPC channel y
>+ * SELyIRQX	SerIRQ polarity for LPC channel y (low: 0, high: 1)
>+ * IRQXEy	Assert the SerIRQ specified in IDyIRQX for LPC channel y
>+ */
>+
>+#define LPC_TYIRQX_LOW       0b00
>+#define LPC_TYIRQX_HIGH      0b01
>+#define LPC_TYIRQX_RSVD      0b10
>+#define LPC_TYIRQX_RISING    0b11
>+
> #define LPC_HICR0            0x000
> #define     LPC_HICR0_LPC3E          BIT(7)
> #define     LPC_HICR0_LPC2E          BIT(6)
>@@ -39,6 +56,19 @@
> #define LPC_HICR4            0x010
> #define     LPC_HICR4_LADR12AS       BIT(7)
> #define     LPC_HICR4_KCSENBL        BIT(2)
>+#define LPC_SIRQCR0	     0x070
>+/* IRQ{12,1}E1 are deprecated as of AST2600 A3 but necessary for prior chips */
>+#define     LPC_SIRQCR0_IRQ12E1	     BIT(1)
>+#define     LPC_SIRQCR0_IRQ1E1	     BIT(0)
>+#define LPC_HICR5	     0x080
>+#define     LPC_HICR5_ID3IRQX_MASK   GENMASK(23, 20)
>+#define     LPC_HICR5_ID3IRQX_SHIFT  20
>+#define     LPC_HICR5_ID2IRQX_MASK   GENMASK(19, 16)
>+#define     LPC_HICR5_ID2IRQX_SHIFT  16
>+#define     LPC_HICR5_SEL3IRQX       BIT(15)
>+#define     LPC_HICR5_IRQXE3         BIT(14)
>+#define     LPC_HICR5_SEL2IRQX       BIT(13)
>+#define     LPC_HICR5_IRQXE2         BIT(12)
> #define LPC_LADR3H           0x014
> #define LPC_LADR3L           0x018
> #define LPC_LADR12H          0x01C
>@@ -55,6 +85,13 @@
> #define LPC_HICRB            0x100
> #define     LPC_HICRB_IBFIF4         BIT(1)
> #define     LPC_HICRB_LPC4E          BIT(0)
>+#define LPC_HICRC            0x104
>+#define     LPC_HICRC_ID4IRQX_MASK   GENMASK(7, 4)
>+#define     LPC_HICRC_ID4IRQX_SHIFT  4
>+#define     LPC_HICRC_TY4IRQX_MASK   GENMASK(3, 2)
>+#define     LPC_HICRC_TY4IRQX_SHIFT  2
>+#define     LPC_HICRC_OBF4_AUTO_CLR  BIT(1)
>+#define     LPC_HICRC_IRQXE4         BIT(0)
> #define LPC_LADR4            0x110
> #define LPC_IDR4             0x114
> #define LPC_ODR4             0x118
>@@ -62,11 +99,21 @@
>
> #define OBE_POLL_PERIOD	     (HZ / 2)
>
>+enum aspeed_kcs_irq_mode {
>+	aspeed_kcs_irq_none,
>+	aspeed_kcs_irq_serirq,
>+};
>+
> struct aspeed_kcs_bmc {
> 	struct kcs_bmc_device kcs_bmc;
>
> 	struct regmap *map;
>
>+	struct {
>+		enum aspeed_kcs_irq_mode mode;
>+		int id;
>+	} upstream_irq;
>+
> 	struct {
> 		spinlock_t lock;
> 		bool remove;
>@@ -103,6 +150,49 @@ static void aspeed_kcs_outb(struct kcs_bmc_device *kcs_bmc, u32 reg, u8 data)
>
> 	rc = regmap_write(priv->map, reg, data);
> 	WARN(rc != 0, "regmap_write() failed: %d\n", rc);
>+
>+	/* Trigger the upstream IRQ on ODR writes, if enabled */
>+
>+	switch (reg) {
>+	case LPC_ODR1:
>+	case LPC_ODR2:
>+	case LPC_ODR3:
>+	case LPC_ODR4:
>+		break;
>+	default:
>+		return;
>+	}
>+
>+	if (priv->upstream_irq.mode != aspeed_kcs_irq_serirq)
>+		return;
>+
>+	switch (kcs_bmc->channel) {
>+	case 1:
