libflash: blocklevel backend for MBOX flash access

The use MBOX protocol to request flash access from the BMC.  Then
read/write to the 'flash' through windows it creates on LPC FW space.

Reference implementation of the mbox flash daemon for BMC userspace:
  https://github.com/cyrilbur-ibm/mboxbridge

Signed-off-by: Cyril Bur <cyril.bur@au1.ibm.com>
Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Stewart Smith <stewart@linux.vnet.ibm.com>

3 files changed, 601 insertions, 1 deletions

diff --git a/libflash/Makefile.inc b/libflash/Makefile.inc
index 4db02a1..ea64eb4 100644
--- a/libflash/Makefile.inc
+++ b/libflash/Makefile.inc
@@ -1,4 +1,4 @@
-LIBFLASH_SRCS = libflash.c libffs.c ecc.c blocklevel.c
+LIBFLASH_SRCS = libflash.c libffs.c ecc.c blocklevel.c mbox-flash.c
 LIBFLASH_OBJS = $(LIBFLASH_SRCS:%.c=%.o)
 
 SUBDIRS += libflash
diff --git a/libflash/mbox-flash.c b/libflash/mbox-flash.c
new file mode 100644
index 0000000..7bf731d
--- /dev/null
+++ b/libflash/mbox-flash.c
@@ -0,0 +1,576 @@
+/* Copyright 2017 IBM Corp.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * 	http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+ * implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#define pr_fmt(fmt) "MBOX-FLASH: " fmt
+
+#define _GNU_SOURCE
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include <skiboot.h>
+#include <timebase.h>
+#include <timer.h>
+#include <libflash/libflash.h>
+#include <libflash/mbox-flash.h>
+#include <lpc.h>
+#include <lpc-mbox.h>
+
+#include <ccan/container_of/container_of.h>
+
+#ifndef __SKIBOOT__
+#error "This libflash backend must be compiled with skiboot"
+#endif
+
+#define MBOX_DEFAULT_TIMEOUT 30
+
+struct lpc_window {
+	uint32_t lpc_addr; /* Offset into LPC space */
+	uint32_t cur_pos;  /* Current position of the window in the flash */
+	uint32_t size;     /* Size of the window into the flash */
+	bool open;
+};
+
+struct mbox_flash_data {
+	uint32_t shift;
+	struct lpc_window read;
+	struct lpc_window write;
+	struct blocklevel_device bl;
+	uint32_t total_size;
+	uint32_t erase_granule;
+	int rc;
+	bool busy;
+	uint8_t seq;
+	struct bmc_mbox_msg msg_mem;
+};
+
+static uint64_t mbox_flash_mask(struct mbox_flash_data *mbox_flash)
+{
+	return (1 << mbox_flash->shift) - 1;
+}
+
+__unused static uint8_t msg_get_u8(struct bmc_mbox_msg *msg, int i)
+{
+	return msg->args[i];
+}
+
+static void msg_put_u8(struct bmc_mbox_msg *msg, int i, uint8_t val)
+{
+	msg->args[i] = val;
+}
+
+static uint16_t msg_get_u16(struct bmc_mbox_msg *msg, int i)
+{
+	return le16_to_cpu(*(uint16_t *)(&msg->args[i]));
+}
+
+static void msg_put_u16(struct bmc_mbox_msg *msg, int i, uint16_t val)
+{
+	uint16_t tmp = cpu_to_le16(val);
+	memcpy(&msg->args[i], &tmp, sizeof(val));
+}
+
+static uint32_t msg_get_u32(struct bmc_mbox_msg *msg, int i)
+{
+	return le32_to_cpu(*(uint32_t *)(&msg->args[i]));
+}
+
+static void msg_put_u32(struct bmc_mbox_msg *msg, int i, uint32_t val)
+{
+	uint32_t tmp = cpu_to_le32(val);
+	memcpy(&msg->args[i], &tmp, sizeof(val));
+}
+
+static struct bmc_mbox_msg *msg_alloc(struct mbox_flash_data *mbox_flash,
+		uint8_t command)
+{
+	/*
+	 * Yes this causes *slow*.
+	 * This file and lpc-mbox have far greater slow points, zeroed
+	 * data regs are VERY useful for debugging. Think twice if this is
+	 * really the performance optimisation you want to make.
