diff options
Diffstat (limited to 'drivers/i2c/busses/i2c-designware-baytrail.c')
| -rw-r--r-- | drivers/i2c/busses/i2c-designware-baytrail.c | 179 |
1 files changed, 179 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 000000000..a2a275cfc --- /dev/null +++ b/drivers/i2c/busses/i2c-designware-baytrail.c @@ -0,0 +1,179 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Intel BayTrail PMIC I2C bus semaphore implementaion + * Copyright (c) 2014, Intel Corporation. + */ +#include <linux/delay.h> +#include <linux/device.h> +#include <linux/acpi.h> +#include <linux/i2c.h> +#include <linux/interrupt.h> +#include <linux/pm_qos.h> + +#include <asm/iosf_mbi.h> + +#include "i2c-designware-core.h" + +#define SEMAPHORE_TIMEOUT 500 +#define PUNIT_SEMAPHORE 0x7 +#define PUNIT_SEMAPHORE_CHT 0x10e +#define PUNIT_SEMAPHORE_BIT BIT(0) +#define PUNIT_SEMAPHORE_ACQUIRE BIT(1) + +static unsigned long acquired; + +static u32 get_sem_addr(struct dw_i2c_dev *dev) +{ + if (dev->flags & MODEL_CHERRYTRAIL) + return PUNIT_SEMAPHORE_CHT; + else + return PUNIT_SEMAPHORE; +} + +static int get_sem(struct dw_i2c_dev *dev, u32 *sem) +{ + u32 addr = get_sem_addr(dev); + u32 data; + int ret; + + ret = iosf_mbi_read(BT_MBI_UNIT_PMC, MBI_REG_READ, addr, &data); + if (ret) { + dev_err(dev->dev, "iosf failed to read punit semaphore\n"); + return ret; + } + + *sem = data & PUNIT_SEMAPHORE_BIT; + + return 0; +} + +static void reset_semaphore(struct dw_i2c_dev *dev) +{ + if (iosf_mbi_modify(BT_MBI_UNIT_PMC, MBI_REG_READ, get_sem_addr(dev), + 0, PUNIT_SEMAPHORE_BIT)) + dev_err(dev->dev, "iosf failed to reset punit semaphore during write\n"); + + pm_qos_update_request(&dev->pm_qos, PM_QOS_DEFAULT_VALUE); + + iosf_mbi_call_pmic_bus_access_notifier_chain(MBI_PMIC_BUS_ACCESS_END, + NULL); + iosf_mbi_punit_release(); +} + +static int baytrail_i2c_acquire(struct dw_i2c_dev *dev) +{ + u32 addr; + u32 sem = PUNIT_SEMAPHORE_ACQUIRE; + int ret; + unsigned long start, end; + + might_sleep(); + + if (!dev || !dev->dev) + return -ENODEV; + + if (!dev->release_lock) + return 0; + + iosf_mbi_punit_acquire(); + iosf_mbi_call_pmic_bus_access_notifier_chain(MBI_PMIC_BUS_ACCESS_BEGIN, + NULL); + + /* + * Disallow the CPU to enter C6 or C7 state, entering these states + * requires the punit to talk to the pmic and if this happens while + * we're holding the semaphore, the SoC hangs. + */ + pm_qos_update_request(&dev->pm_qos, 0); + + addr = get_sem_addr(dev); + + /* host driver writes to side band semaphore register */ + ret = iosf_mbi_write(BT_MBI_UNIT_PMC, MBI_REG_WRITE, addr, sem); + if (ret) { + dev_err(dev->dev, "iosf punit semaphore request failed\n"); + goto out; + } + + /* 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, &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"); +out: + reset_semaphore(dev); + + ret = iosf_mbi_read(BT_MBI_UNIT_PMC, MBI_REG_READ, addr, &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_dbg(dev->dev, "punit semaphore held for %ums\n", + jiffies_to_msecs(jiffies - acquired)); +} + +int i2c_dw_probe_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) + return 0; + + if (!iosf_mbi_available()) + return -EPROBE_DEFER; + + dev_info(dev->dev, "I2C bus managed by PUNIT\n"); + dev->acquire_lock = baytrail_i2c_acquire; + dev->release_lock = baytrail_i2c_release; + dev->pm_disabled = true; + + pm_qos_add_request(&dev->pm_qos, PM_QOS_CPU_DMA_LATENCY, + PM_QOS_DEFAULT_VALUE); + + return 0; +} + +void i2c_dw_remove_lock_support(struct dw_i2c_dev *dev) +{ + if (dev->acquire_lock) + pm_qos_remove_request(&dev->pm_qos); +} |