wimax/i2400m: rework bootrom initialization to be more flexible

This modifies the bootrom initialization code of the i2400m driver so
it can more easily support upcoming hardware.

Currently, the code detects two types of barkers (magic numbers) sent
by the device to indicate the types of firmware it would take (signed
vs non-signed).

This schema is extended so that multiple reboot barkers are
recognized; upcoming hw will expose more types barkers which will have
to match a header in the firmware image before we can load it.

For that, a barker database is introduced; the first time the device
sends a barker, it is matched in the database. That gives the driver
the information needed to decide how to upload the firmware and which
types of firmware to use. The database can be populated from module
parameters.

The execution flow is not altered; a new function
(i2400m_is_boot_barker) is introduced to determine in the RX path if
the device has sent a boot barker. This function is becoming heavier,
so it is put away from the hot reception path [this is why there is
some reorganization in sdio-rx.c:i2400ms_rx and
usb-notifc.c:i2400mu_notification_grok()].

The documentation on the process has also been updated.

All these modifications are heavily based on previous work by Dirk
Brandewie <dirk.brandewie@intel.com>.

Signed-off-by: Inaky Perez-Gonzalez <inaky@linux.intel.com>

1 files changed, 271 insertions, 42 deletions

diff --git a/drivers/net/wimax/i2400m/fw.c b/drivers/net/wimax/i2400m/fw.c
index c962a8d..798564e 100644
--- a/drivers/net/wimax/i2400m/fw.c
+++ b/drivers/net/wimax/i2400m/fw.c
@@ -40,11 +40,9 @@
  *
  * THE PROCEDURE
  *
- * (this is decribed for USB, but for SDIO is similar)
- *
- * The 2400m works in two modes: boot-mode or normal mode. In boot
- * mode we can execute only a handful of commands targeted at
- * uploading the firmware and launching it.
+ * The 2400m and derived devices work in two modes: boot-mode or
+ * normal mode. In boot mode we can execute only a handful of commands
+ * targeted at uploading the firmware and launching it.
  *
  * The 2400m enters boot mode when it is first connected to the
  * system, when it crashes and when you ask it to reboot. There are
@@ -52,18 +50,26 @@
  * firmwares signed with a certain private key, non-signed takes any
  * firmware. Normal hardware takes only signed firmware.
  *
- * Upon entrance to boot mode, the device sends a few zero length
- * packets (ZLPs) on the notification endpoint, then a reboot barker
- * (4 le32 words with value I2400M_{S,N}BOOT_BARKER). We ack it by
- * sending the same barker on the bulk out endpoint. The device acks
- * with a reboot ack barker (4 le32 words with value 0xfeedbabe) and
- * then the device is fully rebooted. At this point we can upload the
- * firmware.
+ * On boot mode, in USB, we write to the device using the bulk out
+ * endpoint and read from it in the notification endpoint. In SDIO we
+ * talk to it via the write address and read from the read address.
+ *
+ * Upon entrance to boot mode, the device sends (preceeded with a few
+ * zero length packets (ZLPs) on the notification endpoint in USB) a
+ * reboot barker (4 le32 words with the same value). We ack it by
+ * sending the same barker to the device. The device acks with a
+ * reboot ack barker (4 le32 words with value I2400M_ACK_BARKER) and
+ * then is fully booted. At this point we can upload the firmware.
+ *
+ * Note that different iterations of the device and EEPROM
+ * configurations will send different [re]boot barkers; these are
+ * collected in i2400m_barker_db along with the firmware
+ * characteristics they require.
  *
  * This process is accomplished by the i2400m_bootrom_init()
  * function. All the device interaction happens through the
  * i2400m_bm_cmd() [boot mode command]. Special return values will
- * indicate if the device resets.
+ * indicate if the device did reset during the process.
  *
  * After this, we read the MAC address and then (if needed)
  * reinitialize the device. We need to read it ahead of time because
@@ -101,6 +107,11 @@
  *
  * ROADMAP
  *
+ * i2400m_barker_db_init              Called by i2400m_driver_init()
+ *   i2400m_barker_db_add
+ *
+ * i2400m_barker_db_exit              Called by i2400m_driver_exit()
+ *
  * i2400m_dev_bootstrap               Called by __i2400m_dev_start()
  *   request_firmware
  *   i2400m_fw_check
@@ -125,6 +136,7 @@
  *   i2400m->bus_bm_cmd_send()
  *   i2400m->bus_bm_wait_for_ack
  *   __i2400m_bm_ack_verify
+ *     i2400m_is_boot_barker
  *
  * i2400m_bm_cmd_prepare              Used by bus-drivers to prep
  *                                    commands before sending
@@ -175,6 +187,237 @@ EXPORT_SYMBOL_GPL(i2400m_bm_cmd_prepare);
 
