From 60466c067927abbcaff299845abd4b7069963139 Mon Sep 17 00:00:00 2001 From: Benjamin Bara Date: Sat, 15 Jul 2023 09:53:23 +0200 Subject: kernel/reboot: emergency_restart: Set correct system_state As the emergency restart does not call kernel_restart_prepare(), the system_state stays in SYSTEM_RUNNING. Since bae1d3a05a8b, this hinders i2c_in_atomic_xfer_mode() from becoming active, and therefore might lead to avoidable warnings in the restart handlers, e.g.: [ 12.667612] WARNING: CPU: 1 PID: 1 at kernel/rcu/tree_plugin.h:318 rcu_note_context_switch+0x33c/0x6b0 [ 12.676926] Voluntary context switch within RCU read-side critical section! ... [ 12.742376] schedule_timeout from wait_for_completion_timeout+0x90/0x114 [ 12.749179] wait_for_completion_timeout from tegra_i2c_wait_completion+0x40/0x70 ... [ 12.994527] atomic_notifier_call_chain from machine_restart+0x34/0x58 [ 13.001050] machine_restart from panic+0x2a8/0x32c Avoid these by setting the correct system_state. Fixes: bae1d3a05a8b ("i2c: core: remove use of in_atomic()") Cc: stable@vger.kernel.org # v5.2+ Reviewed-by: Dmitry Osipenko Tested-by: Nishanth Menon Signed-off-by: Benjamin Bara Link: https://lore.kernel.org/r/20230327-tegra-pmic-reboot-v7-1-18699d5dcd76@skidata.com Signed-off-by: Lee Jones --- kernel/reboot.c | 1 + 1 file changed, 1 insertion(+) diff --git a/kernel/reboot.c b/kernel/reboot.c index 3bba88c7ffc6..6ebef11c8876 100644 --- a/kernel/reboot.c +++ b/kernel/reboot.c @@ -74,6 +74,7 @@ void __weak (*pm_power_off)(void); void emergency_restart(void) { kmsg_dump(KMSG_DUMP_EMERG); + system_state = SYSTEM_RESTART; machine_emergency_restart(); } EXPORT_SYMBOL_GPL(emergency_restart); -- cgit From aa49c90894d06e18a1ee7c095edbd2f37c232d02 Mon Sep 17 00:00:00 2001 From: Benjamin Bara Date: Sat, 15 Jul 2023 09:53:24 +0200 Subject: i2c: core: Run atomic i2c xfer when !preemptible Since bae1d3a05a8b, i2c transfers are non-atomic if preemption is disabled. However, non-atomic i2c transfers require preemption (e.g. in wait_for_completion() while waiting for the DMA). panic() calls preempt_disable_notrace() before calling emergency_restart(). Therefore, if an i2c device is used for the restart, the xfer should be atomic. This avoids warnings like: [ 12.667612] WARNING: CPU: 1 PID: 1 at kernel/rcu/tree_plugin.h:318 rcu_note_context_switch+0x33c/0x6b0 [ 12.676926] Voluntary context switch within RCU read-side critical section! ... [ 12.742376] schedule_timeout from wait_for_completion_timeout+0x90/0x114 [ 12.749179] wait_for_completion_timeout from tegra_i2c_wait_completion+0x40/0x70 ... [ 12.994527] atomic_notifier_call_chain from machine_restart+0x34/0x58 [ 13.001050] machine_restart from panic+0x2a8/0x32c Use !preemptible() instead, which is basically the same check as pre-v5.2. Fixes: bae1d3a05a8b ("i2c: core: remove use of in_atomic()") Cc: stable@vger.kernel.org # v5.2+ Suggested-by: Dmitry Osipenko Acked-by: Wolfram Sang Reviewed-by: Dmitry Osipenko Tested-by: Nishanth Menon Signed-off-by: Benjamin Bara Link: https://lore.kernel.org/r/20230327-tegra-pmic-reboot-v7-2-18699d5dcd76@skidata.com Signed-off-by: Lee Jones --- drivers/i2c/i2c-core.