+	 */
+	memset(&mbox_flash->msg_mem, 0, sizeof(mbox_flash->msg_mem));
+	mbox_flash->msg_mem.seq = ++mbox_flash->seq;
+	mbox_flash->msg_mem.command = command;
+	return &mbox_flash->msg_mem;
+}
+
+static void msg_free_memory(struct bmc_mbox_msg *mem __unused)
+{
+	/* Allocation is so simple this isn't required */
+}
+
+static int msg_send(struct mbox_flash_data *mbox_flash, struct bmc_mbox_msg *msg)
+{
+	mbox_flash->busy = true;
+	mbox_flash->rc = 0;
+	return bmc_mbox_enqueue(msg);
+}
+
+static int wait_for_bmc(struct mbox_flash_data *mbox_flash, unsigned int timeout_sec)
+{
+	unsigned long last = 1, start = tb_to_secs(mftb());
+	prlog(PR_TRACE, "Waiting for BMC\n");
+	while (mbox_flash->busy && timeout_sec) {
+		long now = tb_to_secs(mftb());
+		if (now - start > last) {
+			timeout_sec--;
+			last = now - start;
+			if (last < timeout_sec / 2)
+				prlog(PR_TRACE, "Been waiting for the BMC for %lu secs\n", last);
+			else
+				prlog(PR_ERR, "BMC NOT RESPONDING %lu second wait\n", last);
+		}
+		/*
+		 * Both functions are important.
+		 * Well time_wait_ms() relaxes the spin... so... its nice
+		 */
+		time_wait_ms(MBOX_DEFAULT_POLL_MS);
+		check_timers(false);
+		asm volatile ("" ::: "memory");
+	}
+
+	if (mbox_flash->busy) {
+		prlog(PR_ERR, "Timeout waiting for BMC\n");
+		mbox_flash->busy = false;
+		return MBOX_R_TIMEOUT;
+	}
+
+	return mbox_flash->rc;
+}
+
+static int lpc_window_read(struct mbox_flash_data *mbox_flash, uint32_t pos,
+			   void *buf, uint32_t len)
+{
+	uint32_t off = mbox_flash->read.lpc_addr + (pos - mbox_flash->read.cur_pos);
+	int rc;
+
+	prlog(PR_TRACE, "Reading at 0x%08x for 0x%08x offset: 0x%08x\n",
+			pos, len, off);
+
+	while(len) {
+		uint32_t chunk;
+		uint32_t dat;
+
+		/* Choose access size */
+		if (len > 3 && !(off & 3)) {
+			rc = lpc_read(OPAL_LPC_FW, off, &dat, 4);
+			if (!rc)
+				*(uint32_t *)buf = dat;
+			chunk = 4;
+		} else {
+			rc = lpc_read(OPAL_LPC_FW, off, &dat, 1);
+			if (!rc)
+				*(uint8_t *)buf = dat;
+			chunk = 1;
+		}
+		if (rc) {
+			prlog(PR_ERR, "lpc_read failure %d to FW 0x%08x\n", rc, off);
+			return rc;
+		}
+		len -= chunk;
+		off += chunk;
+		buf += chunk;
+	}
+
+	return 0;
+}
+
+static int lpc_window_write(struct mbox_flash_data *mbox_flash, uint32_t pos,
+			    const void *buf, uint32_t len)
+{
+	uint32_t off = mbox_flash->write.lpc_addr + (pos - mbox_flash->write.cur_pos);
+	int rc;
+
+
+	prlog(PR_TRACE, "Writing at 0x%08x for 0x%08x offset: 0x%08x\n",
+			pos, len, off);
+
+	while(len) {
+		uint32_t chunk;
+
+		if (len > 3 && !(off & 3)) {
+			rc = lpc_write(OPAL_LPC_FW, off,
+				       *(uint32_t *)buf, 4);
+			chunk = 4;
+		} else {
+			rc = lpc_write(OPAL_LPC_FW, off,
+				       *(uint8_t *)buf, 1);
+			chunk = 1;
+		}
+		if (rc) {
+			prlog(PR_ERR, "lpc_write failure %d to FW 0x%08x\n", rc, off);
+			return rc;
+		}
+		len -= chunk;