 
 /*
+ * Database of known barkers.
+ *
+ * A barker is what the device sends indicating he is ready to be
+ * bootloaded. Different versions of the device will send different
+ * barkers. Depending on the barker, it might mean the device wants
+ * some kind of firmware or the other.
+ */
+static struct i2400m_barker_db {
+	__le32 data[4];
+} *i2400m_barker_db;
+static size_t i2400m_barker_db_used, i2400m_barker_db_size;
+
+
+static
+int i2400m_zrealloc_2x(void **ptr, size_t *_count, size_t el_size,
+		       gfp_t gfp_flags)
+{
+	size_t old_count = *_count,
+		new_count = old_count ? 2 * old_count : 2,
+		old_size = el_size * old_count,
+		new_size = el_size * new_count;
+	void *nptr = krealloc(*ptr, new_size, gfp_flags);
+	if (nptr) {
+		/* zero the other half or the whole thing if old_count
+		 * was zero */
+		if (old_size == 0)
+			memset(nptr, 0, new_size);
+		else
+			memset(nptr + old_size, 0, old_size);
+		*_count = new_count;
+		*ptr = nptr;
+		return 0;
+	} else
+		return -ENOMEM;
+}
+
+
+/*
+ * Add a barker to the database
+ *
+ * This cannot used outside of this module and only at at module_init
+ * time. This is to avoid the need to do locking.
+ */
+static
+int i2400m_barker_db_add(u32 barker_id)
+{
+	int result;
+
+	struct i2400m_barker_db *barker;
+	if (i2400m_barker_db_used >= i2400m_barker_db_size) {
+		result = i2400m_zrealloc_2x(
+			(void **) &i2400m_barker_db, &i2400m_barker_db_size,
+			sizeof(i2400m_barker_db[0]), GFP_KERNEL);
+		if (result < 0)
+			return result;
+	}
+	barker = i2400m_barker_db + i2400m_barker_db_used++;
+	barker->data[0] = le32_to_cpu(barker_id);
+	barker->data[1] = le32_to_cpu(barker_id);
+	barker->data[2] = le32_to_cpu(barker_id);
+	barker->data[3] = le32_to_cpu(barker_id);
+	return 0;
+}
+
+
+void i2400m_barker_db_exit(void)
+{
+	kfree(i2400m_barker_db);
+	i2400m_barker_db = NULL;
+	i2400m_barker_db_size = 0;
+	i2400m_barker_db_used = 0;
+}
+
+
+/*
+ * Helper function to add all the known stable barkers to the barker
+ * database.
+ */
+static
+int i2400m_barker_db_known_barkers(void)
+{
+	int result;
+
+	result = i2400m_barker_db_add(I2400M_NBOOT_BARKER);
+	if (result < 0)
+		goto error_add;
+	result = i2400m_barker_db_add(I2400M_SBOOT_BARKER);
+	if (result < 0)
+		goto error_add;
+error_add:
+       return result;
+}
+
+
+/*
+ * Initialize the barker database
+ *
+ * This can only be used from the module_init function for this
+ * module; this is to avoid the need to do locking.
+ *
+ * @options: command line argument with extra barkers to
+ *     recognize. This is a comma-separated list of 32-bit hex
+ *     numbers. They are appended to the existing list. Setting 0
+ *     cleans the existing list and starts a new one.
+ */
+int i2400m_barker_db_init(const char *_options)
+{
+	int result;
+	char *options = NULL, *options_orig, *token;
+
+	i2400m_barker_db = NULL;
+	i2400m_barker_db_size = 0;
+	i2400m_barker_db_used = 0;
+
+	result = i2400m_barker_db_known_barkers();
+	if (result < 0)
+		goto error_add;
+	/* parse command line options from i2400m.barkers */
+	if (_options != NULL) {
+		unsigned barker;
+
+		options_orig = kstrdup(_options, GFP_KERNEL);
+		if (options_orig == NULL)
+			goto error_parse;
+		options = options_orig;
+
+		while ((token = strsep(&options, ",")) != NULL) {
+			if (*token == '\0')	/* eat joint commas */
+				continue;
+			if (sscanf(token, "%x", &barker) != 1
+			    || barker > 0xffffffff) {
+				printk(KERN_ERR "%s: can't recognize "
+				       "i2400m.barkers value '%s' as "
+				       "a 32-bit number\n",
+				       __func__, token);
+				result = -EINVAL;
+				goto error_parse;
+			}
+			if (barker == 0) {
+				/* clean list and start new */
+				i2400m_barker_db_exit();
+				continue;
+			}
+			result = i2400m_barker_db_add(barker);
+			if (result < 0)
+				goto error_add;
+		}
+		kfree(options_orig);
+	}
+	return 0;
+
+error_parse:
+error_add:
