LXR linux/drivers/i2c/busses/i2c-designware-slave.c

   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * Synopsys DesignWare I2C adapter driver (slave only).
   4 *
   5 * Based on the Synopsys DesignWare I2C adapter driver (master).
   6 *
   7 * Copyright (C) 2016 Synopsys Inc.
   8 */
   9#include <linux/delay.h>
  10#include <linux/err.h>
  11#include <linux/errno.h>
  12#include <linux/i2c.h>
  13#include <linux/interrupt.h>
  14#include <linux/io.h>
  15#include <linux/module.h>
  16#include <linux/pm_runtime.h>
  17#include <linux/regmap.h>
  18
  19#include "i2c-designware-core.h"
  20
  21static void i2c_dw_configure_fifo_slave(struct dw_i2c_dev *dev)
  22{
  23        /* Configure Tx/Rx FIFO threshold levels. */
  24        regmap_write(dev->map, DW_IC_TX_TL, 0);
  25        regmap_write(dev->map, DW_IC_RX_TL, 0);
  26
  27        /* Configure the I2C slave. */
  28        regmap_write(dev->map, DW_IC_CON, dev->slave_cfg);
  29        regmap_write(dev->map, DW_IC_INTR_MASK, DW_IC_INTR_SLAVE_MASK);
  30}
  31
  32/**
  33 * i2c_dw_init_slave() - Initialize the designware i2c slave hardware
  34 * @dev: device private data
  35 *
  36 * This function configures and enables the I2C in slave mode.
  37 * This function is called during I2C init function, and in case of timeout at
  38 * run time.
  39 */
  40static int i2c_dw_init_slave(struct dw_i2c_dev *dev)
  41{
  42        int ret;
  43
  44        ret = i2c_dw_acquire_lock(dev);
  45        if (ret)
  46                return ret;
  47
  48        /* Disable the adapter. */
  49        __i2c_dw_disable(dev);
  50
  51        /* Write SDA hold time if supported */
  52        if (dev->sda_hold_time)
  53                regmap_write(dev->map, DW_IC_SDA_HOLD, dev->sda_hold_time);
  54
  55        i2c_dw_configure_fifo_slave(dev);
  56        i2c_dw_release_lock(dev);
  57
  58        return 0;
  59}
  60
  61static int i2c_dw_reg_slave(struct i2c_client *slave)
  62{
  63        struct dw_i2c_dev *dev = i2c_get_adapdata(slave->adapter);
  64
  65        if (dev->slave)
  66                return -EBUSY;
  67        if (slave->flags & I2C_CLIENT_TEN)
  68                return -EAFNOSUPPORT;
  69        pm_runtime_get_sync(dev->dev);
  70
  71        /*
  72         * Set slave address in the IC_SAR register,
  73         * the address to which the DW_apb_i2c responds.
  74         */
  75        __i2c_dw_disable_nowait(dev);
  76        regmap_write(dev->map, DW_IC_SAR, slave->addr);
  77        dev->slave = slave;
  78
  79        __i2c_dw_enable(dev);
  80
  81        dev->cmd_err = 0;
  82        dev->msg_write_idx = 0;
  83        dev->msg_read_idx = 0;
  84        dev->msg_err = 0;
  85        dev->status = STATUS_IDLE;
  86        dev->abort_source = 0;
  87        dev->rx_outstanding = 0;
  88
  89        return 0;
  90}
  91
  92static int i2c_dw_unreg_slave(struct i2c_client *slave)
  93{
  94        struct dw_i2c_dev *dev = i2c_get_adapdata(slave->adapter);
  95
  96        dev->disable_int(dev);
  97        dev->disable(dev);
  98        synchronize_irq(dev->irq);
  99        dev->slave = NULL;
 100        pm_runtime_put(dev->dev);
 101
 102        return 0;
 103}
 104
 105static u32 i2c_dw_read_clear_intrbits_slave(struct dw_i2c_dev *dev)
 106{
 107        u32 stat, dummy;
 108
 109        /*
 110         * The IC_INTR_STAT register just indicates "enabled" interrupts.
 111         * The unmasked raw version of interrupt status bits is available
 112         * in the IC_RAW_INTR_STAT register.