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/i2c/i2c-core.h b/drivers/i2c/i2c-core.h index 1247e6e6e975..05b8b8dfa9bd 100644 --- a/drivers/i2c/i2c-core.h +++ b/drivers/i2c/i2c-core.h @@ -29,7 +29,7 @@ int i2c_dev_irq_from_resources(const struct resource *resources, */ static inline bool i2c_in_atomic_xfer_mode(void) { - return system_state > SYSTEM_RUNNING && irqs_disabled(); + return system_state > SYSTEM_RUNNING && !preemptible(); } static inline int __i2c_lock_bus_helper(struct i2c_adapter *adap) -- cgit From db2d6038c5e795cab4f0a8d3e86b4f7e33338629 Mon Sep 17 00:00:00 2001 From: Benjamin Bara Date: Sat, 15 Jul 2023 09:53:25 +0200 Subject: kernel/reboot: Add device to sys_off_handler If the dev is known (e.g. a devm-based sys_off_handler is used), it can be passed to the handler's callback to have it available there. Otherwise, cb_data might be set to the dev in most of the cases. Reviewed-by: Dmitry Osipenko Signed-off-by: Benjamin Bara Link: https://lore.kernel.org/r/20230327-tegra-pmic-reboot-v7-3-18699d5dcd76@skidata.com Signed-off-by: Lee Jones --- include/linux/reboot.h | 3 +++ kernel/reboot.c | 3 +++ 2 files changed, 6 insertions(+) diff --git a/include/linux/reboot.h b/include/linux/reboot.h index 2b6bb593be5b..c4cc3b89ced1 100644 --- a/include/linux/reboot.h +++ b/include/linux/reboot.h @@ -129,11 +129,14 @@ enum sys_off_mode { * @cb_data: User's callback data. * @cmd: Command string. Currently used only by the sys-off restart mode, * NULL otherwise. + * @dev: Device of the sys-off handler. Only if known (devm_register_*), + * NULL otherwise. */ struct sys_off_data { int mode; void *cb_data; const char *cmd; + struct device *dev; }; struct sys_off_handler * diff --git a/kernel/reboot.c b/kernel/reboot.c index 6ebef11c8876..395a0ea3c7a8 100644 --- a/kernel/reboot.c +++ b/kernel/reboot.c @@ -55,6 +55,7 @@ struct sys_off_handler { enum sys_off_mode mode; bool blocking; void *list; + struct device *dev; }; /* @@ -324,6 +325,7 @@ static int sys_off_notify(struct notifier_block *nb, data.cb_data = handler->cb_data; data.mode = mode; data.cmd = cmd; + data.dev = handler->dev; return handler->sys_off_cb(&data); } @@ -511,6 +513,7 @@ int devm_register_sys_off_handler(struct device *dev, handler = register_sys_off_handler(mode, priority, callback, cb_data); if (IS_ERR(handler)) return PTR_ERR(handler); + handler->dev = dev; return devm_add_action_or_reset(dev, devm_unregister_sys_off_handler, handler); -- cgit From 8bd141b17cedcbcb7d336df6e0462e4f4a528ab1 Mon Sep 17 00:00:00 2001 From: Benjamin Bara Date: Sat, 15 Jul 2023 09:53:26 +0200 Subject: mfd: tps6586x: Use devm-based power off handler Convert the power off handler to a devm-based power off handler. Reviewed-by: Dmitry Osipenko Signed-off-by: Benjamin Bara Link: https://lore.kernel.org/r/20230327-tegra-pmic-reboot-v7-4-18699d5dcd76@skidata.com Signed-off-by: Lee Jones --- drivers/mfd/tps6586x.c | 29 +++++++++++++++++++++-------- 1 file changed, 21 insertions(+), 8 deletions(-) diff --git a/drivers/mfd/tps6586x.c b/drivers/mfd/tps6586x.c index 55675ceedcd3..965065562de6 100644 --- a/drivers/mfd/tps6586x.c +++ b/drivers/mfd/tps6586x.c @@ -22,6 +22,7 @@ #include #include #include +#include #include #include @@ -457,13 +458,21 @@ static const struct regmap_config tps6586x_regmap_config = { .cache_type = REGCACHE_RBTREE, }; -static struct device *tps6586x_dev; -static void tps6586x_power_off(void) +static int tps6586x_power_off_handler(struct sys_off_data *data) { - if (tps6586x_clr_bits(tps6586x_dev, TPS6586X_SUPPLYENE, EXITSLREQ_BIT)) - return; + int ret; + + /* Put the PMIC into sleep state. This