mirror of
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62b7f5931c
bcm2708: boot tested on RPi B+ v1.2
bcm2709: boot tested on RPi 3B v1.2 and RPi 4B v1.1 4G
bcm2710: boot tested on RPi 3B v1.2
bcm2711: boot tested on RPi 4B v1.1 4G
Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>
(cherry-picked from commit f07e572f64)
150 lines
4.7 KiB
Diff
150 lines
4.7 KiB
Diff
From dfc9fd0060f9103ca1f9335d529401ee8a105737 Mon Sep 17 00:00:00 2001
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From: Akira Shimahara <akira215corp@gmail.com>
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Date: Mon, 11 May 2020 22:36:10 +0200
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Subject: [PATCH] w1_therm: fix reset_select_slave during discovery
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commit c8ad65f6fbfdcb9b620674ef456020eef2bfeb36 upstream.
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Fix reset_select_slave issue during devices discovery by the master on
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bus. The w1_reset_select_slave() from w1_io.c, which was previously used,
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assume that if the slave count is 1 there is only one slave attached on
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the bus. This is not always true. For example when discovering devices,
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when the first device is discover by the bus master, its slave count is
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1, but some other slaves may be on the bus.
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In that case instead of adressing command to the attached slave the
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master throw a SKIP ROM command so that all slaves attached on the bus
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will answer simultenaously causing data collision.
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A dedicated reset_select_slave() function is implemented here,
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it always perform an adressing to each slave using the MATCH ROM
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command.
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Signed-off-by: Akira Shimahara <akira215corp@gmail.com>
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Link: https://lore.kernel.org/r/20200511203610.409975-1-akira215corp@gmail.com
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Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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---
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drivers/w1/slaves/w1_therm.c | 48 ++++++++++++++++++++++++++++++------
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1 file changed, 41 insertions(+), 7 deletions(-)
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--- a/drivers/w1/slaves/w1_therm.c
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+++ b/drivers/w1/slaves/w1_therm.c
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@@ -16,6 +16,7 @@
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#include <linux/slab.h>
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#include <linux/delay.h>
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#include <linux/hwmon.h>
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+#include <linux/string.h>
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#include <linux/w1.h>
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@@ -90,6 +91,24 @@ struct therm_info {
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u8 verdict;
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};
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+/* Hardware Functions declaration */
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+
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+/**
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+ * reset_select_slave() - reset and select a slave
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+ * @sl: the slave to select
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+ *
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+ * Resets the bus and select the slave by sending a ROM MATCH cmd
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+ * w1_reset_select_slave() from w1_io.c could not be used here because
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+ * it sent a SKIP ROM command if only one device is on the line.
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+ * At the beginning of the such process, sl->master->slave_count is 1 even if
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+ * more devices are on the line, causing collision on the line.
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+ *
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+ * Context: The w1 master lock must be held.
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+ *
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+ * Return: 0 if success, negative kernel error code otherwise.
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+ */
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+static int reset_select_slave(struct w1_slave *sl);
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+
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/* Sysfs interface declaration */
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static ssize_t w1_slave_show(struct device *device,
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@@ -301,7 +320,7 @@ static inline int w1_DS18B20_precision(s
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while (max_trying--) {
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crc = 0;
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- if (!w1_reset_select_slave(sl)) {
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+ if (!reset_select_slave(sl)) {
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int count = 0;
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/* read values to only alter precision bits */
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@@ -314,7 +333,7 @@ static inline int w1_DS18B20_precision(s
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if (rom[8] == crc) {
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rom[4] = (rom[4] & ~mask) | (precision_bits & mask);
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- if (!w1_reset_select_slave(sl)) {
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+ if (!reset_select_slave(sl)) {
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w1_write_8(dev, W1_WRITE_SCRATCHPAD);
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w1_write_8(dev, rom[2]);
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w1_write_8(dev, rom[3]);
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@@ -460,6 +479,21 @@ static void w1_therm_remove_slave(struct
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/* Hardware Functions */
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+/* Safe version of reset_select_slave - avoid using the one in w_io.c */
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+static int reset_select_slave(struct w1_slave *sl)
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+{
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+ u8 match[9] = { W1_MATCH_ROM, };
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+ u64 rn = le64_to_cpu(*((u64 *)&sl->reg_num));
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+
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+ if (w1_reset_bus(sl->master))
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+ return -ENODEV;
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+
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+ memcpy(&match[1], &rn, 8);
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+ w1_write_block(sl->master, match, 9);
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+
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+ return 0;
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+}
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+
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static ssize_t read_therm(struct device *device,
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struct w1_slave *sl, struct therm_info *info)
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{
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@@ -487,7 +521,7 @@ static ssize_t read_therm(struct device
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info->verdict = 0;
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info->crc = 0;
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- if (!w1_reset_select_slave(sl)) {
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+ if (!reset_select_slave(sl)) {
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int count = 0;
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unsigned int tm = 750;
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unsigned long sleep_rem;
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@@ -495,7 +529,7 @@ static ssize_t read_therm(struct device
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w1_write_8(dev, W1_READ_PSUPPLY);
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external_power = w1_read_8(dev);
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- if (w1_reset_select_slave(sl))
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+ if (reset_select_slave(sl))
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continue;
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/* 750ms strong pullup (or delay) after the convert */
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@@ -525,7 +559,7 @@ static ssize_t read_therm(struct device
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}
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}
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- if (!w1_reset_select_slave(sl)) {
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+ if (!reset_select_slave(sl)) {
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w1_write_8(dev, W1_READ_SCRATCHPAD);
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count = w1_read_block(dev, info->rom, 9);
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@@ -577,7 +611,7 @@ static inline int w1_therm_eeprom(struct
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memset(rom, 0, sizeof(rom));
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while (max_trying--) {
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- if (!w1_reset_select_slave(sl)) {
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+ if (!reset_select_slave(sl)) {
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unsigned int tm = 10;
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unsigned long sleep_rem;
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@@ -585,7 +619,7 @@ static inline int w1_therm_eeprom(struct
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w1_write_8(dev, W1_READ_PSUPPLY);
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external_power = w1_read_8(dev);
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- if (w1_reset_select_slave(sl))
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+ if (reset_select_slave(sl))
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continue;
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/* 10ms strong pullup/delay after the copy command */
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