diff options
| -rw-r--r-- | arch/x86/include/asm/iosf_mbi.h | 39 | ||||
| -rw-r--r-- | arch/x86/platform/intel/iosf_mbi.c | 217 | ||||
| -rw-r--r-- | drivers/i2c/busses/i2c-designware-baytrail.c | 125 |
3 files changed, 230 insertions, 151 deletions
diff --git a/arch/x86/include/asm/iosf_mbi.h b/arch/x86/include/asm/iosf_mbi.h index 3de0489deade..5270ff39b9af 100644 --- a/arch/x86/include/asm/iosf_mbi.h +++ b/arch/x86/include/asm/iosf_mbi.h @@ -105,8 +105,10 @@ int iosf_mbi_modify(u8 port, u8 opcode, u32 offset, u32 mdr, u32 mask); * the PMIC bus while another driver is also accessing the PMIC bus various bad * things happen. * - * To avoid these problems this function must be called before accessing the - * P-Unit or the PMIC, be it through iosf_mbi* functions or through other means. + * Call this function before sending requests to the P-Unit which may make it + * access the PMIC, be it through iosf_mbi* functions or through other means. + * This function will block all kernel access to the PMIC I2C bus, so that the + * P-Unit can safely access the PMIC over the shared I2C bus. * * Note on these systems the i2c-bus driver will request a sempahore from the * P-Unit for exclusive access to the PMIC bus when i2c drivers are accessing @@ -123,6 +125,31 @@ void iosf_mbi_punit_acquire(void); void iosf_mbi_punit_release(void); /** + * iosf_mbi_block_punit_i2c_access() - Block P-Unit accesses to the PMIC bus + * + * Call this function to block P-Unit access to the PMIC I2C bus, so that the + * kernel can safely access the PMIC over the shared I2C bus. + * + * This function acquires the P-Unit bus semaphore and notifies + * pmic_bus_access_notifier listeners that they may no longer access the + * P-Unit in a way which may cause it to access the shared I2C bus. + * + * Note this function may be called multiple times and the bus will not + * be released until iosf_mbi_unblock_punit_i2c_access() has been called the + * same amount of times. + * + * Return: Nonzero on error + */ +int iosf_mbi_block_punit_i2c_access(void); + +/* + * iosf_mbi_unblock_punit_i2c_access() - Release PMIC I2C bus block + * + * Release i2c access block gotten through iosf_mbi_block_punit_i2c_access(). + */ +void iosf_mbi_unblock_punit_i2c_access(void); + +/** * iosf_mbi_register_pmic_bus_access_notifier - Register PMIC bus notifier * * This function can be used by drivers which may need to acquire P-Unit @@ -159,14 +186,6 @@ int iosf_mbi_unregister_pmic_bus_access_notifier_unlocked( struct notifier_block *nb); /** - * iosf_mbi_call_pmic_bus_access_notifier_chain - Call PMIC bus notifier chain - * - * @val: action to pass into listener's notifier_call function - * @v: data pointer to pass into listener's notifier_call function - */ -int iosf_mbi_call_pmic_bus_access_notifier_chain(unsigned long val, void *v); - -/** * iosf_mbi_assert_punit_acquired - Assert that the P-Unit has been acquired. */ void iosf_mbi_assert_punit_acquired(void); diff --git a/arch/x86/platform/intel/iosf_mbi.c b/arch/x86/platform/intel/iosf_mbi.c index 6f37a2137a79..2e569d10f2d0 100644 --- a/arch/x86/platform/intel/iosf_mbi.c +++ b/arch/x86/platform/intel/iosf_mbi.c @@ -18,24 +18,26 @@ * enumerate the device using PCI. */ +#include <linux/delay.h> #include <linux/module.h> #include <linux/init.h> #include <linux/spinlock.h> #include <linux/pci.h> #include <linux/debugfs.h> #include <linux/capability.h> +#include <linux/pm_qos.h> #include <asm/iosf_mbi.h> -#define PCI_DEVICE_ID_BAYTRAIL 0x0F00 -#define PCI_DEVICE_ID_BRASWELL 0x2280 -#define PCI_DEVICE_ID_QUARK_X1000 0x0958 -#define PCI_DEVICE_ID_TANGIER 0x1170 +#define PCI_DEVICE_ID_INTEL_BAYTRAIL 0x0F00 +#define PCI_DEVICE_ID_INTEL_BRASWELL 0x2280 +#define PCI_DEVICE_ID_INTEL_QUARK_X1000 0x0958 +#define PCI_DEVICE_ID_INTEL_TANGIER 0x1170 static struct pci_dev *mbi_pdev; static DEFINE_SPINLOCK(iosf_mbi_lock); -static DEFINE_MUTEX(iosf_mbi_punit_mutex); -static BLOCKING_NOTIFIER_HEAD(iosf_mbi_pmic_bus_access_notifier); + +/**************** Generic iosf_mbi access helpers ****************/ static inline u32 iosf_mbi_form_mcr(u8 op, u8 port, u8 offset) { @@ -192,6 +194,30 @@ bool iosf_mbi_available(void) } EXPORT_SYMBOL(iosf_mbi_available); +/* + **************** P-Unit/kernel shared I2C bus arbritration **************** + * + * 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 + * accesses between the kernel and the P-Unit. + * + * See arch/x86/include/asm/iosf_mbi.h for kernel-doc text for each function. + */ + +#define SEMAPHORE_TIMEOUT 500 +#define PUNIT_SEMAPHORE_BYT 0x7 +#define PUNIT_SEMAPHORE_CHT 0x10e +#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 BLOCKING_NOTIFIER_HEAD(iosf_mbi_pmic_bus_access_notifier); +static u32 iosf_mbi_block_punit_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); @@ -204,6 +230,159 @@ void iosf_mbi_punit_release(void) } EXPORT_SYMBOL(iosf_mbi_punit_release); +static int iosf_mbi_get_sem(u32 *sem) +{ + int ret; + + ret = iosf_mbi_read(BT_MBI_UNIT_PMC, MBI_REG_READ, + iosf_mbi_sem_address, sem); + if (ret) { + dev_err(&mbi_pdev->dev, "Error P-Unit semaphore read failed\n"); + return ret; + } + + *sem &= PUNIT_SEMAPHORE_BIT; + return 0; +} + +static void iosf_mbi_reset_semaphore(void) +{ + if (iosf_mbi_modify(BT_MBI_UNIT_PMC, MBI_REG_READ, + 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); + + blocking_notifier_call_chain(&iosf_mbi_pmic_bus_access_notifier, + MBI_PMIC_BUS_ACCESS_END, NULL); +} + +/* + * This function blocks P-Unit accesses to the PMIC I2C bus, so that kernel + * I2C code, such as e.g. a fuel-gauge driver, can access it safely. + * + * This function may be called by I2C controller code while an I2C driver has + * 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: + * + * 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. + * + * 2) 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 + * 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. + * + * 4) 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. + */ +int iosf_mbi_block_punit_i2c_access(void) +{ + unsigned long start, end; + int ret = 0; + u32 sem; + + if (WARN_ON(!mbi_pdev || !iosf_mbi_sem_address)) + return -ENXIO; + + mutex_lock(&iosf_mbi_block_punit_i2c_access_count_mutex); + + if (iosf_mbi_block_punit_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); + + /* + * Disallow the CPU to enter C6 or C7 state, entering these states + * 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); + + /* host driver writes to side band semaphore register */ + ret = iosf_mbi_write(BT_MBI_UNIT_PMC, MBI_REG_WRITE, + iosf_mbi_sem_address, PUNIT_SEMAPHORE_ACQUIRE); + if (ret) { + dev_err(&mbi_pdev->dev, "Error P-Unit semaphore request failed\n"); + goto error; + } + + /* host driver waits for bit 0 to be set in semaphore register */ + start = jiffies; + end = start + msecs_to_jiffies(SEMAPHORE_TIMEOUT); + do { + ret = iosf_mbi_get_sem(&sem); + if (!ret && sem) { + 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; + } + + usleep_range(1000, 2000); + } while (time_before(jiffies, end)); + + ret = -ETIMEDOUT; + 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++; + + mutex_unlock(&iosf_mbi_block_punit_i2c_access_count_mutex); + + return ret; +} +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); + + iosf_mbi_block_punit_i2c_access_count--; + if (iosf_mbi_block_punit_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)); + } + + mutex_unlock(&iosf_mbi_block_punit_i2c_access_count_mutex); +} +EXPORT_SYMBOL(iosf_mbi_unblock_punit_i2c_access); + int iosf_mbi_register_pmic_bus_access_notifier(struct notifier_block *nb) { int ret; @@ -241,19 +420,14 @@ int iosf_mbi_unregister_pmic_bus_access_notifier(struct notifier_block *nb) } EXPORT_SYMBOL(iosf_mbi_unregister_pmic_bus_access_notifier); -int iosf_mbi_call_pmic_bus_access_notifier_chain(unsigned long val, void *v) -{ - return blocking_notifier_call_chain( - &iosf_mbi_pmic_bus_access_notifier, val, v); -} -EXPORT_SYMBOL(iosf_mbi_call_pmic_bus_access_notifier_chain); - void iosf_mbi_assert_punit_acquired(void) { WARN_ON(!mutex_is_locked(&iosf_mbi_punit_mutex)); } EXPORT_SYMBOL(iosf_mbi_assert_punit_acquired); +/**************** iosf_mbi debug code ****************/ + #ifdef CONFIG_IOSF_MBI_DEBUG static u32 dbg_mdr; static u32 dbg_mcr; @@ -338,7 +512,7 @@ static inline void iosf_debugfs_remove(void) { } #endif /* CONFIG_IOSF_MBI_DEBUG */ static int iosf_mbi_probe(struct pci_dev *pdev, - const struct pci_device_id *unused) + const struct pci_device_id *dev_id) { int ret; @@ -349,14 +523,16 @@ static int iosf_mbi_probe(struct pci_dev *pdev, } mbi_pdev = pci_dev_get(pdev); + iosf_mbi_sem_address = dev_id->driver_data; + return 0; } static const struct pci_device_id iosf_mbi_pci_ids[] = { - { PCI_DEVICE(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_BAYTRAIL) }, - { PCI_DEVICE(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_BRASWELL) }, - { PCI_DEVICE(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_QUARK_X1000) }, - { PCI_DEVICE(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_TANGIER) }, + { PCI_DEVICE_DATA(INTEL, BAYTRAIL, PUNIT_SEMAPHORE_BYT) }, + { PCI_DEVICE_DATA(INTEL, BRASWELL, PUNIT_SEMAPHORE_CHT) }, + { PCI_DEVICE_DATA(INTEL, QUARK_X1000, 0) }, + { PCI_DEVICE_DATA(INTEL, TANGIER, 0) }, { 0, }, }; MODULE_DEVICE_TABLE(pci, iosf_mbi_pci_ids); @@ -371,6 +547,9 @@ 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); + return pci_register_driver(&iosf_mbi_pci_driver); } @@ -381,6 +560,8 @@ static void __exit iosf_mbi_exit(void) pci_unregister_driver(&iosf_mbi_pci_driver); pci_dev_put(mbi_pdev); mbi_pdev = NULL; + + pm_qos_remove_request(&iosf_mbi_pm_qos); } module_init(iosf_mbi_init); diff --git a/drivers/i2c/busses/i2c-designware-baytrail.c b/drivers/i2c/busses/i2c-designware-baytrail.c index a2a275cfc1f6..b2ba4de4e204 100644 --- a/drivers/i2c/busses/i2c-designware-baytrail.c +++ b/drivers/i2c/busses/i2c-designware-baytrail.c @@ -3,139 +3,23 @@ * Intel BayTrail PMIC I2C bus semaphore implementaion * Copyright (c) 2014, Intel Corporation. */ -#include <linux/delay.h> #include <linux/device.h> #include <linux/acpi.h> #include <linux/i2c.h> #include <linux/interrupt.h> -#include <linux/pm_qos.h> #include <asm/iosf_mbi.h> #include "i2c-designware-core.h" -#define SEMAPHORE_TIMEOUT 