* 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
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
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);
* 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)
{
}
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);
}
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;
}
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;
#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;
}
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);
{
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);
}
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);
* 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;
-}
-
-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));
-}
-
int i2c_dw_probe_lock_support(struct dw_i2c_dev *dev)
{
acpi_status status;
return -EPROBE_DEFER;
dev_info(dev->dev, "I2C bus managed by PUNIT\n");
- dev->acquire_lock = baytrail_i2c_acquire;
- dev->release_lock = baytrail_i2c_release;
+ dev->acquire_lock = iosf_mbi_block_punit_i2c_access;
+ dev->release_lock = iosf_mbi_unblock_punit_i2c_access;
dev->shared_with_punit = 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);
-}
projects / platform / kernel / linux-starfive.git / commitdiff