takes at least 20ms. */ + ret = tps6586x_clr_bits(data->dev, TPS6586X_SUPPLYENE, EXITSLREQ_BIT); + if (ret) + return notifier_from_errno(ret); + + ret = tps6586x_set_bits(data->dev, TPS6586X_SUPPLYENE, SLEEP_MODE_BIT); + if (ret) + return notifier_from_errno(ret); - tps6586x_set_bits(tps6586x_dev, TPS6586X_SUPPLYENE, SLEEP_MODE_BIT); + mdelay(50); + return notifier_from_errno(-ETIME); } static void tps6586x_print_version(struct i2c_client *client, int version) @@ -559,9 +568,13 @@ static int tps6586x_i2c_probe(struct i2c_client *client) goto err_add_devs; } - if (pdata->pm_off && !pm_power_off) { - tps6586x_dev = &client->dev; - pm_power_off = tps6586x_power_off; + if (pdata->pm_off) { + ret = devm_register_power_off_handler(&client->dev, &tps6586x_power_off_handler, + NULL); + if (ret) { + dev_err(&client->dev, "register power off handler failed: %d\n", ret); + goto err_add_devs; + } } return 0; -- cgit From 510f276df2b91efd73f6c53be62b7e692ff533c1 Mon Sep 17 00:00:00 2001 From: Benjamin Bara Date: Sat, 15 Jul 2023 09:53:27 +0200 Subject: mfd: tps6586x: Register restart handler There are a couple of boards which use a tps6586x as "ti,system-power-controller", e.g. the tegra20-tamonten.dtsi. For these, the only registered restart handler is the warm reboot via tegra's PMC. As the bootloader of the tegra20 requires the VDE, it must be ensured that VDE is enabled (which is the case after a cold reboot). For the "normal reboot", this is basically the case since 8f0c714ad9be. However, this workaround is not executed in case of an emergency restart. In case of an emergency restart, the system now simply hangs in the bootloader, as VDE is not enabled (because it is not used). The TPS658629-Q1 provides a SOFT RST bit in the SUPPLYENE reg to request a (cold) reboot, which takes at least 20ms (as the data sheet states). This avoids the hang-up. Tested on a TPS658640. Reviewed-by: Dmitry Osipenko Signed-off-by: Benjamin Bara Link: https://lore.kernel.org/r/20230327-tegra-pmic-reboot-v7-5-18699d5dcd76@skidata.com Signed-off-by: Lee Jones --- drivers/mfd/tps6586x.c | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) diff --git a/drivers/mfd/tps6586x.c b/drivers/mfd/tps6586x.c index 965065562de6..7e8160b94784 100644 --- a/drivers/mfd/tps6586x.c +++ b/drivers/mfd/tps6586x.c @@ -30,6 +30,7 @@ #include #define TPS6586X_SUPPLYENE 0x14 +#define SOFT_RST_BIT BIT(0) #define EXITSLREQ_BIT BIT(1) #define SLEEP_MODE_BIT BIT(3) @@ -475,6 +476,19 @@ static int tps6586x_power_off_handler(struct sys_off_data *data) return notifier_from_errno(-ETIME); } +static int tps6586x_restart_handler(struct sys_off_data *data) +{ + int ret; + + /* Put the PMIC into hard reboot state. This takes at least 20ms. */ + ret = tps6586x_set_bits(data->dev, TPS6586X_SUPPLYENE, SOFT_RST_BIT); + if (ret) + return notifier_from_errno(ret); + + mdelay(50); + return notifier_from_errno(-ETIME); +} + static void tps6586x_print_version(struct i2c_client *client, int version) { const char *name; @@ -575,6 +589,13 @@ static int tps6586x_i2c_probe(struct i2c_client *client) dev_err(&client->dev, "register power off handler failed: %d\n", ret); goto err_add_devs; } + + ret = devm_register_restart_handler(&client->dev, &tps6586x_restart_handler, + NULL); + if (ret) { + dev_err(&client->dev, "register restart handler failed: %d\n", ret); + goto err_add_devs; + } } return 0; -- cgit