500 -#define PUNIT_SEMAPHORE 0x7 -#define PUNIT_SEMAPHORE_CHT 0x10e -#define PUNIT_SEMAPHORE_BIT BIT(0) -#define PUNIT_SEMAPHORE_ACQUIRE BIT(1) - -static unsigned long acquired; - -static u32 get_sem_addr(struct dw_i2c_dev *dev) -{ - if (dev->flags & MODEL_CHERRYTRAIL) - return PUNIT_SEMAPHORE_CHT; - else - return PUNIT_SEMAPHORE; -} - -static int get_sem(struct dw_i2c_dev *dev, u32 *sem) -{ - u32 addr = get_sem_addr(dev); - u32 data; - int ret; - - ret = iosf_mbi_read(BT_MBI_UNIT_PMC, MBI_REG_READ, addr, &data); - if (ret) { - dev_err(dev->dev, "iosf failed to read punit semaphore\n"); - return ret; - } - - *sem = data & PUNIT_SEMAPHORE_BIT; - - return 0; -} - -static void reset_semaphore(struct dw_i2c_dev *dev) -{ - if (iosf_mbi_modify(BT_MBI_UNIT_PMC, MBI_REG_READ, get_sem_addr(dev), - 0, PUNIT_SEMAPHORE_BIT)) - dev_err(dev->dev, "iosf failed to reset punit semaphore during write\n"); - - pm_qos_update_request(&dev->pm_qos, PM_QOS_DEFAULT_VALUE); - - iosf_mbi_call_pmic_bus_access_notifier_chain(MBI_PMIC_BUS_ACCESS_END, - NULL); - iosf_mbi_punit_release(); -} - static int baytrail_i2c_acquire(struct dw_i2c_dev *dev) { - u32 addr; - u32 sem = PUNIT_SEMAPHORE_ACQUIRE; - int ret; - unsigned long start, end; - - might_sleep(); - - if (!dev || !dev->dev) - return -ENODEV; - - if (!dev->release_lock) - return 0; - - iosf_mbi_punit_acquire(); - iosf_mbi_call_pmic_bus_access_notifier_chain(MBI_PMIC_BUS_ACCESS_BEGIN, - NULL); - - /* - * Disallow the CPU to enter C6 or C7 state, entering these states - * requires the punit to talk to the pmic and if this happens while - * we're holding the semaphore, the SoC hangs. - */ - pm_qos_update_request(&dev->pm_qos, 0); - - addr = get_sem_addr(dev); - - /* host driver writes to side band semaphore register */ - ret = iosf_mbi_write(BT_MBI_UNIT_PMC, MBI_REG_WRITE, addr, sem); - if (ret) { - dev_err(dev->dev, "iosf punit semaphore request failed\n"); - goto out; - } - - /* host driver waits for bit 0 to be set in semaphore register */ - start = jiffies; - end = start + msecs_to_jiffies(SEMAPHORE_TIMEOUT); - do { - ret = get_sem(dev, &sem); - if (!ret && sem) { - acquired = jiffies; - dev_dbg(dev->dev, "punit semaphore acquired after %ums\n", - jiffies_to_msecs(jiffies - start)); - return 0; - } - - usleep_range(1000, 2000); - } while (time_before(jiffies, end)); - - dev_err(dev->dev, "punit semaphore timed out, resetting\n"); -out: - reset_semaphore(dev); - - ret = iosf_mbi_read(BT_MBI_UNIT_PMC, MBI_REG_READ, addr, &sem); - if (ret) - dev_err(dev->dev, "iosf failed to read punit semaphore\n"); - else - dev_err(dev->dev, "PUNIT SEM: %d\n", sem); - - WARN_ON(1); - - return -ETIMEDOUT; + return iosf_mbi_block_punit_i2c_access(); } static void baytrail_i2c_release(struct dw_i2c_dev *dev) { - if (!dev || !dev->dev) - return; - - if (!dev->acquire_lock) - return; - - reset_semaphore(dev); - dev_dbg(dev->dev, "punit semaphore held for %ums\n", - jiffies_to_msecs(jiffies - acquired)); + iosf_mbi_unblock_punit_i2c_access(); } int i2c_dw_probe_lock_support(struct dw_i2c_dev *dev) @@ -166,14 +50,9 @@ int i2c_dw_probe_lock_support(struct dw_i2c_dev *dev) dev->release_lock = baytrail_i2c_release; dev->pm_disabled = true; - pm_qos_add_request(&dev->pm_qos, PM_QOS_CPU_DMA_LATENCY, - PM_QOS_DEFAULT_VALUE); - return 0; } void i2c_dw_remove_lock_support(struct dw_i2c_dev *dev) { - if (dev->acquire_lock) - pm_qos_remove_request(&dev->pm_qos); } |