 113         *
 114         * That is,
 115         *   stat = readl(IC_INTR_STAT);
 116         * equals to,
 117         *   stat = readl(IC_RAW_INTR_STAT) & readl(IC_INTR_MASK);
 118         *
 119         * The raw version might be useful for debugging purposes.
 120         */
 121        regmap_read(dev->map, DW_IC_INTR_STAT, &stat);
 122
 123        /*
 124         * Do not use the IC_CLR_INTR register to clear interrupts, or
 125         * you'll miss some interrupts, triggered during the period from
 126         * readl(IC_INTR_STAT) to readl(IC_CLR_INTR).
 127         *
 128         * Instead, use the separately-prepared IC_CLR_* registers.
 129         */
 130        if (stat & DW_IC_INTR_TX_ABRT)
 131                regmap_read(dev->map, DW_IC_CLR_TX_ABRT, &dummy);
 132        if (stat & DW_IC_INTR_RX_UNDER)
 133                regmap_read(dev->map, DW_IC_CLR_RX_UNDER, &dummy);
 134        if (stat & DW_IC_INTR_RX_OVER)
 135                regmap_read(dev->map, DW_IC_CLR_RX_OVER, &dummy);
 136        if (stat & DW_IC_INTR_TX_OVER)
 137                regmap_read(dev->map, DW_IC_CLR_TX_OVER, &dummy);
 138        if (stat & DW_IC_INTR_RX_DONE)
 139                regmap_read(dev->map, DW_IC_CLR_RX_DONE, &dummy);
 140        if (stat & DW_IC_INTR_ACTIVITY)
 141                regmap_read(dev->map, DW_IC_CLR_ACTIVITY, &dummy);
 142        if (stat & DW_IC_INTR_STOP_DET)
 143                regmap_read(dev->map, DW_IC_CLR_STOP_DET, &dummy);
 144        if (stat & DW_IC_INTR_START_DET)
 145                regmap_read(dev->map, DW_IC_CLR_START_DET, &dummy);
 146        if (stat & DW_IC_INTR_GEN_CALL)
 147                regmap_read(dev->map, DW_IC_CLR_GEN_CALL, &dummy);
 148
 149        return stat;
 150}
 151
 152/*
 153 * Interrupt service routine. This gets called whenever an I2C slave interrupt
 154 * occurs.
 155 */
 156
 157static int i2c_dw_irq_handler_slave(struct dw_i2c_dev *dev)
 158{
 159        u32 raw_stat, stat, enabled, tmp;
 160        u8 val = 0, slave_activity;
 161
 162        regmap_read(dev->map, DW_IC_ENABLE, &enabled);
 163        regmap_read(dev->map, DW_IC_RAW_INTR_STAT, &raw_stat);
 164        regmap_read(dev->map, DW_IC_STATUS, &tmp);
 165        slave_activity = ((tmp & DW_IC_STATUS_SLAVE_ACTIVITY) >> 6);
 166
 167        if (!enabled || !(raw_stat & ~DW_IC_INTR_ACTIVITY) || !dev->slave)
 168                return 0;
 169
 170        stat = i2c_dw_read_clear_intrbits_slave(dev);
 171        dev_dbg(dev->dev,
 172                "%#x STATUS SLAVE_ACTIVITY=%#x : RAW_INTR_STAT=%#x : INTR_STAT=%#x\n",
 173                enabled, slave_activity, raw_stat, stat);
 174
 175        if (stat & DW_IC_INTR_RX_FULL) {
 176                if (dev->status != STATUS_WRITE_IN_PROGRESS) {
 177                        dev->status = STATUS_WRITE_IN_PROGRESS;
 178                        i2c_slave_event(dev->slave, I2C_SLAVE_WRITE_REQUESTED,
 179                                        &val);
 180                }
 181
 182                regmap_read(dev->map, DW_IC_DATA_CMD, &tmp);
 183                val = tmp;
 184                if (!i2c_slave_event(dev->slave, I2C_SLAVE_WRITE_RECEIVED,
 185                                     &val))
 186                        dev_vdbg(dev->dev, "Byte %X acked!", val);
 187        }
 188
 189        if (stat & DW_IC_INTR_RD_REQ) {
 190                if (slave_activity) {
 191                        regmap_read(dev->map, DW_IC_CLR_RD_REQ, &tmp);
 192