+	kfree(i2400m_barker_db);
+	return result;
+}
+
+
+/*
+ * Recognize a boot barker
+ *
+ * @buf: buffer where the boot barker.
+ * @buf_size: size of the buffer (has to be 16 bytes). It is passed
+ *     here so the function can check it for the caller.
+ *
+ * Note that as a side effect, upon identifying the obtained boot
+ * barker, this function will set i2400m->barker to point to the right
+ * barker database entry. Subsequent calls to the function will result
+ * in verifying that the same type of boot barker is returned when the
+ * device [re]boots (as long as the same device instance is used).
+ *
+ * Return: 0 if @buf matches a known boot barker. -ENOENT if the
+ *     buffer in @buf doesn't match any boot barker in the database or
+ *     -EILSEQ if the buffer doesn't have the right size.
+ */
+int i2400m_is_boot_barker(struct i2400m *i2400m,
+			  const void *buf, size_t buf_size)
+{
+	int result;
+	struct device *dev = i2400m_dev(i2400m);
+	struct i2400m_barker_db *barker;
+	int i;
+
+	result = -ENOENT;
+	if (buf_size != sizeof(i2400m_barker_db[i].data))
+		return result;
+
+	/* Short circuit if we have already discovered the barker
+	 * associated with the device. */
+	if (i2400m->barker
+	    && !memcmp(buf, i2400m->barker, sizeof(i2400m->barker->data))) {
+		unsigned index = (i2400m->barker - i2400m_barker_db)
+			/ sizeof(*i2400m->barker);
+		d_printf(2, dev, "boot barker cache-confirmed #%u/%08x\n",
+			 index, le32_to_cpu(i2400m->barker->data[0]));
+		return 0;
+	}
+
+	for (i = 0; i < i2400m_barker_db_used; i++) {
+		barker = &i2400m_barker_db[i];
+		BUILD_BUG_ON(sizeof(barker->data) != 16);
+		if (memcmp(buf, barker->data, sizeof(barker->data)))
+			continue;
+
+		if (i2400m->barker == NULL) {
+			i2400m->barker = barker;
+			d_printf(1, dev, "boot barker set to #%u/%08x\n",
+				 i, le32_to_cpu(barker->data[0]));
+			if (barker->data[0] == le32_to_cpu(I2400M_NBOOT_BARKER))
+				i2400m->sboot = 0;
+			else
+				i2400m->sboot = 1;
+		} else if (i2400m->barker != barker) {
+			dev_err(dev, "HW inconsistency: device "
+				"reports a different boot barker "
+				"than set (from %08x to %08x)\n",
+				le32_to_cpu(i2400m->barker->data[0]),
+				le32_to_cpu(barker->data[0]));
+			result = -EIO;
+		} else
+			d_printf(2, dev, "boot barker confirmed #%u/%08x\n",
+				 i, le32_to_cpu(barker->data[0]));
+		result = 0;
+		break;
+	}
+	return result;
+}
+EXPORT_SYMBOL_GPL(i2400m_is_boot_barker);
+
+
+/*
  * Verify the ack data received
  *
  * Given a reply to a boot mode command, chew it and verify everything
@@ -204,20 +447,10 @@ ssize_t __i2400m_bm_ack_verify(struct i2400m *i2400m, int opcode,
 			opcode, ack_size, sizeof(*ack));
 		goto error_ack_short;
 	}
-	if (ack_size == sizeof(i2400m_NBOOT_BARKER)
-		 && memcmp(ack, i2400m_NBOOT_BARKER, sizeof(*ack)) == 0) {
-		result = -ERESTARTSYS;
-		i2400m->sboot = 0;
-		d_printf(6, dev, "boot-mode cmd %d: "
-			 "HW non-signed boot barker\n", opcode);
-		goto error_reboot;
-	}
-	if (ack_size == sizeof(i2400m_SBOOT_BARKER)
-		 && memcmp(ack, i2400m_SBOOT_BARKER, sizeof(*ack)) == 0) {
+	result = i2400m_is_boot_barker(i2400m, ack, ack_size);
+	if (result >= 0) {
 		result = -ERESTARTSYS;
-		i2400m->sboot = 1;
-		d_printf(6, dev, "boot-mode cmd %d: HW signed reboot barker\n",
-			 opcode);
+		d_printf(6, dev, "boot-mode cmd %d: HW boot barker\n", opcode);
 		goto error_reboot;
 	}
 	if (ack_size == sizeof(i2400m_ACK_BARKER)
@@ -590,9 +823,6 @@ int i2400m_dnload_finalize(struct i2400m *i2400m,
  *
  *     < 0 errno code on error, 0 if ok.
  *
- *     i2400m->sboot set to 0 for unsecure boot process, 1 for secure
- *     boot process.
- *
  * Description:
  *
  * Tries hard enough to put the device in boot-mode. There are two
@@ -619,7 +849,7 @@ int i2400m_bootrom_init(struct i2400m *i2400m, enum i2400m_bri flags)
 	int count = i2400m->bus_bm_retries;
 	int ack_timeout_cnt = 1;
 
