Eric Lee / smarc-uboot | Embedian Git Server

Commit 65b60897a700e63af02ba46249de60ed3f79ca41

Authored by Martin Fuzzey 2018-10-23 00:31:08 +0800

Committed by Tom Rini 2018-11-01 22:02:10 +0800

Exists in smarc_8mq_lf_v2020.04 and in 13 other branches

w1: fix data abort if no one wire bus master present

When the "w1 bus" command is used with no bus master present
a data abort may occur.

This is because uclass_first_device() returns zero, but sets the output
struct udevice pointer to NULL in the no device found case.

Fix w1_get_bus() to account for this and return an error code
as is expected by the callers.

Signed-off-by: Martin Fuzzey <martin.fuzzey@flowbird.group>
Reviewed-by: Eugen Hristev <eugen.hristev@microchip.com>

Showing 1 changed file with 8 additions and 6 deletions Inline Diff

drivers/w1/w1-uclass.c

drivers/w1/w1-uclass.c

Diff comments View file @ 65b6089

 // SPDX-License-Identifier:	GPL-2.0+
 /*
  *
  * Copyright (c) 2015 Free Electrons
  * Copyright (c) 2015 NextThing Co.
  * Copyright (c) 2018 Microchip Technology, Inc.
  *
  * Maxime Ripard <maxime.ripard@free-electrons.com>
  * Eugen Hristev <eugen.hristev@microchip.com>
  *
  */
 #include <common.h>
 #include <dm.h>
 #include <w1.h>
 #include <w1-eeprom.h>
 #include <dm/device-internal.h>
 #define W1_MATCH_ROM	0x55
 #define W1_SKIP_ROM	0xcc
 #define W1_SEARCH	0xf0
 struct w1_bus {
 	u64	search_id;
 };
 static int w1_enumerate(struct udevice *bus)
 {
 	const struct w1_ops *ops = device_get_ops(bus);
 	struct w1_bus *w1 = dev_get_uclass_priv(bus);
 	u64 last_rn, rn = w1->search_id, tmp64;
 	bool last_device = false;
 	int search_bit, desc_bit = 64;
 	int last_zero = -1;
 	u8 triplet_ret = 0;
 	int i;
 	if (!ops->reset || !ops->write_byte || !ops->triplet)
 		return -ENOSYS;
 	while (!last_device) {
 		last_rn = rn;
 		rn = 0;
 		/*
 		 * Reset bus and all 1-wire device state machines
 		 * so they can respond to our requests.
 		 *
 		 * Return 0 - device(s) present, 1 - no devices present.
 		 */
 		if (ops->reset(bus)) {
 			debug("%s: No devices present on the wire.\n",
 			      __func__);
 			break;
 		}
 		/* Start the search */
 		ops->write_byte(bus, W1_SEARCH);
 		for (i = 0; i < 64; ++i) {
 			/* Determine the direction/search bit */
 			if (i == desc_bit)
 				/* took the 0 path last time, so take the 1 path */
 				search_bit = 1;
 			else if (i > desc_bit)
 				/* take the 0 path on the next branch */
 				search_bit = 0;
 			else
 				search_bit = ((last_rn >> i) & 0x1);
 			/* Read two bits and write one bit */
 			triplet_ret = ops->triplet(bus, search_bit);
 			/* quit if no device responded */
 			if ((triplet_ret & 0x03) == 0x03)
 				break;
 			/* If both directions were valid, and we took the 0 path... */
 			if (triplet_ret == 0)
 				last_zero = i;
 			/* extract the direction taken & update the device number */
 			tmp64 = (triplet_ret >> 2);
 			rn |= (tmp64 << i);
 		}
 		/* last device or error, aborting here */
