diff options
Diffstat (limited to 'arch/x86/platform/intel/iosf_mbi.c')
| -rw-r--r-- | arch/x86/platform/intel/iosf_mbi.c | 162 |
1 files changed, 74 insertions, 88 deletions
diff --git a/arch/x86/platform/intel/iosf_mbi.c b/arch/x86/platform/intel/iosf_mbi.c index a9f2e888e135..40ae94db20d8 100644 --- a/arch/x86/platform/intel/iosf_mbi.c +++ b/arch/x86/platform/intel/iosf_mbi.c @@ -1,17 +1,8 @@ +// SPDX-License-Identifier: GPL-2.0-only /* * IOSF-SB MailBox Interface Driver * Copyright (c) 2013, Intel Corporation. * - * This program is free software; you can redistribute it and/or modify it - * under the terms and conditions of the GNU General Public License, - * version 2, as published by the Free Software Foundation. - * - * This program is distributed in the hope it will be useful, but WITHOUT - * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or - * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for - * more details. - * - * * The IOSF-SB is a fabric bus available on Atom based SOC's that uses a * mailbox interface (MBI) to communicate with multiple devices. This * driver implements access to this interface for those platforms that can @@ -26,6 +17,7 @@ #include <linux/debugfs.h> #include <linux/capability.h> #include <linux/pm_qos.h> +#include <linux/wait.h> #include <asm/iosf_mbi.h> @@ -70,7 +62,7 @@ static int iosf_mbi_pci_read_mdr(u32 mcrx, u32 mcr, u32 *mdr) fail_read: dev_err(&mbi_pdev->dev, "PCI config access failed with %d\n", result); - return result; + return pcibios_err_to_errno(result); } static int iosf_mbi_pci_write_mdr(u32 mcrx, u32 mcr, u32 mdr) @@ -99,7 +91,7 @@ static int iosf_mbi_pci_write_mdr(u32 mcrx, u32 mcr, u32 mdr) fail_write: dev_err(&mbi_pdev->dev, "PCI config access failed with %d\n", result); - return result; + return pcibios_err_to_errno(result); } int iosf_mbi_read(u8 port, u8 opcode, u32 offset, u32 *mdr) @@ -195,7 +187,7 @@ bool iosf_mbi_available(void) EXPORT_SYMBOL(iosf_mbi_available); /* - **************** P-Unit/kernel shared I2C bus arbritration **************** + **************** P-Unit/kernel shared I2C bus arbitration **************** * * Some Bay Trail and Cherry Trail devices have the P-Unit and us (the kernel) * share a single I2C bus to the PMIC. Below are helpers to arbitrate the @@ -210,23 +202,45 @@ EXPORT_SYMBOL(iosf_mbi_available); #define PUNIT_SEMAPHORE_BIT BIT(0) #define PUNIT_SEMAPHORE_ACQUIRE BIT(1) -static DEFINE_MUTEX(iosf_mbi_punit_mutex); -static DEFINE_MUTEX(iosf_mbi_block_punit_i2c_access_count_mutex); +static DEFINE_MUTEX(iosf_mbi_pmic_access_mutex); static BLOCKING_NOTIFIER_HEAD(iosf_mbi_pmic_bus_access_notifier); -static u32 iosf_mbi_block_punit_i2c_access_count; +static DECLARE_WAIT_QUEUE_HEAD(iosf_mbi_pmic_access_waitq); +static u32 iosf_mbi_pmic_punit_access_count; +static u32 iosf_mbi_pmic_i2c_access_count; static u32 iosf_mbi_sem_address; static unsigned long iosf_mbi_sem_acquired; static struct pm_qos_request iosf_mbi_pm_qos; void iosf_mbi_punit_acquire(void) { - mutex_lock(&iosf_mbi_punit_mutex); + /* Wait for any I2C PMIC accesses from in