-	BUILD_BUG_ON(sizeof(*cmd) != sizeof(i2400m_NBOOT_BARKER));
+	BUILD_BUG_ON(sizeof(*cmd) != sizeof(i2400m_barker_db[0].data));
 	BUILD_BUG_ON(sizeof(ack) != sizeof(i2400m_ACK_BARKER));
 
 	d_fnstart(4, dev, "(i2400m %p flags 0x%08x)\n", i2400m, flags);
@@ -647,8 +877,14 @@ do_reboot:
 	case -ETIMEDOUT:	/* device has timed out, we might be in boot
 				 * mode already and expecting an ack, let's try
 				 * that */
-		dev_info(dev, "warm reset timed out, trying an ack\n");
-		goto do_reboot_ack;
+		if (i2400m->barker == NULL) {
+			dev_info(dev, "warm reset timed out, unknown barker "
+				 "type, rebooting\n");
+			goto do_reboot;
+		} else {
+			dev_info(dev, "warm reset timed out, trying an ack\n");
+			goto do_reboot_ack;
+		}
 	case -EPROTO:
 	case -ESHUTDOWN:	/* dev is gone */
 	case -EINTR:		/* user cancelled */
@@ -664,12 +900,7 @@ do_reboot:
 	 * notification and report it as -EISCONN. */
 do_reboot_ack:
 	d_printf(4, dev, "device reboot ack: sending ack [%d # left]\n", count);
-	if (i2400m->sboot == 0)
-		memcpy(cmd, i2400m_NBOOT_BARKER,
-		       sizeof(i2400m_NBOOT_BARKER));
-	else
-		memcpy(cmd, i2400m_SBOOT_BARKER,
-		       sizeof(i2400m_SBOOT_BARKER));
+	memcpy(cmd, i2400m->barker->data, sizeof(i2400m->barker->data));
 	result = i2400m_bm_cmd(i2400m, cmd, sizeof(*cmd),
 			       &ack, sizeof(ack), I2400M_BM_CMD_RAW);
 	switch (result) {
@@ -682,10 +913,8 @@ do_reboot_ack:
 		d_printf(4, dev, "reboot ack: got ack barker - good\n");
 		break;
 	case -ETIMEDOUT:	/* no response, maybe it is the other type? */
-		if (ack_timeout_cnt-- >= 0) {
-			d_printf(4, dev, "reboot ack timedout: "
-				 "trying the other type?\n");
-			i2400m->sboot = !i2400m->sboot;
+		if (ack_timeout_cnt-- < 0) {
+			d_printf(4, dev, "reboot ack timedout: retrying\n");
 			goto do_reboot_ack;
 		} else {
 			dev_err(dev, "reboot ack timedout too long: "