 		if ((triplet_ret & 0x03) == 0x03)
 			last_device = true;
 		if ((triplet_ret & 0x03) != 0x03) {
 			if (desc_bit == last_zero || last_zero < 0) {
 				last_device = 1;
 				w1->search_id = 0;
 			} else {
 				w1->search_id = rn;
 			}
 			desc_bit = last_zero;
 			debug("%s: Detected new device 0x%llx (family 0x%x)\n",
 			      bus->name, rn, (u8)(rn & 0xff));
 			/* attempt to register as w1-eeprom device */
 			w1_eeprom_register_new_device(rn);
 		}
 	}
 	return 0;
 }
 int w1_get_bus(int busnum, struct udevice **busp)
 {
 	int ret, i = 0;
 	struct udevice *dev;
 	for (ret = uclass_first_device(UCLASS_W1, &dev);
-	     !ret;
+	     dev && !ret;
-	     uclass_next_device(&dev), i++) {
+	     ret = uclass_next_device(&dev), i++) {
-		if (ret) {
-			debug("Cannot find w1 bus %d\n", busnum);
-			return ret;
-		}
 		if (i == busnum) {
 			*busp = dev;
 			return 0;
 		}
 	}
+	if (!ret) {
+		debug("Cannot find w1 bus %d\n", busnum);
+		ret = -ENODEV;
+	}
 	return ret;
 }
 u8 w1_get_device_family(struct udevice *dev)
 {
 	struct w1_device *w1 = dev_get_parent_platdata(dev);
 	return w1->id & 0xff;
 }
 int w1_reset_select(struct udevice *dev)
 {
 	struct w1_device *w1 = dev_get_parent_platdata(dev);
 	struct udevice *bus = dev_get_parent(dev);
 	const struct w1_ops *ops = device_get_ops(bus);
 	int i;
 	if (!ops->reset || !ops->write_byte)
 		return -ENOSYS;
 	ops->reset(bus);
 	ops->write_byte(bus, W1_MATCH_ROM);
 	for (i = 0; i < sizeof(w1->id); i++)
 		ops->write_byte(bus, (w1->id >> (i * 8)) & 0xff);
 	return 0;
 }
 int w1_read_byte(struct udevice *dev)
 {
 	struct udevice *bus = dev_get_parent(dev);
 	const struct w1_ops *ops = device_get_ops(bus);
 	if (!ops->read_byte)
 		return -ENOSYS;
 	return ops->read_byte(bus);
 }
 int w1_read_buf(struct udevice *dev, u8 *buf, unsigned int count)
 {
 	int i, ret;
 	for (i = 0; i < count; i++) {
 		ret = w1_read_byte(dev);
 		if (ret < 0)
 			return ret;
 		buf[i] = ret & 0xff;
 	}
 	return 0;
 }
 int w1_write_byte(struct udevice *dev, u8 byte)
 {
 	struct udevice *bus = dev_get_parent(dev);
 	const struct w1_ops *ops = device_get_ops(bus);
 	if (!ops->write_byte)
 		return -ENOSYS;
 	ops->write_byte(bus, byte);
 	return 0;
 }
 static int w1_post_probe(struct udevice *bus)
 {
 	w1_enumerate(bus);
 	return 0;
 }
 int w1_init(void)
 {
 	struct udevice *bus;
 	struct uclass *uc;
 	int ret;
 	ret = uclass_get(UCLASS_W1, &uc);
 	if (ret)
 		return ret;
 	uclass_foreach_dev(bus, uc) {
 		ret = device_probe(bus);
 		if (ret == -ENODEV) {	/* No such device. */
 			printf("W1 controller not available.\n");
 			continue;
 		}
 		if (ret) {		/* Other error. */
 			printf("W1 controller probe failed.\n");
 			continue;
 		}
 	}
 	return 0;
 }
 UCLASS_DRIVER(w1) = {
 	.name		= "w1",
 	.id		= UCLASS_W1,
 	.flags		= DM_UC_FLAG_SEQ_ALIAS,
 	.per_device_auto_alloc_size	= sizeof(struct w1_bus),
 	.post_probe	= w1_post_probe,
 #if CONFIG_IS_ENABLED(OF_CONTROL)
 	.post_bind	= dm_scan_fdt_dev,