can: mcp251xfd: add dev coredump support

For easier debugging this patch adds dev coredump support to the
driver. A dev coredump is generated in case the chip fails to start or
an error in the interrupt handler is detected.

The dev coredump consists of all chip registers and chip memory, as
well as the driver's internal state of the TEF-, RX- and TX-FIFOs, it
can be analyzed with the mcp251xfd-dump tool of the can-utils:

https://github.com/linux-can/can-utils/tree/master/mcp251xfd
Link: https://lore.kernel.org/r/20210304160328.2752293-2-mkl@pengutronix.de
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

drivers/net/can/spi/mcp251xfd/Kconfig

@@ -3,6 +3,7 @@
 config CAN_MCP251XFD
 	tristate "Microchip MCP251xFD SPI CAN controllers"
 	select REGMAP
+	select WANT_DEV_COREDUMP
 	help
 	  Driver for the Microchip MCP251XFD SPI FD-CAN controller
 	  family.

drivers/net/can/spi/mcp251xfd/Makefile

@@ -6,3 +6,5 @@ mcp251xfd-objs :=
 mcp251xfd-objs += mcp251xfd-core.o
 mcp251xfd-objs += mcp251xfd-crc16.o
 mcp251xfd-objs += mcp251xfd-regmap.o
+
+mcp251xfd-$(CONFIG_DEV_COREDUMP) += mcp251xfd-dump.o

drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c

@@ -1097,6 +1097,7 @@ static int mcp251xfd_chip_start(struct mcp251xfd_priv *priv)
 	return 0;
 
  out_chip_stop:
+	mcp251xfd_dump(priv);
 	mcp251xfd_chip_stop(priv, CAN_STATE_STOPPED);
 
 	return err;
@@ -2277,6 +2278,7 @@ static irqreturn_t mcp251xfd_irq(int irq, void *dev_id)
  out_fail:
 	netdev_err(priv->ndev, "IRQ handler returned %d (intf=0x%08x).\n",
 		   err, priv->regs_status.intf);
+	mcp251xfd_dump(priv);
 	mcp251xfd_chip_interrupts_disable(priv);
 
 	return handled;

