diff options
Diffstat (limited to 'drivers/i2c/busses/i2c-designware-slave.c')
| -rw-r--r-- | drivers/i2c/busses/i2c-designware-slave.c | 281 |
1 files changed, 281 insertions, 0 deletions
diff --git a/drivers/i2c/busses/i2c-designware-slave.c b/drivers/i2c/busses/i2c-designware-slave.c new file mode 100644 index 0000000000..2e079cf20b --- /dev/null +++ b/drivers/i2c/busses/i2c-designware-slave.c @@ -0,0 +1,281 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Synopsys DesignWare I2C adapter driver (slave only). + * + * Based on the Synopsys DesignWare I2C adapter driver (master). + * + * Copyright (C) 2016 Synopsys Inc. + */ +#include <linux/delay.h> +#include <linux/err.h> +#include <linux/errno.h> +#include <linux/i2c.h> +#include <linux/interrupt.h> +#include <linux/io.h> +#include <linux/module.h> +#include <linux/pm_runtime.h> +#include <linux/regmap.h> + +#include "i2c-designware-core.h" + +static void i2c_dw_configure_fifo_slave(struct dw_i2c_dev *dev) +{ + /* Configure Tx/Rx FIFO threshold levels. */ + regmap_write(dev->map, DW_IC_TX_TL, 0); + regmap_write(dev->map, DW_IC_RX_TL, 0); + + /* Configure the I2C slave. */ + regmap_write(dev->map, DW_IC_CON, dev->slave_cfg); + regmap_write(dev->map, DW_IC_INTR_MASK, DW_IC_INTR_SLAVE_MASK); +} + +/** + * i2c_dw_init_slave() - Initialize the designware i2c slave hardware + * @dev: device private data + * + * This function configures and enables the I2C in slave mode. + * This function is called during I2C init function, and in case of timeout at + * run time. + */ +static int i2c_dw_init_slave(struct dw_i2c_dev *dev) +{ + int ret; + + ret = i2c_dw_acquire_lock(dev); + if (ret) + return ret; + + /* Disable the adapter. */ + __i2c_dw_disable(dev); + + /* Write SDA hold time if supported */ + if (dev->sda_hold_time) + regmap_write(dev->map, DW_IC_SDA_HOLD, dev->sda_hold_time); + + i2c_dw_configure_fifo_slave(dev); + i2c_dw_release_lock(dev); + + return 0; +} + +static int i2c_dw_reg_slave(struct i2c_client *slave) +{ + struct dw_i2c_dev *dev = i2c_get_adapdata(slave->adapter); + + if (dev->slave) + return -EBUSY; + if (slave->flags & I2C_CLIENT_TEN) + return -EAFNOSUPPORT; + pm_runtime_get_sync(dev->dev); + + /* + * Set slave address in the IC_SAR register, + * the address to which the DW_apb_i2c responds. + */ + __i2c_dw_disable_nowait(dev); + regmap_write(dev->map, DW_IC_SAR, slave->addr); + dev->slave = slave; + + __i2c_dw_enable(dev); + + dev->status = 0; + + return 0; +} + +static int i2c_dw_unreg_slave(struct i2c_client *slave) +{ + struct dw_i2c_dev *dev = i2c_get_adapdata(slave->adapter); + + regmap_write(dev->map, DW_IC_INTR_MASK, 0); + dev->disable(dev); + synchronize_irq(dev->irq); + dev->slave = NULL; + pm_runtime_put(dev->dev); + + return 0; +} + +static u32 i2c_dw_read_clear_intrbits_slave(struct dw_i2c_dev *dev) +{ + unsigned int stat, dummy; + + /* + * The IC_INTR_STAT register just indicates "enabled" interrupts. + * The unmasked raw version of interrupt status bits is available + * in the IC_RAW_INTR_STAT register. + * + * That is, + * stat = readl(IC_INTR_STAT); + * equals to, + * stat = readl(IC_RAW_INTR_STAT) & readl(IC_INTR_MASK); + * + * The raw version might be useful for debugging purposes. + */ + regmap_read(dev->map, DW_IC_INTR_STAT, &stat); + + /* + * Do not use the IC_CLR_INTR register to clear interrupts, or + * you'll miss some interrupts, triggered during the period from + * readl(IC_INTR_STAT) to readl(IC_CLR_INTR). + * + * Instead, use the separately-prepared IC_CLR_* registers. + */ + if (stat & DW_IC_INTR_TX_ABRT) + regmap_read(dev->map, DW_IC_CLR_TX_ABRT, &dummy); + if (stat & DW_IC_INTR_RX_UNDER) + regmap_read(dev->map, DW_IC_CLR_RX_UNDER, &dummy); + if (stat & DW_IC_INTR_RX_OVER) + regmap_read(dev->map, DW_IC_CLR_RX_OVER, &dummy); + if (stat & DW_IC_INTR_TX_OVER) + regmap_read(dev->map, DW_IC_CLR_TX_OVER, &dummy); + if (stat & DW_IC_INTR_RX_DONE) + regmap_read(dev->map, DW_IC_CLR_RX_DONE, &dummy); + if (stat & DW_IC_INTR_ACTIVITY) + regmap_read(dev->map, DW_IC_CLR_ACTIVITY, &dummy); + if (stat & DW_IC_INTR_STOP_DET) + regmap_read(dev->map, DW_IC_CLR_STOP_DET, &dummy); + if (stat & DW_IC_INTR_START_DET) + regmap_read(dev->map, DW_IC_CLR_START_DET, &dummy); + if (stat & DW_IC_INTR_GEN_CALL) + regmap_read(dev->map, DW_IC_CLR_GEN_CALL, &dummy); + + return stat; +} + +/* + * Interrupt service routine. This gets called whenever an I2C slave interrupt + * occurs. + */ +static irqreturn_t i2c_dw_isr_slave(int this_irq, void *dev_id) +{ + struct dw_i2c_dev *dev = dev_id; + unsigned int raw_stat, stat, enabled, tmp; + u8 val = 0, slave_activity; + + regmap_read(dev->map, DW_IC_ENABLE, &enabled); + regmap_read(dev->map, DW_IC_RAW_INTR_STAT, &raw_stat); + regmap_read(dev->map, DW_IC_STATUS, &tmp); + slave_activity = ((tmp & DW_IC_STATUS_SLAVE_ACTIVITY) >> 6); + + if (!enabled || !(raw_stat & ~DW_IC_INTR_ACTIVITY) || !dev->slave) + return IRQ_NONE; + + stat = i2c_dw_read_clear_intrbits_slave(dev); + dev_dbg(dev->dev, + "%#x STATUS SLAVE_ACTIVITY=%#x : RAW_INTR_STAT=%#x : INTR_STAT=%#x\n", + enabled, slave_activity, raw_stat, stat); + + if (stat & DW_IC_INTR_RX_FULL) { + if (!(dev->status & STATUS_WRITE_IN_PROGRESS)) { + dev->status |= STATUS_WRITE_IN_PROGRESS; + dev->status &= ~STATUS_READ_IN_PROGRESS; + i2c_slave_event(dev->slave, I2C_SLAVE_WRITE_REQUESTED, + &val); + } + + do { + regmap_read(dev->map, DW_IC_DATA_CMD, &tmp); + if (tmp & DW_IC_DATA_CMD_FIRST_DATA_BYTE) + i2c_slave_event(dev->slave, + I2C_SLAVE_WRITE_REQUESTED, + &val); + val = tmp; + i2c_slave_event(dev->slave, I2C_SLAVE_WRITE_RECEIVED, + &val); + regmap_read(dev->map, DW_IC_STATUS, &tmp); + } while (tmp & DW_IC_STATUS_RFNE); + } + + if (stat & DW_IC_INTR_RD_REQ) { + if (slave_activity) { + regmap_read(dev->map, DW_IC_CLR_RD_REQ, &tmp); + + if (!(dev->status & STATUS_READ_IN_PROGRESS)) { + i2c_slave_event(dev->slave, + I2C_SLAVE_READ_REQUESTED, + &val); + dev->status |= STATUS_READ_IN_PROGRESS; + dev->status &= ~STATUS_WRITE_IN_PROGRESS; + } else { + i2c_slave_event(dev->slave, + I2C_SLAVE_READ_PROCESSED, + &val); + } + regmap_write(dev->map, DW_IC_DATA_CMD, val); + } + } + + if (stat & DW_IC_INTR_STOP_DET) + i2c_slave_event(dev->slave, I2C_SLAVE_STOP, &val); + + return IRQ_HANDLED; +} + +static const struct i2c_algorithm i2c_dw_algo = { + .functionality = i2c_dw_func, + .reg_slave = i2c_dw_reg_slave, + .unreg_slave = i2c_dw_unreg_slave, +}; + +void i2c_dw_configure_slave(struct dw_i2c_dev *dev) +{ + dev->functionality = I2C_FUNC_SLAVE | DW_IC_DEFAULT_FUNCTIONALITY; + + dev->slave_cfg = DW_IC_CON_RX_FIFO_FULL_HLD_CTRL | + DW_IC_CON_RESTART_EN | DW_IC_CON_STOP_DET_IFADDRESSED; + + dev->mode = DW_IC_SLAVE; +} +EXPORT_SYMBOL_GPL(i2c_dw_configure_slave); + +int i2c_dw_probe_slave(struct dw_i2c_dev *dev) +{ + struct i2c_adapter *adap = &dev->adapter; + int ret; + + dev->init = i2c_dw_init_slave; + dev->disable = i2c_dw_disable; + + ret = i2c_dw_init_regmap(dev); + if (ret) + return ret; + + ret = i2c_dw_set_sda_hold(dev); + if (ret) + return ret; + + ret = i2c_dw_set_fifo_size(dev); + if (ret) + return ret; + + ret = dev->init(dev); + if (ret) + return ret; + + snprintf(adap->name, sizeof(adap->name), + "Synopsys DesignWare I2C Slave adapter"); + adap->retries = 3; + adap->algo = &i2c_dw_algo; + adap->dev.parent = dev->dev; + i2c_set_adapdata(adap, dev); + + ret = devm_request_irq(dev->dev, dev->irq, i2c_dw_isr_slave, + IRQF_SHARED, dev_name(dev->dev), dev); + if (ret) { + dev_err(dev->dev, "failure requesting irq %i: %d\n", + dev->irq, ret); + return ret; + } + + ret = i2c_add_numbered_adapter(adap); + if (ret) + dev_err(dev->dev, "failure adding adapter: %d\n", ret); + + return ret; +} +EXPORT_SYMBOL_GPL(i2c_dw_probe_slave); + +MODULE_AUTHOR("Luis Oliveira <lolivei@synopsys.com>"); +MODULE_DESCRIPTION("Synopsys DesignWare I2C bus slave adapter"); +MODULE_LICENSE("GPL v2"); |