1 files changed, 162 insertions, 0 deletions

diff --git a/kernel/drivers/i2c/busses/i2c-designware-baytrail.c b/kernel/drivers/i2c/busses/i2c-designware-baytrail.c
new file mode 100644
index 000000000..7d7ae9747
--- /dev/null
+++ b/kernel/drivers/i2c/busses/i2c-designware-baytrail.c
@@ -0,0 +1,162 @@
+/*
+ * Intel BayTrail PMIC I2C bus semaphore implementaion
+ * Copyright (c) 2014, Intel Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ */
+#include <linux/module.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/acpi.h>
+#include <linux/i2c.h>
+#include <linux/interrupt.h>
+
+#include <asm/iosf_mbi.h>
+
+#include "i2c-designware-core.h"
+
+#define SEMAPHORE_TIMEOUT	100
+#define PUNIT_SEMAPHORE		0x7
+#define PUNIT_SEMAPHORE_BIT	BIT(0)
+#define PUNIT_SEMAPHORE_ACQUIRE	BIT(1)
+
+static unsigned long acquired;
+
+static int get_sem(struct device *dev, u32 *sem)
+{
+	u32 data;
+	int ret;
+
+	ret = iosf_mbi_read(BT_MBI_UNIT_PMC, BT_MBI_BUNIT_READ, PUNIT_SEMAPHORE,
+				&data);
+	if (ret) {
+		dev_err(dev, "iosf failed to read punit semaphore\n");
+		return ret;
+	}
+
+	*sem = data & PUNIT_SEMAPHORE_BIT;
+
+	return 0;
+}
+
+static void reset_semaphore(struct device *dev)
+{
+	u32 data;
+
+	if (iosf_mbi_read(BT_MBI_UNIT_PMC, BT_MBI_BUNIT_READ,
+				PUNIT_SEMAPHORE, &data)) {
+		dev_err(dev, "iosf failed to reset punit semaphore during read\n");
+		return;
+	}
+
+	data &= ~PUNIT_SEMAPHORE_BIT;
+	if (iosf_mbi_write(BT_MBI_UNIT_PMC, BT_MBI_BUNIT_WRITE,
+				PUNIT_SEMAPHORE, data))
+		dev_err(dev, "iosf failed to reset punit semaphore during write\n");
+}
+
+static int baytrail_i2c_acquire(struct dw_i2c_dev *dev)
+{
+	u32 sem;
+	int ret;
+	unsigned long start, end;
+
+	might_sleep();
+
+	if (!dev || !dev->dev)
+		return -ENODEV;
+
+	if (!dev->release_lock)
+		return 0;
+
+	/* host driver writes to side band semaphore register */
+	ret = iosf_mbi_write(BT_MBI_UNIT_PMC, BT_MBI_BUNIT_WRITE,
+				PUNIT_SEMAPHORE, PUNIT_SEMAPHORE_ACQUIRE);
+	if (ret) {
+		dev_err(dev->dev, "iosf punit semaphore request failed\n");
+		return ret;
+	}
+
+	/* 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->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");
+	reset_semaphore(dev->dev);
+
+	ret = iosf_mbi_read(BT_MBI_UNIT_PMC, BT_MBI_BUNIT_READ,
+				PUNIT_SEMAPHORE, &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);
+	dev_dbg(dev->dev, "punit semaphore held for %ums\n",
+		jiffies_to_msecs(jiffies - acquired));
+}
+
+int i2c_dw_eval_lock_support(struct dw_i2c_dev *dev)
+{
+	acpi_status status;
+	unsigned long long shared_host = 0;
+	acpi_handle handle;
+
+	if (!dev || !dev->dev)
+		return 0;
+
+	handle = ACPI_HANDLE(dev->dev);
+	if (!handle)
+		return 0;
+
+	status = acpi_evaluate_integer(handle, "_SEM", NULL, &shared_host);
+	if (ACPI_FAILURE(status))
+		return 0;
+
+	if (shared_host) {
+		dev_info(dev->dev, "I2C bus managed by PUNIT\n");
+		dev->acquire_lock = baytrail_i2c_acquire;
+		dev->release_lock = baytrail_i2c_release;
+		dev->pm_runtime_disabled = true;
+	}
+
+	if (!iosf_mbi_available())
+		return -EPROBE_DEFER;
+
+	return 0;
+}
+
+MODULE_AUTHOR("David E. Box <david.e.box@linux.intel.com>");
+MODULE_DESCRIPTION("Baytrail I2C Semaphore driver");
+MODULE_LICENSE("GPL v2");