drivers/net/can/spi/mcp251xfd/mcp251xfd-dump.c

@@ -0,0 +1,285 @@
+// SPDX-License-Identifier: GPL-2.0
+//
+// mcp251xfd - Microchip MCP251xFD Family CAN controller driver
+//
+// Copyright (c) 2020, 2021 Pengutronix,
+//               Marc Kleine-Budde <kernel@pengutronix.de>
+// Copyright (C) 2015-2018 Etnaviv Project
+//
+
+#include <linux/devcoredump.h>
+
+#include "mcp251xfd.h"
+#include "mcp251xfd-dump.h"
+
+struct mcp251xfd_dump_iter {
+	void *start;
+	struct mcp251xfd_dump_object_header *hdr;
+	void *data;
+};
+
+struct mcp251xfd_dump_reg_space {
+	u16 base;
+	u16 size;
+};
+
+struct mcp251xfd_dump_ring {
+	enum mcp251xfd_dump_object_ring_key key;
+	u32 val;
+};
+
+static const struct mcp251xfd_dump_reg_space mcp251xfd_dump_reg_space[] = {
+	{
+		.base = MCP251XFD_REG_CON,
+		.size = MCP251XFD_REG_FLTOBJ(32) - MCP251XFD_REG_CON,
+	}, {
+		.base = MCP251XFD_RAM_START,
+		.size = MCP251XFD_RAM_SIZE,
+	}, {
+		.base = MCP251XFD_REG_OSC,
+		.size = MCP251XFD_REG_DEVID - MCP251XFD_REG_OSC,
+	},
+};
+
+static void mcp251xfd_dump_header(struct mcp251xfd_dump_iter *iter,
+				  enum mcp251xfd_dump_object_type object_type,
+				  const void *data_end)
+{
+	struct mcp251xfd_dump_object_header *hdr = iter->hdr;
+	unsigned int len;
+
+	len = data_end - iter->data;
+	if (!len)
+		return;
+
+	hdr->magic = cpu_to_le32(MCP251XFD_DUMP_MAGIC);
+	hdr->type = cpu_to_le32(object_type);
+	hdr->offset = cpu_to_le32(iter->data - iter->start);
+	hdr->len = cpu_to_le32(len);
+
+	iter->hdr++;
+	iter->data += len;
+}
+
+static void mcp251xfd_dump_registers(const struct mcp251xfd_priv *priv,
+				     struct mcp251xfd_dump_iter *iter)
+{
+	const int val_bytes = regmap_get_val_bytes(priv->map_rx);
+	struct mcp251xfd_dump_object_reg *reg = iter->data;
+	unsigned int i, j;
+	int err;
+
+	for (i = 0; i < ARRAY_SIZE(mcp251xfd_dump_reg_space); i++) {
+		const struct mcp251xfd_dump_reg_space *reg_space;
+		void *buf;
+
+		reg_space = &mcp251xfd_dump_reg_space[i];
+
+		buf = kmalloc(reg_space->size, GFP_KERNEL);
+		if (!buf)
+			goto out;
+
+		err = regmap_bulk_read(priv->map_reg, reg_space->base,
+				       buf, reg_space->size / val_bytes);
+		if (err) {
+			kfree(buf);
+			continue;
+		}
+
+		for (j = 0; j < reg_space->size; j += sizeof(u32), reg++) {
+			reg->reg = cpu_to_le32(reg_space->base + j);
+			reg->val = cpu_to_le32p(buf + j);
+		}
+
+		kfree(buf);
+	}
+
+ out:
+	mcp251xfd_dump_header(iter, MCP251XFD_DUMP_OBJECT_TYPE_REG, reg);
+}
+
+static void mcp251xfd_dump_ring(struct mcp251xfd_dump_iter *iter,
+				enum mcp251xfd_dump_object_type object_type,
+				const struct mcp251xfd_dump_ring *dump_ring,
+				unsigned int len)
+{
+	struct mcp251xfd_dump_object_reg *reg = iter->data;
+	unsigned int i;
+
+	for (i = 0; i < len; i++, reg++) {
+		reg->reg = cpu_to_le32(dump_ring[i].key);
+		reg->val = cpu_to_le32(dump_ring[i].val);
+	}
+
+	mcp251xfd_dump_header(iter, object_type, reg);
+}
+
+static void mcp251xfd_dump_tef_ring(const struct mcp251xfd_priv *priv,
+				    struct mcp251xfd_dump_iter *iter)
+{
+	const struct mcp251xfd_tef_ring *tef = priv->tef;
+	const struct mcp251xfd_tx_ring *tx = priv->tx;
+	const struct mcp251xfd_dump_ring dump_ring[] = {
+		{
+			.key = MCP251XFD_DUMP_OBJECT_RING_KEY_HEAD,
+			.val = tef->head,
+		}, {
+			.key = MCP251XFD_DUMP_OBJECT_RING_KEY_TAIL,
+			.val = tef->tail,
+		}, {
+			.key = MCP251XFD_DUMP_OBJECT_RING_KEY_BASE,
+			.val = 0,
+		}, {
+			.key = MCP251XFD_DUMP_OBJECT_RING_KEY_NR,
+			.val = 0,
+		}, {
+			.key = MCP251XFD_DUMP_OBJECT_RING_KEY_FIFO_NR,
+			.val = 0,
+		}, {
+			.key = MCP251XFD_DUMP_OBJECT_RING_KEY_OBJ_NUM,
+			.val = tx->obj_num,
+		}, {
+			.key = MCP251XFD_DUMP_OBJECT_RING_KEY_OBJ_SIZE,
+			.val = sizeof(struct mcp251xfd_hw_tef_obj),
+		},
+	};
+
+	mcp251xfd_dump_ring(iter, MCP251XFD_DUMP_OBJECT_TYPE_TEF,
+			    dump_ring, ARRAY_SIZE(dump_ring));
+}
+
