diff options
Diffstat (limited to 'drivers/i2c/busses/i2c-designware-baytrail.c')
| -rw-r--r-- | drivers/i2c/busses/i2c-designware-baytrail.c | 160 |
1 files changed, 160 insertions, 0 deletions
diff --git a/drivers/i2c/busses/i2c-designware-baytrail.c b/drivers/i2c/busses/i2c-designware-baytrail.c new file mode 100644 index 000000000000..5f1ff4cc5c34 --- /dev/null +++ b/drivers/i2c/busses/i2c-designware-baytrail.c @@ -0,0 +1,160 @@ +/* + * 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 + +static unsigned long acquired; + +static int get_sem(struct device *dev, u32 *sem) +{ + u32 reg_val; + int ret; + + ret = iosf_mbi_read(BT_MBI_UNIT_PMC, BT_MBI_BUNIT_READ, PUNIT_SEMAPHORE, + ®_val); + if (ret) { + dev_err(dev, "iosf failed to read punit semaphore\n"); + return ret; + } + + *sem = reg_val & 0x1; + + 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 = data & 0xfffffffe; + 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"); +} + +int baytrail_i2c_acquire(struct dw_i2c_dev *dev) +{ + u32 sem = 0; + int ret; + unsigned long start, end; + + if (!dev || !dev->dev) + return -ENODEV; + + if (!dev->acquire_lock) + return 0; + + /* host driver writes 0x2 to side band semaphore register */ + ret = iosf_mbi_write(BT_MBI_UNIT_PMC, BT_MBI_BUNIT_WRITE, + PUNIT_SEMAPHORE, 0x2); + 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); + while (!time_after(jiffies, end)) { + 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); + } + + 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; +} +EXPORT_SYMBOL(baytrail_i2c_acquire); + +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)); +} +EXPORT_SYMBOL(baytrail_i2c_release); + +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; +} +EXPORT_SYMBOL(i2c_dw_eval_lock_support); + +MODULE_AUTHOR("David E. Box <david.e.box@linux.intel.com>"); +MODULE_DESCRIPTION("Baytrail I2C Semaphore driver"); +MODULE_LICENSE("GPL v2"); |