+		off += chunk;
+		buf += chunk;
+	}
+
+	return 0;
+}
+
+static int mbox_flash_flush(struct mbox_flash_data *mbox_flash, uint64_t pos,
+		uint64_t len)
+{
+	struct bmc_mbox_msg *msg;
+	int rc;
+
+	msg = msg_alloc(mbox_flash, MBOX_C_WRITE_FLUSH);
+	if (!msg)
+		return FLASH_ERR_MALLOC_FAILED;
+	msg_put_u16(msg, 0, pos >> mbox_flash->shift);
+	msg_put_u32(msg, 2, len);
+
+	rc = msg_send(mbox_flash, msg);
+	if (rc) {
+		prlog(PR_ERR, "Failed to enqueue/send BMC MBOX message\n");
+		goto out;
+	}
+
+	rc = wait_for_bmc(mbox_flash, MBOX_DEFAULT_TIMEOUT);
+	if (rc)
+		prlog(PR_ERR, "Error waiting for BMC\n");
+
+out:
+	msg_free_memory(msg);
+	return rc;
+}
+
+/* Is the current window able perform the complete operation */
+static bool mbox_window_valid(struct lpc_window *win, uint64_t pos,
+			      uint64_t len)
+{
+	if (!win->open)
+		return false;
+	if (pos < win->cur_pos) /* start */
+		return false;
+	if ((pos + len) > (win->cur_pos + win->size)) /* end */
+		return false;
+	return true;
+}
+
+static int mbox_window_move(struct mbox_flash_data *mbox_flash,
+			    struct lpc_window *win, uint8_t command,
+			    uint64_t pos, uint64_t len, uint64_t *size)
+{
+	struct bmc_mbox_msg *msg;
+	int rc;
+
+	/* Is the window currently open valid */
+	if (mbox_window_valid(win, pos, len)) {
+		*size = len;
+		return 0;
+	}
+
+	prlog(PR_DEBUG, "Adjusting the window\n");
+
+	msg = msg_alloc(mbox_flash, command);
+	if (!msg)
+		return FLASH_ERR_MALLOC_FAILED;
+
+	win->cur_pos = pos & ~(mbox_flash_mask(mbox_flash));
+	msg_put_u16(msg, 0, pos >> mbox_flash->shift);
+	rc = msg_send(mbox_flash, msg);
+	if (rc) {
+		prlog(PR_ERR, "Failed to enqueue/send BMC MBOX message\n");
+		goto out;
+	}
+
+	rc = wait_for_bmc(mbox_flash, MBOX_DEFAULT_TIMEOUT);
+	if (rc) {
+		prlog(PR_ERR, "Error waiting for BMC\n");
+		goto out;
+	}
+
+	*size = len;
+	/* Is length past the end of the window? */
+	if ((pos + len) > (win->cur_pos + win->size))
+		/* Adjust size to meet current window */
+		*size =  (win->cur_pos + win->size) - pos;
+
+out:
+	msg_free_memory(msg);
+	return rc;
+}
+
+static int mbox_flash_write(struct blocklevel_device *bl, uint64_t pos,
+			    const void *buf, uint64_t len)
+{
+	struct mbox_flash_data *mbox_flash;
+	uint64_t size;
+
+	int rc = 0;
+
+	/* LPC is only 32bit */
+	if (pos > UINT_MAX || len > UINT_MAX)
+		return FLASH_ERR_PARM_ERROR;
+
+	mbox_flash = container_of(bl, struct mbox_flash_data, bl);
+
+	prlog(PR_TRACE, "Flash write at 0x%08llx for 0x%08llx\n", pos, len);
+	while (len > 0) {
+		/* Move window and get a new size to read */
+		rc = mbox_window_move(mbox_flash, &mbox_flash->write,
+				      MBOX_C_CREATE_WRITE_WINDOW, pos, len,
+				      &size);
+		if (rc)
+			return rc;
+
+ 		/* Perform the read for this window */
+		rc = lpc_window_write(mbox_flash, pos, buf, size);
+		if (rc)
+			return rc;
+