>+		switch (priv->upstream_irq.id) {
>+		case 12:
>+			regmap_update_bits(priv->map, LPC_SIRQCR0, LPC_SIRQCR0_IRQ12E1,
>+					   LPC_SIRQCR0_IRQ12E1);
>+			break;
>+		case 1:
>+			regmap_update_bits(priv->map, LPC_SIRQCR0, LPC_SIRQCR0_IRQ1E1,
>+					   LPC_SIRQCR0_IRQ1E1);
>+			break;
>+		default:
>+			break;
>+		}
>+		break;
>+	case 2:
>+		regmap_update_bits(priv->map, LPC_HICR5, LPC_HICR5_IRQXE2, LPC_HICR5_IRQXE2);
>+		break;
>+	case 3:
>+		regmap_update_bits(priv->map, LPC_HICR5, LPC_HICR5_IRQXE3, LPC_HICR5_IRQXE3);
>+		break;
>+	case 4:
>+		regmap_update_bits(priv->map, LPC_HICRC, LPC_HICRC_IRQXE4, LPC_HICRC_IRQXE4);
>+		break;
>+	default:
>+		break;
>+	}
> }
>
> static void aspeed_kcs_updateb(struct kcs_bmc_device *kcs_bmc, u32 reg, u8 mask, u8 val)
>@@ -161,6 +251,73 @@ static void aspeed_kcs_set_address(struct kcs_bmc_device *kcs_bmc, u16 addr)
> 	}
> }
>
>+static inline int aspeed_kcs_map_serirq_type(u32 dt_type)
>+{
>+	switch (dt_type) {
>+	case IRQ_TYPE_EDGE_RISING:
>+		return LPC_TYIRQX_RISING;
>+	case IRQ_TYPE_LEVEL_HIGH:
>+		return LPC_TYIRQX_HIGH;
>+	case IRQ_TYPE_LEVEL_LOW:
>+		return LPC_TYIRQX_LOW;
>+	default:
>+		return -EINVAL;
>+	}
>+}
>+
>+static int aspeed_kcs_config_upstream_irq(struct aspeed_kcs_bmc *priv, u32 id, u32 dt_type)
>+{
>+	unsigned int mask, val, hw_type;
>+
>+	if (id > 15)
>+		return -EINVAL;
>+
>+	hw_type = aspeed_kcs_map_serirq_type(dt_type);
>+	if (hw_type < 0)
>+		return hw_type;
>+
>+	priv->upstream_irq.mode = aspeed_kcs_irq_serirq;
>+	priv->upstream_irq.id = id;
>+
>+	switch (priv->kcs_bmc.channel) {
>+	case 1:
>+		/* Needs IRQxE1 rather than (ID1IRQX, SEL1IRQX, IRQXE1) before AST2600 A3 */

I'm struggling a bit with understanding this comment, and relating it to
the code -- it sounds like "we need to do things one way on A3 and
later, and another way on pre-A3", but then...we just break without
doing anything at all either way.  Can you clarify any further?

>+		break;
>+	case 2:
>+		if (!(hw_type == LPC_TYIRQX_LOW || hw_type == LPC_TYIRQX_HIGH))
>+			return -EINVAL;
>+
>+		mask = LPC_HICR5_SEL2IRQX | LPC_HICR5_ID2IRQX_MASK;
>+		val = (id << LPC_HICR5_ID2IRQX_SHIFT);
>+		val |= (hw_type == LPC_TYIRQX_HIGH) ? LPC_HICR5_SEL2IRQX : 0;
>+		regmap_update_bits(priv->map, LPC_HICR5, mask, val);
>+
>+		break;
>+	case 3:
>+		if (!(hw_type == LPC_TYIRQX_LOW || hw_type == LPC_TYIRQX_HIGH))
>+			return -EINVAL;
>+
>+		mask = LPC_HICR5_SEL3IRQX | LPC_HICR5_ID3IRQX_MASK;
>+		val = (id << LPC_HICR5_ID3IRQX_SHIFT);
>+		val |= (hw_type == LPC_TYIRQX_HIGH) ? LPC_HICR5_SEL3IRQX : 0;
>+		regmap_update_bits(priv->map, LPC_HICR5, mask, val);
>+
>+		break;
>+	case 4:
>+		mask = LPC_HICRC_ID4IRQX_MASK | LPC_HICRC_TY4IRQX_MASK | LPC_HICRC_OBF4_AUTO_CLR;
>+		val = (id << LPC_HICRC_ID4IRQX_SHIFT) | (hw_type << LPC_HICRC_TY4IRQX_SHIFT);