kernel drivers to finish. */ + mutex_lock(&iosf_mbi_pmic_access_mutex); + while (iosf_mbi_pmic_i2c_access_count != 0) { + mutex_unlock(&iosf_mbi_pmic_access_mutex); + wait_event(iosf_mbi_pmic_access_waitq, + iosf_mbi_pmic_i2c_access_count == 0); + mutex_lock(&iosf_mbi_pmic_access_mutex); + } + /* + * We do not need to do anything to allow the PUNIT to safely access + * the PMIC, other then block in kernel accesses to the PMIC. + */ + iosf_mbi_pmic_punit_access_count++; + mutex_unlock(&iosf_mbi_pmic_access_mutex); } EXPORT_SYMBOL(iosf_mbi_punit_acquire); void iosf_mbi_punit_release(void) { - mutex_unlock(&iosf_mbi_punit_mutex); + bool do_wakeup; + + mutex_lock(&iosf_mbi_pmic_access_mutex); + iosf_mbi_pmic_punit_access_count--; + do_wakeup = iosf_mbi_pmic_punit_access_count == 0; + mutex_unlock(&iosf_mbi_pmic_access_mutex); + + if (do_wakeup) + wake_up(&iosf_mbi_pmic_access_waitq); } EXPORT_SYMBOL(iosf_mbi_punit_release); @@ -251,7 +265,7 @@ static void iosf_mbi_reset_semaphore(void) iosf_mbi_sem_address, 0, PUNIT_SEMAPHORE_BIT)) dev_err(&mbi_pdev->dev, "Error P-Unit semaphore reset failed\n"); - pm_qos_update_request(&iosf_mbi_pm_qos, PM_QOS_DEFAULT_VALUE); + cpu_latency_qos_update_request(&iosf_mbi_pm_qos, PM_QOS_DEFAULT_VALUE); blocking_notifier_call_chain(&iosf_mbi_pmic_bus_access_notifier, MBI_PMIC_BUS_ACCESS_END, NULL); @@ -265,34 +279,32 @@ static void iosf_mbi_reset_semaphore(void) * already blocked P-Unit accesses because it wants them blocked over multiple * i2c-transfers, for e.g. read-modify-write of an I2C client register. * - * The P-Unit accesses already being blocked is tracked through the - * iosf_mbi_block_punit_i2c_access_count variable which is protected by the - * iosf_mbi_block_punit_i2c_access_count_mutex this mutex is hold for the - * entire duration of the function. - * - * If access is not blocked yet, this function takes the following steps: + * To allow safe PMIC i2c bus accesses this function takes the following steps: * * 1) Some code sends request to the P-Unit which make it access the PMIC * I2C bus. Testing has shown that the P-Unit does not check its internal * PMIC bus semaphore for these requests. Callers of these requests call * iosf_mbi_punit_acquire()/_release() around their P-Unit accesses, these - * functions lock/unlock the iosf_mbi_punit_mutex. - * As the first step we lock the iosf_mbi_punit_mutex, to wait for any in - * flight requests to finish and to block any new requests. + * functions increase/decrease iosf_mbi_pmic_punit_access_count, so first + * we wait for iosf_mbi_pmic_punit_access_count to become 0. * - * 2) Some code makes such P-Unit requests from atomic contexts where it + * 2) Check iosf_mbi_pmic_i2c_access_count, if access has already + * been blocked by another caller, we only need to increment + * iosf_mbi_pmic_i2c_access_count and we can skip the other steps. + * + * 3) Some code makes such P-Unit requests from atomic contexts where it * cannot call iosf_mbi_punit_acquire() as that may sleep. * As the second step we call a notifier chain which allows any code * needing P-Unit resources from atomic context to acquire them before * we take control over the PMIC I2C bus. * - * 3) When CPU cores enter C6 or C7 the P-Unit needs to talk to the PMIC + * 4) When CPU cores enter C6 or C7 the P-Unit needs to talk to the PMIC * if this happens while the kernel itself is accessing the PMIC I2C bus * the SoC hangs. - * As the third step we call pm_qos_update_request() to disallow the CPU - * to enter C6 or C7. + * As the third step we call cpu_latency_qos_update_request() to disallow the + * CPU to enter C6 or C7. * - * 4) The P-Unit has a PMIC bus semaphore which we can request to stop + * 5) The P-Unit has a PMIC bus semaphore which we can request to stop * autonomous P-Unit tasks from accessing the PMIC I2C bus while we hold it. * As the fourth and final step we request this semaphore and wait for our * request to be acknowledged. @@ -306,12 +318,18 @@ int iosf_mbi_block_punit_i2c_access(void) if (WARN_ON(!mbi_pdev || !iosf_mbi_sem_address)) return -ENXIO; - mutex_lock(&iosf_mbi_block_punit_i2c_access_count_mutex); + mutex_lock(&iosf_mbi_pmic_access_mutex); + + while (iosf_mbi_pmic_punit_access_count != 0) { + mutex_unlock(&iosf_mbi_pmic_access_mutex); + wait_event(iosf_mbi_pmic_access_waitq, + iosf_mbi_pmic_punit_access_count == 0); + mutex_lock(&iosf_mbi_pmic_access_mutex); + } - if (iosf_mbi_block_punit_i2c_access_count > 0) + if (iosf_mbi_pmic_i2c_access_count > 0) goto success; - mutex_lock(&iosf_mbi_punit_mutex); blocking_notifier_call_chain(&iosf_mbi_pmic_bus_access_notifier, MBI_PMIC_BUS_ACCESS_BEGIN, NULL); @@ -320,7 +338,7 @@ int iosf_mbi_block_punit_i2c_access(void) * requires the P-Unit to talk to the PMIC and if this happens while * we're holding the semaphore, the SoC hangs. */ - pm_qos_update_request(&iosf_mbi_pm_qos, 0); + cpu_latency_qos_update_request(&iosf_mbi_pm_qos, 0); /* host driver writes to side band semaphore register */ ret = iosf_mbi_write(BT_MBI_UNIT_PMC, MBI_REG_WRITE, @@ -339,10 +357,6 @@ int iosf_mbi_block_punit_i2c_access(void) iosf_mbi_sem_acquired = jiffies; dev_dbg(&mbi_pdev->dev, "P-Unit semaphore acquired after %ums\n", jiffies_to_msecs(jiffies - start)); - /* - * Success, keep iosf_mbi_punit_mutex locked till - * iosf_mbi_unblock_punit_i2c_access() gets called. - */ goto success; } @@ -353,15 +367,13 @@ int iosf_mbi_block_punit_i2c_access(void) dev_err(&mbi_pdev->dev, "Error P-Unit semaphore timed out, resetting\n"); error: iosf_mbi_reset_semaphore(); - mutex_unlock(&iosf_mbi_punit_mutex); - if (!iosf_mbi_get_sem(&sem)) dev_err(&mbi_pdev->dev, "P-Unit semaphore: %d\n", sem); success: if (!WARN_ON(ret)) - iosf_mbi_block_punit_i2c_access_count++; + iosf_mbi_pmic_i2c_access_count++; - mutex_unlock(&iosf_mbi_block_punit_i2c_access_count_mutex); + mutex_unlock(&iosf_mbi_pmic_access_mutex); return ret; } @@ -369,17 +381,20 @@ EXPORT_SYMBOL(iosf_mbi_block_punit_i2c_access); void iosf_mbi_unblock_punit_i2c_access(void) { - mutex_lock(&iosf_mbi_block_punit_i2c_access_count_mutex); + bool do_wakeup = false; - iosf_mbi_block_punit_i2c_access_count--; - if (iosf_mbi_block_punit_i2c_access_count == 0) { + mutex_lock(&iosf_mbi_pmic_access_mutex); + iosf_mbi_pmic_i2c_access_count--; + if (iosf_mbi_pmic_i2c_access_count == 0) { iosf_mbi_reset_semaphore(); - mutex_unlock(&iosf_mbi_punit_mutex); dev_dbg(&mbi_pdev->dev, "punit semaphore held for %ums\n", jiffies_to_msecs(jiffies - iosf_mbi_sem_acquired)); + do_wakeup = true; } + mutex_unlock(&iosf_mbi_pmic_access_mutex); - mutex_unlock(&iosf_mbi_block_punit_i2c_access_count_mutex); + if (do_wakeup) + wake_up(&iosf_mbi_pmic_access_waitq); } EXPORT_SYMBOL(iosf_mbi_unblock_punit_i2c_access); @@ -388,10 +403,10 @@ int iosf_mbi_register_pmic_bus_access_notifier(struct notifier_block *nb) int ret; /* Wait for the bus to go inactive before registering */ - mutex_lock(&iosf_mbi_punit_mutex); + iosf_mbi_punit_acquire(); ret = blocking_notifier_chain_register( &iosf_mbi_pmic_bus_access_notifier, nb); - mutex_unlock(&iosf_mbi_punit_mutex); + iosf_mbi_punit_release(); return ret; } @@ -407,22 +422,9 @@ int iosf_mbi_unregister_pmic_bus_access_notifier_unlocked( } EXPORT_SYMBOL(iosf_mbi_unregister_pmic_bus_access_notifier_unlocked); -int iosf_mbi_unregister_pmic_bus_access_notifier(struct notifier_block *nb) -{ - int ret; - - /* Wait for the bus to go inactive before unregistering */ - mutex_lock(&iosf_mbi_punit_mutex); - ret = iosf_mbi_unregister_pmic_bus_access_notifier_unlocked(nb); - mutex_unlock(&iosf_mbi_punit_mutex); - - return ret; -} -EXPORT_SYMBOL(iosf_mbi_unregister_pmic_bus_access_notifier); - void iosf_mbi_assert_punit_acquired(void) { - WARN_ON(!mutex_is_locked(&iosf_mbi_punit_mutex)); + WARN_ON(iosf_mbi_pmic_punit_access_count == 0); } EXPORT_SYMBOL(iosf_mbi_assert_punit_acquired); @@ -470,31 +472,16 @@ static struct dentry *iosf_dbg; static void iosf_sideband_debug_init(void) { - struct dentry *d; - iosf_dbg = debugfs_create_dir("iosf_sb", NULL); - if (IS_ERR_OR_NULL(iosf_dbg)) - return; /* mdr */ - d = debugfs_create_x32("mdr", 0660, iosf_dbg, &dbg_mdr); - if (!d) - goto cleanup; + debugfs_create_x32("mdr", 0660, iosf_dbg, &dbg_mdr); /* mcrx */ - d = debugfs_create_x32("mcrx", 0660, iosf_dbg, &dbg_mcrx); - if (!d) - goto cleanup; - - /* mcr - initiates mailbox tranaction */ - d = debugfs_create_file("mcr", 0660, iosf_dbg, &dbg_mcr, &iosf_mcr_fops); - if (!d) - goto cleanup; - - return; + debugfs_create_x32("mcrx", 0660, iosf_dbg, &dbg_mcrx); -cleanup: - debugfs_remove_recursive(d); + /* mcr - initiates mailbox transaction */ + debugfs_create_file("mcr", 0660, iosf_dbg, &dbg_mcr, &iosf_mcr_fops); } static void iosf_debugfs_init(void) @@ -547,8 +534,7 @@ static int __init iosf_mbi_init(void) { iosf_debugfs_init(); - pm_qos_add_request(&iosf_mbi_pm_qos, PM_QOS_CPU_DMA_LATENCY, - PM_QOS_DEFAULT_VALUE); + cpu_latency_qos_add_request(&iosf_mbi_pm_qos, PM_QOS_DEFAULT_VALUE); return pci_register_driver(&iosf_mbi_pci_driver); } @@ -561,7 +547,7 @@ static void __exit iosf_mbi_exit(void) pci_dev_put(mbi_pdev); mbi_pdev = NULL; - pm_qos_remove_request(&iosf_mbi_pm_qos); + cpu_latency_qos_remove_request(&iosf_mbi_pm_qos); } module_init(iosf_mbi_init); |