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@@ -18,24 +18,26 @@
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* enumerate the device using PCI.
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*/
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+#include <linux/delay.h>
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/spinlock.h>
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#include <linux/pci.h>
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#include <linux/debugfs.h>
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#include <linux/capability.h>
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+#include <linux/pm_qos.h>
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#include <asm/iosf_mbi.h>
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-#define PCI_DEVICE_ID_BAYTRAIL 0x0F00
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-#define PCI_DEVICE_ID_BRASWELL 0x2280
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-#define PCI_DEVICE_ID_QUARK_X1000 0x0958
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-#define PCI_DEVICE_ID_TANGIER 0x1170
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+#define PCI_DEVICE_ID_INTEL_BAYTRAIL 0x0F00
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+#define PCI_DEVICE_ID_INTEL_BRASWELL 0x2280
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+#define PCI_DEVICE_ID_INTEL_QUARK_X1000 0x0958
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+#define PCI_DEVICE_ID_INTEL_TANGIER 0x1170
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static struct pci_dev *mbi_pdev;
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static DEFINE_SPINLOCK(iosf_mbi_lock);
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-static DEFINE_MUTEX(iosf_mbi_punit_mutex);
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-static BLOCKING_NOTIFIER_HEAD(iosf_mbi_pmic_bus_access_notifier);
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+
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+/**************** Generic iosf_mbi access helpers ****************/
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static inline u32 iosf_mbi_form_mcr(u8 op, u8 port, u8 offset)
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{
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@@ -192,6 +194,30 @@ bool iosf_mbi_available(void)
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}
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EXPORT_SYMBOL(iosf_mbi_available);
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+/*
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+ **************** P-Unit/kernel shared I2C bus arbritration ****************
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+ *
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+ * Some Bay Trail and Cherry Trail devices have the P-Unit and us (the kernel)
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+ * share a single I2C bus to the PMIC. Below are helpers to arbitrate the
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+ * accesses between the kernel and the P-Unit.
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+ *
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+ * See arch/x86/include/asm/iosf_mbi.h for kernel-doc text for each function.
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+ */
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+
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+#define SEMAPHORE_TIMEOUT 500
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+#define PUNIT_SEMAPHORE_BYT 0x7
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+#define PUNIT_SEMAPHORE_CHT 0x10e
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+#define PUNIT_SEMAPHORE_BIT BIT(0)
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+#define PUNIT_SEMAPHORE_ACQUIRE BIT(1)
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+
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+static DEFINE_MUTEX(iosf_mbi_punit_mutex);
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+static DEFINE_MUTEX(iosf_mbi_block_punit_i2c_access_count_mutex);
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+static BLOCKING_NOTIFIER_HEAD(iosf_mbi_pmic_bus_access_notifier);
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+static u32 iosf_mbi_block_punit_i2c_access_count;
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+static u32 iosf_mbi_sem_address;
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+static unsigned long iosf_mbi_sem_acquired;
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+static struct pm_qos_request iosf_mbi_pm_qos;
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+
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void iosf_mbi_punit_acquire(void)
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{
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mutex_lock(&iosf_mbi_punit_mutex);
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@@ -204,6 +230,159 @@ void iosf_mbi_punit_release(void)
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}
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EXPORT_SYMBOL(iosf_mbi_punit_release);
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+static int iosf_mbi_get_sem(u32 *sem)
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+{
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+ int ret;
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+
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+ ret = iosf_mbi_read(BT_MBI_UNIT_PMC, MBI_REG_READ,
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+ iosf_mbi_sem_address, sem);
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+ if (ret) {
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+ dev_err(&mbi_pdev->dev, "Error P-Unit semaphore read failed\n");
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+ return ret;
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+ }
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+
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+ *sem &= PUNIT_SEMAPHORE_BIT;
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+ return 0;
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+}
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+
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+static void iosf_mbi_reset_semaphore(void)
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+{
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+ if (iosf_mbi_modify(BT_MBI_UNIT_PMC, MBI_REG_READ,
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+ iosf_mbi_sem_address, 0, PUNIT_SEMAPHORE_BIT))
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+ dev_err(&mbi_pdev->dev, "Error P-Unit semaphore reset failed\n");
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+
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+ pm_qos_update_request(&iosf_mbi_pm_qos, PM_QOS_DEFAULT_VALUE);
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+
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+ blocking_notifier_call_chain(&iosf_mbi_pmic_bus_access_notifier,
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+ MBI_PMIC_BUS_ACCESS_END, NULL);
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+}
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+
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+/*
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+ * This function blocks P-Unit accesses to the PMIC I2C bus, so that kernel
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+ * I2C code, such as e.g. a fuel-gauge driver, can access it safely.