 193                        dev->status = STATUS_READ_IN_PROGRESS;
 194                        if (!i2c_slave_event(dev->slave,
 195                                             I2C_SLAVE_READ_REQUESTED,
 196                                             &val))
 197                                regmap_write(dev->map, DW_IC_DATA_CMD, val);
 198                }
 199        }
 200
 201        if (stat & DW_IC_INTR_RX_DONE) {
 202                if (!i2c_slave_event(dev->slave, I2C_SLAVE_READ_PROCESSED,
 203                                     &val))
 204                        regmap_read(dev->map, DW_IC_CLR_RX_DONE, &tmp);
 205        }
 206
 207        if (stat & DW_IC_INTR_STOP_DET) {
 208                dev->status = STATUS_IDLE;
 209                i2c_slave_event(dev->slave, I2C_SLAVE_STOP, &val);
 210        }
 211
 212        return 1;
 213}
 214
 215static irqreturn_t i2c_dw_isr_slave(int this_irq, void *dev_id)
 216{
 217        struct dw_i2c_dev *dev = dev_id;
 218        int ret;
 219
 220        ret = i2c_dw_irq_handler_slave(dev);
 221        if (ret > 0)
 222                complete(&dev->cmd_complete);
 223
 224        return IRQ_RETVAL(ret);
 225}
 226
 227static const struct i2c_algorithm i2c_dw_algo = {
 228        .functionality = i2c_dw_func,
 229        .reg_slave = i2c_dw_reg_slave,
 230        .unreg_slave = i2c_dw_unreg_slave,
 231};
 232
 233void i2c_dw_configure_slave(struct dw_i2c_dev *dev)
 234{
 235        dev->functionality = I2C_FUNC_SLAVE | DW_IC_DEFAULT_FUNCTIONALITY;
 236
 237        dev->slave_cfg = DW_IC_CON_RX_FIFO_FULL_HLD_CTRL |
 238                         DW_IC_CON_RESTART_EN | DW_IC_CON_STOP_DET_IFADDRESSED;
 239
 240        dev->mode = DW_IC_SLAVE;
 241}
 242EXPORT_SYMBOL_GPL(i2c_dw_configure_slave);
 243
 244int i2c_dw_probe_slave(struct dw_i2c_dev *dev)
 245{
 246        struct i2c_adapter *adap = &dev->adapter;
 247        int ret;
 248
 249        init_completion(&dev->cmd_complete);
 250
 251        dev->init = i2c_dw_init_slave;
 252        dev->disable = i2c_dw_disable;
 253        dev->disable_int = i2c_dw_disable_int;
 254
 255        ret = i2c_dw_init_regmap(dev);
 256        if (ret)
 257                return ret;
 258
 259        ret = i2c_dw_set_sda_hold(dev);
 260        if (ret)
 261                return ret;
 262
 263        ret = i2c_dw_set_fifo_size(dev);
 264        if (ret)
 265                return ret;
 266
 267        ret = dev->init(dev);
 268        if (ret)
 269                return ret;
 270
 271        snprintf(adap->name, sizeof(adap->name),
 272                 "Synopsys DesignWare I2C Slave adapter");
 273        adap->retries = 3;
 274        adap->algo = &i2c_dw_algo;
 275        adap->dev.parent = dev->dev;
 276        i2c_set_adapdata(adap, dev);
 277
 278        ret = devm_request_irq(dev->dev, dev->irq, i2c_dw_isr_slave,
 279                               IRQF_SHARED, dev_name(dev->dev), dev);
 280        if (ret) {
 281                dev_err(dev->dev, "failure requesting irq %i: %d\n",
 282                        dev->irq, ret);
 283                return ret;
 284        }
 285
 286        ret = i2c_add_numbered_adapter(adap);
 287        if (ret)
 288                dev_err(dev->dev, "failure adding adapter: %d\n", ret);
 289
 290        return ret;
 291}
 292EXPORT_SYMBOL_GPL(i2c_dw_probe_slave);
 293
 294MODULE_AUTHOR("Luis Oliveira <lolivei@synopsys.com>");
 295MODULE_DESCRIPTION("Synopsys DesignWare I2C bus slave adapter");
 296MODULE_LICENSE("GPL v2");
 297