diff options
Diffstat (limited to 'arch/x86/platform/intel/iosf_mbi.c')
| -rw-r--r-- | arch/x86/platform/intel/iosf_mbi.c | 571 |
1 files changed, 571 insertions, 0 deletions
diff --git a/arch/x86/platform/intel/iosf_mbi.c b/arch/x86/platform/intel/iosf_mbi.c new file mode 100644 index 000000000..fdd49d70b --- /dev/null +++ b/arch/x86/platform/intel/iosf_mbi.c @@ -0,0 +1,571 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * IOSF-SB MailBox Interface Driver + * Copyright (c) 2013, Intel Corporation. + * + * 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 + * 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 <linux/wait.h> + +#include <asm/iosf_mbi.h> + +#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); + +/**************** Generic iosf_mbi access helpers ****************/ + +static inline u32 iosf_mbi_form_mcr(u8 op, u8 port, u8 offset) +{ + return (op << 24) | (port << 16) | (offset << 8) | MBI_ENABLE; +} + +static int iosf_mbi_pci_read_mdr(u32 mcrx, u32 mcr, u32 *mdr) +{ + int result; + + if (!mbi_pdev) + return -ENODEV; + + if (mcrx) { + result = pci_write_config_dword(mbi_pdev, MBI_MCRX_OFFSET, + mcrx); + if (result < 0) + goto fail_read; + } + + result = pci_write_config_dword(mbi_pdev, MBI_MCR_OFFSET, mcr); + if (result < 0) + goto fail_read; + + result = pci_read_config_dword(mbi_pdev, MBI_MDR_OFFSET, mdr); + if (result < 0) + goto fail_read; + + return 0; + +fail_read: + dev_err(&mbi_pdev->dev, "PCI config access failed with %d\n", result); + return result; +} + +static int iosf_mbi_pci_write_mdr(u32 mcrx, u32 mcr, u32 mdr) +{ + int result; + + if (!mbi_pdev) + return -ENODEV; + + result = pci_write_config_dword(mbi_pdev, MBI_MDR_OFFSET, mdr); + if (result < 0) + goto fail_write; + + if (mcrx) { + result = pci_write_config_dword(mbi_pdev, MBI_MCRX_OFFSET, + mcrx); + if (result < 0) + goto fail_write; + } + + result = pci_write_config_dword(mbi_pdev, MBI_MCR_OFFSET, mcr); + if (result < 0) + goto fail_write; + + return 0; + +fail_write: + dev_err(&mbi_pdev->dev, "PCI config access failed with %d\n", result); + return result; +} + +int iosf_mbi_read(u8 port, u8 opcode, u32 offset, u32 *mdr) +{ + u32 mcr, mcrx; + unsigned long flags; + int ret; + + /* Access to the GFX unit is handled by GPU code */ + if (port == BT_MBI_UNIT_GFX) { + WARN_ON(1); + return -EPERM; + } + + mcr = iosf_mbi_form_mcr(opcode, port, offset & MBI_MASK_LO); + mcrx = offset & MBI_MASK_HI; + + spin_lock_irqsave(&iosf_mbi_lock, flags); + ret = iosf_mbi_pci_read_mdr(mcrx, mcr, mdr); + spin_unlock_irqrestore(&iosf_mbi_lock, flags); + + return ret; +} +EXPORT_SYMBOL(iosf_mbi_read); + +int iosf_mbi_write(u8 port, u8 opcode, u32 offset, u32 mdr) +{ + u32 mcr, mcrx; + unsigned long flags; + int ret; + + /* Access to the GFX unit is handled by GPU code */ + if (port == BT_MBI_UNIT_GFX) { + WARN_ON(1); + return -EPERM; + } + + mcr = iosf_mbi_form_mcr(opcode, port, offset & MBI_MASK_LO); + mcrx = offset & MBI_MASK_HI; + + spin_lock_irqsave(&iosf_mbi_lock, flags); + ret = iosf_mbi_pci_write_mdr(mcrx, mcr, mdr); + spin_unlock_irqrestore(&iosf_mbi_lock, flags); + + return ret; +} +EXPORT_SYMBOL(iosf_mbi_write); + +int iosf_mbi_modify(u8 port, u8 opcode, u32 offset, u32 mdr, u32 mask) +{ + u32 mcr, mcrx; + u32 value; + unsigned long flags; + int ret; + + /* Access to the GFX unit is handled by GPU code */ + if (port == BT_MBI_UNIT_GFX) { + WARN_ON(1); + return -EPERM; + } + + mcr = iosf_mbi_form_mcr(opcode, port, offset & MBI_MASK_LO); + mcrx = offset & MBI_MASK_HI; + + spin_lock_irqsave(&iosf_mbi_lock, flags); + + /* Read current mdr value */ + ret = iosf_mbi_pci_read_mdr(mcrx, mcr & MBI_RD_MASK, &value); + if (ret < 0) { + spin_unlock_irqrestore(&iosf_mbi_lock, flags); + return ret; + } + + /* Apply mask */ + value &= ~mask; + mdr &= mask; + value |= mdr; + + /* Write back */ + ret = iosf_mbi_pci_write_mdr(mcrx, mcr | MBI_WR_MASK, value); + + spin_unlock_irqrestore(&iosf_mbi_lock, flags); + + return ret; +} +EXPORT_SYMBOL(iosf_mbi_modify); + +bool iosf_mbi_available(void) +{ + /* Mbi isn't hot-pluggable. No remove routine is provided */ + return mbi_pdev; +} +EXPORT_SYMBOL(iosf_mbi_available); + +/* + **************** 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 + * 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_pmic_access_mutex); +static BLOCKING_NOTIFIER_HEAD(iosf_mbi_pmic_bus_access_notifier); +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) +{ + /* 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) +{ + 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); + +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"); + + 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); +} + +/* + * 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. + * + * 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 increase/decrease