+		/*
+		 * Must flush here as changing the window contents
+		 * without flushing entitles the BMC to throw away the
+		 * data
+		 */
+		rc = mbox_flash_flush(mbox_flash, pos, size);
+		if (rc)
+			return rc;
+
+		len -= size;
+		pos += size;
+		buf += size;
+	}
+	return rc;
+}
+
+static int mbox_flash_read(struct blocklevel_device *bl, uint64_t pos,
+			   void *buf, uint64_t len)
+{
+	struct mbox_flash_data *mbox_flash;
+	uint64_t size;
+
+	int rc = 0;
+
+	/* LPC is only 32bit */
+	if (pos > UINT_MAX || len > UINT_MAX)
+		return FLASH_ERR_PARM_ERROR;
+
+	mbox_flash = container_of(bl, struct mbox_flash_data, bl);
+
+	prlog(PR_TRACE, "Flash read at 0x%08llx for 0x%08llx\n", pos, len);
+	while (len > 0) {
+		/* Move window and get a new size to read */
+		rc = mbox_window_move(mbox_flash, &mbox_flash->read,
+				      MBOX_C_CREATE_READ_WINDOW, pos,
+				      len, &size);
+		if (rc)
+			return rc;
+
+ 		/* Perform the read for this window */
+		rc = lpc_window_read(mbox_flash, pos, buf, size);
+		if (rc)
+			return rc;
+
+		len -= size;
+		pos += size;
+		buf += size;
+	}
+	return rc;
+}
+
+static int mbox_flash_get_info(struct blocklevel_device *bl, const char **name,
+		uint64_t *total_size, uint32_t *erase_granule)
+{
+	struct mbox_flash_data *mbox_flash;
+	struct bmc_mbox_msg *msg;
+	int rc;
+
+	mbox_flash = container_of(bl, struct mbox_flash_data, bl);
+	msg = msg_alloc(mbox_flash, MBOX_C_GET_FLASH_INFO);
+	if (!msg)
+		return FLASH_ERR_MALLOC_FAILED;
+
+	/*
+	 * We want to avoid runtime mallocs in skiboot. The expected
+	 * behavour to uses of libflash is that one can free() the memory
+	 * returned.
+	 * NULL will do for now.
+	 */
+	if (name)
+		*name = NULL;
+
+	mbox_flash->busy = true;
+	rc = msg_send(mbox_flash, msg);
+	if (rc) {
+		prlog(PR_ERR, "Failed to enqueue/send BMC MBOX message\n");
+		goto out;
+	}
+
+	if (wait_for_bmc(mbox_flash, MBOX_DEFAULT_TIMEOUT)) {
+		prlog(PR_ERR, "Error waiting for BMC\n");
+		goto out;
+	}
+
+	mbox_flash->bl.erase_mask = mbox_flash->erase_granule - 1;
+
+	if (total_size)
+		*total_size = mbox_flash->total_size;
+	if (erase_granule)
+		*erase_granule = mbox_flash->erase_granule;
+
+out:
+	msg_free_memory(msg);
+	return rc;
+}
+
+static int mbox_flash_erase(struct blocklevel_device *bl __unused,
+			    uint64_t pos __unused, uint64_t len __unused)
+{
+	/*
+	 * We can probably get away with doing nothing.
+	 * TODO: Rethink this, causes interesting behaviour in pflash.
+	 * Users do expect pflash -{e,E} to do something. This is because
+	 * on real flash this would have set that region to all 0xFF but
+	 * really the erase at the blocklevel interface was only designed
+	 * to be "please make this region writeable".
+	 * It may be wise (despite the large performance penalty) to
+	 * actually write all 0xFF here. I'll leave that as an extersise
+	 * for the future.