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+ *
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+ * This function may be called by I2C controller code while an I2C driver has
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+ * already blocked P-Unit accesses because it wants them blocked over multiple
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+ * i2c-transfers, for e.g. read-modify-write of an I2C client register.
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+ *
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+ * The P-Unit accesses already being blocked is tracked through the
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+ * iosf_mbi_block_punit_i2c_access_count variable which is protected by the
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+ * iosf_mbi_block_punit_i2c_access_count_mutex this mutex is hold for the
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+ * entire duration of the function.
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+ *
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+ * If access is not blocked yet, this function takes the following steps:
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+ *
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+ * 1) Some code sends request to the P-Unit which make it access the PMIC
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+ * I2C bus. Testing has shown that the P-Unit does not check its internal
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+ * PMIC bus semaphore for these requests. Callers of these requests call
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+ * iosf_mbi_punit_acquire()/_release() around their P-Unit accesses, these
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+ * functions lock/unlock the iosf_mbi_punit_mutex.
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+ * As the first step we lock the iosf_mbi_punit_mutex, to wait for any in
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+ * flight requests to finish and to block any new requests.
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+ *
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+ * 2) Some code makes such P-Unit requests from atomic contexts where it
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+ * cannot call iosf_mbi_punit_acquire() as that may sleep.
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+ * As the second step we call a notifier chain which allows any code
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+ * needing P-Unit resources from atomic context to acquire them before
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+ * we take control over the PMIC I2C bus.
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+ *
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+ * 3) When CPU cores enter C6 or C7 the P-Unit needs to talk to the PMIC
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+ * if this happens while the kernel itself is accessing the PMIC I2C bus
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+ * the SoC hangs.
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+ * As the third step we call pm_qos_update_request() to disallow the CPU
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+ * to enter C6 or C7.
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+ *
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+ * 4) The P-Unit has a PMIC bus semaphore which we can request to stop
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+ * autonomous P-Unit tasks from accessing the PMIC I2C bus while we hold it.
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+ * As the fourth and final step we request this semaphore and wait for our
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+ * request to be acknowledged.
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+ */
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+int iosf_mbi_block_punit_i2c_access(void)
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+{
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+ unsigned long start, end;
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+ int ret = 0;
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+ u32 sem;
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+
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+ if (WARN_ON(!mbi_pdev || !iosf_mbi_sem_address))
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+ return -ENXIO;
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+
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+ mutex_lock(&iosf_mbi_block_punit_i2c_access_count_mutex);
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+
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+ if (iosf_mbi_block_punit_i2c_access_count > 0)
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+ goto success;
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+
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+ mutex_lock(&iosf_mbi_punit_mutex);
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+ blocking_notifier_call_chain(&iosf_mbi_pmic_bus_access_notifier,
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+ MBI_PMIC_BUS_ACCESS_BEGIN, NULL);
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+
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+ /*
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+ * Disallow the CPU to enter C6 or C7 state, entering these states
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+ * requires the P-Unit to talk to the PMIC and if this happens while
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+ * we're holding the semaphore, the SoC hangs.
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+ */
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+ pm_qos_update_request(&iosf_mbi_pm_qos, 0);
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+
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+ /* host driver writes to side band semaphore register */
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+ ret = iosf_mbi_write(BT_MBI_UNIT_PMC, MBI_REG_WRITE,
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+ iosf_mbi_sem_address, PUNIT_SEMAPHORE_ACQUIRE);
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+ if (ret) {
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+ dev_err(&mbi_pdev->dev, "Error P-Unit semaphore request failed\n");
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+ goto error;
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+ }
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+
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+ /* host driver waits for bit 0 to be set in semaphore register */
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+ start = jiffies;
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+ end = start + msecs_to_jiffies(SEMAPHORE_TIMEOUT);
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+ do {
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+ ret = iosf_mbi_get_sem(&sem);
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+ if (!ret && sem) {
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+ iosf_mbi_sem_acquired = jiffies;
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+ dev_dbg(&mbi_pdev->dev, "P-Unit semaphore acquired after %ums\n",
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+ jiffies_to_msecs(jiffies - start));
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+ /*
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+ * Success, keep iosf_mbi_punit_mutex locked till
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+ * iosf_mbi_unblock_punit_i2c_access() gets called.