+static void mcp251xfd_dump_rx_ring_one(const struct mcp251xfd_priv *priv,
+				       struct mcp251xfd_dump_iter *iter,
+				       const struct mcp251xfd_rx_ring *rx)
+{
+	const struct mcp251xfd_dump_ring dump_ring[] = {
+		{
+			.key = MCP251XFD_DUMP_OBJECT_RING_KEY_HEAD,
+			.val = rx->head,
+		}, {
+			.key = MCP251XFD_DUMP_OBJECT_RING_KEY_TAIL,
+			.val = rx->tail,
+		}, {
+			.key = MCP251XFD_DUMP_OBJECT_RING_KEY_BASE,
+			.val = rx->base,
+		}, {
+			.key = MCP251XFD_DUMP_OBJECT_RING_KEY_NR,
+			.val = rx->nr,
+		}, {
+			.key = MCP251XFD_DUMP_OBJECT_RING_KEY_FIFO_NR,
+			.val = rx->fifo_nr,
+		}, {
+			.key = MCP251XFD_DUMP_OBJECT_RING_KEY_OBJ_NUM,
+			.val = rx->obj_num,
+		}, {
+			.key = MCP251XFD_DUMP_OBJECT_RING_KEY_OBJ_SIZE,
+			.val = rx->obj_size,
+		},
+	};
+
+	mcp251xfd_dump_ring(iter, MCP251XFD_DUMP_OBJECT_TYPE_RX,
+			    dump_ring, ARRAY_SIZE(dump_ring));
+}
+
+static void mcp251xfd_dump_rx_ring(const struct mcp251xfd_priv *priv,
+				   struct mcp251xfd_dump_iter *iter)
+{
+	struct mcp251xfd_rx_ring *rx_ring;
+	unsigned int i;
+
+	mcp251xfd_for_each_rx_ring(priv, rx_ring, i)
+		mcp251xfd_dump_rx_ring_one(priv, iter, rx_ring);
+}
+
+static void mcp251xfd_dump_tx_ring(const struct mcp251xfd_priv *priv,
+				   struct mcp251xfd_dump_iter *iter)
+{
+	const struct mcp251xfd_tx_ring *tx = priv->tx;
+	const struct mcp251xfd_dump_ring dump_ring[] = {
+		{
+			.key = MCP251XFD_DUMP_OBJECT_RING_KEY_HEAD,
+			.val = tx->head,
+		}, {
+			.key = MCP251XFD_DUMP_OBJECT_RING_KEY_TAIL,
+			.val = tx->tail,
+		}, {
+			.key = MCP251XFD_DUMP_OBJECT_RING_KEY_BASE,
+			.val = tx->base,
+		}, {
+			.key = MCP251XFD_DUMP_OBJECT_RING_KEY_NR,
+			.val = 0,
+		}, {
+			.key = MCP251XFD_DUMP_OBJECT_RING_KEY_FIFO_NR,
+			.val = MCP251XFD_TX_FIFO,
+		}, {
+			.key = MCP251XFD_DUMP_OBJECT_RING_KEY_OBJ_NUM,
+			.val = tx->obj_num,
+		}, {
+			.key = MCP251XFD_DUMP_OBJECT_RING_KEY_OBJ_SIZE,
+			.val = tx->obj_size,
+		},
+	};
+
+	mcp251xfd_dump_ring(iter, MCP251XFD_DUMP_OBJECT_TYPE_TX,
+			    dump_ring, ARRAY_SIZE(dump_ring));
+}
+
+static void mcp251xfd_dump_end(const struct mcp251xfd_priv *priv,
+			       struct mcp251xfd_dump_iter *iter)
+{
+	struct mcp251xfd_dump_object_header *hdr = iter->hdr;
+
+	hdr->magic = cpu_to_le32(MCP251XFD_DUMP_MAGIC);
+	hdr->type = cpu_to_le32(MCP251XFD_DUMP_OBJECT_TYPE_END);
+	hdr->offset = cpu_to_le32(0);
+	hdr->len = cpu_to_le32(0);
+
+	/* provoke NULL pointer access, if used after END object */
+	iter->hdr = NULL;
+}
+
+void mcp251xfd_dump(const struct mcp251xfd_priv *priv)
+{
+	struct mcp251xfd_dump_iter iter;
+	unsigned int rings_num, obj_num;
+	unsigned int file_size = 0;
+	unsigned int i;
+
+	/* register space + end marker */
+	obj_num = 2;
+
+	/* register space */
+	for (i = 0; i < ARRAY_SIZE(mcp251xfd_dump_reg_space); i++)
+		file_size += mcp251xfd_dump_reg_space[i].size / sizeof(u32) *
+			sizeof(struct mcp251xfd_dump_object_reg);
+
+	/* TEF ring, RX ring, TX rings */
+	rings_num = 1 + priv->rx_ring_num + 1;
+	obj_num += rings_num;
+	file_size += rings_num * __MCP251XFD_DUMP_OBJECT_RING_KEY_MAX  *
+		sizeof(struct mcp251xfd_dump_object_reg);
+
+	/* size of the headers */
+	file_size += sizeof(*iter.hdr) * obj_num;
+
+	/* allocate the file in vmalloc memory, it's likely to be big */
+	iter.start = __vmalloc(file_size, GFP_KERNEL | __GFP_NOWARN |
+			       __GFP_ZERO | __GFP_NORETRY);
+	if (!iter.start) {
+		netdev_warn(priv->ndev, "Failed to allocate devcoredump file.\n");
+		return;
+	}
+
+	/* point the data member after the headers */
+	iter.hdr = iter.start;
+	iter.data = &iter.hdr[obj_num];
+
+	mcp251xfd_dump_registers(priv, &iter);
+	mcp251xfd_dump_tef_ring(priv, &iter);
+	mcp251xfd_dump_rx_ring(priv, &iter);
+	mcp251xfd_dump_tx_ring(priv, &iter);
+	mcp251xfd_dump_end(priv, &iter);
+
+	dev_coredumpv(&priv->spi->dev, iter.start,
+		      iter.data - iter.start, GFP_KERNEL);
+}