>+		regmap_update_bits(priv->map, LPC_HICRC, mask, val);
>+		break;
>+	default:
>+		dev_warn(priv->kcs_bmc.dev,
>+			 "SerIRQ configuration not supported on KCS channel %d\n",
>+			 priv->kcs_bmc.channel);
>+		return -EINVAL;
>+	}
>+
>+	return 0;
>+}
>+
> static void aspeed_kcs_enable_channel(struct kcs_bmc_device *kcs_bmc, bool enable)
> {
> 	struct aspeed_kcs_bmc *priv = to_aspeed_kcs_bmc(kcs_bmc);
>@@ -262,7 +419,7 @@ static irqreturn_t aspeed_kcs_irq(int irq, void *arg)
> 	return kcs_bmc_handle_event(kcs_bmc);
> }
>
>-static int aspeed_kcs_config_irq(struct kcs_bmc_device *kcs_bmc,
>+static int aspeed_kcs_config_downstream_irq(struct kcs_bmc_device *kcs_bmc,
> 			struct platform_device *pdev)
> {
> 	struct device *dev = &pdev->dev;
>@@ -366,6 +523,8 @@ static int aspeed_kcs_probe(struct platform_device *pdev)
> 	struct aspeed_kcs_bmc *priv;
> 	struct device_node *np;
> 	int rc, channel, addr;
>+	bool have_upstream_irq;
>+	u32 upstream_irq[2];
>
> 	np = pdev->dev.of_node->parent;
> 	if (!of_device_is_compatible(np, "aspeed,ast2400-lpc-v2") &&
>@@ -374,6 +533,7 @@ static int aspeed_kcs_probe(struct platform_device *pdev)
> 		dev_err(&pdev->dev, "unsupported LPC device binding\n");
> 		return -ENODEV;
> 	}
>+
> 	ops = of_device_get_match_data(&pdev->dev);
> 	if (!ops)
> 		return -EINVAL;
>@@ -386,6 +546,13 @@ static int aspeed_kcs_probe(struct platform_device *pdev)
> 	if (addr < 0)
> 		return addr;
>
>+	np = pdev->dev.of_node;
>+	rc = of_property_read_u32_array(np, "aspeed,lpc-interrupts", upstream_irq, 2);
>+	if ((rc && rc != -EINVAL))

I think we could probably get by with slightly fewer parens here...

>+		return -EINVAL;
>+
>+	have_upstream_irq = !rc;
>+
> 	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
> 	if (!priv)
> 		return -ENOMEM;
>@@ -408,10 +575,20 @@ static int aspeed_kcs_probe(struct platform_device *pdev)
>
> 	aspeed_kcs_set_address(kcs_bmc, addr);
>
>-	rc = aspeed_kcs_config_irq(kcs_bmc, pdev);
>+	/* Host to BMC IRQ */
>+	rc = aspeed_kcs_config_downstream_irq(kcs_bmc, pdev);
> 	if (rc)
> 		return rc;
>
>+	/* BMC to Host IRQ */
>+	if (have_upstream_irq) {
>+		rc = aspeed_kcs_config_upstream_irq(priv, upstream_irq[0], upstream_irq[1]);
>+		if (rc < 0)
>+			return rc;
>+	} else {
>+		priv->upstream_irq.mode = aspeed_kcs_irq_none;
>+	}
>+
> 	platform_set_drvdata(pdev, priv);
>
> 	aspeed_kcs_irq_mask_update(kcs_bmc, (KCS_BMC_EVENT_TYPE_IBF | KCS_BMC_EVENT_TYPE_OBE), 0);
>@@ -474,4 +651,5 @@ module_platform_driver(ast_kcs_bmc_driver);
>
> MODULE_LICENSE("GPL v2");
> MODULE_AUTHOR("Haiyue Wang <haiyue.wang@linux.intel.com>");
>+MODULE_AUTHOR("Andrew Jeffery <andrew@aj.id.au>");
> MODULE_DESCRIPTION("Aspeed device interface to the KCS BMC device");
>-- 
>2.27.0
>