+	 */
+	return 0;
+}
+
+static void mbox_flash_callback(struct bmc_mbox_msg *msg, void *priv)
+{
+	struct mbox_flash_data *mbox_flash = priv;
+
+	prlog(PR_TRACE, "%s: BMC OK\n", __func__);
+
+	if (msg->response != MBOX_R_SUCCESS) {
+		prlog(PR_ERR, "Bad response code from BMC %d\n", msg->response);
+		mbox_flash->rc = msg->response;
+		goto out;
+	}
+
+	if (msg->seq != mbox_flash->seq) {
+		/* Uhoh */
+		prlog(PR_ERR, "Sequence numbers don't match! Got: %02x Expected: %02x\n",
+				msg->seq, mbox_flash->seq);
+		mbox_flash->rc = MBOX_R_SYSTEM_ERROR;
+		goto out;
+	}
+
+	mbox_flash->rc = 0;
+
+	switch (msg->command) {
+		case MBOX_C_RESET_STATE:
+			break;
+		case MBOX_C_GET_MBOX_INFO:
+			mbox_flash->read.size = msg_get_u16(msg, 1) << mbox_flash->shift;
+			mbox_flash->write.size = msg_get_u16(msg, 3) << mbox_flash->shift;
+			break;
+		case MBOX_C_GET_FLASH_INFO:
+			mbox_flash->total_size = msg_get_u32(msg, 0);
+			mbox_flash->erase_granule = msg_get_u32(msg, 4);
+			break;
+		case MBOX_C_CREATE_READ_WINDOW:
+			mbox_flash->read.lpc_addr = msg_get_u16(msg, 0) << mbox_flash->shift;
+			mbox_flash->read.open = true;
+			mbox_flash->write.open = false;
+			break;
+		case MBOX_C_CLOSE_WINDOW:
+			break;
+		case MBOX_C_CREATE_WRITE_WINDOW:
+			mbox_flash->write.lpc_addr = msg_get_u16(msg, 0) << mbox_flash->shift;
+			mbox_flash->write.open = true;
+			mbox_flash->read.open = false;
+			break;
+		case MBOX_C_MARK_WRITE_DIRTY:
+			break;
+		case MBOX_C_WRITE_FLUSH:
+			break;
+		case MBOX_C_BMC_EVENT_ACK:
+			break;
+		default:
+			prlog(PR_ERR, "Got response to unknown command %02x\n", msg->command);
+			mbox_flash->rc = -1;
+	}
+
+out:
+	mbox_flash->busy = false;
+}
+
+int mbox_flash_init(struct blocklevel_device **bl)
+{
+	struct mbox_flash_data *mbox_flash;
+	struct bmc_mbox_msg *msg;
+	int rc;
+
+	if (!bl)
+		return FLASH_ERR_PARM_ERROR;
+
+	*bl = NULL;
+
+	mbox_flash = zalloc(sizeof(struct mbox_flash_data));
+	if (!mbox_flash)
+		return FLASH_ERR_MALLOC_FAILED;
+
+	/* For V1 of the protocol this is fixed. This could change */
+	mbox_flash->shift = 12;
+
+	bmc_mbox_register_callback(&mbox_flash_callback, mbox_flash);
+
+	msg = msg_alloc(mbox_flash, MBOX_C_GET_MBOX_INFO);
+	if (!msg) {
+		rc = FLASH_ERR_MALLOC_FAILED;
+		goto out;
+	}
+
+	msg_put_u8(msg, 0, 1); /* V1, do better */
+
+	rc = msg_send(mbox_flash, msg);
+	if (rc) {
+		prlog(PR_ERR, "Failed to enqueue/send BMC MBOX message\n");
+		goto out_msg;
+	}
+
+	rc = wait_for_bmc(mbox_flash, MBOX_DEFAULT_TIMEOUT);
+	if (rc) {
+		prlog(PR_ERR, "Error waiting for BMC\n");
+		goto out_msg;
+	}
+
+	mbox_flash->bl.keep_alive = 0;
+	mbox_flash->bl.read = &mbox_flash_read;
+	mbox_flash->bl.write = &mbox_flash_write;
+	mbox_flash->bl.erase = &mbox_flash_erase;
+	mbox_flash->bl.get_info = &mbox_flash_get_info;
+
+	*bl = &(mbox_flash->bl);
+	return 0;
+
+out_msg:
+	msg_free_memory(msg);
+out:
+	free(mbox_flash);
+	return rc;
+}
+
+void mbox_flash_exit(struct blocklevel_device *bl)
+{
+	struct mbox_flash_data *mbox_flash;
+	if (bl) {
+		mbox_flash = container_of(bl, struct mbox_flash_data, bl);
+		free(mbox_flash);
+	}
+}
diff --git a/libflash/mbox-flash.h b/libflash/mbox-flash.h
new file mode 100644
index 0000000..cd587d4
--- /dev/null
+++ b/libflash/mbox-flash.h
@@ -0,0 +1,24 @@
+/* Copyright 2017 IBM Corp.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * 	http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+ * implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef __LIBFLASH_MBOX_FLASH_H
+#define __LIBFLASH_MBOX_FLASH_H
+
+int mbox_flash_init(struct blocklevel_device **bl);
+void mbox_flash_exit(struct blocklevel_device *bl);
+#endif /* __LIBFLASH_MBOX_FLASH_H */
+
+