drivers/net/can/spi/mcp251xfd/mcp251xfd-dump.h

@@ -0,0 +1,45 @@
+/* SPDX-License-Identifier: GPL-2.0
+ *
+ * mcp251xfd - Microchip MCP251xFD Family CAN controller driver
+ *
+ * Copyright (c) 2019, 2020, 2021 Pengutronix,
+ *               Marc Kleine-Budde <kernel@pengutronix.de>
+ */
+
+#ifndef _MCP251XFD_DUMP_H
+#define _MCP251XFD_DUMP_H
+
+#define MCP251XFD_DUMP_MAGIC 0x1825434d
+
+enum mcp251xfd_dump_object_type {
+	MCP251XFD_DUMP_OBJECT_TYPE_REG,
+	MCP251XFD_DUMP_OBJECT_TYPE_TEF,
+	MCP251XFD_DUMP_OBJECT_TYPE_RX,
+	MCP251XFD_DUMP_OBJECT_TYPE_TX,
+	MCP251XFD_DUMP_OBJECT_TYPE_END = -1,
+};
+
+enum mcp251xfd_dump_object_ring_key {
+	MCP251XFD_DUMP_OBJECT_RING_KEY_HEAD,
+	MCP251XFD_DUMP_OBJECT_RING_KEY_TAIL,
+	MCP251XFD_DUMP_OBJECT_RING_KEY_BASE,
+	MCP251XFD_DUMP_OBJECT_RING_KEY_NR,
+	MCP251XFD_DUMP_OBJECT_RING_KEY_FIFO_NR,
+	MCP251XFD_DUMP_OBJECT_RING_KEY_OBJ_NUM,
+	MCP251XFD_DUMP_OBJECT_RING_KEY_OBJ_SIZE,
+	__MCP251XFD_DUMP_OBJECT_RING_KEY_MAX,
+};
+
+struct mcp251xfd_dump_object_header {
+	__le32 magic;
+	__le32 type;
+	__le32 offset;
+	__le32 len;
+};
+
+struct mcp251xfd_dump_object_reg {
+	__le32 reg;
+	__le32 val;
+};
+
+#endif

drivers/net/can/spi/mcp251xfd/mcp251xfd.h

@@ -838,4 +838,12 @@ u16 mcp251xfd_crc16_compute2(const void *cmd, size_t cmd_size,
 			     const void *data, size_t data_size);
 u16 mcp251xfd_crc16_compute(const void *data, size_t data_size);
 
+#if IS_ENABLED(CONFIG_DEV_COREDUMP)
+void mcp251xfd_dump(const struct mcp251xfd_priv *priv);
+#else
+static inline void mcp251xfd_dump(const struct mcp251xfd_priv *priv)
+{
+}
+#endif
+
 #endif