2 files changed, 573 insertions, 0 deletions
diff --git a/arch/x86/platform/intel/Makefile b/arch/x86/platform/intel/Makefile
new file mode 100644
index 000000000..dbee3b00f
--- /dev/null
+++ b/arch/x86/platform/intel/Makefile
@@ -0,0 +1,2 @@
+# SPDX-License-Identifier: GPL-2.0-only
+obj-$(CONFIG_IOSF_MBI)			+= iosf_mbi.o
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");