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+ */
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+ goto success;
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+ }
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+
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+ usleep_range(1000, 2000);
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+ } while (time_before(jiffies, end));
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+
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+ ret = -ETIMEDOUT;
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+ dev_err(&mbi_pdev->dev, "Error P-Unit semaphore timed out, resetting\n");
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+error:
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+ iosf_mbi_reset_semaphore();
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+ mutex_unlock(&iosf_mbi_punit_mutex);
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+
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+ if (!iosf_mbi_get_sem(&sem))
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+ dev_err(&mbi_pdev->dev, "P-Unit semaphore: %d\n", sem);
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+success:
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+ if (!WARN_ON(ret))
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+ iosf_mbi_block_punit_i2c_access_count++;
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+
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+ mutex_unlock(&iosf_mbi_block_punit_i2c_access_count_mutex);
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+
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+ return ret;
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+}
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+EXPORT_SYMBOL(iosf_mbi_block_punit_i2c_access);
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+
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+void iosf_mbi_unblock_punit_i2c_access(void)
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+{
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+ mutex_lock(&iosf_mbi_block_punit_i2c_access_count_mutex);
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+
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+ iosf_mbi_block_punit_i2c_access_count--;
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+ if (iosf_mbi_block_punit_i2c_access_count == 0) {
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+ iosf_mbi_reset_semaphore();
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+ mutex_unlock(&iosf_mbi_punit_mutex);
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+ dev_dbg(&mbi_pdev->dev, "punit semaphore held for %ums\n",
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+ jiffies_to_msecs(jiffies - iosf_mbi_sem_acquired));
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+ }
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+
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+ mutex_unlock(&iosf_mbi_block_punit_i2c_access_count_mutex);
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+}
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+EXPORT_SYMBOL(iosf_mbi_unblock_punit_i2c_access);
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+
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int iosf_mbi_register_pmic_bus_access_notifier(struct notifier_block *nb)
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{
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int ret;
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@@ -241,19 +420,14 @@ int iosf_mbi_unregister_pmic_bus_access_notifier(struct notifier_block *nb)
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}
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EXPORT_SYMBOL(iosf_mbi_unregister_pmic_bus_access_notifier);
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-int iosf_mbi_call_pmic_bus_access_notifier_chain(unsigned long val, void *v)
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-{
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- return blocking_notifier_call_chain(
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- &iosf_mbi_pmic_bus_access_notifier, val, v);
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-}
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-EXPORT_SYMBOL(iosf_mbi_call_pmic_bus_access_notifier_chain);
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-
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void iosf_mbi_assert_punit_acquired(void)
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{
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WARN_ON(!mutex_is_locked(&iosf_mbi_punit_mutex));
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}
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EXPORT_SYMBOL(iosf_mbi_assert_punit_acquired);
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+/**************** iosf_mbi debug code ****************/
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+
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#ifdef CONFIG_IOSF_MBI_DEBUG
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static u32 dbg_mdr;
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static u32 dbg_mcr;
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@@ -338,7 +512,7 @@ static inline void iosf_debugfs_remove(void) { }
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#endif /* CONFIG_IOSF_MBI_DEBUG */
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static int iosf_mbi_probe(struct pci_dev *pdev,
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- const struct pci_device_id *unused)
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+ const struct pci_device_id *dev_id)
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{
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int ret;
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@@ -349,14 +523,16 @@ static int iosf_mbi_probe(struct pci_dev *pdev,
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}
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mbi_pdev = pci_dev_get(pdev);
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+ iosf_mbi_sem_address = dev_id->driver_data;
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+
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return 0;
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}
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static const struct pci_device_id iosf_mbi_pci_ids[] = {
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- { PCI_DEVICE(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_BAYTRAIL) },
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- { PCI_DEVICE(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_BRASWELL) },
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- { PCI_DEVICE(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_QUARK_X1000) },
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- { PCI_DEVICE(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_TANGIER) },
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+ { PCI_DEVICE_DATA(INTEL, BAYTRAIL, PUNIT_SEMAPHORE_BYT) },
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+ { PCI_DEVICE_DATA(INTEL, BRASWELL, PUNIT_SEMAPHORE_CHT) },
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+ { PCI_DEVICE_DATA(INTEL, QUARK_X1000, 0) },
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+ { PCI_DEVICE_DATA(INTEL, TANGIER, 0) },
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{ 0, },
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};
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MODULE_DEVICE_TABLE(pci, iosf_mbi_pci_ids);
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@@ -371,6 +547,9 @@ static int __init iosf_mbi_init(void)
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{
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iosf_debugfs_init();
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+ pm_qos_add_request(&iosf_mbi_pm_qos, PM_QOS_CPU_DMA_LATENCY,
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+ PM_QOS_DEFAULT_VALUE);
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+
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return pci_register_driver(&iosf_mbi_pci_driver);
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}
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@@ -381,6 +560,8 @@ static void __exit iosf_mbi_exit(void)
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pci_unregister_driver(&iosf_mbi_pci_driver);
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pci_dev_put(mbi_pdev);
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mbi_pdev = NULL;
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+
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+ pm_qos_remove_request(&iosf_mbi_pm_qos);
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}
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module_init(iosf_mbi_init);
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