[deliverable/linux.git] / drivers / i2c / busses / i2c-designware-baytrail.c

/*
 * 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");
Commit	Line	Data
894acb2f DB	1	/*
	2	* Intel BayTrail PMIC I2C bus semaphore implementaion
	3	* Copyright (c) 2014, Intel Corporation.
	4	*
	5	* This program is free software; you can redistribute it and/or modify it
	6	* under the terms and conditions of the GNU General Public License,
	7	* version 2, as published by the Free Software Foundation.
	8	*
	9	* This program is distributed in the hope it will be useful, but WITHOUT
	10	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
	11	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
	12	* more details.
	13	*/
	14	#include <linux/module.h>
	15	#include <linux/delay.h>
	16	#include <linux/device.h>
	17	#include <linux/acpi.h>
	18	#include <linux/i2c.h>
	19	#include <linux/interrupt.h>
c8e043e6	20
894acb2f	21	#include <asm/iosf_mbi.h>
c8e043e6	22
894acb2f DB	23	#include "i2c-designware-core.h"
	24
	25	#define SEMAPHORE_TIMEOUT 100
	26	#define PUNIT_SEMAPHORE 0x7
9b5c9f04 AS	27	#define PUNIT_SEMAPHORE_BIT BIT(0)
9b5c9f04 AS	28	#define PUNIT_SEMAPHORE_ACQUIRE BIT(1)
894acb2f DB	29
	30	static unsigned long acquired;
	31
	32	static int get_sem(struct device dev, u32 sem)
	33	{
9b5c9f04	34	u32 data;
894acb2f DB	35	int ret;
	36
	37	ret = iosf_mbi_read(BT_MBI_UNIT_PMC, BT_MBI_BUNIT_READ, PUNIT_SEMAPHORE,
9b5c9f04	38	&data);
894acb2f DB	39	if (ret) {
	40	dev_err(dev, "iosf failed to read punit semaphore\n");
	41	return ret;
	42	}
	43
9b5c9f04	44	*sem = data & PUNIT_SEMAPHORE_BIT;
894acb2f DB	45
	46	return 0;
	47	}
	48
	49	static void reset_semaphore(struct device *dev)
	50	{
	51	u32 data;
	52
	53	if (iosf_mbi_read(BT_MBI_UNIT_PMC, BT_MBI_BUNIT_READ,
	54	PUNIT_SEMAPHORE, &data)) {
	55	dev_err(dev, "iosf failed to reset punit semaphore during read\n");
	56	return;
	57	}
	58
9b5c9f04	59	data &= ~PUNIT_SEMAPHORE_BIT;
894acb2f	60	if (iosf_mbi_write(BT_MBI_UNIT_PMC, BT_MBI_BUNIT_WRITE,
9b5c9f04	61	PUNIT_SEMAPHORE, data))
894acb2f DB	62	dev_err(dev, "iosf failed to reset punit semaphore during write\n");
	63	}
	64
c8e043e6	65	static int baytrail_i2c_acquire(struct dw_i2c_dev *dev)
894acb2f	66	{
c8e043e6	67	u32 sem;
894acb2f DB	68	int ret;
	69	unsigned long start, end;
	70
ebf2ef8f AS	71	might_sleep();
ebf2ef8f AS	72
894acb2f DB	73	if (!dev \|\| !dev->dev)
	74	return -ENODEV;
	75
30be774b	76	if (!dev->release_lock)
894acb2f DB	77	return 0;
894acb2f DB	78
9b5c9f04	79	/* host driver writes to side band semaphore register */
894acb2f	80	ret = iosf_mbi_write(BT_MBI_UNIT_PMC, BT_MBI_BUNIT_WRITE,
9b5c9f04	81	PUNIT_SEMAPHORE, PUNIT_SEMAPHORE_ACQUIRE);
894acb2f DB	82	if (ret) {
	83	dev_err(dev->dev, "iosf punit semaphore request failed\n");
	84	return ret;
	85	}
	86
	87	/* host driver waits for bit 0 to be set in semaphore register */
	88	start = jiffies;
	89	end = start + msecs_to_jiffies(SEMAPHORE_TIMEOUT);
ebf2ef8f	90	do {
894acb2f DB	91	ret = get_sem(dev->dev, &sem);
	92	if (!ret && sem) {
	93	acquired = jiffies;
	94	dev_dbg(dev->dev, "punit semaphore acquired after %ums\n",
	95	jiffies_to_msecs(jiffies - start));
	96	return 0;
	97	}
	98
	99	usleep_range(1000, 2000);
ebf2ef8f	100	} while (time_before(jiffies, end));
894acb2f DB	101
	102	dev_err(dev->dev, "punit semaphore timed out, resetting\n");
	103	reset_semaphore(dev->dev);
	104
	105	ret = iosf_mbi_read(BT_MBI_UNIT_PMC, BT_MBI_BUNIT_READ,
259aada4 AS	106	PUNIT_SEMAPHORE, &sem);
259aada4 AS	107	if (ret)
894acb2f DB	108	dev_err(dev->dev, "iosf failed to read punit semaphore\n");
	109	else
	110	dev_err(dev->dev, "PUNIT SEM: %d\n", sem);
	111
	112	WARN_ON(1);
	113
	114	return -ETIMEDOUT;
	115	}
894acb2f	116
c8e043e6	117	static void baytrail_i2c_release(struct dw_i2c_dev *dev)
894acb2f DB	118	{
	119	if (!dev \|\| !dev->dev)
	120	return;
	121
	122	if (!dev->acquire_lock)
	123	return;
	124
	125	reset_semaphore(dev->dev);
	126	dev_dbg(dev->dev, "punit semaphore held for %ums\n",
	127	jiffies_to_msecs(jiffies - acquired));
	128	}
894acb2f DB	129
	130	int i2c_dw_eval_lock_support(struct dw_i2c_dev *dev)
	131	{
	132	acpi_status status;
	133	unsigned long long shared_host = 0;
	134	acpi_handle handle;
	135
	136	if (!dev \|\| !dev->dev)
	137	return 0;
	138
	139	handle = ACPI_HANDLE(dev->dev);
	140	if (!handle)
	141	return 0;
	142
	143	status = acpi_evaluate_integer(handle, "_SEM", NULL, &shared_host);
894acb2f DB	144	if (ACPI_FAILURE(status))
	145	return 0;
	146
	147	if (shared_host) {
	148	dev_info(dev->dev, "I2C bus managed by PUNIT\n");
	149	dev->acquire_lock = baytrail_i2c_acquire;
	150	dev->release_lock = baytrail_i2c_release;
	151	dev->pm_runtime_disabled = true;
	152	}
	153
	154	if (!iosf_mbi_available())
	155	return -EPROBE_DEFER;
	156
	157	return 0;
	158	}
894acb2f DB	159
	160	MODULE_AUTHOR("David E. Box <david.e.box@linux.intel.com>");
	161	MODULE_DESCRIPTION("Baytrail I2C Semaphore driver");
	162	MODULE_LICENSE("GPL v2");