iosf_mbi_pmic_punit_access_count, so first + * we wait for iosf_mbi_pmic_punit_access_count to become 0. + * + * 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. + * + * 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 cpu_latency_qos_update_request() to disallow the + * CPU to enter C6 or C7. + * + * 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. + */ +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_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_pmic_i2c_access_count > 0) + goto success; + + 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. + */ + 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, + 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)); + 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(); + if (!iosf_mbi_get_sem(&sem)) + dev_err(&mbi_pdev->dev, "P-Unit semaphore: %d\n", sem); +success: + if (!WARN_ON(ret)) + iosf_mbi_pmic_i2c_access_count++; + + mutex_unlock(&iosf_mbi_pmic_access_mutex); + + return ret; +} +EXPORT_SYMBOL(iosf_mbi_block_punit_i2c_access); + +void iosf_mbi_unblock_punit_i2c_access(void) +{ + bool do_wakeup = false; + + 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(); + 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); + + if (do_wakeup) + wake_up(&iosf_mbi_pmic_access_waitq); +} +EXPORT_SYMBOL(iosf_mbi_unblock_punit_i2c_access); + +int iosf_mbi_register_pmic_bus_access_notifier(struct notifier_block *nb) +{ + int ret; + + /* Wait for the bus to go inactive before registering */ + iosf_mbi_punit_acquire(); + ret = blocking_notifier_chain_register( + &iosf_mbi_pmic_bus_access_notifier, nb); + iosf_mbi_punit_release(); + + return ret; +} +EXPORT_SYMBOL(iosf_mbi_register_pmic_bus_access_notifier); + +int iosf_mbi_unregister_pmic_bus_access_notifier_unlocked( + struct notifier_block *nb) +{ + iosf_mbi_assert_punit_acquired(); + + return blocking_notifier_chain_unregister( + &iosf_mbi_pmic_bus_access_notifier, nb); +} +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 */ + iosf_mbi_punit_acquire(); + ret = iosf_mbi_unregister_pmic_bus_access_notifier_unlocked(nb); + iosf_mbi_punit_release(); + + return ret; +} +EXPORT_SYMBOL(iosf_mbi_unregister_pmic_bus_access_notifier); + +void iosf_mbi_assert_punit_acquired(void) +{ + WARN_ON(iosf_mbi_pmic_punit_access_count == 0); +} +EXPORT_SYMBOL(iosf_mbi_assert_punit_acquired); + +/**************** iosf_mbi debug code ****************/ + +#ifdef CONFIG_IOSF_MBI_DEBUG +static u32 dbg_mdr; +static u32 dbg_mcr; +static u32 dbg_mcrx; + +static int mcr_get(void *data, u64 *val) +{ + *val = *(u32 *)data; + return 0; +} + +static int mcr_set(void *data, u64 val) +{ + u8 command = ((u32)val & 0xFF000000) >> 24, + port = ((u32)val & 0x00FF0000) >> 16, + offset = ((u32)val & 0x0000FF00) >> 8; + int err; + + *(u32 *)data = val; + + if (!capable(CAP_SYS_RAWIO)) + return -EACCES; + + if (command & 1u) + err = iosf_mbi_write(port, + command, + dbg_mcrx | offset, + dbg_mdr); + else + err = iosf_mbi_read(port, + command, + dbg_mcrx | offset, + &dbg_mdr); + + return err; +} +DEFINE_SIMPLE_ATTRIBUTE(iosf_mcr_fops, mcr_get, mcr_set , "%llx\n"); + +static struct dentry *iosf_dbg; + +static void iosf_sideband_debug_init(void) +{ + iosf_dbg = debugfs_create_dir("iosf_sb", NULL); + + /* mdr */ + debugfs_create_x32("mdr", 0660, iosf_dbg, &dbg_mdr); + + /* mcrx */ + debugfs_create_x32("mcrx", 0660, iosf_dbg, &dbg_mcrx); + + /* mcr - initiates mailbox transaction */ + debugfs_create_file("mcr", 0660, iosf_dbg, &dbg_mcr, &iosf_mcr_fops); +} + +static void iosf_debugfs_init(void) +{ + iosf_sideband_debug_init(); +} + +static void iosf_debugfs_remove(void) +{ + debugfs_remove_recursive(iosf_dbg); +} +#else +static inline void iosf_debugfs_init(void) { } +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 *dev_id) +{ + int ret; + + ret = pci_enable_device(pdev); + if (ret < 0) { + dev_err(&pdev->dev, "error: could not enable device\n"); + return ret; + } + + 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_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); + +static struct pci_driver iosf_mbi_pci_driver = { + .name = "iosf_mbi_pci", + .probe = iosf_mbi_probe, + .id_table = iosf_mbi_pci_ids, +}; + +static int __init iosf_mbi_init(void) +{ + iosf_debugfs_init(); + + cpu_latency_qos_add_request(&iosf_mbi_pm_qos, PM_QOS_DEFAULT_VALUE); + + return pci_register_driver(&iosf_mbi_pci_driver); +} + +static void __exit iosf_mbi_exit(void) +{ + iosf_debugfs_remove(); + + pci_unregister_driver(&iosf_mbi_pci_driver); + pci_dev_put(mbi_pdev); + mbi_pdev = NULL; + + cpu_latency_qos_remove_request(&iosf_mbi_pm_qos); +} + +module_init(iosf_mbi_init); +module_exit(iosf_mbi_exit); + +MODULE_AUTHOR("David E. Box <david.e.box@linux.intel.com>"); +MODULE_DESCRIPTION("IOSF Mailbox Interface accessor"); +MODULE_LICENSE("GPL v2"); |